CAMBRIDGE, Massachusetts, United States — October 27, 2026
Cullinan Therapeutics, Inc., a clinical-stage biopharmaceutical company developing potential first- or best-in-class, disease-modifying T cell engagers for autoimmune diseases and cancer, announced that the U.S. Food and Drug Administration (FDA) and Australia’s Therapeutic Goods Administration have cleared the initiation of a global Phase 1b/2a clinical trial of velinotamig in adults with relapsing and refractory immune thrombocytopenia (ITP) and warm autoimmune hemolytic anemia (wAIHA). The open-label, multicenter study will assess the safety, tolerability, pharmacokinetics, pharmacodynamics, immunogenicity and preliminary clinical activity of velinotamig, a subcutaneous BCMAxCD3 T cell engager designed to target antibody-producing plasma cells. The clinical program addresses two serious autoimmune blood disorders in which disease-causing autoantibodies contribute to the destruction of platelets or red blood cells. Despite available treatments, some patients experience recurring disease, ongoing treatment dependence or significant adverse effects. Cullinan is evaluating whether a defined, short-duration treatment regimen could provide meaningful and potentially durable disease control in these patient populations.
Phase 1b/2a Trial to Evaluate Velinotamig in Autoimmune Cytopenias
The global Phase 1b/2a study, registered as NCT07738822, will enroll adults with relapsing and refractory ITP or wAIHA and evaluate a defined course of four subcutaneous doses of velinotamig. The trial consists of two parts: Part A, a Phase 1b multiple-ascending-dose phase intended to assess dose-related safety and tolerability, and Part B, a Phase 2a dose-expansion phase that will evaluate selected dose regimens in separate ITP and wAIHA groups. The primary objectives include evaluating safety, tolerability and effects on disease activity, while additional assessments will characterize how the medicine behaves in the body and its biological effects. Velinotamig is designed to redirect cytotoxic T cells toward BCMA-expressing cells, including plasma cells responsible for producing pathogenic autoantibodies. The trial will generate early clinical evidence on whether targeting these cells can reduce autoimmune activity in patients whose conditions have persisted or returned despite previous treatment. As an investigational therapy, velinotamig’s safety and effectiveness in autoimmune cytopenias remain to be established through clinical evaluation.
BCMA-Directed Plasma Cell Depletion Targets Disease-Causing Autoantibodies
Velinotamig, also known as CLN-803 or GR1803, is a bispecific BCMAxCD3 T cell engager engineered with high-affinity binding to B-cell maturation antigen (BCMA) and lower-affinity binding to CD3 on T cells. The approach is intended to direct T cells toward BCMA-expressing plasma cells while limiting nonspecific T cell activation and associated cytokine-related toxicity. By targeting antibody-producing plasma cells, the therapy is being developed for autoimmune diseases in which pathogenic autoantibodies play a central role. Cullinan’s clinical strategy includes complementary T cell engagers directed at CD19 and BCMA, which target different immune cell populations implicated in autoimmune conditions. The company has highlighted emerging clinical evidence from BCMA-directed therapies as support for further investigating plasma cell depletion in autoimmune cytopenias, including difficult-to-treat disease. However, the potential for velinotamig to produce sustained clinical benefit, and its overall safety profile, will require confirmation in ongoing and future studies. The current trial expands the investigation of BCMA-directed treatment into two blood disorders characterized by recurrent immune-mediated destruction of blood cells.
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Global Development Expands Cullinan’s Autoimmune Pipeline
Cullinan holds an exclusive global license to velinotamig for all indications outside Greater China from Genrix Bio, which is evaluating the medicine in a Phase 1b/2a study in patients with refractory systemic lupus erythematosus (SLE) in China. Additional autoimmune indications are also under consideration. Cullinan stated that clinical data evaluating velinotamig in autoimmune diseases are scheduled to be presented by Genrix Bio at the American College of Rheumatology Convergence 2026 meeting on November 8, 2026. Updated results from the ongoing study in refractory SLE are expected to provide further information about BCMA-directed plasma cell depletion across autoimmune conditions. ITP is an autoimmune disorder involving increased platelet destruction and impaired platelet production, which can cause bruising, bleeding and fatigue. Warm autoimmune hemolytic anemia occurs when autoantibodies promote premature red blood cell destruction, potentially leading to anemia, shortness of breath and jaundice. Both conditions can be serious, and sustained disease control remains challenging for some patients. Through the new global trial, Cullinan aims to evaluate an investigational treatment approach for people with relapsing or refractory disease while building its broader pipeline of T cell engager therapies for immunology and oncology.
Source:Cullinan Therapeutics, Press release
