RISK FACTORS

Investing in ADSs representing our ordinary shares involves a high degree of risk. You should carefully consider the following risk factors and all other information contained in this prospectus, including our Consolidated Financial Statements and the related notes, before investing in the ADSs. 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 the ADSs. If any of these risks materialize, our business, results of operations or financial condition could suffer, the price of the ADSs could decline and you could lose part or all of your investment. Additional risks and uncertainties not currently known to us or that we now deem immaterial may also harm us and adversely affect your investment in the ADSs.

Risks Related to Our Business

We are heavily dependent on sales of RUCONEST^® in the United States and Europe. If we are unable to continue to commercialize RUCONEST^®, our business could be materially harmed. In addition, our development pipeline remains dependent on the C1INH franchise in the near term.

Our company has, to date, been substantially focused on the development and commercialization of RUCONEST^®, and we expect to continue to be dependent primarily on revenues from RUCONEST^® sales in the near term. Any adverse events or findings regarding the properties, efficacy or safety of RUCONEST^®, or material constraints on the manufacturing of RUCONEST^®, may have a material impact on our financial results and operations.

Our ability to meet expectations with respect to sales of RUCONEST^®, generate revenues from such sales, and attain and maintain positive cash flow from operations, in the time periods anticipated, or at all, will depend on a number of factors, including, among others:

In addition, our near-term product candidate pipeline is dependent on development of rhC1INH for new formulations and new indications. If we encounter adverse market acceptance, regulatory, pricing, intellectual property or manufacturing issues, the development of rhC1INH for new formulations and new indications may be adversely impacted.

We face significant competition, which may result in others discovering, developing or commercializing products before or more successfully than we do.

The development and commercialization of pharmaceuticals is highly competitive. In particular, RUCONEST^® faces intense competition from other products used to treat Hereditary Angioedema, or HAE. Several products

11

have been approved in the U.S. and Europe for the treatment of HAE attacks, including human blood plasma derived C1INH products. Oral products for the prevention of HAE attacks are also being developed and the first one may be approved in late 2020. Consequently, we may not obtain sufficient market penetration with RUCONEST^® or a sufficient level of sales of the product to allow it to remain profitable. New technologies from competitors may make RUCONEST^®, one or more of our product candidates or our technology obsolete.

Our competitors include major international pharmaceutical companies as well as smaller or regional specialty pharmaceutical and biotechnology companies. Many of our competitors are larger and have greater financial resources and expertise in research and development, manufacturing, preclinical testing, conducting clinical trials, obtaining regulatory approvals, prosecuting intellectual property rights and marketing approved products than we do. Such competitors may be better equipped to withstand changes in economic and industry conditions. Smaller or early stage companies may also be significant competitors, particularly through collaborative arrangements with large, established companies. Key competitive factors affecting the commercial success of our products and any other products that we develop or acquire are likely to be safety, efficacy, tolerability profile, reliability, convenience of dosing, price and reimbursement. We may also face future competition from companies selling generic alternatives to our products in countries where we do not have patent coverage, Orphan Drug status or another form of data or marketing exclusivity or where patent coverage or data or marketing exclusivity has expired, is not enforced, or may, in the future, be challenged.

We have only recently established our direct sales and marketing organization in Europe. If we are unable to maintain and grow our sales and marketing capabilities, particularly outside of the United States, or enter into agreements with third parties to market and sell our products outside of the United States and Europe, our business will be adversely affected.

We reacquired commercial rights to distribute RUCONEST® in Europe from Swedish Orphan Biovitrium AB, or SOBI, as of January 2020. Accordingly, we have only recently established our direct sales and marketing organizations in Europe. There are risks involved with both establishing and maintaining our own sales and marketing capabilities. For example, recruiting and training a commercial organization is expensive and time consuming and could delay any product launch. If the commercial launch of a product candidate for which we recruit a sales force and establish marketing capabilities is delayed or does not occur for any reason, we would have prematurely or unnecessarily incurred these commercialization expenses. This may be costly and our investment would be lost if we cannot retain or reposition our sales and marketing personnel.

Factors that may inhibit our efforts to commercialize our product candidates on our own include:

We enter into arrangements with third parties to perform sales, marketing and distribution services outside the United States and Europe. In addition, we have granted the China Shanghai Institute of Pharmaceutical Industry an exclusive license to commercialize RUCONEST^® in China, and we are solely dependent on their efforts to commercialize RUCONEST^® in that territory. We may receive certain regulatory and manufacturing-associated milestones, and we are eligible to receive low to mid-single digit royalties from sales in China by CSIPI or other affiliates of Sinopharm. Dependence on distribution arrangements and marketing alliances to commercialize our products in certain jurisdictions subjects us to a number of risks. We don’t have full control over such third parties and any of them may fail to devote the necessary resources and attention to sell and market our products effectively. In addition, such third parties may experience compliance related issues and associated government investigations. If such third party arrangements are terminated or allowed to expire, the marketing and sales of a product in that jurisdiction may be interrupted, which could adversely affect our revenues. In addition, we may not be successful in entering into arrangements with third parties to sell and market our product candidates or may be unable to do so on terms that are favorable to us. Please see the risk factor entitled “—We are subject to U.S. and certain foreign export and import controls, sanctions, embargoes, anti-corruption laws, and anti-money laundering laws and regulations. Compliance with these legal standards could impair our ability to compete in domestic markets. We can face criminal liability and other serious consequences for violations, which can harm our business.”

12

We rely on named patient sales of RUCONEST^® in certain territories where it has not yet been approved; however, there are no assurances that named patient sales of our products will continue at current levels, or at all.

RUCONEST^® is currently available on a named patient basis in certain countries where it is not yet approved. Named patient basis means physician-requested treatment for patients in territories where marketing authorization has not yet been obtained. There is no assurance that named patient sales will continue to be authorized in any particular country. Even if they are authorized, we will likely not be permitted to promote, market or otherwise engage in proactive selling activities for products sold on a named patient basis, which makes named patient sales much less predictable, and susceptible to unexpected decreases. If violations of any laws or governmental regulations are found to have occurred in connection with our products significant criminal or civil lawsuits may be filed, or investigations may be commenced.

The commercial success of any current or future product candidate will depend upon the degree of market acceptance by physicians, patients, payors and others in the medical community.

The commercial success of our products and product candidates will depend in part on the medical community, patients, and payors accepting our product candidates as effective, safe and cost-effective. Notwithstanding the level of revenues historically generated from the sale of RUCONEST^®, if RUCONEST^® or our product candidates do not achieve an adequate level of acceptance, we may struggle to continue to generate significant product revenues and may not in the future generate any profits from operations. The degree of market acceptance of RUCONEST^®, or our product candidates, if approved for commercial sale, will depend on a number of factors, including:

Even if a product candidate displays a favorable efficacy and safety profile in preclinical studies and clinical trials, market acceptance of the product, if approved for commercial sale, will not be known until after it is launched. Our efforts to educate the medical community and payors on the benefits of our products and product candidates may require significant resources and may never be successful. Such efforts to educate the marketplace may require more resources than are required by the conventional technologies marketed by our competitors.

The successful commercialization of our product candidates will depend in part on the extent to which governmental authorities and health insurers establish adequate coverage, reimbursement levels and pricing policies. Failure to obtain or maintain coverage and adequate reimbursement for our product candidates, if approved, could limit our ability to market those products and decrease revenue generating ability.

The availability and adequacy of coverage and reimbursement by governmental healthcare programs such as Medicare and Medicaid, private health insurers and other third-party payers is essential for many patients to be able to afford prescription medications such as RUCONEST^® and potential product candidates, assuming regulatory approval is obtained. Our ability to achieve acceptable levels of coverage and reimbursement for products by governmental authorities, private health insurers and other organizations fundamentally impacts the potential success of RUCONEST^® and product candidates. Assuming we obtain coverage for our product

13

candidates by third-party payers, the resulting reimbursement payment rates may not be adequate or may require co-payments that patients find unacceptably high. We cannot be sure that coverage and reimbursement in the United States, the EU Member States, or elsewhere will be available for the product candidates or any product that we may develop, and any reimbursement that may become available may be decreased or eliminated in the future. There is an increasing tendency of health insurers to reduce healthcare costs by limiting both the coverage and the level of reimbursement for new therapeutic products and in some cases by refusing to provide coverage altogether.

Because coverage and reimbursement determinations are made on a payor-by-payor basis, obtaining coverage and adequate reimbursement from a third party payor does not guarantee that we will obtain similar coverage or reimbursement from another third party payor. Reimbursement may impact the demand for, or the price of, any product candidate for which we obtain marketing approval. If reimbursement is not available or is available only to limited levels, we may not be able to successfully commercialize any products for which we obtain marketing approval. Failure to secure or retain adequate coverage or reimbursement for our products by third-party payors, or delays in processing approvals by those payors, could result in the loss of sales, loss of customers, or reputational damage, which could have a material adverse effect on our business, financial condition and operating profit.

Further, it is possible that a third-party payer may consider our product candidates as substitutes and only offer to reimburse patients for a less expensive product. Even if we show improved efficacy or convenience of administration with our product candidates compared to products marketed by our competitors and the prevailing standard of care, the pricing of existing therapies may still limit the amount we could charge. Third-party payers may deny or revoke the reimbursement status of any given product or establish new prices for existing marketed products that inhibit us from realizing an appropriate return on our investment in the product candidates. If reimbursement is not available or is available only at limited levels, we may not be able to successfully commercialize our product candidates, and may not be able to obtain a satisfactory financial return on them.

Outside the United States, international operations are generally subject to extensive governmental price controls and other market regulations, and we believe the increasing emphasis on cost-containment initiatives in Europe, Canada, and other countries has and will continue to put pressure on the pricing and usage of our products. In many countries, the prices of medical products are subject to varying price control mechanisms as part of national health systems. Other countries allow companies to fix their own prices for medical products, but monitor and control company profits. Additional foreign price controls or other changes in pricing regulation could restrict the amount that we are able to charge for our product candidates. Accordingly, in markets outside the United States, the reimbursement for our products may be reduced compared with the United States and may be insufficient to generate commercially reasonable revenues and profits.

Many of our product candidates are at an early stage. We may spend several years developing current or future product candidates, and failure can occur at any stage.

Other than leniolisib, which is currently being studied in a phase 2/3 trial, both our rhC1INH projects and our non-rhC1INH product candidates are all at an earlier stage of development. Our next generation enzyme replacement therapy, or ERT for Pompe disease is in preclinical development.

We may spend several years developing current or future product candidates, and failure can occur at any stage. The product candidates to which we allocate our resources may not end up being successful. Because we have limited resources, we may forego or delay pursuit of opportunities with certain programs or product candidates or for indications that later prove to have greater commercial potential than our product candidates. Our spending on current and future research and development programs may not yield any commercially viable product candidates. If we do not accurately evaluate the commercial potential for a particular product candidate, we may relinquish valuable rights to that product candidate through strategic collaborations, licensing or other arrangements in cases in which it would have been more advantageous for us to retain sole development and commercialization rights to such product candidate. If any of these events occur, we may be forced to abandon our development efforts with respect to a particular product candidate or fail to develop a potentially successful product candidate. In addition, certain of our current or future product candidates may not demonstrate the pharmacological benefits we believe they may possess or compare favorably to existing, approved therapies.

Because our internal research capabilities are limited, we may be dependent upon pharmaceutical companies, biotechnology companies, academic scientists and other researchers to sell or license product candidates,

14

approved products or the underlying technology to us. The success of this strategy depends upon our ability to identify, select, discover and acquire on favorable terms promising product candidates and products.

The outbreak of COVID-19 may result in disruptions to our commercialization, clinical trials, manufacturing and other business operations, which could have a material adverse effect on our business, financial condition, operating profit, cash flows and prospects.

The recent outbreak of the Coronavirus Disease 2019, or COVID-19, which has been declared a global pandemic by the World Health Organization, has spread across the globe and is impacting worldwide economic activity. A public health epidemic, including COVID-19, poses the risk that we or our employees, contractors, suppliers, distributors and other partners, as well as physicians treating HAE patients, may be prevented from conducting business and patient care activities for an indefinite period of time, including due to shutdowns and quarantines that may be requested or mandated by governmental authorities. Beginning in March 2020, we transitioned our field-based sales, market access, and medical employees to remote work and suspended work-related travel and in-person customer interactions with healthcare professionals and customers. Our increased reliance on personnel working from home may negatively impact productivity or disrupt, delay or otherwise adversely impact our business. In addition, remote working could increase our cyber security risk. General protective measures put into place at various governmental levels, including quarantines, travel restrictions and business shutdowns, may also negatively affect our operations.

There is no guarantee that the virus may not be more dangerous than currently observed, or may affect more people, or may result in longer term measures restricting further the ability of employees to complete their assigned tasks properly and on time. Our animal carers and staff involved in the production of RUCONEST^® may be affected, which would adversely affect our ability to manufacture RUCONEST^®. In addition, our clinical trials or those of our collaborators and investigational sponsors, including our planned Phase 2b study of the effects of RUCONEST^® in patients undergoing PCI accompanied by contrast-enhanced examinations and our open label, single-arm, multi-stage, multi-center Phase 1/2 study in late-stage pre-eclampsia, have been subject to delays and it remains uncertain when these clinical trials will resume or the degree to which COVID-19 will impact.

The continued spread of COVID-19 and the measures taken by the governments of countries affected, particularly the United States and the Netherlands, could also disrupt the supply chain and the manufacture or shipment of RUCONEST^®. Any delays or interruptions in the manufacture and supply of RUCONEST^® could result in delays for our planned clinical trials, impair our ability to meet demand for new RUCONEST^® prescriptions and impede our clinical trial recruitment, testing, monitoring, data collection and analysis and other related activities.

Any of the foregoing factors could have a material adverse impact on our business, financial condition, operating profit, cash flows and prospects. The extent to which COVID-19 impacts our operations and those of our third-party partners will depend on future developments, which are highly uncertain and cannot be predicted with confidence, including the duration of the pandemic, additional or modified government actions, new information which emerges concerning the severity of COVID-19 and the actions taken to contain the virus or treat its impact, among others. In particular, the speed of the continued spread of COVID-19 globally, and the magnitude of interventions to contain the spread of the virus, will determine the impact of the pandemic on our operations.

Any future acquisitions we make may expose us to risks that could adversely affect our business, and we may not achieve the anticipated benefits of acquisitions of businesses or technologies.

As a part of our growth strategy, we may make additional acquisitions of complementary businesses. Any future acquisition will involve numerous risks and operational, financial and managerial challenges, including the following, any of which could adversely affect our business, financial condition or results of operations:

15

There can be no assurance that any of the acquisitions we may make will be successful or will be, or will remain, profitable. Our failure to successfully address the foregoing risks may prevent us from achieving the anticipated benefits from any acquisition in a reasonable time frame, or at all.

Negative public opinion and increased regulatory scrutiny of transgenic manufacturing techniques, or activism regarding the ethical treatment of our livestock, may damage public perception of RUCONEST^® and our product candidates, which may adversely affect sales of our products and our ability to obtain marketing approvals for our product candidates.

Public perception may be influenced by negative public statements regarding our transgenic manufacturing technology. Our transgenic manufacturing technology platform involves the genetic engineering of animals for the production of recombinant proteins. Genetic modification of food and livestock are a common subject of debate and negative publicity. In addition, animal rights activists commonly engage in campaigns to reduce or eliminate the use of animals in the commercialization of pharmaceutical products.

Negative publicity regarding genetic modification in general, and our transgenic manufacturing techniques in particular, or activism regarding the treatment of our livestock could result in reduced market acceptance for our products, increased governmental regulation, unfavorable public perception, potential regulatory delays in the testing or approval of our potential product candidates, stricter labeling requirements for those product candidates that are approved and a decrease in demand for any such product candidates. If any such adverse events occur, commercialization RUCONEST^® or further advancement of our clinical trials could be halted or delayed, which would have a material adverse effect on our business and operations.

16

We rely on third parties for the conduct of significant aspects of our preclinical studies and clinical trials and intend to rely on third parties in the future. If these third parties do not successfully carry out their contractual duties, our business may be adversely impacted.

We rely on third parties for the conduct of significant aspects of our preclinical studies and clinical trials. These third parties include Contract Research Organizations, or CROs, medical institutions, clinical investigators and contract laboratories. Although we design the clinical trials for our product candidates, we depend on these third parties for aspects of performing the trials. Our reliance on these third parties for research and development activities will reduce our control over these activities but will not relieve us of our regulatory or contractual responsibilities. For example, we will remain responsible for ensuring that each of our clinical trials is conducted in accordance with the general investigational plan and protocols for the trial.

The third parties we rely upon may fail to successfully carry out their contractual duties or meet expected deadlines, which may cause delays in the conduct of our preclinical and clinical studies.

If the CROs do not perform preclinical studies and clinical trials in a satisfactory manner, breach their obligations to us or fail to comply with regulatory requirements and other compliance obligations, the development, regulatory approval and commercialization of our product candidates may be delayed, we may not be able to obtain regulatory approval and commercialize our product candidates, or our development programs may be materially and irreversibly harmed. If we are unable to rely on preclinical and clinical data collected by our CROs, we could be required to repeat, extend the duration of, or increase the size of any clinical trials we conduct and this could significantly delay commercialization and require significantly greater expenditures. Please see the risk factor entitled “—We are subject to U.S. and certain foreign export and import controls, sanctions, embargoes, anti-corruption laws, and anti-money laundering laws and regulations. Compliance with these legal standards could impair our ability to compete in domestic markets. We can face criminal liability and other serious consequences for violations, which can harm our business.”

We are currently conducting clinical trials for certain of our product candidates at sites outside the United States. The FDA may not accept data from trials conducted in such locations.

We and the investigators conducting clinical trials for certain of our product candidates are studying our product candidates outside the United States. For example, the clinical trials of rhC1INH for the treatment of COVID-19, Acute Kidney Injury, or AKI and pre-eclampsia are being conducted outside the United States. Although the U.S. Food and Drug Administration, or FDA, may accept data from clinical trials conducted outside the United States, acceptance of these data is subject to conditions imposed by the FDA. For example, the clinical trial must be well designed and conducted and performed by qualified investigators in accordance with ethical principles. The trial population must also adequately represent the U.S. population, and the data must be applicable to the U.S. population and U.S. medical practice in ways that the FDA deems clinically meaningful.

In addition, while these clinical trials are subject to the applicable local laws, FDA acceptance of the data will depend on its determination that the trials also complied with all applicable U.S. laws and regulations. If the FDA does not accept the data from any trial that we conduct outside the United States, it would likely result in the need for additional trials, which would be costly and time-consuming and would delay or permanently halt our development of the applicable product candidates. In addition, in order to commence a clinical trial in the United States, we are required to seek FDA acceptance of an Investigational New Drug, or IND, for each of our product candidates. We cannot be sure any IND we submit to the FDA, or any similar CTA we submit in other countries, will be accepted. We may also be required to conduct additional preclinical testing prior to submitting an IND for any of our product candidates, and the results of any such testing may not be positive. Consequently, we may be unable to successfully and efficiently execute and complete necessary clinical trials in a way that leads to a New Drug Application, or NDA, or Biologics License Application, or BLA submission and approval of our product candidates. We may require more time and incur greater costs than our competitors and may not succeed in obtaining regulatory approvals of product candidates that we develop. Failure to commence or complete, or delays in, our planned clinical trials, could prevent us from or delay us in commercializing our product candidates.

17

We may not be able to obtain or maintain orphan drug exclusivity for our products or product candidates. If our competitors are able to obtain orphan drug exclusivity for their products, we may not be able to have competing products approved by the applicable regulatory authority for a significant period of time.

Regulatory authorities in some jurisdictions, including the United States, the European Union and the United Kingdom, may designate drugs for relatively small patient populations as orphan drugs. We obtained orphan drug designations from the FDA for the treatment of acute HAE attacks. Leniolisib has also received this designation from the FDA and the EMA. Generally, if a product 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 market exclusivity, which, subject to certain exceptions, precludes the EMA from approving another marketing application for a similar medicinal product or the FDA from approving another marketing application for the same drug for the same indication for that time period. The FDA defines “same drug” as a drug or biologic that contains the same active moiety and is intended for the same use. The applicable market exclusivity period for orphan drugs is ten years in the European Union and the United Kingdom and seven years in the United States. The European Union and United Kingdom exclusivity period can be reduced to six years if a drug no longer meets the criteria for orphan drug designation, including if the drug is sufficiently profitable so that market exclusivity is no longer justified.

In the European Union and the United Kingdom, a “similar medicinal product” is a medicinal product containing a similar active substance or substances as contained in a currently authorized orphan medicinal product, and which is intended for the same therapeutic indication. Obtaining orphan drug exclusivity for our product candidates is important to the product candidate’s success. If a competitor obtains orphan drug exclusivity for and approval of a product with the same indications as our product candidates as before we do and if the competitor’s product is the same drug or a similar medicinal product as ours, we could be excluded from the market for a certain period of time.

Even if we obtain orphan drug exclusivity for other product candidates in these indications, we may not be able to maintain it. For example, if a competitive product that is the same drug or a similar medicinal product as our product or product candidate is shown to be clinically superior to our product or product candidate, as applicable, any orphan drug exclusivity we have obtained will not block the approval of such competitive product. In addition, orphan drug exclusivity will not prevent the approval of a product that is the same drug as our product or product candidate if the FDA finds that we cannot assure the availability of sufficient quantities of the drug to meet the needs of the persons with the disease or condition for which the drug was designated.

The FDA Reauthorization Act, signed into law in August 2017, authorizes the FDA to impose additional clinical trial requirements on manufacturers seeking orphan drug designation and/or pediatric indications.

The results from our clinical trials may not be sufficiently robust to support the submission of marketing approval for our product candidates. Before we submit our product candidates for marketing approval, the FDA and/or the EMA may require us to conduct additional clinical trials or evaluate patients for an additional follow-up period.

The results from our clinical trials may not be sufficiently robust to support the submission of marketing approval for our product candidates. The FDA normally requires two registrational trials to approve a drug or biologic product, and thus the FDA may require that we conduct additional clinical trials of our product candidates prior to a BLA or NDA submission. The FDA typically does not consider a single clinical trial to be adequate to serve as a registrational trial unless it is, among other things, well-controlled and demonstrates a clinically meaningful effect on mortality, irreversible morbidity, or prevention of a disease with potentially serious outcome, and a confirmatory study would be practically or ethically impossible. Additionally, while the FDA recognizes the potential for natural history models to augment the need for placebo arms in trials for drugs that target very rare disease, where trial recruitment can be especially challenging, the FDA has found the use of natural history data as a historical comparator to be unsuitable for adequate and well-controlled trials in many circumstances. The FDA generally finds trials using historical controls to be credible only when the observed effect is large in comparison to variability in disease course.

Due to the nature of the indications our product candidates are designed to treat, and the limited number of patients with these conditions, a placebo-controlled and blinded study may not be practicable for ethical and other reasons. It is possible the FDA will not consider our comparisons to natural history data and, where

18

available, historical transplant data, to provide clinically meaningful results. Additionally, even though a product candidate may have achieved the primary endpoints in a registrational clinical trial, it is possible that the FDA or EMA may require us to conduct additional registrational trials, possibly involving a larger sample size or a different clinical trial design, especially if the FDA or EMA does not find the results from these trials to be sufficiently persuasive to support a BLA/NDA or Marketing Authorization Application, or MAA, submission, as applicable. The FDA or EMA may also require that we conduct a longer follow-up period of patients treated with our product candidates prior to accepting our BLA/NDA or MAA submission, as applicable.

In addition, data obtained from preclinical and clinical activities are subject to varying interpretations, which may delay, limit or prevent regulatory approval. There can be no assurance that the FDA, EMA or other foreign regulatory bodies will find the efficacy endpoints in our registrational trials or any efficacy endpoint we propose in future registrational trials to be sufficiently validated and clinically meaningful, or that our product candidates will achieve the pre-specified endpoints in current or future registrational trials to a degree of statistical significance, and with acceptable safety profiles. We also may experience regulatory delays or rejections as a result of many factors, including SAEs involving our product candidates, changes in regulatory policy or changes in requirements during the period of our product candidate development. Any such delays could materially and adversely affect our business, financial condition, results of operations and prospects.

We expect that the FDA and EMA will assess the totality of the safety and efficacy data from our product candidates in reviewing any future BLA or NDA, or MAA, submissions. Based on this assessment, the FDA or EMA may require that we conduct additional preclinical studies or clinical trials prior to submitting or approving a BLA or NDA, or MAA, for our target indications.

If the FDA or the EMA requires additional trials, we would incur increased costs and delays in the marketing approval process, which may require us to expend more resources than we have available. In addition, it is possible that the FDA and the EMA may have divergent opinions on the elements necessary for a successful BLA/NDA and MAA, respectively, which may cause us to alter our development, regulatory and/or commercialization strategies.

Our assumptions and estimates regarding prevalence and the addressable markets for our products and product candidates may be inaccurate, which could have a material adverse effect on our revenues and cash position.

If there are fewer actual patients than estimated, or if any product approval is based on narrower definitions of patient populations, our revenues and cash position could be materially and adversely affected. The patient population for the diseases that our products treat is very small, and networking, data gathering and support channels are not as established as those for more prevalent and researched disease indications. There is no patient registry or other method of establishing with precision the actual number of patients of our existing potential future indications in any geography. Estimating the prevalence of a rare disease is difficult and we therefore must rely on assumptions, beliefs and an amalgam of information from multiple sources, resulting in potential under or over-reporting. There is no guarantee that our assumptions and beliefs are correct, or that the methodologies used and data collected have generated or will continue to generate accurate estimates. There is therefore uncertainty around the estimated total potential addressable patient population for treatment with RUCONEST^® worldwide. In addition, the potential market opportunity for our product candidates that we may develop is difficult to estimate precisely, particularly given that the orphan drug markets which are targeted are, by their nature, relatively unknown. Our estimates of the potential market opportunity for each of these product candidates are predicated on several key assumptions, such as industry knowledge and publications, third-party research reports and other surveys. If any of our assumptions prove to be inaccurate, then the actual market for RUCONEST^®, or our other or future product candidates, could be smaller than our estimates of the potential market opportunity. If that turns out to be the case, our product revenue may be limited, and we may be unable to achieve or maintain profitability, which could have a material adverse effect on our business, financial condition, results of operations and prospects.

We are dependent on a limited number of suppliers for some of our components and materials used in our product candidates and product.

We rely on a limited number of suppliers for certain essential materials incorporated into products and product candidates. Certain of our suppliers are based in Europe, while a significant percentage of RUCONEST^® sales

19

are conducted in the US. If international shipping is disrupted, we may not be able to supply sufficient quantities of RUCONEST^® for sale in the US. Any disruption in the supply of these materials could adversely affect our ability to deliver product or complete clinical trials. Other studies of product candidates, regulatory applications or commercializing product candidates in a timely and commercially valuable manner, may be adversely affected, should supply be disrupted.

We cannot be sure that these suppliers will remain in business (including those affected by COVID-19), 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. Our use of a limited number of suppliers of raw materials, components and finished goods exposes us to several risks, including disruptions in supply, price increases, late deliveries and an inability to meet customer demand. There are, in general, relatively few alternative sources of supply for these components. These vendors may be unable or unwilling to meet our future demands for our clinical trials or commercial sale. Establishing additional or replacement suppliers for these components could take a substantial amount of time and it may be difficult to establish replacement suppliers who meet regulatory requirements. Any disruption in supply from any supplier or manufacturing location could lead to supply delays or interruptions which would damage our business, financial condition, results of operations and prospects.

If we are required to switch to a replacement supplier, the manufacture and delivery of our product and product candidates could be interrupted for an extended period, adversely affecting our business. Establishing additional or replacement suppliers may not be accomplished quickly. If we are able to find a replacement supplier, the replacement supplier would need to be qualified and may require additional regulatory authority approval, which could result in further delay. For example, the FDA or EMA could require additional supplemental data, manufacturing data and comparability data if we rely upon a new supplier. While we seek to maintain adequate inventory of the components and materials used in our product candidates, any interruption or delay in the supply of components or materials, or our inability to obtain components or materials from alternate sources at acceptable prices in a timely manner, could impair our ability to conduct our clinical trials and, if our product candidates are approved, to meet the demand of our customers and cause them to cancel orders.

In addition, as part of the FDA’s approval of our product candidates, the FDA must review and approve the individual components of our production process, which includes raw materials, the manufacturing processes and facilities of our suppliers. Our reliance on these suppliers subjects us to a number of risks that could harm our reputation, business, and financial condition, including, among other things:

If any of these risks materialize, costs could significantly increase and our ability to conduct our clinical trials and, if our product candidates are approved, to meet demand for our products could be impacted.

20

Any contamination in the manufacturing process for our recombinant products, shortages of raw materials or failure of any of our key suppliers to deliver necessary components could result in delays in our clinical development or marketing schedules.

We use living mammals as the source for our recombinant products. Our transgenic manufacturing platform bears the risk of failure due to contamination of the produced milk, diseases of the producing livestock or a breakdown of the facilities. Any contamination could adversely affect our ability to produce, release or administer our recombinant products on schedule and could, therefore, harm our results of operations and cause reputational damage. Additionally, although our recombinant products are tested for contamination prior to release, if a contaminated product was administered to a patient, it could result in harm to the patient. A material shortage, contamination, recall or restriction on the raw materials we use in the manufacture of our recombinant products could adversely impact or disrupt the commercial manufacturing or the production of clinical material, which could adversely affect our development timelines and our business, financial condition, results of operations and prospects.

We depend on third-party manufacturers for the production of rhC1INH for commercial supply and clinical trials of RUCONEST^®, as well as our other product candidates for clinical trials. Interruption in supply could materially and adversely affect sales.

We have entered into (downstream) manufacturing and supply agreements for RUCONEST^® with, among others, Sanofi and BioConnection. We are also preparing to develop additional downstream manufacturing capabilities of our own. It is uncertain whether and to what extent we will be able to develop such capabilities or enter into such partnerships or agreements on a timely basis and on acceptable terms. A failure to develop or sufficiently contract additional manufacturing capacity on a timely basis could have significant adverse effect on our business.

The release of product to the market is dependent on a set of quality control procedures. Some of these procedures, although validated, are very sensitive and complex. We do not have a Good Manufacturing Practice, or GMP, certified analytical lab capable of performing the quality control procedures needed for the release of product, and we rely on third parties for this task.

We do not have experience as a company managing a manufacturing facility.

We are currently planning the construction of a downstream manufacturing facility for RUCONEST^®. Operating our own manufacturing facility requires significant resources, and we do not have experience as a company in managing a manufacturing facility. In part because of this lack of experience, we cannot be certain that our manufacturing plans will be completed on time, if at all.

In addition, if we switch from our current Contract Manufacturing Organizations, or CMOs to our own manufacturing facility for one or more of our product candidates in the future, we may need to conduct additional analytical or clinical trials to bridge our modified product candidates to earlier versions. Failure to successfully operate our planned manufacturing facility could adversely affect the commercial viability of our product candidates.

Our future success depends on our ability to hire and retain key executives and to attract, retain and motivate qualified personnel.

Our future success depends on our ability to attract and retain key management personnel, scientific and technical personnel, particularly in the biopharmaceutical industry. Our ability to continue our operations and implement our strategy depends upon retaining, recruiting and motivating employees, especially with respect to our management team and research personnel. Experienced employees in the biopharmaceutical and biotechnology industries are in high demand and competition for their talents can be intense, especially in the Netherlands, where we maintain our principal operations. We have entered into employment agreements with executive officers and other key employees, but any employee may terminate his or her employment at any time or may be unable to continue in his or her role. The loss of any executive or key employee, or an inability to recruit desirable candidates or find adequate third parties to perform such services on reasonable terms and on a timely basis, could have a material adverse effect on our business, financial condition, results of operations and prospects. If we are not able to attract, retain and motivate necessary personnel to accomplish our business

21

objectives, we may experience constraints that could significantly impede our ability to achieve our development and commercial objectives, our ability to raise additional capital and our ability to implement our business strategy.

Our business, products or product pricing could be subject to negative publicity, which could have a material adverse effect on our reputation, business, financial position, results of operations, liquidity and cash flows.

In recent years, the pharmaceutical industry has been the subject of public complaints and significant publicity regarding the pricing of pharmaceutical products, including publicity and pressure resulting from prices charged by competitors and peer companies for new products as well as price increases by competitors and peer companies on older products that the public has deemed excessive. We may experience downward pricing pressure on the price of RUCONEST^® and any other future approved products due to social or political pressure to lower the cost of drugs, which could reduce our revenue and future profitability. Orphan drugs in particular have received recent negative publicity for the perceived high prices charged for them by their manufacturers, and as a result orphan drug developers such as us may be negatively impacted by such publicity and any U.S. or other government regulatory response. Due to these factors, we may suffer public criticism and negative publicity in media coverage, by industry trade associations and legislators.

Any of the events or developments described above could result in reputational harm and reduced market acceptance and demand for our products, could harm our ability to market our products in the future, could cause us to incur significant expense, could cause our senior management to be distracted from execution of our business strategy, and could have a material adverse effect on our business, reputation, financial condition, results of operations, liquidity, cash flows and/or share price.

We depend on our information technology systems, and any failure of these systems could harm our business. Any real or perceived security breaches, loss of data, and other disruptions or incidents could compromise the privacy, security, integrity or confidentiality of sensitive information related to our business or prevent us from accessing critical information and expose us to liability and reputational harm, which could adversely affect our business, results of operations and financial condition.

We collect and maintain data and information that is necessary to conduct our business, and we are increasingly dependent on information technology systems and infrastructure to operate our business, including systems infrastructure operated and maintained by our third-party suppliers or providers. In the ordinary course of our business, we collect, store and transmit large amounts of confidential information, including intellectual property, proprietary business information and personal information. It is critical that we do so in a secure manner to maintain the privacy, security, confidentiality and integrity of such confidential information. We have established physical, electronic and organizational measures to safeguard and secure our systems and facilities to prevent an information compromise, and rely on commercially available systems, software, tools and monitoring to provide security for our information technology systems and the processing, transmission and storage of digital information. We have also outsourced elements of our information technology infrastructure, and as a result, a number of third-party vendors may or could have access to our confidential information. Our internal information technology systems and infrastructure, and those of our current and any future collaborators, contractors and consultants and other third parties on which we rely, are vulnerable to damage or unauthorized access or use resulting from computer viruses, malware, natural disasters, terrorism, war, telecommunication and electrical failures, denial-of-service attacks, cyber-attacks or cyber-intrusions over the Internet, hacking, phishing and other social engineering attacks, attachments to emails, persons inside our organization (including employees or contractors), lost or stolen devices, or persons with access to systems inside our organization.

The risk of a security breach or disruption or data loss, particularly through social engineering attacks, cyber-attacks or cyber intrusion, including by computer hackers, foreign governments and cyber terrorists, has generally increased as the number, intensity and sophistication of attempted attacks and intrusions from around the world have increased. In addition, the prevalent use of mobile devices that access confidential information increases the risk of data security breaches, which could lead to the loss of confidential information or other intellectual property. The costs to us to mitigate, investigate and respond to potential security incidents, breaches, disruptions, network security problems, bugs, viruses, worms, malicious software programs and security vulnerabilities could be significant, and while we have implemented security measures to protect our data security and information technology systems, our efforts to address these problems may not be successful, and these problems could result in unexpected interruptions, delays, cessation of service and other harm to our

22

business and our competitive position. If such an event were to occur and cause interruptions in our operations, it could result in a material disruption of our product development programs. For example, the loss of clinical trial data from completed or ongoing or planned clinical trials could result in delays in our regulatory approval efforts and significantly increase our costs to recover or reproduce the data. Moreover, if a real or perceived security breach affects our systems (or those of our third party providers or suppliers) or results in the loss of or accidental, unlawful or unauthorized access to, use of, release of or other processing of personally identifiable information or clinical trial data, our reputation could be materially damaged. In addition, such a breach may require notification to governmental agencies, the media or individuals pursuant to various supranational, national, federal or state privacy and security laws in the European Union or the U.S., if applicable, including the General Data Protection Regulation, or GDPR, the Health Insurance Portability and Accountability Act of 1996, or HIPAA, as amended by the Health Information Technology for Clinical Health Act of 2009, or HITECH and its implementing rules and regulations, as well as regulations promulgated by the Federal Trade Commission and state breach notification laws. We would also be exposed to a risk of loss, negative publicity, harm to our reputation, governmental investigation and/or enforcement actions, claims or litigation and potential liability, which could materially adversely affect our business, results of operations and financial condition. The global data protection landscape is rapidly evolving, and we may be affected by or subject to new, amended or existing laws and regulations in the future, including as our operations continue to expand or if we begin to operate in foreign jurisdictions. Please see the risk factor entitled “—If we fail to comply with UK, EU or U.S. privacy and data security laws and regulations, we may be subject to civil and criminal penalties and other liability.”

Risks Related to Intellectual Property

Our success is dependent on our ability to obtain and protect rights to proprietary technology and to develop our technology and products without infringing the proprietary rights of third parties.

We rely, and will continue to rely, on a combination of patents, trademarks and confidentiality agreements with employees, consultants, collaborators, advisors and other third parties to protect the intellectual property related to our current and future product candidates. We use patents and licensing to protect our products and technology. We are also careful to develop products that don’t infringe on the proprietary rights of third parties. Currently, we have several patent applications granted and pending in countries including the US, Europe and Japan. The patent positions of pharmaceutical companies can be uncertain and may involve complex legal and factual questions.

The patents that we own now or the patents and patent applications that we may own or in-license in the future may not have patentable claims that protect our current and future product candidates in the relevant jurisdictions where we intend to commercialize such products. There is no assurance that we are aware of all potentially relevant prior art relating to future patent applications. As such, the patent examiner may find prior art that can prevent a patent from issuing from a pending patent application. During the patent examination process, we may be required to narrow the pending claims to overcome prior art, a process that may limit the scope of patent protection. Even if patents do successfully issue based on our future patent applications, and even if the issued patents cover our current and future product candidates, including their compositions formulation, method of manufacture, and method of use, third parties may challenge our issued patents’ validity, enforceability or scope, which may result in such patents being narrowed, invalidated or held unenforceable. Any successful opposition to these patents or any other patents owned by or licensed to us in the future could deprive us of rights necessary for the successful commercialization of any of our current or future product candidates, if approved. Further, if we encounter delays in regulatory approvals, the period of time during which we could market a product candidate under patent protection could be reduced.

If the patent applications we may own or in-license in the future with respect to our current and future product candidates fail to issue, if their breadth or strength of protection is threatened, or if they fail to provide meaningful exclusivity for any of our current or future product candidates, it could dissuade other companies from collaborating with us to develop future product candidates, and threaten our ability to commercialize our current and future product candidates. Notably, pending patent applications cannot be enforced against third parties practicing the technology claimed in such applications unless and until a patent issues from such applications. Any such outcome could have an adverse effect on our business.

Moreover, our technologies and products may infringe on third party intellectual property rights. As a result, we may face litigation or other legal proceedings concerning its intellectual property. These processes can be time-

23

consuming and costly. In the event of an unfavorable ruling in patent or intellectual property litigation, we could be subject to significant liabilities to third parties, or be required to cease developing, manufacturing or selling the affected products or technology. Each of these outcomes may adversely affect our financial position. We may also be confronted with claims which are raised with the main aim of exploiting the nuisance value of publicly raised claims. For example, a competitor alleged that we were infringing their intellectual property as a result of the hiring of an employee. Although this dispute was resolved in our favor, we cannot guarantee that similar claims will not be made against us in the future. In order to prevent the infringement of third-party intellectual property rights, we may need to acquire licenses for patents held by third parties to re-establish or maintain its freedom to operate, possibly on unfavorable terms. A failure to obtain licenses for patents held by third parties, or failure to obtain them on favorable terms, may have a material adverse effect on our financial and operational position.

The patent position of biotechnology and pharmaceutical companies generally is highly uncertain, involves complex legal and factual questions, and has in recent years been the subject of much litigation. In addition, the laws of foreign countries may not protect our rights to the same extent as the laws of the United States. For example, European patent law restricts the patentability of methods of treatment of the human body more than U.S. law does. Publications of discoveries in scientific literature often lag behind the actual discoveries, and patent applications in the United States and other jurisdictions are typically not published until 18 months after filing, or in some cases not at all. Therefore, we cannot know with certainty whether we were the first to make the inventions claimed in our owned or licensed patents or pending patent applications, or that we were the first to file for patent protection of such inventions. As a result, the issuance, scope, validity, enforceability and commercial value of our patent rights are highly uncertain. Our future patent applications may not result in patents being issued which protect our technology or products, in whole or in part, or which effectively prevent others from commercializing competitive technologies and products. Changes in either the patent laws or interpretation of the patent laws in the United States and other countries may diminish the value of our patents or narrow the scope of our patent protection.

Patent reform legislation could increase the uncertainties and costs surrounding the prosecution of our patent applications and the enforcement or defense of our issued patents. On September 16, 2011, the Leahy-Smith America Invents Act, or the Leahy-Smith Act, was signed into law. The Leahy-Smith Act made a number of significant changes to United States patent laws. These include provisions that affect the way patent applications are prosecuted and challenged at the U.S. Patent and Trademark Office, or USPTO, and may also affect patent litigation. The USPTO has developed and continues to develop new regulations and procedures to govern administration of the Leahy-Smith Act, and many of the substantive changes to patent law associated with the Leahy-Smith Act, and in particular, the first to file provisions, became effective on March 16, 2013. Accordingly, it remains unclear what impact the Leahy-Smith Act, subsequent rulemaking, and judicial interpretation of the Leahy-Smith Act and regulations will have on the operation of our business. However, the Leahy- Smith Act and its implementation could increase the uncertainties and costs surrounding the prosecution of our patent applications and the enforcement or defense of our issued patents, all of which could have an adverse effect on our business and financial condition.

Moreover, future changes to the patent laws of the United States and foreign jurisdictions may adversely affect the term, scope, validity and enforceability of our or our licensor’s patent rights. For example, a 2019 bill (Terminating the Extension of Rights Misappropriated Act, or TERM Act, H.R. 3199) in the United States Congress aimed to reduce the term of certain drug patents in order to ease generic entry and increase competition. Changing political priorities could potentially drive more such initiatives. The inventorship and ownership rights for patents that we in-license or may own or in-license in the future may be challenged by third parties. Such challenges could result in loss of exclusive rights to such patents, which could limit our ability to stop others from using or commercializing similar or identical technology and products, or require us to obtain a license from such third parties on commercially reasonable terms to secure exclusive rights. If any such challenges to inventorship or ownership were asserted, there is no assurance that a court would find in our favor or that, if we choose to seek a license, such license would be available to us on acceptable terms or at all. Moreover, we may be subject to a third-party pre-issuance submission of prior art to the USPTO or become involved in pre- and post-issuance opposition, derivation, re-examination, inter partes review (“IPR”), post-grant review or interference proceedings challenging our patent rights or the patent rights of others. An adverse determination in any such submission, proceeding or litigation could reduce the scope of, or invalidate, our patent rights, allow third parties to commercialize our technology or products and compete directly with us,

24

without payment to us, or result in our inability to manufacture or commercialize products without infringing third-party patent rights.

In addition, if the breadth or strength of protection provided by our patents and patent applications, whether owned or in-licensed now or in the future, is threatened, it could dissuade companies from collaborating with us to license, develop or commercialize current or future product candidates.

The issuance of a patent is not conclusive as to its inventorship, scope, validity or enforceability, and our licensed patents may be challenged in the courts or patent offices in the United States. Such challenges may result in loss of exclusivity or freedom to operate or in patent claims being narrowed, invalidated or held unenforceable, in whole or in part, which could limit our ability to stop others from using or commercializing similar or identical technology and products, or limit the duration of the patent protection of our technology and products. Moreover, patents have a limited lifespan. In the United States, the natural expiration of a patent is generally 20 years after the filing of the earliest non-provisional application to which the patent claims priority. Various extensions may be available; however, the life of a patent, and the protection it affords, is limited. We may be required to disclaim a portion of patent term in order to overcome double patenting rejections from the patent office, thus potentially shortening our exclusivity period. Without patent protection for our current or future product candidates, we may be open to competition from generic versions of such products. Given the amount of time required for the development, testing and regulatory review of new product candidates, patents protecting such candidates might expire before or shortly after such candidates are commercialized. As a result, our licensed patent portfolio may not provide us with sufficient rights to exclude others from commercializing products similar or identical to ours.

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

Competitors may infringe or otherwise violate our patents, the patents of our licensor or our other intellectual property rights. To counter infringement or unauthorized use, we may be required to file legal claims, which can be expensive and time-consuming. In addition, in an infringement proceeding, a court may decide that an asserted patent is not valid or is unenforceable, or may refuse to stop the other party from using the technology at issue on the grounds that the asserted patent does not cover the technology in question. An adverse result in any litigation or defense proceedings could put one or more of asserted patents at risk of being invalidated or interpreted narrowly and could put a related patent application at risk of not issuing. The initiation of a claim against a third party may also cause the third party to bring counter claims against us such as claims asserting that our patents are invalid or unenforceable. In patent litigation in the United States, defendant counterclaims alleging invalidity or unenforceability are commonplace. Grounds for a validity challenge could be an alleged failure to meet any of several statutory requirements, including lack of novelty, obviousness, non-enablement or lack of statutory subject matter. Grounds for an unenforceability assertion could be an allegation that someone connected with prosecution of the patent withheld relevant material information from the USPTO, or made a materially misleading statement, during prosecution. Third parties may also raise similar validity claims before the USPTO in post-grant proceedings such as ex parte re-examinations, inter partes review, or post-grant review, or oppositions or similar proceedings outside the United States, in parallel with litigation or even outside the context of litigation. The outcome following legal assertions of invalidity and unenforceability is unpredictable. We cannot be certain that there is no invalidating prior art, of which we and the patent examiner were unaware during prosecution. For the patents and patent applications that we may license in the future, we may have limited or no right to participate in the defense of any licensed patents against challenge by a third party. If a defendant were to prevail on a legal assertion of invalidity or unenforceability, we would lose at least part, and perhaps all, of any future patent protection on our current or future product candidates. Such a loss of patent protection could harm our business.

We may not be able to detect or prevent, alone or with our licensors, misappropriation of our intellectual property rights, particularly in countries where the laws may not protect those rights as fully as in the United States. Our business could be harmed if in litigation the prevailing party does not offer us a license on commercially reasonable terms. Any litigation or other proceedings to enforce our intellectual property rights may fail, and even if successful, may result in substantial costs and distract our management and other employees.

Even if we establish infringement, the court may decide not to grant an injunction against further infringing activity and instead award only monetary damages, which may or may not be an adequate remedy. Furthermore,

25

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

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

The United States has recently enacted and implemented wide-ranging patent reform legislation. The U.S. Supreme Court and the U.S. Court of Appeals for the Federal Circuit have issued numerous precedential opinions in recent years narrowing the scope of patent protection available in certain circumstances or weakening 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 actions 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 patents that we have licensed or that we might obtain in the future. Similarly, changes in patent law and regulations in other countries or jurisdictions or changes in the governmental bodies that enforce them or changes in how the relevant governmental authority enforces patent laws or regulations may weaken our ability to obtain new patents or to enforce patents that we have licensed or that we may obtain in the future. The U.S. federal government retains certain rights in inventions produced with its financial assistance under the Bayh-Dole Act. The federal government retains a “nonexclusive, non-transferable, irrevocable, paid-up license” for its own benefit. The Bayh-Dole Act also provides federal agencies with “march-in rights.” March-in rights allow the government, in specified circumstances, to require the contractor or successors in title to the patent to grant a “nonexclusive, partially exclusive, or exclusive license” to a “responsible applicant or applicants.” If the patent owner refuses to do so, the government may grant the license itself.

We may infringe or be alleged to infringe the intellectual property rights of others, which may prevent or delay product development and commercialization efforts, requiring us to expend resources on litigation or other resolutions, which may materially and adversely affect our business.

Our success will depend in part on our ability to operate without infringing the intellectual property rights and other proprietary rights of third parties. Identification of third-party patent rights that may be relevant to our products and proprietary technology is difficult because patent searching is imperfect due to differences in terminology among patents, incomplete databases and the difficulty and uncertainty in assessing the meaning or scope of protection of patent claims. There could be issued patents of which we are or were not aware that our products infringe. There also could be patents that we believe we do not infringe, but that we may ultimately be found to infringe. Moreover, patent applications are in some cases maintained in secrecy until patents are issued. The publication of discoveries in the scientific or patent literature frequently occurs substantially later than the date on which the underlying discoveries were made and patent applications were filed. Because patents can take many years to issue, there may be currently pending applications of which we are unaware that may later result in issued patents that our products infringe. For example, pending applications may exist that provide support or can be amended to provide support for a claim that results in an issued patent that our product infringes.

Proceedings involving our patents or patent applications or those of others could:

We may not have the resources to adequately defend such claims, and even if successful in any such proceedings, we would incur substantial costs and divert management’s time and attention in pursuing these proceedings,

26

putting further strain on our resources, which could have a material adverse effect on our business, financial condition, results of operations and prospects. If we are unable to avoid infringing the patent rights of others, we may be required to seek a license, defend an infringement action or challenge the validity of the patents in court or other venue. Patent litigation is costly and time consuming. We may not have sufficient resources to bring these actions to a successful conclusion.

In addition, if we do not obtain a license, develop or obtain non-infringing technology, fail to defend an infringement action successfully or have infringed patents declared invalid, we may:

Our patents may be challenged, deemed unenforceable, invalidated or circumvented, and if we do not obtain or maintain patent protection for the products, our business may be materially harmed.

The patent positions of biotechnology and pharmaceutical companies involve complex legal and factual questions and, therefore, validity and enforceability cannot be predicted with certainty. U.S. patents and patent applications also may be subject to interference proceedings, ex parte re-examination, IPR and post-grant review proceedings, derivation proceedings and supplemental examination and may be challenged in district courts. Patents granted in certain other countries may be subjected to opposition or comparable proceedings lodged in various national and regional patent offices. These proceedings could result in either loss of the patent or denial of the patent application or loss or reduction in the scope of one or more of the claims of the patent or patent application. In addition, such interference, re-examination, opposition, post-grant review, IPR, derivation proceedings, supplemental examination or revocation proceedings may be costly. We will be able to protect our proprietary rights from unauthorized use by third parties only to the extent that our proprietary technologies are covered by valid and enforceable patents or are effectively maintained as trade secrets. The degree of future protection for our products and proprietary rights is uncertain, and it cannot be guaranteed that:

27

We enjoy only limited geographical protection with respect to certain patents.

Filing and prosecuting patent applications and defending patents covering product candidates in all countries throughout the world would be prohibitively expensive. Competitors may use our and our licensors’ technologies in jurisdictions where patent protection has not yet been obtained to develop their own products or may export infringing products to territories where enforcement rights are not as strong as in the United States or European Union. These products may compete with our product candidates, and our intellectual property rights may not be effective or sufficient to prevent such products from competing. Patent applications may be issued in some non-U.S. jurisdictions with different scope or they may be refused in certain jurisdictions, such as in China, which has different requirements for patentability.

Proceedings to enforce our patent rights in other jurisdictions, whether or not successful, could result in substantial costs and divert efforts and attention from other aspects of the business. They could also put our patents and patent applications at risk of being invalidated, denied or interpreted narrowly, and could provoke third parties to assert claims against us. We may not prevail in any lawsuits or damages or other remedies awarded to us, if any, and they may not be commercially meaningful. Accordingly, our intellectual property rights as enforced may be inadequate to obtain a significant commercial advantage and our efforts to protect our intellectual property rights may be unsuccessful or inadequate, which may adversely affect our ability to successfully commercialize our product candidates, which may have a material adverse effect on our business, financial condition, results of operations and prospects. Furthermore, while we intend to protect our intellectual property rights in our expected significant markets, we cannot ensure that we will be able to initiate or maintain similar efforts in all jurisdictions in which we may wish to market our product candidates. Accordingly, our efforts to protect our intellectual property rights in such countries may be inadequate, which may have an adverse effect on our ability to successfully commercialize our drug candidates in all of our expected, significant international markets.

Some countries also have compulsory licensing laws under which a patent owner may be compelled to grant licenses to third parties or laws limiting the enforceability of patents against government agencies or government contractors. In those countries, a patent owner may have limited recourse, which could materially diminish the value of such patents. If we or any of our licensors are forced to grant a license to third parties with respect to any patents relevant to our business, our competitive position may be adversely affected.

Risks Related to Government Regulation

The laws, regulations, ethical standards and international pharmaceutical codes in the areas of sales and marketing of pharmaceutical products, and interacting with healthcare professionals and patients, are very complex, and require a robust compliance program. Failure to comply with these laws and regulations could have a material adverse effect on our business, financial condition and results of operations.

The laws and regulations in the area of sales and marketing of pharmaceutical products, and in interacting with healthcare professionals and patients, are complex. We must comply with such laws in each jurisdiction in which we operate. These regulations are subject to change. We may not be able to meet such standards as they evolve and are implemented. In addition to changing regulatory requirements, our failure to comply with applicable regulatory requirements could result in, among other things, injunctions, product recalls, product seizures, declines in our share price, management distractions, reputational damage, loss of stakeholder trust, employee engagement, difficulties in recruitment, fines and criminal prosecution.

We must comply with a variety of laws and regulations, including regulatory, health and safety, license requirements, tax and Corporate Governance Regulations. We may be required to pay penalties for non-compliance with the laws and regulations of local, regional, national, US and EU authorities to which it is subject. A material change in the applicable laws and regulations, or in their interpretation or enforcement, could force us to alter our business strategy or operations, leading to additional costs or reductions of revenues, which may adversely affect its business.

28

We are subject to U.S. and certain foreign export and import controls, sanctions, embargoes, anti-corruption laws, and anti-money laundering laws and regulations. Non-compliance with these legal standards could impair our ability to compete in domestic markets. We can face criminal liability and other serious consequences for violations, which can harm our business.

We are subject to export control and import laws and regulations, including the U.S. Export Administration Regulations, U.S. Customs regulations, antitrust and competition laws, various economic and trade sanctions regulations administered by the U.S. Treasury Department’s Office of Foreign Assets Controls, the U.S. Foreign Corrupt Practices Act of 1977, as amended, or the FCPA, the United States domestic bribery statute contained in 18 U.S.C. § 201, the United States Travel Act, the USA PATRIOT Act, certain prohibitions under the Dutch Criminal Code (Wetboek van Strafrecht), under the Dutch Economic Offences Act (Wet op Economische Delicten), the U.K. Bribery Act and other state and national anti-bribery and anti-money laundering laws in the countries in which we conduct activities or countries that are otherwise relevant for our activities. Anti-corruption laws are interpreted broadly and prohibit companies and their employees, agents, contractors and other partners from authorizing, promising, offering, or providing, directly or indirectly, payments or anything else of value to recipients in the public or private sector (in relation to an act or omission (to be or having been) committed by the recipient). We may have direct or indirect interactions with officials and employees of government agencies or government-affiliated hospitals, universities, and other organizations. We can be held liable for the corrupt or other illegal activities of our employees, agents, contractors and other partners, even if we do not explicitly authorize or have actual knowledge of such activities, and we may participate in collaborations and relationships with third parties whose actions could potentially subject us to liability under the FCPA, the Bribery Act or local anti-corruption laws. We are also subject to other laws and regulations governing our international operations, including regulations administered by the governments of the United States and authorities in the European Union, including applicable export control regulations, economic sanctions and embargoes on certain countries and persons, anti-money laundering laws, import and customs requirements and currency exchange regulations, collectively referred to as the Trade Control laws.

Any violations of the laws and regulations described above may result in substantial civil and criminal fines and penalties, imprisonment, disgorgement, the loss of export or import privileges, debarment, tax reassessments, breach of contract and fraud litigation, reputational harm and other consequences.

If we fail to comply with UK, EU or U.S. privacy and data security laws and regulations, we may be subject to civil and criminal penalties and other liability.

We are also subject to laws and regulations covering data privacy and the protection of health-related and other personal information. The legislative and regulatory landscape for privacy and data protection continues to evolve, and there has been an increasing focus on privacy and data protection issues which may affect our business, including recently enacted laws in many jurisdictions where we operate. The collection and use of personal health data in the European Union is governed by the provisions of the General Data Protection Regulation (EU) 2016/679, or GDPR. This directive, which is wide-ranging in scope and includes extraterritoriality provisions that apply to certain entities located outside of the European Union, imposes several requirements relating to the consent of the individuals to whom the personal data relates, the information provided to the individuals, notification of data processing obligations to the competent national data protection authorities and the security and confidentiality of the personal data, and substantial fines for breaches of the data protection rules. The GDPR also imposes strict rules on the transfer of personal data out of the European Union to other countries (including the United States). Failure to comply with the requirements of the GDPR and the related national data protection laws of the EU Member States and the United Kingdom may result in large fines and other administrative penalties: a failure to comply could result in fines up to the greater of 4% of annual worldwide turnover for the preceding financial year or €20 million, with infringements being grouped into tiers which attract different maximum fine levels. Turnover in this context may include not only the entity in breach but also other group entities. Recent enforcement actions against multinational companies have resulted in significant fines. Following the United Kingdom’s formal departure from the European Union on January 31, 2020, the United Kingdom entered a transition period until December 31, 2020, during which time the GDPR will remain applicable to the United Kingdom, alongside the United Kingdom’s Data Protection Act 2018, or DPA 2018. At the end of the transition period, there is uncertainty regarding the future relationship between the United Kingdom and the European Union in relation to data protection. Once the United Kingdom leaves the European Union and the transition period has expired, the United Kingdom will become a “third country” for the purposes of data protection law. A “third country” is a country other than the EU Member States and the three

29

additional European Economic Area countries (Norway, Iceland and Liechtenstein) that have adopted a national law implementing the GDPR. Under the GDPR, personal data can only be transferred to third countries in compliance with specific conditions for cross-border data transfers. Appropriate safeguards are required to enable transfers of personal data from the European Union and EEA Member States. This status has a number of significant practical consequences, in particular for international data transfers, competent supervisory authorities and enforcement of the GDPR. In the United Kingdom, the DPA 2018 supplements the GDPR, and in particular sets out specific requirements related to the processing of “special categories of personal data,” including personal data related to health, genetic information and personal data related to criminal offenses or convictions. The DPA also creates a number of criminal offenses (punishable by uncapped fines) for organizations and in certain cases their directors and officers.

Under the GDPR regulations, we are considered a controller of data processing and area subject to several legal obligations. In particular, we are obligated to place importance on collection and processing of special categories of personal data which, for our purposes, is data that reveals genetic data or data concerning health. While we have taken steps to comply with the GDPR and the DPA 2018, we cannot assure you that our efforts to achieve and remain in compliance have been or will continue to be fully successful. The GDPR regulations and the DPA 2018 may impose additional responsibility and liability in relation to personal data that we process and we may be required to put in place additional mechanisms ensuring compliance with these or new data protection rules. This may be onerous and adversely affect our business, financial condition, results of operations and prospects.

In addition, we obtain patient health information from most healthcare providers that prescribe our products and research institutions with which we collaborate, and they are subject to privacy and security requirements under the Health Insurance Portability and Accountability Act of 1996, or HIPAA in the United States. Although we are not directly subject to HIPAA other than with respect to providing certain employee benefits, we could potentially be subject to criminal penalties if we knowingly obtain or disclose individually identifiable health information maintained by a HIPAA-covered entity in a manner that is not authorized or permitted by HIPAA. There are also state laws on patient health information, such as the California Confidentiality of Medical Information Act, which we are more directly subject to. As more states consider implementing such laws, we may face an ever-expanding patchwork of data privacy regulations.

Failure to comply with healthcare laws and laws and regulations covering data privacy and the protection of health-related and other personal information could result in government enforcement actions, which could include civil or criminal penalties, private litigation and adverse publicity and could negatively affect our business, financial condition, results of operations and prospects.

Our current and future relationships with healthcare professionals, customers and third-party payors are subject to applicable anti-kickback, fraud and abuse, privacy and security, transparency, and other healthcare laws and regulations, which could expose us to significant penalties, including criminal sanctions, civil penalties, contractual damages, reputational harm and diminished profits and future earnings.

We are subject to additional healthcare statutory and regulatory requirements and enforcement by the federal government and the states and foreign governments in the jurisdictions in which we conduct our business. Third-party payors will play a primary role in the recommendation and prescription of any product candidates for which we obtain marketing approval. Our current and future arrangements with third-party payors and customers 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 through which we research as well as market, sell and distribute any products for which we obtain marketing approval. Restrictions under applicable federal and state healthcare laws and regulations include the following:

30

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 it, we may be subject to significant civil, criminal and administrative penalties, damages, fines, disgorgement, imprisonment, exclusion from government funded healthcare programs, such as Medicare and Medicaid, integrity oversight and reporting obligations, contractual damages, reputational harm, diminished profits and future earnings, and the curtailment or restructuring of our operations, any of which could adversely affect our ability to operate our business and our results of operations. 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, they may be subject to significant criminal, civil or administrative sanctions, including exclusions from government funded healthcare programs.

31

If we fail to comply with our reporting and payment obligations under the Medicaid Drug Rebate Program or other governmental pricing programs that we participate in, we could be subject to additional reimbursement requirements, penalties, sanctions and fines, which could have a material adverse effect on our business, financial condition, results of operations and growth prospects.

We have certain price reporting obligations to the Medicaid Drug Rebate Program. Under the Medicaid Drug Rebate Program, we are required to pay a rebate to each state Medicaid program for RUCONEST^®, and expect to do so for any new approved products. Those rebates are based on pricing data we would have to report on a monthly and quarterly basis to the CMS the federal agency that administers the Medicaid Drug Rebate Program. These data include, among other things, the Average Manufacturing Price, or AMP, and the Best Price, or BP, which, in general, represents the lowest price available from the manufacturer to any entity in the U.S. in any pricing structure, calculated to include all sales and associated rebates, discounts and other price concessions. On June 17, 2020, CMS issued a proposed rule that, among other things, would change the methodology for calculating and reporting of AMP and BP in order to encourage manufacturers and states to enter into value-based purchasing arrangements. Although the public comment period has closed, we cannot provide any assurance that the proposed rule will be adopted or adopted in the form published. We are liable for errors associated with our submission of pricing data and for any overcharging of government payors. For example, failure to submit monthly/quarterly AMP and BP data on a timely basis could result in a civil monetary penalty for each day the submission is late beyond the due date. Failure to make necessary disclosures and/or to identify overpayments could result in allegations against us under the Federal False Claims Act and other laws and regulations. Any required refunds to the U.S. government or responding to a government investigation or enforcement action would be expensive and time consuming and could have a material adverse effect on our business, results of operations and financial condition.

Federal law requires that any company that participates in the Medicaid Drug Rebate Program also participate in the 340B program in order for federal funds to be available for the manufacturer’s drugs under Medicaid and Medicare Part B. The 340B program requires participating manufacturers to agree to charge statutorily defined covered entities no more than the 340B “ceiling price” for the manufacturer’s covered outpatient drugs. These 340B covered entities include a variety of community health clinics and other entities that receive health services grants from the Public Health Service, as well as hospitals that serve a disproportionate share of low-income patients. The ACA expanded the list of covered entities to include certain free-standing cancer hospitals, critical access hospitals, rural referral centers and sole community hospitals, but exempts “orphan drugs” from the ceiling price requirements for these covered entities. The 340B ceiling price is calculated using a statutory formula based on the AMP and rebate amount for the covered outpatient drug as calculated under the Medicaid Drug Rebate Program, and in general, products subject to Medicaid price reporting and rebate liability are also subject to the 340B ceiling price calculation and discount requirement. Any additional future changes to the definition of AMP and the Medicaid rebate amount under the ACA or other legislation or regulation could affect our 340B ceiling price calculations and negatively impact our results. In addition, legislation may be introduced that, if passed, would further expand the 340B program to additional covered entities or would require participating manufacturers to agree to provide 340B discounted pricing on drugs used in an inpatient setting.

RUCONEST^® has been approved by the FDA, the EMA and certain other regulatory authorities for the treatment of HAE attacks. Regulatory approval is limited to the specific indication for which approval has been granted and, unless we seek regulatory approval for additional indications, we will be prohibited from marketing RUCONEST^® for other indications. We may be subject to significant fines, penalties or injunctions if we are determined to have promoted or be promoting the use of RUCONEST^® for unapproved or “off-label” uses, resulting in damage to our reputation and business.

RUCONEST^® is approved by the FDA, the EMA and certain other regulatory authorities for the treatment of HAE attacks, but is not currently approved for the treatment of other indications. Regulatory authorities strictly regulate the promotional claims that may be made about prescription products, and RUCONEST^® may not be promoted for uses that are not approved, as reflected in its approved labeling. If we are not able to obtain regulatory approval for any desired future indications for our products and product candidates, our ability to effectively market and sell our products may be reduced and our business may be adversely affected.

While physicians may choose, in their independent medical judgment, to prescribe products for uses that are not described in the product’s labeling and for uses that differ from those tested in clinical trials and approved by the

32

regulatory authorities, we are prohibited from marketing and promoting the products for indications that are not specifically approved by the regulatory authorities. These “off-label” uses are common across medical specialties and may constitute an appropriate treatment for some patients in varied circumstances. Regulatory authorities in the United States and in other jurisdictions generally do not restrict or regulate the behavior of physicians in their choice of treatment within the practice of medicine. Regulatory authorities do, however, restrict communications by biotechnology or pharmaceutical companies on off-label use. If the FDA or another regulator determines that our promotional activities constitute promotion of an off-label use, it could request that we modify our promotional materials and subject us to regulatory or enforcement actions as well as actions by other agencies, including issuance of warning letters or untitled letters, suspension or withdrawal of an approved product from the market, mandatory or voluntary recalls, and could result in the imposition of significant criminal, civil, and administrative penalties such as civil fines, disgorgement of money, imprisonment, exclusion from participation in federal health care programs (e.g. Medicare and Medicaid), operating restrictions, additional reporting requirements and/or oversight if we become subject to a corporate integrity agreement or similar agreement, injunctions or criminal prosecution, any of which could significantly harm our business.

Current and future legislation may affect the prices we may obtain for currently marketed products or future product candidates.

In the United States and some foreign jurisdictions, there have been a number of legislative and regulatory changes and proposed changes regarding the healthcare system that could prevent or delay marketing approval of our product candidates, restrict post-approval activities and affect our ability to sell profitably any product candidates for which we obtain marketing approval.

In the United States, Medicare covers certain drug purchases by the elderly and eligible disabled people and introduced a reimbursement methodology based on average sales prices for physician-administered drugs. In addition, Medicare may limit the number of drugs that will be covered in any therapeutic class. Ongoing cost reduction initiatives and future laws could decrease the coverage and price that we will receive for any approved products. While Medicare beneficiaries are limited to most elderly and certain disabled individuals, private payors often follow Medicare coverage policy and payment limitations in setting their own payment rates.

In March 2010, the ACA became law. The ACA is a sweeping law intended to broaden access to health insurance, reduce or constrain the growth of healthcare spending, enhance remedies against fraud and abuse, add new transparency requirements for the healthcare and health insurance industries, impose new taxes and fees on the health industry and impose additional health policy reforms. Among the provisions of the ACA of importance to our product candidates are the following:

33

There remain challenges to certain aspects of the ACA, and we expect there will be additional challenges and amendments to the ACA in the future. Since January 2017, President Trump has several two Executive Orders and other directives designed to eliminate the implementation of certain provisions of the ACA or otherwise circumvent some of the requirements for health insurance mandated by the ACA. Congress has also considered legislation that would repeal or repeal and replace all or part of the ACA. While Congress has not passed comprehensive repeal legislation, several bills affecting the implementation of certain taxes under the ACA have been signed into law. The legislation enacted in 2017, informally titled the Tax Cuts and Jobs Act, among other things, included a provision which repealed, effective January 1, 2019, the tax-based shared responsibility payment imposed by the ACA on certain individuals who fail to maintain qualifying health coverage for all or part of a year that is commonly referred to as the “individual mandate”. In addition, the 2020 federal spending package permanently eliminated, effective January 1, 2020, the ACA-mandated “Cadillac” tax on certain high-cost employer-sponsored health insurance plans and the medical device excise tax on non-exempt medical devices and, effective January 1, 2021, also eliminates the health insurer tax. On December 14, 2018, a Texas U.S. District Court Judge ruled that the ACA is unconstitutional in its entirety because the “individual mandate” was repealed by Congress as part of the Tax Cuts and Jobs Act. Additionally, on December 18, 2019, the U.S. Court of Appeals for the 5th Circuit upheld the District Court ruling that that the individual mandate was unconstitutional and remanded the case back to the District Court to determine whether the remaining provisions of the ACA are invalid as well. On March 2, 2020, the United States Supreme Court granted the petitions for writs of certiorari to review this case. It is unclear how such litigation and other efforts to repeal and replace the ACA will impact the ACA.

There has also been heightened governmental scrutiny over the manner in which manufacturers set prices for their marketed products, which has resulted in several Congressional inquiries and proposed bills designed to, among other things, bring more transparency to product pricing, review the relationship between pricing and manufacturer patient programs, and reform government program reimbursement methodologies for drug products. For example, the Trump administration’s budget proposal for fiscal year 2021 includes a $135 billion allowance to support legislative proposals seeking to reduce drug prices, increase competition, lower out-of-pocket drug costs for patients, and increase patient access to lower-cost generic and biosimilar drugs. On March 10, 2020, the Trump administration sent “principles” for drug pricing to Congress, calling for legislation that would, among other things, cap Medicare Part D beneficiary out-of-pocket pharmacy expenses, provide an option to cap Medicare Part D beneficiary monthly out-of-pocket expenses, and place limits on pharmaceutical price increases. Further, the Trump administration previously released a “Blueprint” to lower drug prices and reduce out of pocket costs of drugs that contains additional proposals to increase drug manufacturer competition, increase the negotiating power of certain federal healthcare programs, incentivize manufacturers to lower the list price of their products, and reduce the out of pocket costs of drug products paid by consumers. The Department of Health and Human Services, or HHS, has solicited feedback on some of these measures and has implemented others under its existing authority. On July 24, 2020, the Trump administration announced four executive orders related to prescription drug pricing that attempt to implement several of the administration’s proposals, including a policy that would tie Medicare Part B drug prices to international drug prices; one that directs HHS to finalize the Canadian drug importation proposed rule previously issued by HHS and makes other changes allowing for personal importation of drugs from Canada; one that directs HHS to finalize the rulemaking process on modifying the anti-kickback law safe harbors for discounts for plans, pharmacies, and pharmaceutical benefit managers; and one that reduces costs of insulin and epipens to patients of federally qualified health centers. While some of these and other measures may require additional authorization to become effective. Congress and the Trump administration have each indicated that it will continue to seek new legislative and/or administrative measures to control drug costs. Individual states in the United States have also become increasingly active in passing legislation and implementing regulations designed to control pharmaceutical product pricing, including price or patient reimbursement constraints, discounts, restrictions on certain product access and marketing cost disclosure and transparency measures, and, in some cases, designed to encourage importation from other countries and bulk purchasing.

We expect that the ACA, as well as other healthcare reform measures that may be adopted in the future, may result in more rigorous coverage criteria and in additional downward pressure on the price that we will receive for any approved product. Further, it is possible that additional governmental action is taken in response to the COVID-19 pandemic. For example, on August 6, 2020, the Trump administration issued another executive order that instructs the federal government to develop a list of “essential” medicines and then buy them and other medical supplies from U.S. manufacturers instead of from companies around the world, including China. The order is meant to reduce regulatory barriers to domestic pharmaceutical manufacturing and catalyze

34

manufacturing technologies needed to keep drug prices low and the production of drug products in the United States. Any reduction in payments from Medicare or other government programs may result in a similar reduction in payments from private payors. The implementation of cost containment measures or other healthcare reforms may prevent us from being able to generate revenues, attain profitability, or commercialize our products.

Our product and future product candidates may become subject to unfavorable pricing regulations, third-party reimbursement practices or healthcare reform initiatives, which would harm our business.

Our ability to commercialize RUCONEST^® or any other product candidate successfully also will depend in part on the extent to which coverage and adequate reimbursement for these products and related treatments will be available from government health administration authorities, private health insurers and other organizations. Government authorities and other third-party payors, such as private health insurers and health maintenance organizations, decide which medications they will pay for and establish reimbursement levels. A primary trend in the U.S. and E.U. healthcare industries and elsewhere is cost containment. Government authorities and other third-party payors have attempted to control costs by limiting coverage and the amount of reimbursement for particular medications. Increasingly, third-party payors are requiring that drug companies provide them with predetermined discounts from list prices and are challenging the prices charged for medical products. We cannot be certain that coverage and reimbursement will continue to be available for RUCONEST^® or any other product that we commercialize and, if coverage and reimbursement is available, the level of reimbursement. Reimbursement may impact the demand for, or the price of, any product candidate for which we obtain marketing approval. In addition, third-party payors are likely to impose strict requirements for reimbursement of a higher priced drug, and any launch of a competitive product is likely to create downward pressure on the price initially charged. If reimbursement is not available or is available only to a limited degree, we may not be able to successfully commercialize any product candidate for which we obtain marketing approval.

There may be significant delays in obtaining coverage and reimbursement for newly approved drugs, and coverage may be more limited than the purposes for which the drug is approved by the applicable regulatory authority. Moreover, eligibility for coverage and reimbursement does not imply that any drug will be paid for in all cases or at a rate that covers our costs, including research, development, intellectual property, manufacturing, sale and distribution expenses. Interim reimbursement levels for new drugs, if applicable, may also not be sufficient to cover our costs and may not be made permanent. Reimbursement rates may vary according to the use of the drug and the clinical setting in which it is used, may be based on reimbursement levels already set for lower cost drugs, and may be incorporated into existing payments for other services. Net prices for drugs may be reduced by mandatory discounts or rebates required by government healthcare programs or private payors and by any future relaxation of laws that presently restrict imports of drugs from countries where they may be sold at lower prices than in the United States. In the United States, third-party payors often rely upon Medicare coverage policy and payment limitations in setting their own reimbursement policies. In the European Union, reference pricing systems and other measures may lead to cost containment and reduced prices. Our inability to promptly obtain coverage and adequate reimbursement rates from both government-funded and private payors for any approved products that we develop could have a material adverse effect on our operating profit, our ability to raise capital needed to develop product candidates and commercialize products and our overall financial condition.

We are exposed to the risk that our employees and independent contractors, including principal investigators, consultants, any future commercial collaborators, service providers and other vendors may engage in misconduct or other illegal activity.

Our employees and independent contractors, including principal investigators, consultants, commercial collaborators, service providers and other vendors may also engage in misconduct or other improper activities, including noncompliance with regulatory standards and requirements, which could have an adverse effect on our results of operations. We are exposed to the risk that our employees and independent contractors, including principal investigators, consultants, any future commercial collaborators, service providers and other vendors may engage in misconduct or other illegal activity. Misconduct by these parties could include intentional, reckless and/or negligent conduct or other unauthorized activities that violate the laws and regulations of the FDA and other similar regulatory bodies, including those laws that require the reporting of true, complete and accurate information to such regulatory bodies; manufacturing standards; U.S. federal and state healthcare fraud and abuse laws, data privacy and security laws and other similar non-U.S. laws; or laws that require the true, complete and accurate reporting of financial information or data. In particular, sales, marketing and business arrangements in the healthcare industry are subject to extensive laws and regulations intended to prevent fraud,

35

misconduct, kickbacks, self-dealing and other abusive practices. These laws and regulations restrict or prohibit a wide range of pricing, discounting, marketing and promotion, sales commission, customer incentive programs, and other business arrangements. Such misconduct also could involve the improper use or misrepresentation of individually identifiable information, including, without limitation, information obtained in the course of clinical trials, the creation of fraudulent data in our preclinical studies or clinical trials, or illegal misappropriation of product, which could result in regulatory sanctions and cause serious harm to our reputation. It is not always possible to identify and deter misconduct by employees and other third-parties, and the precautions we take to detect and prevent this activity may not be effective in controlling unknown or unmanaged risks or losses or in protecting us from governmental investigations or other actions or lawsuits stemming from a failure to be in compliance with such laws or regulations. In addition, we are subject to the risk that a person or government could allege such fraud or other misconduct, even if none occurred. If any such actions are instituted against us, and we are not successful in defending ourselves or asserting our rights, those actions could have a significant impact on our business and financial results, including, without limitation, the imposition of significant civil, criminal and administrative penalties, damages, monetary fines, disgorgement, possible exclusion from participation in Medicare, Medicaid and other U.S. federal healthcare programs or healthcare programs in other jurisdictions, integrity oversight and reporting obligations to resolve allegations of non-compliance, imprisonment, other sanctions, contractual damages, reputational harm, diminished profits and future earnings and curtailment of our operations, any of which could adversely affect our ability to operate our business and our results of operations.

As a “foreign private issuer,” we are exempt from a number of rules under the U.S. securities laws and the Nasdaq rules, and we are permitted to file less information with the SEC than are U.S. companies. In addition, we are permitted and expect to follow certain home country corporate governance practices in lieu of certain Nasdaq requirements applicable to domestic issuers. This may make our ADSs and ordinary shares less attractive to investors.

We are a “foreign private issuer,” as defined in the rules and regulations of the SEC, and, consequently, we are not subject to all of the disclosure requirements applicable to 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. 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, we are not required to file periodic reports and financial statements with the SEC as frequently or as promptly as U.S. public companies. Accordingly, there may be less publicly available information concerning our company than there is for U.S. public companies.

As a foreign private issuer traded on Euronext Amsterdam, we are permitted to follow certain home country corporate governance practices in lieu of certain Nasdaq requirements. The rights of holders of ordinary shares and, therefore, certain of the rights of holders of the ADSs, are governed by Dutch law, including the provisions of the Dutch Corporate Governance Code, and by our Articles of Association, which may provide less protection than is afforded to investors under Nasdaq rules applicable to domestic issuers.

In particular, we expect to follow Dutch law instead of Nasdaq practice in the following ways:

Although we may rely on certain home country corporate governance practices, we must comply with Nasdaq Rule 5625, Notification of Noncompliance and Rule 5640, Voting Rights. Further, we must have an audit committee that satisfies Rule 5605(c)(3), which addresses audit committee responsibilities and authority, and that consists of committee members who meet the independence requirements of Rule 5605(c)(2)(A)(ii).

36

We intend to take all actions necessary to maintain compliance as a foreign private issuer under the applicable corporate governance requirements of the Sarbanes-Oxley Act, the rules adopted by the SEC and the Nasdaq corporate governance rules and listing standards.

The United Kingdom’s withdrawal from the European Union, or Brexit, could result in increased regulatory and legal complexity, and impose additional challenges in securing regulatory approval of our product candidates in the European Union and the rest of Europe.

The United Kingdom withdrew from the European Union effective as of January 31, 2020 and is now in a period of transition until the end of 2020. The transition period maintains all existing trading arrangements. During the transition period, the United Kingdom and the European Union will negotiate future trading arrangements. Until a final agreement has been reached, an exit without a trade agreement in place, which would result in the United Kingdom losing access to free trade agreements for goods and services with the European Union and other countries, continues to be a risk. An exit by the United Kingdom from the European Union without an agreement in place would likely lead to legal uncertainty and potentially divergent laws and regulations between the United Kingdom and the European Union. We cannot predict whether or not the United Kingdom will significantly alter its current laws and regulations in respect of the pharmaceutical industry and, if so, what impact any such alteration would have on us or our business. Moreover, we cannot predict the impact that Brexit will have on (i) the marketing of pharmaceutical products, (ii) the process to obtain regulatory approval in the United Kingdom for product candidates or (iii) the award of exclusivities that are normally part of the European Union legal framework.

Brexit may also result in a reduction of funding to the EMA if the United Kingdom no longer makes financial contributions to European institutions, such as the EMA. If the United Kingdom funding is so reduced, it could create delays in the EMA issuing regulatory approvals for our products and product candidates and, accordingly, have a material adverse effect on our business, financial position, results of operations and future growth prospects.

As a result of Brexit, other European countries may seek to conduct referenda with respect to their continuing membership with the European Union. Given these possibilities and others we may not anticipate, as well as the absence of comparable precedent, it is unclear what financial, regulatory and legal implications the withdrawal of the United Kingdom from the European Union would have and how such withdrawal would affect us, and the full extent to which our business could be adversely affected.

In addition, following the Brexit vote, the European Union decided to move the headquarters of the EMA from the United Kingdom to the Netherlands. The EMA is currently finishing its relocation process to the Netherlands. However, as a result of the move, the EMA has lost a significant percentage of its employees and was not able to hire at least the same amount of employees that left the EMA upon the movement of its headquarters from the United Kingdom to the Netherlands. This raises the possibility that new drug approvals in the European Union could be delayed as a result of such employee shortage.

Risks Related to Our ADSs

We are an “emerging growth company,” and the reduced disclosure requirements applicable to emerging growth companies may make our ADSs less attractive to investors and, as a result, adversely affect the price of the ADSs and result in a less active trading market for the ADSs.

We are an emerging growth company as defined in the JOBS Act, and we may take advantage of certain exemptions from various reporting requirements that are applicable to other public companies that are not emerging growth companies. These exemptions include:

37

We may choose to take advantage of some, but not all, of the available exemptions. For example, in this prospectus, we have elected to rely on the exemption from the auditor attestation requirement and the exemption that permits only two years of financial statements to be presented. We may avail ourselves of these disclosure exemptions until we are no longer an emerging growth company. We cannot predict whether investors will find our ADSs less attractive because of our reliance on some or all of these exemptions. If investors find our ADSs less attractive, it may adversely affect the price of the ADSs and there may be a less active trading market for the ADSs.

We will cease to be an emerging growth company upon the earliest of:

In addition, under the JOBS Act, emerging growth companies can delay adopting new or revised accounting standards issued subsequent to the enactment of the JOBS Act until such time as those standards apply to private companies. We have irrevocably elected not to avail ourselves of this exemption from new or revised accounting standards and, therefore, will be subject to the same new or revised accounting standards as other public companies that are not emerging growth companies. If we are unable to comply timely with these accounting standards, we may be delayed in providing the disclosures required by the Exchange Act.

If securities or industry analysts do not publish research or reports about our business, or if they change their recommendations regarding the ADSs adversely, the price and/or trading volume of our ADSs could be affected.

The trading market for our ADSs may be influenced by the research and reports that industry or securities analysts publish about us or our business. If one or more of the analysts who cover us or our industry downgrade the shares in a research report, the market price of the shares may decline and if one or more of these analysts ceases coverage of us or fails to publish reports on us regularly, we could lose visibility in the financial markets, which could cause the market price and/or trading volume of the shares to decline.

If intangible assets and goodwill that we record in connection with our acquisitions become impaired, we may have to take significant charges against earnings.

In connection with the accounting for our acquisitions, a significant value may be recognized in respect of intangible assets, including developed technology and customer relationships relating to the acquired product lines, and goodwill. Under IFRS, we must assess, at least annually and potentially more frequently, whether the value of intangible assets and goodwill has been impaired. Intangible assets and goodwill will be assessed for impairment in the event of an impairment indicator. Any reduction or impairment of the value of intangible assets and goodwill will result in a charge against earnings, which could materially adversely affect our results of operations and shareholders’ equity in future periods.

38

Our global operations subject us to significant tax risks.

We are subject to tax rules in the jurisdictions in which we operate. Changes in tax rates, tax relief and tax laws, changes in practice or interpretation of the law by the relevant tax authorities, increasing challenges by relevant tax authorities or any failure to manage tax risks adequately could result in increased charges, financial loss, penalties and reputational damage. Tax authorities may actively pursue additional taxes based on retroactive changes to tax laws which could result in a material restatement to its tax position. Any of these factors could have a negative impact on our business, financial condition, results of operations and prospects.

Exchange rate fluctuations may materially affect our results of operations and financial condition.

Owing to the international scope of our operations, fluctuations in exchange rates, particularly between the Euro and the U.S. dollar, may adversely affect us. While we are based in the Netherlands, we source materials, products and services from several countries outside the EU that are paid in local currencies. As a result of the commercialization of RUCONEST^® in the United States and in other countries outside the EU, we will also receive payments and generate costs in U.S. dollars and other currencies. As a result, our business and the price of our ADSs may be affected by fluctuations in foreign exchange rates between the Euro and the U.S. dollar, as well as other currencies.

Currency fluctuations may adversely affect the price of our ADSs.

Our ordinary shares are quoted in euros on Euronext Amsterdam, and our ADSs will be quoted in U.S. dollars on the Nasdaq. Movements in the euro/U.S. dollar exchange rate may adversely affect the U.S. dollar price of the ADSs on the Nasdaq or the euro price on Euronext Amsterdam. For example, if the euro weakens against the U.S. dollar, the U.S. dollar price of our ADSs could decline, even if the price of our ordinary shares in euros increases or remains unchanged.

The price and trading volume of our ADSs and ordinary shares may be volatile, and purchasers of our ADSs or ordinary shares could incur substantial losses.

The market price of our ADSs is likely to be volatile and could decline significantly. The stock market in general, and the market for biotechnology and emerging pharmaceutical companies in particular, have experienced extreme volatility that has often been unrelated to the operating performance of particular companies. The market price for our ADSs and ordinary shares may be influenced by a variety of factors, including:

39

These and other market and industry factors may cause the market price and demand for our ADSs and ordinary shares to fluctuate substantially.

Moreover, stocks of life science companies, and stock markets in general, have from time to time experienced extreme price and volume fluctuations that may be unrelated or disproportional to the operational performance of any particular companies. In addition, the trading prices for common stock of other biopharmaceutical companies have been highly volatile as a result of the COVID-19 pandemic. The COVID-19 outbreak continues to rapidly evolve. The extent to which the outbreak may impact our business, and the prices of our ADSs and ordinary shares will depend on future developments, which are highly uncertain and cannot be predicted with confidence.

We will incur increased costs as a result of simultaneously having our ADSs listed in the United States and our ordinary shares admitted to trading on Euronext Amsterdam in the Netherlands, and our senior management will be required to devote substantial time to new compliance initiatives and corporate governance practices.

As a company whose securities are publicly listed in the United States, and particularly after we no longer qualify as an emerging growth company, or EGC, we will incur significant legal, accounting and other expenses that we did not incur previously, even though our ordinary shares are admitting to trading on Euronext Amsterdam. For example, the Sarbanes-Oxley Act of 2002, the Dodd-Frank Wall Street Reform and Consumer Protection Act, the listing requirements of Nasdaq and other applicable U.S. securities rules and regulations impose various requirements on non-U.S. reporting public companies, including the establishment and maintenance of effective disclosure and financial controls and corporate governance practices. Our senior management and other personnel will need to devote a substantial amount of time to these compliance initiatives. Moreover, these rules and regulations will increase our legal and financial compliance costs and will make some activities more time-consuming and costly. For example, we expect that these rules and regulations may make it more difficult and more expensive for us to obtain director and officer liability insurance, which in turn could make it more difficult for us to attract and retain qualified senior management personnel or members for our board of directors.

However, these rules and regulations are often subject to varying interpretations, in many cases due to their lack of specificity, and, as a result, their application in practice may evolve over time as new guidance is provided by regulatory and governing bodies. This could result in continuing uncertainty regarding compliance matters and higher costs necessitated by ongoing revisions to disclosure and governance practices.

Pursuant to Section 404 of the Sarbanes-Oxley Act of 2002, or Section 404, regardless of whether or not we are an EGC we will be required to furnish a report by our senior management on our internal control over financial reporting, beginning with our annual report filed with the SEC for the year ending December 31, 2021, which we expect to file by April 2022. However, while we remain an EGC we will not be required to include an attestation report on internal control over financial reporting issued by our independent registered public accounting firm. To prepare for eventual compliance with Section 404, including the attestation report required once we no longer qualify as an EGC, we will be engaged in a process to document and evaluate our internal control over financial reporting, which is both costly and challenging. In this regard, we will need to continue to dedicate internal resources, potentially engage outside consultants, adopt a detailed work plan to assess and document the adequacy of internal control over financial reporting, continue steps to improve control processes as appropriate, validate through testing that controls are functioning as documented, and implement a continuous reporting and improvement process for internal control over financial reporting. Despite our efforts, there is a risk that we will not be able to conclude, within the prescribed timeframe or at all, that our internal control over financial reporting is effective as required by Section 404.

Further, being a U.S. listed company and a Dutch public company with ordinary shares admitted to trading on Euronext Amsterdam impacts the disclosure of information and requires compliance with two sets of applicable rules. From time to time, this may result in uncertainty regarding compliance matters and result in higher costs necessitated by legal analysis of dual legal regimes, ongoing revisions to disclosure and adherence to heightened

40

governance practices. As a result of the enhanced disclosure requirements of the U.S. securities laws, business and financial information that we report is broadly disseminated and highly visible to investors, which we believe may increase the likelihood of threatened or actual litigation, including by competitors and other third parties, which could, even if unsuccessful, divert financial resources and the attention of our management and key employees from our operations.

We have identified material weaknesses in our internal control over financial reporting. If we are unable to remediate these material weaknesses, or if we identify additional material weaknesses in the future or otherwise fail to maintain an effective system of internal controls, we may not be able to accurately or timely report our financial condition or results of operations, which may adversely affect our business and stock price.

We have identified material weaknesses in the design and operating effectiveness of our internal control over financial reporting. A material weakness is a deficiency, or a combination of deficiencies, in internal control over financial reporting, such that there is a reasonable possibility that a material misstatement of our annual or interim financial statements will not be prevented or detected on a timely basis. If we are unable to remediate these material weaknesses, or if we identify additional material weaknesses in the future or otherwise fail to maintain an effective system of internal controls, we may not be able to accurately or timely report our financial condition or results of operations, which may adversely affect investor confidence in us and, as a result, our stock price.

We cannot assure you that the measures we have taken to date, and actions we may take in the future, will be sufficient to remediate the control deficiencies that led to the material weaknesses in our internal control over financial reporting or that they will prevent or avoid potential future material weaknesses. In addition, neither our management nor an independent registered public accounting firm has performed an evaluation of our internal control over financial reporting in accordance with the provisions of the Sarbanes-Oxley Act. Had we or our independent registered public accounting firm performed an evaluation of our internal control over financial reporting in accordance with the provisions of the Sarbanes-Oxley Act, additional significant deficiencies or material weaknesses may have been identified.

In connection with the audits of our financial statements, we have identified material weaknesses in our internal control over financial reporting across the principles for each component of the COSO framework at the entity level and accordingly, across the business and IT processes of the Company. Although the Company does have oversight and compliance processes in place, these processes are currently not sufficiently formalized as controls to identify and address the risks of material misstatements and risks arising from IT. Where such control activities exist, there is not formalized control descriptions for our relevant controls to evaluate the design and operating effectiveness of such controls. In addition, where control activities are dependent on Information Used in a Control, the Company does not perform or document controls to determine the completeness and accuracy of such information. We also did not have controls in place to monitor control activities and identified control deficiencies.

As a result, we have identified material weaknesses in the control environment, risk assessment, monitoring, information & communication and control activities of the entity. In addition, the company did not maintain a sufficient complement of accounting and financial reporting resources commensurate with the financial reporting requirements. Deficiencies in control activities contributed to the potential for there to have been material accounting errors in substantially all financial statements account balances and disclosures.

We are in the process of remediating the material weaknesses identified including further developing and implementing formal policies, processes, internal controls and documentation relating to our financial reporting. We are also currently in the process of finalizing a risk assessment framework and scoping to identify key processes and controls that will require additional enhanced controls to be designed and implemented.

Future sales of our ordinary shares or ADSs, or the perception that such sales may occur, could depress the prices of such ordinary shares or ADSs.

Sales of a substantial number of our ADSs in the public market, or the perception that these sales might occur, could depress the market price of the ADSs and could impair our ability to raise capital through the sale of

41

additional equity securities. We are unable to predict the effect that such sales may have on the prevailing market price of our ADSs.

Holders of our ADSs have fewer rights than our shareholders and are subject to certain additional risks.

ADS holders do not hold ordinary shares directly and, as such, are subject to, among others, the following additional risks:

An active and liquid market for our securities may fail to develop, which could harm the market price of our ADSs.

There is currently no public market on a U.S. national securities exchange for our ADSs or our ordinary shares. Although our ADSs have been approved for listing on the Nasdaq, an active trading market for our ADSs may never develop or be sustained. In the absence of an active trading market for our ADSs, investors may not be able to sell their ADSs at the time that they would like to sell.

We are a Dutch public company with limited liability. The rights of our shareholders and ADS holders may be different from the rights of shareholders in companies governed by the laws of U.S. jurisdictions and may not protect investors in a similar fashion afforded by incorporation in a U.S. jurisdiction.

We are a public company (naamloze vennootschap) organized under the laws of the Netherlands. Our corporate affairs are governed by our articles of association, the rules of our board of directors and by the laws governing companies incorporated in the Netherlands. However, there can be no assurance that Dutch law will not change in the future or that it will serve to protect investors in a similar fashion afforded under corporate law principles in the United States, which could adversely affect the rights of investors.

The rights of shareholders and ADS holders and the responsibilities of directors may be different from the rights and obligations of shareholders, ADS holders and directors in companies governed by the laws of U.S. jurisdictions. In the performance of their duties, our directors are required by Dutch law to consider the interests of our company, its shareholders, its employees and other stakeholders, in all cases with due observation of the principles of reasonableness and fairness. It is possible that some of these parties will have interests that are different from, or in addition to, your interests as an ADS holder.

For more information on relevant provisions of Dutch corporation law and of our articles of association, see “Description of Share Capital and Articles of Association” and “Comparison of Dutch Corporate Law and U.S. Corporate Law.”

Provisions of our Articles of Association or Dutch corporate law might deter acquisition bids for us that might be considered favorable and prevent, delay or frustrate any attempt to replace or remove the members of our board of directors.

Under Dutch law, various protective measures are possible and permissible within the boundaries set by Dutch law and Dutch case law.

Certain provisions of our articles of association may make it more difficult or less attractive for a third party to acquire control of us or to effect a change in our board of directors. These provisions include: a provision that our

42

directors are appointed on the basis of a binding nomination prepared by our board of directors which can only be overruled by a simple majority of votes cast representing at least one third of our issued share capital; a provision that our directors may only be removed by the general meeting of shareholders by a simple majority of votes cast representing at least one third of our issued share capital; and a requirement that certain matters, including an amendment of our articles of association, may only be brought to our shareholders for a vote upon a proposal by our board of directors. Currently we have no such protective measures in place.

Shareholders and ADS holders may not be able to exercise preemptive rights and, as a result, may experience substantial dilution upon future issuances of ordinary shares.

In the event of an issuance of ordinary shares, subject to certain exceptions, each shareholder will have a pro rata preemptive right in proportion to the aggregate nominal value of the ordinary shares held by such holder. These preemptive rights may be restricted or excluded by a resolution of the general meeting or by another corporate body designated by the general meeting. This could cause existing shareholders to experience substantial dilution of their interest in us.

We are not obligated to, and do not, comply with all best practice provisions of the Dutch Corporate Governance Code.

We are subject to the Dutch Corporate Governance Code, or the DCGC. The DCGC contains both principles and best practice provisions for boards of directors, shareholders and general meetings, auditors, disclosure, compliance and enforcement standards. As a Dutch company listed on a stock exchange, we are subject to the DCGC and are required to disclose in our annual board report to what we extent comply with the principles and best practice provisions of the DCGC, and where we do not (for example, because of a conflicting Nasdaq requirement or otherwise), we must state why and to what extent we deviate in our annual report. We do not comply with all best practice provisions of the DCGC. See “Description of Share Capital and Articles of Association.” This may affect your rights as a shareholder or ADS holder and you may not have the same level of protection as a shareholder or ADS holder in a Dutch company that fully complies with the DCGC.

We have never declared or paid dividends on our ordinary shares since our ordinary shares were listed on Euronext Amsterdam, and we do not anticipate paying dividends in the foreseeable future.

We have never declared or paid cash dividends on our ordinary shares since our ordinary shares were listed on Euronext Amsterdam. We intend to retain any earnings for use in our business and do not currently intend to pay dividends on our ordinary shares. Subject to restrictions under applicable law, any future determination to pay dividends or other distribution will be at the discretion of our board of directors and will depend upon a number of factors, including our results of operations, cash requirements, financial condition, future prospects, contractual restrictions, any future debt agreements, restrictions under applicable laws and other factors that our board of directors may deem relevant. We do not anticipate paying any cash dividends or other distributions on our ordinary shares in the foreseeable future. As a result, a return on any investment will only occur if the price of our ordinary shares increases.

ADS holders may not receive distributions on the ordinary shares represented by our ADSs or any value for such distribution if it is illegal or impractical to make them available to ADS holders.

While we do not anticipate paying any dividends or other distributions on our ordinary shares in the foreseeable future, if such a dividend or distribution is declared, the depositary for the ADSs has agreed to pay to you the cash dividends or other distributions it or the custodian receives on our ordinary shares or other deposited securities after deducting its fees and expenses, including withholding taxes. You will receive these distributions in proportion to the number of ordinary shares your ADSs represent. However, in accordance with the limitations set forth in the deposit agreement, it may be unlawful or impractical to make a distribution available to ADS holders. We have no obligation to take any other action to permit the distribution of the ADSs, ordinary shares, rights or anything else to holders of our ADSs. This means that you may not receive the distributions we make on our ordinary shares or any value from them if it is unlawful or impractical to make them available to you. These restrictions may have a material adverse effect on the value of your ADSs.

43

Dividends distributed by us on the ordinary shares or ADSs to certain related parties in low-taxed jurisdictions might in the future become subject to an additional Dutch withholding tax on dividends.

Under current Dutch tax law, dividends paid on ordinary shares or ADSs are in principle subject to Dutch dividend withholding tax at a rate of 15% under the Dutch Dividend Withholding Tax Act 1965 (Wet op de dividendbelasting 1965), unless a domestic or treaty exemption or reduction applies. In a letter to the Dutch parliament dated May 29, 2020, the Dutch State Secretary for Finance announced that the Dutch government intends to introduce an additional withholding tax on dividends paid to related entities in jurisdictions that have a corporate tax rate below 9% or to jurisdictions included on the EU’s blacklist of non-cooperative jurisdictions and in certain abusive situations, effective January 1, 2024. On September 25, 2020, the Dutch government launched an internet consultation to give interested parties the opportunity to respond to the draft legislative proposal to introduce the conditional withholding tax on dividends. Pursuant to the proposal published for consultation purposes, the conditional withholding tax on dividend payments will be an addition to the recently passed conditional withholding tax on interest and royalty payments pursuant to the Dutch Withholding Tax Act 2021 (Wet bronbelasting 2021), which act will become effective January 1, 2021. It is possible that the rate will be as high as the highest Dutch corporate income tax rate (currently 25%) at the time of the dividend payment, which will be the statutory rate applicable to interest and royalty payments to related entities in jurisdictions that have a corporate tax rate below 9% or to jurisdictions included on the EU’s blacklist of non-cooperative jurisdictions and in certain abusive situations. At the same time, the current Dutch dividend withholding tax regime is anticipated to remain in place. However, if the dividend withholding tax and the conditional withholding tax on dividends cumulate, the conditional withholding tax will be reduced by the dividend withholding tax levied. As a result, if the shareholder being a related entity is established in a jurisdiction that has a corporate tax rate below 9% or in a jurisdiction included on the EU’s blacklist of non-cooperative jurisdictions, the tax rate on dividends may rise from 15% to 25%. The internet consultation closes on October 23, 2020. After the internet consultation, the Dutch government aims to prepare the final legislative proposal in early 2021.

ADS holders must act through the depositary to exercise their voting rights and, as a result, may be unable to exercise their voting rights on a timely basis.

We will not treat holders of our ADSs (rather than the ordinary shares underlying the ADSs) as shareholders, and they will not be able to exercise shareholder rights, except through our depositary and except that the ADS holders will have meeting rights to attend our general meetings. The depositary will be the holder of the ordinary shares underlying the ADSs, and ADS holders will be able to exercise voting rights with respect to the ordinary shares represented by the ADSs only in accordance with the deposit agreement relating to the ADSs. There are practical limitations on the ability of ADS holders to exercise their voting rights due to the additional procedural steps involved in communicating with these holders. For example, holders of our ordinary shares will be able to exercise their voting rights by either attending the shareholders meeting in person or voting by proxy. ADS holders, by comparison, will not receive any notice directly from us. Instead, in accordance with the deposit agreement, we will use commercially reasonable endeavors to provide at least 30 days’ notice to the depositary of any such shareholders’ meeting and details concerning the matters to be voted on in advance of the meeting date. If we so instruct, the depositary will mail to ADS holders the notice of the meeting and a statement as to the manner in which voting instructions may be given by holders as soon as practicable after receiving notice from us of any such meeting. To exercise their voting rights, ADS holders must then instruct the depositary as to voting the ordinary shares represented by their ADSs. Due to these procedural steps involving the depositary, the process for exercising voting rights may take longer for ADS holders than for holders of ordinary shares. The ordinary shares represented by ADSs for which the depositary fails to receive timely voting instructions will not be voted.

The trading of our ordinary shares on Euronext Amsterdam and of our ADSs on the Nasdaq may adversely affect the liquidity and value of our ADSs.

Our ordinary shares are traded on Euronext Amsterdam, our ADSs have been approved for listing on the Nasdaq. We cannot predict the effect of this listing on the value of our ordinary shares and ADSs. However, these arrangements may dilute the liquidity of these securities in one or more markets and may adversely affect the development of an active trading market for the ADSs in the United States or the ordinary shares on Euronext Amsterdam. The price of our ADSs could also be adversely affected by trading in our ordinary shares on Euronext Amsterdam and the price of our ordinary shares traded on Euronext Amsterdam could be adversely affected by trading in ADSs on the Nasdaq. The speed by which ADSs can be exchanged for ordinary shares and

44

subsequently traded on Euronext Amsterdam and vice versa might cause differences between the market price for an ADS and the market price for an ordinary share. Investors might arbitrate between stock exchanges to exploit such differences, exacerbating potential volatility in our market price.

ADS holders may have difficulty in effecting service of process on our company and certain directors or officers in the United States in enforcing U.S. judgements in the Netherlands or in enforcing U.S. securities laws in Dutch courts.

We are incorporated and located outside the United States and certain of our directors and officers are located outside of the United States. As a result, it may not be possible for ADS holders to effect service of process within the United States upon all such persons or our company, or to obtain discovery of relevant documents and/or the testimony of witnesses. ADS holders based in the United States may also have difficulty enforcing in courts outside the United States judgments obtained in U.S. courts against our company or our directors (including actions under the civil liability provisions of the U.S. securities laws). ADS holders may also have difficulty enforcing liabilities under the U.S. securities laws in legal actions originally brought in jurisdictions located outside the United States.

ADS holders may be subject to limitations on transfer of the ADSs.

The ADSs are only transferable on the books of the depositary. However, the depositary may close its transfer books at any time or from time to time when it deems expedient in connection with the performance of its duties. In addition, the depositary may refuse to deliver, transfer or register transfers of ADSs generally when our books or the books of the depositary are closed, or at any time if we or the depositary deem it advisable to do so because of any requirement of law or of any government or governmental body, or under any provision of the deposit agreement, or for any other reason.

Our ability to utilize our net operating loss carryforwards and to realize our deferred tax asset may be limited.

As of December 31, 2019, we had approximately € 23 million ($ 26 million) net operating loss carryforwards in the Netherlands and France and none in the U.S. These losses are reflected in a deferred tax asset of € 5.9 million ($ 6.6 million) as per December 31, 2019. Being able to utilize these losses requires that the company is sufficiently profitable and also depends on the stand-alone results of the group’s entities as the losses are ringfenced.

At the end of 2018, the group performed an internal reorganization in order to refresh part of the Dutch tax losses: certain intangibles and activities were transferred within the group resulting in a higher tax book value and relating deferred tax asset in one of the Dutch companies for the assets that have been transferred. The Dutch tax authorities might not agree to the transaction and the valuation applied, in which case e.g. (a part of) the deferred tax asset might have to be written-off. The refreshment program has been disclosed in the notes to the financial statements. The total amount of the losses available for carryforward – and the corresponding amount of the deferred tax asset – as well as the amount of the deferred tax asset relating to the intangible fixed assets depends on the acceptance of aforementioned transaction.

To the extent that we incur net operating losses in the United States, our ability to utilize our federal net operating loss carryforwards may be limited under Section 382 of the Internal Revenue Code of 1986, as amended, or the Code. The limitations apply if we experience an “ownership change,” which is generally defined as a greater than 50 percentage point change (by value) in the ownership of our equity by certain stockholders over a rolling three-year period. Similar provisions of state tax law may also apply to limit the use of our state net operating loss carryforwards. We have not assessed whether such an ownership change has previously occurred. If we have experienced an ownership change at any time since our incorporation, we may already be subject to limitations on our ability to utilize our existing net operating loss carryforwards to offset taxable income. In addition, future changes in our stock ownership, which may be outside of our control, may trigger an ownership change and, consequently, the limitations under Section 382 of the Code. As a result, if or when we earn net taxable income, our ability to use our pre-change net operating loss carryforwards to offset such taxable income may be subject to limitations, which could adversely affect our future cash flows.

45

We cannot assure you that we will not be a passive foreign investment company, or PFIC, for U.S. federal income tax purposes for any taxable year, which could result in adverse U.S. federal income tax consequences to holders of our ordinary shares.

A non-U.S. corporation will be a Passive Foreign Investment Company, or PFIC, for any taxable year if either (i) at least 75% of its gross income for such year consists of certain types of “passive” income or (ii) at least 50% of the value of its assets (generally based on an average of the quarterly values of the assets) during such year is attributable to assets that produce passive income or are held for the production of passive income. If we are a PFIC for any taxable year during which a US Holder (as defined in “Material Income Tax Considerations—Material U.S. Federal Income Tax Considerations”) holds our ordinary shares, the US Holder may be subject to adverse tax consequences, including (1) the treatment of all or a portion of any gain on disposition as ordinary income, (2) the application of an interest charge with respect to such gain and certain dividends and (3) compliance with certain reporting requirements. Based on our estimated income, assets and market capitalization for 2020, we anticipate we will not likely be a PFIC for 2020. Whether we are treated as a PFIC is a factual determination that must be made on an annual basis after the close of each taxable year. This determination will depend on, among other things, the ownership and the composition of our income and assets, as well as the value of our assets (which may fluctuate with our market capitalization) and our subsidiaries’ assets from time to time. The United States Internal Revenue Service, or IRS, or a court may disagree with our expectations. Therefore, we cannot assure you that we will not be a PFIC for the current taxable year or for any future taxable year.

If a United States person is treated as owning at least 10% of the value or voting power of our ordinary shares, such holder may be subject to adverse U.S. federal income tax consequences.

Depending upon the aggregate value and voting power of our ordinary shares that United States persons are treated as owning (directly, indirectly or constructively), we could be treated as a controlled foreign corporation, or CFC. Additionally, because our group includes one or more U.S. subsidiaries, certain of our non-U.S. subsidiaries could be treated as CFCs, regardless of whether or not we are treated as a CFC. If a United States person (as defined in the United States Internal Revenue Code of 1986, as amended) is treated as owning (directly, indirectly or constructively) at least 10% of the value or voting power of our shares, such person may be treated as a “United States shareholder” with respect to each CFC in our group (if any), which may subject such person to adverse U.S. federal income tax consequences. Specifically, a United States shareholder of a CFC may be required to report annually and include in its U.S. taxable income its pro rata share of each CFC’s “Subpart F income,” “global intangible low-taxed income” and investments of earnings in “United States property” by CFCs, whether or not we make any distributions of profits or income of a CFC to such United States shareholder. If you are treated as a United States shareholder of a CFC, failure to comply with these reporting obligations may subject you to significant monetary penalties and may prevent the statute of limitations with respect to your U.S. federal income tax return for the year for which reporting was due from starting. Additionally, a non-corporate U.S. shareholder would generally be denied certain tax deductions or foreign tax credits in respect of its income that may otherwise be allowable to a United States shareholder that is a U.S. corporation. We cannot provide any assurances that we will assist holders of our ordinary shares in determining whether we or any of our non-U.S. subsidiaries are treated as CFCs or whether any holder of our ordinary shares is treated as a United States shareholder with respect to any such CFC, nor do we expect to furnish to any United States shareholders information that may be necessary to comply with the aforementioned reporting and tax paying obligations. The Internal Revenue Service, or IRS, has provided limited guidance on situations in which investors may rely on publicly available information to comply with their reporting and taxpaying obligations with respect to foreign-controlled CFCs. U.S. holders of our ordinary shares should consult their advisors regarding the potential application of these rules to their investment in our ordinary shares.

ADS holders may not be entitled to a jury trial with respect to claims arising under the deposit agreement, which could result in less favorable results to the plaintiff(s) in any such action.

The deposit agreement governing our ADSs provides that owners and holders of ADSs irrevocably waive the right to a trial by jury in any legal proceeding arising out of or relating to the deposit agreement or the ADSs, including claims under U.S. federal securities laws, against us or the depositary to the fullest extent permitted by applicable law. As the waiver relates to claims arising as a matter of contract in relation to the ADSs, we believe that, as a matter of construction of the clause, the waiver would likely to continue to apply to ADS holders who withdraw the ordinary shares represented by the ADSs from the ADS facility with respect to claims arising before the withdrawal, and the waiver would most likely not apply to ADS holders who subsequently withdraw

46

the ordinary shares represented by ADSs from the ADS facility with respect to claims arising after the withdrawal. However, to our knowledge, the enforceability of a contractual pre-dispute jury trial waiver in connection with claims arising under the federal securities laws has not been finally adjudicated by the United States Supreme Court. If this jury trial waiver provision is prohibited by applicable law, an action could nevertheless proceed under the terms of the deposit agreement with a jury trial. Although we are not aware of a specific federal decision that addresses the enforceability of a jury trial waiver in the context of U.S. federal securities laws, it is our understanding that jury trial waivers are generally enforceable. Moreover, insofar as the deposit agreement is governed by the laws of the State of New York, New York laws similarly recognize the validity of jury trial waivers in appropriate circumstances. In determining whether to enforce a jury trial waiver provision, New York courts and federal courts will consider whether the visibility of the jury trial waiver provision within the agreement is sufficiently prominent such that a party has knowingly waived any right to trial by jury. We believe that this is the case with respect to the deposit agreement and the ADSs.

In addition, New York courts will not enforce a jury trial waiver provision in order to bar a viable setoff or counterclaim of fraud or one which is based upon a creditor’s negligence in failing to liquidate collateral upon a guarantor’s demand, or in the case of an intentional tort claim (as opposed to a contract dispute). No condition, stipulation or provision of the deposit agreement or ADSs serves as a waiver by any holder or beneficial owner of ADSs or by us or the depositary of compliance with any provision of U.S. federal securities laws and the rules and regulations promulgated thereunder.

If any owner or holder of our ADSs, including purchasers of ADSs in secondary market transactions, brings a claim against us or the depositary in connection with matters arising under the deposit agreement or the ADSs, including claims under U.S. federal securities laws, such owner or holder may incur increased costs of bringing a claim and may not be entitled to a jury trial with respect to such claims, which may have the effect of limiting and discouraging lawsuits against us or the depositary. Any legal suit, action or proceeding against or involving us brought by the Depositary or any holder or beneficial owner of ADSs, arising out of or based upon the deposit agreement, the ADSs, the ADRs or the transactions contemplated therein or thereby, may be instituted only in any state or federal court in New York, New York. Any legal suit, action or proceeding against or involving the Depositary brought by us, arising out of or based upon the Deposit Agreement, the ADSs, the ADRs or the transactions contemplated therein or thereby, may only be instituted in a state or federal court in New York, New York.

47