Ouro Medicines Announces Expansion of Clinical Development for OM336 in Sjögren's Disease and Idiopathic Inflammatory Myopathy

Multinational basket study extends "immune reset" approach into additional B and plasma cell-mediated indications

 First Phase 1b study data expected in 2026

SOUTH SAN FRANCISCO, Calif., Oct. 15, 2025 /PRNewswire/ -- Ouro Medicines, a biotechnology company developing immune reset therapeutics for people living with chronic, immune-mediated diseases, today announced the initiation of a multinational Phase 1b study of OM336, a BCMAxCD3 T cell engager antibody candidate, in Sjögren's disease and idiopathic inflammatory myopathy (IIM). Both indications are B and plasma cell-mediated autoimmune diseases with a high burden for patients and limited treatment options.

"This study reflects Ouro's strategy of expanding OM336 development to additional immune-mediated diseases where an 'immune reset' approach would be transformative," said Neely Mozaffarian, M.D., Ph.D., Chief Medical Officer of Ouro Medicines. "Through transient depletion of memory B cells and plasma cells, OM336 has the potential to deliver long-lasting remission to patients living with these challenging conditions." 

"This additional study, expanding beyond autoimmune cytopenias, is our second study to begin in less than a year following corporate launch and underscores Ouro's commitment to redefine the standard of care for patients with immune-mediated diseases," commented Jaideep Dudani, Ph.D., Chief Executive Officer of Ouro Medicines. "As we expand to additional indications, also with high need and compelling opportunity for OM336, we continue to be focused on our goal of bringing this candidate into investigation for a wide range of indications as a potentially new class of therapy. We expect initial interim results from this Phase 1b study in Sjögren's and idiopathic inflammatory myopathy in 2026."

This open-label, multi-site, Phase 1b dose escalation study with a basket design will evaluate the safety, tolerability and pharmacokinetics of OM336 in adult participants with autoantibody-positive, relapsed/refractory Sjögren's disease or IIM (including dermatomyositis, polymyositis, immune-mediated necrotizing myopathy and anti-synthetase syndrome). OM336 will be administered in the first three weeks by subcutaneous injection in cohorts at ascending dose levels, with follow-up through Week 52. Exploratory endpoints include measures of clinical efficacy, patient-reported outcomes and biomarkers relevant to each indication.

Ouro previously announced the initiation of clinical development with OM336 in autoimmune cytopenias (AIC), including autoimmune hemolytic anemia (AIHA) and immune thrombocytopenia (ITP). The AIC trial, which is actively enrolling and dosing patients, is supported by results from investigator-initiated studies that demonstrated promising responses in patients with severe, relapsed/refractory AIC. The company expects initial results in the Ouro-sponsored AIC trial in 2026.

About OM336
OM336 is an investigational BCMAxCD3 bispecific antibody designed to induce T cell-dependent cellular cytotoxicity of target cells expressing BCMA. With a CD3-targeting arm engineered for the reduced induction of T cell cytokines, referred to as a 'detuned' CD3-targeting arm, OM336 is designed to avoid severe immune activation while retaining potency of target cell depletion, which may expand its therapeutic index. OM336 has a long half-life, which enables subcutaneous dosing, and additional properties that may contribute to safety and tolerability.

More than 100 patients have been dosed with OM336 across investigator-initiated and company-sponsored clinical studies in oncology indications including multiple myeloma, and in immune-mediated indications including autoimmune hemolytic anemia (AIHA), immune thrombocytopenia (ITP) and autoimmune bullous diseases. OM336 has been granted U.S. Food and Drug Administration (FDA) Orphan Drug Designation (ODD) for development in the treatment of AIHA.

About Sjögren's Disease
Sjögren's disease is a common, chronic, systemic autoimmune disease that occurs when the immune system attacks the body's own exocrine glands, leading to the hallmark symptoms of severe dry eyes and dry mouth. Beyond glandular dysfunction, many patients develop serious organ manifestations involving the musculoskeletal, pulmonary, cardiovascular, renal and gastrointestinal systems. Current treatment options are largely limited to symptomatic management and broad immunosuppressive therapies may carry significant side effects and provide inadequate disease control for many patients.

About Idiopathic Inflammatory Myopathy
Idiopathic inflammatory myopathy (IIM) encompasses a group of rare, chronic autoimmune diseases, which occur when the immune system attacks healthy muscle tissue, resulting in chronic inflammation, progressive muscle weakness and significant functional impairment. The disease frequently involves organ systems beyond muscle, including the lungs, heart, skin and joints, with many patients developing life-threatening complications such as interstitial lung disease. Autoantibody-driven manifestations can significantly impact quality of life and long-term outcomes. Current treatment approaches rely primarily on broad immunosuppressive therapies, including corticosteroids and conventional disease-modifying drugs, which often provide incomplete disease control and may be associated with substantial toxicities.

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