BCMA-targeted T-cell engager therapy induces sustained remission in immune thrombocytopenia

Immune thrombocytopenia (ITP) is an autoimmune disease mediated by platelet-reactive antibodies, leading to accelerated platelet clearance and an increased risk of bleeding. Despite multiple available therapeutic options, durable treatment-free remissions remain uncommon in patients with refractory disease. Here, we report 3 patients with multidrug refractory ITP treated with a bispecific B-cell maturation antigen (BCMA)–targeting T-cell engager, teclistamab, approved for the treatment of multiple myeloma. Fixed-duration teclistamab therapy–induced platelet response within 4, 9, and 23 days, which was sustained after treatment discontinuation. The entirety of ITP-directed therapies was tapered and discontinued, and the 3 patients remain in treatment-free remission for 8, 6, and 3 months, respectively. Responses were associated with rapid depletion of B cells and plasma cells. Toxicity was manageable and largely limited to low-grade cytokine release syndrome, transient neutropenia, and infections that were readily controlled. These observations highlight BCMA-directed bispecific antibodies as a potential therapeutic strategy in autoimmune hematologic diseases and provide a rationale for prospective clinical trials.