Bispecific Immunotherapy for Relapsed/Refractory Lymphoma

Bispecific T-cell engaging monoclonal antibodies have emerged as important options for patients with relapsed or refractory (R/R) B-cell malignancies. Investigators now report extended follow-up from an industry-sponsored, multicenter, phase 1/2 trial of mosunetuzumab, a CD20 x CD3 bispecific antibody, in patients with R/R indolent and aggressive B-cell non-Hodgkin lymphoma (iNHL and aNHL).

Mosunetuzumab was administered intravenously in 21-day cycles using a stepped-up dosing schedule in cycle 1, with corticosteroid premedication to mitigate infusion reactions and cytokine release syndrome during the first 2 cycles (optional with subsequent cycles); a dose of 30 mg on day 1 was administered beginning with cycle 3. Patients achieving complete response (CR) could discontinue treatment.

A total of 196 patients were treated with the full-dose regimen. At a median follow-up of 3.5 years (range 2.7–6.3 years), the overall (partial and complete) response rates were 65.7% (44/67) in patients with iNHL and 36.4% (47/129) in those with aNHL. Among patients with iNHL who achieved CR, no relapses were observed after 26 months. Among all patients with iNHL, 36-month progression-free survival (PFS) was 29.7%. In patients with aNHL, the median duration of response was 7.8 months (28.8 months for those with CR) and 36-month PFS was 10.3%. Of 12 patients with CR (8 iNHL; 4 aNHL) who were retreated with mosunetuzumab after prior discontinuation of therapy, 10 responded, including 7 who had a second CR. No new safety signals were observed.