The results come from the phase 1/2 CAMMA 2 trial (NCT05535244). Cohort A1 of the trial included 21 patients with relapsed or refractory, triple-class refractory multiple myeloma who had received treatment with a BCMA-targeted ADC (n=10) or CAR T-cell therapy (n=11). Prior treatment with a BCMA-targeted bispecific antibody was not allowed.

The patients’ median age at baseline was 64 (range, 36-80) years, 52% were men, 56% had high-risk cytogenetics, and 33% had extramedullary disease. They had received a median of 6 prior lines of therapy (range, 4-15), 57% were penta-refractory, and 57% were refractory to their last line of therapy.

On study, the patients received infusions of cevostamab, an FcRH5-CD3 bispecific antibody, every 3 weeks until disease progression or unacceptable toxicity. In cycle 1, they received step-up dosing to 160 mg by day 8. From cycle 2 onward, they received 160 mg on day 1.

The objective response rate was 67% in the entire cohort, 73% among patients who had prior CAR T-cell therapy, and 60% among those who had prior ADC treatment. Rates of very good partial response or better were 38%, 55%, and 20%, respectively. Rates of stringent complete response were 14%, 18%, and 10%, respectively.

At a median follow-up of 11 months, 6 of the 14 responders remained in response. FcRH5 expression was not associated with response.