ISB 2001, a Novel Trispecific Antibody, Shows Robust Activity in Relapsed/Refractory Multiple Myeloma

In this first-in-human phase 1 study, 21 heavily pre-treated relapsed/refractory multiple myeloma (RRMM) patients across 7 dose levels (5–1200 μg/kg) received weekly subcutaneous injections of ISB 2001 with step-up dosing. The agent demonstrated dose-proportional pharmacokinetics (tentative half-life >10 days) and achieved an overall response rate of 89.5% (78% in patients with prior T-cell therapy), along with rapid reductions in soluble BCMA levels and circulating B-cell counts. Transient T-cell activation and manageable Grade 1–2 cytokine release syndrome were observed, without dose-limiting toxicities or severe neurotoxicity.

The data indicate that ISB 2001 offers potent, tumor-directed activity with a favorable safety profile, supporting further clinical development and its potential for less frequent dosing in RRMM patients.