Gamgertamig Nets FDA Fast Track Designation in Autoimmune Hemolytic Anemia and Immune Thrombocytopenia

The FDA has granted fast track designation to gamgertamig (OM336) for the treatment of patients with autoimmune hemolytic anemia and immune thrombocytopenia.¹

Gamgertamig is being investigated in an open-label, multinational, phase 1b basket study(NCT07083960), which is enrolling patients with active autoimmune cytopenias, including relapsed/refractory autoimmune hemolytic anemia and immune thrombocytopenia, in the US and Australia.^1,2 The primary end points of the trial are safety and tolerability.² Key secondary end points include pharmacokinetics and immunogenicity. Efficacy, patient-reported outcomes, and biomarkers and glucocorticoid-sparing effects are being evaluated as key exploratory end points.

“Fast Track designation for gamgertamig in both autoimmune hemolytic anemia and immune thrombocytopenia underscores the need for new treatment options in these potentially life-threatening conditions,” Neely Mozaffarian, MD, PhD, chief medical officer of Ouro Medicines, stated in a news release.¹ “Our ongoing clinical trial of gamgertamig in autoimmune cytopenias, including autoimmune hemolytic anemia and immune thrombocytopenia, combined with our study in Sjögren’s disease and idiopathic inflammatory myopathies, will continue to generate meaningful data in these indications, offering the potential of an immune reset approach, which could redefine the standard of care for these immune-mediated conditions. We are highly encouraged by the data generated to date in Ouro-sponsored and investigator-initiated studies of gamgertamig in several indications.”

What is the clinical rationale for the phase 1b study of gamgertamig in autoimmune cytopenias?

Gamgertamig is an investigational BCMA- and CD3-targeted bispecific antibody that is designed to induce T-cell–dependent cellular cytotoxicity of cells expressing BCMA.Through the depletion of these cell populations, the agent could avoid several challenges associated with immunosuppressive therapies.

The CD3-targeting arm of gamgertamig is engineered for the reduced induction of T-cell cytokines. The agent is designed to avoid severe immune activation and to retain the potency of target cell depletion.

Data from initial clinical studies demonstrated that gamgertamig showed efficacy in patients with relapsed/refractory autoimmune hemolytic anemia.² A durable benefit was reported following the discontinuation of background therapies. Gamgertamig mediated deep tissue depletion of both plasma and CD19-positive B cells, suggesting that the potential for an “immune reset” and a basis for sustained remission off-therapy.

What are the key design characteristics of the phase 1b study of gamgertamig in autoimmune hemolytic anemia and immune thrombocytopenia?

The study is enrolling patients who are 18 to 75 years of age with active, relapsed/refractory autoimmune cytopenias with or without concurrent autoimmune diseases. Up to 32 patients will be enrolled across approximately 12 sites in the US and Australia.

Each dose of gamgertamig will be administered as fractionated subcutaneous injections over the first 2 to 3 weeks of the study, then discontinued. Patients who achieve a clinical response may taper or discontinue their background therapies for autoimmune cytopenias per investigator judgement.

Patients will be enrolled to dose regimens 1 (n = 3), 2 (n = 3), 3 (n = 3), or 4 (n = 3). Patients will then proceed to dose expansion cohorts 1 through 4, each of which will enroll 0 to 5 patients. Follow-up will occur through week 52. Dosing has been completed in the first cohort, and enrollment is actively ongoing in subsequent cohorts.¹

Gamgertamig is also being investigated in an open-label, multinational, phase 1 basket study (NCT07229144), which is enrolling adult patients with active, autoantibody-positive, relapsed/refractory Sjögren's disease or idiopathic inflammatory myopathy, including dermatomyositis, polymyositis, immune-mediated necrotizing myopathy, and anti-synthetase syndrome.

References

1. Ouro Medicines receives U.S. FDA fast track designation for gamgertamig in immune thrombocytopenia and autoimmune hemolytic anemia. News release. Ouro Medicines. January 20, 2026. Accessed January 20, 2026. https://www.ouromedicines.com/news/012026/
2. Broome C, Hsu D, Choi P, Zhou C, Mozaffarian N. Trial in progress: a phase 1b, open-label, multiple ascending dose study of OM336, a novel BCMAxCD3 T cell engager, in patients with relapsed/refractory autoimmune cytopenias (NCT07083960). Blood. 2025;146(suppl 1):2900. doi:10.1182/blood-2025-2900