10-K
UNITED STATES
SECURITIES AND EXCHANGE COMMISSION
Washington, D.C. 20549
FORM 10-K
(Mark One)
☒ANNUAL REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934
For the fiscal year ended December 31, 2025
OR
☐TRANSITION REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934
For the transition period from ___________to___________
Commission file number: 001-39438
Disc Medicine, Inc.
(Exact name of registrant as specified in its charter)
321 Arsenal Street, Suite 101Watertown, Massachusetts 02472
(Address of principal executive offices) (Zip Code)
Registrant’s telephone number, including area code: (617) 674-9274
Securities registered pursuant to Section 12(b) of the Act:
Title of each class TradingSymbol(s) Name of each exchangeon which registered
Common Stock, $0.0001 Par Value IRON The Nasdaq Global Market
Securities registered pursuant to Section 12(g) of the Act:
None
Indicate by check mark if the registrant is a well-known seasoned issuer, as defined in Rule 405 of the Securities Act. Yes☒ No ☐
Indicate by check mark if the registrant is not required to file reports pursuant to Section 13 or Section 15(d) of the Act. Yes ☐No☒
Indicate by check mark whether the registrant (1) has filed all reports required to be filed by Section 13 or 15(d) of the Securities Exchange Act of 1934 during the preceding 12 months (or for such shorter period that the registrant was required to file such reports), and (2) has been subject to such filing requirements for the past 90 days. Yes☒ No ☐
Indicate by check mark whether the registrant has submitted electronically every Interactive Data File required to be submitted pursuant to Rule 405 of Regulation S-T (§232.405 of this chapter) during the preceding 12 months (or for such shorter period that the registrant was required to submit such files). Yes☒ No ☐
Indicate by check mark whether the registrant is a large accelerated filer, an accelerated filer, a non-accelerated filer, a smaller reporting company, or an emerging growth company. See the definitions of “large accelerated filer,” “accelerated filer,” “smaller reporting company,” and “emerging growth company” in Rule 12b-2 of the Exchange Act.
Large accelerated filer ☒ Accelerated filer ☐
Non-accelerated filer ☐ Smaller reporting company ☐
Emerging growth company ☐
If an emerging growth company, indicate by check mark if the registrant has elected not to use the extended transition period for complying with any new or revised financial accounting standards provided pursuant to Section 13(a) of the Exchange Act. ☐
Indicate by check mark whether the registrant has filed a report on and attestation to its management’s assessment of the effectiveness of its internal control over financial reporting under Section 404(b) of the Sarbanes-Oxley Act (15 U.S.C. 7262(b)) by the registered public accounting firm that prepared or issued its audit report. ☒
If securities are registered pursuant to Section 12(b) of the Act, indicate by check mark whether the financial statements of the registrant included in the filing reflect the correction of an error to previously issued financial statements. ☐
Indicate by check mark whether any of those error corrections are restatements that required a recovery analysis of incentive-based compensation received by any of the registrant’s executive officers during the relevant recovery period pursuant to §240.10D-1(b). ☐
Indicate by check mark whether the registrant is a shell company (as defined in Rule 12b-2 of the Exchange Act). Yes ☐ No ☒
The aggregate market value of Common Stock held by non-affiliates of the registrant computed by reference to the price of the registrant’s Common Stock as of June 30, 2025, the last business day of the registrant’s most recently completed second fiscal quarter, was approximately $1.4 billion (based on the last reported sale price on the Nasdaq Global Market as of such date).
As of February 19, 2026, there were 38,160,065 shares of the registrant’s Common Stock, $0.0001 par value per share, outstanding.
DOCUMENTS INCORPORATED BY REFERENCE
Portions of the registrant’s Proxy Statement for its 2026 Annual Meeting of Stockholders, which the registrant intends to file with the Securities and Exchange Commission not later than 120 days after the registrant’s fiscal year ended December 31, 2025, are incorporated by reference into Part III of this Annual Report on Form 10-K.
Disc Medicine, Inc.
Index
Page
PART I
Item 1. Business 1
Item 1A. Risk Factors 46
Item 1B. Unresolved Staff Comments 98
Item 1C. Cybersecurity 98
Item 2. Properties 98
Item 3. Legal Proceedings 99
Item 4. Mine Safety Disclosures 99
PART II
Item 7A. Quantitative and Qualitative Disclosures About Market Risk 111
Item 8. Financial Statements and Supplementary Data 112
Item 9A. Controls and Procedures 142
Item 9B. Other Information 144
PART III
Item 10. Directors, Executive Officers and Corporate Governance 145
Item 11. Executive Compensation 145
Item 14. Principal Accounting Fees and Services 145
PART IV
Item 15. Exhibits, Financial Statement Schedules 146
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FORWARD-LOOKING STATEMENTS
This Annual Report on Form 10-K of Disc Medicine, Inc., or the Company, contains or incorporates statements that constitute forward-looking statements within the meaning of the federal securities laws. Our forward-looking statements include, but are not limited to, statements regarding our or our management team’s expectations, hopes, beliefs, intentions or strategies regarding the future. In addition, any statements that refer to projections, forecasts or other characterizations of future events or circumstances, including any underlying assumptions, are forward-looking statements. The words “anticipate,” “believe,” “contemplate,” “continue,” “could,” “estimate,” “expect,” “intends,” “may,” “might,” “plan,” “possible,” “potential,” “predict,” “project,” “should,” “will,” “would” and similar expressions may identify forward-looking statements, but the absence of these words does not mean that a statement is not forward-looking. Forward-looking statements in this Annual Report on Form 10-K may include, for example, statements about:
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the initiation, timing, progress, results, and cost of our research and development programs and our current and future preclinical studies and clinical trials, including statements regarding the timing of initiation and completion of studies or trials and related preparatory work, the period during which the results of the trials will become available, and our research and development programs;
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our ability to efficiently discover and develop product candidates;
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our ability to successfully manufacture our drug substances and product candidates for preclinical use, for clinical trials and on a larger scale for commercial use, if approved;
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our ability to obtain funding for our operations necessary to further develop and, if approved, commercialize our product candidates;
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our ability to obtain and maintain regulatory approval of bitopertin and any of our other product candidates;
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our ability to commercialize our products, if approved;
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the pricing and reimbursement of our product candidates, if approved;
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the implementation of our business model, and strategic plans for our business and product candidates;
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the scope of protection we are able to establish and maintain for intellectual property rights covering our product candidates;
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estimates of our future expenses, revenues, capital requirements, and our needs for additional financing;
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the potential benefits of strategic collaboration agreements, our ability to enter into strategic collaborations or arrangements, and our ability to attract collaborators with development, regulatory and commercialization expertise;
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future agreements with third parties in connection with the commercialization of our product candidates, if approved;
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the size and growth potential of the markets for our product candidates, and our ability to serve those markets;
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our financial performance;
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the rate and degree of market acceptance of our product candidates;
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regulatory developments in the United States and foreign countries;
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our ability to contract with third-party suppliers and manufacturers and their ability to perform adequately;
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our ability to produce our products or product candidates with advantages in turnaround times or manufacturing cost;
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the success of competing therapies that are or may become available;
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our ability to attract and retain key scientific or management personnel;
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the impact of laws and regulations;
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developments relating to our competitors and our industry;
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the impact of global economic and political developments on our business, including rising inflation and capital market disruptions, geopolitical conflicts, economic sanctions and economic slowdowns or recessions that may result from such developments which could harm our research and development efforts as well as the value of our common stock and our ability to access capital markets; and
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other risks and uncertainties, including those listed under the caption “Risk Factors.”
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These forward-looking statements are based on information available to us at the time of this Annual Report on Form 10-K and current expectations, forecasts and assumptions, and involve a number of judgments, risks and uncertainties. Accordingly, forward-looking statements should not be relied upon as representing our views as of any subsequent date, and we do not undertake any obligation to update forward-looking statements to reflect events or circumstances after the date they were made, whether as a result of new information, future events or otherwise, except as may be required under applicable securities laws.
The outcome of the events described in these forward-looking statements is subject to known and unknown risks, uncertainties, and other factors. As a result of a number of known and unknown risks and uncertainties, our actual results or performance may be materially different from those expressed or implied by these forward-looking statements. Factors that could cause actual results to differ include, but are not limited to, those discussed in the section titled “Risk Factors” included within Item 1A of this Annual Report on Form 10-K.
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RISK FACTOR SUMMARY
Below is a summary of the principal factors that make an investment in our common stock speculative or risky. This summary does not address all of the risks that we face. Additional discussion of the risks summarized in this risk factor summary and other risks that we believe are material to our investors can be found below under the heading “Item 1A. Risk Factors” and should be carefully considered, together with other information in this Annual Report on Form 10-K and our other filings with the Securities and Exchange Commission, or SEC, before making an investment decision regarding our common stock.
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Our limited operating history may make it difficult for you to evaluate the success of our business to date and to assess our future viability.
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We have incurred significant net losses since our inception and anticipate that we will continue to incur losses for the foreseeable future.
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We have no products approved for commercial sale and have not generated any revenue from product sales.
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Our existing and any future indebtedness could adversely affect our ability to operate our business.
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We may need to raise substantial additional funding. If we are unable to raise capital when needed or on terms acceptable to us, we may be forced to delay, reduce, or eliminate some of our product development programs or commercialization efforts.
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We have not yet progressed any product candidates through a Phase 3 clinical trial and may be unable to successfully complete any additional clinical trials for any product candidates we develop. Certain of our programs are still in preclinical development and may never advance to clinical development.
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Our programs are focused on the development of therapeutics for patients with hematologic diseases, which is a rapidly evolving area of science, and the approach we are taking to discover and develop product candidates is novel and may never lead to approved or marketable products.
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Because we are developing some of our product candidates for the treatment of diseases in which there is little clinical experience and, in some cases, using new endpoints or methodologies, the FDA or other regulatory authorities may not consider the endpoints of our clinical trials to predict or provide clinically meaningful results.
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Interim, top-line, initial and preliminary data from our clinical trials that we announce or publish from time to time may change as more patient data become available and are subject to confirmation, audit, and verification procedures that could result in material changes in the final data.
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If we experience delays or difficulties in the enrollment of patients in clinical trials, our receipt of necessary regulatory approvals could be delayed or prevented.
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Results from early preclinical studies and clinical trials of our programs and product candidates are not necessarily predictive of the results of later preclinical studies and clinical trials of our programs and product candidates. If we cannot replicate the results from earlier preclinical studies and clinical trials of our programs and product candidates in our later preclinical studies and clinical trials, we may be unable to successfully develop, obtain regulatory approval for and commercialize our product candidates.
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Our clinical trials or those of our future collaborators may reveal significant adverse events not seen in prior preclinical studies or clinical trials and may result in a safety profile that could inhibit regulatory approval or market acceptance of any of our product candidates.
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Some of our product candidates modulate pathways for which there are currently no approved or effective therapies, which may result in greater research and development expenses, regulatory issues that could delay or prevent approval, or discovery of unknown or unanticipated adverse effects on safety or efficacy.
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We have conducted and are currently conducting clinical trials for bitopertin, and may in the future conduct additional clinical trials of our product candidates, outside the United States, and the FDA and comparable foreign regulatory authorities may not accept data from such trials.
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If we are not able to obtain, or if there are delays in obtaining, required regulatory approvals for any of our product candidates, we will not be able to commercialize, or will be delayed in commercializing, such product candidates, and our ability to generate revenue will be materially impaired.
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We face substantial competition, which may result in others discovering, developing, or commercializing products before or more successfully than we do.
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If the market opportunities for our product candidates are smaller than we estimate or if any regulatory approval that we obtain is based on a narrower definition of the patient population, our revenue and ability to achieve profitability could be materially adversely affected.
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If our current product candidates or any future product candidates do not achieve broad market acceptance, the revenue that we generate from our sales may be limited, and we may never become profitable.
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We rely on third parties to conduct our clinical trials for our product candidates, as well as potential investigator-sponsored clinical trials of our product candidates. If these third parties do not successfully carry out their contractual duties, comply with regulatory requirements, or meet expected deadlines, we may not be able to obtain regulatory approval for or commercialize our product candidates and our business could be substantially harmed.
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We might not realize the anticipated benefits of our current collaborations with Mabwell or NIH, or any other collaborations we enter into in the future.
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We contract with third parties for the manufacture of our product candidates for preclinical development and clinical testing, and expect to continue to do so for commercialization. This reliance on third parties increases the risk that we will not have sufficient quantities of our product candidates or products or such quantities at an acceptable cost, which could delay, prevent, or impair our development or commercialization efforts.
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If we are unable to obtain and maintain patent and other intellectual property protection for our technology and product candidates, or if the scope of the intellectual property protection obtained is not sufficiently broad, our competitors could develop and commercialize technology and drugs similar or identical to ours, and our ability to successfully commercialize our technology and drugs may be impaired, and we may not be able to compete effectively in our market.
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We may not obtain licenses or sublicenses to intellectual property rights in all markets on equally or sufficiently favorable terms with third parties.
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If we fail to comply with our obligations in any agreements under which we may license intellectual property rights from third parties or otherwise experience disruptions to our business relationships with our licensors, we could lose license rights that are important to our business.
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Intellectual property rights do not guarantee commercial success of current or future product candidates or other business activities. Numerous factors may limit any potential competitive advantage provided by our intellectual property rights.
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Obtaining and maintaining regulatory approval of our product candidates in one jurisdiction does not mean that we will be successful in obtaining regulatory approval of our product candidates in other jurisdictions.
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We received a Commissioner’s National Priority Voucher for bitopertin but the accelerated timeline for review of our NDA submission for bitopertin in EPP and XLP by the FDA did not result in an approval and it is unclear what, if any, benefits this voucher may provide in the future.
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Inadequate funding for the NIH, CMS, FDA, the SEC and other government agencies, including from government shut downs, or other disruptions to these agencies’ operations, including significant leadership, personnel, or policy changes, could prevent new products and services from being developed or commercialized in a timely manner or otherwise prevent those agencies from performing normal business functions on which the operation of our business may rely, which could negatively impact our business.
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Our future success depends on our ability to retain key executives and experienced scientists and to attract, retain, and motivate qualified personnel.
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Adverse developments affecting the financial services industry, such as actual events or concerns involving liquidity, defaults, or non-performance by financial institutions or transactional counterparties, could adversely affect the Company’s current and projected business operations and its financial condition and results of operations.
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Significant political, trade or regulatory developments, unfavorable global economic conditions, and other circumstances beyond our control, could have a material adverse effect on our business, financial condition or results of operations.
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The market price of our common stock has been, and may continue to be, volatile.
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We have incurred and will continue to incur increased costs and increased demands upon management as a result of complying with the laws and regulations affecting public companies.
This section contains forward-looking statements. You should refer to the explanation of the qualifications and limitations on forward-looking statements beginning on page ii.
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PART I
Except where the context otherwise requires or where otherwise indicated, the terms “Disc,” “we,” “us,” “our,” “our company,” “the company,” and “our business” refer to Disc Medicine, Inc. and its consolidated subsidiaries.
ITEM 1.BUSINESS
Overview
We are a clinical-stage biopharmaceutical company focused on the discovery, development, and commercialization of novel treatments for patients suffering from serious hematologic diseases. We have assembled a portfolio of clinical and preclinical product candidates that aim to modify fundamental biological pathways associated with the formation and function of red blood cells, specifically heme biosynthesis and iron homeostasis. Our current pipeline includes bitopertin for the treatment of erythropoietic porphyrias, or EPs, including erythropoietic protoporphyria, or EPP, and X-linked protoporphyria, or XLP; DISC-0974 for the treatment of anemia of myelofibrosis, or MF, and anemia of inflammatory bowel disease, or IBD; and DISC-3405 for the treatment of polycythemia vera, or PV, sickle cell disease, or SCD, and other hematologic disorders. In addition, our preclinical programs include DISC-0998 for the treatment of anemia associated with inflammatory diseases. Our approach to product candidate development leverages well-understood molecular mechanisms that have been validated in humans. We believe that each of our product candidates, if approved, has the potential to improve the lives of patients suffering from hematologic diseases.
Heme Biosynthesis: Bitopertin
Bitopertin is the lead product candidate in our heme biosynthesis modulation portfolio. Bitopertin was previously evaluated by F. Hoffmann-La Roche Ltd and Hoffmann-La Roche Inc., or collectively, Roche, in a comprehensive clinical program in over 4,000 individuals in other indications which demonstrated the activity of bitopertin as a glycine transporter 1, or GlyT1, inhibitor and its effect on heme biosynthesis. We are initially developing bitopertin for the treatment of EPs, including EPP and XLP, which are part of a group of severe diseases, known as porphyrias, caused by defects in the heme biosynthesis pathway that cause an accumulation of toxic metabolites referred to as porphyrins, resulting in skin hypersensitivity to sunlight and some types of artificial light.
We have completed two Phase 2 clinical trials of bitopertin: BEACON, an open-label, parallel-dose clinical trial in EPP and XLP patients conducted at sites in Australia, and AURORA, a randomized, double-blind, placebo-controlled clinical trial in EPP patients conducted at sites in the United States. In both trials, bitopertin significantly reduced the toxic metabolite, protoporphyrin IX, or PPIX, and was associated with improvements in measures of time spent in sunlight and quality of life. In addition, bitopertin was generally well-tolerated. All participants in AURORA and BEACON were eligible to participate in HELIOS, an ongoing open-label, long-term extension study of bitopertin in EPP and XLP patients. Interim data from HELIOS, presented in June 2025, demonstrated that longer term treatment of bitopertin was associated with sustained reductions in PPIX, as well as improvements in quality of life and liver biomarkers. In our end-of-Phase 2 meeting in September 2024, the U.S. Food & Drug Administration, or the FDA, agreed with the potential for reduction of PPIX to serve as a surrogate endpoint to support a potential accelerated approval of bitopertin in EPP and XLP. In our Type C meeting in December 2024, we aligned with the FDA on the design of APOLLO, a Phase 3, randomized, double-blind, placebo-controlled, clinical trial of bitopertin in EPP and XLP patients that in the setting of an accelerated approval would serve as a post-marketing confirmatory trial. We initiated the APOLLO trial in May 2025 and in September 2025 we submitted a New Drug Application, or NDA, for accelerated approval of bitopertin in EPP and XLP in the United States based on our existing data. In October 2025, we were awarded a Commissioner’s National Priority Voucher, or CNPV, from the FDA for bitopertin in EPP and XLP. The CNPV program, announced in June 2025, is designed to accelerate the development and review of certain drugs aligned with US national health priorities. The FDA accepted our NDA for review in November 2025 and in February 2026 issued a complete response letter, or CRL. Although the FDA agreed that clinical data from AURORA and BEACON provided sufficient evidence that bitopertin significantly lowers whole blood metal-free PPIX, the FDA concluded that the trials did not show evidence of association between percent change in PPIX and sunlight exposure-based endpoints as measured in the trials. As such, the FDA determined that there is uncertainty regarding whether bitopertin’s effect on PPIX is reasonably likely to predict clinical benefit, despite the strong mechanistic and biological plausibility supporting the use of the PPIX biomarker in protoporphyria. The FDA indicated that results of the ongoing APOLLO trial could serve as evidence to support a potential traditional approval, and we plan to request a Type A meeting to review our approach with the FDA. We expect to report topline data from APOLLO in the fourth quarter of 2026, following which we plan to submit a response to the CRL.
Our APOLLO clinical trial is also intended to serve as a registrational trial with respect to any potential future marketing applications for bitopertin in EPP and XLP outside the United States. We continue to evaluate potential additional trials of bitopertin in other indications.
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Iron Homeostasis: DISC-0974 and DISC-3405
DISC-0974 is the lead product candidate in our iron homeostasis portfolio and was licensed from AbbVie Deutschland GmbH & Co. KG, or AbbVie. DISC-0974 is designed to suppress hepcidin production and increase serum iron levels. We completed a Phase 1 clinical trial in healthy volunteers in the United States in June 2022, with results showing an acceptable tolerability profile and evidence of target engagement, iron mobilization and augmented erythropoiesis. We initiated a Phase 1b/2 clinical trial in June 2022 in patients with anemia of MF, with results from the Phase 1b portion of this clinical trial showing substantial and sustained reductions in hepcidin levels and increases in iron alongside strong hematologic responses across patient types and an acceptable tolerability profile. We initiated RALLY-MF, the open-label Phase 2 portion of this clinical trial, in December 2024 and reported initial data from this Phase 2 trial in December 2025, with results demonstrating meaningful overall anemia responses across all patient subgroups, regardless of baseline transfusion status and independent of concomitant Janus Kinase, or JAK, inhibitor therapy use. Topline data from this trial is expected in the second half of 2026, which, if positive, is expected to support discussions with regulatory agencies on the potential regulatory path for DISC-0974 in anemia of MF. We initiated a Phase 2 clinical trial of DISC-0974 in patients with IBD and anemia in the first quarter of 2026, and we are planning exploratory studies in additional patient populations with anemia of chronic disease. We are also developing a preclinical anti-hemojuvelin, or HJV, monoclonal antibody, DISC-0998, which also targets hepcidin suppression and was licensed from AbbVie. DISC-0998 is designed to increase serum iron levels and has an extended serum half-life as compared to DISC-0974. We believe this profile may be desirable in certain subsets of patients with anemia associated with inflammatory diseases.
In addition, we are developing DISC-3405, a monoclonal antibody against Transmembrane Serine Protease 6, or TMPRSS6, that we licensed from Mabwell Therapeutics, Inc., or Mabwell. DISC-3405 is part of our iron homeostasis portfolio and is designed to induce hepcidin production and reduce serum iron levels. We initiated a Phase 1 clinical trial of DISC-3405 in healthy adult volunteers in October 2023 and presented interim data from the single-ascending dose, or SAD, portion of this clinical trial in June 2024. We presented data from the multiple ascending dose, or MAD, portion of this clinical trial in December 2024, and presented updated data from both the SAD and MAD portions of this clinical trial in June 2025, with results showing an acceptable tolerability profile and evidence of target engagement, including dose-related increases in serum hepcidin and corresponding reductions in serum iron across all dose levels. We are developing DISC-3405 for the treatment of PV, SCD, and other hematologic disorders. We initiated RESTORE-PV, an open-label Phase 2 clinical trial of DISC-3405 in patients with PV, in the first half of 2025, with initial data expected in the second half of 2026. We also initiated a Phase 1b, open-label clinical trial of DISC-3405 in patients with SCD in October 2025, with initial data expected in the second half of 2026, and plan to explore the role of therapeutic iron restriction in other indications.
Our Approach
Our goal is to continue to build and advance a portfolio of product candidates that focus on fundamental biological pathways associated with the formation and function of red blood cells. Red blood cells have the essential role of carrying oxygen via hemoglobin to all tissues and organs in the body. The biological processes that are required to maintain normal levels of functional red blood cells are complex, and a variety of congenital and acquired diseases occur due to imbalances or deficiencies in red blood cell formation and function. Two key components needed to support the formation and function of red blood cells are heme and iron. Heme is an essential part of red blood cells, and when complexed into the hemoglobin protein, it performs the vital function of transporting oxygen throughout the body. Iron is a key component of heme, and therefore both iron and heme are required for erythropoiesis, the biological process by which precursor cells in the bone marrow mature to become red blood cells. Based on results in animal models and preclinical and clinical data, we believe that our product candidate portfolio, by targeting fundamental pathways in red blood cell biology, has the potential to address a range of hematologic diseases in which modification of iron and heme plays a critical function.
We are focused on therapeutic approaches that modulate heme and iron to address diseases of heme biosynthesis and red blood cell production, and we target therapeutic mechanisms that have been validated in humans, through evidence from either human genetics or third-party clinical trials. For example, our lead program, bitopertin, has been evaluated in over 4,000 individuals and demonstrated suppression of heme biosynthesis in multiple clinical trials conducted by Roche. The targets of our iron homeostasis portfolio, HJV and TMPRSS6, have both been genetically validated in humans and shown to have a role in the regulation of hepcidin and iron homeostasis. For example, individuals with inherited loss of the HJV gene exhibit low levels of hepcidin and individuals with inherited loss of the TMPRSS6 gene exhibit elevated levels of hepcidin.
By focusing on fundamental red blood cell biology that is validated in humans, we believe that our product candidates are more likely to exhibit well-defined biological effects in clinical trials and have the potential for broad applicability across a wide range of hematologic diseases. Our current pipeline is focused on the following three approaches:
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Modulating the heme biosynthesis pathway, which is anticipated to be useful in diseases caused by excesses in toxic heme pathway metabolites, e.g., EPs;
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Increasing iron availability to red blood cell precursors, which is anticipated to have direct effects on increasing red blood cell production to correct anemia in diseases of iron restriction, e.g., anemia associated with inflammatory diseases; and
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Decreasing iron availability, which is anticipated to lower red blood cell production in diseases of excessive red cell production, e.g., PV.
Our Pipeline
We are building an innovative pipeline of product candidates that aim to modify fundamental biological pathways associated with the formation and function of red blood cells. We have obtained exclusive, worldwide licenses for the development and commercialization of bitopertin, DISC-0974, and DISC-0998, and exclusive rights for DISC-3405 and related antibodies in all territories outside of Greater China and Southeast Asia.
The diagram below reflects the status of our clinical-stage product candidates, bitopertin, DISC-0974 and DISC-3405, and related clinical trials, and our preclinical product candidate, DISC-0998. The timelines shown reflect our current expectations and beliefs based on our internal plans and regulatory interactions to date.
We also plan to develop bitopertin, DISC-0974 and DISC-3405 for other indications. For example, we are exploring the potential of bitopertin as a treatment for Diamond-Blackfan Anemia, or DBA, and other porphyrias.
Our Strategy
Our mission is to significantly improve the lives of patients suffering from hematologic diseases by developing differentiated product candidates designed to target fundamental pathways associated with the formation and function of red blood cells. To achieve our mission, we are pursuing increasingly large market opportunities as we grow and scale by focusing on the following key elements of our strategy:
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Obtain regulatory approval and successfully commercialize bitopertin for the treatment of patients with EPP, a well-defined rare disease with high unmet need. Based on our analyses of medical claims data, there are approximately 14,000 diagnosed EPP patients in the United States, and while the incidence of XLP is unknown, it is often estimated at one-tenth the incidence of EPP. There are currently no other disease-modifying therapies available to treat EPs such as EPP except bone marrow transplantation, which is associated with high rates of morbidity and mortality. The only other class of approved therapies for patients with EP are melanocortin 1 receptor agonists, which are designed to promote melanin production, or tanning, and thereby increase patient tolerance to sunlight. Based on the clinical data generated by Roche in multiple clinical trials in other indications, the compelling preclinical data we have generated, and the results of our BEACON and AURORA Phase 2 clinical trials, we believe bitopertin has the potential to be a disease-modifying treatment for these patients. In the CRL issued by the FDA in February 2026 in response to our NDA for accelerated approval of bitopertin in EPP and XLP, the FDA indicated that results from our ongoing Phase 3 APOLLO clinical trial of bitopertin in EPP and XLP patients could serve as evidence to support a potential traditional approval. We plan to request a Type A meeting to review our approach with the FDA, and we expect to report topline data from APOLLO in the fourth quarter of 2026, following which we plan to submit a response to the CRL.
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Build a franchise in myeloproliferative neoplasms, or MPNs, with significant unmet need by advancing the development of DISC-0974 and DISC-3405 for the treatment of anemia of MF and PV, respectively. We are initially developing our lead hepcidin-suppressing program, DISC-0974, for the treatment of anemia associated with MF, a rare,
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chronic blood cancer that currently affects an estimated 25,000 patients in the United States. At diagnosis, approximately 87% of patients with MF have anemia, which progressively worsens over time and ultimately renders the majority of patients dependent on chronic red blood cell transfusions. DISC-0974 is currently being evaluated in RALLY-MF, an open-label Phase 2 clinical trial in patients with anemia of MF. We reported initial data from this trial in December 2025, with results demonstrating meaningful overall anemia responses across all patient subgroups, regardless of baseline transfusion status and independent of concomitant JAK inhibitor therapy use. DISC-0974 was also generally well-tolerated. Topline data from this trial is expected in the second half of 2026, which, if positive, is expected to support discussions with regulatory agencies on the potential regulatory path for DISC-0974 in anemia of MF. The second program in our iron homeostasis portfolio is DISC-3405, which is designed to induce hepcidin production and which we are initially developing for the treatment of PV. PV is a chronic and rare MPN characterized by the overproduction of red blood cells and increased red cell mass that affects approximately 150,000 patients in the United States. In clinical trials conducted by third parties, iron restriction through a hepcidin mechanism resulted in disease control in patients with PV, and in our Phase 1 clinical trial of DISC-3405 in healthy adult volunteers, results showed an acceptable tolerability profile and evidence of target engagement, including dose-related increases in serum hepcidin and corresponding reductions in serum iron across all dose levels. We are currently studying DISC-3405 in RESTORE-PV, an open-label Phase 2 clinical trial of DISC-3405 in patients with PV, from which we expect initial data in the second half of 2026 and topline data in 2027.
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Expand our existing portfolio into a broad range of new indications, including SCD and anemias of inflammation. Though we have yet to generate complete clinical data for each of our product candidates, we believe that all of our current product candidates could have pipeline-in-a-product potential, and for each product candidate, we plan to explore its potential across multiple hematologic diseases. With respect to DISC-3405, we initiated a Phase 1b, open-label clinical trial in patients with SCD in October 2025, with initial data expected in the second half of 2026, and plan to explore the role of therapeutic iron restriction in other indications. With respect to DISC-0974, we initiated a Phase 2 clinical trial in patients with IBD and anemia in the first quarter of 2026, and we are planning exploratory studies in additional patient populations with anemia of chronic disease.
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Continue to build our pipeline through internal research or business development. We plan to leverage our expertise in hematology to further grow our pipeline through both internal discovery and development of new therapeutic candidates and in-licensing of external assets. This approach includes developing both next-generation programs to support our existing heme biosynthesis and iron homeostasis portfolios as well as molecules that target other pathways associated with red blood cells that may be of strategic and biological interest. For example, we are developing DISC-0998, a preclinical monoclonal antibody, as a next generation product candidate against HJV, the same target as DISC-0974. We believe DISC-0998 has improved pharmacokinetic, or PK, and pharmacodynamic, or PD, properties that may benefit certain subsets of patients with anemia associated with inflammatory diseases.
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Opportunistically evaluate strategic collaborations to maximize the value of our product candidates and preclinical programs. We have obtained exclusive, worldwide licenses for the development and commercialization of bitopertin, DISC-0974, and DISC-0998, and exclusive rights for DISC-3405 and related antibodies in all territories outside of Greater China and Southeast Asia. As we advance the development of our product candidates and preclinical programs across multiple indications and continue to generate additional data, we intend to continuously evaluate our options for maximizing the value of our overall portfolio. For example, in certain geographies, we may opportunistically enter into strategic collaborations to accelerate the development and maximize the commercial potential of any or all of our product candidates or preclinical programs. For each product candidate, preclinical program, indication, and geographic region, our goal is to find the best path forward for the development of our product candidates and preclinical programs in order to treat patients in need of new therapies, while also maximizing value for our stockholders.
Our Corporate History and Team
We were founded in 2017 with the mission to design, develop, and commercialize medicines for patients with hematologic diseases. Since inception, we have focused on building our pipeline of product candidates through both internal drug discovery activities and external business development, conducting preclinical studies and clinical trials, preparing for the potential commercialization of bitopertin, if approved, and establishing and maintaining our intellectual property portfolio.
We have assembled a management team with extensive experience in successfully developing, manufacturing, and commercializing transformative therapies as well as in business development and alliance management. Collectively, our team led, or was involved in, the development, regulatory approval, and commercialization of therapies for hematologic diseases, such as Idhifa, Reblozyl, Pyrukynd, Adynovate, Tibsovo, Casgevy, and Roxadustat, as well as numerous late-stage clinical and approved therapies for other therapeutic areas. Our team has significant previous experience at leading biotechnology and pharmaceutical companies, including Acceleron Pharma, Inc., Agios Pharmaceuticals, Inc., Albireo Pharma, Inc., Bristol-Myers Squibb Company, CRISPR Therapeutics AG, FibroGen, Inc., Genzyme Corporation, Johnson & Johnson, Merck & Co., Inc., Pfizer Inc., Replimune Group Inc., Takeda Pharmaceutical Co., Vertex Pharmaceuticals Incorporated, and The Medicines Company. Our management team’s wide-ranging
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expertise in rare diseases, hematology, medicinal chemistry, protein biochemistry, and clinical development provide a singular vision for building a company focused on fundamental mechanisms to develop treatments for patients with hematologic diseases.
Our Heme Biosynthesis Modulation Portfolio
Our first therapeutic approach is focused on the treatment of diseases caused by defects in heme biosynthesis, a multistep enzymatic process that is critical for the formation of new red blood cells. Heme is an essential part of red blood cells, and when complexed into the hemoglobin protein, it performs the vital function of transporting oxygen throughout the body. However, genetic or acquired defects in the enzymes that mediate heme biosynthesis, as well as deficiencies in the incorporation of heme into hemoglobin, can result in the accumulation of toxic metabolites, leading to a range of hematologic diseases.
Heme Biosynthesis: Fundamental to Erythropoiesis
Erythropoiesis is the biological process by which precursor cells in the bone marrow mature to become red blood cells. The primary function of red blood cells is to transport oxygen throughout the body. Hemoglobin, an iron-containing protein found in all red blood cells, is responsible for binding to oxygen in the lungs, transporting it throughout the body and releasing it in peripheral tissues. The key oxygen binding function of hemoglobin is mediated by its heme component, a molecular complex comprising a porphyrin molecule and iron. Because red blood cells consist largely of heme-containing hemoglobin, newly forming red blood cells must synthesize tremendous amounts of heme. Heme biosynthesis is a complex process that begins with the amino acid glycine and requires multiple subsequent enzymatic reactions, as shown in the figure below. Heme is a highly reactive and potentially toxic complex, as are many of the porphyrin molecules that are generated as metabolic intermediates during heme biosynthesis. As a result, heme biosynthesis is tightly regulated to avoid a build-up of free heme or porphyrins. As new red blood cells are forming in the bone marrow, the heme biosynthesis pathway is tightly coordinated with the expression of the protein subunits of hemoglobin, the globins, and the uptake of iron. The vast majority of newly synthesized heme is incorporated into hemoglobin and does not accumulate in free form to toxic levels. Moreover, the entire process of erythropoiesis is regulated by the availability of heme. As a result, agents that affect heme biosynthesis have broad potential to treat diseases of the heme and hemoglobin biosynthesis pathways and other hematologic diseases resulting from dysregulated erythropoiesis.
Overview of the Heme Biosynthesis Process - Eight Enzymatic Steps from Glycine to Heme
Heme Biosynthesis as a Therapeutic Target for Diseases
In many hematologic diseases, there is abnormal proliferation and differentiation of the progenitor cells that develop into red blood cells. An alteration in any aspect of red blood cell maturation can result in the build-up of metabolic intermediates from heme and hemoglobin biosynthesis, and these intermediates can cause a variety of disease states. Defects of the heme biosynthesis enzymes in the erythroid lineage can cause the build-up of metabolic intermediates called porphyrins and lead to a set of diseases referred to as EPs. In EPs, porphyrins accumulate to inappropriately high levels and cause damage, particularly in the skin, gallbladder, and liver. Similarly, defects in globin biosynthesis, often caused by mutations in the ribosomes that are necessary for mediating globin biosynthesis, result in the build-up of heme that is not complexed with globin. This free heme can damage newly forming red blood cells, leading to forms of anemia observed in DBA and in certain types of myelodysplastic syndromes, or MDS. In diseases characterized by defects in the genes coding for the globins, such as sickle cell disease and beta thalassemia, the reduction of heme biosynthesis has the potential to reduce the production of pathologically altered globins that aggregate or polymerize, causing oxidative damage and hemolysis. In people without globin abnormalities, excessive production of red blood cells with normal hemoglobin can cause PV, in which the higher hematocrit can lead to thrombotic disease, including stroke. Restricting heme formation has the potential to ameliorate symptoms in certain patients with these hemoglobinopathies and disorders of red blood cell excess. Therefore, we believe that inhibitors of heme biosynthesis have the potential to treat a wide range of hematologic diseases by restricting the production of damaging metabolites, including porphyrins, heme and globins.
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Erythropoietic Porphyrias
EPs are a family of rare, debilitating, and potentially life-threatening diseases caused by mutations that affect the heme biosynthesis pathway. These mutations result in the toxic accumulation of metabolic intermediates in the blood called porphyrins, which can absorb light through the skin and mediate the generation of toxic reactive oxygen species that cause damage to the skin and other tissues. Consequently, when patients with porphyria are exposed to sunlight, they experience excruciating pain, blistering, and edema in the skin. This severe phototoxicity often results in a lifelong aversion to and fear of light, which has a negative impact on patients and their families, particularly for young children. These effects include impaired psychosocial development and conditions, such as anxiety, depression, and social isolation that may require significant adjustments to career and other life choices. EPs comprise three subtypes that are each linked to a specific mutation or deficiency in one of the enzymes in the heme biosynthesis pathway: (1) EPP, which is linked to the ferrochelatase, or FECH, enzyme; (2) XLP, which is linked to the delta-aminolevulinic acid synthase-2, or ALAS2, enzyme; and (3) congenital erythropoietic porphyria, or CEP, which is linked to the uroporphyrinogen III cosynthase, or UROS, enzyme. As shown below, mutations in the FECH and ALAS2 enzymes lead to a pathological accumulation of PPIX, and as a result, patients with EPP or XLP typically have high levels of PPIX.
Genetic and Biochemical Basis for EPP and XLP: FECH and ALAS2 Mutations Increase PPIX Levels
EPP is a rare, inherited metabolic disease characterized by a deficiency of the FECH enzyme. FECH is responsible for the last step in heme biosynthesis and catalyzes the insertion of iron into PPIX to create the final heme moiety. In patients with EPP who have abnormally low levels of FECH, excessive amounts of PPIX accumulate in the bone marrow, blood plasma, and red blood cells. This accumulation of PPIX, which becomes highly reactive and toxic when exposed to light, causes the hallmark EPP symptom of photosensitivity, or skin hypersensitivity to sunlight and some types of artificial light, such as fluorescent lights. After exposure to light, the patient’s skin may initially become itchy and red, and then affected individuals often experience a severe burning sensation that may persist for days. PPIX also accumulates in the gallbladder and liver and causes complications in these organs for some patients. An estimated 25% of patients may develop gallstones that require surgical removal. Many patients live with subclinical liver damage, which progresses to overt liver failure and requires liver transplant in approximately 2% to 5% of patients. The onset of symptoms affecting the skin usually occurs in early childhood; however, in some cases, onset may not occur until adolescence or adulthood. EPP has been reported worldwide, with prevalence between 1 in 75,000 to 1 in 200,000, but a recent genetic study suggests that the genetic prevalence may be higher at approximately 1 in 17,000. Recent analyses we completed of medical claims data using the ICD-10 code for EPP suggests there are approximately 14,000 diagnosed patients in the U.S.
XLP is a genetically distinct inherited metabolic disease with a clinical presentation that is similar to EPP. The causative mutation in XLP occurs in the ALAS2 gene, which codes for the first enzyme in the heme biosynthesis pathway that is found on the X chromosome and inherited with an X-linked pattern. The mutation causes increased ALAS2 function, which results in pathologic accumulation of PPIX. XLP affects both males and females, but males usually develop a severe form of the disease. Females with an ALAS2 mutation may also develop the disease, but severity can range from being asymptomatic to a severe form. Similar to EPP, the major symptom of this disease is skin hypersensitivity to sunlight and some types of artificial light. The exact incidence or prevalence of XLP is unknown, but it is often estimated at one-tenth the incidence of EPP. EPP and XLP, when combined, are the third most common porphyria.
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CEP, also known as Günther Disease, is the rarest and most severe form of the EPs and results from the deficient function in UROS, the fourth enzyme in the heme biosynthesis pathway. In CEP, the impaired function of this enzyme leads to the accumulation of excessive amounts of certain porphyrins, particularly in the bone marrow, plasma, red blood cells, urine, teeth, and bones. Similar to EPP and XLP, the major symptom of this disease is skin hypersensitivity to sunlight and some types of artificial light. However, in patients with CEP, the photoactivated porphyrins in the skin cause more profound blistering and scarring. Additionally, the accumulation of porphyrins in the bone impairs bone metabolism and can cause bone loss and deformities. CEP is extremely rare and there have been about 220 affected individuals reported to date.
Current Treatment Options for Erythropoietic Porphyrias
There are currently no disease-modifying therapies available to treat EPs other than bone marrow transplantation, which is associated with high rates of morbidity and mortality. Lifestyle alterations to avoid light exposure are the primary approach to managing phototoxicity in EP patients. Sunscreens, tinted windows, and protective clothing are also commonly used in addition to behavioral modifications. The only class of approved therapies for patients with EP are melanocortin 1 receptor agonists, which are designed to promote melanin production, or tanning, and thereby increase patient tolerance to sunlight. Afamelanotide, an a-melanocyte-stimulating hormone analog delivered by a surgically-administered subcutaneous implant, was approved by the FDA in 2019 for the treatment of adults with EPP. Afamelanotide provides reduction in photosensitivity, but is not designed to reduce PPIX production and is associated with side effects, such as nausea, hyperpigmentation and a darkening of or increase in melanocytic nevi. In a pivotal trial, afamelanotide increased the median number of pain free hours in daytime (10am to 6pm) over 180 days from 40.5 hours in a placebo group to 64.1 hours in the treatment group. Another melanocortin 1 receptor agonist, dersimelagon, which is orally administered, recently completed a Phase 3 clinical trial run by a third party. Overall, there remains a significant unmet need despite the use of melanocortin 1 receptor agonists, as they provide incomplete resolution of photosensitivity and more importantly, are not designed to reduce the production of protoporphyrins or address hepatobiliary complications, such as gallstones and progressive liver disease.
Patients with EP who have progressive liver damage are managed through periodic monitoring, and in cases of liver failure, transplantation is required. While bone marrow transplantation has been used to cure EPs, it is associated with high rates of morbidity and mortality. Therefore, this procedure is usually considered only for younger patients after a liver transplant, for older patients with recurrent disease affecting the liver allograft, or for patients with progressive liver disease.
Relationship Between PPIX Levels and EPP/XLP Symptoms
EPP and XLP are diseases marked by severe photosensitivity and damage to the hepatobiliary system caused by the accumulation of PPIX. PPIX has been well-characterized to absorb light and induce inflammation and tissue damage, manifesting clinically as painful phototoxic reactions. Lower levels of PPIX are associated with lower disease severity. Epidemiologic data correlate increasing PPIX concentrations with decreased light tolerance, and interventions that reduce PPIX in patients correlate directly with increased light tolerance. Lower PPIX levels (by roughly 30-50%) increased light tolerance in patients. 25% of patients with lower PPIX levels experienced symptoms versus 75-100% of patients with medium to high PPIX levels under controlled light exposure. During pregnancy, women with EPP experience temporary disease remissions that increase sunlight tolerance and coincide with a reduction in PPIX levels. For example, in a study conducted by a third-party, pregnant women were observed to have a median reduction of 53% in PPIX levels during pregnancy, resulting in a significant reduction in their EPP symptoms. Disease symptoms return after delivery when PPIX levels revert to pre-pregnancy levels, leading to the hypothesis that the fetus may utilize plasma PPIX as a substrate for its own escalating heme biosynthesis requirements, thus reducing PPIX levels in the mother’s bloodstream. In a third-party study of extracorporeal photoinactivation, a process that reduces circulating PPIX levels, symptoms were markedly improved after reduction in blood PPIX concentrations. In this study, blood was removed from the body and illuminated with controlled wavelength light to inactivate PPIX, and the blood in which the PPIX was inactivated was re-infused. This procedure resulted in PPIX reductions of approximately 30% and light tolerance was temporarily increased 14-fold, a level of improvement that is expected to permit near-normal patient lifestyle. However, given the technical complexities associated with this procedure, it has not been widely adopted as a therapeutic option in patients.
Our Solution: Bitopertin, an Oral, Selective GlyT1 Inhibitor
Bitopertin is designed to be an oral, selective inhibitor of GlyT1, a key membrane transporter required to supply developing red blood cells with sufficient glycine to support erythropoiesis. By limiting glycine uptake at the first step in heme biosynthesis in newly forming red blood cells, bitopertin is designed to reduce the activity of this pathway and therefore has the potential to treat a range of hematologic disorders associated with the biosynthesis of heme and hemoglobin that are characterized by porphyrin toxicity or heme toxicity.
We are initially focused on the ability of bitopertin to suppress the accumulation of PPIX. Based on its mechanism of action, we believe bitopertin has the potential to be a disease-modifying treatment for EPP and XLP.
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We believe that the findings from our preclinical studies, our clinical trials, and the clinical trials conducted by Roche demonstrate that bitopertin has the potential to act as a durable, and well-tolerated inhibitor of heme biosynthesis in humans. Importantly, we believe these studies support the potential for bitopertin to reduce PPIX to a degree that has, in third-party studies, been associated with marked symptom improvement in patients with EPP and XLP.
Roche Clinical Data
In May 2021, we licensed exclusive worldwide rights to develop and commercialize bitopertin from Roche. Roche had previously developed bitopertin as a potential therapy for certain symptoms of schizophrenia and obsessive-compulsive disorder, but chose to discontinue the program due to failure to meet primary endpoints in Phase 3 trials for the lead indication after completing over 30 clinical trials in more than 4,000 individuals. Roche conducted a pilot study for the treatment of anemia in 12 patients with beta-thalassemia, a population with a normal heme biosynthesis pathway; this trial did not show consistent increases in hemoglobin at the doses tested. Despite the observed lack of efficacy, the clinical program established a well-defined and generally well-tolerated profile for bitopertin. Importantly, these trials confirmed that bitopertin inhibits glycine uptake in red blood cells and demonstrated the role of GlyT1 inhibition in heme biosynthesis during red blood cell production. A mild, dose-dependent decrease in heme biosynthesis was observed in multiple clinical trials, which manifested as a decrease in hemoglobin of approximately 0.5 to 2 g/dL that stabilized after approximately 16 weeks, the approximate lifespan of a red blood cell.
For example, a single dose clinical trial in healthy volunteers evaluating bitopertin at doses ranging from 3 mg to 80 mg administered once-daily in 24 individuals demonstrated dose-dependent inhibition of erythrocyte glycine uptake levels, as shown below.
Bitopertin Inhibited Erythrocyte Glycine Uptake in Humans in a Dose-Dependent Manner
In multiple Phase 3 clinical trials, Roche demonstrated that in patients with schizophrenia who are otherwise hematologically normal, inhibition of glycine uptake resulted in a reduction in hemoglobin production. Patients were administered placebo or bitopertin at 10 mg/day or 20 mg/day dose levels. The effect on hemoglobin was dose-dependent, with patients receiving 10 mg/day and 20 mg/day of bitopertin experiencing a mean decrease in hemoglobin at 52 weeks of approximately 0.5 g/dL and approximately 1.0 g/dL, respectively. The effect of bitopertin on hemoglobin reached a plateau at approximately week 26 and effects were generally stable for the remainder of the 52-week trial.
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The comprehensive data package from Roche’s healthy volunteer trials provides further support for bitopertin's tolerability profile. The identified risks established by Roche across the development program are (percentage bitopertin treated vs. percentage placebo treated): headache (9.8% vs. 6.7%), somnolence (5.2% vs. 3.7%), and dizziness (4.2% vs. 3.6%). The results of single dose bitopertin clinical trials in healthy volunteers at doses ranging from 3 mg to 240 mg (n=290) and multiple dose trials at doses ranging from 10 mg to 180 mg daily for 10 to 120 days (n> 360) did not demonstrate any significant tolerability issues. In one multiple ascending dose trial, reversible blurred vision was observed in 5 subjects (20%) at or above the 80 mg/day dose level. In a four-month pharmacodynamics study, 11.8% of subjects receiving an active dose noted dysphoria/low mood (mostly at 30 mg/day), as compared to 6.3% of placebo, and dermatological adverse events on hands and feet were observed in 15.7% of subjects (mostly at 60 mg/day). In Phase 3 studies, no association with bitopertin was found for dermatological adverse events or adverse events of blurred vision or low mood. The amount of hemoglobin per red blood cell or per reticulocyte decreased in a dose-dependent manner. No hematologic parameter reached a level at which we would expect clinical signs or symptoms. Roche’s Phase 3 program in schizophrenia consisted of six Phase 3 clinical trials (n=2,438) of 5 mg, 10 mg, and 20 mg doses of bitopertin for up to 52 weeks, followed by extension phases. In these trials, bitopertin treatment was not associated with any significant tolerability issues. Most of the adverse events were considered mild or moderate in severity in these trials.
BEACON: Completed Phase 2 Clinical Trial in Patients with EPP and XLP
In July 2022, we initiated BEACON, a Phase 2 clinical trial of bitopertin in EPP and XLP patients conducted at sites in Australia. The study was a randomized, open-label, parallel-dose clinical trial designed to evaluate the safety, tolerability, and efficacy of bitopertin. It enrolled 22 adult patients and four adolescent patients with EPP or XLP. The study primarily assessed changes in levels of PPIX as well as the PK profile, safety and tolerability of bitopertin in EPP or XLP patients. It also included measures of photosensitivity, daylight tolerance, pain and exploratory biomarkers of hepatobiliary disease. Patients received orally-administered bitopertin for 24 weeks at doses of either 20 mg once-daily or 60 mg once-daily. These dose levels have a well-understood profile and similar dosage strengths have been shown to provide substantial inhibition of erythroid glycine uptake in the clinical trials conducted by Roche. The trial design is summarized in the figure below. Participants in the BEACON trial were eligible to participate in HELIOS, an ongoing open-label, long-term extension study of bitopertin in EPP and XLP.
BEACON Trial Design: Open-Label, Phase 2 Clinical Trial of Bitopertin in Patients with EPP
or XLP (N = 22 adults, N = 4 adolescents)
Interim data from BEACON were presented at the European Hematology Association, or EHA, annual meeting in June 2023 and at the American Society of Hematology, or ASH, annual meeting in December 2023. Additional analyses were presented at the EHA annual meeting in June 2024 and at the ASH annual meeting in December 2024. Twenty-one of the 22 enrolled adults and three of the four enrolled adolescents completed the study. The average age of the adult participants was 44 years, with 64% being female. Bitopertin significantly reduced PPIX in both the adult and adolescent populations, with reductions of whole blood metal-free PPIX of >40% compared to baseline in the overall adult study population, and with greater reductions in the 60 mg group than the 20 mg group. Most of the PPIX reduction occurred in the first 6 weeks of treatment. Overall, there was a 92% reduction in the incidence of patient-reported full phototoxic reactions compared to baseline. The proportion of symptom-free days improved from 33% at baseline to 79% while taking bitopertin. Sunlight tolerance improved in a series of sunlight challenges that participants self-administered weekly, according to the protocol. People with EPP experience prodromes, or early warning symptoms, of an impending full phototoxic reaction. These prodromes are reversible when sunlight exposure is discontinued, and the time until a prodrome starts is an indicator of light tolerance. Combining data from all adult participants showed a >3-fold improvement in average time to prodrome, as compared to baseline (p<0.01). The proportion of adult participants who conducted a sunlight challenge that did not elicit a prodrome increased from 7% at baseline to 55% while taking bitopertin. Of the adult participants that completed at least 4 months of treatment (n=21), nearly all reported improvements in quality of life measures, with 20 of 21 reporting that their EPP was “much better” or “a little better”, 19 of 21 reporting that their EPP was “not at all” or “mild” in severity, and 18 of 21 reporting that EPP impacted their quality of life in the last 7 days “not at all” or “a little bit”.
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BEACON: Primary Endpoint – Percent Change in Whole Blood PPIX
BEACON: Associations between PPIX Reductions and Light Tolerance
Safety analyses showed no serious adverse events, stable hemoglobin levels, and no anemia adverse events reported. There was one discontinuation due to an adverse event that was assessed as probably related to bitopertin treatment: a Grade 3 headache in an adult participant. Overall, 65% of participants reported dizziness, 15% of participants reported headache, and 12% of participants reported nausea.
AURORA: Completed Phase 2 Clinical Trial in Patients with EPP
Separately, in October 2022 we initiated AURORA, a Phase 2, randomized, double-blind, placebo-controlled, parallel dosing trial in 75 adult patients with EPP conducted at sites in the United States. We enrolled patients into a placebo group (n=24), a 20 mg/day dose group (n=26) and a 60 mg/day dose group (n=25), with bitopertin delivered as tablets taken orally once per day for a period of 17 weeks. These dose levels have a well-understood profile and similar dosage strengths have been shown to provide substantial inhibition of erythroid glycine uptake based on the clinical trials conducted by Roche. This trial included assessments of blood PPIX levels, with a primary endpoint of percent change in whole blood metal-free PPIX, and patient photosensitivity, including a secondary endpoint of cumulative total time in sunlight between 10:00 a.m. and 6:00 p.m. on days without pain observed over the four-month treatment period. The FDA has previously approved afamelanotide for the treatment of photosensitivity in adult EPP patients on the basis of a clinical endpoint measuring a change in pain-free time spent in sunlight in treated patients, relative to patients treated with placebo. Additional study measures included time to prodrome, hepatobiliary markers, quality of life, safety and tolerability, among others. The trial design is summarized in the figure below. Participants in the AURORA trial were eligible to participate in HELIOS, an ongoing open-label, long-term extension study of bitopertin in EPP and XLP.
AURORA Trial Design: Randomized, Double-Blind, Placebo-Controlled Phase 2 Clinical Trial of Bitopertin in Patients with EPP (N = 75)
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We presented topline data from AURORA in April 2024. Additional analyses were presented at the EHA annual meeting in June 2024 and at the ASH annual meeting in December 2024. Seventy-two of the 75 participants completed the study. With respect to the primary endpoint, bitopertin resulted in significant, dose-dependent, and sustained reductions in whole blood PPIX levels compared to baseline (-21.5% for 20 mg (p=0.004 vs placebo) and -41.7% for 60 mg (p<0.001 vs placebo); the placebo group had mean increases of +8.1%). As in BEACON, most of the PPIX reduction occurred in the first 6 weeks of treatment. With respect to clinical efficacy endpoints, there were substantial and dose-dependent reductions in phototoxic reactions with pain during the four-month study period, consisting of a 75% reduction in the incidence rate of new phototoxic reactions with pain at the 60 mg dose group compared to placebo (p=0.011), and a 60% reduction in the 20 mg dose group compared to placebo (p=0.109). Fewer bitopertin-treated patients reported a phototoxic event compared to placebo (19% for 20 mg and 12% for 60 mg compared to 46% for placebo). There were also dose-dependent improvements in quality-of-life scores as measured by the Patient Global Impression of Change, or PGIC, scale, which were statistically significant for the 60 mg dose: 77% of completers at 20 mg and 86% at 60 mg (p=0.022 vs placebo) reported that their EPP was “much better” compared with 50% for placebo. With respect to cumulative total time in sunlight on days without pain, bitopertin-treated patients recorded a mean of 175.1 hours at 20 mg and 153.1 hours at 60 mg, compared with 133.9 hours for placebo. While the magnitude of the improvement in the bitopertin-treated patients from baseline was comparable to that observed in the BEACON study, the benefit in the placebo arm in the AURORA trial was greater than expected and the results were not statistically significant compared to placebo. In addition, there were large improvements in light tolerance from baseline in 20 mg and 60 mg bitopertin treatment groups as measured by time to prodrome, but the results were not statistically significant relative to placebo. However, a post-hoc longitudinal analysis showed time-dependent improvement in light tolerance that was nominally significant compared to placebo in both the 20 mg (p=0.026) and 60 mg (p=0.013) dose groups, and a two-fold improvement in light tolerance relative to baseline in both 20 mg and 60 mg dose groups. Greater PPIX reductions were associated with improvements in multiple light tolerance measures, including cumulative total time in light, average time in sunlight without pain, change from baseline in time to prodrome, as well as PGIC, and evaluation of the time course of phototoxic reactions and sunlight exposure showed greater treatment effect in the time period after the PPIX nadir was reached, including elimination of observed phototoxic reactions in the 60 mg dose group.
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AURORA: Primary Endpoint – Percent Change in Whole Blood PPIX
AURORA: Association between PPIX Change and Clinical Measures with Bitopertin
Bitopertin was generally well tolerated in both dose groups with no serious adverse events and stable hemoglobin levels. Two patients discontinued treatment due to treatment-emergent adverse events, both in the 60 mg dose group and both of which were assessed as possibly related to bitopertin: one due to dizziness and one due to a skin rash. The most common adverse event reported with bitopertin treatment was dizziness: n=4 in the 20 mg dose group and n=11 in the 60 mg dose group, compared with n=3 in the placebo group (median durations of 8.5, 5.0, and 1.0 days, for the 20 mg, 60 mg, and placebo groups, respectively).
HELIOS: Ongoing Phase 2 Open-Label, Long-Term Extension Study of Bitopertin in Patients with EPP and XLP
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HELIOS is an ongoing Phase 2, open-label, long-term extension trial of bitopertin in patients with EPP and XLP that enrolled 86 adult and adolescent patients with EPP from the BEACON and AURORA trials. Patients were randomized to receive 20 mg or 60 mg bitopertin in BEACON and 20 mg or 60 mg bitopertin or placebo in AURORA, with all patients transitioning to a 60 mg daily dose of bitopertin in HELIOS. The primary and secondary endpoints of this trial are safety and tolerability and percent change in whole blood metal-free PPIX, respectively. Additional study assessments include a daily sun exposure diary, patient-reported quality of life and liver fibrosis measurements.
Interim data from this trial was first presented at the EHA annual meeting in June 2025. Of the 86 enrolled patients, data were presented from the 67 participants who had completed a 24-week treatment period as of a February 4, 2025 data cutoff date. Two participants withdrew early from the trial due to an adverse event. Results demonstrated that longer term treatment with bitopertin was associated with sustained reductions in PPIX, with additional benefit for patients receiving the 60 mg dose continuously. In addition, continuous treatment with 60 mg of bitopertin was associated with reduction of alanine aminotransferase, or ALT, and other exploratory hepatobiliary biomarkers, and nearly all participants reported substantial improvements in quality of life measures. In this interim dataset, bitopertin exhibited a favorable longer-term safety profile with up to 2+ years of exposure and similar safety results across adults and adolescents with EPP and XLP.
APOLLO: Ongoing Phase 3 Randomized, Double-Blind, Placebo-Controlled, Clinical Trial of Bitopertin in Patients with EPP and XLP
In December 2024, we aligned with the FDA on the design of APOLLO, a Phase 3, randomized, double-blind, placebo-controlled, clinical trial of bitopertin in EPP and XLP patients. Key features of the trial include:
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Co-primary endpoints of average monthly total time in sunlight without pain between 10:00 a.m. and 6:00 p.m. during the last month of the six-month treatment period and percent change from baseline in whole blood metal-free PPIX after six months of treatment;
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Other measures of efficacy such as occurrence of phototoxic reactions, cumulative total pain-free time in sunlight, PGIC, and time to prodrome;
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Selection of 60 mg dose of bitopertin and six-month treatment duration;
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Inclusion of patients aged 12+ with EPP, including XLP; and
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Double-blind, placebo-controlled study with at least 150 patients randomized 1:1 across sites in the United States, Canada, Europe and Australia.
We initiated the APOLLO trial in May 2025 and anticipate topline data in the fourth quarter of 2026.
NDA for Bitopertin in EPP and XLP
In our end-of-Phase 2 meeting in September 2024, the FDA agreed with the potential for reduction of PPIX to serve as a surrogate endpoint to support a potential accelerated approval of bitopertin in EPP and XLP. In our Type C meeting in December 2024, we aligned with the FDA on the design of our APOLLO clinical trial, that in the setting of an accelerated approval would serve as a post-marketing confirmatory trial. In September 2025 we submitted an NDA for accelerated approval of bitopertin in EPP and XLP in the United States based on our existing data. In October 2025, we were awarded a CNPV from the FDA for bitopertin in EPP and XLP. The CNPV program, announced in June 2025, is designed to accelerate the development and review of certain drugs aligned with US national health priorities. The FDA accepted our NDA for review in November 2025 and in February 2026 issued a CRL. Although the FDA agreed that clinical data from AURORA and BEACON provided sufficient evidence that bitopertin significantly lowers whole blood metal-free PPIX, the FDA concluded that the trials did not show evidence of association between percent change in PPIX and sunlight exposure-based endpoints as measured in the trials. As such, the FDA determined that there is uncertainty regarding whether bitopertin’s effect in PPIX is reasonably likely to predict clinical benefit, despite the strong mechanistic and biological plausibility supporting the use of the PPIX biomarker in protoporphyria. The FDA indicated that results of the ongoing APOLLO trial could serve as evidence to support a potential traditional approval, and we plan to request a Type A meeting to review our approach with the FDA. We plan to submit a response to the CRL following receipt of topline data from the APOLLO clinical trial, which we expect to report in the fourth quarter of 2026. The APOLLO trial is also intended to serve as a registrational trial with respect to any potential future marketing applications for bitopertin in EPP and XLP outside the United States.
Bitopertin in Additional Indications: Diamond-Blackfan Anemia
We believe that bitopertin may be therapeutically beneficial for the treatment of DBA. DBA is a genetic condition marked by defective erythropoiesis that is usually caused by genetic mutations in genes coding for ribosomal proteins. Clinically, DBA is a lifelong anemia that presents in infancy and has a 25% mortality rate by age 50. Standard therapy includes chronic steroid treatment and/or regular blood transfusions, and hematopoietic stem cell transplantation is the only known cure for DBA. The ribosomal defects in patients with DBA are thought to cause a build-up of free heme in newly forming red blood cells, and this free heme
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exerts a toxic effect, resulting in poor red blood cell formation and anemia. Inhibitors of heme biosynthesis have shown marked effects in improving red blood cell production in third-party cellular and animal models of DBA. Accordingly, we anticipate that bitopertin may be able to provide relief from anemia and transfusion in patients with DBA by restricting the accumulation of toxic, free heme. We have entered into a collaborative research and development agreement with the NIH to conduct an NIH-sponsored clinical trial of bitopertin in DBA, which trial began in July 2023 and results were reported in December 2025. In this trial, bitopertin was generally well-tolerated, and bioavailability, pharmacokinetics and effects upon hemoglobin were consistent with the Roche clinical data set. Although bitopertin did not yield transfusion-independence in these patients, the baseline iron overload, marrow hypocellularity and prior failure of steroids reflected a cohort with long-standing disease and minimal erythropoietic marrow reserve.
Our Iron Homeostasis Portfolio
In addition to our heme biosynthesis therapeutic approach, we are developing a portfolio of product candidates focused on the modulation of the hepcidin pathway to normalize iron homeostasis. Iron is an essential element that is required for erythropoiesis as well as other important biological functions. Nearly 70% of iron in the human body resides in red blood cells, where it is a fundamental component of hemoglobin, the protein that enables red blood cells to carry and transport oxygen. Although iron is critical to an array of biological functions, excessive levels can be toxic. Consequently, the management of iron levels in the body is a critical and carefully controlled process. Hepcidin is a potent hormone produced in the liver that serves as the primary regulator of iron homeostasis and plays a central role in controlling how iron is absorbed, utilized, stored, and recycled systemically. If this process becomes dysregulated, a wide range of serious, debilitating, and potentially fatal conditions can arise.
Hepcidin: The Master Regulator of Iron Homeostasis
Iron typically enters the body when it is absorbed in the intestine from dietary intake. As it enters circulation, iron is bound to carrier proteins. Iron is a highly reactive metal that can cause oxidative stress and tissue damage in an unbound state. Iron is utilized in target tissues, such as the bone marrow, to support erythropoiesis, and the remaining surplus is directed to specific storage tissues, such as the spleen, where it can be sequestered in specialized macrophages and redeployed when needed. This process is governed by hepcidin, which serves as a gatekeeper in tissues that are a source of iron, both blocking absorption of dietary iron from the intestine and preventing the release of stored iron from the spleen, as shown in the figure below. The body exerts control and responds to demands for iron by increasing or reducing the production of hepcidin, which leads to a reduction or increase in iron availability, respectively.
Hepcidin Plays a Central Role in Iron Metabolism and Homeostasis
Hepcidin is a Therapeutic Target for Diseases of Iron Metabolism
Because iron is critical to so many biological functions, particularly in red blood cells, disruptions in its homeostasis, often due to the dysregulated production of hepcidin, can result in a wide range of hematologic diseases, as shown in the figure below. These include diseases that can cause abnormally high production of hepcidin, which deprives developing red blood cells of iron and causes anemia, a frequent complication of cancer, autoimmune conditions, and other inflammatory diseases. Conversely, in certain diseases with abnormally low production of hepcidin, increasing hepcidin and restricting iron availability are expected to provide a therapeutic benefit. For example, in PV, iron restriction through a hepcidin mechanism has been demonstrated to control pathologic production of red blood cells. In other diseases, such as SCD, iron restriction and agents that increase hepcidin could be beneficial by lowering the concentration of sickle hemoglobin inside red blood cells and reducing the tendency of red blood cells to sickle and hemolyze, the red blood cell processes which can lead to the clinical sequelae in SCD.
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Dysregulated Hepcidin Drives a Wide Range of Hematologic Diseases
We believe that modulating the production of hepcidin to correct pathologic alterations in iron metabolism has the potential to be a powerful therapeutic strategy to address a wide range of diseases. We are leveraging two approaches that are designed to suppress or induce hepcidin production in order to increase or decrease serum iron levels, respectively. Our product candidates target novel pathways whose biological functions have been validated by human genetics and are specific to iron modulation.
Hepcidin Suppression
We are developing a portfolio of product candidates designed to lower hepcidin and restore serum iron levels to address anemia of inflammatory diseases. Our lead product candidate, DISC-0974, is a monoclonal antibody, which we in-licensed from AbbVie, that is designed to inhibit HJV, a critical target for hepcidin production. We selected this target because the effects of inhibiting HJV, namely decreased hepcidin and increased iron availability, have been genetically demonstrated in both animal knockout studies and in patients with juvenile hemochromatosis who lack fully functional genes encoding HJV.
Hepcidin Induction
We are also developing a portfolio of product candidates designed to increase hepcidin and decrease serum iron levels, an approach that has the potential to address a range of diseases where restricting iron would be beneficial, such as excessive red blood cell production in PV and diseases of iron overload. Our lead program, DISC-3405, which we licensed from Mabwell, is a monoclonal antibody designed to inhibit TMPRSS6, a serine protease that normally serves to limit hepcidin production. By inhibiting TMPRSS6, our compounds have the potential to increase production of hepcidin and, in turn, restrict iron availability. We selected this target based on the genetic confirmation of the effects of inhibiting TMPRSS6 in both animal knockout studies and in patients with iron-refractory iron deficiency anemia who lack fully functional genes encoding TMPRSS6.
Our Lead Hepcidin Suppression Program: DISC-0974 For the Treatment of Anemia of Inflammatory Diseases
We are developing DISC-0974, our lead antibody product candidate targeting hepcidin suppression, for the treatment of anemia resulting from iron restriction that typically occurs in the setting of inflammatory diseases. DISC-0974 is designed to be a selective inhibitor of HJV, a bone morphogenetic protein, or BMP, co-receptor. Inflammatory signals, potentiated by BMP signaling, are an underlying cause of elevated levels of hepcidin, leading to low iron bioavailability and subsequent anemia in a broad range of diseases. We believe that abnormally high levels of hepcidin are an important driver of anemia associated with inflammatory diseases and that suppression of hepcidin with DISC-0974 has the potential to provide meaningful benefit in these patients.
Overview of Anemia Associated with Inflammatory Diseases
Anemia of inflammation is a hallmark of a wide range of autoimmune and chronic diseases, including MF, IBD, CKD, rheumatoid arthritis, cancer, obesity, chronic obstructive pulmonary disease, and cardiovascular disease. Anemia occurs frequently in these diseases and for example, affects approximately 87% of MF, 25-35% of IBD, 17-50% of CKD, 35-80% of cancer, and 50% of lupus patients. It is a common cause of chronic anemia and has been estimated to affect over one billion individuals worldwide. This type of anemia is caused by the sustained inflammation associated with these diseases, which produces a host of pro-inflammatory cytokines that impair erythropoiesis. Importantly, these cytokines have an impact on iron homeostasis by inducing the production of hepcidin, which in turn deprives developing erythrocytes of iron. There are currently no approved therapies designed to primarily lower hepcidin, and most patients remain anemic or untreated.
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Anemia of Myelofibrosis
MF is a rare, chronic blood cancer that currently affects an estimated 25,000 patients in the United States. It is characterized by progressive fibrosis of the bone marrow brought on by the proliferation of cytokine-producing myeloid cells, which creates a state of chronic inflammation. Severe, progressive, and treatment- resistant anemia is the primary clinical manifestation of MF, and a study in over 200 patients at the Mayo Clinic showed that hepcidin is elevated by approximately 12-fold in these patients, as shown below. Elevated hepcidin levels are correlated with disease severity, anemia, and the need for red blood cell transfusions.
At diagnosis, approximately 87% of patients with MF have anemia, which progressively worsens over time and ultimately renders the majority of patients dependent on chronic red blood cell transfusions. In a study conducted by the Mayo Clinic, within a year of diagnosis, 58% of patients with MF had severe anemia, defined as hemoglobin levels of less than 10 g/dL, and 46% were transfusion-dependent, meaning they required regular transfusion therapy, as shown below. Moreover, existing treatments, such as erythropoiesis-stimulating agents, or ESAs, androgens, corticosteroids, immunomodulators, and splenectomy, are generally viewed as providing minimally effective or inconsistent results, are associated with safety concerns, and do not directly target hepcidin. This is in contrast to the effects observed in a recently published study of a hepcidin-targeted agent conducted in patients with advanced, transfusion-dependent myelofibrosis. In this clinical trial, a partial reduction of hepcidin levels led to approximately 85% of patients having lower transfusion requirements, 41% of patients becoming transfusion independent, increased hemoglobin and improved markers of iron homeostasis.
Currently, patients with MF are treated with JAK inhibitors approved to treat intermediate or high risk MF, including ruxolitinib and fedratinib, which reduce splenomegaly and other symptoms, but typically worsen anemia to the point that patients frequently discontinue treatment.
Elevated Hepcidin Levels in Patients with MF
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Anemia of MF is Progressive and Severe
Anemia of Inflammatory Bowel Disease
IBD, which includes Crohn’s disease and ulcerative colitis, is characterized by chronic inflammation of the gastrointestinal tract. IBD is estimated to affect more than two million people in North America and is associated with numerous symptoms and complications, with the most common being anemia, which can be caused by anemia of inflammation, iron deficiency, and/or blood loss. Anemia has been found to occur in up to 74% of hospitalized IBD patients. Anemia of inflammation is driven by low iron availability from elevated hepcidin levels. Iron deficiency in IBD is caused by inadequate intake, malabsorption (including duodenal involvement and surgical removal), and chronic blood loss by mucosal ulcerations. There is no directed treatment option for anemia of inflammation beyond improving the disease status of the underlying IBD. Iron supplementation can correct iron deficiency and improve anemia due to low total body iron. IBD-associated anemia is associated with a significant decrease in quality of life and with clinical symptoms such as chronic fatigue, dizziness, reduced exercise tolerance, pale skin, nails, conjunctiva, and fainting. However, despite these numerous adverse symptoms, anemia of IBD remains undertreated.
Our Solution: DISC-0974, an Anti-HJV Monoclonal Antibody
DISC-0974 is designed to be an injectable, selective monoclonal antibody targeting HJV, a co-receptor required for hepcidin expression. In multiple preclinical studies, we have demonstrated that DISC-0974 suppressed endogenous production of hepcidin and, as a consequence, increased serum iron levels. Based on this early confirmation of its mechanism, we believe DISC-0974 has the potential to treat a wide range of anemias associated with inflammatory diseases where hepcidin levels are pathologically elevated and serum iron levels for erythropoiesis are restricted. Based on data from our IND-enabling studies and our completed Phase 1 clinical trial, we are developing DISC-0974 as a once-monthly, subcutaneous injection.
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Hemojuvelin Has a Critical and Specific Role for Hepcidin Regulation and Homeostasis
HJV, also called repulsive guidance molecule-c, is a cell surface co-receptor that is primarily expressed in the liver and other tissues with a significant role in iron metabolism, such as skeletal muscle, and is critical for hepcidin production. Signaling through the HJV pathway involves a complex of ligands of the TGF-b superfamily (BMP2/4/6) and other receptors (ALK2/3/6) that induce SMAD phosphorylation and hepcidin (HAMP gene) expression, as shown below. Many components of the BMP signaling pathway are expressed in tissues throughout the body and participate in a range of biological processes, including bone formation and immune cell production. As a result, therapeutic efforts to control hepcidin by targeting the ALK receptors or BMP ligands may affect other tissues and result in off-target side effects. However, based on the phenotype caused by the genetic loss of function of HJV in rodents and humans, we believe that the role of HJV is restricted to iron homeostasis and hepcidin expression, and therefore, we believe that targeting HJV has the potential to result in an improved risk-benefit profile as compared to targeting other members of the BMP pathway.
Hemojuvelin is a Critical and Specific Target for Hepcidin Expression
The importance of HJV in hepcidin expression and iron homeostasis was established through genetic studies in both animals and humans. Specifically, mutations that result in a partial or complete lack of HJV result in significantly reduced hepcidin production and are phenotypically indistinguishable from loss-of-function mutations in hepcidin itself. For example, in a study in mice conducted by a third-party, a knockout of the HJV gene resulted in significantly reduced hepcidin levels in untreated animals as well as in animals challenged with LPS, an inflammatory stimulus, as compared to mice with a functional HJV gene, as shown below.
HJV Gene Knockout in Mice Resulted in Significantly Reduced Hepcidin Levels
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In addition, mutations in the HJV gene in humans markedly reduce hepcidin expression in the liver and result in juvenile hemochromatosis, the most severe form of diseases of iron overload. This genetic evidence suggests that the function of HJV is specific to hepcidin and iron regulation. We believe this specificity is an important attribute in selecting HJV as a target and may result in an improved therapeutic outcome by avoiding unwanted side effects that can result from systemic changes in TGF-b superfamily signaling, such as changes in bone mineral density and immune function. By targeting HJV to reduce hepcidin production, we believe that DISC-0974 has the potential to normalize serum iron levels and restore the production of red blood cells, thereby addressing a key underlying driver of anemia of inflammatory diseases.
Completed Phase 1 Clinical Trial
In July 2021, we initiated a first-in-human, Phase 1, single ascending dose, randomized, double-blind, placebo-controlled clinical trial of DISC-0974 in healthy volunteers to evaluate safety, tolerability, PK, and PD markers such as hepcidin, serum iron levels, TSAT and measures of erythropoiesis. In the initial cohort of the Phase 1 trial, DISC-0974 was administered intravenously. Subsequent cohorts were dosed with DISC-0974 by subcutaneous administration, which has been shown to be comparable and well-tolerated as compared to intravenous administration in preclinical studies. The trial design is summarized in the figure below.
DISC-0974 Phase 1 Clinical Trial Design
We have completed this Phase 1 clinical trial. Data from the Phase 1 clinical trial showed an acceptable tolerability profile and evidence of target engagement and iron mobilization and augmented erythropoiesis.
Specifically, in this Phase 1 study, a single dose of DISC-0974 resulted in rapid, dose-dependent and sustained decrease in serum hepcidin and a corresponding, robust increase in measures of circulating iron. This included more than a doubling of transferrin saturation from baseline at the highest dose level (56 mg SC). Changes in serum iron also corresponded with markers of iron mobilization and erythropoiesis, including decreased ferritin levels, increased reticulocyte hemoglobin, and increased mean corpuscular hemoglobin. These findings are consistent with the mechanism of action of DISC-0974.
Notably, at the 56 mg SC dose level, a single administration of DISC-0974 resulted in a statistically significant improvement in hemoglobin compared to placebo (+1.1 g/dL, p=0.009) at Day 42 and a marked increase in red blood cell count. DISC-0974 was well-tolerated at all dose levels with no serious or severe adverse events, no adverse events leading to study withdrawal, and no adverse event greater than Grade 1. Plasma exposure was dose-related in the 14 to 56 mg SC range and effects were observed through 28 days post-dose, indicating a sustained and potentially clinically meaningful duration of action. These findings were presented at the 2022 EHA meeting in June 2022 and the 2022 ASH annual meeting.
Ongoing Phase 1b/2 Clinical Trial in Patients with Anemia of MF
In June 2022, we initiated an open-label, multi-center, Phase 1b/2 trial to evaluate the safety, tolerability, and efficacy of DISC-0974 in patients with anemia of MF. The study endpoints include hepcidin levels, serum iron and markers of iron mobilization and measures of anemia benefit such as hemoglobin, reductions in transfusion burden and transfusion independence (TI) rate. The study allows enrollment of patients receiving stable background therapy, including JAK inhibitors. The study is being conducted in two parts:
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Phase 1b (Dose-Escalation): Ascending, monthly doses of DISC-0974 administered for six months to patients with anemia of MF, (Hb levels < 10 g/dL,), where a dose level is selected based on optimal increases in hemoglobin and serum iron;
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Phase 2 (Expansion Stage): Multiple doses of DISC-0974 administered once-a-month at the dose level selected from the Phase 1b portion of the study to patients with anemia of MF who are transfusion dependent or non-transfusion dependent, generally defined according to the baseline transfusion burden in a 12-week period.
Interim data from the Phase 1b part of this trial was first presented at the ASH annual meeting in December 2023, with additional interim data presented in June 2024 and additional analyses presented in December 2024 and June 2025. Of the 35 enrolled patients, data from 32 evaluable participants in the five dose cohorts (14 mg, 28 mg, 50 mg, 75 mg and 100 mg) were presented as of an October 17, 2024 data cutoff date. Two participants withdrew early from the trial due to an inadequate response, and two participants were not considered evaluable for efficacy due to incomplete transfusion data entry as of the October 17, 2024 data cutoff. Thirteen participants were taking concomitant JAK inhibitors. Twenty-two of the evaluable participants were non-transfusion dependent receiving no transfusions (nTD), five were transfusion dependent with one to two transfusions within a 12-week period at baseline (TD Low), and five were transfusion dependent with three to 12 transfusions within a 12-week period at baseline (TD High). DISC-0974 was administered subcutaneously at 14 mg (n=1), 28 mg (n=7), 50 mg (n=12), 75 mg (n=9), or 100 mg (n=6) every four weeks for up to six treatments; patients can remain on continuation treatment after the first six doses. Results demonstrated consistent, substantial decreases in hepcidin reaching >75% from baseline and corresponding increases in serum iron across patients, which translated to increased levels of reticulocyte hemoglobin and hemoglobin, as well as reduced levels of zinc protoporphyrin, a marker of iron-restricted erythropoiesis. 68% of baseline nTD patients achieved a hemoglobin increase of ≥1.5 g/dL during the study period and 50% had sustained mean increases for ≥12 weeks. 100% of TD Low patients achieved a ≥50% reduction in transfusion requirement, and 80% of TD Low patients achieved transfusion independence, defined as no blood transfusions, over a 16-week period. 60% of TD High patients achieved a ≥50% reduction in transfusion requirement, and 40% of evaluable TD High patients achieved transfusion independence over a 12-week period. 54% of patients receiving concomitant JAK inhibitor therapy achieved a major hematologic response.
DISC-0974 Anemia of MF Phase 1b Clinical Trial Results: Pharmacodynamics
DISC-0974 was generally well-tolerated at all evaluated dose levels. Diarrhea was the only adverse event that was considered related to DISC-0974 and reported in two or more subjects. The majority of adverse events were not considered related to DISC-0974.
In December 2024, we initiated RALLY-MF, the open-label Phase 2 portion of this clinical trial to evaluate the safety, tolerability and efficacy of DISC-0974 in patients with anemia of MF. The Phase 2 study design is summarized below.
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RALLY-MF Trial Design: Open-Label Phase 2 Clinical Trial of DISC-0974 in Patients with Anemia of MF
*Patients carried over from Phase 1b: nTD n=8, TD (Low + High) n=4
Initial data from the Phase 2 part of this trial was first presented at the ASH annual meeting in December 2025. Of the 47 patients enrolled as of the October 16, 2025 cutoff date, data from 34 evaluable participants were presented. Eighteen of the evaluable participants were taking concomitant JAK inhibitors. Twenty-four of the evaluable participants were non-transfusion dependent receiving no transfusions (nTD), seven were transfusion dependent with one to two transfusions within a 12-week period at baseline (TD Low), and three were transfusion dependent with three to 12 transfusions within a 12-week period at baseline (TD High). DISC-0974 was administered subcutaneously at 50 mg every four weeks for up to six treatments. Initial results demonstrated consistent, substantial decreases in hepcidin reaching >75% from baseline and corresponding increases in serum iron across patients. 63% of baseline nTD patients achieved a hemoglobin increase of ≥1.0 g/dL for ≥12 weeks (an overall response) and 50% had an increase of ≥1.5 g/dL for ≥12 weeks (a major response). 71% of TD Low patients achieved transfusion independence, defined as no blood transfusions, over a 16-week period. 67% of TD High patients with at least 85 days on study achieved a ≥50% reduction in transfusion requirement, and initial data for an additional n=3 TD High patients was trending towards a major response of transfusion independence for ≥12 weeks. 50% of patients receiving concomitant JAK inhibitor therapy achieved a major hematologic response. Dosing with DISC-0974 was associated with improvements in FACIT-Fatigue scores in nTD and TD Low participants.
Initial RALLY-MF Phase 2 Clinical Trial Results: Effects on Hepcidin and Iron Serum, and Hematologic Response
DISC-0974 was generally well-tolerated. Diarrhea and urinary tract infections, neither considered serious, were the only adverse events that were considered related to DISC-0974 and reported in two or more subjects. The majority of adverse events were not considered related to DISC-0974.
We expect to report topline data from our RALLY-MF Phase 2 trial in 2026, which, if positive, are expected to support discussions with regulatory agencies on the potential regulatory path for DISC-0974 in anemia of MF.
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Ongoing Phase 2 Clinical Trial in Patients with Anemia of Inflammatory Bowel Disease
We initiated a Phase 2 clinical trial of DISC-0974 in patients with IBD and anemia in the first quarter of 2026. The study design is below. We are also planning exploratory studies in additional patient populations with anemia of chronic disease.
Phase 2 Clinical Trial of DISC-0974 in IBD Patients with Anemia
Completed Phase 1b Clinical Trial in Patients with Non-Dialysis Dependent Chronic Kidney Disease (NDD-CKD)
In February 2023, we initiated a Phase 1b clinical trial to evaluate the safety, tolerability and efficacy of DISC-0974 in patients with CKD who are not receiving dialysis and are anemic. The study consisted of two parts: a randomized, placebo-controlled, single-ascending dose stage, where a dose level was selected based on optimal increases in serum iron; followed by an expansion stage where patients received multiple doses of DISC-0974 at the selected dose level. The study endpoints include hepcidin levels, serum iron and markers of iron mobilization and measures of anemia benefit such as hemoglobin.
Phase 1b Clinical Trial of DISC-0974 in NDD-CKD Patients with Anemia
Interim data from the SAD portion of this trial were presented in December 2023 and October 2024. Additional data, including data from the multiple dose portion of this trial, were presented in October 2025. In this trial, DISC-0974 was generally well-tolerated and results demonstrated substantial decreases in hepcidin, increases in iron, and improvements in markers of erythropoiesis.
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However, meaningful hemoglobin increases were observed in only a subset of patients, which were in part driven by those with higher baseline erythropoietin, or EPO, levels. As such, DISC-0974 demonstrated engagement of mechanism in anemia of NDD-CKD but with variable effects on hemoglobin. We are assessing options for our DISC-0974 NDD-CKD program on the basis of this data.
Our Second Hepcidin Suppression Program: DISC-0998
We are also developing a next-generation, long-acting antibody that targets hepcidin suppression, which efforts include our preclinical product candidate DISC-0998, an anti-HJV monoclonal antibody in-licensed from AbbVie. DISC-0998 is designed to be a highly selective anti-HJV mAb with an adapted Fc region to increase PK half-life. In preclinical studies DISC-0998 demonstrated biological activity, low immunogenicity potential, and desirable PK and PD properties.
A dose response PK/PD study of DISC-0998 in NHPs demonstrated that it had a lower clearance (~30 - 40%), higher volume of distribution (~30 - 70%), and longer half-life (~2 times), which translated to a longer duration of PD effects compared to DISC-0974. A single dose of DISC-0998 resulted in sustained elevation of serum iron levels. If these data are confirmed in humans, it would suggest the potential for an infrequent dosing regimen (such as potentially once every 2 or 3 months). We expect that such a dosing regimen would be perceived as convenient by patients and promote compliance.
We are continuing IND-enabling activities for this next-generation hepcidin suppression program.
Our Hepcidin Induction Program
We are also focused on developing product candidates designed to increase hepcidin levels and decrease serum iron levels to address a range of diseases where restricting iron would be beneficial, such as erythrocytosis of PV and diseases of iron overload, including SCD. Our lead hepcidin induction program, DISC-3405, is a monoclonal antibody that is designed to target TMPRSS6. TMPRSS6 proteolytically degrades HJV in liver cells, as shown below. Inhibitors of TMPRSS6 are expected to increase HJV levels and thereby increase the expression of hepcidin. By inhibiting TMPRSS6, our compounds are designed to increase hepcidin production and, in turn, restrict iron availability. We selected TMPRSS6 as our target because the effects of reducing TMPRSS6 levels have been genetically confirmed in both animal knockout studies and in patients with iron-refractory iron deficiency anemia who lack fully functional genes encoding TMPRSS6.
TMPRSS6 Suppresses Hepcidin by Degrading HJV
Polycythemia Vera
PV is a chronic and rare myeloproliferative neoplasm characterized by the overproduction of red blood cells and increased red cell mass. It is frequently caused by acquired mutations of the JAK2 gene that drive abnormal proliferation of red blood cells. The increased number of red blood cells alters the viscosity of blood, causing it to thicken and placing patients at an increased risk of cardiovascular and thromboembolic events, such as heart attack and stroke. The prevalence of PV is estimated to be 44 to 57 cases per 100,000 persons, with approximately 150,000 patients with PV in the United States and with prevalence estimates in Europe ranging from 10 to 50 cases per 100,000 persons. PV tends to primarily affect individuals over 60 years old.
Current management of PV centers around depleting the number of red blood cells to maintain a patient’s hematocrit (a measure of red blood cell mass) below 45%, the target threshold recommended by the National Comprehensive Cancer Network to reduce the
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risk of cardiovascular or thromboembolic events. Most patients receive low-dose aspirin and chronic therapeutic phlebotomy to physically remove blood and iron to limit erythropoiesis. However, most patients fail to achieve their target hematocrit levels and remain at risk for thrombosis and other complications. Moreover, phlebotomy causes discomfort and inconvenience for patients as well as side effects such as headaches, ringing in the ears, dizziness, and, over time, iron deficiency. Cytoreductive chemotherapy is recommended for patients at higher risk of thrombosis, including those who fail to meet their hematocrit threshold, or conversion to leukemia. These include hydroxyurea, interferons, or ruxolitinib, marketed as Jakafi, each of which are associated with side effects and can affect multiple cell types. There is currently no oral, non-cytoreductive option for the treatment of PV, which we believe would be beneficial for both low and high-risk patients.
Sickle Cell Disease
SCD is an inherited blood disorder caused by mutations in hemoglobin that enable the hemoglobin to form long polymeric chains under certain conditions such as low oxygenation, or deoxygenation. Polymerization of this irregular hemoglobin results in red blood cells taking on a sickle shape, causing them to aggregate and obstruct small blood vessels, as well as hemolyze and release toxic metabolites, which collectively can restrict blood flow to organs resulting in pain, cell death and organ damage. We estimate that the prevalence of SCD is approximately 100,000 individuals in the United States, and greater than three million individuals worldwide. Red blood cell deoxygenation is modulated by several factors, including the levels of 2,3-diphosphoglycerate, or 2,3-DPG, which is found to be elevated in sickle cell patient red blood cells. Current treatment strategies focus on managing and preventing acute red blood cell sickling, and include hydroxyurea, L-glutamine and blood transfusions, as well as recently approved therapies such as Adakveo®, Casgevy®, and Lfygenia®.
Our Solution: DISC-3405 (MWTX-003), an anti-TMPRSS6 monoclonal antibody
In January 2023, we in-licensed MWTX-003 and other related molecules from Mabwell. In the Disc compound catalog, MWTX-003 is named DISC-3405. DISC-3405 is a monoclonal antibody designed to inhibit TMPRSS6, a serine protease that degrades HJV, a receptor required for hepcidin expression. TMPRSS6 plays a critical and specific function in iron metabolism by limiting the production of hepcidin. By inhibiting TMPRSS6, DISC-3405 has been shown in preclinical studies to increase endogenous production of hepcidin and reduce serum iron levels. This mechanism has been validated by human genetics, where patients with mutations in TMPRSS6 develop elevated hepcidin levels and an iron restrictive phenotype. In addition, iron restriction has been recently validated as a potential approach to treat PV. In Phase 2 and Phase 3 clinical trials conducted by a third-party, a peptide hepcidin mimetic administered weekly by subcutaneous injection lowered iron availability and reduced hematocrit in patients with PV, resulting in a substantial reduction in requirements for phlebotomy and improvements in disease symptoms. In SCD, iron depletion has been shown in open-label case series in SCD patients to reduce hemolysis and reduce some SCD complications. The rationale for limiting iron availability for red blood cell production rests in the relationship between sickle hemoglobin concentration inside red blood cells and the tendency for the sickle hemoglobin to polymerize and cause hemolysis, which is an initial step in SCD pathophysiology. By restricting iron availability through hepcidin induction, sickle hemoglobin concentration, and consequently abnormal sickle hemoglobin polymerization and hemolysis, is anticipated to be reduced and potentially lead to improved red blood cell health and fewer clinical complications of SCD. We are initially focused on developing our anti-TMPRSS6 programs as a potential treatment for PV and SCD, with plans to expand development to encompass additional diseases of iron overload and other conditions where restriction of iron would have therapeutic benefit.
Preclinical Data
Preclinical studies of MWTX-003 have demonstrated that TMPRSS6 inhibition with a monoclonal antibody can induce hepcidin expression and consequently restrict iron availability. Specifically, preclinical studies have demonstrated:
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Dose-dependent induction of endogenous hepcidin production in rodent and NHP studies;
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Increases in hepcidin, reductions in serum and liver iron, and increases in red blood cells in a murine model of beta-thalassemia; and
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Reductions in iron and hematocrit in a murine model of PV.
Across several preclinical studies in both rodents and non-human primates, treatment with MWTX-003 was shown to increase hepcidin production and reduce serum iron levels. For example, in the below experiment in NHPs, treatment with a single, intravenously administered 30 mg/kg or 150 mg/kg dose of MWTX-003 resulted in deep and sustained suppression of serum iron levels for at least 3 weeks.
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Treatment with MWTX-003 resulted in deep and sustained suppression of serum iron levels in normal non-human primates
The potential efficacy of MWTX-003 was also assessed in HbbTh3/+ mice, an established, genetic rodent model of beta-thalassemia. In this study, mice with mutations in the Hbb gene leading to underproduction of beta-globin genes were treated with 10 mg/kg MWTX-003 once every 3 days for 4 weeks which resulted in recapitulated features of beta-thalassemia such as ineffective erythropoiesis, iron overload and enlarged spleens. Treated mice showed decreased serum iron levels and liver non-heme iron, reduced splenomegaly and improved ineffective erythropoiesis compared to control. Additionally, a study was conducted assessing the efficacy of MWTX-003 in PV using a Jak2V617F bone marrow transplantation mouse model. In these mice, treatment with MWTX-003 at 2-10 mg/kg every 4 days for 3 weeks led to significantly increased serum hepcidin with reduced hematocrit levels, red blood cell counts, and hemoglobin concentration that were comparable to that of wildtype control mice.
Completed Phase 1 Clinical Trial
We initiated a Phase 1 clinical trial of DISC-3405 in healthy adult volunteers in October 2023. Interim data was presented from the SAD portion of the Phase 1 clinical trial in June 2024. We presented data from the MAD portion of the Phase 1 healthy volunteer study of DISC-3405 in December 2024. In the SAD portion of this trial, healthy males and females ages 18 to 65 were given a single dose of placebo (n=10) or DISC-3405 at 75 mg intravenously (IV) (n=6), 37.5 mg subcutaneously (SC) (n=6), 75 mg SC (n=6), 150 mg SC (n=6), or 300 mg SC (n=6). The MAD portion of this trial included placebo (n=4), 75 mg SC (n=6), and 150 mg SC (n=6) cohorts dosed every four weeks for a total of two doses.
In this trial, DISC-3405 produced dose-related increases in serum hepcidin with corresponding reductions in serum iron across all dose levels. DISC-3405 also resulted in deep reductions in serum iron (ranging maximally from 50% to 80% from baseline) that were sustained and support a once-monthly SC dosing regimen. In addition, single and repeat dosing of DISC-3405 demonstrated meaningful reductions in hematologic parameters, including reticulocyte hemoglobin, hemoglobin, and hematocrit.
DISC-3405 Phase 1 Healthy Volunteers Study: Hepcidin, Iron and Ferritin
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DISC-3405 Phase 1 Healthy Volunteers Study: Hematologic Response
DISC-3405 was generally well-tolerated at all evaluated dose levels, with no serious adverse events, no adverse events greater than Grade 2, or adverse events leading to study withdrawal.
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RESTORE-PV: Ongoing Phase 2, Open-Label Clinical Trial of DISC-3405 in Participants with PV
In the first half of 2025, we initiated RESTORE-PV, a Phase 2, open-label clinical trial of DISC-3405 in participants with PV. This 52-week study is designed to enroll up to 60 participants with PV from sites in the United States. The aims of the study are to assess safety and tolerability, PK, pharmacodynamics, and therapeutic effect of DISC-3405 on PV disease control as evidenced by phlebotomy requirements. The main efficacy endpoints of the study include proportion of participants achieving therapeutic response, defined as absence of phlebotomy eligibility; number of phlebotomies during the treatment period; and proportion of participants with hematocrit HCT values of less than 45% throughout the study.
RESTORE-PV Phase 2 Clinical Trial Design
We expect to report initial data from our RESTORE-PV trial in the second half of 2026.
Ongoing Phase 1b Clinical Trial of DISC-3405 in Patients with SCD
We also initiated a Phase 1b, open-label clinical trial of DISC-3405 in patients with SCD in October 2025, with initial data expected in the second half of 2026, and plan to explore the role of therapeutic iron restriction in other indications.
Manufacturing
We do not own or operate, and currently have no plans to establish, any manufacturing facilities. We rely on, and expect to continue to rely on for the foreseeable future, third-party contract development and manufacturing organizations, or CDMOs, to produce our product candidates and preclinical materials, including bitopertin, DISC-0974, DISC-0998, DISC-3405 and any candidates arising from our research programs, for preclinical and clinical use. We plan to continue to rely on third-party CDMOs for any future trials as well as for the commercial manufacture of our product candidates and preclinical materials, if approved. In addition, we contract with additional CDMOs to package, label, and distribute drug product for preclinical and clinical use.
Some of our product candidates are biological products. Manufacturing biologics can be particularly complex, especially in large quantities. Biologic products must be made consistently and in compliance with a clearly defined manufacturing process. We require that our CDMOs produce bulk drug substances and finished drug products in accordance with current Good Manufacturing Practices, or cGMPs, and all other applicable laws and regulations. We have assembled a team of experienced employees and external consultants to provide the required technical, quality, and regulatory oversight of our CDMOs and have implemented a comprehensive plan for regular audits of our CDMOs. We maintain agreements with our manufacturers that include confidentiality and intellectual property provisions to protect our proprietary rights related to our product candidates.
We obtain supplies of our product candidates from single-source CDMOs on a purchase order basis and do not currently have any long-term supply arrangements in place. While any reduction or halt in supply of our product candidates from these CDMOs could limit our ability to develop our product candidates until we find a qualified replacement CDMO, we have procured or are in the process of procuring sufficient supply to support our ongoing clinical trials. In addition, we believe that we can identify and establish additional CDMOs to provide API and finished drug product without significant disruption to our business or clinical development timelines. As our pipeline programs expand and we build new process efficiencies, we expect to continually evaluate this strategy with the objective of satisfying demand for registration trials and, if approved, the manufacture, sale, and distribution of commercial products.
A commercial-scale production process has been designed for bitopertin, including a four-step chemical synthesis and an optimized oral formulation. To support the commercial launch of bitopertin, if approved, we are in the process of establishing a validated drug substance and drug product manufacturing process at a CDMO.
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Competition
The biotechnology and pharmaceutical industries are characterized by rapidly advancing technologies, intense competition, and a strong emphasis on intellectual property. While we believe that our product candidates, preclinical programs, scientific capabilities, know-how, and experience provide us with competitive advantages, we compete in a highly competitive industry and face significant competition from many sources, including pharmaceutical and biotechnology companies, as well as academic institutions, governmental agencies, and private and public research institutions worldwide. Many of our competitors, either alone or through collaborations, have significantly greater financial resources and expertise in research and development, manufacturing, preclinical testing, conducting clinical trials, obtaining regulatory approvals, and marketing approved products than we do. Mergers and acquisitions in the pharmaceutical and biotechnology industries may result in even more resources being concentrated among a smaller number of our competitors. Smaller or early-stage companies may also prove to be significant competitors, particularly through collaborative arrangements with large and established companies. These companies also compete with us in recruiting and retaining qualified scientific and management personnel, establishing clinical trial sites, and recruiting patients in clinical trials, as well as in acquiring technologies complementary to, or necessary for, our programs. As a result, our competitors may discover, develop, license, or commercialize products before or more successfully than we do.
We face competition more specifically from companies that discover, develop, and market therapies for the treatment of hematologic diseases, including porphyrias and anemia associated with inflammatory diseases. There are many other companies, including large biotechnology and pharmaceutical companies, that have commercialized or are developing therapies for the same diseases that we are targeting with our product candidates. These companies include, but are not limited to, Agios Pharmaceuticals, Inc., Akebia Therapeutics, Inc., Amgen, Inc., Astellas Pharma, Inc., Bristol-Myers Squibb Company, FibroGen, Inc., GlaxoSmithKline, plc, Incyte Corporation, Ono Pharmaceuticals, Inc., Keros Therapeutics, Inc., Merck & Co., Inc., Otsuka Pharmaceutical Co., Ltd. and Vifor Pharma AG, among others.
We are developing bitopertin, our lead product candidate in our heme biosynthesis modulation portfolio, for the treatment of EPs. If approved, bitopertin will face competition from melanocortin-1 receptor agonists, including afamelanotide, a subcutaneously implanted therapy that is approved in the U.S. and other territories and marketed as Scenesse by Clinuvel. Dersimelagon, an oral MC1R agonist, recently completed a Phase 3 trial conducted by Mitsubishi Tanabe Pharma Corporation for the treatment of EPP or XLP. Portal Therapeutics, a subsidiary of BridgeBio Pharma, Inc., is currently testing in a first-in-human Phase 1 clinical study in healthy volunteers and a Phase 2a study in adults with EPP, PORT-77, an ABCG2 inhibitor, with a development goal to reduce plasma PPIX in EPP. In addition, there are other potential treatments currently in the discovery stages of development that may become competitors in the future. These therapies include, but are not limited to, gene therapies, heme biosynthesis modulators that target GlyT1 or other enzymes in the heme biosynthesis pathway, and molecules that target porphyrin export.
Bitopertin is a selective inhibitor of GlyT1 that we are developing to treat porphyrias and other hematologic diseases. GlyT1 inhibition has been pursued in the past as an approach to treat schizophrenia. We are aware that Boehringer Ingelheim conducted a Phase 3 clinical study of BI 425809 (iclepertin), a GlyT1 inhibitor, for the improvement of cognition in patients with schizophrenia that failed to meet its primary endpoint. Other companies have also had research programs designed to inhibit GlyT1 as a treatment for schizophrenia, but to our knowledge, all of these have been discontinued at various stages of development. These include PF-03463275 (Pfizer Inc.), LY2365109 (Eli Lilly and Company), ORG25935 (Organon & Co.), ALX5407 (NPS Pharmaceuticals, Inc., now Shire plc), ASP2535 (Astellas Pharma Inc.) and others. We believe bitopertin has an optimal profile for development as a potential treatment for EP. However, we recognize that other companies may choose to develop a novel GlyT1 inhibitor or repurpose an existing one; if successfully developed as a treatment for EPs, such a program would be a potential competitor to bitopertin.
We are also developing DISC-0974, our lead program in our hepcidin suppression portfolio, for the treatment of anemia caused by inflammatory diseases, including MF and IBD. For the treatment of anemia of MF, there are no approved therapies, but several classes of drugs are used off-label, including ESAs, such as Procrit (Janssen Pharmaceuticals, Inc.), Epogen and Aranesp (Amgen, Inc.), and Mircera (Roche), corticosteroids, and androgenic hormones, such as danazol. There are also multiple classes of drugs in development for the treatment of anemia. For example, multiple erythroid maturation agents are in development, such as luspatercept, which recently completed a myelofibrosis Phase 3 trial by Bristol-Myers Squibb, and KER-050, which is in a Phase 2 trial by Keros, Inc. In addition, GlaxoSmithKline has developed Ojaara (momelotinib), a JAK2 kinase inhibitor that lowers hepcidin by inhibiting ALK2 (a kinase that is similar to but less specific than HJV), which was approved to treat myelofibrosis patients with anemia.
For the treatment of anemia of IBD, there are several approved iron therapies, including oral irons such as Accrufer (Shield Therapeutics) and IV irons such as Monoferric (Pharmacosmos Therapeutics) and Injectafer (Daiichi Sankyo). We are not aware of any other products in development for anemia of IBD. Clinical data from IBD-directed therapies show that anemia can sometimes be addressed by decreasing inflammation of the underlying IBD process.
We are developing DISC-3405, an anti-TMPRSS6 monoclonal antibody designed to induce hepcidin production and restrict serum iron levels, with an initial focus on PV and SCD. There are several therapies in development that are also designed to increase hepcidin production or mimic hepcidin activity, such as hepcidin mimetics, TMPRSS6 inhibitors, and ferroportin inhibitors. These
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are in various stages of development by companies, including Regeneron, Silence Therapeutics plc, Ionis Pharmaceuticals, Inc., Rallybio, Agios Pharmaceuticals, Inc., and CSL Vifor, among others. In particular, rusfertide, an investigational hepcidin mimetic peptide therapeutic for PV, recently completed a Phase 3 clinical trial conducted by Protagonist Therapeutics, Inc. We may also face competition from therapies that are currently marketed or in development that affect pathways unrelated to hepcidin, including growth and differentiation factor-based therapies, cytoreductive therapies, and chemotherapeutic agents, among others. For the treatment of SCD, there are two gene therapy products that were approved in 2023, Casgevy (Vertex Pharmaceuticals) and Lyfgenia (Bluebird Bio). Additionally, hydroxyurea is approved to reduce the frequency of painful crises and reduce the need for blood transfusions in SCD patients with moderate to severe painful crises. Adakveo (Novartis) is approved for the reduction of vasoocclusive crises and Endari (Emmaus Medical Inc) is approved to reduce acute complications of SCD. The competitive pipeline for SCD is crowded with multiple drugs in development.
We could see a reduction or elimination of our commercial opportunity if our competitors develop and commercialize products that are safer, more effective, have fewer or less severe side effects, are more convenient to administer, are less expensive, or receive a more favorable label than any products that we may develop. Our competitors also may obtain FDA or other regulatory approval for their products more rapidly than we may obtain approval for our products, which could result in our competitors establishing a strong market position before we are able to enter the market. The key competitive factors affecting the success of all of our product candidates, if approved, are likely to be their efficacy, safety, convenience, price, the level of generic competition, and the availability of reimbursement from government and other third-party payors.
Collaborations and License Agreements
2019 Exclusive License Agreement with AbbVie Deutschland GmbH & Co. KG
In September 2019, we entered into an exclusive license agreement with AbbVie. Under the license agreement with AbbVie, or the AbbVie Agreement, we obtained an exclusive, worldwide license, with the right to sublicense to commercial pharmaceutical and biopharmaceutical companies (subject to AbbVie’s prior consent or pre-authorization, except with respect to our affiliates), under certain patents and technical information of AbbVie, to make, have made, use, have used, sell, have sold, lease, have leased, import, have imported or otherwise transfer licensed products for all therapeutic, diagnostic and prophylactic uses in humans and animals, excluding uses in neuroscience and neurology. The anti-hemojuvelin antibodies, DISC-0974 and DISC-0998, are licensed products under the AbbVie Agreement. We are required to use commercially reasonable efforts to develop and commercialize at least one licensed product in certain major markets and to maximize net sales of licensed products in certain major markets.
Under the terms of the AbbVie Agreement, we made an initial license payment to AbbVie of $0.6 million. Additionally, we are required to pay certain development milestone payments for each licensed product, which milestone payments are up to $18.0 million in the aggregate, certain commercial milestone payments for each licensed product, which milestone payments are up to $45.0 million in the aggregate, and certain milestone payments based on the level of net sales of all licensed products worldwide, which milestone payments are up to $87.5 million in aggregate. In January 2025, we made a milestone payment of $3.0 million upon the first administration to a patient in the Phase 2 clinical trial of DISC-0974. We are also obligated to pay a royalty on net sales of licensed products at a low-single digit rate. The royalty rates are subject to up to a high first decile percentage reduction for lack of a valid claim on a country-by-country basis. See “Business-Intellectual Property-Iron Homeostasis Portfolio” for additional information concerning the intellectual property related to the AbbVie Agreement.
The obligation to pay royalties under the AbbVie Agreement expires on a licensed product-by-licensed product and country-by-country basis upon the later of expiry of (a) (i) the last valid claim of the licensed patents that cover such licensed product or the exploitation thereof in such country or (ii) the last-to-expire improvement patent in such country, whichever is later, (b) the expiration of regulatory exclusivity in such country, and (c) ten years from the first commercial sale of such product in such country.
The AbbVie Agreement expires upon expiry of the last remaining royalty obligation for the last licensed product. Under the AbbVie Agreement, either party may terminate the agreement upon the other party’s uncured material breach or insolvency, and AbbVie may also terminate the agreement upon our failure to conduct any relevant material development or commercialization activity in a 12-month period, or, to the extent AbbVie is permitted pursuant to applicable law, a challenge by us of the licensed patents. We may terminate the agreement for any reason upon specified prior written notice to AbbVie.
In connection with the AbbVie Agreement, we also entered into a stock purchase agreement with AbbVie in September 2019, pursuant to which we agreed to issue 4,336,841 shares of our common stock to AbbVie, with 2,295,174 shares vesting immediately and 2,041,667 shares subject to a performance condition tied to the second and third subsequent closings of our Series A Preferred Stock financing. During the year ended December 31, 2020, the performance conditions were met and the remaining 2,041,667 shares vested. At the closing of the merger, shares of our common stock held before the merger were exchanged for shares of common stock in the combined publicly-traded company based on an exchange ratio of 0.1096.
2021 Exclusive License Agreement with F. Hoffmann-La Roche Ltd and Hoffmann-La Roche Inc.
In May 2021, we entered into a license agreement, or the Roche Agreement, with F. Hoffmann-La Roche Ltd. and Hoffmann-La Roche Inc., or together, Roche, pursuant to which Roche granted us an exclusive and sublicensable (subject to Roche’s consent, not
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to be unreasonably withheld, except with respect to affiliates) worldwide license under certain of Roche’s patent rights and know-how to develop and commercialize bitopertin, including certain backup compounds and derivatives, in all indications and for all therapeutic and prophylactic uses, except diagnostic use. Roche retained the rights with respect to diagnostic uses and its own internal non-clinical research purposes.
Under the Roche Agreement, Roche has an exclusive right to negotiate a license or purchase of all licensed compounds and products in certain specified circumstances. If we, for a specified period of time following entry into the Roche Agreement or before completion of a Phase 3 clinical trial of a licensed product (whichever is later), intend to enter into a sublicense or assignment of the Roche Agreement granting rights in the U.S., China or one or more major EU countries, then Roche will have a specified amount of time to perform diligence and negotiate the applicable license, purchase, or acquisition. If the parties are not able to come to terms during the applicable negotiation period, we are free to enter into the applicable transaction, provided that we may not enter into such a transaction on terms less favorable to us than the terms offered by Roche during a specified period after the conclusion of the negotiation period.
We are required to use commercially reasonable efforts to develop, seek regulatory approval and, on a country-by-country basis where such regulatory approval has been obtained, commercialize at least one licensed product in each such country.
Under the Roche Agreement, we paid Roche an initial license payment of $4.5 million and we are required to pay Roche up to an aggregate of $50.0 million in development and regulatory milestone payments for development and approval in a first indication, up to an aggregate of $35.0 million in development and regulatory milestone payments for development and approval in a second indication. In June 2025, we made a milestone payment of $10.0 million upon the initiation of the first Phase 3 clinical trial with a licensed product in a first indication. The next potential milestone payment is $15.0 million due upon regulatory approval in the United States with a licensed product in a first indication. We will also pay Roche up to an aggregate of $120.0 million based on achievement of certain thresholds for annual net sales of licensed products. We are also obligated to pay a royalty on annual net sales of licensed products at a tiered rate ranging from the high-single digits to the high teens. The royalty rates are subject to a reduction (i) by 25% for lack of a valid claim covering the licensed product generating such sales, and (ii) by 50% for prevalence of generic products (or 25% if there are generic products on the market but there is still a valid claim), in each case on a country-by-country basis. Additionally, royalties are apportioned where licensed compounds are commercialized in combination products.
The obligation to pay royalties under the Roche Agreement expires on a licensed product-by-licensed product and country-by-country basis upon the later of (a) expiry of the last valid claim of the licensed and improvement patents that cover such licensed product in such country, (b) the expiration of regulatory exclusivity in such country, and (c) twelve years from the first commercial sale of such product in such country. The expiry of the last valid claim of the licensed and improvement patents subject to the Roche agreement is currently scheduled to occur in April 2035.
In connection with the Roche Agreement and pursuant to an addendum to the Roche Agreement between the parties executed in December 2021, we agreed to issue to Roche or its affiliates, immediately following the closing of the merger and for no additional consideration, shares of common stock estimated to be approximately 2.85% of the combined company’s issued and outstanding capitalization immediately following the closing of our merger with Gemini Therapeutics, Inc., or Gemini, and our pre-closing financing. Upon completion of the merger, we issued 482,313 shares of common stock to Roche.
The Roche Agreement expires upon expiry of the last remaining royalty obligation for the last licensed product. Under the Roche Agreement, either party may terminate the agreement upon the other party’s uncured material breach or insolvency. We may terminate the agreement for any reason upon specified prior written notice to Roche. In the event the Roche Agreement is terminated for certain causes, if Roche elects to continue development or commercialization of licensed products, certain single-digit royalties may be owed to us in connection with such continued development or commercialization.
2023 Exclusive License Agreement with Mabwell Therapeutics, Inc.
On January 19, 2023, we entered into an exclusive license agreement with Mabwell (a wholly-owned subsidiary of Mabwell (Shanghai) Bioscience Co., Ltd), or the Mabwell Agreement, pursuant to which Mabwell granted us an exclusive and sublicensable license under certain patent rights, know-how, and materials to develop and commercialize antibody products containing Mabwell’s MWTX-001, MWTX-002, and MWTX-003 antibodies, along with limited variants thereof, in all fields of use, in all territories other than Greater China (Mainland China, Hong Kong, Macau and Taiwan) and Southeast Asia (Brunei, Myanmar, Cambodia, Timor-Leste, Indonesia, Laos, Malaysia, Philippines, Singapore, Thailand and Vietnam). We also granted Mabwell an exclusive, sublicensable, royalty-free license under our patents and know-how arising under the Mabwell Agreement to develop and commercialize licensed antibody products in Greater China and Southeast Asia.
Under the Mabwell Agreement, we paid an upfront payment of $10.0 million in March 2023. In addition, we are required to pay certain development and regulatory milestone payments for the licensed antibody products, for up to three indications, up to a maximum aggregate amount of $127.5 million, as well as certain commercial milestone payments for certain licensed antibody product net sales achievements, up to a maximum aggregate amount of $275.0 million. In October 2023, we made a milestone payment of $5.0 million upon the first administration to a patient in the Phase 1 clinical trial for DISC-3405. In September 2025,
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we made a milestone payment of $10.0 million upon the first administration to a patient in a Phase 2 clinical trial for DISC-3405. In February 2026, we completed the first administration to a patient in a Phase 1b clinical trial with a licensed product in a second indication which resulted in milestone payable of $5.0 million. We are further obligated to pay a tiered percentage of revenue that we receive from our sublicensees (excluding revenue that is attributable to net sales on which royalty payments are due), ranging from a low third decile percentage if the sublicense is granted prior to the initiation of a Phase 1 clinical trial of the licensed antibody product, to a low first decile percentage if the sublicense is granted after regulatory approval of the licensed antibody product. No sublicense revenue is due if the sublicense is granted after the first commercial sale of the licensed antibody product.
In addition, we are obligated to pay Mabwell a royalty on annual net sales of all licensed antibody products at a tiered rate ranging from low single-digits to high single-digits, subject to customary royalty reductions for (i) lack of a valid patent claim covering the licensed antibody product generating such sales, (ii) entry of a biosimilar product that equals or exceeds 20% of the total market share of the licensed antibody product, and (iii) a portion of any royalties paid to a third party for patents that claim the composition of matter or method of use of the licensed antibodies. Further, royalties are subject to customary apportionment calculations where the licensed antibodies are commercialized in combination products. The obligation to pay royalties under the Mabwell Agreement expires on a licensed antibody product-by-licensed antibody product and country-by-country basis upon the later of (a) expiration of the last valid patent claim of the licensed patents that cover such licensed antibody product in such country, (b) expiration of regulatory exclusivity for such licensed antibody product in such country, and (c) ten years from the first commercial sale of such licensed antibody product in such country.
Our license grant expires upon expiration of the last remaining royalty obligation for the last licensed antibody product in the last country. Either party may terminate the Mabwell Agreement prior to its expiration upon the other party’s uncured material breach, insolvency, or a challenge of the validity or enforceability of the patents licensed to such other party under the agreement. We may also terminate the Mabwell Agreement for convenience on 60 days’ written notice to Mabwell. In the event the Mabwell Agreement is terminated other than by us for cause, we have agreed to grant Mabwell an exclusive, sublicensable, worldwide license under our patent rights and know-how arising under the Mabwell Agreement to develop and commercialize products containing the licensed antibodies. In such circumstances, we and Mabwell will negotiate a royalty to be paid by Mabwell on the net sales of such products in the licensed territory.
Intellectual Property
Overview
We strive to protect the proprietary technology that we believe is important to our business, including seeking and maintaining patent protection in the United States and internationally for our current and future product candidates. We also rely on trademarks, copyrights, trade secrets, confidentiality procedures, employee disclosure, invention assignment agreements, know-how, continuing technological innovation and in-licensing opportunities to develop and maintain our proprietary position.
We seek to obtain domestic and international patent protection, and endeavor to promptly file patent applications for new commercially valuable inventions. We also rely on trade secrets to protect aspects of our business that are not amenable to, or that we do not consider appropriate for, patent protection.
We plan to continue to expand our intellectual property estate by filing patent applications directed to pharmaceutical compositions, methods of treatment, methods of manufacture or new inventions identified from our ongoing development of our product candidates, which include both small molecule and biologic products, such as antibodies. Our success will depend on our ability to obtain and maintain patent and other proprietary protection for commercially important technology, inventions and know-how related to our business, defend and enforce any patents that we may obtain, preserve the confidentiality of our trade secrets and operate without infringing the valid and enforceable patents and proprietary rights of third parties.
The patent positions of companies like ours are generally uncertain and involve complex legal, scientific and factual questions. In addition, the coverage claimed in a patent may be challenged in courts after issuance. Moreover, many jurisdictions permit third parties to challenge issued patents in administrative proceedings, which may result in further narrowing or even cancellation of patent claims. We cannot guarantee that our pending patent applications, or any patent applications that we may in the future file or license from third parties, will result in the issuance of patents. We cannot predict whether the patent applications we are currently pursuing will issue as patents in any particular jurisdiction or at all, whether the claims of any patent applications, should they issue, will cover our product candidates, or whether the claims of any issued patents will provide sufficient protection from competitors or otherwise provide any competitive advantage. We cannot predict the scope of claims that may be allowed or enforced in our patents. In addition, the coverage claimed in a patent application can be significantly reduced before the patent is issued, and its scope can be reinterpreted after issuance. Consequently, we may not obtain or maintain adequate patent protection for any of our product candidates.
Because patent applications in the United States and certain other jurisdictions are maintained in secrecy for 18 months or potentially even longer, and because publication of discoveries in the scientific or patent literature often lags behind actual discoveries and patent application filings, we cannot be certain of the priority of inventions covered by pending patent applications. Accordingly,
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we may not have been the first to invent the subject matter disclosed in some of our patent applications or the first to file patent applications covering such subject matter, and we may have to participate in interference proceedings or derivation proceedings declared by the United States Patent and Trademark Office, or USPTO, to determine priority of invention. For more information regarding the risks related to our intellectual property, see “Risk Factors-Risks Related to Our Intellectual Property.”
Patent Portfolio
Our patent portfolio includes patents and patent applications in the United States and selected jurisdictions outside of the United States. As of February 1, 2026, our patent portfolio in total consisted of 17 issued U.S. patents and 145 issued patents in foreign jurisdictions (e.g., Australia, China, United Kingdom, Germany, Mexico, Japan, and others), six PCT applications, 182 pending non-provisional applications (U.S., EP and other jurisdictions), and seven pending U.S. provisional applications, which include claims directed to compositions and methods of use.
The patent portfolio includes patents and applications with claims related to the following programs:
Heme Biosynthesis Modulation Portfolio - GlyT1 Inhibition - Bitopertin