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For investors outside the United States: Neither we nor any of the underwriters have done anything that would permit the global offering or possession or distribution of this prospectus in any jurisdiction where action for that purpose is required, other than in the United States. Persons outside the United States who come into possession of this prospectus must inform themselves about, and observe any restrictions relating to, the global offering of the ADSs or the ordinary shares and the distribution of this prospectus outside the United States.

We are incorporated in Belgium, and a majority of our outstanding securities are owned by non-U.S. residents. Under the rules of the U.S. Securities and Exchange Commission, or SEC, we are currently eligible for treatment as a “foreign private issuer.” As a foreign private issuer, we will not be required to file periodic reports and financial statements with the SEC as frequently or as promptly as domestic registrants whose securities are registered under the Securities Exchange Act of 1934, as amended.

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Our financial statements are presented in euros. All references in this prospectus to “$,” “US$,” “U.S.$,” “U.S. dollars,” “dollars” and “USD” mean U.S. dollars and all references to “€” and “euros” mean euros, unless otherwise noted. Throughout this prospectus, references to ADSs mean ADSs or ordinary shares represented by ADSs, as the case may be.

Through and including                     , 2015 (the 25th day after the date of this prospectus) federal securities law may require all dealers that effect transactions in these securities, whether or not participating in the global offering, to deliver a prospectus. This is in addition to the dealers’ obligations to deliver a prospectus when acting as underwriters and with respect to their unsold allotments or subscriptions.

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Risk factors

Investing in the ADSs or ordinary shares involves a high degree of risk. You should carefully consider the following risks and all other information contained in this prospectus, including our consolidated financial statements and the related notes contained elsewhere in this prospectus, before making an investment decision regarding our securities. The risks and uncertainties described below are those significant risk factors, currently known and specific to us, that we believe are relevant to an investment in our securities. If any of these risks materialize, our business, financial condition or results of operations could suffer, the price of the ADSs or ordinary shares could decline and you could lose part or all of your investment.

Risks Related to Our Financial Position and Need for Additional Capital

We have incurred losses in each period since our inception and anticipate that we will continue to incur losses in the future.

We are not profitable and have incurred losses in each period since our inception. For the years ended December 31, 2014 and 2013, we incurred a loss for the year of €16.5 million and €14.5 million, respectively. As of December 31, 2014, we had a retained loss of €71.2 million. We expect these losses to increase as we continue to incur significant research and development and other expenses related to our ongoing operations, continue to advance our drug product candidates through pre-clinical studies and clinical trials, seek regulatory approvals for our drug product candidates, scale-up manufacturing capabilities and hire additional personnel to support the development of our drug product candidates and to enhance our operational, financial and information management systems.

Even if we succeed in commercializing one or more of our drug product candidates, we will continue to incur losses for the foreseeable future relating to our substantial research and development expenditures to develop our technologies. We anticipate that our expenses will increase substantially if and as we:

We may encounter unforeseen expenses, difficulties, complications, delays and other unknown factors that may adversely affect our business. The size of our future losses will depend, in part, on the rate of future growth of our expenses and our ability to generate revenue.

Our prior losses and expected future losses have had and will continue to have an adverse effect on our shareholders’ equity and working capital. Further, the losses we incur may fluctuate significantly from

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quarter to quarter and year to year, such that a period to period comparison of our results of operations may not be a good indication of our future performance.

We have generated only limited revenue from sales of C-Cath _ez to date, and do not expect to generate material revenue until we receive regulatory approval for one of our drug product candidates.

We have generated only limited revenue from sales of C-Cath _ez , our proprietary catheter for injecting cells into the heart, to research laboratories and clinical stage companies. We expect that revenue from sales of C-Cath _ez will remain insignificant as we sell C-Cath _ez only to research laboratories and clinical stage companies. We have no drug products approved for commercial sale, have not generated any revenue from drug product sales, and do not anticipate generating any revenue from drug product sales until after we have received regulatory approval, if at all, for the commercial sale of a drug product candidate. As of the date of this prospectus, C-Cure, our lead drug product candidate in cardiovascular disease, is in Phase 3 clinical development for the treatment of ischemic heart failure, or HF, while CAR-NKG2D, our lead drug product candidate in oncology, is in Phase 1 clinical development for the treatment of refractory or relapsed acute myeloid leukemia, or AML, and multiple myeloma, or MM. Our ability to generate revenue and achieve profitability depends significantly on our success in many factors, including:

Even if one or more of the drug product candidates that we develop is approved for commercial sale, we anticipate incurring significant costs associated with commercializing any approved drug product candidate. Our expenses could increase beyond expectations if we are required by the U.S. Food and Drug Administration, or the FDA, European Medicines Agency, or EMA, or other applicable regulatory agencies, to change our manufacturing processes or assays, or to perform clinical, pre-clinical, or other types of studies in addition to those that we currently anticipate. If we are successful in obtaining regulatory approvals to market one or more of our drug product candidates, our revenue will be dependent, in part, upon the size of the markets in the territories for which we gain regulatory approval, the accepted price for the drug product, the ability to get coverage and adequate reimbursement, and whether we own the commercial rights for that territory. If the number of our addressable disease

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patients is not as significant as we estimate, the indication approved by regulatory authorities is narrower than we expect, or the reasonably accepted population for treatment is narrowed by competition, physician choice or treatment guidelines, we may not generate significant revenue from sales of such products, even if approved. If we are not able to generate revenue from the sale of any approved drug products, we may never become profitable.

If we fail to obtain additional financing, we will be unable to complete the development and commercialization of our drug product candidates.

Our operations have required substantial amounts of cash since inception. We expect to continue to spend substantial amounts to continue the clinical development of our drug product candidates, including our ongoing and planned clinical trials for C-Cure, CAR-NKG2D and any of our future drug product candidates. If approved, we will require significant additional amounts in order to launch and commercialize our drug product candidates.

As of December 31, 2014, we had €27.6 million in cash and €2.7 million in short term investments. In March 2015, we raised an additional €31.7 million though a private placement. We estimate that our net proceeds from the global offering will be approximately $89.5 million (€79.4 million), assuming a public offering price of $70.98 (€62.94) per ADS in the U.S. offering and €62.94 per ordinary share in the European private placement, the last reported sale price of our ordinary shares on Euronext Brussels on June 12, 2015, after deducting the underwriting commissions and estimated offering expenses payable by us. We expect to use the net proceeds from the global offering to advance the development of C-Cure through Phase 3 clinical development as a treatment for ischemic HF, to advance the development of CAR-NKG2D through Phase 1 clinical development as a treatment for AML and MM, to advance additional CAR T-cell therapy drug product candidates for the treatment of additional blood cancers and solid tumors, to support our growth globally by expanding general, administrative and operational functions in our headquarters in Belgium and in the United States, and the remainder for working capital and other general corporate purposes.

We believe that such proceeds, together with our existing cash, will be sufficient to fund our operations until at least the end of 2017. However, changing circumstances may cause us to increase our spending significantly faster than we currently anticipate, and we may need to spend more money than currently expected because of circumstances beyond our control. We may require additional capital for the further development and commercialization of our drug product candidates and may need to raise additional funds sooner if we choose to expand more rapidly than we presently anticipate.

We cannot be certain that additional funding will be available on acceptable terms, or at all. We have no committed source of additional capital and if we are unable to raise additional capital in sufficient amounts or on terms acceptable to us, we may have to significantly delay, scale back or discontinue the development or commercialization of our drug product candidates or other research and development initiatives. Our licenses may also be terminated if we are unable to meet the payment obligations under the agreements. We could be required to seek collaborators for our drug product candidates at an earlier stage than otherwise would be desirable or on terms that are less favorable than might otherwise be available or relinquish or license on unfavorable terms our rights to our drug product candidates in markets where we otherwise would seek to pursue development or commercialization ourselves. Any these events could significantly harm our business, prospects, financial condition and results of operations and cause the price of our American Depositary Shares, or ADSs, or ordinary shares to decline.

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Raising additional capital may cause dilution to our existing shareholders, restrict our operations or require us to relinquish rights to our drug product candidates or technologies.

We may seek additional funding through a combination of equity offerings, debt financings, collaborations and/or licensing arrangements. To the extent that we raise additional capital through the sale of equity or convertible debt securities, your ownership interest will be diluted, and the terms may include liquidation or other preferences that adversely affect your rights as a holder of the ADSs or the ordinary shares. The incurrence of indebtedness and/or the issuance of certain equity securities could result in increased fixed payment obligations and could also result in certain additional restrictive covenants, such as limitations on our ability to incur additional debt and/or issue additional equity, limitations on our ability to acquire or license intellectual property rights and other operating restrictions that could adversely impact our ability to conduct our business. In addition, issuance of additional equity securities, or the possibility of such issuance, may cause the market price of the ADSs or the ordinary shares to decline. In the event that we enter into collaborations and/or licensing arrangements in order to raise capital, we may be required to accept unfavorable terms, including relinquishing or licensing to a third party on unfavorable terms our rights to technologies or drug product candidates that we otherwise would seek to develop or commercialize ourselves or potentially reserve for future potential arrangements when we might be able to achieve more favorable terms.

Risks Related to Product Development, Regulatory Approval and Commercialization

We may encounter substantial delays in our clinical trials or we may fail to demonstrate safety and efficacy to the satisfaction of applicable regulatory authorities.

Before obtaining regulatory approval or marketing authorization from regulatory authorities for the sale of our drug product candidates, if at all, we must conduct extensive clinical trials to demonstrate the safety and efficacy of the drug product candidates in humans. Clinical testing is expensive, time-consuming and uncertain as to outcome. We cannot guarantee that any clinical trials will be conducted as planned or completed on schedule, if at all. A failure of one or more clinical trials can occur at any stage of testing. Events that may prevent successful or timely completion of clinical development include:

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For example, our Investigational New Drug Application, or IND, for the use of C-Cure in our planned Phase 3 clinical trial of C-Cure for the treatment of ischemic HF in the United States and Europe, or CHART-2, was initially submitted to the FDA in January 2012. This IND became effective in December 2013 for administration of the cells with Myostar, a Biologics catheter used for the injection of therapeutic agents into the heart, and manufactured by Biologics Delivery Systems Group, Cordis Corporation, a Johnson & Johnson company. Prior to initiating the trial, in August 2014, we filed an amendment to the IND requesting among other changes to the initial submission, the use of our proprietary cell injection catheter called C-Cath _ez . In January 2015, the FDA issued a clinical hold on CHART-2. Most of the clinical hold questions request clarifications on the design dossier of C-Cath _ez , while the remaining questions relate to providing updated safety information on CHART-1, defining CHART-2 stopping rules, and a request to measure troponin, a cardiac marker of injury, at day 30 post baseline procedure. We anticipate responding to the clinical hold questions in the third quarter of 2015 once all safety data from CHART-1 is available, and pending the FDA ’s lifting of the clinical hold, initiating CHART-2 during the second half of 2015. However, we cannot be certain that FDA will accept our response and lift the clinical hold.

Any inability to successfully complete pre-clinical and clinical development could result in additional costs to us or impair our ability to generate revenues from product sales, regulatory and commercialization milestones and royalties. Clinical trial delays could also shorten any periods during which we may have the exclusive right to commercialize our drug product candidates or allow our competitors to bring products to market before we do, which could impair our ability to successfully commercialize our drug product candidates and may harm our business and results of operations.

If the results of our clinical trials are inconclusive or if there are safety concerns or adverse events associated with our drug product candidates, we may:

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Our drug product candidates could potentially cause other adverse events that have not yet been predicted. As described above, any of these events could prevent us from achieving or maintaining market acceptance of our drug product candidates and impair our ability to commercialize our products if they are ultimately approved by applicable regulatory authorities.

Our drug product candidates may cause undesirable side effects or have other properties that could halt their clinical development, prevent their regulatory approval, limit their commercial potential, or result in significant negative consequences.

As with most biological drug products, use of our drug product candidates could be associated with side effects or adverse events which can vary in severity from minor reactions to death and in frequency from infrequent to prevalent. Undesirable side effects or unacceptable toxicities caused by our drug product candidates could cause us or regulatory authorities to interrupt, delay, or halt clinical trials. The FDA, EMA, or comparable foreign regulatory authorities could delay or deny approval of our drug product candidates for any or all targeted indications and negative side effects could result in a more restrictive label for any product that is approved. Side effects such as toxicity or other safety issues associated with the use of our drug product candidates could also require us or our collaborators to perform additional studies or halt development or sale of these drug product candidates.

Treatment-related side effects could also affect patient recruitment or the ability of enrolled subjects to complete the trial, or could result in potential product liability claims. In addition, these side effects may not be appropriately or timely recognized or managed by the treating medical staff. Any of these occurrences may materially and adversely harm our business, financial condition and prospects.

Additionally, if one or more of our drug product candidates receives marketing approval, and we or others later identify undesirable side effects caused by such products, including during any long-term follow-up observation period recommended or required for patients who receive treatment using our products, a number of potentially significant negative consequences could result, including:

Any of the foregoing could prevent us from achieving or maintaining market acceptance of the particular drug product candidate, if approved, and could significantly harm our business, results of operations, and prospects.

If we encounter difficulties enrolling patients in our clinical trials, our clinical development activities could be delayed or otherwise adversely affected.

The timely completion of clinical trials in accordance with their protocols depends, among other things, on our ability to enroll a sufficient number of patients who remain in the trial until its conclusion. We may experience difficulties in patient enrollment in our clinical trials for a variety of reasons, including:

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In addition, our clinical trials will compete with other clinical trials for drug product candidates that are in the same therapeutic areas as our drug product candidates, and this competition will reduce the number and types of patients available to us, because some patients who might have opted to enroll in our trials may instead opt to enroll in a trial being conducted by one of our competitors. Because the number of qualified clinical investigators is limited, we expect to conduct some of our clinical trials at the same clinical trial sites that some of our competitors use, which will reduce the number of patients who are available for our clinical trials at such clinical trial sites. Moreover, because our drug product candidates represent a departure from more commonly used methods for ischemic HF and cancer treatment, potential patients and their doctors may be inclined to use conventional therapies, rather than enroll patients in our clinical trials.

Even if we are able to enroll a sufficient number of patients in our clinical trials, delays in patient enrollment may result in increased costs or may affect the timing or outcome of our clinical trials, which could prevent completion of these trials and adversely affect our ability to advance the development of our drug product candidates.

Clinical development is a lengthy and expensive process with an uncertain outcome, and results of earlier studies and trials as well as data from any interim analysis of ongoing clinical trials may not be predictive of future trial results. Clinical failure can occur at any stage of clinical development.

Clinical testing is expensive and can take many years to complete, and its outcome is inherently uncertain. Failure can occur at any time during the clinical trial process. Although drug product candidates may demonstrate promising results in early clinical (human) trials and pre-clinical (animal) studies, they may not prove to be effective in subsequent clinical trials. For example, testing on animals may occur under different conditions than testing in humans and therefore the results of animal studies may not accurately predict human experience. Likewise, early clinical trials may not be predictive of eventual safety or effectiveness results in larger-scale pivotal clinical trials. The results of pre-clinical studies and previous clinical trials as well as data from any interim analysis of ongoing clinical trials of our drug product candidates, as well as studies and trials of other products with similar mechanisms of action to our drug product candidates, may not be predictive of the results of ongoing or future clinical trials. For example, the positive results generated in our Phase 2 clinical trial of C-Cure for the treatment of patients with ischemic HF do not ensure that our ongoing Phase 3 clinical trial of C-Cure for the treatment of patients with ischemic HF in Europe and Israel, or CHART-1, will demonstrate similar results or observations. Drug product candidates in later stages of clinical trials may fail to show the desired safety and efficacy traits despite having progressed through pre-clinical studies and earlier clinical trials. In addition to the safety and efficacy traits of any drug product candidate, clinical trial failures

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may result from a multitude of factors including flaws in trial design, dose selection, placebo effect and patient enrollment criteria. A number of companies in the pharmaceutical industry have suffered significant setbacks in advanced clinical trials due to lack of efficacy or adverse safety profiles, notwithstanding promising results in earlier trials, and it is possible that we will as well. Based upon negative or inconclusive results, we or our collaborators may decide, or regulators may require us, to conduct additional clinical trials or pre-clinical studies. In addition, data obtained from trials and studies are susceptible to varying interpretations, and regulators may not interpret our data as favorably as we do, which may delay, limit or prevent regulatory approval.

The regulatory approval processes of the FDA, EMA and other comparable regulatory authorities is lengthy, time-consuming, and inherently unpredictable, and we may experience significant delays in the clinical development and regulatory approval, if any, of our drug product candidates.

The research, testing, manufacturing, labeling, approval, selling, import, export, marketing, and distribution of drug products, including biologics, are subject to extensive regulation by the FDA, EMA and other comparable regulatory authorities. We are not permitted to market any biological drug product in the United States until we receive a Biologics License Application, or BLA, from the FDA or a marketing authorization application, or MAA, from the EMA. We have not previously submitted a BLA to the FDA, MAA to the EMA, or similar approval filings to comparable foreign authorities. A BLA must include extensive pre-clinical and clinical data and supporting information to establish that the drug product candidate is safe, pure, and potent for each desired indication. The BLA must also include significant information regarding the chemistry, manufacturing, and controls for the product, and the manufacturing facilities must complete a successful pre-license inspection. We expect the nature of our drug product candidates to create further challenges in obtaining regulatory approval. For example, the FDA and EMA have limited experience with commercial development of genetically modified T-cell therapies for cancer. The FDA may also require a panel of experts, referred to as an Advisory Committee, to deliberate on the adequacy of the safety and efficacy data to support licensure. The opinion of the Advisory Committee, although not binding, may have a significant impact on our ability to obtain licensure of the drug product candidates based on the completed clinical trials. Accordingly, the regulatory approval pathway for our drug product candidates may be uncertain, complex, expensive, and lengthy, and approval may not be obtained.

Obtaining and maintaining regulatory approval of our drug product candidates in one jurisdiction does not mean that we will be successful in obtaining regulatory approval of our drug product candidates in other jurisdictions.

If we obtain and maintain regulatory approval of our drug product candidates in one jurisdiction, such approval does not guarantee that we will be able to obtain or maintain regulatory approval in any other jurisdiction, but a failure or delay in obtaining regulatory approval in one jurisdiction may have a negative effect on the regulatory approval process in others. For example, even if the FDA grants marketing approval of a drug product candidate, comparable regulatory authorities in foreign jurisdictions must also approve the manufacturing, marketing and promotion of the drug product candidate in those countries. Approval procedures vary among jurisdictions and can involve requirements and administrative review periods different from those in the United States, including additional pre-clinical studies or clinical trials as clinical trials conducted in one jurisdiction may not be accepted by regulatory authorities in other jurisdictions. In many jurisdictions outside the United States, a drug product candidate must be approved for reimbursement before it can be approved for sale in that jurisdiction. In some cases, the price that we intend to charge for our products is also subject to approval.

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Obtaining foreign regulatory approvals and compliance with foreign regulatory requirements could result in significant delays, difficulties and costs for us and could delay or prevent the introduction of our products in certain countries. If we fail to comply with the regulatory requirements in international markets and/or to receive applicable marketing approvals, our target market will be reduced and our ability to realize the full market potential of our drug product candidates will be harmed.

A Breakthrough Therapy Designation by the FDA for our drug product candidates may not lead to a faster development or regulatory review or approval process, and it does not increase the likelihood that our drug product candidates will receive marketing approval.

We may seek a Breakthrough Therapy Designation for some of our drug product candidates. A breakthrough therapy is defined as a product that is intended, alone or in combination with one or more other products, to treat a serious or life-threatening disease or condition, and preliminary clinical evidence indicates that the product may demonstrate substantial improvement over existing therapies on one or more clinically significant endpoints, such as substantial treatment effects observed early in clinical development. For drug product candidates that have been designated as breakthrough therapies, interaction and communication between the FDA and the sponsor of the trial can help to identify the most efficient path for clinical development while minimizing the number of patients placed in ineffective control regimens. Drug product candidates designated as breakthrough therapies by the FDA are also eligible for accelerated approval.

Designation as a breakthrough therapy is within the discretion of the FDA. Accordingly, even if we believe one of our drug product candidates meets the criteria for designation as a breakthrough therapy, the FDA may disagree and instead determine not to make such designation. In any event, the receipt of a Breakthrough Therapy Designation for a drug product candidate may not result in a faster development process, review or approval compared to drugs considered for approval under conventional FDA procedures and does not assure ultimate approval by the FDA. In addition, even if one or more of our drug product candidates qualify as breakthrough therapies, the FDA may later decide that the drug product candidates no longer meet the conditions for qualification.

A Fast Track Designation by the FDA may not actually lead to a faster development or regulatory review or approval process.

We may seek Fast Track Designation for some of our drug product candidates. If a product is intended for the treatment of a serious or life-threatening condition and the product demonstrates the potential to address unmet medical needs for this condition, the product sponsor may apply for Fast Track Designation. The FDA has broad discretion whether or not to grant this designation, so even if we believe a particular drug product candidate is eligible for this designation, we cannot assure you that the FDA would decide to grant it. Even if we do receive Fast Track Designation, we may not experience a faster development process, review or approval compared to conventional FDA procedures. The FDA may withdraw Fast Track Designation if it believes that the designation is no longer supported by data from our clinical development program.

We may seek Orphan Drug Designation for some of our drug product candidates, and we may be unsuccessful or may be unable to maintain the benefits associated with Orphan Drug Designation, including the potential for market exclusivity.

As part of our business strategy, we may seek Orphan Drug Designation for some of our drug product candidates, and we may be unsuccessful. Regulatory authorities in some jurisdictions, including the United States and the European Union, may designate products for relatively small patient populations as orphan drugs. Under the Orphan Drug Act, the FDA may designate a product as an orphan drug if it is a

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product intended to treat a rare disease or condition, which is generally defined as a patient population of fewer than 200,000 individuals annually in the United States, or a patient population greater than 200,000 in the United States where there is no reasonable expectation that the cost of developing the product will be recovered from sales in the United States. In the United States, Orphan Drug Designation entitles a party to financial incentives such as opportunities for grant funding towards clinical trial costs, tax advantages and user-fee waivers.

Similarly, in the European Union, the EMA’s Committee for Orphan Medicinal Products grants Orphan Drug Designation to promote the development of products that are intended for the diagnosis, prevention or treatment of life-threatening or chronically debilitating conditions affecting not more than five in 10,000 persons in the European Union and for which no satisfactory method of diagnosis, prevention, or treatment has been authorized (or the product would be a significant benefit to those affected). Additionally, designation is granted for products intended for the diagnosis, prevention, or treatment of a life-threatening, seriously debilitating or serious and chronic condition and when, without incentives, it is unlikely that sales of the product in the European Union would be sufficient to justify the necessary investment in developing the product. In the European Union, Orphan Drug Designation entitles a party to financial incentives such as reduction of fees or fee waivers.

Generally, if a drug product candidate with an Orphan Drug Designation subsequently receives the first marketing approval for the indication for which it has such designation, the product is entitled to a period of marketing exclusivity, which precludes the EMA or the FDA from approving another marketing application for the same product and indication for that time period, except in limited circumstances. The applicable period is seven years in the United States and ten years in Europe. The European exclusivity period can be reduced to six years if a product no longer meets the criteria for Orphan Drug Designation or if the drug is sufficiently profitable so that market exclusivity is no longer justified.

Even if we obtain orphan drug exclusivity for a product, that exclusivity may not effectively protect the product from competition because different products can be approved for the same condition or the same products can be approved for different conditions. If one of our drug product candidates that receives an orphan drug designation is approved for a particular indication or use within the rare disease, the FDA may later approve the same product for additional indications or uses within that rare disease that are not protected by our exclusive approval. Even after an orphan drug is approved, the FDA can subsequently approve the same product for the same condition if the FDA concludes that the later product is clinically superior in that it is shown to be safer, more effective or makes a major contribution to patient care. In addition, a designated orphan drug may not receive orphan drug exclusivity if it is approved for a use that is broader than the indication for which it received orphan designation. Moreover, orphan drug exclusive marketing rights in the United States may be lost if the FDA later determines that the request for designation was materially defective or if the manufacturer is unable to assure sufficient quantity of the product to meet the needs of patients with the rare disease or condition or if another product with the same active moiety is determined to be safer, more effective, or represents a major contribution to patient care. Orphan Drug Designation neither shortens the development time or regulatory review time of a product nor gives the product any advantage in the regulatory review or approval process. While we intend to seek Orphan Drug Designation for some of our drug product candidates, we may never receive such designations. Even if we do receive such designations, there is no guarantee that we will enjoy the benefits of those designations.

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Even if we receive regulatory approval of our drug product candidates, we will be subject to ongoing regulatory obligations and continued regulatory review, which may result in significant additional expense and we may be subject to penalties if we fail to comply with regulatory requirements or experience unanticipated problems with our drug product candidates.

If our drug product candidates are approved, they will be subject to ongoing regulatory requirements for manufacturing, labeling, packaging, storage, advertising, promotion, sampling, record-keeping, conduct of post-marketing studies, and submission of safety, efficacy, and other post-market information, including both federal and state requirements in the United States and requirements of comparable foreign regulatory authorities.

Manufacturers and manufacturers’ facilities are required to comply with extensive FDA, and comparable foreign regulatory authority, requirements, including ensuring that quality control and manufacturing procedures conform to current Good Manufacturing Practices, or cGMP, and in certain cases Good Tissue Practices, or cGTP, regulations. As such, we and our contract manufacturers will be subject to continual review and inspections to assess compliance, to the extent applicable, with cGMP and adherence to commitments made in any BLA, other marketing application, and previous responses to inspection observations. Accordingly, we and others with whom we work must continue to expend time, money, and effort in all areas of regulatory compliance, including manufacturing, production, and quality control.

Any regulatory approvals that we receive for our drug product candidates may be subject to limitations on the approved indicated uses for which the product may be marketed or to the conditions of approval, or contain requirements for potentially costly post-marketing testing, including Phase 4 clinical trials and surveillance to monitor the safety and efficacy of the drug product candidate. The FDA may also require a REMS program as a condition of approval of our drug product candidates, which could entail requirements for long-term patient follow-up, a medication guide, physician communication plans or additional elements to ensure safe use, such as restricted distribution methods, patient registries and other risk minimization tools. In addition, if the FDA or a comparable foreign regulatory authority approves our drug product candidates, we will have to comply with requirements including submissions of safety and other post-marketing information and reports, registration, as well as continued compliance with cGMPs and cGCPs for any clinical trials that we conduct post-approval.

The FDA may impose consent decrees or withdraw approval if compliance with regulatory requirements and standards is not maintained or if problems occur after the product reaches the market. Later discovery of previously unknown problems with our drug product candidates, including adverse events of unanticipated severity or frequency, or with our third-party manufacturers or manufacturing processes, or failure to comply with regulatory requirements, may result in revisions to the approved labeling to add new safety information; imposition of post-market studies or clinical trials to assess new safety risks; or imposition of distribution restrictions or other restrictions under a REMS program. Other potential consequences include, among other things:

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The FDA strictly regulates marketing, labeling, advertising, and promotion of products that are placed on the market. Products may be promoted only for the approved indications and in accordance with approved label. The FDA and other agencies actively enforce the laws and regulations prohibiting the promotion of off-label uses, and a company that is found to have improperly promoted off-label uses may be subject to significant liability. The policies of the FDA and of other regulatory authorities may change and additional government regulations may be enacted that could prevent, limit or delay regulatory approval of our drug product candidates. We cannot predict the likelihood, nature or extent of government regulation that may arise from future legislation or administrative action, either in the United States or abroad. If we are slow or unable to adapt to changes in existing requirements or the adoption of new requirements or policies, or if we are not able to maintain regulatory compliance, we may lose any marketing approval that we may have obtained and we may not achieve or sustain profitability.

We will need to obtain FDA approval of any proposed product trade names, and any failure or delay associated with such approval may adversely impact our business.

Any trade name we intend to use for our drug product candidates will require approval from the FDA, regardless of whether we have secured a formal trademark registration from the United States Patent and Trademark Office, or USPTO. The FDA typically conducts a review of proposed product names, including an evaluation of potential for confusion with other product names and/or medication or prescribing errors. The FDA may also object to any product name we submit if it believes the name inappropriately implies medical claims. If the FDA objects to any of our proposed product names, we may be required to adopt an alternative name for our drug product candidates. If we adopt an alternative name, we would lose the benefit of our existing trademark applications for such drug product candidate, and may be required to expend significant additional resources in an effort to identify a suitable product name that would qualify under applicable trademark laws, not infringe the existing rights of third parties and be acceptable to the FDA. We may be unable to build a successful brand identity for a new trademark in a timely manner or at all, which would limit our ability to commercialize our drug product candidates.

Even if we obtain regulatory approval of our drug product candidates, the products may not gain market acceptance among physicians, patients, hospitals and others in the medical community.

Our autologous engineered-cell therapies may not become broadly accepted by physicians, patients, hospitals, and others in the medical community. Numerous factors will influence whether our drug product candidates are accepted in the market, including:

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In addition, although we are not utilizing embryonic stem cells in our drug product candidates, adverse publicity due to the ethical and social controversies surrounding the therapeutic use of such technologies, and reported side effects from any clinical trials using these technologies or the failure of such trials to demonstrate that these therapies are safe and effective may limit market acceptance our drug product candidates due to the perceived similarity between our drug product candidates and these other therapies. If our drug product candidates are approved but fail to achieve market acceptance among physicians, patients, hospitals, or others in the medical community, we will not be able to generate significant revenue.

Even if our products achieve market acceptance, we may not be able to maintain that market acceptance over time if new products or technologies are introduced that are more favorably received than our products, are more cost effective or render our products obsolete.

Coverage and reimbursement may be limited or unavailable in certain market segments for our drug product candidates, which could make it difficult for us to sell our drug product candidates profitably.

Successful sales of our drug product candidates, if approved, depend on the availability of adequate coverage and reimbursement from third-party payors. In addition, because our drug product candidates represent novel approaches to the treatment of ischemic HF and cancer, we cannot accurately estimate the potential revenue from our drug product candidates. Patients who are provided medical treatment for their conditions generally rely on third-party payors to reimburse all or part of the costs associated with their treatment. Adequate coverage and reimbursement from governmental healthcare programs, such as Medicare and Medicaid, and commercial payors are critical to new product acceptance.

Government authorities and third-party payors, such as private health insurers and health maintenance organizations, decide which drugs and treatments they will cover and the amount of reimbursement. Coverage and reimbursement by a third-party payor may depend upon a number of factors, including the third-party payor’s determination that use of a product is:

In the United States, no uniform policy of coverage and reimbursement for products exists among third-party payors. As a result, obtaining coverage and reimbursement approval of a product from a government or other third-party payor is a time-consuming and costly process that could require us to

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provide to each payor supporting scientific, clinical and cost-effectiveness data for the use of our products on a payor-by-payor basis, with no assurance that coverage and adequate reimbursement will be obtained. Even if we obtain coverage for a given product, the resulting reimbursement payment rates might not be adequate for us to achieve or sustain profitability or may require co-payments that patients find unacceptably high. Additionally, third-party payors may not cover, or provide adequate reimbursement for, long-term follow-up evaluations required following the use of our products. Patients are unlikely to use our drug product candidates unless coverage is provided and reimbursement is adequate to cover a significant portion of the cost of our drug product candidates. Because our drug product candidates have a higher cost of goods than conventional therapies, and may require long-term follow up evaluations, the risk that coverage and reimbursement rates may be inadequate for us to achieve profitability may be greater.

We intend to seek approval to market our drug product candidates in the United States, European Union, and in selected other foreign jurisdictions. If we obtain approval in one or more foreign jurisdictions for our drug product candidates, we will be subject to rules and regulations in those jurisdictions. For example, in the countries of the European Union, the pricing of biologics is subject to governmental control. In these countries, pricing negotiations with governmental authorities can take considerable time after obtaining marketing approval of a drug product candidate. In addition, market acceptance and sales of our drug product candidates will depend significantly on the availability of adequate coverage and reimbursement from third-party payors for our drug product candidates and may be affected by existing and future health care reform measures.

Healthcare legislative reform measures and constraints on national budget social security systems may have a material adverse effect on our business and results of operations.

Third-party payors, whether domestic or foreign, or governmental or private, are developing increasingly sophisticated methods of controlling healthcare costs. In both the United States and certain foreign jurisdictions, there have been a number of legislative and regulatory changes to the health care system that could impact our ability to sell our products profitably. In particular, in 2010, the Patient Protection and Affordable Care Act, as amended by the Health Care and Education Reconciliation Act of 2010, or the ACA, was enacted, which, among other things, subjected biologic products to potential competition by lower-cost biosimilars, addressed a new methodology by which rebates owed by manufacturers under the Medicaid Drug Rebate Program are calculated for drugs that are inhaled, infused, instilled, implanted or injected, increased the minimum Medicaid rebates owed by most manufacturers under the Medicaid Drug Rebate Program, extended the Medicaid Drug Rebate program to utilization of prescriptions of individuals enrolled in Medicaid managed care organizations, subjected manufacturers to new annual fees and taxes for certain branded prescription drugs, and provided incentives to programs that increase the federal government’s comparative effectiveness research. We cannot predict the full impact of the ACA on bio-pharmaceutical companies as many of the ACA reforms require the promulgation of additional detailed regulations implementing the statutory provisions which has not yet completely occurred. Further, new litigation is currently pending before the U.S. Supreme Court seeking to invalidate certain provisions of the ACA.

In addition, other legislative changes have been proposed and adopted in the United States since the ACA was enacted. In August 2011, the Budget Control Act of 2011, among other things, created measures for spending reductions by Congress. A Joint Select Committee on Deficit Reduction, tasked with recommending a targeted deficit reduction of at least $1.2 trillion for the years 2013 through 2021, was unable to reach required goals, thereby triggering the legislation’s automatic reduction to several government programs. This includes aggregate reductions of Medicare payments to providers of 2% per

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fiscal year, which went into effect in April 2013, and will remain in effect through 2024 unless additional Congressional action is taken. In January 2013, the American Taxpayer Relief Act of 2012, was signed into law, which, among other things, further reduced Medicare payments to several providers, including hospitals and cancer treatment centers, and increased the statute of limitations period for the government to recover overpayments to providers from three to five years.

There have been, and likely will continue to be, legislative and regulatory proposals at the foreign, federal and state levels directed at broadening the availability of healthcare and containing or lowering the cost of healthcare. We cannot predict the initiatives that may be adopted in the future. The continuing efforts of the government, insurance companies, managed care organizations and other payors of healthcare services to contain or reduce costs of healthcare and/or impose price controls may adversely affect:

Any denial in coverage or reduction in reimbursement from Medicare or other government programs may result in a similar denial or reduction in payments from private payors, which may adversely affect our future profitability.

Our drug product candidates are biologics, which are complex to manufacture, and we may encounter difficulties in production, particularly with respect to process development or scaling-out of our manufacturing capabilities. If we or any of our third-party manufacturers encounter such difficulties, our ability to provide supply of our drug product candidates for clinical trials or our products for patients, if approved, could be delayed or stopped, or we may be unable to maintain a commercially viable cost structure.

Our drug product candidates are biologics and the process of manufacturing our products is complex, highly-regulated and subject to multiple risks. The manufacture of our drug product candidates involves complex processes, including harvesting cells from patients, selecting and expanding certain cell types, engineering or reprogramming the cells in a certain manner to create either cardiopoietic cells or CAR T-cells, expanding the cell population to obtain the desired dose, and ultimately infusing the cells back into a patient’s body. As a result of the complexities, the cost to manufacture our drug product candidates, is higher than traditional small molecule chemical compounds, and the manufacturing process is less reliable and is more difficult to reproduce. Our manufacturing process is susceptible to product loss or failure due to logistical issues associated with the collection of blood cells, or starting material, from the patient, shipping such material to the manufacturing site, shipping the final product back to the patient, and infusing the patient with the product, manufacturing issues associated with the differences in patient starting materials, interruptions in the manufacturing process, contamination, equipment or reagent failure, improper installation or operation of equipment, vendor or operator error, inconsistency in cell growth, and variability in product characteristics. Even minor deviations from normal manufacturing processes could result in reduced production yields, product defects, and other supply disruptions. For example, we were only able to produce C-Cure for 70% of the patients that we attempted to produce drug product candidate for in our Phase 2 clinical trial. If for any reason we lose a patient’s starting material or later-developed product at any point in the process, the manufacturing process for that patient will need to be restarted and the resulting delay may adversely affect that patient’s outcome. If microbial, viral, or other contaminations are discovered in our drug product candidates or in the manufacturing facilities in which

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our drug product candidates are made, such manufacturing facilities may need to be closed for an extended period of time to investigate and remedy the contamination. Because our drug product candidates are manufactured for each particular patient, we are required to maintain a chain of identity with respect to materials as they move from the patient to the manufacturing facility, through the manufacturing process, and back to the patient. Maintaining such a chain of identity is difficult and complex, and failure to do so could result in adverse patient outcomes, loss of product, or regulatory action including withdrawal of our products from the market. Further, as drug product candidates are developed through pre-clinical to late stage clinical trials towards approval and commercialization, it is common that various aspects of the development program, such as manufacturing methods, are altered along the way in an effort to optimize processes and results. Such changes carry the risk that they will not achieve these intended objectives, and any of these changes could cause our drug product candidates to perform differently and affect the results of ongoing clinical trials or other future clinical trials.

We are currently manufacturing C-Cure for CHART-1 in our pilot manufacturing plant in Belgium. We are also planning to build a pilot manufacturing facility in the United States to reduce our overall logistical costs for CHART-2 and to allow redundancy between manufacturing sites. The cells for our ongoing Phase 1 clinical trial of CAR-NKG2D are being manufacturing at the Dana Farber Cancer Institute’s cell manufacturing facility. In the future, we plan to operate two commercial manufacturing sites, one in the United States and one in the European Union. We believe this will allow increased flexibility and reduced logistical costs and will allow for the necessary redundancy in case of site or geography-related failure. However, we are very early in the process of locating sites for these commercial manufacturing facilities and may be unsuccessful in our ability to find appropriate sites for such facilities.

Although we are working, or will be working, to develop commercially viable processes for the manufacture of our drug product candidates, doing so is a difficult and uncertain task, and there are risks associated with scaling to the level required for later-stage clinical trials and commercialization, including, among others, cost overruns, potential problems with process scale-out, process reproducibility, stability issues, lot consistency, and timely availability of reagents or raw materials. We may ultimately be unable to reduce the cost of goods for our drug product candidates to levels that will allow for an attractive return on investment if and when those drug product candidates are commercialized.

In addition, the manufacturing process that we develop for our drug product candidates is subject to FDA and foreign regulatory authority approval process, and we will need to make sure that we or our contract manufacturers, or CMOs, if any, are able to meet all FDA and foreign regulatory authority requirements on an ongoing basis. If we or our CMOs are unable to reliably produce drug product candidates to specifications acceptable to the FDA or other regulatory authorities, we may not obtain or maintain the approvals we need to commercialize such drug product candidates. Even if we obtain regulatory approval for any of our drug product candidates, there is no assurance that either we or our CMOs will be able to manufacture the approved product to specifications acceptable to the FDA or other regulatory authorities, to produce it in sufficient quantities to meet the requirements for the potential launch of the product, or to meet potential future demand. Any of these challenges could have an adverse effect on our business, financial condition, results of operations and growth prospects.

We may face competition from biosimilars, which may have a material adverse impact on the future commercial prospects of our drug product candidates.

Even if we are successful in achieving regulatory approval to commercialize a drug product candidate faster than our competitors, we may face competition from biosimilars. The Biologics Price Competition and Innovation Act of 2009, or BPCI Act, created an abbreviated approval pathway for biological products that

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are demonstrated to be biosimilar to, or interchangeable with, an FDA-approved biological product. “Biosimilarity” means that the biological product is highly similar to the reference product notwithstanding minor differences in clinically inactive components and there are no clinically meaningful differences between the biological product and the reference product in terms of safety, purity, and potency of the product. To meet the higher standard of “interchangeability,” an applicant must provide sufficient information to show biosimilarity and demonstrate that the biological product can be expected to produce the same clinical result as the reference product in any given patient and, if the biological product is administrated more than once to an individual, the risk in terms of safety or diminished efficacy of alternating or switching between the use of the biological product and the reference product is not greater than the risk of using the reference product without such alternation or switch.

A reference biological product is granted 12 years of exclusivity from the time of first licensure of the product, and the FDA will not accept an application for a biosimilar or interchangeable product based on the reference biological product until four years after first licensure. First licensure typically means the initial date the particular product at issue was licensed in the United States. This does not include a supplement for the biological product or a subsequent application by the same sponsor or manufacturer of the biological product (or licensor, predecessor in interest, or other related entity) for a change that results in a new indication, route of administration, dosing schedule, dosage form, delivery system, delivery device, or strength, unless that change is a modification to the structure of the biological product and such modification changes its safety, purity, or potency. Whether a subsequent application, if approved, warrants exclusivity as the first licensure of a biological product is determined on a case-by-case basis with data.

This data exclusivity does not prevent another company from developing a product that is highly similar to the innovative product, generating its own data, and seeking approval. Data exclusivity only assures that another company cannot rely upon the data within the application for the reference biological product to support the biosimilar product’s approval.

In the European Union, the European Commission has granted marketing authorizations for several biosimilars pursuant to a set of general and product class-specific guidelines for biosimilar approvals issued over the past few years. In the European Union, a competitor may reference data supporting approval of an innovative biological product, but will not be able do so until eight years after the time of approval of the innovative product and to get its biosimilar on the market until ten years from the aforementioned approval. This 10-year marketing exclusivity period will be extended to 11 years if, during the first eight of those ten years, the marketing authorization holder obtains an approval for one or more new therapeutic indications that bring significant clinical benefits compared with existing therapies. In addition, companies may be developing biosimilars in other countries that could compete with our products.

If competitors are able to obtain marketing approval for biosimilars referencing our products, our products may become subject to competition from such biosimilars, with the attendant competitive pressure and consequences.

We currently have no marketing and sales organization and have no experience in marketing products. If we are unable to establish marketing and sales capabilities or enter into agreements with third parties to market and sell our drug product candidates, we may not be able to generate product revenue.

We currently have no sales, marketing, or commercial product distribution capabilities and have no experience in marketing products. We intend to develop an in-house marketing organization and sales force, which will require significant capital expenditures, management resources and time. We will have

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to compete with other pharmaceutical and biotechnology companies to recruit, hire, train and retain marketing and sales personnel. If we are unable or decide not to establish internal sales, marketing and commercial distribution capabilities for any or all products we develop, we will likely pursue collaborative arrangements regarding the sales and marketing of our products. However, there can be no assurance that we will be able to establish or maintain such collaborative arrangements, or if we are able to do so, that they will have effective sales forces. Any revenue we receive will depend upon the efforts of such third parties, which may not be successful. We may have little or no control over the marketing and sales efforts of such third parties, and our revenue from product sales may be lower than if we had commercialized our drug product candidates ourselves. We also face competition in our search for third parties to assist us with the sales and marketing efforts of our drug product candidates.

There can be no assurance that we will be able to develop in-house sales and commercial distribution capabilities or establish or maintain relationships with third-party collaborators to successfully commercialize any product in the United States, the European Union, overseas, and as a result, we may not be able to generate product revenue.

We face intense competition and rapid technological change and the possibility that our competitors may develop therapies that are more advanced or effective than ours, which may adversely affect our financial condition and our ability to successfully commercialize our drug product candidates.

We face competition both in the United States and internationally, including from major multinational pharmaceutical companies, biotechnology companies and universities and other research institutions. In addition, many universities and private and public research institutes are active in our target disease areas. As of the date of this prospectus, our main competitors for C-Cure include Aldagen, Inc., Athersys, Inc., Cytori Therapeutics, Inc., Mesoblast Ltd and Vericel Corporation. As of the date of this prospectus, our main competitors for CAR-NKG2D and our other CAR T-cell product candidates include Bellicum Pharmaceuticals, Inc., bluebird bio, Inc., Cellectis S.A., Juno Therapeutics, Inc., Kite Pharma Inc., Novartis AG and Ziopharm Oncology, Inc.

Many of our competitors have substantially greater financial, technical and other resources, such as larger research and development staff and experienced marketing and manufacturing organizations. Competition may increase further as a result of advances in the commercial applicability of technologies and greater availability of capital for investment in these industries. Our competitors may succeed in developing, acquiring or licensing on an exclusive basis, products that are more effective or less costly than any drug product candidate that we may develop, or achieve earlier patent protection, regulatory approval, product commercialization and market penetration than we do. Additionally, technologies developed by our competitors may render our potential drug product candidates uneconomical or obsolete, and we may not be successful in marketing our drug product candidates against competitors.

In addition, as a result of the expiration or successful challenge of our patent rights, we could face litigation with respect to the validity and/or scope of patents relating to our competitors’ products. The availability of our competitors’ products could limit the demand, and the price we are able to charge, for any products that we may develop and commercialize.

Risks Related to our Reliance on Third Parties

Cell-based therapies rely on the availability of specialty raw materials, which may not be available to us on acceptable terms or at all.

Engineered-cell therapies require many specialty raw materials, some of which are manufactured by small companies with limited resources and experience to support a commercial product. The suppliers may be

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ill-equipped to support our needs, especially in non-routine circumstances like an FDA inspection or medical crisis, such as widespread contamination. We also do not have contracts with many of these suppliers, and may not be able to contract with them on acceptable terms or at all. Accordingly, we may experience delays in receiving key raw materials to support clinical or commercial manufacturing.

In addition, some raw materials are currently available from a single supplier, or a small number of suppliers. We cannot be sure that these suppliers will remain in business, or that they will not be purchased by one of our competitors or another company that is not interested in continuing to produce these materials for our intended purpose.

We rely on third parties to conduct, supervise and monitor our clinical trials. If these third parties do not successfully carry out their contractual duties or meet expected deadlines, we may not be able to obtain regulatory approval for or commercialize our drug product candidates and our business could be substantially harmed.

We rely on CROs and clinical trial sites to ensure our clinical trials are conducted properly and on time. While we will have agreements governing their activities, we will have limited influence over their actual performance. We will control only certain aspects of our CROs’ activities. Nevertheless, we will be responsible for ensuring that each of our clinical trials is conducted in accordance with the applicable protocol, legal, regulatory and scientific standards, and our reliance on the CROs does not relieve us of our regulatory responsibilities.

We and our CROs are required to comply with the GCPs for conducting, recording and reporting the results of clinical trials to assure that the data and reported results are credible and accurate and that the rights, integrity and confidentiality of clinical trial participants are protected. The FDA, the Competent Authorities of the Member States of the EEA, and comparable foreign regulatory authorities, enforce these GCPs through periodic inspections of trial sponsors, principal investigators and clinical trial sites. If we or our CROs fail to comply with applicable GCPs, the clinical data generated in our future clinical trials may be deemed unreliable and the FDA, the EMA, or other foreign regulatory authorities may require us to perform additional clinical trials before approving any marketing applications. Upon inspection, the FDA may determine that our clinical trials did not comply with GCPs. In addition, our future clinical trials will require a sufficient number of test subjects to evaluate the safety and effectiveness of our drug product candidates. Accordingly, if our CROs fail to comply with these regulations or fail to recruit a sufficient number of patients, we may be required to repeat such clinical trials, which would delay the regulatory approval process.

Our CROs are not our employees, and we are therefore unable to directly monitor whether or not they devote sufficient time and resources to our clinical programs. These CROs may also have relationships with other commercial entities, including our competitors, for whom they may also be conducting clinical trials or other product development activities that could harm our competitive position. If our CROs do not successfully carry out their contractual duties or obligations, fail to meet expected deadlines, or if the quality or accuracy of the clinical data they obtain is compromised due to the failure to adhere to our clinical protocols or regulatory requirements, or for any other reasons, our clinical trials may be extended, delayed or terminated, and we may not be able to obtain regulatory approval for, or successfully commercialize, our drug product candidates. If any such event were to occur, our financial results and the commercial prospects for our drug product candidates would be harmed, our costs could increase, and our ability to generate revenues could be delayed.

If any of our relationships with these third-party CROs terminate, we may not be able to enter into arrangements with alternative CROs or to do so on commercially reasonable terms. Further, switching or

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adding additional CROs involves additional costs and requires management time and focus. In addition, there is a natural transition period when a new CRO commences work. As a result, delays occur, which could materially impact our ability to meet our desired clinical development timelines. Though we carefully manage our relationships with our CROs, there can be no assurance that we will not encounter challenges or delays in the future or that these delays or challenges will not have a material adverse impact on our business, financial condition and prospects.

Risks Related to Intellectual Property

We depend on intellectual property licensed from third parties and termination of any of these licenses could result in the loss of significant rights, which would harm our business.

We are dependent on patents, know-how, and proprietary technology, both our own and licensed from others. We license technology from the Mayo Foundation for Medical Education and Research, or the Mayo Clinic, and the Trustees of Dartmouth College, or Dartmouth College. The Mayo Clinic may terminate our license agreement with them, or the Mayo License, on a product-by-product basis or licensed invention-by-licensed invention basis if we default in making payment when due and payable or under other circumstances specified in the Mayo License, subject to 120 days’ prior written notice and opportunity to cure. The Mayo Clinic may also terminate the Mayo License if we deliberately make false statements in reports delivered to the Mayo Clinic. Further, the Mayo Clinic may terminate the Mayo License immediately for our insolvency or bankruptcy. Dartmouth College may terminate either our 2010 license or 2014 license, if we fail to meet a milestone within the specified time period, unless we pay the corresponding milestone payment. Dartmouth College may terminate either the 2010 license or 2014 license in the event we default or breach any of the provisions of the applicable license, subject to 30 days’ prior notice and opportunity to cure. In addition, each of the 2010 license and 2014 license automatically terminates in the event we become insolvent, make an assignment for the benefit of creditors or file, or have filed against us, a petition in bankruptcy. Furthermore, Dartmouth College may terminate our 2010 license, after April 30, 2024, if we fail to meet the specified minimum net sales obligations for any year, unless we pay to Dartmouth College the royalty we would otherwise be obligated to pay had we met such minimum net sales obligation. Any termination of these licenses could result in the loss of significant rights and could harm our ability to commercialize our drug product candidates. Disputes may also arise between us and our licensors regarding intellectual property subject to a license agreement, including those relating to:

If disputes over intellectual property that we have licensed prevent or impair our ability to maintain our current licensing arrangements on acceptable terms, we may be unable to successfully develop and

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commercialize the affected drug product candidates. We are generally also subject to all of the same risks with respect to protection of intellectual property that we license as we are for intellectual property that we own, which are described below. If we or our licensors fail to adequately protect this intellectual property, our ability to commercialize our products could suffer.

We could be unsuccessful in obtaining or maintaining adequate patent protection for one or more of our drug product candidates.

The patent application process is expensive and time-consuming, and we and our current or future licensors and licensees may not be able to apply for or prosecute patents on certain aspects of our drug product candidates or deliver technologies at a reasonable cost, in a timely fashion, or at all. It is also possible that we or our current licensors, or any future licensors or licensees, will fail to identify patentable aspects of inventions made in the course of development and commercialization activities before it is too late to obtain patent protection on them. Therefore, our patents and applications may not be prosecuted and enforced in a manner consistent with the best interests of our business. It is possible that defects of form in the preparation or filing of our patents or patent applications may exist, or may arise in the future, such as with respect to proper priority claims, inventorship, claim scope or patent term adjustments. Under our existing license agreements with the Mayo Foundation for Medical Education and Research and the Trustees of Dartmouth College, we have the right, but not the obligation, to enforce our licensed patents. If our current licensors, or any future licensors or licensees, are not fully cooperative or disagree with us as to the prosecution, maintenance or enforcement of any patent rights, such patent rights could be compromised and we might not be able to prevent third parties from making, using, and selling competing products. If there are material defects in the form or preparation of our patents or patent applications, such patents or applications may be invalid and unenforceable. Moreover, our competitors may independently develop equivalent knowledge, methods, and know-how. Any of these outcomes could impair our ability to prevent competition from third parties, which may have an adverse impact on our business, financial condition and operating results.

We currently have issued patents and patent applications directed to our drug product candidates and medical devices, and we anticipate that we will file additional patent applications both in the United States and in other countries, as appropriate. However, we cannot predict:

We cannot be certain, however, that the claims in our pending patent applications will be considered patentable by the USPTO or by patent offices in foreign countries, or that the claims in any of our issued patents will be considered valid and enforceable by courts in the United States or foreign countries.

The strength of patents in the biotechnology and pharmaceutical field can be uncertain, and evaluating the scope of such patents involves complex legal and scientific analyses. The patent applications that we own or in-license may fail to result in issued patents with claims that cover our drug product candidates or uses thereof in the United States or in other foreign countries. Even if the patents do successfully issue, third parties may challenge the validity, enforceability, or scope thereof, which may result in such patents

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being narrowed, invalidated, or held unenforceable. Furthermore, even if they are unchallenged, our patents and patent applications may not adequately protect our intellectual property or prevent others from designing their products to avoid being covered by our claims. If the breadth or strength of protection provided by the patent applications we hold with respect to our drug product candidates is threatened, this could dissuade companies from collaborating with us to develop, and could threaten our ability to commercialize, our drug product candidates. Further, because patent applications in the United States and most other countries are confidential for a period of time after filing, we cannot be certain that we were the first to file any patent application related to our drug product candidates. Furthermore, for U.S. applications in which all claims are entitled to a priority date before March 16, 2013, an interference proceeding can be provoked by a third party or instituted by the USPTO to determine who was the first to invent any of the subject matter covered by the patent claims of our applications. For U.S. applications containing a claim not entitled to priority before March 16, 2013, there is a greater level of uncertainty in the patent law in view of the passage of the America Invents Act, which brought into effect significant changes to the U.S. patent laws, including new procedures for challenging pending patent applications and issued patents.

Patents have a limited lifespan. In the United States, the natural expiration of a patent is generally 20 years after it is filed. Various extensions may be available; however the life of a patent, and the protection it affords, is limited. Further, the extensive period of time between patent filing and regulatory approval for a drug product candidate limits the time during which we can market a drug product candidate under patent protection, which may particularly affect the profitability of our early-stage drug product candidates. If we encounter delays in our clinical trials, the period of time during which we could market our drug product candidates under patent protection would be reduced. Without patent protection for our drug product candidates, we may be open to competition from biosimilar versions of our drug product candidates.

We may not be able to protect our intellectual property rights throughout the world.

Filing, prosecuting and defending patents on drug product candidates in all countries throughout the world would be prohibitively expensive, and our intellectual property rights in some countries outside the United States can be less extensive than those in the United States. In addition, the laws of some foreign countries do not protect intellectual property rights to the same extent as federal and state laws in the United States. Consequently, we may not be able to prevent third parties from practicing our inventions in all countries outside the United States, or from selling or importing products made using our inventions in and into the United States or other jurisdictions. Competitors may use our technologies in jurisdictions where we have not obtained patent protection to develop their own products and further, may export otherwise infringing products to territories where we have patent protection, but enforcement is not as strong as that in the United States. These products may compete with our products and our patents or other intellectual property rights may not be effective or sufficient to prevent them from competing.

Many companies have encountered significant problems in protecting and defending intellectual property rights in foreign jurisdictions. The legal systems of certain countries, particularly certain developing countries, do not favor the enforcement of patents, trade secrets and other intellectual property protection, particularly those relating to biotechnology products, which could make it difficult for us to stop the infringement of our patents or marketing of competing products in violation of our proprietary rights generally. For example, an April 2014 report from the Office of the United States Trade Representative identified a number of countries, including India and China, where challenges to the procurement and enforcement of patent rights have been reported. Several countries, including India and China, have been listed in the report every year since 1989. Proceedings to enforce our patent rights in foreign jurisdictions could result in substantial costs and divert our efforts and attention from other aspects of our business,

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could put our patents at risk of being invalidated or interpreted narrowly and our patent applications at risk of not issuing and could provoke third parties to assert claims against us. We may not prevail in any lawsuits that we initiate and the damages or other remedies awarded, if any, may not be commercially meaningful. Accordingly, our efforts to enforce our intellectual property rights around the world may be inadequate to obtain a significant commercial advantage from the intellectual property that we develop or license.

Confidentiality agreements with employees and third parties may not prevent unauthorized disclosure of trade secrets and other proprietary information.

In addition to the protection afforded by patents, we seek to rely on trade secret protection and confidentiality agreements to protect proprietary know-how that is not patentable or that we elect not to patent, processes for which patents are difficult to enforce, and any other elements of our product discovery and development processes that involve proprietary know-how, information, or technology that is not covered by patents. Trade secrets, however, may be difficult to protect. We seek to protect our proprietary processes, in part, by entering into confidentiality agreements with our employees, consultants, outside scientific advisors, contractors and collaborators. Although we use reasonable efforts to protect our trade secrets, our employees, consultants, outside scientific advisors, contractors, and collaborators might intentionally or inadvertently disclose our trade secret information to competitors. In addition, competitors may otherwise gain access to our trade secrets or independently develop substantially equivalent information and techniques. Furthermore, the laws of some foreign countries do not protect proprietary rights to the same extent or in the same manner as the laws of the United States. As a result, we may encounter significant problems in protecting and defending our intellectual property both in the United States and abroad. If we are unable to prevent unauthorized material disclosure of our intellectual property to third parties, or misappropriation of our intellectual property by third parties, we will not be able to establish or maintain a competitive advantage in our market, which could materially adversely affect our business, operating results and financial condition.

Third-party claims of intellectual property infringement against us or our collaborators may prevent or delay our product discovery and development efforts.

Our commercial success depends in part on our avoiding infringement of the patents and proprietary rights of third parties. There is a substantial amount of litigation involving patents and other intellectual property rights in the biotechnology and pharmaceutical industries, as well as administrative proceedings for challenging patents, including interference, derivation, and reexamination proceedings before the USPTO or oppositions and other comparable proceedings in foreign jurisdictions. Recently, due to changes in U.S. law referred to as patent reform, new procedures including inter partes review and post-grant review have been implemented. This reform adds uncertainty to the possibility of challenge to our patents in the future.

Numerous U.S. and foreign issued patents and pending patent applications owned by third parties exist in the fields in which we are developing our drug product candidates. As the biotechnology and pharmaceutical industries expand and more patents are issued, the risk increases that our drug product candidates may give rise to claims of infringement of the patent rights of others.

Although we have conducted analyses of the patent landscape with respect to our drug product candidates, and based on these analyses, we believe that we will be able to commercialize our drug product candidates, third parties may nonetheless assert that we infringe their patents, or that we are otherwise employing their proprietary technology without authorization, and may sue us. There may be third-party patents of which we are currently unaware with claims to compositions, formulations,

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methods of manufacture, or methods of use or treatment that cover our drug product candidates. Because patent applications can take many years to issue, there may be currently pending patent applications that may later result in issued patents that our drug product candidates may infringe. In addition, third parties may obtain patents in the future and claim that use of our technologies or the manufacture, use, or sale of our drug product candidates infringes upon these patents. If any such third-party patents were held by a court of competent jurisdiction to cover our technologies or drug product candidates, the holders of any such patents may be able to block our ability to commercialize the applicable drug product candidate unless we obtain a license under the applicable patents, or until such patents expire or are finally determined to be held invalid or unenforceable. Such a license may not be available on commercially reasonable terms or at all. If we are unable to obtain a necessary license to a third-party patent on commercially reasonable terms, our ability to commercialize our drug product candidates may be impaired or delayed, which could in turn significantly harm our business.

Third parties asserting their patent rights against us may seek and obtain injunctive or other equitable relief, which could effectively block our ability to further develop and commercialize our drug product candidates. Defense of these claims, regardless of their merit, would involve substantial litigation expense and would be a substantial diversion of management and other employee resources from our business, and may impact our reputation. In the event of a successful claim of infringement against us, we may have to pay substantial damages, including treble damages and attorneys’ fees for willful infringement, obtain one or more licenses from third parties, pay royalties, or redesign our infringing products, which may be impossible or require substantial time and monetary expenditure. In that event, we would be unable to further develop and commercialize our drug product candidates, which could harm our business significantly.

We may be involved in lawsuits to protect or enforce our patents or the patents of our licensors, which could be expensive, time-consuming, and unsuccessful.

Competitors may infringe our patents or the patents of our licensors. To cease such infringement or unauthorized use, we may be required to file patent infringement claims, which can be expensive and time-consuming. In addition, in an infringement proceeding or a declaratory judgment action against us, a court may decide that one or more of our patents is not valid or is unenforceable, or may refuse to stop the other party from using the technology at issue on the grounds that our patents do not cover the technology in question. An adverse result in any litigation or defense proceeding could put one or more of our patents at risk of being invalidated, held unenforceable, interpreted narrowly, or amended such that they do not cover our drug product candidates. Such results could also put our pending patent applications at risk of not issuing. Defense of these claims, regardless of their merit, would involve substantial litigation expense and would be a substantial diversion of employee resources from our business. Interference or derivation proceedings provoked by third parties or brought by the USPTO may be necessary to determine the priority of inventions with respect to, or the correct inventorship of, our patents or patent applications or those of our licensors. An unfavorable outcome could result in a loss of our current patent rights and could require us to cease using the related technology or to attempt to license rights to it from the prevailing party. Our business could be harmed if the prevailing party does not offer us a license on commercially reasonable terms. Litigation, interference, or derivation proceedings may result in a decision adverse to our interests and, even if we are successful, may result in substantial costs and distract our management and other employees.

Furthermore, because of the substantial amount of discovery required in connection with intellectual property litigation, there is a risk that some of our confidential information could be compromised by disclosure during this type of litigation. In addition, there could be public announcements of the results

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of hearings, motions or other interim proceedings or developments. If securities analysts or investors perceive these results to be negative, it could have a substantial adverse effect on the price of our ordinary shares.

Issued patents covering our drug product candidates could be found invalid or unenforceable if challenged in court or before the USPTO or comparable foreign authority.

If we or one of our licensing partners initiate legal proceedings against a third party to enforce a patent covering one of our drug product candidates, the defendant could counterclaim that the patent covering our drug product candidate is invalid or unenforceable. In patent litigation in the United States, defendant counterclaims alleging invalidity or unenforceability are commonplace, and there are numerous grounds upon which a third party can assert invalidity or unenforceability of a patent. Third parties may also raise similar claims before administrative bodies in the United States or abroad, even outside the context of litigation. Such mechanisms include re-examination, inter partes review, post-grant review, and equivalent proceedings in foreign jurisdictions, such as opposition or derivation proceedings. Such proceedings could result in revocation or amendment to our patents in such a way that they no longer cover and protect our drug product candidates. The outcome following legal assertions of invalidity and unenforceability is unpredictable. With respect to the validity of our patents, for example, we cannot be certain that there is no invalidating prior art of which we, our patent counsel, and the patent examiner were unaware during prosecution. If a defendant were to prevail on a legal assertion of invalidity and/or unenforceability, we would lose at least part, and perhaps all, of the patent protection on our drug product candidates. Such a loss of patent protection could have a material adverse impact on our business.

Changes in U.S. patent law could diminish the value of patents in general, thereby impairing our ability to protect our products.

As is the case with other biopharmaceutical companies, our success is heavily dependent on intellectual property, particularly patents. Obtaining and enforcing patents in the biopharmaceutical industry involves, both technological and legal complexity, and is therefore costly, time-consuming, and inherently uncertain. Numerous recent changes to the patent laws and proposed changes to the rules of the USPTO may have a significant impact on our ability to protect our technology and enforce our intellectual property rights. For example, the Leahy-Smith America Invents Act, or AIA, enacted in 2011 involves significant changes in patent legislation. An important change introduced by the AIA is that, as of March 16, 2013, the United States transitioned to a ‘‘first-to-file’’ system for deciding which party should be granted a patent when two or more patent applications are filed by different parties claiming the same invention. A third party that files a patent application in the USPTO after that date but before us could therefore be awarded a patent covering an invention of ours even if we had made the invention before it was made by the third party. This will require us to be cognizant going forward of the time from invention to filing of a patent application.

Among some of the other changes introduced by the AIA are changes that limit where a patentee may file a patent infringement suit and provide opportunities for third parties to challenge any issued patent in the USPTO. This applies to all of our U.S. patents, even those issued before March 16, 2013. Because of a lower evidentiary standard in USPTO proceedings compared to the evidentiary standard in United States federal court necessary to invalidate a patent claim, a third party could potentially provide evidence in a USPTO proceeding sufficient for the USPTO to hold a claim invalid even though the same evidence would be insufficient to invalidate the claim if first presented in a district court action. Accordingly, a third party may attempt to use the USPTO procedures to invalidate our patent claims that would not have been invalidated if first challenged by the third party as a defendant in a district court action.

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In addition, recent court rulings in cases such as Association for Molecular Pathology v. Myriad Genetics, Inc. (Myriad I); BRCA1- & BRCA2-Based Hereditary Cancer Test Patent Litig.,(Myriad II); and Promega Corp. v. Life Technologies Corp. have narrowed the scope of patent protection available in certain circumstances and weakened the rights of patent owners in certain situations. In addition to increasing uncertainty with regard to our ability to obtain patents in the future, this combination of events has created uncertainty with respect to the value of patents once obtained. Depending on decisions by the U.S. Congress, the federal courts, and the USPTO, the laws and regulations governing patents could change in unpredictable ways that would weaken our ability to obtain new patents or to enforce our existing patents and patents that we might obtain in the future. For example, in a recent case, Assoc. for Molecular Pathology v. Myriad Genetics, Inc., the U.S. Supreme Court held that certain claims to naturally-occurring substances are not patentable. Although we do not believe that any of the patents owned or licensed by us will be found invalid based on this decision, we cannot predict how future decisions by the courts, the U.S. Congress, or the USPTO may impact the value of our patents.

We may be subject to claims that our employees, consultants, or independent contractors have wrongfully used or disclosed confidential information of third parties.

We have received confidential and proprietary information from third parties. In addition, we employ individuals who were previously employed at other biotechnology or pharmaceutical companies. We may be subject to claims that we or our employees, consultants, or independent contractors have inadvertently or otherwise used or disclosed confidential information of these third parties or our employees’ former employers. Litigation may be necessary to defend against these claims. Even if we are successful in defending against these claims, litigation could result in substantial cost and be a distraction to our management and employees.

Obtaining and maintaining our patent protection depends on compliance with various procedural, document submission, fee payment, and other requirements imposed by governmental patent agencies, and our patent protection could be reduced or eliminated for non-compliance with these requirements.

Periodic maintenance fees on any issued patent are due to be paid to the USPTO and foreign patent agencies in several stages over the lifetime of the patent. The USPTO and various foreign governmental patent agencies require compliance with a number of procedural, documentary, fee payment, and other similar provisions during the patent application process. Although an inadvertent lapse can in many cases be cured by payment of a late fee or by other means in accordance with the applicable rules, there are situations in which noncompliance can result in abandonment or lapse of the patent or patent application, resulting in partial or complete loss of patent rights in the relevant jurisdiction. Noncompliance events that could result in abandonment or lapse of a patent or patent application include failure to respond to official actions within prescribed time limits, non-payment of fees, and failure to properly legalize and submit formal documents. In any such event, our competitors might be able to enter the market, which would have a material adverse effect on our business.

Risks Related to Our Organization, Structure and Operation

Our future results will suffer if we do not effectively manage our expanded operations as a result of our recent acquisition of OnCyte.

We obtained access to our CAR T-cell drug product candidates and related technology, including technology licensed from Dartmouth College, in January 2015, through our acquisition of OnCyte, LLC, or OnCyte, from Celdara Medical, LLC, a privately-held U.S. biotechnology company. Our acquisition of OnCyte significantly changed the composition of our operations, markets and drug product candidate

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mix. Our future success depends, in part, on our ability to address these changes, and, where necessary, to attract and retain new personnel that possess the requisite skills called for by these changes.

Our failure to adequately address the financial, operational or legal risks of the OnCyte acquisition, or any future acquisitions, license arrangements, other strategic transactions could harm our business. Financial aspects of these transactions that could alter our financial position, reported operating results or ADS or ordinary share price include:

Operational risks that could harm our existing operations or prevent realization of anticipated benefits from these transactions include:

Our future success depends, in part, upon our ability to manage our expansion opportunities. Integrating new operations into our existing business in an efficient and timely manner, successfully monitoring our operations, costs, regulatory compliance and customer relationships, and maintaining other necessary internal controls pose substantial challenges for us. As a result, we cannot assure you that our expansion or acquisition opportunities will be successful, or that we will realize our expected operating efficiencies, cost savings, revenue enhancements, synergies or other benefits.

We are highly dependent on our Chief Executive Officer and members of our executive management team, and if we are not successful in motivating and retaining highly qualified personnel, we may not be able to successfully implement our business strategy.

Our ability to compete in the highly competitive biotechnology and pharmaceutical industries depends upon our ability to attract, motivate and retain highly qualified managerial, scientific and medical

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personnel. We are highly dependent on members of our executive management team, particularly our chief executive officer, Christian Homsy. We do not maintain “key man” insurance on the life of Christian Homsy, or the lives of any of our other employees. The loss of the services of any members of our executive management team, and our inability to find suitable replacements, could result in delays in product development and harm our business.

Competition for skilled personnel in the biotechnology and pharmaceutical industries is intense and the turnover rate can be high, which may limit our ability to hire and retain highly qualified personnel on acceptable terms or at all.

To induce valuable employees to remain at our company, in addition to salary and cash incentives, we have provided warrants that vest over time. The value to employees of these equity grants that vest over time may be significantly affected by movements in our share price that are beyond our control, and may at any time be insufficient to counteract more lucrative offers from other companies.

We will need to grow the size and capabilities of our organization, and we may experience difficulties in managing this growth.

As of March 26, 2015, we had 82 full-time and three part-time employees. As our drug product candidates move into later stage clinical development and towards commercialization, we must add a significant number of additional managerial, operational, sales, marketing, financial, and other personnel. Future growth will impose significant added responsibilities on members of management, including:

Our future financial performance and our ability to commercialize our drug product candidates will depend, in part, on our ability to effectively manage any future growth, and our management may also have to divert a disproportionate amount of its attention away from day-to-day activities in order to devote a substantial amount of time to managing these growth activities.

If we are not able to effectively expand our organization by hiring new employees and expanding our groups of consultants and contractors, we may not be able to successfully implement the tasks necessary to further develop and commercialize our drug product candidates and, accordingly, may not achieve our research, development, and commercialization goals.

If we engage in future acquisitions or strategic partnerships, this may increase our capital requirements, dilute our shareholders, cause us to incur debt or assume contingent liabilities, and subject us to other risks.

We may evaluate various acquisitions and strategic partnerships, including licensing or acquiring complementary products, intellectual property rights, technologies, or businesses. Any potential acquisition or strategic partnership may entail numerous risks, including:

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In addition, if we undertake acquisitions, we may issue dilutive securities, assume or incur debt obligations, incur large one-time expenses and acquire intangible assets that could result in significant future amortization expense. Moreover, we may not be able to locate suitable acquisition opportunities and this inability could impair our ability to grow or obtain access to technology or products that may be important to the development of our business.

If we fail to comply with environmental, health and safety laws and regulations, we could become subject to fines or penalties or incur costs that could have a material adverse effect on the success of our business.

We are subject to numerous environmental, health and safety laws and regulations, including those governing laboratory procedures and the handling, use, storage, treatment and disposal of hazardous materials and wastes. Our operations involve the use of hazardous and flammable materials, including chemicals and biological materials. Our operations also produce hazardous waste products. We generally contract with third parties for the disposal of these materials and wastes. We cannot eliminate the risk of contamination or injury from these materials, which could cause an interruption of our commercialization efforts, research and development efforts and business operations, environmental damage resulting in costly clean-up and liabilities under applicable laws and regulations governing the use, storage, handling and disposal of these materials and specified waste products. Although we believe that the safety procedures utilized by our third-party manufacturers for handling and disposing of these materials generally comply with the standards prescribed by these laws and regulations, we cannot guarantee that this is the case or eliminate the risk of accidental contamination or injury from these materials. In such an event, we may be held liable for any resulting damages and such liability could exceed our resources and state or federal or other applicable authorities may curtail our use of certain materials and/or interrupt our business operations. Furthermore, environmental laws and regulations are complex, change frequently and have tended to become more stringent. We cannot predict the impact of such changes and cannot be certain of our future compliance. In addition, we may incur substantial costs in order to comply with current or future environmental, health and safety laws and regulations. These current or future laws and regulations may impair our research, development or production efforts. Failure to comply with these laws and regulations also may result in substantial fines, penalties or other sanctions. We do not currently carry biological or hazardous waste insurance coverage.

Although we maintain workers’ compensation insurance to cover us for costs and expenses we may incur due to injuries to our employees resulting from the use of hazardous materials or other work-related injuries, this insurance may not provide adequate coverage against potential liabilities.

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Risks from the improper conduct of employees, agents, contractors, consultants or collaborators could adversely affect our reputation and our business, prospects, operating results, and financial condition.

We cannot ensure that our compliance controls, policies, and procedures will in every instance protect us from acts committed by our employees, agents, contractors, or collaborators that would violate the laws or regulations of the jurisdictions in which we operate, including, without limitation, healthcare, employment, foreign corrupt practices, environmental, competition, and patient privacy and other privacy laws and regulations. Such improper actions could subject us to civil or criminal investigations, and monetary and injunctive penalties, and could adversely impact our ability to conduct business, operating results, and reputation. In particular, our business activities may be subject to the Foreign Corrupt Practices Act, or FCPA, and similar anti-bribery or anti-corruption laws, regulations or rules of other countries in which we operate, including the U.K. Bribery Act. The FCPA generally prohibits offering, promising, giving, or authorizing others to give anything of value, either directly or indirectly, to a non-U.S. government official in order to influence official action, or otherwise obtain or retain business. The FCPA also requires public companies to make and keep books and records that accurately and fairly reflect the transactions of the corporation and to devise and maintain an adequate system of internal accounting controls. Our business is heavily regulated and therefore involves significant interaction with public officials, including officials of non-U.S. governments.

Additionally, in many other countries, the health care providers who prescribe pharmaceuticals are employed by their government, and the purchasers of pharmaceuticals are government entities; therefore, our dealings with these prescribers and purchasers are subject to regulation under the FCPA. Recently the Securities and Exchange Commission, or SEC, and Department of Justice have increased their FCPA enforcement activities with respect to pharmaceutical companies. There is no certainty that all of our employees, agents, contractors, consultants or collaborators, or those of our affiliates, will comply with all applicable laws and regulations, particularly given the high level of complexity of these laws. Violations of these laws and regulations could result in fines, criminal sanctions against us, our officers, or our employees, the closing down of our facilities, requirements to obtain export licenses, cessation of business activities in sanctioned countries, implementation of compliance programs, and prohibitions on the conduct of our business. Any such violations could include prohibitions on our ability to offer our products in one or more countries and could materially damage our reputation, our brand, our international expansion efforts, our ability to attract and retain employees, and our business, prospects, operating results, and financial condition.

Our relationships with health care professionals, customers, independent contractors, consultants and third-party payors may be subject, directly or indirectly, to applicable anti-kickback laws, fraud and abuse laws, false claims laws, health information privacy and security laws, transparency laws and other healthcare laws and regulations, which could expose us to penalties, and could result in contractual damages, reputational harm, administrative burdens and diminished profits and future earnings.

Our arrangements with health care professionals, customers, independent contractors, consultants and third-party payors may expose us to broadly applicable fraud and abuse and other healthcare laws and regulations that may constrain the business or financial arrangements and relationships.

In addition, we may be subject to health information privacy and security regulation of the European Union, the United States and other jurisdictions in which we conduct our business. For example, the laws that may affect our ability to operate include:

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Efforts to ensure that our business arrangements with third parties will comply with applicable healthcare laws and regulations may involve substantial costs. It is possible that governmental authorities will conclude that our business practices may not comply with current or future statutes, regulations or case law involving applicable fraud and abuse or other healthcare laws and regulations. If our operations are found to be in violation of any of these laws or any other governmental regulations that may apply to us, we may be subject to significant civil, criminal and administrative penalties, including, without limitation, damages, fines, imprisonment, exclusion from participation in government funded healthcare programs, such as Medicare and Medicaid, and the curtailment or restructuring of our operations or other sanctions. If any of the physicians or other healthcare providers or entities with whom we expect to do business is found to be not in compliance with applicable laws and regulations, it may be subject to criminal, civil or administrative sanctions, including exclusions from participation in government funded healthcare programs.

Failure to build our finance infrastructure and improve our accounting systems and controls could impair our ability to comply with the financial reporting and internal controls requirements for publicly traded companies.

As a public company, we will operate in an increasingly demanding regulatory environment that requires us to comply with, among things, the Sarbanes-Oxley Act of 2002, and related rules and regulations of the Securities and Exchange Commission’s substantial disclosure requirements, accelerated reporting

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requirements and complex accounting rules. Company responsibilities required by the Sarbanes-Oxley Act include establishing corporate oversight and adequate internal control over financial reporting and disclosure controls and procedures. Effective internal controls are necessary for us to produce reliable financial reports and are important to help prevent financial fraud.

We have limited accounting personnel and other resources to address our internal controls and procedures. Our independent registered public accounting firm has not conducted an audit of our internal control over financial reporting. However, in connection with the reaudit of our consolidated financial statements as of and for year ended December 31, 2013 and audit of our consolidated financial statements as of and for the year ended December 31, 2014, we identified three material weaknesses in our internal control over financial reporting. A material weakness is a deficiency, or combination of deficiencies, such that there is reasonable possibility that a material misstatement of our annual or interim consolidated financial statements will not be prevented or detected on a timely basis by our employees. The material weaknesses identified were related to a lack of:

As described in Note 2.36 of our consolidated financial statements included elsewhere in this prospectus, we have restated our consolidated financial statements as of and for the year ended December 31, 2013 as a result of errors in the accounting treatment of shareholders convertible loans and share-based payments. We believe that the material weaknesses identified contributed to the restatement.

We have taken several remedial actions to address these material weaknesses, which are described under “Management’s discussion and analysis of financial condition and results of operations – Internal control over financial reporting.”

Furthermore, we believe it is possible that if we had performed a formal assessment of our internal control over financial reporting, or if our independent registered public accounting firm had performed an audit of our internal control over financial reporting, other material weaknesses may have been identified. Upon the completion of the global offering, Section 404 of the Sarbanes-Oxley Act, or Section 404, will require that we include a report of management on our internal control over financial reporting in our annual report on Form 20-F beginning with our annual report for the fiscal year ending December 31, 2016. However, until we cease to be an “emerging growth company,” as that term is defined in the Jumpstart Our Business Startups Act of 2012, or the JOBS Act, our independent registered public accounting firm will not be required to attest to and report on the effectiveness of our internal control over financial reporting. This may increase the risk that deficiencies in our internal control over financial reporting will go undetected and may make it more difficult for investors and securities analysts to evaluate our company.

Our management may conclude that our internal control over financial reporting is not effective. Moreover, even if our management concludes that our internal control over financial reporting is effective, our independent registered public accounting firm, after conducting its own independent testing, may issue a report that is qualified if it is not satisfied with our internal controls or the level at which our controls are documented, designed, operated or reviewed, or if it interprets the relevant requirements differently from us. In addition, after we become a public company, our reporting

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obligations may place a significant strain on our management, operational and financial resources and systems for the foreseeable future. We may be unable to timely complete our evaluation, testing and any required remediation.

During the course of documenting and testing our internal control procedures in order to satisfy the requirements of Section 404, we may identify other material weaknesses in our internal control over financial reporting. In addition, if we fail to maintain the adequacy of our internal control over financial reporting, as these standards are modified, supplemented or amended from time to time, we may not be able to conclude on an ongoing basis that we have effective internal control over financial reporting in accordance with Section 404. If we fail to achieve and maintain an effective internal control environment, we could experience material misstatements in our consolidated financial statements and fail to meet our reporting obligations, which would likely cause investors to lose confidence in our reported financial information. This could in turn limit our access to capital markets, harm our results of operations, and lead to a decline in the trading price of our ordinary shares. Additionally, ineffective internal control over financial reporting could expose us to increased risk of fraud or misuse of corporate assets and subject us to potential delisting from The NASDAQ Global Market, or NASDAQ, regulatory investigations and civil or criminal sanctions. We may also be required to restate our financial statements for prior periods.

Our business and operations would suffer in the event of system failures.

Despite the implementation of security measures, our internal computer systems and those of our current and future CROs and other contractors and consultants are vulnerable to damage from computer viruses, unauthorized access, natural disasters, terrorism, war and telecommunication and electrical failures. While we have not experienced any such material system failure, accident or security breach to date, if such an event were to occur and cause interruptions in our operations, it could result in a material disruption of our development programs and our business operations. For example, the loss of clinical trial data from completed or future clinical trials could result in delays in our regulatory approval efforts and significantly increase our costs to recover or reproduce the data. To the extent that any disruption or security breach were to result in a loss of, or damage to, our data or applications, or inappropriate disclosure of confidential or proprietary information, we could incur liability and the further development and commercialization of our product candidates could be delayed.

Business disruptions could seriously harm our future revenue and financial condition and increase our costs and expenses.

Our operations, and those of our third-party research institution collaborators, CROs, CMOs, suppliers, and other contractors and consultants, could be subject to earthquakes, power shortages, telecommunications failures, water shortages, floods, hurricanes, typhoons, fires, extreme weather conditions, medical epidemics, and other natural or man-made disasters or business interruptions. The occurrence of any of these business disruptions could seriously harm our operations and financial condition and increase our costs and expenses. Damage or extended periods of interruption to our corporate, development or research facilities due to fire, natural disaster, power loss, communications failure, unauthorized entry or other events could cause us to cease or delay development of some or all of our drug product candidates. Although we maintain property damage and business interruption insurance coverage on these facilities, our insurance might not cover all losses under such circumstances and our business may be seriously harmed by such delays and interruption.

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If product liability lawsuits are brought against us, we may incur substantial liabilities and may be required to limit commercialization of our drug product candidates.

We face an inherent risk of product liability as a result of the clinical testing of our drug product candidates and will face an even greater risk if we commercialize any products. For example, we may be sued if our drug product candidates cause or are perceived to cause injury or are found to be otherwise unsuitable during clinical testing, manufacturing, marketing or sale. Any such product liability claims may include allegations of defects in manufacturing, defects in design, a failure to warn of dangers inherent in the product, negligence, strict liability or a breach of warranties. Claims could also be asserted under state consumer protection acts. If we cannot successfully defend ourselves against product liability claims, we may incur substantial liabilities or be required to limit commercialization of our drug product candidates. Even successful defense would require significant financial and management resources. Regardless of the merits or eventual outcome, liability claims may result in:

Our inability to obtain sufficient product liability insurance at an acceptable cost to protect against potential product liability claims could prevent or inhibit the commercialization of products we develop, alone or with collaborators. Although we currently carry €100,000 of clinical trial insurance, the amount of such insurance coverage may not be adequate, we may be unable to maintain such insurance, or we may not be able to obtain additional or replacement insurance at a reasonable cost, if at all. Our insurance policies may also have various exclusions, and we may be subject to a product liability claim for which we have no coverage. We may have to pay any amounts awarded by a court or negotiated in a settlement that exceed our coverage limitations or that are not covered by our insurance, and we may not have, or be able to obtain, sufficient capital to pay such amounts. Even if our agreements with any future corporate collaborators entitle us to indemnification against losses, such indemnification may not be available or adequate should any claim arise.

Our international operations subject us to various risks, and our failure to manage these risks could adversely affect our results of operations.

We face significant operational risks as a result of doing business internationally, such as:

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We are subject to certain covenants as a result of certain non-dilutive financial support we have received to date.

We have received non-dilutive financial support totaling €18.7 million as of December 31, 2014, to support various research programs from the Walloon Region, or the Region. The support has been granted in the form of recoverable cash advances, or RCAs, and subsidies.

In the event we decide to exploit any discoveries or products from the research funded by under an RCA, the relevant RCA becomes refundable, otherwise the RCA is not refundable. We own the intellectual property rights which result from the research programs partially funded by the Region, unless we decide not to exploit, or cease to exploit, the results of the research in which case the results and intellectual property rights are transferred to the Region. Subject to certain exceptions, however, we cannot grant to third parties, by way of license or otherwise, any right to use the results without the prior consent of the Region. We also need the consent of the Region to transfer an intellectual property right resulting from the research programs or a transfer or license of a prototype or installation. Obtaining such consent from the Region could give rise to a review of the applicable financial terms. The RCAs also contain provisions prohibiting us from conducting research for any other person which would fall within the scope of a research program of one of the RCAs. Most RCAs provide that this prohibition is applicable during the research phase and the decision phase but a number of RCAs extend it beyond these phases.

Subsidies received from the Region are dedicated to funding research programs and patent applications and are not refundable. We own the intellectual property rights which result from the research programs or with regard to a patent covered by a subsidy. Subject to certain exceptions, however, we cannot grant to third parties, by way of license, transfer or otherwise, any right to use the patents or research results without the prior consent of the Region. In addition, certain subsidies require that we exploit the patent in the countries where the protection was granted and to make an industrial use of the underlying invention. In case of bankruptcy, liquidation or dissolution, the rights to the patents covered by the patent subsidies will be assumed by the Region by operation of law unless the subsidy is reimbursed. Furthermore, we would lose our qualification as a small or medium-sized enterprise, the patent subsidies will terminate and no additional expenses will be covered by such patent subsidies.

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We may be exposed to significant foreign exchange risk.

We incur portions of our expenses, and may in the future derive revenues, in currencies other than the euro, in particular, the U.S. dollar. As a result, we are exposed to foreign currency exchange risk as our results of operations and cash flows are subject to fluctuations in foreign currency exchange rates. We currently do not engage in hedging transactions to protect against uncertainty in future exchange rates between particular foreign currencies and the euro. Therefore, for example, an increase in the value of the euro against the U.S. dollar could be expected to have a negative impact on our revenue and earnings growth as U.S. dollar revenue and earnings, if any, would be translated into euros at a reduced value. We cannot predict the impact of foreign currency fluctuations, and foreign currency fluctuations in the future may adversely affect our financial condition, results of operations and cash flows.

The requirements of being a U.S. public company may strain our resources and divert management’s attention.

We will be required to comply with various corporate governance and financial reporting requirements under the Sarbanes-Oxley Act of 2002, the Securities and Exchange Act of 1934, as amended, or the Exchange Act, and the rules and regulations adopted by the Securities and Exchange Commission and the Public Corporation Accounting Oversight Board. Further, compliance with various regulatory reporting requires significant commitments of time from our management and our directors, which reduces the time available for the performance of their other responsibilities. Our failure to track and comply with the various rules may materially adversely affect our reputation, ability to obtain the necessary certifications to financial statements, lead to additional regulatory enforcement actions, and could adversely affect the value of the ADSs or the ordinary shares.

The investment of our cash and cash equivalents may be subject to risks that may cause losses and affect the liquidity of these investments.

As of December 31, 2014, we had cash and cash equivalents of €27.6 million and short term investments of €2.7 million. We historically have invested substantially all of our available cash and cash equivalents in corporate bank accounts. Pending their use in our business, we intend to invest the net proceeds of the global offering in investments that may include corporate bonds, commercial paper, certificates of deposit and money market funds. These investments may be subject to general credit, liquidity, and market and interest rate risks. We may realize losses in the fair value of these investments or a complete loss of these investments, which would have a negative effect on our financial statements.

Risks Related to the Global Offering and Ownership of the ADSs

There has been no prior active market for the ADSs and an active and liquid market for the ADSs may fail to develop, which could harm the market price of the ADSs.

Prior to the global offering, while our ordinary shares have been traded on Euronext Brussels and Euronext Paris since July 5, 2013, there has been no active public market for the ADSs in the United States. Although we anticipate the ADSs being approved for listing on NASDAQ, an active trading market for the ADSs may never develop or be sustained following the global offering. The initial public offering price of the ADSs will be based on and determined through negotiations between us and the underwriters. This initial public offering price may not be indicative of the market price of the ADSs after the global offering. In the absence of an active trading market for the ADSs, investors may not be able to sell their ADSs at or above the initial public offering price or at the time that they would like to sell. The market price of the ADSs could be subject to wide fluctuations in response to many risk factors listed in this section, and others beyond our control, including:

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These and other market and industry factors may cause the market price and demand for the ADSs to fluctuate substantially, regardless of our actual operating performance, which may limit or prevent investors from readily selling their ADSs and may otherwise negatively affect the liquidity of our ADSs shares. In addition, the stock market in general, and biotechnology and biopharmaceutical companies in particular, have experienced extreme price and volume fluctuations that have often been unrelated or disproportionate to the operating performance of these companies.

Fluctuations in the exchange rate between the U.S. dollar and the euro may increase the risk of holding the ADSs.

Our shares currently trade on Euronext Brussels and Euronext Paris in euros, while the ADSs will trade on NASDAQ in U.S. dollars. Fluctuations in the exchange rate between the U.S. dollar and the euro may result in differences between the value of the ADSs and the value of our ordinary shares, which may result in heavy trading by investors seeking to exploit such differences. In addition, as a result of fluctuations in the exchange rate between the U.S. dollar and the euro, the U.S. dollar equivalent of the proceeds that a holder of the ADSs would receive upon the sale in Belgium of any ordinary shares withdrawn from the depositary upon calculation of the corresponding ADSs and the U.S. dollar equivalent of any cash dividends paid in euros on our ordinary shares represented by the ADSs could also decline.

Holders of the ADSs are not treated as shareholders of our company.

By participating in the U.S. offering you will become a holder of ADSs with underlying shares in a Belgian public limited liability company. Holders of the ADSs are not treated as shareholders of our company, unless they cancel the ADSs and withdraw our ordinary shares underlying the ADSs. The depositary (or its nominee) is the shareholder of the ordinary shares underlying the ADSs. Holders of ADSs therefore do not have any rights as shareholders of our company, other than the rights that they have pursuant to the deposit agreement.

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We have broad discretion in the use of the net proceeds from the global offering and may not use them effectively.

Our management will have broad discretion in the application of the net proceeds that we receive from the global offering, including applications for working capital, possible acquisitions and other general corporate purposes, and we may spend or invest these proceeds in a way with which our shareholders disagree. The failure by our management to apply these funds effectively could harm our business and financial condition. Pending their use, we may invest the net proceeds from the global offering in a manner that does not produce income or that loses value. These investments may not yield a favorable return to our investors.

If securities or industry analysts do not publish research or publish inaccurate research or unfavorable research about our business, the price of the ordinary shares and the ADSs and trading volume could decline.

The trading market for the ordinary shares and the ADSs depends in part on the research and reports that securities or industry analysts publish about us or our business. If no or few securities or industry analysts cover our company, the trading price for the ordinary shares and the ADSs would be negatively impacted. If one or more of the analysts who covers us downgrades the ordinary shares or the ADSs or publishes incorrect or unfavorable research about our business, the price of the ordinary shares and the ADSs would likely decline. If one or more of these analysts ceases coverage of our company or fails to publish reports on us regularly, or downgrades the ordinary shares or the ADSs, demand for the ADSs and ordinary shares could decrease, which could cause the price of the ADSs and ordinary shares or trading volume to decline.

We have no present intention to pay dividends on our ordinary shares in the foreseeable future and, consequently, your only opportunity to achieve a return on your investment during that time is if the price of the ADSs or the ordinary shares increases.

We have no present intention to pay dividends in the foreseeable future. Any recommendation by our board of directors to pay dividends will depend on many factors, including our financial condition (including losses carried-forward), results of operations, legal requirements and other factors. Furthermore, pursuant to Belgian law, the calculation of amounts available for distribution to shareholders, as dividends or otherwise, must be determined on the basis of our non-consolidated statutory accounts prepared in accordance with Belgian accounting rules. In addition, in accordance with Belgian law and our articles of association, we must allocate each year an amount of at least 5% of our annual net profit under our non-consolidated statutory accounts to a legal reserve until the reserve equals 10% of our share capital. Therefore, we are unlikely to pay dividends or other distributions in the foreseeable future. If the price of the ADSs or the ordinary shares declines before we pay dividends, you will incur a loss on your investment, without the likelihood that this loss will be offset in part or at all by potential future cash dividends.

Our shareholders residing in countries other than Belgium may be subject to double withholding taxation with respect to dividends or other distributions made by us.

Any dividends or other distributions we make to shareholders will, in principle, be subject to withholding tax in Belgium at a rate of 25%, except for shareholders which qualify for an exemption of withholding tax such as, among others, qualifying pension funds or a company qualifying as a parent company within the meaning of the Council Directive (90/435/EEC) July 23, 1990, known as the Parent-Subsidiary Directive, or that qualify for a lower withholding tax rate or an exemption by virtue of a tax treaty. Various conditions may apply and shareholders residing in countries other than Belgium are advised to consult their advisers regarding the tax consequences of dividends or other distributions made by us. Our shareholders residing in countries other than Belgium may not be able to credit the amount of such withholding tax to any tax due on such dividends or other distributions in any other country than

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Belgium. As a result, such shareholders may be subject to double taxation in respect of such dividends or other distributions. Belgium and the United States have concluded a double tax treaty concerning the avoidance of double taxation, or the U.S.-Belgium Tax Treaty. The U.S.-Belgium Tax Treaty reduces the applicability of Belgian withholding tax to 15%, 5% or 0% for U.S. taxpayers, provided that the U.S. taxpayer meets the limitation of benefits conditions imposed by the U.S.-Belgium Tax Treaty. The Belgian withholding tax is generally reduced to 15% under the U.S.-Belgium Tax Treaty. The 5% withholding tax applies in case where the U.S. shareholder is a company which holds at least 10% of the shares in the company. A 0% Belgian withholding tax applies when the shareholder is a company which has held at least 10% of the shares in the company for at least 12 months, or is, subject to certain conditions, a U.S. pension fund. The U.S. shareholders are encouraged to consult their own tax advisers to determine whether they can invoke the benefits and meet the limitation of benefits conditions as imposed by the U.S.-Belgium Tax Treaty.

We believe that we were a passive foreign investment company for our 2014 taxable year, and expect that we may be a passive foreign investment company in other future taxable years. U.S. holders of the ADSs may suffer adverse tax consequences if we are characterized as a passive foreign investment company.

Generally, if, for any taxable year, at least 75% of our gross income is passive income, or at least 50% of the value of our assets is attributable to assets that produce passive income or are held for the production of passive income, including cash, we would be characterized as a passive foreign investment company, or PFIC, for U.S. federal income tax purposes. For purposes of these tests, passive income includes dividends, interest, and gains from the sale or exchange of investment property and rents and royalties other than rents and royalties which are received from unrelated parties in connection with the active conduct of a trade or business. If we are characterized as a PFIC, U.S. holders of the ADSs may suffer adverse tax consequences, including having gains realized on the sale of the ADSs treated as ordinary income, rather than capital gain, the loss of the preferential rate applicable to dividends received on the ADSs by individuals who are U.S. holders, and having interest charges apply to distributions by us and the proceeds of sales of the ADSs. See “Material income tax considerations—Certain Material U.S. Federal Income Tax Considerations to U.S. Holders—Passive Foreign Investment Company Considerations.”

Our status as a PFIC will depend on the composition of our income and the composition and value of

our assets (which, if we are not a “controlled foreign corporation” under Section 957(a) of the Code or

we are publicly traded for the entire year being tested, may be determined in large part by reference to

the market value of the ADSs and ordinary shares, which may be volatile) from time to time. Our status

may also depend, in part, on how quickly we utilize the cash proceeds from the global offering in our business.

We believe we were a PFIC for our 2014 taxable year, and with respect to our 2015 taxable year and possibly other taxable years, we expect that we will be a PFIC based upon the expected value of our assets, including any goodwill, and the expected composition of our income and assets. However, our status as a PFIC is a fact intensive determination made on an annual basis and we cannot provide any assurances regarding our PFIC status for the current or future taxable years.

If you purchase the ADSs in the U.S. offering or ordinary shares in the European private placement, you will experience substantial and immediate dilution.

If you purchase the ADSs in the U.S. offering or ordinary shares in the European private placement, you will experience substantial and immediate dilution of $53.63 (€60.48) per ADS/ordinary share in the net tangible book value after giving effect to the global offering at an assumed public offering price of $70.98 (€62.94) per ADS or per ordinary share, the closing price of our ordinary shares on Euronext Brussels on June 12, 2015, because the price that you pay will be substantially greater than the net tangible book value per ADS or per ordinary share that you acquire. This dilution is due in large part to the fact that our earlier

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investors paid substantially less than the public offering price when they purchased their ordinary shares. You will experience additional dilution upon exercise of any outstanding warrants to subscribe for newly issued ordinary shares under our equity incentive plans (i.e., our warrant plans), or if we otherwise issue additional shares below the public offering price. For a further description of the dilution that you will experience immediately after the global offering, see the section of this prospectus titled “Dilution.”

Future sales of ordinary shares or ADSs by existing shareholders could depress the market price of the ADSs and the ordinary shares.

If our existing shareholders sell, or indicate an intent to sell, substantial amounts of ordinary shares or ADSs in the public market after the 90-day contractual lock-up and other legal restrictions on resale discussed in this prospectus lapse, the trading price of the ADSs and the ordinary shares could decline significantly and could decline below the public offering price. Upon completion of the global offering, we will have outstanding ordinary shares, approximately 4,037,675 of which are subject to the 90-day contractual lock-up referred to above. The representatives of the underwriters may permit us, our directors and members of our management team to sell shares prior to the expiration of the lock-up agreements. See “Underwriting.” After the lock-up agreements pertaining to the global offering expire, and based on the number of ordinary shares outstanding upon completion of the global offering, additional shares will be eligible for sale in the public market, all of which shares are held by directors and members of the management team and will be subject to volume limitations under Rule 144 under the Securities Act of 1933, as amended, or the Securities Act. In addition, the ordinary shares subject to outstanding warrants under our equity incentive plans and the shares reserved for future issuance under our equity incentive plans will become eligible for sale in the public market in the future, subject to certain legal and contractual limitations.

Following the global offering, we intend to file one or more registration statements with the SEC covering ordinary shares available for future issuance under our equity incentive plans. Upon effectiveness of such registration statements, any shares subsequently issued under such plans will be eligible for sale in the public market, except to the extent that they are restricted by the lock-up agreements referred to above and subject to compliance with Rule 144 in the case of our affiliates. Sales of a large number of the shares issued under these plans in the public market could have an adverse effect on the market price of the ADSs and the ordinary shares. See the section of this prospectus titled “Shares and ADSs available for future sale” for a more detailed description of sales that may occur in the future. If these additional shares or ADSs are sold, or if it is perceived that they will be sold, in the public market, the trading price of the ADSs and the ordinary shares could decline substantially.

We are a Belgian public limited liability company, and shareholders of our company may have different and in some cases more limited shareholder rights than shareholders of a U.S. listed corporation.

We are a public limited liability company incorporated under the laws of Belgium. Our corporate affairs are governed by Belgian corporate and securities law. The rights provided to our shareholders under Belgian corporate law and our articles of association differ in certain respects from the rights that you would typically enjoy as a shareholder of a U.S. corporation under applicable U.S. federal and state laws. Under Belgian corporate law, other than certain information that we must make public and except in certain limited circumstances, our shareholders may not ask for an inspection of our corporate records, while under Delaware corporate law any shareholder, irrespective of the size of its shareholdings, may do so. Shareholders of a Belgian corporation have more limited rights to initiate a derivative action, a remedy typically available to shareholders of U.S. companies, in order to enforce a right of our Company, in case we fail to enforce such right ourselves.

A liability action can be instituted for our account by one or more of our shareholders who, individually or together, hold securities representing at least 1.0% of the votes or a part of the capital worth at least

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€1.25 million and have not approved of the discharge from liability that was granted to the directors. If the court orders the directors to pay damages, they are due to us, though the amounts advanced by the minority shareholders (for example attorney’s fees) are to be reimbursed by us. If the action is disallowed, the minority shareholders may be ordered to pay the costs, and, should there be grounds therefor, to pay damages to the directors, for example for having conducted provocative and reckless legal proceedings.

In addition, a majority of our shareholders present or represented at our meeting of shareholders may release a director from any claim of liability we may have, provided that the financial position of the company is accurately reflected in the annual accounts. This includes a release from liability for any acts of the directors beyond their statutory powers or in breach of the Belgian Company Code, provided that the relevant acts were specifically mentioned in the convening notice to the meeting of shareholders deliberating on the discharge. In contrast, most U.S. federal and state laws prohibit a company or its shareholders from releasing a director from liability altogether if he or she has acted in bad faith or has breached his or her duty of loyalty to the company. Finally, Belgian corporate law does not provide any form of appraisal rights in the case of a business combination. See “Description of share capital.” As a result of these differences between Belgian corporate law and our articles of association, on the one hand, and the U.S. federal and state laws, on the other hand, in certain instances, you could receive less protection as an ADS holder of our company than you would as a shareholder of a listed U.S. company.

Takeover provisions in the national law of Belgium may make a takeover difficult.

Public takeover bids on our shares and other voting securities, such as warrants or convertible bonds, if any, are subject to the Belgian Act of April 1, 2007 on public takeover bids, as amended and implemented by the Belgian Royal Decree of April 27, 2007, or Royal Decree, and to the supervision by the Belgian Financial Services and Markets Authority, or FSMA. Public takeover bids must be made for all of our voting securities, as well as for all other securities that entitle the holders thereof to the subscription to, the acquisition of or the conversion into voting securities. Prior to making a bid, a bidder must issue and disseminate a prospectus, which must be approved by the FSMA. The bidder must also obtain approval of the relevant competition authorities, where such approval is legally required for the acquisition of our company. The Belgian Act of April 1, 2007 provides that a mandatory bid will be required to be launched for all of our outstanding shares and securities giving access to ordinary shares if a person, as a result of its own acquisition or the acquisition by persons acting in concert with it or by persons acting on their account, directly or indirectly holds more than 30% of the voting securities in a company that has its registered office in Belgium and of which at least part of the voting securities are traded on a regulated market or on a multilateral trading facility designated by the Royal Decree. The mere fact of exceeding the relevant threshold through the acquisition of one or more shares will give rise to a mandatory bid, irrespective of whether or not the price paid in the relevant transaction exceeds the current market price.

There are several provisions of Belgian company law and certain other provisions of Belgian law, such as the obligation to disclose important shareholdings and merger control, that may apply to us and which may make an unfriendly tender offer, merger, change in management or other change in control, more difficult. These provisions could discourage potential takeover attempts that third parties may consider and thus deprive the shareholders of the opportunity to sell their shares at a premium (which is typically offered in the framework of a takeover bid).

You will not have the same voting rights as the holders of our ordinary shares and may not receive voting materials in time to be able to exercise your right to vote.

Holders of ADSs may exercise voting rights with respect to the ordinary shares represented by the ADSs only in accordance with the provisions of the deposit agreement. The deposit agreement provides that,

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upon receipt of notice of any meeting of holders of our ordinary shares, the depositary will fix a record date for the determination of ADS holders who shall be entitled to give instructions for the exercise of voting rights. Upon timely receipt of notice from us, if we so request, the depositary shall distribute to the holders as of the record date (1) the notice of the meeting or solicitation of consent or proxy sent by us and (2) a statement as to the manner in which instructions may be given by the holders. You may instruct the depositary of your ADSs to vote the ordinary shares underlying your ADSs. Otherwise, you will not be able to exercise your right to vote, unless you withdraw the ordinary shares underlying the ADSs you hold. However, you may not know about the meeting far enough in advance to withdraw those ordinary shares. We cannot guarantee you that you will receive the voting materials in time to ensure that you can instruct the depositary to vote your ordinary shares or to withdraw your ordinary shares so that you can vote them yourself. In addition, the depositary and its agents are not responsible for failing to carry out voting instructions or for the manner of carrying out voting instructions. This means that you may not be able to exercise your right to vote, and there may be nothing you can do if the ordinary shares underlying your ADSs are not voted as you requested.

You may be subject to limitations on the transfer of your ADSs and the withdrawal of the underlying ordinary shares.

Your ADSs are transferable on the books of the depositary. However, the depositary may close its books at any time or from time to time when it deems expedient in connection with the performance of its duties. The depositary may refuse to deliver, transfer or register transfers of your ADSs generally when our books or the books of the depositary are closed, or at any time if we or the depositary think it is advisable to do so because of any requirement of law, government or governmental body, or under any provision of the deposit agreement, or for any other reason, subject to your right to cancel your ADSs and withdraw the underlying ordinary shares. Temporary delays in the cancellation of your ADSs and withdrawal of the underlying ordinary shares may arise because the depositary has closed its transfer books or we have closed our transfer books, the transfer of ordinary shares is blocked to permit voting at a shareholders’ meeting or we are paying a dividend on our ordinary shares.

In addition, you may not be able to cancel your ADSs and withdraw the underlying ordinary shares when you owe money for fees, taxes and similar charges and when it is necessary to prohibit withdrawals in order to comply with any laws or governmental regulations that apply to ADSs or to the withdrawal of ordinary shares or other deposited securities. See “Description of American Depositary Shares—Your Right to Receive the Shares Underlying Your ADSs.”

We are an “emerging growth company” and are availing ourselves of reduced disclosure requirements applicable to emerging growth companies, which could make the ADSs or the ordinary shares less attractive to investors.

We are an “emerging growth company,” as defined in the JOBS Act, and we intend to take advantage of certain exemptions from various reporting requirements that are applicable to other public companies that are not “emerging growth companies” including not being required to comply with the auditor attestation requirements of Section 404(b) of the Sarbanes-Oxley Act, reduced disclosure obligations regarding executive compensation and exemptions from the requirements of holding a nonbinding advisory vote on executive compensation and shareholder approval of any golden parachute payments not previously approved. We cannot predict if investors will find the ADSs or the ordinary shares less attractive because we may rely on these exemptions. If some investors find the ADSs or the ordinary shares less attractive as a result, there may be a less active trading market for the ADSs or the ordinary shares and the price of the ADSs or the ordinary shares may be more volatile. We may take advantage of these reporting exemptions until we are no longer an emerging growth company. We would cease to be an emerging growth company upon the earliest to occur of (1) the last day of the fiscal year in

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which we have more than $1.0 billion in annual revenue; (2) the date we qualify as a “large accelerated filer,” with at least $700 million of equity securities held by non-affiliates; (3) the issuance, in any three-year period, by our company of more than $1.0 billion in non-convertible debt securities held by non-affiliates; and (4) the last day of the fiscal year ending after the fifth anniversary of our U.S. initial public offering. We may choose to take advantage of some but not all of these exemptions.

Even after we no longer qualify as an emerging growth company, we may still qualify as a “smaller reporting company” which would allow us to take advantage of many of the same exemptions from disclosure requirements, including not being required to comply with the auditor attestation requirements of Section 404 of the Sarbanes-Oxley Act and reduced disclosure obligations regarding executive compensation. We cannot predict if investors will find our ordinary shares less attractive because we may rely on these exemptions. If some investors find our ordinary shares less attractive as a result, there may be a less active trading market for our ordinary shares and our share price may be more volatile.

As a foreign private issuer, we are exempt from a number of rules under the U.S. securities laws and are permitted to file less information with the SEC than a U.S. company. This may limit the information available to holders of ADSs or ordinary shares.

We are a “foreign private issuer,” as defined in the SEC’s rules and regulations and, consequently, we are not subject to all of the disclosure requirements applicable to public companies organized within the United States. For example, we are exempt from certain rules under the Exchange Act, that regulate disclosure obligations and procedural requirements related to the solicitation of proxies, consents or authorizations applicable to a security registered under the Exchange Act, including the U.S. proxy rules under Section 14 of the Exchange Act. In addition, our officers and directors are exempt from the reporting and “short-swing” profit recovery provisions of Section 16 of the Exchange Act and related rules with respect to their purchases and sales of our securities. Moreover, while we currently make annual and semi-annual filings with respect to our listing on Euronext Brussels and Euronext Paris, we will not be required to file periodic reports and financial statements with the SEC as frequently or as promptly as U.S. domestic issuers and will not be required to file quarterly reports on Form 10-Q or current reports on Form 8-K under the Exchange Act. Accordingly, there will be less publicly available information concerning our company than there would be if we were not a foreign private issuer.

As a foreign private issuer, we are permitted to adopt certain home country practices in relation to corporate governance matters that differ significantly from NASDAQ corporate governance listing standards. These practices may afford less protection to shareholders than they would enjoy if we complied fully with corporate governance listing standards.

As a foreign private issuer listed on NASDAQ, we will be subject to corporate governance listing standards. However, rules permit a foreign private issuer like us to follow the corporate governance practices of its home country. Certain corporate governance practices in Belgium, which is our home country, may differ significantly from corporate governance listing standards. For example, neither the corporate laws of Belgium nor our articles of association require a majority of our directors to be independent and we could include non-independent directors as members of our nomination and remuneration committee, and our independent directors would not necessarily hold regularly scheduled meetings at which only independent directors are present. Currently, we intend to follow home country practice to the maximum extent possible. Therefore, our shareholders may be afforded less protection than they otherwise would have under corporate governance listing standards applicable to U.S. domestic issuers. See “Management.”

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We may lose our foreign private issuer status in the future, which could result in significant additional cost and expense.

While we currently qualify as a foreign private issuer, the determination of foreign private issuer status is made annually on the last business day of an issuer’s most recently completed second fiscal quarter and, accordingly, the next determination will be made with respect to us on June 30, 2016. In the future, we would lose our foreign private issuer status if we to fail to meet the requirements necessary to maintain our foreign private issuer status as of the relevant determination date. For example, if more than 50% of our securities are held by U.S. residents and more than 50% of the members of our executive management team or members of our board of directors are residents or citizens of the United States, we could lose our foreign private issuer status.

The regulatory and compliance costs to us under U.S. securities laws as a U.S. domestic issuer may be significantly more than costs we incur as a foreign private issuer. If we are not a foreign private issuer, we will be required to file periodic reports and registration statements on U.S. domestic issuer forms with the SEC, which are more detailed and extensive in certain respects than the forms available to a foreign private issuer. We would be required under current SEC rules to prepare our financial statements in accordance with U.S. generally accepted accounting principles, or U.S. GAAP, rather than IFRS, and modify certain of our policies to comply with corporate governance practices associated with U.S. domestic issuers. Such conversion of our financial statements to U.S. GAAP will involve significant time and cost. In addition, we may lose our ability to rely upon exemptions from certain corporate governance requirements on U.S. stock exchanges that are available to foreign private issuers such as the ones described above and exemptions from procedural requirements related to the solicitation of proxies.

It may be difficult for investors outside Belgium to serve process on, or enforce foreign judgments against, us or our directors and senior management.

We are a Belgian public limited liability company. Less than a majority of the members of our board of directors and members of our executive management team are residents of the United States. All or a substantial portion of the assets of such non-resident persons and most of our assets are located outside the United States. As a result, it may not be possible for investors to effect service of process upon such persons or on us or to enforce against them or us a judgment obtained in U.S. courts. Original actions or actions for the enforcement of judgments of U.S. courts relating to the civil liability provisions of the federal or state securities laws of the United States are not directly enforceable in Belgium.

The United States and Belgium do not currently have a multilateral or bilateral treaty providing for reciprocal recognition and enforcement of judgments, other than arbitral awards, in civil and commercial matters. In order for a final judgment for the payment of money rendered by U.S. courts based on civil liability to produce any effect on Belgian soil, it is accordingly required that this judgment be recognized or be declared enforceable by a Belgian court in accordance with Articles 22 to 25 of the 2004 Belgian Code of Private International Law. Recognition or enforcement does not imply a review of the merits of the case and is irrespective of any reciprocity requirement. A U.S. judgment will, however, not be recognized or declared enforceable in Belgium if it infringes upon one or more of the grounds for refusal that are exhaustively listed in Article 25 of the Belgian Code of Private International Law. Actions for the enforcement of judgments of U.S. courts might be successful only if the Belgian court confirms the substantive correctness of the judgment of the U.S. court and is satisfied that:

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In addition to recognition or enforcement, a judgment by a federal or state court in the United States against us may also serve as evidence in a similar action in a Belgian court if it meets the conditions required for the authenticity of judgments according to the law of the state where it was rendered. The findings of a federal or state court in the United States will not, however, be taken into account to the extent they appear incompatible with Belgian public policy.

After the completion of the global offering, we may be at an increased risk of securities class action litigation.

Historically, securities class action litigation has often been brought against a company following a decline in the market price of its securities. This risk is especially relevant for us because biotechnology and biopharmaceutical companies have experienced significant share price volatility in recent years. If we were to be sued, it could result in substantial costs and a diversion of management’s attention and resources, which could harm our business.

We were subject to an investigation by the Belgian Financial Services and Markets Authority.

The FSMA opened an investigation against us on April 22, 2014. Such investigation was related to whether we had failed to timely disclose inside information to the market in relation to the IND clearance from the FDA for CHART-2 received on December 26, 2013 and reported on January 9, 2014. In April 2015, we notified the FSMA of our agreement to settle its investigation by paying the proposed settlement amount of €175,000. Although such settlement did not provide for any admission of guilt on our part, the fact that we have entered into a settlement with the FSMA could cause investors to have a negative perception of our governance structure, which would have a material adverse effect on our business. Further, any future allegations (based on facts and circumstances) that we failed to comply with applicable securities laws, whether or not true, may subject us to fines, claims and/or sanctions, which could impair our ability to offer our securities or restrict trading in our securities. The occurrence of any of the foregoing could have a material adverse effect on the trading price of our securities and our business.

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Forward-looking statements

This prospectus, particularly the sections of this prospectus titled “Prospectus summary,” “Risk factors,” “Management’s discussion and analysis of financial condition and results of operations” and “Business,” contains forward-looking statements. All statements other than present and historical facts and conditions contained in this prospectus, including statements regarding our future results of operations and financial positions, business strategy, plans and our objectives for future operations, are forward-looking statements. When used in this prospectus, the words “anticipate,” “believe,” “can,” “could,” “estimate,” “expect,” “intend,” “is designed to,” “may,” “might,” “plan,” “potential,” “predict,” “objective,” “should,” or the negative of these and similar expressions identify forward-looking statements. Forward-looking statements include, but are not limited to, statements about:

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You should refer to the section of this prospectus titled “Risk factors” for a discussion of important factors that may cause our actual results to differ materially from those expressed or implied by our forward-looking statements. As a result of these factors, we cannot assure you that the forward-looking statements in this prospectus will prove to be accurate. Furthermore, if our forward-looking statements prove to be inaccurate, the inaccuracy may be material. In light of the significant uncertainties in these forward-looking statements, you should not regard these statements as a representation or warranty by us or any other person that we will achieve our objectives and plans in any specified time frame or at all. We undertake no obligation to publicly update any forward-looking statements, whether as a result of new information, future events or otherwise, except as required by law.

You should read this prospectus and the documents that we reference in this prospectus and have filed as exhibits to the registration statement, of which this prospectus is a part, completely and with the understanding that our actual future results may be materially different from what we expect. We qualify all of our forward-looking statements by these cautionary statements.

This prospectus contains market data and industry forecasts that were obtained from industry publications. These data involve a number of assumptions and limitations, and you are cautioned not to give undue weight to such estimates. While we believe the market position, market opportunity and market size information included in this prospectus is generally reliable, such information is inherently imprecise.

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Currency exchange rates

The following table sets forth, for each period indicated, the low and high exchange rates for euros expressed in U.S. dollars, the exchange rate at the end of such period and the average of such exchange rates on the last day of each month during such period, based on the noon buying rate of the Federal Reserve Bank of New York for the euro. As used in this document, the term “noon buying rate” refers to the rate of exchange for the euro, expressed in U.S. dollars per euro, as certified by the Federal Reserve Bank of New York for customs purposes. The exchange rates set forth below demonstrate trends in exchange rates, but the actual exchange rates used throughout this prospectus may vary.

The following table sets forth, for each of the last six months, the low and high exchange rates for euros expressed in U.S. dollars and the exchange rate at the end of the month based on the noon buying rate as described above.

On June 12, 2015, the noon buying rate of the Federal Reserve Bank of New York for the euro was €1.00 = $1.1278. Unless otherwise indicated, currency translations in this prospectus reflect the June 12, 2015 exchange rate.

Information presented on a constant currency basis in this prospectus is calculated by translating current year results at prior year average exchange rates. Management reviews and analyzes business results excluding the effect of foreign currency translation because they believe this better represents our underlying business trends.

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Market information

Our ordinary shares have been trading on Euronext Brussels and Euronext Paris under the symbol “CYAD” since July 5, 2013.

The following table sets forth for the periods indicated the reported high and low closing sale prices per ordinary share on Euronext Brussels in euros, as well as the average trading volume for our ordinary shares for such periods.

On June 12, 2015, the last reported sale price of our ordinary shares on Euronext Brussels was €62.94 per share.

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Use of proceeds

We estimate that we will receive net proceeds from the global offering of approximately $89.5 (€79.4) million, assuming a public offering price of $70.98 (€62.94) per ADS in the U.S. offering and €62.94 per ordinary share in the European private placement, the closing price of our ordinary shares on Euronext Brussels on June 12, 2015, after deducting underwriting commissions and estimated offering expenses payable by us, and assuming no exercise of the underwriters’ option to purchase additional ordinary shares and ADSs. If the underwriters exercise in full their options to purchase additional ordinary shares and ADSs in the global offering , we estimate that we will receive net proceeds from the global offering of approximately $103.4 (€91.7) million, assuming a public offering price of $70.98 (€62.94) per ADS in the U.S. offering and €62.94 per ordinary share in the European private placement, the closing price of our ordinary shares on Euronext Brussels on June 12, 2015, after deducting underwriting commissions and estimated offering expenses payable by us.

A $1.00 (€0.89) increase (decrease) in the assumed public offering price of $70.98 (€62.94) per ADS in the U.S. offering and €62.94 per ordinary share in the European private placement, would increase (decrease) our net proceeds from the global offering by $1.3 (€1.2) million, assuming the number of the ordinary shares and the ADSs offered by us, as set forth on the cover page of this prospectus, remains the same and after deducting underwriting commissions. Each increase or decrease of 1,000,000 ADSs and ordinary shares in the number of ADSs and ordinary shares offered by us would increase or decrease the net proceeds to us from the sale of the ordinary shares and ADSs we are offering by $66.0 (€58.5) million, assuming that the assumed public offering price remains the same and after deducting underwriting commissions. Each increase of 1,000,000 ADSs and ordinary shares in the number of ADSs and ordinary shares offered by us together with a concomitant $1.00 (€0.89) increase in the assumed public offering price per ADS in the U.S. offering and €0.89 per ordinary share in the European private placement, would increase the net proceeds to us from the sale of ADSs and ordinary shares we are offering by $68.2 (€60.5) million, after deducting underwriting commissions. Each decrease of 1,000,000 shares in the number of ordinary shares and ADSs offered by us together with a concomitant $1.00 (€0.89) decrease in the assumed public offering price per ADS in the U.S. offering and €0.89 per ordinary share in the European private placement, would decrease the net proceeds to us from the sale of the ADSs and ordinary shares we are offering by $66.4 (€58.9) million, after deducting underwriting commissions. The actual net proceeds payable to us will adjust based on the actual number of ADSs and ordinary shares offered by us, the actual public offering price and other terms of the global offering determined at pricing.

The principal purposes of the global offering are to increase our financial flexibility, create a public market for our securities in the United States and facilitate our access to the public equity markets. We currently expect to use the net proceeds from the global offering as follows:

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Use of proceeds

We expect to use the remainder of any net proceeds from the global offering for working capital and other general corporate purposes.

We may also use a portion of the net proceeds to in-license, acquire or invest in complementary technologies, products or assets. However we have no current plan, commitments or obligations to do so.

Based on our current operation plans and assumptions, we believe that such proceeds, together with our existing cash, will be sufficient to fund our operations until at least the end of 2017. However, changing circumstances may cause us to increase our spending significantly faster than we currently anticipate, and we may need to spend more money than currently expected because of circumstances beyond our control. We may require additional capital for the further development and commercialization of our drug product candidates and may need to raise additional funds sooner if we choose to expand more rapidly than we presently anticipate. We cannot be certain that additional funding will be available on acceptable terms, or at all. We have no committed source of additional capital and if we are unable to raise additional capital in sufficient amounts or on terms acceptable to us, we may have to significantly delay, scale back or discontinue the development or commercialization of our drug product candidates or other research and development initiatives. Our licenses may also be terminated if we are unable to meet the payment obligations under the agreements. We could be required to seek collaborators for our drug product candidates at an earlier stage than otherwise would be desirable or on terms that are less favorable than might otherwise be available or relinquish or license on unfavorable terms our rights to our drug product candidates in markets where we otherwise would seek to pursue development or commercialization ourselves. Any these events could significantly harm our business, prospects, financial condition and results of operations and cause the price of our ADSs and our ordinary shares to decline.

We currently have no specific plans as to how the net proceeds from the global offering will be allocated beyond the uses specified above and therefore management will retain discretion to allocate the remainder of the net proceeds of the global offering among these uses.

This expected use of the net proceeds from the global offering represents our intentions based upon our current plans and business conditions. As of the date of this prospectus, we cannot predict with certainty all of the particular uses for the net proceeds to be received upon the completion of the global offering or the amounts that we will actually spend on the uses set forth above. The amounts and timing of our actual expenditures and the extent of clinical development may vary significantly depending on numerous factors, including the progress of our development efforts, the status of and results from pre-clinical studies and any ongoing clinical trials or clinical trials we may commence in the future, as well as any collaborations that we may enter into with third parties for our drug product candidates and any unforeseen cash needs. As a result, our management will retain broad discretion over the allocation of the net proceeds from the global offering.

Pending our use of the net proceeds from the global offering, we intend to invest the net proceeds in a variety of capital preservation investments, including short-term, investment-grade, interest-bearing instruments.

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Dividend policy

We have never declared or paid any cash dividends on our ordinary shares. We do not anticipate paying cash dividends on our equity securities in the foreseeable future and intend to retain all available funds and any future earnings for use in the operation and expansion of our business. All of the ordinary shares, including in the form of the ADSs, offered by this prospectus will have the same dividend rights as all of our other outstanding ordinary shares. In general, distributions of dividends proposed by our board of directors require the approval of our shareholders at a meeting of shareholders with a simple majority vote, although our board of directors may declare interim dividends without shareholder approval, subject to the terms and conditions of the Belgian Company Code. See ‘‘Description of share capital.’’

Pursuant to Belgian law, the calculation of amounts available for distribution to shareholders, as dividends or otherwise, must be determined on the basis of our non-consolidated statutory financial accounts prepared under Belgian GAAP, and not on the basis of IFRS consolidated accounts. In addition, under the Belgian Company Code, we may declare or pay dividends only if, following the declaration and issuance of the dividends, the amount of our net assets on the date of the closing of the last financial year according to our statutory annual accounts (i.e., the amount of the assets as shown in the balance sheet, decreased with provisions and liabilities, all as prepared in accordance with Belgian accounting rules), decreased with the non-amortized costs of incorporation and expansion and the non-amortized costs for research and development, does not fall below the amount of the paid-up capital (or, if higher, the called capital), increased with the amount of non-distributable reserves. Finally, prior to distributing dividends, we must allocate at least 5% of our annual net profits (under our non-consolidated statutory accounts prepared in accordance with Belgian accounting rules) to a legal reserve, until the reserve amounts to 10% of our share capital.

For information regarding the Belgian withholding tax applicable to dividends and related U.S. reimbursement procedures, see ‘‘Material income tax considerations—Belgian Tax Consequences.’’

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