ASMB US Equity☆

Item 1A. Risk Factors

You should carefully consider the following risk factors, together with all other information in this report, including our consolidated financial statements and notes thereto, and in our other filings with the SEC. If any of the following risks, or other risks not presently known to us or that we currently believe to not be material, develop into actual events, then our business, financial condition, results of operations or prospects could be materially adversely affected. If that happens, the market price of our common stock could decline, and stockholders may lose all or part of their investment.

Risks Related to Our Business

We have no approved products and depend on the future success of the product candidates in our research and development pipeline. We cannot be certain that we or our collaborators will be able to obtain regulatory approval for, or successfully commercialize, product candidates from our current pipeline or any other product candidates that we may subsequently identify, license or otherwise acquire.

We and our collaborators are not permitted to market or promote any products in the United States, Europe, China or other countries before we receive regulatory approval from the FDA or comparable foreign regulatory authorities, and we may never receive such regulatory approval for our current product candidates. We have not submitted a new drug application (NDA) to the FDA or comparable applications to other regulatory authorities and do not expect to be in a position to do so in the near future.

All of our product candidates are in clinical development or in varying stages of nonclinical development. Data supporting our drug discovery and nonclinical and clinical development programs are derived from laboratory studies, nonclinical studies and Phase 1 clinical studies. It may be years before the larger, pivotal studies necessary to support regulatory approval of our current product candidates are completed, if ever.

In addition to our current product pipeline, we may identify, license or otherwise acquire rights to other technologies or product candidates. Any such transactions would involve numerous risks, and we may be unsuccessful in entering into any such transactions or developing any such technologies or product candidates.

For these reasons, our drug discovery and development may not be successful, and we may be unable to continue clinical development of our product candidates and may not generate product approvals or product revenue, any of which could have a material adverse impact on our business, results of operations and financial condition.

We are not currently profitable and might never become profitable, and we will need additional financing to complete the development of any product candidates and fund our activities into the future.

We do not have any approved products, and we have a history of losses. We expect to continue to incur substantial operating and capital expenditures to advance our current product candidates through clinical development, continue research and discovery efforts to identify potential additional product candidates and seek regulatory approvals for our current and future product candidates. All operations and capital expenditures will be funded from cash on hand, securities offerings, debt financings and payments we may receive from out-licenses, collaborations or other strategic arrangements. Elevated worldwide inflation rates that began in mid-2021 and continue to persist may also exacerbate the substantial operating and capital expenditures that we face to advance our current and future product candidates.

There is no assurance that we will be successful in raising any necessary additional capital on terms that are acceptable to us, or at all, particularly due to the well-documented, ongoing sector-wide weakness in the biotech markets that began in early 2021. If we are unable to develop and commercialize any product candidates and generate sufficient revenue or raise capital, we could be forced to reduce staff, delay, scale back or discontinue product development and clinical studies, sacrifice attractive business opportunities, cease operations entirely and sell, or otherwise transfer, all or substantially all of our remaining assets, which would likely have a material adverse impact on our business, results of operations, financial condition and share price.

We expect our collaboration with Gilead to be a critical part of the development, manufacture and commercialization of our product candidates. If this collaboration is unsuccessful, our business could be adversely affected.

In October 2023, we entered into the Gilead Collaboration Agreement with Gilead, whereby Gilead exclusively licensed to us its HPI program and NNPI program, while retaining opt-in rights to these programs, and will have an option to take an exclusive license, on a program-by-program basis, to all of our other current and future pipeline

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programs during the collaboration term. In connection with the entry into the Gilead Collaboration Agreement, we and Gilead also entered into a common stock purchase agreement and an investor rights agreement. Our agreements and relationship with Gilead pose a number of risks, including, but not limited to, the following:

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Conflicts may arise between us and Gilead, such as conflicts regarding the indications to pursue or concerning the clinical data supporting an opt-in decision, the commercial potential of any optioned investigational products, the interpretation of financial provisions or the ownership of intellectual property developed during the collaboration. Any such conflicts could slow or prevent the development or commercialization of our investigational products.

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If the collaboration with Gilead does not result in the successful development and commercialization of products or if Gilead terminates the Gilead Collaboration Agreement with us, we may not receive any future research funding or milestone or royalty payments under the collaboration. If we do not receive the funding we expect under these agreements, our development of our investigational products could be delayed and we may need additional resources to develop our investigational products.

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We will be heavily dependent on Gilead for further development and commercialization of the investigational products from the programs that it opts into.

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We may not be successful in this collaboration due to various other factors, including our ability to demonstrate proof of concept in one or more clinical studies so that Gilead will exercise its option to these programs. In addition, even if we demonstrate clinical proof of concept of a candidate, Gilead may choose not to exercise its option.

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Gilead has the right to designate two directors for appointment to our board of directors pursuant to the terms of the investor rights agreement and owns approximately 19.9% of our outstanding common stock. Gilead also has the right to acquire additional shares from us, and in the open market, up to an amount resulting in Gilead owning a total of 35% of our outstanding common stock. As a result, Gilead may be able to exert significant influence over us.

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Gilead could independently develop, or develop with third parties, products that compete directly or indirectly with our investigational products if Gilead believes that competitive products are more likely to be successfully developed or can be commercialized under terms that are more economically attractive than ours.

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Because Gilead has an option to all of our current, and future, pipeline programs during the collaboration term, it may be difficult for us to enter into new collaborations.

Nonclinical and clinical studies required for our product candidates are expensive and time-consuming and may fail to demonstrate the level of safety and efficacy necessary for product approval.

Before we or any commercial partners can obtain FDA approval (or other foreign approvals) necessary to sell any of our product candidates, we must show that each potential product is safe and effective. To meet these requirements, we must conduct extensive nonclinical and sufficient, well-controlled clinical studies.

The results of laboratory and nonclinical studies may not be representative of disease behavior in a clinical setting and may not be predictive of the outcomes of our clinical studies. In addition, the results of early clinical studies of product candidates may not be predictive of the results of later-stage clinical studies.

Conducting nonclinical and clinical studies is a lengthy, time consuming and expensive process. The length of time varies substantially according to the type, complexity, novelty, and intended use of the product candidate, and often can be several years or more. In addition, failure or delays can occur at any time during the nonclinical and clinical study process, resulting in additional operating expenses or harm to our business.

The commencement and rate of completion of clinical studies might be delayed by many factors, including, for example:

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delays in reaching agreement with regulatory authorities on study design;

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delays in reaching agreement on acceptable terms with prospective CROs and clinical study sites;

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failure to demonstrate efficacy or the emergence of unforeseen safety issues;

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insufficient quantities of qualified materials under current good manufacturing practice (cGMP) for use in clinical studies due to manufacturing challenges, delays or interruptions in the supply chain;

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slower than expected rates of patient recruitment or failure to recruit a sufficient number of eligible patients, which may be due to a number of reasons, including the size of the patient population, the proximity of patients to clinical sites, the eligibility criteria for the study, the design of the clinical study, and other potential drug candidates being studied;

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delays in patients completing participation in a study or return for post-treatment follow-up for any reason, including, product side effects or disease progression;

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modification of clinical study protocols;

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delays, suspension, or termination of clinical studies by the institutional review board or ethics committee responsible for overseeing the study at a particular study site; and

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government or other regulatory agency delays or clinical holds requiring suspension or termination of our clinical studies due to safety, tolerability or other issues related to our product candidates.

The failure of nonclinical and clinical studies to demonstrate safety and effectiveness of a product candidate for the desired indications, whether conducted by us or by a CRO, would harm the development of that product candidate and potentially other product candidates. This failure could cause us to abandon a product candidate and could delay development of other product candidates. Any delay in, or failure of, our nonclinical studies or clinical studies could delay, or preclude, the filing of our NDAs and comparable applications with the FDA and foreign regulatory agencies, as applicable, and materially harm our business, prospects, financial condition and results of operations.

We rely on CROs to conduct some of our nonclinical and clinical studies due to our lack of suitable facilities and resources. In addition, parts of our business are reliant on CROs, vendors, suppliers and other service providers in locations outside of the United States, including China.

We do not have sufficient facilities or resources to conduct all our anticipated nonclinical and clinical studies internally. As a result, we contract with CROs to conduct a significant portion of the nonclinical and clinical studies required for regulatory approval for our product candidates. Our reliance on CROs reduces our control over these activities but does not relieve us of our responsibilities. For example, we are responsible for ensuring that each of our studies is conducted in accordance with the applicable protocol, legal and regulatory requirements and scientific standards, including, in the case of clinical studies, good clinical practices, even if the study is conducted by a CRO. In the event CROs fail to perform their duties in such a fashion or we are unable to retain or continue with CROs on acceptable terms, we may be unable to complete our clinical studies and may fail to obtain regulatory approval for our product candidates.

In addition, these CROs may also have relationships with other entities, some of which may be our competitors. CRO personnel are not our employees, and except for remedies available to us under our agreements with such third parties, we cannot control whether they devote sufficient time and resources to our clinical and nonclinical studies. If these CROs do not successfully carry out their contractual duties or obligations or meet expected deadlines, if they 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 our clinical protocols, regulatory requirements or for other reasons, our research, nonclinical or clinical studies may be extended, delayed or terminated and we may not be able to obtain, or may be delayed in obtaining, regulatory approvals for our product candidates, any of which could materially harm our business, prospects, financial condition and results of operations.

Furthermore, we are exposed to a number of risks related to our CROs, vendors, suppliers and other service providers that are located outside of the United States, many of which may be beyond our control. These risks include:

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business interruptions resulting from geopolitical actions such as the war between Russia and Ukraine, the Israel-Hamas war, as well as tariffs, other wars, acts of terrorism, natural disasters or outbreaks of disease;

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different regulatory requirements for drug approvals or increased scrutiny on CROs located in foreign countries, including China;

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different standards of care in various countries that could complicate the evaluation of our product candidates;

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different U.S. and foreign drug import and export rules;

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different reimbursement systems and different competitive drugs indicated to treat the indication for which our product candidates are being developed;

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reduced protection for intellectual property rights in certain countries;

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unexpected changes in tariffs, trade barriers and regulatory requirements;

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compliance with the United States Foreign Corrupt Practices Act (the FCPA) and other anti-corruption and anti-bribery laws;

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compliance with tax, employment, immigration and labor laws for employees living or traveling abroad;

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foreign taxes, including withholding of payroll taxes; and

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foreign currency fluctuations and compliance with foreign currency exchange rules, which could result in increased operating expenses and reduced revenues, and other obligations incident to doing business in another country.

Top-line or preliminary data may not accurately reflect the final results of a particular study.

We may publicly disclose top-line or preliminary data based on analysis of then-available efficacy, tolerability, PK and safety data, and the results and related findings and conclusions are subject to change following a more comprehensive review of the data related to the particular study. We also make assumptions, estimates, calculations and conclusions as part of our data analyses, and we may not have received or had the opportunity to fully and carefully evaluate all data prior to release. As a result, the top-line or preliminary results that we report may differ from final results of the same studies or different conclusions or considerations may qualify such results once additional data have been received and fully evaluated. Top-line data also remains subject to audit and verification procedures that may result in the final data differing materially from previously published preliminary data. As a result, top-line and preliminary data should be viewed with caution until the final data are available.

In addition to top-line or preliminary results, the information that we may publicly disclose regarding a particular nonclinical or clinical study is based on extensive information, and you or others may not agree with what we determine is the material or otherwise appropriate information to include in our disclosure. In addition, any information we determine not to disclose may ultimately be deemed significant with respect to future decisions, conclusions, views, activities or otherwise regarding a particular drug, drug candidate or our business. If the top-line or preliminary data that we report differ from final results, or if others, including regulatory authorities, disagree with, or do not accept, the data or conclusions reached, our ability to obtain approval for, and commercialize, our product candidates may be harmed or delayed, which could harm our business, financial condition, operating results or prospects.

We rely on third parties to formulate and manufacture our product candidates and products that we study in combination with our product candidates. Our use of third parties may increase the risk that we will not have sufficient quantities of our product candidates or other products on time or at an acceptable cost.

We rely on third-party manufacturers to supply the quantities of our investigational product candidates used in our clinical and nonclinical studies. If any product candidate we develop or acquire in the future receives FDA or other regulatory approval, we expect to continue our reliance on one or more third-party contractors to manufacture our products. If, for any reason, we are unable to rely on any third-party sources we have identified to manufacture our product candidates, we would need to identify and contract with additional or replacement third-party manufacturers to manufacture drug substance and drug product for nonclinical, clinical and commercial purposes. We may be unsuccessful in identifying additional or replacement third-party manufacturers, or in negotiating acceptable terms with any that we do identify. If we are unable to establish and maintain manufacturing capacity, the development and sales of our products and our financial performance may be materially and adversely affected.

We are exposed to the following risks with respect to the manufacture of our product candidates:

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We will need to identify manufacturers for commercial supply on acceptable terms, which we may be unable to do because the number of potential manufacturers is limited, and the FDA must evaluate and approve any new or replacement contractor.

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Any third-party manufacturers with whom we contract might be unable to formulate and manufacture our product candidates in the volume and quality required to meet our nonclinical, clinical and, if approved, commercial needs in a timely manner.

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Any third-party manufacturers with whom we contract might not perform as agreed or might not remain in the contract manufacturing business for the time required to supply our products.

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One or more of any third-party manufacturers with whom we contract could be foreign, which increases the risk of shipping delays and adds the risk of import restrictions.

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We do not have complete control over, and cannot ensure, any third-party manufacturers’ compliance with cGMP and other government regulations and corresponding foreign requirements, including periodic FDA and state regulatory inspections.

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We may be required to obtain intellectual property rights from third parties to manufacture our product candidates, and if any third-party manufacturer makes improvements in the manufacturing process for our product candidates, we may not own, or may have to share, the intellectual property rights to the innovation.

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We may be required to share our trade secrets and know-how with third parties, increasing risk of misappropriation or disclosure of our intellectual property by or to third parties.

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When contracting with third-party manufacturers, we might compete with other companies for access to these manufacturers’ facilities and might be subject to manufacturing delays if the manufacturers give other clients higher priority than we are given.

Each of these risks could delay our development efforts, nonclinical studies and clinical studies or the approval, if any, of our product candidates by the FDA or applicable non-U.S. regulatory authorities and the commercialization of our product candidates. This could result in higher costs or deprive us of potential product revenues and materially harm our business, financial condition and results of operations.

If we lose key management personnel and cannot recruit and retain similarly qualified replacements, our business may materially suffer.

We are highly dependent on the services of our executive officers. Our employment agreements with our executive officers do not ensure their retention. We do not currently maintain, nor do we intend to obtain in the future, “key person” life insurance that would compensate us in the event of the death or disability of any of the members of our management team. Our executive officers are critical to our success, and unanticipated loss of any of these key employees could have a material adverse impact on our business, financial condition and results of operations.

Our collaboration partners might delay, prevent or undermine the success of our product candidates.

Our operating and financial strategy for the development, nonclinical and clinical testing, manufacture and commercialization of drug candidates heavily depends on collaborating with corporations, academic institutions, licensors, licensees, and other parties. However, there can be no assurance that we will successfully establish or maintain these collaborations. If a collaboration is terminated, replacement collaborators might not be available on attractive terms, or at all.

The activities of any collaborator, including Gilead, will not be within our control and might not be within our power to influence. There can be no assurance that any collaborator will perform its obligations to our satisfaction or at all, that we will derive any revenue or profits from these collaborations, or that any collaborator will not compete with us. If any collaboration, including the Gilead Collaboration, is unsuccessful, we might require substantially greater capital to undertake development and marketing of our proposed products and might not be able to develop and market these products effectively, if at all. In addition, if Gilead does not opt-in to a program, it might lead to significant delays in introducing proposed products into certain markets and/or reduced sales of proposed products in such markets.

We may not be successful in establishing and maintaining collaborations, which could adversely affect our ability to develop certain of our product candidates.

Developing pharmaceutical products, conducting clinical studies, obtaining regulatory approval and commercializing those products are expensive and lengthy undertakings that require significant resources and expertise. We may seek to enter into collaborations, including licensing or partnering arrangements, with other companies to support the development and commercialization of any or multiple of our programs that Gilead declines to opt into or to obtain financing or share costs on these programs. If we are unable to enter into such collaborations on acceptable terms, if

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at all, we may be unable to advance certain of our product candidates through further nonclinical or clinical development. We expect to face competition in seeking appropriate partners. Moreover, collaboration arrangements are complex and time consuming to negotiate, document and implement and they may require substantial resources to maintain. We may not be successful in our efforts to establish and implement collaborations or other alternative arrangements for the development of our product candidates that Gilead declines to opt into.

If we are unable to reach agreement on favorable terms with a suitable collaboration partner for any of our product candidates that Gilead declines to opt into, we may need to limit the number of our product candidates to advance through further nonclinical or clinical development. Failure to achieve such successful collaborations would limit our options for support of the development and commercialization of our programs and for financing and would likely have a material adverse impact on our business, results of operations, financial condition and share price.

We rely on data provided by third parties that has not been independently verified and could prove to be false, misleading, or incomplete.

We rely on third-party vendors, scientists, investigators and collaborators to provide us with significant data and other information related to our projects, nonclinical studies and clinical studies, and our business. If these third parties provide inaccurate, misleading, or incomplete data, our business, prospects, and results of operations could be materially and adversely affected.

Significant disruptions of information technology systems or breaches of data security, including cybersecurity incidents, could materially and adversely affect our business, results of operations and financial condition.

We collect and maintain information in digital form and are increasingly dependent on information technology systems and infrastructure to operate our business. In the ordinary course of our business, we collect, store and transmit large amounts of confidential information, including intellectual property, proprietary business information and personal information. It is critical that we do so in a secure manner to maintain the confidentiality and integrity of such confidential information. We have outsourced elements of our information technology infrastructure and, as a result, a number of third-party vendors may or could have access to our confidential information. Our internal information technology systems and infrastructure, and those of our current and any future collaborators, contractors and consultants and other third parties on which we rely, are vulnerable to damage from computer viruses, malware, natural disasters, terrorism, war, telecommunication and electrical failures, cyberattacks, cybersecurity incidents or cyber intrusions over the Internet, attachments to emails, persons inside our organization, or persons with access to systems inside our organization.

The risk of a cybersecurity incident or security breach or disruption, particularly through cyberattacks or cyber intrusion, has escalated as the number, intensity and sophistication of attempted attacks and intrusions from around the world have increased. In addition, the prevalent use of mobile devices that access confidential information increases the risk of data security breaches, which could lead to the loss of confidential information or other intellectual property. The costs to us to mitigate network security problems, bugs, viruses, worms, malicious software programs and security vulnerabilities or incidents could be significant, and our efforts to address these problems may not be successful. If unsuccessful, these problems could cause interruptions, delays, cessation of service and other harm to our business and our competitive position, including material disruption of our product development programs. For example, any loss of clinical study data from completed or ongoing or planned clinical studies could result in delays in our regulatory approval efforts and significantly increase our costs to recover or reproduce the data.

If a computer security breach affects our systems or results in the unauthorized release of personally identifiable information, our reputation could be materially damaged. In addition, such a breach may require notification to governmental agencies, the media or individuals pursuant to various federal, state and non-U.S. privacy and security laws, if applicable, including the Health Insurance Portability and Accountability Act of 1996 (HIPAA), as amended by the Health Information Technology for Clinical Health Act of 2009, and its implementing rules and regulations, as well as regulations promulgated by the Federal Trade Commission, state breach notification law and the EU GDPR. We would also be exposed to a risk of loss or litigation and potential liability, which could materially adversely affect our business, results of operations and financial condition.

Research, development and commercialization goals may not be achieved in the timeframes that we publicly estimate, which could have an adverse impact on our business and could cause our stock price to decline.

We set goals and make public statements regarding our expectations on timing of certain accomplishments, developments and milestones under our research and development programs. The actual timing of these events can vary significantly due to a number of factors, including, the amount of time, effort and resources committed to our programs by us and any collaborators and the uncertainties inherent in the clinical development and regulatory approval process. As a result, there can be no assurance that we or any collaborators will initiate or complete clinical

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development activities, make regulatory submissions or receive regulatory approvals as planned or that we or any collaborators will be able to adhere to our current schedule for the achievement of key milestones under any of our programs. If we or any collaborators fail to achieve one or more of the milestones as planned, or Gilead does not opt-in to any of our programs, our business could be materially and adversely affected, and the price of our common stock could decline.

Developments by competitors might render our product candidates or technologies obsolete or non-competitive.

The pharmaceutical and biotechnology industries are intensely competitive. In addition, the clinical and commercial landscapes for recurrent genital herpes, HDV, HBV and transplant-related herpesviruses are rapidly changing; we expect new data from commercial and clinical-stage products to continue to emerge. We compete with organizations, some with significantly more resources, who are developing competitive product candidates. If our competitors develop effective treatments for recurrent genital herpes, HDV, HBV, transplant-related herpesviruses or any other indication or field we might pursue, and successfully commercialize those treatments, our business and prospects could be materially harmed.

Other companies with products using the same or similar mechanisms of action as ours may produce negative clinical data, which would adversely affect public and clinical communities’ perceptions of our product candidates, and may negatively impact regulatory approval of, or demand for, our potential products.

Negative data from clinical studies using a competitor’s product candidates with the same or similar mechanisms of action as ours could adversely impact the perception of the therapeutic use of our product candidates and our ability to enroll patients in clinical studies.

The clinical and commercial success of our potential products will depend in part on the public and clinical communities’ acceptance of novel classes of product candidates. Moreover, our success depends upon physicians prescribing, and their patients being willing to receive, treatments that involve the use of our product candidates we may develop in lieu of, or in addition to, existing treatments with which they are already familiar and for which more clinical data may be available. Adverse events in our nonclinical or clinical studies or those of our competitors or of academic researchers utilizing the same mechanisms of action as our product candidates, even if not ultimately attributable to our product candidates, and any resulting publicity could result in increased governmental regulation, unfavorable public perception, potential regulatory delays in the testing or approval of our product candidates, stricter labeling requirements for our product candidates that are approved, if any, and a decrease in demand for any such products.

Our ability to use our net operating loss and credit carryforwards and certain other tax attributes may be limited.

We have net operating loss carryforwards due to prior period losses generated before January 1, 2024 which if not utilized will begin to expire in 2027 for net operating loss carryforwards prior to 2018. If we are unable to generate sufficient taxable income to utilize our net operating loss carryforwards, pre-2018 carryforwards could expire unused and be unavailable to offset future income tax liabilities.

Under Sections 382 and 383 of the Internal Revenue Code of 1986, as amended (the Code), a corporation that undergoes an “ownership change” (generally defined as a greater than 50% change (by value) in its equity ownership over a three-year period) is subject to annual limitations on its ability to use its pre-change net operating loss carryforwards and other pre-change tax attributes (such as research tax credits) to offset its post-change income or taxes. We have experienced ownership changes in the past, and recent and future equity issuances may result in additional ownership change. Accordingly, some of our net operating losses or credits could expire unutilized, and our ability to utilize our net operating losses or credits to offset U.S. federal taxable income could be limited, which would result in increased future tax liability to us. We may also be subject to similar limitations at the state level.

Risks Related to Our Regulatory and Legal Environment

We are and will be subject to extensive and costly government regulation and the failure to comply with these regulations may have a material adverse effect on our operations and business.

Our product candidates are subject to extensive and rigorous domestic government regulation, including regulation by the FDA, the Centers for Medicare and Medicaid Services, other divisions of the U.S. Department of Health and Human Services, the U.S. Department of Justice, state and local governments, and their respective foreign equivalents. Both before and after approval of any product, we and our collaborators, suppliers, contract manufacturers and clinical investigators are subject to extensive regulation by governmental authorities in the United States and other countries, covering, among other things, testing, manufacturing, quality control, clinical studies, post-marketing studies, labeling, advertising, promotion, distribution, import and export, governmental pricing, price reporting and rebate requirements. Failure to comply with applicable requirements could result in one or more of the following actions:

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warning or untitled letters; unanticipated expenditures; delays in approval or refusal to approve a product candidate; voluntary or mandatory product recall; product seizure; interruption of manufacturing or clinical studies; operating or marketing restrictions; injunctions; criminal prosecution and civil or criminal penalties, including fines and other monetary penalties; exclusion from federal health care programs such as Medicare and Medicaid; adverse publicity; and disruptions to our business.

If we or our collaborators obtain regulatory approval for a particular product, the approval might limit the intended medical uses for the product, limit our ability to promote, sell, and distribute the product, require that we conduct costly post-marketing surveillance, and/or require that we conduct ongoing post-marketing studies. Once obtained, any approvals might be withdrawn, including, for example, if there is a later discovery of previously unknown problems with the product, such as a previously unknown safety issue. If we, our collaborators, our contractors or our contract manufacturers fail to comply with applicable regulatory requirements at any stage during the regulatory process, such noncompliance could result in delays in the approval of applications or supplements to approved applications, refusal by a regulatory authority (including the FDA) to review pending market approval applications or supplements to approved applications, untitled letters or warning letters, fines, import and export restrictions, product recalls or seizures, injunctions, total or partial suspension of production, civil penalties, withdrawals of previously approved marketing applications, recommendations by the FDA or other regulatory authorities against governmental contracts, and/or criminal prosecutions.

The regulatory approval processes of the FDA and comparable foreign authorities are lengthy, time consuming and inherently unpredictable, and if we or our collaborators are ultimately unable to obtain regulatory approval for our product candidates, our business will be substantially harmed.

We, or any current or future collaborators, cannot assure you that we will receive the approvals necessary to commercialize for sale any of our product candidates, or any product candidate we acquire or develop in the future. We will need FDA approval to commercialize our product candidates in the United States and approvals from applicable regulatory authorities in foreign jurisdictions to commercialize our product candidates in those jurisdictions. To obtain FDA approval of any product candidate, we must submit to the FDA an NDA demonstrating that the product candidate is safe and effective for its intended use. This requires significant research, nonclinical studies, and clinical studies. Satisfaction of the FDA’s regulatory requirements typically takes many years, depends upon the type, complexity and novelty of the product candidate and requires substantial resources for research, development and testing. We cannot predict whether our research and clinical approaches will result in drugs that the FDA considers safe and effective for their indicated uses. The FDA has substantial discretion in the approval process and might require us to conduct additional nonclinical and clinical testing, perform post-marketing studies or otherwise limit or impose conditions on any approval we obtain.

The approval process might also be delayed by changes in government regulation, future legislation or administrative action or changes in FDA policy that occur prior to or during our regulatory review. Delays in obtaining regulatory approvals might: delay commercialization of, and our ability to derive product revenues from, our product candidates; impose costly procedures on us; and diminish any competitive advantages that we might otherwise enjoy.

Even if we comply with all FDA requests, the FDA might ultimately reject one or more of our NDAs. We cannot be sure that we will ever obtain regulatory approval and commercialize any of our current or future product candidates. In foreign jurisdictions, we are subject to regulatory approval processes and risks similar to those associated with the FDA described above. We cannot assure you that we will receive the approvals necessary to commercialize our product candidates for sale outside the United States.

We and our collaborators may be subject, directly or indirectly, to applicable U.S. federal and state anti-kickback, false claims laws, physician payment transparency laws, fraud and abuse laws or similar healthcare and security laws and regulations, and health information privacy and security laws, which could expose us or them to criminal sanctions, civil penalties, contractual damages, reputational harm and diminished profits and future earnings.

Healthcare providers, physicians and others play a primary role in the recommendation and prescription of any products for which we obtain regulatory approval. If we obtain FDA approval for any of our drug candidates and begin commercializing those drugs in the United States, our operations may be subject to various federal and state fraud and abuse laws, including the federal Anti-Kickback Statute, the federal False Claims Act, and physician payment sunshine laws and regulations. Additionally, we are subject to state and non-U.S. equivalents of each of the healthcare laws described above, among others, some of which may be broader in scope and may apply regardless of the payor. These laws may impact, among other things, our proposed sales, marketing and education programs. In addition, we may be subject to patient privacy regulation by both the federal government and the states and foreign jurisdictions in which we conduct our business. If we fail to comply with any applicable federal, state or foreign legal requirement, we could be subject to penalties.

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Regulators globally are imposing greater monetary fines for privacy violations. The EU GDPR applies to any company established in the EU as well as to those outside the EU if they collect and use personal data in connection with the offering goods or services to individuals in the EU or the monitoring of their behavior. The EU GDPR enhances data protection obligations for processors and controllers of personal data, including, for example, expanded disclosures about how personal information is to be used, limitations on retention of information, mandatory data breach notification requirements and onerous new obligations on services providers. Noncompliance with the EU GDPR may result in monetary penalties of up to €20 million or 4% of worldwide revenue, whichever is higher. The EU GDPR may increase our responsibility and liability in relation to personal data that we process and we may be required to put in place additional mechanisms to ensure compliance with the EU GDPR, including as implemented by individual countries. Compliance with the EU GDPR and other changes in laws or regulations associated with the enhanced protection of certain types of personal data, such as healthcare data or other sensitive information, could greatly increase our cost of developing our products or even prevent us from offering certain products in jurisdictions that we may operate in.

The California Consumer Privacy Act (CCPA) also created new individual privacy rights for California consumers (as defined in the law) and places increased privacy and security obligations on entities handling personal data of consumers or households. The CCPA requires covered companies to provide certain disclosures to consumers about its data collection, use and sharing practices, and to provide affected California residents with ways to opt-out of certain sales or transfers of personal information. While there is currently an exception for protected health information that is subject to HIPAA and clinical study regulations, as currently written, the CCPA may impact our business activities. The uncertainty surrounding the implementation of the CCPA exemplifies the vulnerability of our business to the evolving regulatory environment related to personal data and protected health information.

Because of the breadth of these laws and the narrowness of the statutory exceptions and safe harbors available, it is possible that some of our business activities could be subject to challenge under one or more of such laws.

Violations of these laws may be punishable by criminal and/or civil sanctions, including penalties, fines and/or exclusion or suspension from federal and state healthcare programs such as Medicare and Medicaid and debarment from contracting with the U.S. government. In addition, private individuals have the ability to bring actions on behalf of the U.S. government under the federal False Claims Act as well as under the false claims laws of several states.

If any of the physicians or other providers or entities with whom we expect to do business with are found to be not in compliance with applicable laws, they may be subject to criminal, civil or administrative sanctions, including exclusions from government funded healthcare programs, which may also adversely affect our business.

We face the risk of product liability claims and might not be able to obtain insurance.

Our business exposes us to the risk of product liability claims that are inherent in drug development. If the use of one or more of our product candidates or approved drugs, if any, harms people, we might be subject to costly and damaging product liability claims brought against us by clinical study participants, consumers, health care providers, pharmaceutical companies or others selling our products. Our inability to obtain sufficient product liability/clinical study insurance at an acceptable cost to protect against potential product liability claims could prevent or inhibit the commercialization of pharmaceutical products we develop. We cannot predict all of the possible harms or side effects that might result and, therefore, the amount of insurance coverage we maintain might not be adequate to cover all liabilities we might incur. If we are unable to obtain insurance at an acceptable cost or otherwise protect against potential product liability claims, we will be exposed to significant liabilities, which might materially and adversely affect our business and financial position. If we are sued for any injury allegedly caused by our products, our liability could exceed our total assets and our ability to pay. Any successful product liability claims brought against us would decrease our cash and may adversely affect our business, stock price and financial condition.

We might be exposed to liability claims associated with the use of hazardous materials and chemicals.

Our research, development and manufacturing activities and/or those of our third-party contractors might involve the controlled use of hazardous materials and chemicals. Although we will strive to have our safety procedures, and those of our contractors, comply with federal, state and local laws and regulations for using, storing, handling and disposing of these materials, we cannot completely eliminate the risk of accidental injury or contamination from these materials. In the event of such an accident, we could be held liable for any resulting damages, and any liability could materially and adversely affect our business, financial condition and results of operations. In addition, the federal, state and local laws and regulations governing the use, manufacture, storage, handling and disposal of hazardous or radioactive materials and waste products might require us to incur substantial compliance costs that could materially and adversely affect our business, financial condition and results of operations.

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Our employees, independent contractors, consultants, collaborators and CROs may engage in misconduct or other improper activities, including noncompliance with regulatory standards and requirements, which could result in significant liability for us and harm our reputation.

We are exposed to the risk of fraud or other misconduct, including failure to:

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comply with applicable regulations of, and provide accurate information to, the FDA or comparable foreign regulatory authorities;

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comply with federal and state healthcare fraud and abuse laws and regulations and similar laws and regulations established and enforced by comparable foreign regulatory authorities;

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comply with the FCPA, the U.K. Bribery Act 2010, the PRC Criminal Law, the PRC Anti-unfair Competition Law and other anti-bribery and trade laws;

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report financial information and data accurately; or

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disclose unauthorized activities.

Misconduct could also involve the improper use or misrepresentation of information obtained during clinical studies, creating fraudulent data in our nonclinical studies or clinical studies or illegal misappropriation of product materials, which could result in regulatory sanctions, delays in clinical studies, or serious harm to our reputation.

It is not always possible to identify and deter misconduct. The precautions we take to detect and prevent this activity may not be effective in controlling unknown or unmanaged risks or losses or in protecting us from governmental investigations or other actions or lawsuits stemming from a failure to comply with such laws or regulations. Additionally, we are subject to the risk that a person or government could allege such fraud or other misconduct, even if none occurred. If any such actions are instituted against us and we are not successful in defending ourselves or asserting our rights, those actions could harm our business, results of operations, financial condition and cash flows, including through the imposition of significant fines or other sanctions.

Risks Related to Our Intellectual Property

Our business depends on protecting our intellectual property.

If we, our licensors and our collaborators do not obtain protection for our respective intellectual property rights, our competitors might be able to take advantage of our research and development efforts to develop competing drugs. Our success, competitive position and future revenues, if any, depend in part on our ability and the abilities of our licensors to obtain and maintain patent protection for our products, methods, processes and other technologies, to preserve our trade secrets, to prevent third parties from infringing on our proprietary rights and to operate without infringing the proprietary rights of third parties.

We rely upon a combination of patents, trade secret protection and contractual arrangements to protect the intellectual property related to our technologies. We will only be able to protect our products and proprietary information and technology by preventing unauthorized use by third parties to the extent that our patents, trade secrets, and contractual positions allow us to do so. We cannot be certain that we will secure any rights to any issued patents with claims that cover any of our proprietary product candidates and technologies. The patent prosecution process is expensive and time-consuming, and we may be unable to file and prosecute all necessary or desirable patent applications at a reasonable cost or in a timely manner. We could fail to identify patentable aspects of our research and development output before it is too late to obtain patent protection or before our competitors secure patents covering such discoveries. The patent process also is subject to numerous risks and uncertainties, and there can be no assurance that we will be successful in protecting our products by obtaining and defending patents.

Composition-of-matter patents relating to the active pharmaceutical ingredient are generally considered to be the strongest form of intellectual property protection for pharmaceutical products. Such patents provide protection not limited to any one method of use. Method-of-use patents protect the use of a product for the specified method(s) and do not prevent a competitor from making and marketing a product that is identical to our product for an indication that is outside the scope of the patented method. Formulation patents protect the formulation of a product and do not prevent a competitor from making and marketing a product that has an identical active pharmaceutical ingredient to our product if the product is formulated differently than the patented formulation. We rely on a combination of these and other types of patents to protect our product candidates, and there can be no assurance that our intellectual property will create and sustain the competitive position of our product candidates.

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Biotechnology and pharmaceutical product patents involve highly complex legal and scientific questions. Any patent applications that we own or license may fail to result in issued patents. In addition, the U.S. Patent and Trademark Office (USPTO) and patent offices in other jurisdictions often require that patent applications concerning pharmaceutical and/or biotechnology-related inventions are limited or narrowed substantially to cover only the specific innovations exemplified in the patent application, thereby limiting the scope of protection against competitive challenges. As a result, even if we or our licensors obtain patents, the patents might be substantially narrower than anticipated.

If patents successfully issue from our applications, third parties may challenge their validity or enforceability, which may result in such patents being narrowed, invalidated, or held unenforceable. Even if our patents and patent applications are not challenged by third parties, those patents and patent applications may not prevent others from designing around our claims and may not otherwise adequately protect our product candidates.

Patent and other intellectual property protection is crucial to the success of our business and prospects, and there is a substantial risk that such protections, if obtained, will prove inadequate. The legal systems of certain countries, including China, do not always favor the enforcement of patents, trade secrets, and other intellectual property rights, particularly those relating to pharmaceutical and biotechnology products, which could make it difficult for us to stop infringement of our patents, misappropriation of our trade secrets, or marketing of competing products in violation of our proprietary rights.

Beyond the protection afforded by patents, we seek to rely on trade secret protection and confidentiality agreements to protect proprietary know-how, information, or technology that is not covered by our patents. Although our agreements require all of our employees to assign their inventions to us, and we require all of our employees, consultants, advisors, collaborators, contractors and any third parties who have access to our trade secrets, proprietary know-how and other confidential information and technology to enter into appropriate confidentiality agreements, we cannot be certain that our trade secrets, proprietary know-how and other confidential information and technology will not be subject to unauthorized disclosure or that our competitors will not otherwise gain access to or independently develop substantially equivalent trade secrets, proprietary know-how and other information and technology. If we are unable to prevent unauthorized disclosure of our intellectual property related to our product candidates and technology to third parties, we may not be able to establish or maintain a competitive advantage in our market, which could materially adversely affect our business and operations.

We may incur substantial costs as a result of litigation or other proceedings relating to our patents and other intellectual property rights.

We may in the future be involved in legal or administrative proceedings involving our intellectual property, including infringement of our intellectual property by third parties. These lawsuits or proceedings likely would be expensive, consume time and resources and divert the attention of managerial and scientific personnel, even if we were successful in stopping the infringement of such patents. There is a risk that these proceedings will decide that such patents or other intellectual property rights are not valid and that we do not have the right to stop the other party from using our inventions. There is also the risk that, even if the validity of such patents is upheld, the court or administrative agency will refuse to stop the other party on the ground that such other party’s activities do not infringe our rights to such patents. If we were not successful in defending our intellectual property, our competitors could develop and market products based on our discoveries, which may reduce demand for our products.

We may infringe the intellectual property rights of others, which may prevent or delay our product development efforts and stop us from commercializing or increase the costs of commercializing our product candidates.

Our success will depend in part on our ability to operate without infringing the proprietary rights of third parties. Our competitors may have filed, and may in the future file, patent applications covering products and technologies similar to ours. Any such patent application may have priority over our patent applications, which could further require us to obtain rights from third parties to issued patents covering such products and technologies. We cannot guarantee that the manufacture, use or marketing of any product candidates that we develop will not infringe third-party patents.

If a patent infringement suit were brought against us, we may be forced to stop or delay developing, manufacturing, or selling potential products that are claimed to infringe a third party’s intellectual property, unless that third party grants us rights to use its intellectual property. In such cases, we may be required to obtain licenses to patents or proprietary rights of others to continue development, manufacture or sale of our products. If we are unable to obtain a license or develop or obtain non-infringing technology, or if we fail to defend an infringement action successfully, or if we are found to have infringed a valid patent, we may incur substantial costs and monetary damages, encounter significant delays in bringing our product candidates to market and be precluded from manufacturing or selling our product candidates, any of which could harm our business significantly.

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The cost of maintaining our patent protection globally is high and requires continuous review and compliance. We may not be able to effectively maintain our intellectual property position throughout the major markets of the world.

The USPTO and foreign patent authorities require maintenance fees, payments and continued compliance with a number of procedural and documentary requirements. Noncompliance may result in abandonment or lapse of patents or patent applications and a partial or complete loss of patent rights in the relevant jurisdiction. Such a loss could reduce royalty payments for lack of patent coverage from our collaboration partners or may result in competition, either of which could have a material adverse effect on our business.

We have made, and will continue to make, certain strategic decisions in balancing the costs and the potential protections afforded by the patent laws of certain countries. As a result, we may not be able to prevent third parties from practicing our inventions in all countries, or from selling or importing products made using our inventions in and into the United States or other countries. Third parties may use our technologies in territories in which we have not obtained patent protection to develop their own products and may infringe our patents in territories which provide inadequate enforcement mechanisms. Such third-party products may compete with our product candidates, and our patents or other intellectual property rights may not be effective or sufficient to prevent them from competing. Such competition could materially and adversely affect our business and financial condition.

Intellectual property rights do not address all potential threats to any competitive advantage we may have.

The degree of future protection afforded by our intellectual property rights is uncertain because intellectual property rights have limitations, and intellectual property rights may not adequately protect our business or permit us to maintain our competitive advantage. The following examples are illustrative:

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Others may be able to make compounds that are the same as, or similar to, our current or future product candidates but that are not covered by the claims of the patents that we own or have exclusively licensed.

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We or any of our licensors or strategic partners might not have been the first to make the inventions covered by the issued patents or pending patent applications that we own or have exclusively licensed.

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We or any of our licensors or strategic partners might not have been the first to file patent applications covering certain of our inventions.

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Others may independently develop similar or alternative technologies or duplicate any of our technologies without infringing our intellectual property rights.

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The prosecution of our pending patent applications may not result in granted patents.

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Granted patents that we own or have exclusively licensed may not provide us with any competitive advantages, or may be held invalid or unenforceable, because of legal challenges by our competitors.

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Patent protection on our product candidates may expire before we are able to develop and commercialize the product, or before we are able to recover our investment in the product.

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Our competitors might conduct research and development activities in the United States and other countries that provide a safe harbor from patent infringement claims for such activities, as well as in countries in which we do not have patent rights and may then use the information learned from such activities to develop competitive products for sale in markets where we intend to market our product candidates.

Risks Related to Our Common Stock

Our amended and restated bylaws provide that the Court of Chancery of the State of Delaware will be the sole and exclusive forum for certain types of actions and proceedings that may be initiated by our stockholders, which could limit our stockholders’ ability to bring a claim in a judicial forum they find favorable for disputes with us or our directors, officers or other employees.

Our amended and restated bylaws provide that, with certain limited exceptions, unless we consent to the selection of an alternative forum, the Court of Chancery of the State of Delaware is the sole and exclusive forum for (1) any derivative action or proceeding brought on our behalf; (2) any action asserting a claim of breach of fiduciary duty owed by any of our current or former directors, officers or other employees to us or to our stockholders; (3) any action asserting a claim arising pursuant to the Delaware General Corporation Law, or our certificate of incorporation or bylaws (as each may be amended from time to time); or (4) any action asserting a claim governed by the internal affairs doctrine. Alternatively, if such court does not have jurisdiction, the Superior Court of Delaware, or, if such

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other court does not have jurisdiction, the United States District Court for the District of Delaware, will be the sole and exclusive forum for such actions and proceedings. The choice of forum provision may limit a stockholder’s ability to bring a claim in a judicial forum that it finds favorable for disputes with us or our directors, officers, or other employees, which may discourage such lawsuits against us and our directors, officers, and other employees. Alternatively, if a court were to find the choice of forum provision contained in our amended and restated bylaws to be inapplicable or unenforceable in an action, we may incur additional costs associated with resolving such action in other jurisdictions, which could have a material adverse impact on our business. The choice of forum provision in our amended and restated bylaws will not preclude or contract the scope of exclusive federal or concurrent jurisdiction for actions brought under the federal securities laws, including the Exchange Act or the Securities Act, or the respective rules and regulations promulgated thereunder.

The price of our common stock might fluctuate significantly, and you could lose all or part of your investment.

The price of our common stock fluctuates widely. Continued volatility in the market price of our common stock might prevent a stockholder from being able to sell shares of our common stock at or above the price paid for such shares. The trading price of our common stock may continue to be volatile and subject to wide price fluctuations in response to various factors, many of which are beyond our control, such as the progress, results and timing of our clinical and nonclinical studies and other studies involving our product candidates, the success or failure of our product candidates, the receipt or loss of required regulatory approvals for our product candidates, the availability of capital or the other risks discussed in this “Risk Factors” section.

Item 1B. Unresolved Staff Comments

None.

Item 1C. Cybersecurity

Risk Management and Strategy

We recognize the critical importance of developing, implementing, and maintaining robust cybersecurity measures to help maintain the security, confidentiality, integrity, and availability of our business systems and confidential information, including personal information and intellectual property. Our cybersecurity program includes systems and processes that are designed to assess, identify and manage material risks from cybersecurity threats and includes: maintenance and monitoring of information security policies aligned with global regulatory controls; user and employee awareness of cyber policies and practices; simulated phishing exercises; information systems configuration management; identity and information asset protection; infrastructure security systems; and cyber threat operations with regular monitoring and threat hunting. This program includes processes to oversee and identify material risks from cybersecurity threats associated with our use of third-party service providers. We also maintain a cyber incident response plan designed to assist us in identifying, responding to and recovering from cybersecurity incidents. We use the findings from these and other processes to help us improve our information security practices, procedures and technologies. We also collaborate with third parties to assess the effectiveness of our cybersecurity program. These include cybersecurity assessors, consultants, and other external cybersecurity experts to assist in the identification, verification, and validation of material risks from cybersecurity threats, as well as to support associated mitigation plans when necessary.

Cybersecurity is integrated into our overall risk management systems, including our annual enterprise risk management, internal controls, business continuity and crisis management, third-party risk management, insurance risk management, and employee compliance processes. Our Cyber Incident Response Team, comprised of our Vice President, General Counsel and Corporate Secretary, our Executive Director, Accounting and Treasury, and our Executive Director, Information Technology, consults with, or provides input to each of these programs to ensure that material risks from cybersecurity threats are appropriately assessed, identified, and managed.

As of the date of this report, there have been no cybersecurity threats, including as a result of any previous cybersecurity incidents, that have materially affected or are reasonably likely to materially affect us, including our business, strategy, results of operations, or financial condition. For additional description of cybersecurity risks and potential related impacts on the Company, refer to the risk factor captioned “Significant disruptions of information technology systems or breaches of data security, including cybersecurity incidents, could materially and adversely affect our business, results of operations and financial condition” in “Item 1A. Risk Factors.”

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Governance

While our board of directors has oversight responsibility for risk management generally, the Audit Committee is specifically responsible for overseeing our cybersecurity risk management program to ensure cybersecurity risks are identified, assessed, managed, and monitored. Our Executive Director, Information Technology, who has over 15 years of experience in the cybersecurity field, provides periodic updates to the Audit Committee in this regard, and details our cybersecurity program supported by key performance indicators across the range of cybersecurity functions related to risk management and governance, identity and information asset protection, core security and endpoint security, and cyber threat operations. These updates include descriptions of cybersecurity incidents, including those associated with our third-party service providers. The Audit Committee is responsible for updating our full board of directors on material risks from cybersecurity incidents or threats.

Item 2. Properties

We lease office space for corporate and administrative functions and laboratory space in South San Francisco, California under a sublease that expires in October 2025. Our China subsidiary leases a registrational office in Shanghai, which expires in March 2024.

We believe these leased facilities are adequate for our current needs and that additional space will be available in the future on commercially reasonable terms as needed.

Item 3. Legal Proceedings

We are not a party to any material legal proceedings at this time. From time to time, we may be subject to various legal proceedings and claims that arise in the ordinary course of our business activities. Although the results of litigation and claims cannot be predicted with certainty, we do not believe we are party to any claim or litigation the outcome of which, if determined adversely to us, would individually or in the aggregate be reasonably expected to have a material adverse effect on our business. Regardless of the outcome, litigation can have an adverse effect on us because of defense and settlement costs, diversion of management resources and other factors.

Item 4. Mine Safety Disclosures

Not applicable.

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PART II

Item 5. Market for Registrant’s Common Equity, Related Stockholder Matters and Issuer Purchases of Equity Securities

Market Information for Common Stock

Our common stock is traded under the symbol “ASMB” and is quoted on The Nasdaq Global Select Market.

Holders of Record

As of March 22, 2024, there were 47 stockholders of record, which excludes stockholders whose shares were held in nominee or street name by brokers.

Dividend Policy

We have never declared or paid any dividends and do not anticipate paying any dividends on our common stock in the foreseeable future.

Recent Sales of Unregistered Securities

There were no unregistered sales of equity securities in 2023.

Purchases of Equity Securities by the Issuer and Affiliated Purchasers

We did not purchase any of our registered equity securities during the period covered by this Annual Report on Form 10-K.

Reverse Stock Split

On January 31, 2024, following approval by our stockholders, our board of directors approved the implementation of a reverse stock split of our common stock at a ratio of 1-for-12 (the Reverse Stock Split). The Reverse Stock Split was effective as of February 9, 2024, and our common stock began trading on the Nasdaq Global Select Market on a post-split basis on February 12, 2024. All share and per share amounts of our common stock presented in this Annual Report on Form 10-K have been retroactively adjusted to reflect the Reverse Stock Split.

Item 6. [Reserved]

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Item 7. Management’s Discussion and Analysis of Financial Condition and Results of Operations

The following discussion and analysis of our financial condition and results of operations should be read in conjunction with our consolidated financial statements and the related notes thereto and other financial information appearing elsewhere in this Annual Report on Form 10-K. The following discussion contains forward-looking statements that involve risks and uncertainties. Our actual results could differ materially from those expressed or implied in any forward-looking statements as a result of various factors, including those set forth in this Form 10-K under “Item 1A. Risk Factors.”

Overview

We are a biotechnology company developing innovative therapeutics targeting serious viral diseases with the potential to improve the lives of patients worldwide. Our pipeline includes two helicase-primase inhibitors (HPI) targeting recurrent genital herpes, an orally bioavailable hepatitis delta virus (HDV) entry inhibitor, a clinical stage capsid assembly modulator (CAM) designed to disrupt the replication cycle of hepatitis B virus (HBV) at several key points with the aim of achieving finite treatment and functional cures and research programs focused on the discovery of therapeutics to treat devastating viral diseases, including a non-nucleoside polymerase inhibitor (NNPI) targeting transplant-related herpesviruses and a small molecule interferon-α (IFN-α) receptor (IFNAR) agonist targeting HBV and HDV.

Our Strategy

We have recruited an accomplished leadership team and research and development organization, with a collective team track record of over 15 approved drugs in viral diseases, including hepatitis. Our collaboration with Gilead Sciences, Inc. (Gilead and the Gilead Collaboration) also brings us an industry leading partner with a shared vision of providing differentiated antiviral treatments to patients. For additional information regarding the Gilead Collaboration, see “Collaboration and License Agreements—Gilead Sciences, Inc.”

Our Clinical Programs and CTA-Enabling Programs

Recurrent Genital Herpes/HSV-1 and HSV-2

In August 2022, we introduced our first programs outside of hepatitis. Among our new viral targets is recurrent genital herpes. Genital herpes can be caused by either herpes simplex virus type 1 (HSV-1) or herpes simplex virus type 2 (HSV-2). HSV-1 and HSV-2 are acquired by oral or genital contact either during symptomatic or asymptomatic reactivation of the virus. Both viruses replicate in neurons, where they can remain latent for the rest of the patient’s life and periodically reactivate, with the virus spreading and replicating in epithelial tissues. Initial infection can be asymptomatic or can be marked by symptoms, including localized pain and painful lesions. Genital herpes recurrence is common and can cause painful genital lesions that can lead to increased transmission and debilitate patients, and symptoms may become more serious with additional episodes. Additional complications include increased risk of HIV infection, as well as associated psychological stress and isolationary thoughts, depression and suicidal ideation. Immunocompromised patients may experience more severe and prolonged symptoms due to increased recurrence rates. While genital herpes can be caused by either HSV-1 or HSV-2, recurrences are more likely to be experienced by patients infected by HSV-2.

There are an estimated 800 million people globally with HSV-2, with an estimated 32 million in the United States and 31 million in France, Germany, Italy and Spain (collectively, the EU4) and the United Kingdom (UK). Only approximately 13% of that population is aware of the infection and have been diagnosed. Awareness and diagnostic rates are impacted due to asymptomatic infections and low screening rates in adults and adolescents due to high false positive rates with current diagnostic assays.

HPIs are antiviral agents in development for HSV-1 and HSV-2, with a clinically validated mechanism of action. HPIs inhibit the HSV helicase-primase complex, which is a unique viral enzyme complex without a human homolog, consisting of helicase, primase and cofactor subunits. Both of these subunits have functions that are essential for viral DNA replication and are conserved across HSV-1 and HSV-2. Unlike nucleoside analogs, these compounds do not require phosphorylation by the HSV thymidine kinase (TK) and ongoing viral replication to become active drugs. As a result, HPIs are active immediately upon reactivation of latent HSV-1 and HSV-2. Furthermore, HPIs are active

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against TK-deficient HSV-1 and HSV-2, which is a major mechanism of resistance to nucleoside analogs. In February 2023, we announced the nomination of our first herpesvirus development candidate, ABI-5366 (5366), a long-acting HPI for treatment of recurrent genital herpes, to progress toward CTA-enabling studies. In connection with the Gilead Collaboration, in October 2023, we acquired the rights to ABI-1179 (1179), Gilead’s HPI program, which is structurally differentiated from 5366.

Currently, there are three antiviral drugs (all nucleoside analogs) that have been approved in the United States and the EU4/UK for the treatment of genital herpes. No new drugs have been approved to treat genital herpes for more than 25 years. In addition to the approved nucleoside analogs, agents such as local anesthetics or analgesics may be used to alleviate local symptoms of minor pain and discomfort.

Nucleoside analogs can be administered as episodic therapy as individual outbreaks arise or daily as chronic suppressive therapy for those with high post-exposure recurrences. However, these agents are only partially effective at controlling the infection or reducing transmission risk. With current nucleoside analog therapies, only one out of three recurrent genital herpes patients with six or more recurrences per year are able to make it through a year of treatment without a recurrence. There are still high titer (greater than 104 HSV-2 DNA copies/mL) shedding episodes under this current standard of care for HSV-2, which can lead to recurrences and transmission of genital herpes.

Based on the limitations of current therapies, we see a path to advancing the treatment paradigm for patients suffering from recurrent genital herpes. To reach that goal, we identified an opportunity to develop a potent, long-acting HPI for recurrent genital herpes, 5366, which has demonstrated a strong nonclinical profile, with low nanomolar potency in vitro against both HSV-1 and HSV-2 clinical isolates, exceptionally low plasma clearance rates in multiple nonclinical models and a projected human half-life of more than seven days. This nonclinical profile has led us to target 5366 for development as a long-acting treatment with the potential to be administered orally or as an injectable.

To date, 5366 has also demonstrated a favorable nonclinical safety profile in Good Laboratory Practice (GLP) toxicology studies, with high safety margins and minimal potential for off-target effects. We currently anticipate the initiation of clinical studies with 5366 by mid-2024.

In addition, we are also advancing 1179, a second, structurally-differentiated HPI with single digit nM potency against HSV-1 and HSV-2 and a nonclinical pharmacokinetics (PK) profile strongly supporting a potential long-acting treatment by oral and injectable administration. GLP toxicology studies are underway and clinical studies are expected to begin by the end of 2024.

Our HBV and HDV Programs

The World Health Organization (WHO) estimates that 296 million people worldwide are chronically infected with HBV as of 2019, and 1.5 million new infections occur each year. HBV is a leading global cause of chronic liver disease and liver transplants, and the WHO estimates that 820,000 people died in 2019 from HBV, mostly due to cirrhosis and hepatocellular carcinoma. Of the 296 million people living with chronic HBV infection, only approximately 30.4 million, or 10.5%, were aware of their infection, and only approximately 6.6 million, or 22%, of those diagnosed received treatment. HBV is a highly prevalent disease that infects more than three times the number of people infected with hepatitis C virus and HIV infections combined, according to the WHO.

HDV is a “satellite virus,” because it can only infect people (1) who are already infected with HBV or (2) at the same time as a person is infected with HBV. HDV affects a subset of approximately 12 million HBV infected patients. These patients, which comprise an estimated 4.5% of hepatitis B surface antigen (HBsAg) positive patients, experience a substantially increased disease burden, as they account for 18% of cirrhosis and 20% of hepatocellular carcinoma associated with HBV. HDV is considered the most severe form of hepatitis, as 70% of HDV patients progress to cirrhosis within ten years. While HDV is less prevalent in the United States, it is a significant and serious health problem with inadequate treatment in many parts of Europe, Africa, the Middle East, East Asia and parts of South America. HDV may be significantly underdiagnosed, because there were no HDV-targeted therapies approved until very recently, and the first therapy approved is only approved in the European Union. HDV is known to accelerate disease progression and increase the incidence of liver cirrhosis and liver cancer, which results in higher morbidity and mortality rates than HBV alone.

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The current standard of care for chronic HBV infection, nucleos(t)ide analog reverse transcriptase inhibitors (NrtIs), are taken life-long and reduce, but do not eliminate, the virus and result in very low cure rates. No new mechanisms of action (MOA) have been approved for chronic HBV infection in over 25 years. The focus of our HBV program is to improve outcomes and increase the number of patients diagnosed and treated through the development of finite and curative therapies targeting an orthogonal MOA.

The current standard of care treatment for HDV is off-label pegylated IFN-α injected weekly or, in some regions, a large, complex molecule that requires daily injections. There are no approved HDV treatments in the United States, and there is only one approved HDV treatment in Europe. We believe a safe and effective oral small molecule entry inhibitor would be a significant innovation for patients living with HDV, which face a significant and immediate disease burden.

HDV Entry Inhibitor

HDV is a small RNA virus that encodes just two viral proteins and relies on host enzymes as well as the HBsAg from HBV to replicate, which limits the number of HDV-specific antiviral targets. Similar to HBV, HDV utilizes HBsAg to enter hepatocytes by binding the cellular transmembrane protein sodium taurocholate co-transporting peptide (NTCP). NTCP is highly expressed on human hepatocytes, where it serves as one of several proteins involved in the transport of bile acids. The binding of specific small or large molecules to NTCP has been shown to effectively inhibit the interaction of HBsAg with NTCP, which prevents HBV and HDV from infecting hepatocytes.

The inhibition of HBV and HDV infection by molecules that bind NTCP has been demonstrated in vitro, in animal models and clinically. Notably, Bulevirtide, a peptide blocker of NTCP, is the only approved therapy for HDV (approved in the European Union (the EU). The binding of NTCP-targeted HBV/HDV entry inhibitors to NTCP has also been shown to inhibit the transport of certain bile acids into cells, which results in plasma elevations of bile acids; this effect has been well tolerated clinically and may serve as a biomarker of pharmacologically active concentrations of drug in the plasma.

We believe a safe and effective oral small molecule entry inhibitor would be a significant innovation for patients living with HDV and could significantly improve treatment uptake and diagnosis rates, especially when compared with currently available injectable products.

In March 2022, we announced our research program focused on a novel, orally bioavailable small molecule approach to inhibit entry of HBV and HDV by targeting NTCP, and in September 2023, we nominated ABI-6250 (6250). In nonclinical studies, 6250 demonstrated low nanomolar potency against all HBV/HDV genotypes, favorable selectivity for NTCP versus other bile acid transporters, good oral bioavailability and a PK profile in nonclinical species projected to support once-daily oral dosing.

At the European Association for the Study of the Liver's (EASL) International Liver CongressTM in June 2023 and the International HBV Meeting in September 2023, we presented nonclinical characterization of the potencies and properties of our novel class of highly potent, small molecule, orally-bioavailable entry inhibitors. We expect to initiate Phase 1a clinical studies of 6250 by the end of 2024.

Capsid Assembly Modulator

HBV is a DNA virus that infects hepatocytes and establishes a reservoir of covalently closed circular DNA (cccDNA), a unique viral DNA moiety that resides in the nucleus of HBV-infected hepatocytes and is associated with viral persistence and chronic infection. No currently approved oral therapies target cccDNA activity directly, which makes molecules that can modulate cccDNA generation or disrupt its function. As a result, we have worked to discover and develop compounds targeting the core protein, a viral protein involved in numerous aspects of the HBV replication cycle, including the generation of HBV cccDNA.

A benchmark for therapeutic agents aiming to decrease cccDNA levels is the use of several key viral antigens as surrogate biomarkers of active cccDNA. The same biomarkers can be used in both primary human hepatocytes and patients. On this basis, our next-generation CAM, ABI-4334 (4334), has shown nonclinical proof of principle. In a variety of cell culture models, 4334 has demonstrated the ability to reduce production of viral HBV DNA levels as

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well as the surrogate markers for cccDNA establishment: HBV e antigen (HBeAg), HBV core-related antigen (HBcrAg) and viral pre-genomic RNA (pgRNA).

As a next-generation CAM, 4334 has been optimized to potently disrupt viral replication (MOA #1) and prevent the establishment and replenishment of new cccDNA (MOA #2). In contrast, while active against MOA #1, first-generation CAMs have not demonstrated adequate potency to sufficiently block cccDNA formation (MOA #2). Further, the current standard of care, NrtIs, impacts the viral life cycle after establishment of cccDNA and can only inhibit production of new viral particles, and it does so incompletely. In mid-2021, we announced the selection of 4334, which was internally discovered, for clinical development. The chemical scaffold of 4334 is novel and distinct from all our prior CAM candidates.

We believe that 4334 has a best-in-class nonclinical profile, with single-digit nanomolar potency against MOA #1 and MOA #2, pan-genotypic activity, an improved resistance profile and a favorable safety profile. Through mechanistic studies presented at multiple conferences, we have demonstrated that 4334 promotes the formation of empty capsids by acceleration of capsid assembly, prevents the formation of cccDNA by disrupting incoming capsids, and prematurely disrupts capsids containing duplex linear DNA, the precursor for integrated HBV DNA.

We expect to initiate Phase 1b clinical studies of 4334 by mid-2024.

Research Programs

Transplant-Associated Herpesviruses

In August 2022, in connection with our announcement of our HPI program, we also introduced our NNPI research program, targeting transplant-associated herpesviruses. In a transplant setting, when patients are experiencing immunosuppression, they are at high risk of uncontrolled viral replication and severe disease brought on by one or more herpesviruses, including cytomegalovirus (CMV), HSV-1, HSV-2 and varicella zoster virus (VZV). Each of these herpesviruses are highly prevalent, as approximately (1) 60% of transplant patients are CMV-positive; (2) 60% of transplant patients are HSV-positive; and (3) 80% of transplant patients are VZV-positive. These viruses establish lifelong latent infections and frequently reactivate in transplant patients due to the use of immunosuppressive drugs following the transplant. These uncontrolled viral infections increase the risk of severe disease and serious complications, including organ rejection, graft loss and death, and impacted approximately 60,000 patients in 2018 in the United States and EU4/UK.

While there are approved antivirals that are administered in a transplant setting. However, currently approved antivirals are not broad spectrum and pose the risk of potentially serious side effects and drug-drug interactions. As a result of these limitations, we identified an opportunity to develop an oral pan-herpes NNPI for these transplant-associated herpesvirus infections, which could greatly advance treatment. Our research team has discovered multiple chemical series of potent, broad-spectrum herpesvirus polymerase inhibitors. In addition, Gilead exclusively licensed us its NNPI program, and we believe the combined effort will speed candidate nomination and enhance our chance of clinical success.

IFNAR Agonist

In July 2022, we introduced our new research program advancing a novel, small molecule IFNAR agonist designed to selectively activate the IFN-α pathway within the liver and offer the convenience of oral dosing. IFN-α is a subcutaneous injectable immune modulatory therapy approved for HBV that has demonstrated functional cure in some HBV patients, but its poor tolerability profile significantly limits its use. Substantial side effects include flu-like symptoms, cytopenias, serious depression and psychiatric effects. In addition, multiple contraindications limit its use, and it requires weekly injections that result in systemic exposure for up to a year.

By focusing exposure on the liver, our investigational IFNAR agonist program aims to engage IFN-α’s validated antiviral and immune modulatory mechanisms, retaining the efficacy of IFN-α while reducing systemic exposure to improve tolerability. Lead optimization of multiple IFNAR agonists is in progress.

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Collaboration and License Agreements

Gilead Sciences, Inc.

On October 15, 2023, we entered into an Option, License and Collaboration agreement (the Gilead Collaboration Agreement) with Gilead pursuant to which Gilead (1) exclusively licensed to us its HPI program and its NNPI program, while retaining opt-in rights to these programs and (2) has an option to take an exclusive license, on a program-by-program basis, to all of our other current and future pipeline programs. During the 12-year collaboration term (subject to payment of certain extension fees) and for a specified period thereafter, Gilead may exercise its opt-in rights, on a program-by-program basis, at one of two timepoints—completion of a certain Phase 1 study or completion of a certain Phase 2 study for the first product within the program—upon payment of an opt-in fee ranging from $45.0 million to $125.0 million per program depending on the type of program and when the option is exercised. Pursuant to the Gilead Collaboration Agreement, Gilead made an $84.8 million upfront cash payment to us.

If Gilead exercises its opt-in right to any current or future program under the collaboration, we are eligible to receive up to $330.0 million in potential regulatory and commercial milestones on that program, in addition to royalties ranging from the high single-digits to high teens, depending on the clinical stage of the program at the time of the opt-in. Following Gilead’s exercise of its option for each of our programs, we may opt in to cover 40% of the research and development costs in the United States and share 40% of the profits and operating loss in the United States for products within the program in lieu of receiving milestones and royalties for that program in the United States, unless we later opt out of the cost/profit share for the program. Prior to Gilead’s potential exercise of its opt-in, we will be primarily responsible for all discovery, research and development on both our programs and the two Gilead-contributed programs. Following Gilead’s opt-in, Gilead will control the further discovery, research, development, and commercialization on any optioned programs. During the term, Gilead will continue to support the collaboration through extension fees of $75.0 million in each of the third, fifth and seventh years of the collaboration.

The Gilead Collaboration Agreement is subject to termination by either party for the other party’s uncured, material breach or insolvency. Subject to certain limitations, we and Gilead both have certain termination for convenience rights, upon sufficient prior written notice, with respect to programs that one party in-licenses from the other (subject to Gilead’s option rights), and with respect to Gilead, for programs it has option rights to subject to certain time limitations with respect to existing Company programs). Gilead also has a right to terminate the collaborative activities under the Gilead Collaboration Agreement at certain specified points during the collaboration term. Other customary termination rights are further provided in the Gilead Collaboration Agreement.

We and Gilead also entered into a Common Stock Purchase Agreement and an Investor Rights Agreement (together, the Gilead Equity Agreements), pursuant to which Gilead made an upfront equity investment of $15.2 million by purchasing from us 1,089,472 shares of our common stock at a purchase price of $13.92 per share. If we complete an equity financing (or series of financings) by July 15, 2024 that results in at least $30 million of proceeds to us, then, subject to approval by our stockholders (which was obtained on January 31, 2024), we may require Gilead to purchase additional shares of common stock from us in an amount that results in Gilead owning 29.9% of our then-outstanding voting capital stock. If we do not complete the equity financing or do not require Gilead to purchase the additional shares, Gilead may elect to purchase additional shares of common stock from us in an amount that results in Gilead owning 29.9% of our then-outstanding voting capital stock. The purchase price per share for additional shares purchased by Gilead will be equal to the lesser of (1) a 35% premium to the 30-day volume weighted average price immediately prior to the date of purchase or (2) a 35% premium to the 30-day volume weighted average price immediately prior to delivery by Gilead of notice of the anticipated closing date. The Gilead Equity Agreements also include a three-year standstill provision and two-year lockup provision, each with customary exceptions, and provide Gilead with certain other stock purchase rights and registration rights, as well as the right to designate two directors (or, alternatively, board observers at Gilead’s election) to our board of directors. In December 2023, Gilead designated Tomas Cihlar, Ph.D. to serve on our board of directors, and in March 2024, Gilead designated Robert D. Cook II to serve on our board of directors.

BeiGene, Ltd.

In July 2020, we entered into a Collaboration Agreement (the BeiGene Agreement) with BeiGene, Ltd. (BeiGene), granting BeiGene an exclusive, royalty-bearing license to develop and commercialize products containing vebicorvir

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(VBR), ABI-H2158 (2158) and ABI-H3733 (3733) in the People’s Republic of China, Hong Kong, Taiwan and Macau (the Territory).

Under the BeiGene Agreement, we and BeiGene will collaborate on development activities with respect to the licensed products in accordance with a mutually agreed upon development plan.

Pursuant to the terms of the BeiGene Agreement, BeiGene paid us an upfront amount of $40.0 million, and we were eligible to receive up to approximately $500.0 million in milestone payments, comprised of up to $113.8 million in development and regulatory and $385.0 million in net sales milestone payments. In September 2021, we discontinued development of 2158 following the observation of elevated alanine transaminase (ALT) levels in the Phase 2 clinical study consistent with drug-induced hepatotoxicity, in July 2022, we discontinued VBR because it did not achieve functional cure or finite treatment in our two- and three-drug combination studies and in March 2023, we prioritized 4334 over 3733 based on data from clinical Phase 1 studies of both candidates and chronic toxicology observation for 3733 and announced that we would seek partnering opportunities for the CAMs. In conjunction with the Gilead Collaboration Agreement, we elected to no longer seek partnering or further development of 3733. As of our discontinuation of 3733 development, there are no remaining products in development that have been licensed to BeiGene.

The BeiGene Agreement also contains provisions such as representations and warranties of the parties, terms as to governance of the collaboration, commercialization and regulatory responsibilities of the parties, and manufacturing and supply, including potential adjustments in the event supply costs exceed certain levels. In addition, during the term of the BeiGene Agreement, neither party will commercialize any competing products in the Territory.

BeiGene may terminate the BeiGene Agreement for convenience at any time upon 90 days’ advance written notice to us. The BeiGene Agreement also contains customary provisions for termination by either party, including in the event of breach of the BeiGene Agreement, subject to cure.

Indiana University Research and Technology Corporation

In September 2013, we entered into an exclusive license agreement (the IURTC License Agreement) with Indiana University Research and Technology Corporation (IURTC) pursuant to which we acquired, with rights to sublicense, the rights to develop and commercialize products associated with multiple patents and patent applications covering aspects of our HBV program held by IURTC. As part of this agreement, we were obligated to make milestone payments based upon the successful accomplishment of clinical and regulatory milestones. The aggregate amount of all performance milestone payments under the IURTC License Agreement, should all performance milestones through development be met, was $0.8 million, with a portion related to the first performance milestone having been paid. Under the IURTC License Agreement, we were also obligated to pay IURTC royalties based on net sales of the licensed technology ranging from 0.5% to 1.75%. In addition, under the IURTC License Agreement, we paid annual diligence maintenance fees of $0.1 million. Milestone payments received by IURTC were fully creditable against the annual diligence maintenance fee for the year in which the milestone payments were received.

In January 2024, we notified the Indiana University Innovation and Commercialization Office and IURTC that we had decided to terminate the IURTC License Agreement. The termination of the License Agreement will be effective on April 11, 2024, 90 days following the delivery of the termination notice.

Operations

We currently have corporate and administrative offices and research laboratory space in South San Francisco, California as well as a registrational office, but no employees, in China.

Since our inception, we have had no revenue from product sales and have funded our operations principally through debt financings prior to our initial public offering in 2010 and through equity financings and collaborations since then. Our operations to date have been primarily limited to organizing and staffing our company, licensing our product candidates, discovering and developing our product candidates, maintaining and improving our patent portfolio and raising capital.

We have generated significant losses to date, and we expect to continue to generate losses as we develop our product candidates. As of December 31, 2023, we had an accumulated deficit of $785.7 million primarily as a result of research

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and development expenses and general and administrative expenses. Because we do not generate revenue from any of our product candidates, our losses will continue as we further develop and seek regulatory approval for, and commercialize, our product candidates. Additionally, we expect our research and development expenses to increase over the coming years as we continue the development of our product candidates. As a result, our operating losses are likely to be substantial over the next several years and thereafter if none of our product candidates are approved or successfully launched. We are unable to predict the extent of any future losses or when we will become profitable, if at all.

Critical Accounting Estimates

Our management’s discussion and analysis of our financial condition and results of operations is based on our consolidated financial statements, which we have prepared in accordance with accounting principles generally accepted in the United States. The preparation of these consolidated financial statements requires us to make estimates and assumptions that affect the reported amounts of assets and liabilities and the disclosure of contingent assets and liabilities at the date of the financial statements, as well as the reported amounts of revenues and expenses during the reporting periods. Note 2 to the Consolidated Financial Statements describes the significant accounting policies and methods used in the preparation of our consolidated financial statements. We evaluate our estimates and judgments, including those described in greater detail below, on an ongoing basis. We base our estimates on historical experience and on various other factors that we believe are reasonable under the circumstances, the results of which form the basis for making judgments about the carrying value of assets and liabilities that are not readily apparent from other sources. Actual results may differ from these estimates under different assumptions or conditions.

Revenue Recognition from Collaboration

We analyze our collaboration arrangements to assess whether such arrangements, or transactions between arrangement participants, involve joint operating activities performed by parties that are both active participants in the activities and exposed to significant risks and rewards dependent on the commercial success of such activities or are more akin to a vendor-customer relationship. In making this evaluation, we consider whether the activities of the collaboration are considered to be distinct and deemed to be within the scope of the collaborative arrangement accounting standard and those that are more reflective of a vendor-customer relationship and, therefore, within the scope of the revenue with contracts with customers accounting standard. This assessment is performed throughout the life of the arrangement based on changes in the responsibilities of all parties in the arrangement.

For arrangements or transactions between arrangement participants determined to be within the scope of the contracts with customers accounting standard, we evaluate the term of the arrangement and recognize revenue when the customer obtains control of promised goods or services in a contract for an amount that reflects the consideration we expect to receive in exchange for those goods or services. For contracts with customers, we apply the following five-step model, each of which requires judgment, in order to determine this amount: (1) identification of the promised goods or services in the contract; (2) determination of whether the promised goods or services are performance obligations, including whether they are distinct in the context of the contract; (3) measurement of the transaction price, including the constraint on variable consideration; (4) allocation of the transaction price to the performance obligations; and (5) recognition of revenue when (or as) we satisfy each performance obligation.

We only apply the five-step model to contracts when it is probable we will collect the consideration we are entitled to in exchange for the goods or services we transfer to the customer. As part of the accounting for contracts with customers, we must develop assumptions that require judgment to determine the estimated relative standalone selling price (SSP) of each performance obligation identified in the contract. We then allocate the total transaction price to each performance obligation based on its SSP and recognize as revenue the amount of the transaction price that is allocated to the respective performance obligation when or as the performance obligation is satisfied.

For recognition of revenue relating to the Gilead Collaboration Agreement, we determined the transaction price and allocated it to a single combined performance obligation, the discovery, research and development services during the collaboration term. We estimated the SSP of extension fees and opt-in rights pursuant to the Gilead Collaboration Agreement using significant estimates, including forecasted revenues and costs, development timelines, discount rates, and probabilities of technical and regulatory success. We concluded none of the options in the contract are performance obligations at the outset of the arrangement as they are contingent upon option exercise, are capable of being distinct from the research and development services and are not offered at a discount to their SSP. We evaluate each performance obligation to determine if it can be satisfied at a point in time or over time, and we measure the services delivered to the customer, which we periodically review based on the progress of the related program. We recognize revenue under the Gilead Collaboration Agreement over time using a cost-based input method. Revenue related to certain performance obligations that are satisfied over time could be materially impacted as a result of changes in the estimated total research effort required to satisfy those obligations. A 10% change in the total estimated

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effort required to satisfy the single combined performance obligation related to the Gilead Collaboration Agreement would have changed the related revenue recognized during the year ended December 31, 2023 by as much as $0.5 million. The effect of any change made to an estimated input component and, therefore revenue recognized, would be recorded as a change in estimate. Such changes in estimate could have a material impact on the revenue recognized in a future period. In addition, variable consideration (including regulatory and commercial milestones) must be evaluated to determine if it is constrained and, therefore, excluded from the transaction price.

Research and Development Expense and Accruals

As part of the process of preparing our consolidated financial statements, we are required to estimate certain research and development expenses. This process involves reviewing quotations and contracts, reviewing the terms of our license agreements, communicating with our vendors and applicable personnel to identify services that have been performed on our behalf and estimating the level of service performed and the associated cost incurred for the service when we have not yet been invoiced or otherwise notified of the actual cost. The majority of our service providers invoice us monthly in arrears for services performed or when contractual milestones are met. Payments made prior to the receipt of goods or services to be used in research and development are capitalized until the goods or services are received. Such payments are evaluated for current or long-term classification based on when they will be realized or consumed. Examples of estimated amortized or accrued research and development expenses include fees to:

•

contract research organizations (CROs) and other service providers in connection with clinical studies;

•

contract manufacturing organizations (CMOs) in connection with the production of clinical trial materials; and

•

vendors in connection with nonclinical development activities.

We base our expenses related to clinical studies on our estimates of the services received and efforts expended pursuant to contracts with multiple research institutions and CROs that conduct and manage clinical studies on our behalf. The financial terms of these agreements are subject to negotiation, vary from contract to contract and may result in uneven payment flows and expense recognition. Payments under some of these contracts depend on factors such as the successful enrollment of patients and the completion of clinical trial milestones. In either amortizing or accruing service fees, we estimate the time period over which services will be performed and the level of effort to be expended in each period. If the actual timing of the performance of services or the level of effort varies from our estimate, we adjust the related prepayment or accrual accordingly. Our understanding of the status and timing of services performed relative to the actual status and timing of services performed may vary and may result in our reporting changes in estimates in any particular period. Adjustments to prior period estimates have not been material for the years ended December 31, 2023 and 2022.

We have and may continue to enter into license agreements to access and utilize certain technology. In each case, we evaluate if the license agreement results in the acquisition of an asset or a business. To date, none of our license agreements have been considered to be acquisitions of businesses. For asset acquisitions, the upfront payments to acquire such licenses, as well as any future milestone payments, are immediately recognized as research and development expense when paid, provided there is no alternative future use of the rights in other research and development projects. These license agreements may also include contingent consideration in the form of cash payments to be made for future milestone events. We assess whether such contingent consideration meets the definition of a derivative and to date we have determined that such contingent consideration are not derivatives.

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Results of Operations

Comparison of the Years Ended December 31, 2023 and 2022

Collaboration Revenue

The following table summarizes the period-over-period changes in our collaboration revenue (in thousands, except for percentages):

Year Ended December 31, $ Change % Change

Collaboration revenue for the year ended December 31, 2023 includes the recognition of $4.4 million for services performed under the Gilead Collaboration Agreement entered into in October 2023. Additionally, collaboration revenue includes the recognition of $2.7 million of deferred revenue allocated to 3733 under the BeiGene Agreement upon discontinuing development of 3733, following entering into the Gilead Collaboration, as we prioritize 4334. There was no revenue for the year ended December 31, 2022.

Research and Development Expenses

Research and development expenses consist primarily of employee-related expenses, fees paid to CROs and CMOs, lab supplies and other third-party expenses that support our research and discovery, nonclinical and clinical activities. External costs represent a significant portion of our research and development expenses, which we track on a program-by-program basis following the nomination of a development candidate. We use our employee and infrastructure resources, as well as certain third-party costs, across multiple research and development programs, and we do not specifically allocate these costs to our programs.

The following table summarizes the period-over-period changes in our research and development expenses (in thousands, except for percentages):

Year Ended December 31, $ Change % Change

External expenses:

Research and development expenses were $48.9 million for the year ended December 31, 2023 compared to $70.0 million for the year ended December 31, 2022. The $21.1 million decrease in research and development expenses was primarily driven by decreases in external expenses due to pausing further development of our CAMs as we sought partnering opportunities after the completion of the Phase 1b trial for 3733 and Phase 1a trial for 4334 and our discontinuation of the VBR and 2158 programs. We also experienced decreases in employee and contractor-related expenses of $8.1 million due to the termination of employees as part of the reorganization announced in July 2022. This was partially offset by increases in external expenses generated from the advancement of 5366 and 6250.

General and Administrative Expenses

General and administrative expenses consist primarily of salaries and other related costs for personnel in executive, finance, accounting, business development, information technology, legal and human resources functions. Other

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significant costs include facility costs not otherwise included in research and development expenses, insurance costs, legal fees relating to patents and corporate matters and fees for accounting and consulting services.

The following table summarizes the period-over-period change in our general and administrative expenses (in thousands, except for percentages):

Year Ended December 31, $ Change % Change

General and administrative expenses were $22.9 million for the year ended December 31, 2023, compared to $24.1 million for the year ended December 31, 2022. The decrease of $1.2 million in general and administrative expenses was primarily due to a $2.2 million decrease in salaries and benefits due to a decrease in headcount, largely attributable to the reorganization announced in July 2022. This was partially offset by an increase in legal expenses incurred with entering into the Gilead Collaboration.

Interest and Other Income, Net

Interest income consists of interest earned on our cash and cash equivalents and available-for-sale securities.

The following table summarizes the period-over-period changes in our interest and other income, net (in thousands, except for percentages):

Year Ended December 31, $ Change % Change

Interest and other income, net was $3.5 million for the year ended December 31, 2023, compared to $1.0 million for the year ended December 31, 2022. The increase of $2.4 million was primarily due to more interest income earned on marketable securities caused by multiple interest rate increases in 2023 and a larger portfolio balance after the receipt of $100.0 million upon entering into the Gilead Collaboration in October 2023.

Liquidity and Capital Resources

Sources of Liquidity

As a result of our significant research and development expenditures and the lack of any FDA-approved products to generate product sales revenue, we have not been profitable and have generated operating losses since we were incorporated in October 2005. We have funded our operations through December 31, 2023 principally through equity financings, raising an aggregate of $618.8 million in net proceeds, and strategic collaborations, raising an aggregate of $185.7 million through upfront payments.

Future Funding Requirements

We expect our future operating expenses to increase substantially over the coming years as we continue to advance our candidates into the clinic. We monitor our cash needs and the status of the capital markets on a continuous basis. From time to time, we opportunistically raise capital and have done so numerous times since our initial public offering by issuing equity securities. We expect to continue to raise capital when and as needed and at the time and in the manner most advantageous to us.

We expect our existing cash, cash equivalents and marketable securities will enable us to fund our operating expenses and capital expenditure requirements into the second half of 2025. We have based this estimate on assumptions that may prove to be wrong, and we may utilize our available capital resources sooner than we currently expect. Our contractual obligations include operating lease obligations totaling $2.3 million as of December 31, 2023, of which $1.2 million are short-term. We also enter into contracts in the normal course of business with CROs for clinical trials and CMOs for clinical supply manufacturing and with vendors for nonclinical research studies and other services and products for operating purposes, which generally provide for termination within 30 days of notice.

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Our future capital requirements will depend on many factors, including:

•

the scope, progress, results and costs of our ongoing drug discovery, nonclinical development, laboratory testing and clinical studies of our product candidates and any additional clinical studies we may conduct in the future;

•

our ability to raise capital despite macroeconomic and geopolitical events impacting financial markets, such as rising inflation, market volatility and risk of recession;

•

our ability to realize future potential benefits pursuant to the Gilead Collaboration and maintain the collaboration;

•

our ability to manufacture, and to contract with third parties to manufacture, adequate supplies of our product candidates for our clinical studies and any eventual commercialization;

•

the costs, timing and outcome of regulatory review of our product candidates; and

•

the costs of preparing, filing and prosecuting patent applications in the United States and abroad, maintaining and enforcing our intellectual property rights and defending intellectual property-related claims.

Identifying potential product candidates and conducting nonclinical testing and clinical studies is a time-consuming, expensive and uncertain process that takes years to complete, and we may never generate the necessary data or results required to obtain marketing approval and achieve product sales. In addition, our product candidates, if approved, may not achieve commercial success. Our commercial revenues, if any, will likely be derived from sales of medicines that we do not expect to be commercially available for years, if at all. Accordingly, we will need to continue to rely on additional financings to achieve our business objectives. Adequate additional financings may not be available to us on acceptable terms, or at all. To the extent that we raise additional capital through the sale of equity, the ownership interest of our stockholders will be diluted, and the terms of these securities may include liquidation or other preferences that adversely affect the rights of our common stockholders. Debt financing, if available, may involve agreements that include covenants limiting or restricting our ability to take specific actions, such as incurring additional debt, making capital expenditures or declaring dividends. If we are unable to raise additional funds when needed, we may be required to reduce staff, delay, scale back or discontinue our product development and clinical studies or grant rights to develop and market product candidates that we would otherwise prefer to develop and market ourselves.

Cash Flows

The following table summarizes our cash flows for the periods presented (in thousands):

Year Ended December 31,

Net (decrease) increase in cash and cash equivalents $ (32,577 ) $ 6,791

Operating Activities

Net cash provided by operating activities was $22.7 million for the year ended December 31, 2023. This was primarily due to proceeds of $90.7 million from the upfront payment under the Gilead Collaboration Agreement. This was partially offset by our net loss of $61.2 million, adjusted for $5.1 million recognized for stock-based compensation expense.

Net cash used in operating activities was $84.5 million for the year ended December 31, 2022. This was primarily due to our net loss of $93.1 million, adjusted for $6.6 million recognized for stock-based compensation expense.

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Investing Activities

Net cash used in investing activities for the year ended December 31, 2023 was $69.1 million primarily due to purchases of marketable securities, net of maturities.

Net cash provided by investing activities for the year ended December 31, 2022 was $90.6 million. This was due to proceeds of $89.2 million from sales and maturities of marketable securities, net of purchases, and proceeds of $1.5 million received in 2022 from the sale of Microbiome assets in 2021.

Financing Activities

Net cash provided by financing activities for the year ended December 31, 2023 was $13.8 million resulting from the net proceeds of $9.1 million from the sale of 1,089,472 shares of our common stock in accordance with the Gilead Equity Agreements, $4.5 million from the sale of 261,170 shares of our common stock under our "at-the-market" offering program (the 2020 ATM) and $0.1 million from the issuance of 14,453 shares of common stock under the Assembly Biosciences Amended and Restated 2018 Employee Stock Purchase Plan (2018 ESPP).

Net cash provided by financing activities for the year ended December 31, 2022 was $0.6 million resulting from the net proceeds of $0.3 million from the sale of 25,068 shares of our common stock under the 2020 ATM and $0.3 million from the issuance of 18,819 shares of common stock under the 2018 ESPP.

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Item 7A. Quantitative and Qualitative Disclosures about Market Risk

Not applicable.

Item 8. Financial Statements and Supplementary Data

(a)

Financial Statements

The financial statements required to be filed pursuant to this Item 8 are appended to this report. An index of those financial statements is found on page F-1.

(b)

Supplementary Data

Not applicable.

Item 9. Changes in and Disagreements with Accountants on Accounting and Financial Disclosure

None.

Item 9A. Controls and Procedures

Evaluation of Disclosure Controls and Procedures

We maintain a system of disclosure controls and procedures, as defined in Rule 13a-15(e) promulgated under the Securities and Exchange Act of 1934, as amended (the Exchange Act), that is designed to provide reasonable assurance that information, which is required to be disclosed in our reports filed pursuant to the Exchange Act, is accumulated and communicated to management in a timely manner. At the end of fiscal year ending December 31, 2023, we carried out an evaluation, under the supervision, and with the participation of, our management, including our Chief Executive Officer and President, who serves as our principal executive officer and principal financial officer, of the effectiveness of the design and operation of our disclosure controls and procedures pursuant to Exchange Act Rule 13a-15(b). Based upon that evaluation, our Chief Executive Officer and President concluded that our disclosure controls and procedures for the fiscal year ending as of December 31, 2023 were effective at reasonable assurance levels.

Management’s Annual Report on Internal Control over Financial Reporting

Our management is responsible for establishing and maintaining adequate internal control over financial reporting, as such term is defined in Exchange Act Rule 13a-15(f). Our internal control over financial reporting is designed to provide reasonable assurance to our management and board of directors regarding the preparation and fair presentation of published financial statements. A control system, no matter how well designed and operated, can only provide reasonable, not absolute, assurance that the objectives of the control system are met. Because of these inherent limitations, management does not expect that our internal controls over financial reporting will prevent all error and all fraud. Under the supervision and with the participation of our management, including our Chief Executive Officer and President, who serves as our principal executive officer and principal financial officer, we conducted an evaluation of the effectiveness of our internal control over financial reporting based on the framework in Internal Control-Integrated Framework issued in 2013 by the Committee of Sponsoring Organizations of the Treadway Commission. Based on our evaluation under the framework in Internal Control-Integrated Framework, our management concluded that our internal control over financial reporting was effective as of December 31, 2023.

Changes in Internal Control over Financial Reporting

There were no changes in our internal control over financial reporting in the fourth quarter of 2023 that materially affected, or are reasonably likely to materially affect, our internal control over financial reporting.

Item 9B. Other Information

Not applicable.

Item 9C. Disclosure Regarding Foreign Jurisdictions that Prevent Inspections

Not applicable.

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PART III

Item 10. Directors, Executive Officers and Corporate Governance

Except as set forth below, the information required by this item will be contained in our definitive proxy statement to be filed with the SEC in connection with the Annual Meeting of Stockholders (Proxy Statement) within 120 days after the conclusion of our fiscal year ended December 31, 2023 and is incorporated in this Annual Report on Form 10-K by reference.

Code of Ethics

Our Board has adopted a Code of Ethics for our principal executive officer and all senior financial officers and a Code of Conduct applicable to all of our employees and our directors. Both Codes are available under the “Investors—Corporate Governance” section of our website at www.assemblybio.com. If we make any substantive amendments to, or grant any waivers from, the Code of Ethics for our principal executive officer, principal financial officer, principal accounting officer, controller or persons performing similar functions, or any officer or director, we will disclose the nature of such amendment or waiver on our website or in a Current Report on Form 8-K.

Item 11. Executive Compensation

The information required by this item will be contained in the Proxy Statement and is incorporated into this Annual Report on Form 10-K by reference.

Item 12. Security Ownership of Certain Beneficial Owners and Management and Related Stockholder Matters

Except for the table regarding equity compensation plans, the information required by this item will be contained in the Proxy Statement and is incorporated into this Annual Report on Form 10-K by reference.

Securities Authorized for Issuance Under Equity Compensation Plans

The following table sets forth the indicated information as of December 31, 2023 with respect to our equity compensation plans.

(1)

The weighted average exercise price is calculated solely based on the exercise prices of the outstanding stock options and does not reflect the shares that will be issued upon the vesting of outstanding awards of restricted stock units (RSUs), which have no exercise price.

(2)

This number includes the following: 19,863 shares subject to stock options granted under the 2010 Equity Incentive Plan (2010 Plan); 211,244 shares subject to outstanding awards granted under the Assembly Biosciences, Inc. Amended and Restated 2014 Stock Incentive Plan (2014 Plan), of which 209,591 were subject

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to outstanding stock options and 1,653 were subject to outstanding RSUs; 520,707 shares subject to outstanding awards granted under the Assembly Biosciences, Inc. 2018 Stock Incentive Plan, as amended (2018 Plan), of which 429,157 were subject to outstanding stock options and 91,550 were subject to outstanding RSUs; and 38,853 options assumed by us in connection with our merger with Assembly Pharmaceuticals. This number excludes purchase rights currently accruing under the Assembly Biosciences, Inc. Amended and Restated 2018 Employee Stock Purchase Plan (2018 ESPP).

(3)

This number includes: no shares under the 2010 Plan, which has been frozen; 554 shares available for issuance under the 2014 Plan; 264,627 shares available for issuance under the 2018 Plan; and 53,687 shares reserved for issuance under the 2018 ESPP. As of March 22, 2024, assuming each participant purchases the maximum number of shares in the current offering period, no more than 12,896 shares are subject to purchase in the current offering, which ends on May 14, 2024.

(4)

This number includes 65,035 shares subject to stock options granted under the 2017 Inducement Award Plan (2017 Inducement Plan); 41,666 shares subject to stock options granted under the 2019 Inducement Award Plan (2019 Inducement Plan); and 60,725 shares subject to outstanding awards granted under the 2020 Inducement Award Plan (2020 Inducement Plan), of which 58,746 were subject to outstanding stock options and 1,979 were subject to outstanding RSUs.

(5)

This number includes: 6 shares available for issuance under the 2017 Inducement Plan, no shares under the 2019 Inducement Plan and 4 shares available for issuance under the 2020 Inducement Plan.

Our stockholder-approved equity compensation plans consist of the 2018 Plan, 2014 Plan, the 2010 Plan, stock options assumed in our merger with Assembly Pharmaceuticals and the 2018 ESPP. Effective on June 2, 2016, the 2010 Plan was frozen, and no further grants will be made under the 2010 Plan. Shares that are forfeited under the 2010 Plan on or after June 2, 2016 will become available for issuance under the 2014 Plan. An “Award” under the 2018 Plan, 2014 Plan or 2010 Plan is any right to receive our common stock consisting of non-statutory stock options, incentive stock options, stock appreciation rights, RSUs, or any other stock award.

In May 2018, our stockholders approved the 2018 ESPP and it was amended and restated in May 2021. The 2018 ESPP provides for the purchase by employees of up to an aggregate of 108,333 shares of the Company’s common stock. Eligible employees can purchase shares of our common stock at the end of a predetermined offering period at 85% of the lower of the fair market value at the beginning or end of the offering period.

Our outstanding equity compensation arrangements that have not been approved by our stockholders consist of the 2017 Inducement Plan, the 2019 Inducement Plan and the 2020 Inducement Plan. In April 2017, our board of directors adopted the 2017 Inducement Plan and reserved 66,666 shares of our common stock for issuance under the 2017 Inducement Plan. In August 2019, our board of directors adopted the 2019 Inducement Plan and reserved 41,666 shares of our common stock for issuance under the 2019 Inducement Plan. In March 2020, our board of directors adopted the 2020 Inducement Plan and reserved 66,666 shares of our common stock for issuance under the 2020 Inducement Plan. The only persons eligible to receive grants of awards under the 2017 Inducement Plan, the 2019 Inducement Plan or the 2020 Inducement Plan are individuals who satisfy the standards for inducement grants under Nasdaq Marketplace Rule 5635(c)(4) and the related guidance under Nasdaq IM 5635-1-that is, generally, a person not previously an employee or director of ours, or following a bona fide period of non-employment, as an inducement material to the individual's entering into employment with us. An “Award” is any right to receive our common stock pursuant to the Inducement Plan, consisting of nonstatutory stock options, stock appreciation rights, restricted stock awards, RSUs, or any other stock award.

Item 13. Certain Relationships and Related Party Transactions, and Director Independence

The information required by this item will be contained in the Proxy Statement and is incorporated into this Annual Report on Form 10-K by reference.

Item 14. Principal Accountant Fees and Services

The information required by this item will be contained in the Proxy Statement and is incorporated into this Annual Report on Form 10-K by reference.

49

Item 15. Exhibits, Financial Statement Schedules

(a) Exhibits. The following exhibits are filed as part of this Annual Report on Form 10-K:

4.2 Description of Securities. X

50

51

21.1 List of Subsidiaries of Assembly Biosciences, Inc. X

23.1 Consent of Independent Registered Public Accounting Firm. X

24.1 Power of Attorney (included on signature page). X

97.1 Clawback Policy. X

101.INS Inline XBRL Instance Document.

101.SCH Inline XBRL Taxonomy Extension Schema Document.

101.CAL Inline XBRL Taxonomy Extension Calculation Linkbase Document.

101.DEF Inline XBRL Taxonomy Extension Definitions Linkbase Document.

101.LAB Inline XBRL Taxonomy Extension Label Linkbase Document.

101.PRE Inline XBRL Taxonomy Extension Presentation Linkbase Document.

104 Cover Page Interactive Data File (embedded within the Inline XBRL document).

* Certain information in this exhibit has been omitted and filed separately with the Securities and Exchange Commission pursuant to a confidential treatment request.

† The schedules to this exhibit have been omitted pursuant to Item 601(a)(5) of Regulation S-K.

‡ Portions of this exhibit have been omitted pursuant to Item 601(b)(10)(iv) of Regulation S-K.

# Represents management contracts or compensatory plans or arrangements.

** The certification attached as Exhibit 32.1 that accompanies this Annual Report on Form 10-K is to be deemed furnished and shall not be deemed “filed” with the SEC and is not to be incorporated by reference into any filing of Assembly Biosciences, Inc. under the Securities Act of 1933, as amended, or the Securities Exchange Act of 1934, as amended, whether made before or after the date of this Annual Report on Form 10-K, irrespective of any general incorporation language contained in such filing.

Item 16. Form 10-K Summary

None.

52

SIGNATURES

In accordance with Section 13 or 15(d) of the Securities Exchange Act, the Registrant caused this report to be signed on its behalf by the undersigned, thereunto duly authorized.

ASSEMBLY BIOSCIENCES, INC.

Date: March 28, 2024 By: /s/ Jason A. Okazaki

Name: Jason A. Okazaki

Title: Chief Executive Officer and President

POWER OF ATTORNEY

KNOW ALL PERSONS BY THESE PRESENTS, that each person whose signature appears below constitutes and appoints Jason A. Okazaki and John O. Gunderson, jointly and severally, his or her attorneys-in-fact, each with the power of substitution, for him or her in any and all capacities, to sign any amendments to this report, and to file the same, with exhibits thereto and other documents in connection therewith with the Securities and Exchange Commission, hereby ratifying and confirming all that each of said attorneys-in-fact, or his or her substitute or substitutes may do or cause to be done by virtue hereof.

Pursuant to the requirements of the Securities Exchange Act of 1934, this report has been signed by the following persons on behalf of the registrant in the capacities and on the dates indicated.

Signature Title Date

Jason A. Okazaki (Principal Executive Officer and Principal Financial Officer)

Jeanette M. Bjorkquist (Principal Accounting Officer)

/s/ William R. Ringo, Jr. Chairman of the Board March 28, 2024

William R. Ringo, Jr.

/s/ Anthony E. Altig Director March 28, 2024

Anthony E. Altig

/s/ Tomas Cihlar, Ph.D. Director March 28, 2024

Tomas Cihlar, Ph.D.

/s/ Gina Consylman Director March 28, 2024

Gina Consylman

/s/ Robert D. Cook II Director March 28, 2024

Robert D. Cook II

/s/ Sir Michael Houghton, Ph.D. Director March 28, 2024

Sir Michael Houghton, Ph.D.

/s/ Lisa R. Johnson-Pratt, M.D. Director March 28, 2024

Lisa R. Johnson-Pratt, M.D.

/s/ Susan Mahony, Ph.D. Director March 28, 2024

Susan Mahony, Ph.D.

/s/ John G. McHutchison, A.O., M.D. Director March 28, 2024

John G. McHutchison, A.O., M.D.

53

ASSEMBLY BIOSCIENCES, INC.

FINANCIAL STATEMENTS

Page

Report of Independent Registered Public Accounting Firm (PCAOB ID: 42) F-2

Consolidated Balance Sheets as of December 31, 2023 and 2022 F-4

Notes to Consolidated Financial Statements F-8

F-1

Report of Independent Registered Public Accounting Firm

To the Stockholders and the Board of Directors of Assembly Biosciences, Inc.

Opinion on the Financial Statements

We have audited the accompanying consolidated balance sheets of Assembly Biosciences, Inc. (the Company) as of December 31, 2023 and 2022, the related consolidated statements of operations and comprehensive loss, changes in stockholders’ equity and cash flows for each of the two years in the period ended December 31, 2023, and the related notes (collectively referred to as the “consolidated financial statements”). In our opinion, the consolidated financial statements present fairly, in all material respects, the financial position of the Company at December 31, 2023 and 2022, and the results of its operations and its cash flows for each of the two years in the period ended December 31, 2023, in conformity with U.S. generally accepted accounting principles.

Basis for Opinion

These financial statements are the responsibility of the Company‘s management. Our responsibility is to express an opinion on the Company’s financial statements based on our audits. We are a public accounting firm registered with the Public Company Accounting Oversight Board (United States) (PCAOB) and are required to be independent with respect to the Company in accordance with the U.S. federal securities laws and the applicable rules and regulations of the Securities and Exchange Commission and the PCAOB.

We conducted our audits in accordance with the standards of the PCAOB. Those standards require that we plan and perform the audit to obtain reasonable assurance about whether the financial statements are free of material misstatement, whether due to error or fraud. The Company is not required to have, nor were we engaged to perform, an audit of its internal control over financial reporting. As part of our audits we are required to obtain an understanding of internal control over financial reporting but not for the purpose of expressing an opinion on the effectiveness of the Company's internal control over financial reporting. Accordingly, we express no such opinion.

Our audits included performing procedures to assess the risks of material misstatement of the financial statements, whether due to error or fraud, and performing procedures that respond to those risks. Such procedures included examining, on a test basis, evidence regarding the amounts and disclosures in the financial statements. Our audits also included evaluating the accounting principles used and significant estimates made by management, as well as evaluating the overall presentation of the financial statements. We believe that our audits provide a reasonable basis for our opinion.

Critical Audit Matter

The critical audit matter communicated below is a matter arising from the current period audit of the financial statements that was communicated or required to be communicated to the audit committee and that: (1) relates to accounts or disclosures that are material to the financial statements and (2) involved our especially challenging, subjective or complex judgments. The communication of the critical audit matter does not alter in any way our opinion on the consolidated financial statements, taken as a whole, and we are not, by communicating the critical audit matter below, providing a separate opinion on the critical audit matter or on the accounts or disclosures to which it relates.

F-2

Collaboration Agreement with Gilead Sciences, Inc.

/s/ Ernst & Young LLP

We have served as the Company’s auditor since 2015.

San Jose, California

March 28, 2024

F-3

ASSEMBLY BIOSCIENCES, INC.

CONSOLIDATED BALANCE SHEETS

(In thousands except for share amounts and par value)

December 31, December 31,

ASSETS

Current assets

Accounts receivable from collaboration 43 944

Prepaid expenses and other current assets 3,497 4,413

Property and equipment, net 385 743

Operating lease right-of-use (ROU) assets 2,339 3,195

LIABILITIES AND STOCKHOLDERS' EQUITY

Current liabilities

Accrued research and development expenses 885 3,122

Deferred revenue - short-term ($30,915 and $− to a related party) 30,915 —

Operating lease liabilities - short-term 1,220 3,364

Deferred revenue - long-term ($55,379 and $− to a related party) 55,379 2,733

Operating lease liabilities - long-term 1,122 101

Commitments and contingencies

Stockholders' equity

Accumulated other comprehensive loss (81 ) (803 )

Total liabilities and stockholders' equity $ 136,823 $ 101,794

See Accompanying Notes to the Consolidated Financial Statements

F-4

ASSEMBLY BIOSCIENCES, INC.

CONSOLIDATED STATEMENTS OF OPERATIONS AND COMPREHENSIVE LOSS

(In thousands except for share and per share amounts)

Year Ended December 31,

Collaboration revenue ($4,430 and $− from a related party) $ 7,163 $ —

Operating expenses

Other income

Interest and other income, net 3,451 1,022

Income tax expense (33 ) —

Other comprehensive loss

Unrealized gain (loss) on marketable securities 722 (384 )

Net loss per share, basic and diluted $ (13.38 ) $ (23.08 )

See Accompanying Notes to the Consolidated Financial Statements

F-5

ASSEMBLY BIOSCIENCES, INC.

CONSOLIDATED STATEMENTS OF CHANGES IN STOCKHOLDERS’ EQUITY

(In thousands except for share amounts)

Shares Amount Capital Loss Deficit Equity

Unrealized loss on marketable debt securities — — — (384 ) — (384 )

Stock-based compensation — — 6,597 — — 6,597

Issuance of common stock under ESPP 14,453 — 129 — — 129

Issuance of common stock for settlement of RSUs 43,105 — — — — —

Unrealized gain on marketable debt securities — — — 722 — 722

Stock-based compensation — — 5,121 — — 5,121

See Accompanying Notes to the Consolidated Financial Statements

F-6

ASSEMBLY BIOSCIENCES, INC.

CONSOLIDATED STATEMENTS OF CASH FLOWS

(In thousands)

Year Ended December 31,

Cash flows from operating activities

Adjustments to reconcile net loss to net cash used in operating activities:

Depreciation and amortization 450 498

Loss on disposal of property and equipment 139 —

Changes in operating assets and liabilities:

Accounts receivable from collaboration 901 (608 )

Prepaid expenses and other current assets 916 1,328

Accrued research and development expenses (2,237 ) (278 )

Operating lease liabilities (3,774 ) (3,670 )

Net cash provided by (used in) operating activities 22,743 (84,463 )

Cash flows from investing activities

Proceeds from maturities of marketable securities 65,015 88,000

Proceeds from sale of property and equipment 24 —

Purchases of property and equipment (255 ) (102 )

Proceeds from sale of marketable securities — 28,825

Proceeds from the sale of Microbiome assets — 1,500

Net cash (used in) provided by investing activities (69,138 ) 90,640