Preliminary Findings of a Phase Ib/II Trial Indicate Manageable Safety and Promising Efficacy for Mosunetuzumab in Combination with Lenalidomide (M+Len) in Previously Untreated (1L) Follicular Lymphoma (FL)

Background: First-line FL treatments typically include an anti-CD20 monoclonal antibody with alkylator-based chemotherapy. Despite encouraging efficacy, most patients (pts) eventually relapse; novel therapies that improve outcomes and prolong remission in 1L FL are needed. Also, chemotherapy-containing regimens may have substantial toxicities, emphasizing the need for new therapies with improved safety. Mosunetuzumab (M), a CD20xCD3 bispecific antibody that redirects T cells to eliminate malignant B cells, has shown manageable safety with high complete remission rates in pts with relapsed/refractory (R/R) FL after ≥2 prior lines of therapy (Budde et al. Lancet Oncol 2022). Lenalidomide (Len), a potent immunomodulatory agent, may have synergistic effects with M. Initial results from the CO41942 Phase Ib/II trial (NCT04246086) showed that M (intravenous) combined with Len had a manageable safety profile and encouraging chemotherapy-free anti-lymphoma activity in pts with R/R FL who had ≥1 prior line of therapy (Morschhauser et al. ASH 2021). We present preliminary safety, efficacy, and biomarker data from this ongoing trial of M (subcutaneous [SC]) combined with oral Len in pts with 1L FL who require systemic therapy.