Matching-adjusted indirect comparison from the Lymphoma Epidemiology of Outcomes Consortium for Real World Evidence (LEO CReWE) study to a clinical trial of mosunetuzumab in relapsed or refractory follicular lymphoma.

Mosunetuzumab is a novel bispecific antibody targeting epitopes on CD3 on T cells and CD20 on B cells with the goal of inducing T-cell mediated elimination of malignant B cells. A recent pivotal phase I/II clinical trial (GO29781) demonstrated that mosunetuzumab induced an overall response rate (ORR) of 80%, complete response (CR) rate of 60%, and a median progression-free survival (PFS) of 17.9 months in patients with relapsed/refractory (R/R) follicular lymphoma (FL) following at least two prior lines of systemic therapy, including alkylator and anti-CD20 antibody-based therapy. Historical data from cohorts receiving therapy for R/R FL can provide some context for interpretation of single-arm trials. We compared the results from the mosunetuzumab trial to outcomes from a cohort of patients with R/R FL from the LEO Consortium for Real World Evidence (LEO CReWE). We applied clinical trial eligibility criteria to the LEO CReWE cohort and utilized matching- adjusted indirect comparison weighting to balance the clinical characteristics of the LEO CReWE cohort with those from the mosunetuzumab trial. ORR (73%, 95% CI: 65-80%) and CR rates (53%, 95% CI: 45-61%) observed in the weighted LEO CReWE cohort were lower than those reported on the mosunetuzumab trial (ORR=80%, 95% CI: 70-88%; CR=60%, 95% CI: 49-70%, respectively). PFS at 12 months was similar in the weighted LEO CReWE (60%, 95% CI: 51-69%) and the mosunetuzumab (58%, 95% CI: 47-68%) trial. Sensitivity analyses examining the impact of matching variables, selection of line of therapy, and application of eligibility criteria provide context for best practices in this setting.