ASMB

ASSEMBLY BIOSCIENCES, INC.

NASDAQ · HEALTH CARE · PHARMACEUTICAL PREPARATIONS

20.28

−0.18 −0.88%

USD · close Oct 22

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MKT CAP $412.9MP/E 19.9DIV YIELD —FCF YIELD -9.34%REV TTM —NET INCOME −$42KNET CASH $31.9M52W 20.09 – 38.50SEC XBRL · TTM TO Invalid Date

How ASMB rewrote its risk factors

10-K ITEM 1A · FY2024 → FY2025

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Risk Factors” in this Annual Report on Form 10-K for the year ended December 31, 2025.
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 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 expect our collaboration with Gilead to be a critical part of the development, manufacture and commercialization of our product candidates. • 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. • We rely on contract resource organizations (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. • The ongoing shutdown of the U.S.
Department of Homeland Security could prevent the U.S.
Customs and Border Protection from performing normal business functions on which the operation of our business relies. • Top-line, preliminary or interim data may not accurately reflect the final results of a particular study. • 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. • If we lose key management personnel and cannot recruit and retain similarly qualified replacements, our business may materially suffer. • Our collaboration partners might delay, prevent or undermine the success of our product candidates. • We may not be successful in establishing and maintaining collaborations, which could adversely affect our ability to develop certain of our product candidates. • We rely on data provided by third parties that has not been independently. • Research, development and commercialization goals, including data releases, 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. • Competitors' developments may render our product candidates or technologies obsolete or non-competitive. • 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. • Significant disruptions of information technology systems or breaches of data security, including cybersecurity incidents, could materially and adversely affect our business. • Our ability to use our net operating loss and credit carryforwards and certain other tax attributes may be limited.
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. • The regulatory approval processes of the FDA and comparable foreign authorities are lengthy, time consuming and inherently unpredictable. • We and our third-party partners and service providers are subject to stringent privacy laws, information security laws, regulations, policies and contractual obligations related to data privacy and security, and compliance with such laws, regulations, policies and contractual obligations could result in additional costs and liabilities to us and failure to comply could adversely affect our business. • 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, other 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, exclusion or suspension from federal and state healthcare programs, contractual damages, reputational harm and diminished profits and future earnings. • We face the risk of product liability claims and might not be able to obtain insurance. • We might be exposed to liability claims associated with the use of hazardous materials and chemicals. • Our employees, independent contractors, consultants, collaborators and CROs may engage in misconduct or other improper activities, including noncompliance with regulatory standards and requirements for which we may be held responsible and which could result in significant liability for us and harm our reputation.
Risks Related to Our Intellectual Property • Our business depends on protecting our intellectual property. • We may incur substantial costs as a result of litigation or other proceedings relating to our patents and other intellectual property rights. • 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. • The cost of maintaining our patent protection globally is high and requires continuous review and compliance. • Intellectual property rights do not address all potential threats to any competitive advantage we may have.
Risks Related to Our Common Stock • The price of our common stock has in the past and may continue to fluctuate significantly. • Our 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.
Business 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 multiple clinical-stage investigational therapies, including: (1) two long-acting helicase-primase inhibitors (HPIs) for the treatment of recurrent genital herpes; (2) an orally bioavailable hepatitis delta virus (HDV) entry inhibitor; and (3) a highly potent next-generation capsid assembly modulator (CAM) designed to disrupt the replication cycle of hepatitis B virus (HBV) at several key points.
Our pipeline also includes a novel, oral broad-spectrum non-nucleoside polymerase inhibitor (NNPI) for the treatment of transplant-related herpesviruses, which is currently undergoing studies to enable a regulatory filing, and we have additional research programs against multiple antiviral targets.
In December 2025, pursuant to our collaboration (Gilead Collaboration) with Gilead Sciences, Inc.
(Gilead), Gilead exercised its option to license our HPI program for the treatment of recurrent genital herpes, including our long-acting investigational candidates ABI-1179 (1179) and ABI-5366 (5366).
For additional information regarding Gilead’s exercise of its option, see “Collaboration and License Agreement—Gilead Sciences, Inc.—Option Exercise.” Our Strategy Our current business strategy focuses on applying our deep research and development expertise in virology to discover, develop and advance next-generation therapeutics to patients in areas of high unmet medical need with significant market opportunities to market.
We continue to rapidly advance our portfolio toward near-term clinical readouts, highlighted by the following on-going and future activities by doing the following: • Recurrent Genital Herpes (HSV-1, HSV-2) – Transitioning our HPI program, including 5366 and 1179 to Gilead and, upon receiving a clinical development plan and budget from Gilead, deciding whether to opt in to the Profit-Share (as defined below under the heading “Collaboration and License Agreement—Gilead Sciences, Inc.—Option Exercise”). • HDV – Completing Phase 2 preparation activities and studies of ABI-6250 (6250), with Phase 2 initiation expected in the fourth quarter of 2026. • HBV – Evaluating partnering opportunities for ABI-4334 (4334), for which we have initiated a structured process to find potential partners to further advance the program. • Transplant-Associated Herpesviruses – Advancing ABI-7272 (7272), our oral broad-spectrum NNPI for the treatment of transplant-associated herpesviruses through nonclinical studies to enable a regulatory filing. • Research and Discovery – Continuing to leverage our research team's expertise to identify and nominate new viral targets and novel compounds to address significant unmet medical needs.
We have recruited an accomplished leadership team and research and development organization, with a collective team track record of over 15 approved drugs across multiple viral diseases.
In addition, our collaboration with Gilead also brings us an industry-leading partner and brings together the teams’ expertise in virology and provides an established partner for late-stage development and commercialization.
For additional information regarding the Gilead Collaboration, see “Collaboration and License Agreements—Gilead Sciences, Inc.” Our Clinical Programs and Regulatory Filing-Enabling Program 2025 was a pivotal year for us, as we reported positive data readouts for 5366, 1179, 4334 and 6250 as follows: • February 2025: o 1179 – Positive Phase 1a interim results in the Phase 1a/b study • June 2025: o 4334 – Positive Phase 1b topline results • August 2025: o 5366 – Positive Phase 1b interim results from the weekly dosing cohorts in the Phase 1a/b study o 6250 – Positive Phase 1a interim results • December 2025: o 1179 – Positive Phase 1b interim results in the Phase 1a/b study o 5366 – Positive Phase 1b interim results from the monthly dosing cohorts in the Phase 1a/b study In addition, during December 2024, we identified a development candidate, ABI-7423 (7423), in our broad-spectrum NNPI program targeting transplant-associated herpesviruses. 7423 is a prodrug of the parent molecule 7272, and in October 2025, we transitioned our development from 7423 to 7272. 7272 is currently in regulatory filing enabling studies.
Genital herpes recurrence can cause painful genital lesions that can lead to increased transmission and debilitate individuals, and symptoms may become more serious with additional episodes.
Immunocompromised individuals may experience more severe and prolonged symptoms due to increased recurrence rates.
Most people with initial symptomatic genital herpes who are infected with HSV-2 have frequent recurrences, generally between three and 15 per year, impacting over four million people in the United States and France, Germany, Italy and Spain (collectively, the EU4) and the United Kingdom (UK).
In addition, nucleoside analogs also carry a high pill burden as a lifelong daily treatment, with doses ranging from one to three times daily.
There is also high treatment variability among those taking nucleoside analogs, as many seeking care may not consistently receive suppressive therapy.
To reach that goal, we discovered and began the clinical development of a novel, potent, long-acting HPI for recurrent genital herpes, 5366, which demonstrated low nanomolar potency in vitro against both HSV-1 and HSV-2 clinical isolates and a favorable nonclinical safety profile in the U.S.
Food and Drug Administration's (FDA) Good Laboratory Practice (GLP) toxicology studies.
In addition, we began development of a second novel, potent, long-acting HPI for genital herpes, 1179, which was in-licensed to us as part of our collaboration with Gilead.
As Gilead has exercised its option to exclusively license our HPI program, including 5366 and 1179, development will be in Gilead’s sole control following completion of the Phase 1a/b studies of 5366 and 1179, which we are managing until they are complete.
For additional information regarding the option exercise, see “Collaboration and License Agreements—Gilead Sciences, Inc.—Option Exercise.” During the first quarter of 2024, we filed a Clinical Trial Application (CTA) to support initiation of a Phase 1a/b clinical study for 5366, which was approved in April 2024, and we dosed our first participant in the Phase 1a portion of this study during the second quarter of 2024.
In September 2024, we announced positive interim data for the Phase 1a portion of the 5366 study and complete data was presented at the STI & HIV 2025 World Congress in July 2025.
Results exceeded our objectives for this Phase 1a study and supported 5366’s progression into Phase 1b, which we initiated during the third quarter of 2024.
In the Phase 1a cohorts, 5366 was well-tolerated with a favorable safety profile, with exposures of up to 99 days.
We reported interim data from the Phase 1b portion of the 5366 study in August 2025, focused on two different oral doses of 5366 administered on a once-weekly basis.
For the powered antiviral endpoint, HSV-2 shedding rate, highly potent antiviral activity was observed with a 94% reduction compared to placebo (p<0.01) over the 29-day evaluation period in the cohort evaluating a 350 mg weekly dose.
This reduction exceeded our target for the study of an 80-85% reduction in the rate of HSV-2 shedding.
For a secondary clinical endpoint of genital lesion rate, a 94% reduction compared to placebo (p<0.01) was observed with the 350 mg weekly dose.
The rate of genital swabs with high viral load (i.e., >10 4 copies/mL HSV DNA), a potential surrogate for HSV-2 transmission and a secondary endpoint, was reduced by 98% compared to placebo (p<0.05) in this cohort.
We reported additional interim data from the Phase 1b portion of the 5366 study in December 2025, which included data from a monthly oral dosing regimen.
In the 5366 monthly dose cohort, potent antiviral activity was observed, with a 76% reduction in HSV-2 shedding rate compared to placebo (p<0.01) over the 29-day evaluation period.
The majority of positive swabs (89%) were collected in the last two weeks of the evaluation period when drug levels were declining.

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Risk Factors.” 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 and regularly attends cybersecurity conferences and actively implements new technologies to keep our systems up to date and secure, 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.
P roperties We lease office space for corporate and administrative functions and laboratory space in South San Francisco, California under a sublease that expires in September 2029.
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.
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.
Mine Saf ety Disclosures Not applicable.
Market for Registrant’s Common Equity, Related Sto ckholder 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 14, 2025, there were 49 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 2024.
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 adjusted to reflect the Reverse Stock Split.
Management’s Discussion and Analysis o f 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 multiple clinical-stage investigational therapies, including: (1) two helicase-primase inhibitors (HPI) targeting recurrent genital herpes; (2) an orally bioavailable hepatitis delta virus (HDV) entry inhibitor; and (3) a highly potent next-generation capsid assembly modulator (CAM) designed to disrupt the replication cycle of hepatitis B virus (HBV) at several key points.
Our pipeline also includes a novel, oral broad-spectrum non-nucleoside polymerase inhibitor (NNPI) targeting transplant-related herpesviruses, which is currently undergoing studies to enable a regulatory filing, and we have additional research programs against multiple antiviral targets.
Our Clinical Programs and Regulatory Filing-Enabling Program Since the beginning of 2024, we have initiated: (1) both the Phase 1a and Phase 1b portions of a Phase 1a/b study of 5366, long-acting HPI for recurrent genital herpes; (2) the Phase 1a portion of a Phase 1a/b study of 1179, also a long-acting HPI for recurrent genital herpes; (3) a Phase 1a study of 6250, an orally bioavailable HDV entry inhibitor; and (4) a Phase 1b study of 4334, a highly potent, next-generation CAM for chronic HBV infection.
We expect to initiate the Phase 1b portion of the Phase 1a/b study of 1179 in the first half of 2025.
We announced interim results from the Phase 1a portion of the 5366 study in September 2024, interim results from the Phase 1b study of 4334 in December 2024 and interim results from the Phase 1a portion of the 1179 study in February 2025.
In addition, during December 2024, we identified a development candidate, 7423, in our broad-spectrum NNPI program targeting transplant-associated herpesviruses.
Genital herpes recurrence can cause painful genital lesions that can lead to increased transmission and debilitate patients, and symptoms may become more serious with additional episodes.
Immunocompromised patients may experience more severe and prolonged symptoms due to increased recurrence rates.
Most people with initial symptomatic genital herpes who are infected with HSV-2 have frequent recurrences, generally between three and 15 per year, including over four million people in the United States and France, Germany, Italy and Spain (collectively, the EU4) and the United Kingdom (UK).
To reach that goal, we discovered and are developing a novel, potent, long-acting HPI for recurrent genital herpes, 5366, which demonstrated low nanomolar potency in vitro against both HSV-1 and HSV-2 clinical isolates and a favorable nonclinical safety profile in the U.S.
Food and Drug Administration's (FDA) Good Laboratory Practice (GLP) toxicology studies, with high safety margins and minimal potential for off-target effects.
In addition, we are developing a second novel, potent, long-acting HPI for genital herpes, 1179, which was in-licensed to us as part of our collaboration with Gilead.
During the first quarter of 2024, we filed a Clinical Trial Application (CTA) to support initiation of a Phase 1a/b clinical study for 5366, which was approved in April 2024, and we dosed our first participant in the Phase 1a portion of this study during the second quarter of 2024.
In September 2024, we announced positive interim data for the Phase 1a portion of the 5366 study.
Interim results exceeded our objectives for this Phase 1a study and support 5366’s progression into Phase 1b, which we initiated during the third quarter of 2024.
We plan to explore both once-weekly and once-monthly oral dosing regimens in the Part B (Phase 1b) portion of the study.
In the Part A cohorts, 5366 has been well-tolerated with a favorable safety profile observed with exposure of up to 70 days.

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Sentence-level comparison of Item 1A in the two most recent 10-Ks (FY2024 ↗, FY2025 ↗). A reworded sentence counts as one dropped and one added, so heavy edits read as low “kept”. Headings and page furniture are stripped; nothing is summarised by a model.

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