Dr Mohty on Bispecific Antibodies in R/R Multiple Myeloma

Mohamad Mohty, MD, PhD, professor, hematology, head, the Hematology and Cellular Therapy Department, Saint-Antoine Hospital and Sorbonne University, discusses unmet needs in patients with relapsed/refractory multiple myeloma and the rationale for investigating elranatamab (PF-06863135) monotherapy in this population in the phase 2 MagnetisMM-3 trial (NCT04649359).

MagnetisMM-3 is an open-label, international trial evaluating the efficacy of elranatamab, a novel bispecific antibody, in patients with relapsed/refractory multiple myeloma. Elranatamab targets both BCMA-expressing myeloma cells and CD3-expressing T cells. As a class of drugs, bispecific antibodies use immune therapy to target cancers, such as malignant plasma cells in multiple myeloma, Mohty says.

Cohort A of MagnetisMM-3 enrolled 123 patients with relapsed/refractory disease who had received no prior BCMA-directed therapies. These patients had a median of 5 prior lines of therapy (range, 2-22), and all patients were triple-class refractory, meaning they had each received and progressed on at least 1 prior immunomodulatory drug, proteasome inhibitor, and anti-CD38 monoclonal antibody. This population has historically had limited treatment options, and bispecific antibodies represent new potential options, Mohty emphasizes.

In MagnetisMM-3, patients received 76 mg of subcutaneous elranatamab once weekly in 28-day cycles. Overall response rate (ORR) by blinded independent central review (BICR) served as the primary end point of this trial, with key secondary end points including duration of response, complete response (CR) rate, time to response, progression-free survival, minimal residual disease (MRD)–negativity rate, overall survival, and safety.

At a median follow-up of 14.7 months (range, 0.2-25.1), the confirmed ORR by BICR was 61.0% (95% CI, 51.8%-69.6%), including a CR/stringent CR (sCR) rate of 35.0% and a very good partial response rate of 56.1%. Among evaluable patients who achieved a CR/sCR, 89.7% achieved MRD negativity at the sensitivity threshold of 10–5. Of the patients who responded, the median time to response was 1.2 months (range, 0.9-7.4).