Ouro Medicines Receives U.S. FDA Orphan Drug Designation for Gamgertamig (OM336) for Immune Thrombocytopenia

Immune thrombocytopenia (ITP) is the second indication for which gamgertamig has received Orphan Drug Designation (ODD), following a first ODD for autoimmune hemolytic anemia (AIHA)

Dosing is complete in the first cohort of the Ouro Medicines global basket study evaluating gamgertamig in autoimmune cytopenias, including ITP and AIHA

SOUTH SAN FRANCISCO, Calif., Dec. 8, 2025 /PRNewswire/ -- Ouro Medicines, a biotechnology company developing immune reset therapeutics for people living with chronic, immune-mediated diseases, today announced that gamgertamig (OM336), the company's BCMAxCD3 T cell engager antibody candidate, has been granted U.S. Food and Drug Administration (FDA) Orphan Drug Designation (ODD) for development in the treatment of immune thrombocytopenia (ITP). ITP is an autoimmune disease driven by autoantibodies which cause destruction of platelets, leading to signs and symptoms that include bleeding and fatigue.

"The FDA's decision to grant Orphan Drug Designation to gamgertamig for development in the treatment of ITP means that gamgertamig has now received ODD for two indications in our ongoing Phase 1b autoimmune cytopenias basket study," said Jaideep Dudani, Ph.D., Chief Executive Officer of Ouro Medicines. "This second designation underscores the promise for gamgertamig to address unmet needs in ITP, offering an immune reset approach with differentiated properties as a clinical candidate. With dosing now complete for the first cohort in this study and enrollment actively ongoing in the second cohort, we continue to expect results from this study in 2026."

The U.S. FDA ODD program is intended to advance therapeutics developed to treat, prevent or diagnose diseases that affect fewer than 200,000 people in the U.S., and provides benefits including seven years of marketing exclusivity following a potential approval.

The gamgertamig (OM336) basket study in autoimmune cytopenias is an open-label, multi-site, Phase 1b study conducted in the U.S. and Australia evaluating safety, tolerability and pharmacokinetics of gamgertamig in adult participants with active autoimmune cytopenias, specifically relapsed/refractory ITP, AIHA, or both (NCT07083960). Exploratory endpoints include clinical efficacy measures and blood biomarkers. Gamgertamig is administered via subcutaneous injection in ascending dose cohorts, with the primary endpoint evaluated at Week 12.

About Gamgertamig (OM336)
Gamgertamig (OM336) is an investigational BCMAxCD3 bispecific antibody designed to induce T cell-dependent cellular cytotoxicity of cells expressing BCMA, which are thought to drive certain immune-mediated diseases through the production of autoantibodies. By depleting these cell populations, it may be possible to offer patients extended periods of relief and avoid the challenges of treatment with immunosuppressive therapies.

With a CD3-targeting arm engineered for the reduced induction of T cell cytokines, referred to as a 'detuned' CD3-targeting arm, gamgertamig is designed to avoid severe immune activation while retaining potency of target cell depletion. This detuned arm may contribute to an expanded therapeutic index. Gamgertamig has a long half-life, which enables subcutaneous dosing, and has additional properties that may contribute to safety and tolerability.

Gamgertamig has a record of clinical evaluation across investigator-initiated and company-sponsored studies in oncology and immune-mediated diseases, which has contributed to an understanding of its properties and potential applications. Gamgertamig has been granted U.S. Food and Drug Administration (FDA) Orphan Drug Designation (ODD) for development in the treatment of autoimmune hemolytic anemia (AIHA) and immune thrombocytopenia (ITP).

About Autoimmune Cytopenias
Autoimmune cytopenias are diseases resulting primarily from autoantibody-mediated destruction of blood cells. These include autoimmune hemolytic anemia (AIHA), which affects red blood cells, and immune thrombocytopenia (ITP), which affects platelets. Both indications are potentially life-threatening. In AIHA, autoantibodies lead to the premature destruction of the body's red blood cells (known as hemolysis). Individuals with AIHA may experience signs and symptoms including debilitating fatigue, thromboembolism, dizziness, palpitations and shortness of breath. ITP occurs when the body's immune system attacks platelets, the blood cells that help control bleeding. This can lead to low platelet counts and hemorrhagic (bleeding) episodes that can be life-threatening.

About Ouro Medicines
Ouro Medicines is a biotechnology company dedicated to developing immune reset therapeutics for people living with chronic immune-mediated diseases. Ouro's approach is focused on leveraging T cell engagers in B cell-mediated diseases to achieve immune resets that create durable remissions without ongoing immunosuppression. Based in San Francisco and launched in 2025, Ouro was founded by Monograph Capital in partnership with GSK. Ouro is also backed by leading investors TPG, NEA and Norwest. For more information visit www.ouromedicines.com or follow us on LinkedIn.

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SOURCE Ouro Medicines