On November 29, 2020, Sunesis entered into the Merger Agreement with Viracta, pursuant to which, subject to the satisfaction of the conditions described in the Merger Agreement, including approval of the transaction by Sunesis’s stockholders, a wholly owned subsidiary of Sunesis will be merged with and into Viracta, with Viracta surviving the Merger as a wholly-owned subsidiary of Sunesis, referred to herein as the Merger. Additional information regarding the Merger including risk factors related to Viracta can be found in amendment No. 1 to Sunesis’ registration statement on Form S-4. Investing in our common stock involves a high degree of risk. You should carefully consider the risks and uncertainties described below and all information contained in this Annual Report on Form 10-K, as each of these risks could adversely affect our business, operating results and financial conditions. If any of the possible adverse events described below actually occurs, we may be unable to conduct our business as currently planned and our financial condition and operating results could be adversely affected. Additional risks not presently known to us or that we currently believe are immaterial may also significantly impair our business operations. In addition, the trading price of our common stock could decline due to the occurrence of any of these risks, and you may lose all or part of your investment. Please see “Special Note Regarding Forward-Looking Statements.”

Risks Related to the Merger

The Exchange Ratio is not adjustable based on the market price of our common stock so the consideration at the closing of the Merger may have a greater or lesser value than at the time the Merger Agreement was signed.

The relative proportion of the combined company that the Sunesis stockholders will own when the Merger closes will be based on the relative valuations of Sunesis and Viracta as negotiated by the parties and as specified in the Merger Agreement. Following the completion of the Merger,

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Failure to complete the Merger may result in Sunesis or Viracta paying a termination fee to the other party and could harm the common stock price of Sunesis and future business and operations of each company.

If the Merger is not completed, each of Sunesis and Viracta is subject to the following risks:

In addition, if the Merger Agreement is terminated and the board of directors of Sunesis or Viracta determines to seek another business combination, there can be no assurance that either Sunesis or Viracta will be able to find a partner willing to provide equivalent or more attractive consideration than the consideration to be provided by each party in the Merger or any partner at all.

If the conditions to the closing of the Merger are not met, the Merger may not occur.

Even if the change of control and related share issuance are approved by the stockholders of Sunesis, specified conditions must be satisfied or waived to complete the Merger. These conditions are set forth in the Merger Agreement, such as Viracta’s Pre-Closing Financing. Sunesis and Viracta cannot assure you that all of the conditions will be satisfied or waived. If the conditions are not satisfied or waived, the Merger may not occur or will be delayed, and Sunesis and Viracta each may lose some or all the intended benefits of the Merger.

The Merger may be completed even though material adverse changes may result from the announcement of the Merger, industry-wide changes and/or other causes.

In general, either Sunesis or Viracta can refuse to complete the Merger if there is a material adverse change affecting the other party between November 29, 2020, the date of the Merger Agreement, and the closing of the Merger. However, certain types of changes do not permit either party to refuse to complete the Merger, even if such change could be said to have a material adverse effect on Sunesis or Viracta, including:

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If adverse changes occur and Sunesis and Viracta still complete the Merger, the stock price of the combined company following the closing of the Merger may suffer. This in turn may reduce the value of the Merger to the stockholders of Sunesis, Viracta or both.

Some executive officers and directors of Sunesis and Viracta have interests in the Merger that are different from the respective stockholders of Sunesis and Viracta and that may influence them to support or approve the Merger without regard to the interests of the respective stockholders of Sunesis and Viracta.

Some officers and directors of Sunesis and Viracta are parties to arrangements that provide them with interests in the Merger that are different from the respective stockholders of Sunesis and Viracta, including, among others, service as an officer or director of the combined company following the closing of the Merger, severance and retention benefits, the acceleration of equity award vesting, and continued indemnification.

The market price of our common stock following the Merger may decline as a result of the Merger.

The market price of our common stock may decline as a result of the Merger for a number of reasons, including if:

Viracta and Sunesis securityholders will have a reduced ownership and voting interest in, and will exercise less influence over the management of, the combined company following the closing of the Merger as compared to their current ownership and voting interest in the respective companies.

After the completion of the Merger, the current securityholders of Viracta and Sunesis will own a smaller percentage of the combined company than their ownership in their respective companies prior to the Merger. Immediately after the Merger, it is currently estimated that Viracta equity holders as of immediately prior to the Merger (including shares issued in Viracta’s Pre-Closing Financing) will own approximately 86% of the capital stock of the combined company, with Sunesis equity holders as of immediately prior to the Merger, whose shares of our common stock will remain outstanding after the Merger, will own approximately 14% of the common stock of the combined company on a fully-diluted treasury stock method basis, calculated on a pro forma basis including after giving effect to (i) the Pre-Closing Financing by Viracta immediately prior to the effective time of the Merger, and (ii) the Merger assuming Sunesis holds $14.0 million of net cash at the closing of the Merger. These estimates are based on the anticipated Exchange Ratio and are subject to adjustment as provided in the Merger Agreement. A $7.5 million Sunesis Net Cash threshold is a condition to the completion of the Merger.

In addition, the seven member board of directors of the combined company will initially consist of six individuals with prior affiliations with Viracta and one individual with prior affiliation with Sunesis. Consequently, securityholders of Viracta and Sunesis will be able to exercise less influence over the management and policies of the combined company following the closing of the Merger than they currently exercise over the management and policies of their respective companies.

During the pendency of the Merger Agreement, Sunesis and Viracta may not be able to enter into a business combination with another party at a favorable price because of restrictions in the Merger Agreement, which could adversely affect their respective businesses.

Covenants in the Merger Agreement impede the ability of Sunesis and Viracta to make acquisitions, subject to specified exceptions relating to fiduciary duties, or complete other mergers, sales of assets or other business combinations that are not in the ordinary course of business pending completion of the Merger. As a result, if the Merger is not completed, the parties may be at a disadvantage to their competitors during that period. In addition, while the Merger Agreement is in effect, each party is generally prohibited from soliciting, initiating, encouraging or entering into specified extraordinary transactions, such as a merger, sale of assets or other business combination, with any third party, subject to specified exceptions, even if any such transaction could be favorable to such party’s stockholders.

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Certain provisions of the Merger Agreement may discourage third parties from submitting competing proposals, including proposals that may be superior to the arrangements contemplated by the Merger Agreement.

The terms of the Merger Agreement prohibit each of Sunesis and Viracta from soliciting competing proposals or cooperating with persons making unsolicited takeover proposals, except in limited circumstances when such party’s board of directors determines in good faith, after consultation with its independent financial advisor, if any, and outside counsel, that an unsolicited competing proposal constitutes, or would reasonably be expected to result in, a superior competing proposal and that failure to take such action would result in a breach of the fiduciary duties of the board of directors. In addition, if Sunesis or Viracta terminate the Merger Agreement under specified circumstances, including terminating because of a decision of a board of directors to recommend a superior competing proposal, Viracta may be required to pay Sunesis a termination fee of $1.5 million or $3.0 million or up to $250,000 in expense reimbursements or Sunesis may be required to pay Viracta a termination fee of $1.5 million, or up to $250,000 in expense reimbursements, as defined and described under the Merger Agreement. This termination fee may discourage third parties from submitting competing proposals to Sunesis or Viracta or their stockholders and may cause the respective boards of directors to be less inclined to recommend a competing proposal.

Because the lack of a public market for Viracta’s capital stock makes it difficult to evaluate the fairness of the Merger, the shareholders of Viracta may receive consideration in the Merger that is less than the fair market value of Viracta’s capital stock and/or Sunesis may pay more than the fair market value of Viracta’s capital stock.

The outstanding capital stock of Viracta is privately held and is not traded in any public market. The lack of a public market makes it extremely difficult to determine the fair market value of Viracta’s capital stock. Because the percentage of Sunesis equity to be issued to Viracta shareholders was determined based on negotiations between the parties, it is possible that the value of the our common stock to be received by Viracta shareholders will be less than the fair market value of Viracta’s capital stock, or Sunesis may pay more than the aggregate fair market value for Viracta’s capital stock.

The fairness opinion delivered by MTS Securities, LLC to the Sunesis Board prior to the entry into the Merger Agreement does not reflect changes in circumstances that may have occurred since the date of the opinion.

The Sunesis Board has not obtained an updated fairness opinion either as of the date of this proxy statement/prospectus or as of any other date subsequent to the date of the opinion from MTS Securities, LLC, an affiliate of MTS Health Partners, L.P., Sunesis’s financial advisor. Changes in circumstances, including in the operations and prospects of Sunesis or Viracta, stock prices, general market and economic conditions and other factors, some or all of which may be beyond the control of Sunesis and Viracta, including the recent coronavirus pandemic (COVID-19) that has caused higher than normal volatility in the financial markets generally, are not reflected in such opinion. The opinion does not speak as of any date other than the date of the opinion.

Because the Merger will result in an ownership change under Section 382 of the Code for Sunesis, Sunesis’s pre-Merger net operating loss (“NOL”) carryforwards and certain other tax attributes will be subject to limitations. The NOL carryforwards and other tax attributes of Viracta and of the combined organization may also be subject to limitations as a result of ownership changes.

As of December 31, 2020, Sunesis had U.S. federal NOL carryforwards and state NOL carryforwards of $475.8 million and $335.0 million, respectively. If a corporation undergoes an “ownership change” within the meaning of Section 382 of the Code (“Section 382”), the corporation’s NOL carryforwards and certain other tax attributes arising before the ownership change are subject to limitations on use after the ownership change. In general, an ownership change occurs if there is a cumulative change in the corporation’s equity ownership by certain stockholders that exceeds fifty percentage points over a rolling three-year period. Similar rules may apply under state tax laws. The Merger will result in an ownership change for Sunesis and, accordingly, Sunesis’s NOL carryforwards and certain other tax attributes will be subject to limitations (or disallowance) on their use after the Merger. Viracta’s NOL carryforwards may also be subject to limitation as a result of prior shifts in equity ownership and/or the Merger. Additional ownership changes in the future could result in additional limitations on Sunesis’s, Viracta’s and the combined organization’s NOL carryforwards. Consequently, even if the combined organization achieves profitability, it may not be able to utilize a material portion of Sunesis’s, Viracta’s or the combined organization’s NOL carryforwards and other tax attributes, which could have a material adverse effect on cash flow and results of operations. For more information on limitations on NOL carryforwards and certain other tax attributes, see “Sunesis’s ability to use NOL carryforwards to offset future taxable income, and its ability to use tax credit carryforwards, may be subject to certain limitations” below.

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Purported class action lawsuits have been filed, and additional lawsuits may be filed, relating to the Merger. An adverse ruling in any such lawsuit may prevent the Merger from being consummated.

Following announcement of the merger agreement on November 29, 2020, nine lawsuits were filed by alleged stockholders of Sunesis challenging the merger. On January 8, 2021, a lawsuit was filed by a purported stockholder of Sunesis in connection with the proposed merger between Sunesis and Viracta. The lawsuit was brought as a putative class action and captioned Mooney v. Sunesis Pharmaceuticals, Inc., et al., No. 3:21-cv-00182 (N.D. Cal.). The Mooney complaint named as defendants Sunesis, Merger Sub, Viracta and the members of the Sunesis board. The Mooney complaint alleged claims for breaches of fiduciary duty against the members of the Sunesis board, aiding and abetting breaches of fiduciary duty against Sunesis, Viracta and Merger Sub, violations of Section 14(a) of the Exchange Act and Rule 14a-9 promulgated thereunder against all defendants, and violations of Section 20(a) of the Exchange Act against the members of the Sunesis board. The plaintiff contended that the proposed merger between Sunesis and Viracta is unfair and undervalues Sunesis, and that the registration statement on Form S-4 filed on December 22, 2020 omitted or misrepresented material information regarding the proposed merger between Sunesis and Viracta, rendering the registration statement false and misleading.

Additional complaints were filed against Sunesis and the Sunesis board on January 14, 15, 16, 19, 21, and 29, 2021 (captioned Hajdini v. Sunesis Pharmaceuticals, Inc., et al., No. 1:21-cv-00359 (S.D.N.Y.); Blomquist v. Sunesis Pharmaceuticals, Inc., et al., No. 21-cv-00225 (E.D.N.Y.); Ciccotelli v. Sunesis Pharmaceuticals, Inc., et al., No. 1:21-cv-00406 (S.D.N.Y.); Zivan v. Sunesis Pharmaceuticals, Inc., et al., No. 1:21-cv-00478 (S.D.N.Y.); Rond v. Sunesis Pharmaceuticals, Inc., et al., No. 1:21-cv-00531 (S.D.N.Y.); Wheeler v. Sunesis Pharmaceuticals, Inc., et al., No. 3:21-cv-00511 (N.D. Cal.); Kubicek v. Sunesis Pharmaceuticals, Inc., et al., No. 3:21-cv-00710 (N.D. Cal.); and Sabina v. Sunesis Pharmaceuticals, Inc., et al., No. 1:21-cv-00860 (S.D.N.Y.)). The Ciccotelli and Sabina complaints additionally assert claims against Viracta and the Merger Sub. All of the complaints alleged violations of Section 14(a) and Section 20(a) of the Exchange Act. The Hajdini complaint additionally asserted a claim for breach of fiduciary duty against the board and interim Chief Executive Officer of Sunesis. All complaints sought injunctive and declaratory relief.

On February 12, 2021, Sunesis filed a Form 8-K to update and supplement the proxy statement/prospectus/information statement with additional disclosures relating to the Merger. Notices of voluntary dismissal have since been filed in all nine lawsuits. The ultimate outcome of any litigation is uncertain and unfavorable outcomes could have a negative impact on the Company’s results of operations and financial condition. It is possible that additional, similar lawsuits may be filed, or the Complaint described above will be amended. If this occurs, Sunesis does not intend to announce the filing of each additional similar complaint unless it contains allegations that are substantially distinct from those described above.

One of the conditions to completion of the Merger is the absence of any order being in effect that prohibits the consummation of the Merger. Accordingly, if any plaintiff is successful in obtaining an order enjoining consummation of the Merger, then such order may prevent the Merger from being completed, or from being completed within the expected time frame.

Risks Related to Our Business

Sunesis needs to raise substantial additional funding to continue the development of SNS-510 and any other future programs.

Sunesis will need to raise substantial additional capital to:

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Until Sunesis can generate a sufficient amount of licensing, collaboration or product revenue to finance its cash requirements, which it may never do, Sunesis expects to finance future cash needs primarily through equity issuances, debt arrangements, one or more possible licenses, collaborations or other similar arrangements with respect to development and/or commercialization rights to SNS-510, vecabrutinib, or its other development programs, or a combination of the above. Any issuance of convertible debt securities, preferred stock or common stock may be at a discount from the then-current trading price of Sunesis’s common stock. If Sunesis issues additional common or preferred stock or securities convertible into common or preferred stock, Sunesis’s stockholders will experience additional dilution, which may be significant. Further, Sunesis does not know whether additional funding will be available on acceptable terms, or at all.

In addition, the recent outbreak of the novel coronavirus known as COVID-19 has significantly disrupted global financial markets, negatively impacted U.S. market conditions and may reduce opportunities for Sunesis to seek out additional funding. Though Sunesis raised additional funds in its July 2020 offering, Sunesis will require additional financing to fund working capital and continue clinical development of SNS-510. Further decline in the market price of our common stock could make it more difficult for Sunesis to sell equity or equity-related securities in the future at a time and price that Sunesis deems appropriate.

If Sunesis fails to raise sufficient additional financing, on terms and dates acceptable to Sunesis, Sunesis may not be able to continue its operations and the development of its product candidates, and Sunesis may be required to reduce staff, reduce or eliminate research and development, slow the development of its product candidates, outsource or eliminate several business functions or shut down operations.

Sunesis has incurred losses since inception and anticipates that it will continue to incur losses for the foreseeable future. Sunesis may not ever achieve or sustain profitability.

Sunesis is not profitable and has incurred losses in each year since its inception in 1998. Sunesis’s net losses for the years ended December 31, 2020 and 2019 were $21.6 million and $23.3 million, respectively. As of December 31, 2020, Sunesis had an accumulated deficit of $704.4 million. Sunesis does not currently have any products that have been approved for marketing, and expects to incur significant losses for the foreseeable future as Sunesis continues to incur substantial development and general and administrative expenses related to its operations. Sunesis has prioritized development funding on a preclinical asset SNS-510, a PDK1 inhibitor. Sunesis has a limited number of products that are still in the early stages of development and will require significant additional investment. Sunesis’s losses, among other things, have caused and will continue to cause its stockholders’ equity and working capital to decrease.

To date, Sunesis has derived substantially all of its revenue from license and collaboration agreements. Sunesis currently has two agreements, the DOT-1 License Agreement and the Denovo Agreement, which include certain milestone and royalty payments. Sunesis cannot predict if its collaborators will continue development or whether Sunesis will receive any such payments under these agreements in the foreseeable future, or at all.

Sunesis is unable to predict when it will generate revenue from the sale of products, if at all. In the absence of additional sources of capital or partnering opportunity, which may not be available to Sunesis on acceptable terms, or at all, the development of SNS-510 or future product candidates may be reduced in scope, delayed or terminated. If Sunesis’s product candidates or those of its collaborators fail in clinical trials or do not gain regulatory approval, or if Sunesis’s future products do not achieve market acceptance, Sunesis may never become profitable. Even if Sunesis achieves profitability in the future, Sunesis may not be able to sustain profitability in subsequent periods.

There is substantial doubt about Sunesis’s ability to continue as a going concern.

Sunesis has incurred significant losses and negative cash flows from operations since its inception, and as of December 31, 2020, had cash and cash equivalents totaling $20.4 million and an accumulated deficit of $704.4 million. Sunesis expects its current cash and cash equivalents will not be sufficient to support its operations for a period of twelve months from the date its financial statements are available to be issued. Sunesis will require additional financing to fund working capital and pay its obligations as they come due. Additional financing might include one or more offerings and one or more of a combination of equity securities, debt arrangements or partnership or licensing collaborations. However, there can be no assurance that Sunesis will be successful in completing the Merger or acquiring additional funding at levels sufficient to fund its operations or on terms favorable to Sunesis. These conditions raise

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substantial doubt about Sunesis’s ability to continue as a going concern for a period of one year from the date its financial statements are available to be issued. If Sunesis is unsuccessful in its efforts to complete the Merger or raise additional financing in the near term, Sunesis will be required to significantly reduce or cease operations. The accompanying financial statements have been prepared assuming Sunesis will continue to operate as a going concern, which contemplates the realization of assets and the settlement of liabilities in the normal course of business. The consolidated financial statements do not include any adjustments to reflect the possible future effects on the recoverability and classification of assets or the amounts of liabilities that may result from uncertainty related to Sunesis’s ability to continue as a going concern.

Sunesis will continue to attempt to raise additional debt and/or equity financing to fund future operations and to provide additional working capital. However, there is no assurance that such financing will be consummated or obtained in sufficient amounts necessary to meet Sunesis’s need. If cash resources are insufficient to satisfy its on-going cash requirements, Sunesis will be required to scale back or discontinue its product development programs, or obtain funds if available (although there can be no certainties) through strategic alliances or alternatives that may require Sunesis to relinquish rights to its technology, substantially reduce or discontinue its operations entirely. No assurance can be given that any future financing will be available or, if available, that it will be on terms that are satisfactory to Sunesis, or any strategic alliances or alternatives would produce the desired results. Even if Sunesis is able to obtain additional financing, it may contain undue restrictions on its operations, in the case of debt financing, or cause substantial dilution for its stockholders, in the case of equity financing. Sunesis notes that there is significant uncertainty from the effect that the novel coronavirus may have on the availability, cost and type of financing.

The development of SNS-510 or other product candidates could be halted or significantly delayed for various reasons; Sunesis’s clinical trials for SNS-510 or other product candidates may not lead to regulatory approval.

Sunesis’s product candidates are vulnerable to the risks of failure inherent in the drug development process. Failure can occur at any stage of the development process, and successful preclinical studies and early clinical trials do not ensure that later clinical trials will be successful. A number of companies in the pharmaceutical industry have suffered significant setbacks in advanced clinical trials, even after obtaining promising results in earlier trials.

Sunesis’s product candidates may experience toxicities that in preclinical studies or in clinical trials may preclude further development, or in clinical trials may lead to a maximum tolerated dose that is not effective, or they may fail to demonstrate efficacy at the doses tested. If this were the case for SNS-510, for example, such a result would delay or prevent further development, which would severely and adversely affect Sunesis’s financial results, business and business prospects.

In the case of vecabrutinib, Sunesis decided not to move the program into Phase 2 after assessing the totality of the data including the 500 mg cohort, the highest dose studied in the trial, as Sunesis found insufficient evidence of activity in BTK inhibitor resistant-disease.

Sunesis does not know whether its current or any future clinical trials with SNS-510, vecabrutinib, or any of its product candidates will be completed on schedule, or at all, or whether its ongoing or planned clinical trials will begin or progress on the time schedule Sunesis anticipates. The commencement and completion of future clinical trials could be substantially delayed or prevented by several factors, including:

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Additionally, Sunesis’s clinical trials may be suspended or terminated at any time by the FDA, other regulatory authorities, or Sunesis itself for reasons such as change in protocol. Any failure to complete or significant delay in completing clinical trials for Sunesis’s product candidates could harm its financial results and the commercial prospects for its product candidates.

Sunesis’s business, operations, financial results and clinical development plans and timelines could be adversely impacted by the effects of health epidemics, including the recent COVID-19 pandemic, on the manufacturing, clinical trial and other business activities performed by Sunesis or by third parties with whom it conducts business, including its Contract Manufacturing Organizations (“CMOs”) Contract Research Organizations (“CROs”) and others.

Health epidemics could cause significant disruption in the operations of third-party CMOs, CROs and other third parties upon whom Sunesis relies. For example, in December 2019, a novel strain of coronavirus was reported to have surfaced in Wuhan, China. On March 11, 2020, the WHO declared COVID-19, the disease caused by the novel coronavirus, a pandemic, and on March 13, 2020, the United States declared a national emergency with respect to the coronavirus outbreak. COVID-19 has led to government-imposed quarantines, travel restrictions and other public health safety measures. As the COVID-19 pandemic continues to spread around the globe, Sunesis may experience disruptions that could severely impact its business and potential clinical trials, including:

Sunesis is still assessing the impact that COVID-19 may have on its ability to effectively conduct its business operations as planned and there can be no assurance that Sunesis will be able to avoid a material impact on its business from the spread of COVID-19 or its consequences, including disruption to its business and downturns in business sentiment generally or in its industry. For example, on March 16, 2020, San Mateo County issued a “shelter-in-place” order, effective March 17, 2020, and on March 19, 2020, the Executive Department of the State of California issued Executive Order N-33-20, ordering all individuals in the State of California to stay home or at their place of residence except as needed to maintain continuity of operations of the federal critical infrastructure sectors. Sunesis’s primary operations are located in South San Francisco, which is in San Mateo County. As a result of such county and California State orders, the majority of Sunesis’s employees have been telecommuting and continue to work from home, which may impact certain of its operations over the near term and long term.

Additionally, certain third parties with whom Sunesis engages, including its collaborators, contract organizations, third-party manufacturers, suppliers, clinical trial sites, regulators and other third parties with whom Sunesis conducts business are similarly adjusting their operations and assessing their capacity in light of the COVID-19 pandemic. If these third parties experience shutdowns

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or continued business disruptions, Sunesis’s ability to conduct its business in the manner and on the timelines presently planned could be materially and negatively impacted. For example, certain IND-enabling preclinical studies are conducted by CROs, which could be discontinued or delayed as a result of the pandemic. Sunesis and its CROs have also made certain adjustments to the operation of clinical trials in an effort to ensure the monitoring and safety of patients and minimize risks to trial integrity during the pandemic in accordance with the guidance issued by the FDA and generally, and may need to make further adjustments in the future. Many of these adjustments are new and untested, may not be effective, and may have unforeseen effects on the enrollment, progress and completion of these trials and the findings from these trials. While the current SNS-510 preclinical development is continuing, future clinical trials may be delayed. Sunesis may not be successful in opening trial sites, may experience delays in patient enrollment or in the progress of its clinical trials, may need to suspend its clinical trials, and may encounter other negative impacts to its trials, due to the effects of the COVID-19 pandemic.

The global outbreak of COVID-19 continues to rapidly evolve. While the extent of the impact of the current COVID-19 pandemic on Sunesis’s business and financial results is uncertain, a continued and prolonged public health crisis such as the COVID-19 pandemic could have a material negative impact on its business, financial condition and operating results. The extent to which the COVID-19 pandemic may impact Sunesis’s business and prospects and the overall economies of the U.S. and other countries will depend on future developments, which are highly uncertain and cannot be predicted with confidence, such as the ultimate geographic spread of the disease, the duration of the outbreak, travel restrictions and social distancing in the United States and other countries, business closures or business disruptions and the effectiveness of actions taken in the United States and other countries to contain and treat the disease.

The COVID-19 pandemic could adversely impact Sunesis’s licensees, which could cause delays in its receipts of potential milestones and royalties under Sunesis’s licensing or royalty and milestone acquisition arrangements.

As the COVID-19 pandemic continues to rapidly evolve, the companies which are working to develop and commercialize Sunesis’s licensed product candidates, such as vosaroxin and DAY101 (formerly TAK-580), could be materially and adversely affected by the risks, or the public perception of the risks, related to this pandemic, which could cause delays, suspensions or cancellations of their drug development efforts including, without limitation, their clinic trials which would correspondingly delay, suspend or negate the timing of Sunesis’s potential receipts of milestones and royalties under Sunesis’s out-licensing or royalty acquisition agreements. The disruptions to Sunesis’s licensees could include, without limitation:

The global outbreak of COVID-19 continues to rapidly evolve. The extent to which the COVID-19 pandemic may impact Sunesis’s business and prospects and the overall economies of the U.S. and other countries will depend on future developments, which are highly uncertain and cannot be predicted with confidence, such as the ultimate geographic spread of the disease, the duration of the outbreak, travel restrictions and social distancing in the United States and other countries, business closures or business disruptions and the effectiveness of actions taken in the United States and other countries to contain and treat the disease.

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Sunesis relies on a limited number of third parties to supply it with its API and FDP. If Sunesis fails to obtain sufficient quantities of these materials, the development and potential commercialization of SNS-510 and future products, if any, could be halted or significantly delayed.

Sunesis currently relies on contract manufacturing organizations (“CMOs”) for all API and FDP. Additional third-party CMOs are relied on to manufacture key starting materials and intermediates required in the manufacture of API. Sunesis has limited manufacturing experience, and Sunesis has not yet scaled-up to commercial scale. The cost to manufacture at commercial scale may materially exceed the cost of clinical-stage manufacturing.

If Sunesis’s third-party API or FDP manufacturers are unable or unwilling to produce the API or FDP it requires, Sunesis would need to establish arrangements with one or more alternative suppliers. Sunesis’s API or FDP manufacturers may encounter difficulties in achieving volume production, quality control, and quality assurance and also may experience shortages in qualified personnel and obtaining active ingredients for Sunesis’s product candidates, including delays or shortages due to limited supply or capacity of production facilities as a result of the recent COVID-19 pandemic. However, establishing a relationship with an alternative supplier would likely delay Sunesis’s ability to produce API or FDP in a timely manner. Sunesis’s ability to replace an existing manufacturer would also be challenging and time consuming because the number of potential manufacturers is limited and the FDA, EMA or other corresponding state agencies must approve any replacement manufacturer before it can be approved as a commercial supplier. Such approval would require new testing, stability programs and compliance inspections. It may be difficult or impossible for Sunesis to identify and engage a reliable replacement manufacturer on acceptable terms in a timely manner, or at all. Sunesis expects to continue to depend on third-party CMOs for all its API and FDP needs for the foreseeable future.

Sunesis’s products require precise and high-quality manufacturing processes. In addition to process impurities, the failure of Sunesis’s CMOs to achieve and maintain high manufacturing standards in compliance with cGMP regulations could result in other manufacturing errors leading to patient injury or death, product recalls or withdrawals, delays or interruptions of production or failures in product testing or delivery. Although CMOs are subject to ongoing periodic unannounced inspection by the FDA, EMA or other corresponding state agencies to ensure strict compliance with cGMP and other applicable government regulations and corresponding foreign standards, any such performance failures on the part of a contract manufacturer could result in the delay or prevention of filing or approval of marketing applications for Sunesis’s products, cost overruns or other problems that could seriously harm Sunesis’s business. This would deprive Sunesis of potential product revenue and result in additional losses.

The stability of API and FDP is also a key risk, as Sunesis must demonstrate that products continue to meet product specifications over time. There can be no assurances that future lots will meet stability requirements and if they do not, development and commercialization of Sunesis’s products may be delayed.

The results of preclinical studies and clinical trials may not satisfy the requirements of the FDA, EMA or other regulatory agencies.

Prior to receiving approval to commercialize SNS-510 or future product candidates in Europe, the United States or in other territories, Sunesis must demonstrate with substantial evidence from well-controlled clinical trials, to the satisfaction of the FDA, EMA and other regulatory authorities, that such product candidates are safe and effective for their intended uses. The results from preclinical studies and clinical trials can be interpreted in different ways. Even if Sunesis believes preclinical or clinical data from preclinical studies and clinical trials are promising, such data may not be sufficient to support approval by the FDA, EMA and other regulatory authorities. Results in preclinical studies may not be predictive of results in human clinical trials and early stage human clinical trials may not be predictive of results in later, larger trials.

Sunesis’s product candidates, the methods used to deliver them or their dosage levels may cause undesirable side effects or have other properties that could delay or prevent their regulatory approval, limit the commercial profile of an approved label or result in significant negative consequences following any regulatory approval.

Undesirable side effects caused by Sunesis’s product candidates, their delivery methods or dosage levels could cause Sunesis or regulatory authorities to interrupt, delay or halt clinical trials and could result in a more restrictive label or the delay or denial of regulatory approval by the FDA or other comparable foreign regulatory authority. As a result of safety or toxicity issues that Sunesis may experience in its clinical trials, Sunesis may not receive approval to market any product candidates, which could prevent Sunesis from ever generating revenues or achieving profitability. Results of Sunesis’s trials could reveal an unacceptably high severity and incidence of side effects, or side effects outweighing the benefits of its product candidates. In such an event, Sunesis’s trials could be suspended or terminated, and the FDA or comparable foreign regulatory authorities could order Sunesis to cease further development of or deny approval of its product candidates for any or all targeted indications. The drug-related side effects could affect patient recruitment or the ability of enrolled subjects to complete the trial or result in potential product liability claims.

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Additionally, if any of Sunesis’s product candidates receives regulatory approval, and Sunesis or others later identify undesirable side effects caused by such product, a number of potentially significant negative consequences could result, including that:

Any of these events could diminish the usage or otherwise limit the commercial success of Sunesis’s product candidates and prevent Sunesis from achieving or maintaining market acceptance of the affected product candidate, if approved by applicable regulatory authorities.

Sunesis relies on third parties to conduct its clinical trials. If these third parties do not successfully carry out their contractual duties or fail to meet expected deadlines, Sunesis may be unable to obtain regulatory approval for, or commercialize, its product candidates.

Sunesis relies on third parties, such as CROs, medical institutions, clinical investigators and contract laboratories, to conduct its planned and existing clinical trials for its product candidates. If the third parties conducting Sunesis’s clinical trials do not perform their contractual duties or obligations, do not meet expected deadlines or need to be replaced, or if the quality or accuracy of the clinical data they obtain is compromised due to the failure to adhere to Sunesis’s clinical trial protocols or for any other reason, Sunesis may need to enter into new arrangements with alternative third parties and its clinical trials may be extended, delayed or terminated or may need to be repeated, and Sunesis may not be able to obtain regulatory approval for or commercialize the product candidate being tested in such trials.

Sunesis may expand its development capabilities in the future, and any difficulties hiring or retaining key personnel or managing this growth could disrupt its operations.

Sunesis is highly dependent on the principal members of its development staff. Sunesis may expand its research and development capabilities in the future by increasing expenditures in these areas, hiring additional employees and potentially expanding the scope of its current operations. Future growth will require Sunesis to continue to implement and improve Sunesis’s managerial, operational and financial systems and continue to retain, recruit and train additional qualified personnel, which may impose a strain on Sunesis’s administrative and operational infrastructure. The competition for qualified personnel in the biopharmaceutical field is intense. Sunesis is highly dependent on its continued ability to retain, attract and motivate highly qualified management and specialized personnel required for clinical development. Due to its limited resources, Sunesis may not be able to effectively manage any expansion of its operations or recruit and train additional qualified personnel. If Sunesis is unable to retain key personnel or manage its growth effectively, Sunesis may not be able to implement its business plan.

If Sunesis is sued for infringing intellectual property rights of third parties, litigation will be costly and time consuming and could prevent Sunesis from developing, commercializing, or licensing SNS-510, vecabrutinib, or other product candidates.

Sunesis’s commercial success depends on not infringing the patents and other proprietary rights of third parties and not breaching any collaboration or other agreements Sunesis has entered into with regard to its technologies and product candidates. If a third party asserts that Sunesis, Sunesis’s licensors, collaboration partners, or any employees thereof have misappropriated their intellectual property, or otherwise claim that Sunesis, Sunesis’s licensors, or collaboration partners are using technology claimed in issued and unexpired patents, or other proprietary rights, owned or controlled by the third party, even if the technology is regarded as Sunesis’s own intellectual property, Sunesis may need to obtain a license, enter into litigation to challenge the validity or enforceability of the patents or other rights or incur the risk of litigation in the event that a third party asserts that Sunesis infringes its patents or have misappropriated other rights.

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If a third party asserts that Sunesis infringes its patents or other proprietary rights, Sunesis could face a number of challenges that could seriously harm its competitive position, including:

If Sunesis’s competitors develop and market products that are more effective, safer or more popular than SNS-510 or other product candidates, or obtain marketing approval sooner than Sunesis’s, Sunesis’s commercial opportunities will be negatively impacted.

The life sciences industry is highly competitive, and Sunesis faces significant competition from many pharmaceutical, biopharmaceutical and biotechnology companies that are researching, developing and marketing products designed to address the treatment of cancer. Many of Sunesis’s competitors have significantly greater financial, manufacturing, marketing and drug development resources than Sunesis does. Large pharmaceutical companies in particular have extensive experience in the clinical testing of, obtaining regulatory approvals for, and marketing drugs.

Sunesis expects competition during the development and commercialization of all of its products in all of their potential future indications. Competition is likely to increase as additional products are developed and approved in various patient populations. If Sunesis’s competitors market products that are more effective, safer, and/or less expensive than Sunesis’s future products, if any, or that reach the market sooner Sunesis may not achieve commercial success or substantial market penetration. In addition, the biopharmaceutical industry is characterized by rapid change. Products developed by Sunesis’s competitors may render any of Sunesis’s future product candidates obsolete.

Sunesis’s proprietary rights may not adequately protect SNS-510, vecabrutinib, or future product candidates, if any.

Sunesis uses patents, trade secrets, trademarks, service marks, and marketing exclusivity administered by regulatory authorities to protect Sunesis’s products from generic copies of its products. Sunesis’s ability to build and maintain its proprietary position for any future drug candidates will depend on its success in obtaining effective patent claims and enforcing granted claims. The patent positions of biopharmaceutical companies like Sunesis’s are generally uncertain and involve complex legal and factual questions for which some important legal principles remain unresolved. No consistent policy regarding the breadth of patent claims has emerged to date in the United States. The patent situation outside the United States is even more uncertain. Sunesis does not know whether any of its patent applications or those patent applications that Sunesis licenses will result in the issuance of any patents. Even if patents are issued, they may not be sufficient to protect SNS-510, vecabrutinib, or other product candidates. The patents Sunesis owns or licenses and those that may be issued in the future may be opposed, challenged, invalidated or circumvented, and the rights granted under any issued patents may not provide Sunesis with proprietary protection or competitive advantages. Sunesis applies for patents covering both its technologies and product candidates, as it deems appropriate. However, Sunesis may fail to apply for patents on important technologies or product candidates in a timely fashion, throughout the world, or at all. Sunesis’s existing patents and any future patents Sunesis obtains may not be sufficiently broad, valid, enforceable, or extend globally in order to prevent others from practicing Sunesis’s technologies or from developing competing products and technologies. Further, obtaining and maintaining patent protection relies on compliance with various procedural requirements imposed by governmental patent agencies, including, for example, mandatory document submissions and fee payments. Failure to comply with these requirements may reduce or eliminate opportunities for, or rights to, patent protection. In addition, Sunesis generally does not exclusively control the patent prosecution of subject matter that Sunesis licenses to or from others. Accordingly, in such cases Sunesis is unable to exercise the same degree of control over this intellectual property as Sunesis would over its own. Similarly, Sunesis does not always exclusively control patent prosecution due to contractual and other legal obligations to its licensors and collaborations partners. Moreover, the patent positions of biopharmaceutical companies are highly uncertain and involve complex legal and factual questions for which important legal principles remain unresolved. As a result, the scope, validity and enforceability of patents in addition to the related cost, can vary from country to country, and can change depending on changes in national and international law, and as such, cannot be predicted with certainty. In addition, Sunesis does not know whether:

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Sunesis may need to commence or defend administrative proceedings or litigation to enforce or to determine the scope and validity of any patents issued to Sunesis or to determine the scope and validity of third-party proprietary rights. Litigation would result in substantial costs, even if the eventual outcome is favorable to Sunesis. An adverse outcome in a proceeding or litigation affecting proprietary rights Sunesis owns or has licensed could present significant risk of competition for drug candidates that Sunesis markets or seeks to develop. Any adverse outcome in a proceeding or litigation affecting third party proprietary rights could subject Sunesis to significant liabilities to third parties and could require Sunesis to seek licenses of the disputed rights from third parties or to cease using the technology if such licenses are unavailable.

There can be no assurance that the trademarks or service marks Sunesis uses or registers will protect its company name or any products or technologies that Sunesis develops and commercializes, that its trademarks, service marks, or trademark registrations will be enforceable against third parties, or that its trademarks and service marks will not interfere with or infringe trademark rights of third parties. Sunesis may need to commence litigation to enforce its trademarks and service marks or to determine the scope and validity of its or a third party’s trademark rights. Litigation would result in substantial costs, even if the eventual outcome is favorable to Sunesis. An adverse outcome in litigation could subject Sunesis to significant liabilities to third parties and require Sunesis to seek licenses of the disputed rights from third parties or to cease using the trademarks or service marks if such licenses are unavailable.

Sunesis also relies on trade secrets to protect some of its technology, especially where Sunesis does not believe patent protection is appropriate or obtainable. However, trade secrets are difficult to maintain and enforce. While Sunesis uses reasonable efforts to protect its trade secrets, Sunesis’s or Sunesis’s collaboration partners’ employees, consultants, contractors or scientific and other advisors, or those of Sunesis’s licensors or collaborators, may unintentionally or willfully disclose Sunesis’s proprietary information to competitors. Enforcement of claims that a third party has illegally obtained and is using trade secrets is expensive, time consuming and uncertain. In addition, foreign courts are sometimes less willing than U.S. courts to protect trade secrets. If Sunesis’s competitors independently develop equivalent knowledge, methods and know-how, Sunesis would not be able to assert its trade secret protection against them and Sunesis’s business could be harmed.

There can be no assurance that the confidentiality and other agreements Sunesis puts in place with employees, consultants, and partners will provide meaningful protection, that these agreements will not be breached, that Sunesis will have an adequate remedy for any such breach, or that Sunesis’s trade secrets will not otherwise become known or independently developed by a third party.

Sunesis does not know whether the patent term for any drug candidate or product will offer protection for an adequate or profitable amount of time. Sunesis does not know whether patent term extensions and data exclusivity periods will be available in the future for any or all of the patent rights Sunesis owns or has licensed. While it is possible that patent term restoration and/or supplemental patent certificates would be available for some of the patents Sunesis owns or controls through licenses, Sunesis cannot guarantee that such additional protection will be obtained, and the expiration dates described here do not include such term restoration. However, patent expiration dates described here for U.S. patents may reflect patent term adjustments by the United States Patent and Trademark Office or terminal disclaimers over related patents or patent applications. Sunesis’s obligation to pay royalties to licensors may extend beyond the patent expiration, which would further erode the profitability of Sunesis’s products.

Intellectual property rights may not address all potential threats to Sunesis’s competitive position for at least the reasons described above and below.

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Sunesis may not realize the potential benefits of its licensing arrangements for products such as vosaroxin and DAY101 (formerly TAK-580) and may not receive any future milestones or royalty payments.

There can be no assurance that products Sunesis out-licenses, such as vosaroxin to Denovo and DAY101 (formerly TAK-580) to DOT-1, will be successfully developed and commercialized. The product(s) may fail in development, or Sunesis’s partner(s) may elect to discontinue development and/or terminate their agreement(s) with Sunesis. In this case, Sunesis may also incur some costs to wind down Sunesis’s activities related to the product in question. Completing development of the product could require significant resources. If Sunesis cannot find another partner and do not undertake development on its own, there will be no possibility of any future upside from the product.

Sunesis may fail to make timely milestone or royalty payments under its agreements, triggering remedies that would be adverse to Sunesis.

Under Sunesis’s license agreements Sunesis has certain milestone and royalty obligations, such as the remaining development milestones payable for Sunesis’s development of PDK1 and on future sales of PDK1, when and if approved and commercialized, to Takeda Oncology. As another example, Sunesis is required to pay RPI Finance Trust (“RPI”), an entity related to Royalty Pharma, a specified percentage of any consideration Sunesis receives for vosaroxin. If Sunesis does not make timely payments, its partners may seek remedies.

Any future workforce and expense reductions may have an adverse impact on Sunesis’s internal programs, its ability to hire and retain key personnel and may be distracting to management.

In July 2020, Sunesis announced a reduction in workforce of approximately 30% of its head count to focus on development of Sunesis’s first-in-class PDK1 inhibitor SNS-510. On December 18, 2020, due to the entry into the Merger Agreement, Sunesis reduced its workforce by approximately 40% to preserve cash resources while completing the proposed Merger. Depending on Sunesis’s need for additional funding and expense control, Sunesis may be required to implement further workforce and expense reductions in the future. Further workforce and expense reductions may not result in efficiencies and anticipated savings and could result in reduced progress on Sunesis’s internal programs. In addition, employees, whether or not directly affected by a reduction, may seek future employment with Sunesis’s business partners or competitors. Although Sunesis’s employees are required to sign a confidentiality agreement at the time of hire, the confidentiality of certain proprietary information and knowledge may not be maintained in the course of any such future employment. Further, Sunesis believes that its future success will depend in large part upon its ability to attract and retain highly skilled personnel. Sunesis may have difficulty retaining and attracting such personnel as a result of a perceived risk of future workforce and expense reductions. In addition, the implementation of expense reduction programs may result in the diversion of efforts of Sunesis’s executive management team and other key employees, which could adversely affect its business.

Sunesis depends on various consultants and advisors for the success and continuation of its development efforts.

Sunesis works extensively with various consultants and advisors, who provide advice and/or services in various business and development functions, including clinical development, operations and strategy, clinical and nonclinical pharmacology, regulatory matters, biostatistics, legal and finance. The potential success of Sunesis’s drug development programs depends, in part, on continued collaborations with certain of these consultants and advisors. Sunesis’s consultants and advisors are not its employees and may have commitments and obligations to other entities that may limit their availability to Sunesis. Sunesis does not know if it will be able to maintain such relationships or that such consultants and advisors will not enter into other arrangements with competitors, any of which could have a detrimental impact on Sunesis’s development objectives and Sunesis’s business.

If conflicts of interest, or a failure or dispute of reporting or diligence efforts arise between Sunesis’s current or future licensees or collaboration partners, if any, and Sunesis, any of them may act in their self-interest, which may be adverse to Sunesis’s interests.

If a conflict of interest arises between Sunesis and one or more of its current or potential future licensees or collaboration partners, if any, they may act in their own self-interest or otherwise in a way that is not in the interest of Sunesis or its stockholders. Biogen, Takeda Oncology, Denovo, DOT-1, or potential future licensees or collaboration partners, if any, are conducting or may conduct product development efforts within the disease area that is the subject of a license or collaboration with Sunesis. In current or potential future licenses or collaborations, if any, Sunesis has agreed or may agree not to conduct, independently or with any third party, any research that is competitive with the research conducted under Sunesis’s licenses or collaborations. Sunesis’s licensees or collaboration partners, however, may develop, either alone or with others, products in related fields that are competitive with the

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product candidates that are the subject of these licenses or collaborations. Competing products, either developed by Sunesis’s licensees or collaboration partners or to which Sunesis’s licensees or collaboration partners have rights, may result in their withdrawal of support for a product candidate covered by the license or collaboration agreement.

If one or more of Sunesis’s current or potential future licensees or collaboration partners, if any, were to breach or terminate their license or collaboration agreements with Sunesis or otherwise fail to perform their obligations thereunder in a timely manner, the preclinical or clinical development or commercialization of the affected product candidates could be delayed or terminated. Sunesis does not know whether Sunesis’s licensees or collaboration partners will pursue alternative technologies or develop alternative product candidates, either on their own or in collaboration with others, including Sunesis’s competitors, as a means for developing treatments for the diseases targeted by licenses or collaboration agreements with Sunesis.

Sunesis and its current collaboration partners have certain reporting and diligence obligations to each other, and failure to report, or disagreement over the impact of information reported, or a lack of diligent efforts, or dispute of the impact of the efforts, may be adverse to Sunesis’s interests, the development of the product candidates and could lead to an ultimate withdrawal or dispute of the rights to a product candidate covered by the license or collaboration agreement.

Risks Related to Our Industry

The regulatory approval process is expensive, time consuming and uncertain and may prevent Sunesis from obtaining approval for the commercialization of its product candidates.

The research, testing, manufacturing, selling and marketing of product candidates are subject to extensive regulation by the FDA and other regulatory authorities in the United States and other countries, and regulations differ from country to country. Neither Sunesis nor its present or potential future collaboration or licensing partners, if any, are permitted to market Sunesis’s product candidates in the United States or Europe until Sunesis receives approval of a marketing authorization application (“MAA”) or New Drug Application (“NDA”) for these respective territories, or in any other country without the equivalent marketing approval from such country. In addition, failure to comply with FDA, EMA, and other applicable U.S. and foreign regulatory requirements may subject Sunesis to administrative or judicially imposed sanctions, including warning letters, civil and criminal penalties, injunctions, product seizure or detention, product recalls, total or partial suspension of production, and refusal to approve pending MAAs, NDAs, supplements to approved MAAs, NDAs or their equivalents in other territories.

Regulatory approval of an MAA or NDA or their equivalent in other territories is not guaranteed, and the approval process is expensive, uncertain and may take several years. Furthermore, the development process for oncology products may take longer than in other therapeutic areas. Regulatory authorities have substantial discretion in the drug approval process. Despite the time and expense exerted, failure can occur at any stage, and Sunesis could encounter problems that cause Sunesis to abandon clinical trials or to repeat or perform additional preclinical studies and clinical trials. The number of preclinical studies and clinical trials that will be required for marketing approval varies depending on the drug candidate, the disease or condition that the drug candidate is designed to address, and the regulations applicable to any particular drug candidate.

The FDA, EMA or other foreign regulatory authority can delay, limit or deny approval of a drug candidate for many reasons, including:

Sunesis may be subject to costly claims related to its clinical trials and may not be able to obtain adequate insurance.

Because Sunesis conducts the vecabrutinib clinical trials in humans, Sunesis faces the risk that the use of vecabrutinib will result in adverse side effects. Sunesis cannot predict the possible harms or side effects that may result from its clinical trials. Although Sunesis has clinical trial liability insurance, Sunesis’s insurance may be insufficient to cover any such events. Sunesis does not know whether it will be able to continue to obtain clinical trial coverage on acceptable terms, or at all. Sunesis may not have sufficient resources to pay for any liabilities resulting from a claim excluded from, or beyond the limit of, Sunesis’s insurance coverage. There is also a risk that third parties that Sunesis has agreed to indemnify could incur liability. Any litigation arising from Sunesis’s clinical trials, even if Sunesis was ultimately successful, would consume substantial amounts of Sunesis’s financial and managerial resources and may create adverse publicity.

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Even if Sunesis receives regulatory approval to sell SNS-510 or other product candidates, the market may not be receptive.

Even if one of Sunesis’s product candidates obtains regulatory approval, it may not gain market acceptance among physicians, patients, healthcare payors and/or the medical community. Sunesis believes that the degree of market acceptance will depend on a number of factors, including:

If SNS-510 or other product candidates fail to achieve market acceptance, due to unacceptable side effects or any other reasons, Sunesis may not be able to generate significant revenue or to achieve or sustain profitability.

Even if Sunesis receives regulatory approval for SNS-510 or any other future product candidate, Sunesis will be subject to ongoing FDA, EMA and other regulatory obligations and continued regulatory review, which may result in significant additional expense and limit its ability to commercialize SNS-510 or any other future product candidate.

Any regulatory approvals that Sunesis or its potential future collaboration partners receive for SNS-510 or its future product candidates, if any, may also be subject to limitations on the indicated uses for which the product may be marketed or contain requirements for potentially costly post-marketing trials. In addition, even if approved, the manufacturing, labeling, packaging, adverse event reporting, storage, advertising, promotion and recordkeeping for any product will be subject to extensive and ongoing regulatory requirements. The subsequent discovery of previously unknown problems with a product, including adverse events of unanticipated severity or frequency, may result in restrictions on the marketing of the product, and could include withdrawal of the product from the market.

The FDA and other agencies, including the Department of Justice (“DOJ”), closely regulate and monitor the post-approval marketing and promotion of products to ensure that they are marketed and distributed only for the approved indications and in accordance with the provisions of the approved labeling. The FDA and DOJ impose stringent restrictions on manufacturers’ communications regarding off-label use and if Sunesis does not market its products for their approved indications, Sunesis may be subject to enforcement action for off-label marketing. Violations of the Federal Food, Drug, and Cosmetic Act and other statutes, including the False Claims Act (the “FCA”), relating to the promotion and advertising of prescription drugs may lead to investigations and enforcement actions alleging violations of federal and state health care fraud and abuse laws and state consumer protection laws.

Regulatory policies may change and additional government regulations may be enacted that could prevent or delay regulatory approval of Sunesis’s product candidates. Sunesis cannot predict the likelihood, nature or extent of government regulation that may arise from future legislation or administrative action, either in the United States, Europe or other territories. If Sunesis is not able to maintain regulatory compliance, Sunesis might not be permitted to market its future products and Sunesis may not achieve or sustain profitability. Other penalties for failing to comply with regulatory requirements include restrictions on such products, manufacturers or manufacturing processes; restrictions on the labeling or marketing of a product; restrictions on distribution or use of a product; requirements to conduct post-marketing studies or clinical trials; warning letters or untitled letters; withdrawal of the products from the market; refusal to approve pending applications or supplements to approved applications that Sunesis submits; recall of products; damage to relationships with any potential collaborators; unfavorable press coverage and damage to Sunesis’s reputation; fines, restitution or disgorgement of profits or revenues; suspension or withdrawal of marketing approvals; refusal to permit the import or export of Sunesis’s products; product seizure; injunctions or the imposition of civil or criminal penalties; and litigation involving patients using Sunesis’s products. Additionally, failure to comply with the European Union’s requirements regarding the protection of personal information also can lead to significant penalties and sanctions.

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The coverage and reimbursement status of newly approved drugs is uncertain and may be impacted by current and future legislation, and failure to obtain adequate coverage and reimbursement could limit Sunesis’s ability to market its product candidates and decrease its ability to generate revenue.

There is significant uncertainty related to the third-party coverage and reimbursement of newly approved drugs both nationally and internationally. The commercial success of Sunesis’s future products, if any, in both domestic and international markets depends on whether third-party coverage and reimbursement is available for the ordering of Sunesis’s future products by the medical profession for use by their patients. Medicare, Medicaid, health maintenance organizations and other third-party payors are increasingly attempting to manage healthcare costs by limiting both coverage and the level of reimbursement of new drugs and, as a result, they may not cover or provide adequate payment for Sunesis’s future products. These payors may not view Sunesis’s future products as cost-effective, and reimbursement may not be available to consumers or may not be sufficient to allow Sunesis’s future products to be marketed on a competitive basis.

Likewise, in the United States and some foreign jurisdictions, there have been a number of legislative or regulatory efforts to control or reduce healthcare costs or reform government healthcare programs that could result in lower prices or rejection of Sunesis’s future products. Such efforts have resulted in several recent United States congressional inquiries and proposed and enacted federal and state legislation 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 products.

For example, in response to the COVID-19 pandemic, the CARES Act was signed into law in March 2020. The CARES Act is aimed at providing emergency assistance and health care for individuals, families and businesses affected by the COVID-19 pandemic and generally supporting the U.S. economy. Generally, there has been increasing legislative and enforcement interest in the U.S. with respect to drug pricing, including specialty drug pricing practices, in light of the rising cost of prescription drugs and biologics. Specifically, there have been U.S. Congressional inquiries and federal and state legislative activity designed to, among other things, bring more transparency to drug pricing, review the relationship between pricing and manufacturer patient programs, reduce the price of drugs under Medicare, and reform government program reimbursement methodologies for drugs and biologics. While a number of reform measures may require additional authorization to become effective, Congress and the Trump Administration have each indicated that they will continue to seek new legislative and/or administrative measures to control drug costs. Sunesis expects that additional state and federal healthcare reform measures may be adopted in the future, any of which could limit the amounts that federal and state governments will pay for healthcare products and services. The evolving effects of the COVID-19 pandemic may introduce temporary or permanent healthcare reform measures, which could have negative financial implications on Sunesis’s business. Changes in coverage and reimbursement policies or healthcare cost containment initiatives that may limit or restrict reimbursement for Sunesis’s future products may reduce any future product revenue.

Additionally, in March 2010, the Patient Protection and Affordable Care Act, as amended by the Health Care and Education Reconciliation Act of 2010 (collectively, the “ACA”), was enacted, which made a number of substantial changes in the way healthcare is financed by both governmental and private insurers. In the years since its enactment, there have been, and continue to be, significant developments in, and continued legislative activity around, attempts to repeal or repeal and replace the ACA. While Congress has not passed comprehensive repeal legislation, it has enacted laws that modify certain provisions of the ACA such as removing penalties, starting January 1, 2019, for not complying with the ACA’s individual mandate to carry health insurance and delaying the implementation of certain ACA-mandated fees. In addition, the 2020 federal spending package permanently eliminated, effective January 1, 2020, the ACA-mandated “Cadillac” tax on high-cost employer-sponsored health coverage and medical device tax 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 TCJA. Additionally, on December 18, 2019, the U.S. Court of Appeals for the 5th Circuit upheld the District Court ruling 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. The Supreme Court of the United States granted certiorari on March 2, 2020, and heard oral arguments on the case on November 10, 2020, and the case is expected to be decided sometime in 2021. It is unclear how this decision, future decisions, subsequent appeals, and other efforts to repeal and replace the ACA will impact the ACA and Sunesis’s business and operations.

The implementation of cost containment measures or other healthcare reforms may prevent Sunesis from being able to generate revenue, attain profitability, or commercialize its products.

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Sunesis’s relationships with healthcare providers, clinical investigators, and third-party payors will be subject to applicable anti-kickback, fraud and abuse and other healthcare laws and regulations, which, in the event of a violation, could expose Sunesis to criminal sanctions, civil penalties, contractual damages, reputational harm and diminished profits and future earnings.

Healthcare providers, clinical investigators, and third-party payors will play a primary role in the recommendation and prescription of any drug candidates for which Sunesis obtains marketing approval. Sunesis’s current and future arrangements with healthcare providers, clinical investigators and third-party payors may expose Sunesis to broadly applicable fraud and abuse and other healthcare laws and regulations that may constrain the business or financial arrangements and relationships through which Sunesis markets, sells and distributes any products for which Sunesis obtains marketing approval. Restrictions under applicable state, federal and foreign healthcare laws and regulations include the following:

Efforts to ensure that Sunesis’s business arrangements with third parties will comply with applicable healthcare laws and regulations will involve substantial costs. It is possible that governmental authorities will conclude that Sunesis’s 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 Sunesis’s operations are found to be in violation of any of the health regulatory laws described above or any other laws that apply to Sunesis, Sunesis may be subject to a wide range of sanctions and penalties, including potentially significant criminal, and civil and/or administrative penalties, damages, fines, disgorgement, imprisonment, exclusion from participation in

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government healthcare programs, integrity obligations, contractual damages, reputational harm, administrative burdens, diminished profits and future earnings, and the curtailment or restructuring of Sunesis’s operations, any of which could adversely affect Sunesis’s ability to operate its business and its results of operations. Sunesis is unable to predict whether Sunesis would be subject to actions under these laws or the impact of such actions. However, the cost of defending any such claims, as well as any sanctions imposed, could adversely affect Sunesis’s financial performance and disrupt Sunesis’s business operations.

Sunesis may incur significant costs complying with environmental laws and regulations, and failure to comply with these laws and regulations could expose Sunesis to significant liabilities.

Sunesis, through third-party contractors, use hazardous chemicals and radioactive and biological materials in its business and are subject to a variety of federal, state, regional and local laws and regulations governing the use, generation, manufacture, storage, handling and disposal of these materials. Although Sunesis believes its safety procedures for handling and disposing of these materials and waste products comply with these laws and regulations, Sunesis cannot eliminate the risk of accidental injury or contamination from the use, storage, handling or disposal of hazardous materials. In the event of contamination or injury, Sunesis could be held liable for any resulting damages, and any liability could significantly exceed Sunesis’s insurance coverage, which is limited for pollution cleanup and contamination.

General Risk Factors

The price of our common stock may continue to be volatile, and the value of an investment in its common stock may decline.

In the year ended December 31, 2020, our common stock traded as low as $1.12 and as high as $11.30, after giving retroactive effect to the one-for-ten reverse split of shares of Sunesis’s capital stock, effected on September 2, 2020. Factors that could cause continued volatility in the market price of our common stock include, but are not limited to:

Moreover, on March 12, 2020, the WHO declared COVID-19 to be a pandemic, and the COVID-19 pandemic has resulted in significant financial market volatility and uncertainty in recent months. A continuation or worsening of the levels of market disruption and volatility seen in the recent past could have an adverse effect on Sunesis’s ability to access capital, on Sunesis’s business, results of operations and financial condition, and on the market price of Sunesis’s common stock.

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Sunesis’s failure to meet the continued listing requirements of The Nasdaq Stock Market LLC could result in a delisting of its common stock.

Our common stock is listed on The Nasdaq Stock Market LLC, which imposes, among other requirements a minimum bid requirement. our common stock traded for less than $1.00 for 30 consecutive trading days, and Sunesis received notice of this from the Listing Qualifications Staff of The Nasdaq Stock Market LLC on July 9, 2019. After effecting the Reverse Stock Split on September 2, 2020, Sunesis received a letter from the Nasdaq Listing Qualifications Department notifying Sunesis that it had regained compliance with the Nasdaq minimum bid price requirement and the matter is now closed. However, if the closing bid price of our common stock was to fall below $1.00 per share for 30 consecutive trading days again in the future, or Sunesis does not meet other listing requirements, Sunesis would fail to be in compliance with Nasdaq’s listing standards. There can be no assurance that Sunesis will continue to meet the minimum bid price requirement, or any other requirement in the future. If Sunesis fails to meet the minimum bid price requirement, or other applicable Nasdaq listing requirements, including maintaining minimum levels of stockholders’ equity or market values of Sunesis’s common stock, its common stock could be delisted. If our common stock were to be delisted, the liquidity of its common stock would be adversely affected, and the market price of its common stock could decrease.

Sunesis’s facilities are located near known earthquake fault zones, and the occurrence of an earthquake or other catastrophic disaster, or interruption by man-made problems such as network security breaches, viruses or terrorism, could cause damage to Sunesis’s facilities and equipment, which could require Sunesis to cease or curtail operations.

Sunesis’s facilities are located in the San Francisco Bay Area near known earthquake fault zones and are vulnerable to significant damage from earthquakes. Sunesis is also vulnerable to damage from other types of disasters, including fires, floods, power loss, communications failures and other catastrophic events, such as the ongoing Coronavirus epidemic. Despite the implementation of network security measures, Sunesis’s networks also may be vulnerable to computer viruses, break-ins and similar disruptions. Sunesis relies on information technology systems to operate its business and to communicate among its workforce and with third parties. If any disruption were to occur, whether caused by a natural disaster or by manmade problems, Sunesis’s ability to operate its business at its facilities may be seriously or completely impaired and Sunesis’s data could be lost or destroyed.

Sunesis’s systems are potentially vulnerable to data security breaches, whether by employees or others, that may expose sensitive data to unauthorized persons. If Sunesis is unable to prevent such data security breaches or implement satisfactory remedial measures, Sunesis’s operations could be disrupted, and Sunesis may suffer loss of reputation, financial loss and other regulatory penalties because of lost or misappropriated information. In addition, these breaches and other inappropriate access can be difficult to detect, and any delay in identifying them may lead to increased harm of the type described above. U.S. and international authorities have been warning businesses of increased cybersecurity threats from actors seeking to exploit the COVID-19 pandemic. If Sunesis is unable to prevent potential data security breaches or privacy violations, Sunesis’s operations could be disrupted, and Sunesis may suffer loss of reputation, financial loss and other regulatory penalties because of lost or misappropriated information, including sensitive patient data.

Moreover, 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, trade secrets or other intellectual property. While Sunesis has implemented security measures to protect its data security and information technology systems, such measures may not prevent such events. Such disruptions and breaches of security could have a material adverse effect on Sunesis’s business, financial condition and results of operations.

Compliance with changing regulation of corporate governance and public disclosure may result in additional expenses.

Changing laws, regulations and standards relating to corporate governance and public disclosure may create uncertainty regarding compliance matters. New or changed laws, regulations and standards are subject to varying interpretations in many cases. As a result, their application in practice may evolve over time. Sunesis is committed to maintaining high standards of corporate governance and public disclosure. Complying with evolving interpretations of new or changed legal requirements may cause Sunesis to incur higher costs as Sunesis revises current practices, policies and procedures, and may divert management time and attention from potential revenue-generating activities to compliance matters. If Sunesis’s efforts to comply with new or changed laws, regulations and standards differ from the activities intended by regulatory or governing bodies due to ambiguities related to practice, Sunesis’s reputation may also be harmed. Further, Sunesis’s board members and executive officers could face an increased risk of personal liability in connection with the performance of their duties. As a result, Sunesis may have difficulty attracting and retaining qualified board members and executive officers, which could harm its business. Sunesis’s Directors and Officers insurance provides certain coverage to its board members and executive officers, but the cost of coverage may be prohibitively expensive or not provide enough coverage.

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Sunesis’s ability to use NOL carryforwards to offset future taxable income, and its ability to use tax credit carryforwards, may be subject to certain limitations.

Sunesis’s ability to use its federal and state NOL carryforwards to offset potential future taxable income and related income taxes that would otherwise be due is dependent upon its generation of future taxable income, and Sunesis cannot predict with certainty when, or whether, Sunesis will generate sufficient taxable income to use all of its NOL carryforwards.

As of December 31, 2020, Sunesis reported U.S. federal and state NOL carryforwards of approximately $475.8 million and $335.0 million, respectively. Sunesis’s federal NOL carryforwards generated prior to 2018 will continue to be governed by the NOL tax rules as they existed prior to the adoption of the U.S. federal tax legislation commonly referred to as the Tax Cuts and Jobs Act (the “Tax Act”), which means that generally they will expire 20 years after they were generated if not used prior thereto. $414.6 million of Sunesis’s $475.8 million federal NOL carryforwards are subject to the 20 years expirations and a portion will continue to expire each year until 2037. Many states have similar laws, and Sunesis’s state NOL carryforwards will begin to expire in 2028. Accordingly, these federal and state NOL carryforwards could expire unused and be unavailable to offset future income tax liabilities. Under the Tax Act as modified by the Coronavirus Aid, Relief, and Economic Security Act (the “CARES Act”) signed into law on March 27, 2020, federal NOLs incurred in taxable years beginning after December 31, 2017 may be carried forward indefinitely, but the deductibility of such federal NOL carryforwards in tax years beginning after December 31, 2020 is limited to 80% of current year taxable income. It is uncertain if and to what extent various states will conform to the Tax Act or the CARES Act.

In addition, under Section 382 of the Code, Sunesis’s ability to utilize these NOL carryforwards and other tax attributes, such as federal tax credits, in any taxable year may be limited if Sunesis has experienced an “ownership change.” Generally, a Section 382 ownership change occurs if one or more stockholders or groups of stockholders who owns at least 5% of a corporation’s stock increases its ownership by more than 50 percentage points over its lowest ownership percentage within a three-year testing period. Similar rules may apply under state tax laws. Any such material limitation or expiration of Sunesis’s NOL carryforwards may harm Sunesis’s future operating results by effectively increasing its future tax obligations.

Provisions of Sunesis’s charter documents or Delaware law could delay or prevent an acquisition of Sunesis, even if the acquisition would be beneficial to Sunesis’s stockholders, and could make it more difficult to change management.

Provisions of Sunesis’s amended and restated certificate of incorporation and amended and restated bylaws may discourage, delay or prevent a merger, acquisition or other change in control that stockholders might otherwise consider favorable, including transactions in which stockholders might otherwise receive a premium for their shares. In addition, these provisions may frustrate or prevent any attempt by Sunesis’s stockholders to replace or remove its current management by making it more difficult to replace or remove its board of directors. These provisions include:

In addition, Delaware law prohibits a publicly held Delaware corporation from engaging in a business combination with an interested stockholder, generally a person who, together with its affiliates, owns or within the last three years has owned 15% of Sunesis’s voting stock, for a period of three years after the date of the transaction in which the person became an interested stockholder, unless the business combination is approved in a prescribed manner. Accordingly, Delaware law may discourage, delay or prevent a change in control of Sunesis.

Provisions in Sunesis’s charter documents and provisions of Delaware law could limit the price that investors are willing to pay in the future for shares of Sunesis’s common stock.

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Sunesis has never paid dividends on its capital stock and Sunesis does not anticipate paying any cash dividends in the foreseeable future.

Sunesis has never declared or paid cash dividends on its capital stock. Sunesis does not anticipate paying any cash dividends on its capital stock in the foreseeable future. Sunesis currently intends to retain all available funds and any future earnings to fund the development and growth of its business. As a result, capital appreciation, if any, of our common stock will be Sunesis’s stockholders’ sole source of gain for the foreseeable future.

Sunesis is at risk of securities class action litigation.

In the past, securities class action litigation has often been brought against a company following a decline in the market price of its securities. This risk is especially relevant for Sunesis because biotechnology companies have experienced greater than average stock price volatility in recent years. These broad market fluctuations may adversely affect the trading price or liquidity of Sunesis’s common stock. In the past, when the market price of a stock has been volatile, holders of that stock have sometimes instituted securities class action litigation against the issuer. If any of Sunesis’s stockholders were to bring such a lawsuit against Sunesis, Sunesis could incur substantial costs defending the lawsuit and the attention of Sunesis’s management would be diverted from the operation of Sunesis’s business.

Future sales and issuances of our common stock or rights to purchase common stock, including pursuant to Sunesis’s equity incentive plans, could result in additional dilution of the percentage ownership of Sunesis’s stockholders and could cause its stock price to fall.

Sunesis expects that significant additional capital will be needed in the future to continue its planned operations. To raise capital, Sunesis may sell substantial amounts of common stock or securities convertible into or exchangeable for common stock in one or more transactions at prices and in a manner Sunesis determines from time to time. These future issuances of common stock or common stock-related securities, together with the exercise of outstanding options and any additional shares issued in connection with acquisitions or in-licenses, if any, may result in material dilution to Sunesis’s investors. Such sales may also result in material dilution to Sunesis’s existing stockholders, and new investors could gain rights, preferences and privileges senior to those of holders of Sunesis’s common stock.

Pursuant to Sunesis’s equity incentive plans, Sunesis’s compensation committee is authorized to grant equity-based incentive awards to its employees, non-employee directors and consultants. Future grants of RSUs, options and other equity awards and issuances of common stock under Sunesis’s equity incentive plans will result in dilution and may have an adverse effect on the market price of Sunesis’s common stock.

If securities or industry analysts do not publish research or publish inaccurate or unfavorable research about Sunesis’s business, Sunesis’s stock price and trading volume could decline.

The trading market for our common stock will depend in part on the research and reports that securities or industry analysts publish about Sunesis and its business. In the event securities or industry analysts who cover Sunesis downgrade its stock or publish unfavorable research about Sunesis or its business, Sunesis’s stock price would likely decline. If one or more of these analysts cease coverage of Sunesis or fail to publish reports on Sunesis regularly, demand for Sunesis’s stock could decrease, which might cause Sunesis’s stock price and trading volume to decline.

Sunesis’s Amended and Restated Bylaws provide that the Court of Chancery in the State of Delaware is the sole and exclusive forum for substantially all disputes between Sunesis and its stockholders, which could limit the stockholders’ ability to obtain a favorable judicial forum for disputes with Sunesis or its directors, officers or employees.

Sunesis’s Amended and Restated Bylaws, or the Bylaws, provide that, unless the Sunesis Board of Directors consents to an alternative forum, the Court of Chancery in the State of Delaware will be the sole and exclusive forum for: (i) any derivative action or proceeding brought on Sunesis’s behalf; (ii) any action asserting a breach of fiduciary duty; (iii) any action asserting a claim against Sunesis arising under the DGCL; (iv) any action regarding the Bylaws; (v) any action as to which the DGCL confers jurisdiction to the Court of Chancery of the State of Delaware; or (vi) any action asserting a claim against Sunesis that is governed by the internal affairs doctrine. The provisions do not apply to suits brought to enforce a duty or liability created by the Securities Act of 1933, as amended (the “Securities Act”), or the Securities Exchange Act of 1934, as amended. Sunesis believes this provision benefits Sunesis by providing increased consistency in the application of Delaware law by chancellors particularly experienced in resolving corporate disputes, efficient administration of cases on a more expedited schedule relative to other forums and protection against the burdens of multi-forum litigation. However, the provision may have the effect of discouraging lawsuits against Sunesis’s directors and officers.

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