CD20-CD3 Bispecific Antibody Shows High Efficacy in Relapsed/Refractory Follicular Lymphoma

Mosunetuzumab showed high potency in patients with relapsed/refractory (R/R) follicular lymphoma (FL), according to data from a large expansion cohort from an ongoing phase 1/2 trial of patients who were treated at the recommended phase 2 dose.

More than 3 out of 4 patients treated with the CD20-CD3 bispecific antibody experienced an objective response (ORR) of 78.9% and more than half had a complete response (CR) of 57.8%. The responses were maintained for at least a year in most patients.

The single-arm, pivotal expansion cohort consisted of 90 patients, with FL (grade 1–3a, ECOG performance status ≤1), and were R/R to ≥2 prior lines of therapy including an anti CD20 antibody and an alkylator. At entry, 76.7% of subjects had stage III or IV disease.

The median number of prior lines of therapy was 3 (range, 2–10). In addition to CD20 antibodies and alkylators, prior cancer therapies included anthracyclines (82.2%), autologous stem cell transplant (21.1%), and CAR-Ts (3.3%), among others. Additionally, 68.9% of pts were refractory to their last therapy, 78.9% to any prior anti-CD20 antibody, and 53.3% to any prior anti-CD20 antibody and an alkylator (double refractory).

Patients who achieved a CR discontinued therapy; those with a partial response (PR) or stable disease continued treatment for a total of 17 cycles unless disease progression or unacceptable toxicity occurred.

Step-up dosing mitigated cytokine-release syndrome (CRS), enabling treatment without mandatory hospitalization, wrote lead author Elizabeth Budde, MD, PhD, City of Hope, Duarte, CA, and co-authors.

As of March 15, 2021, median time on study was 12.9 months (range, 2.0–22.1). The ORR and CR rates were 78.9% (71/90 pts) and 57.8% (52/90), respectively. Median PFS was 17.9 months (95% CI: 12.0–not estimable).

Source:

Budde LE, Sehn LH, Matasar MJ, et al. Mosunetuzumab Monotherapy Is an Effective and Well-Tolerated Treatment Option for Patients with Relapsed/Refractory (R/R) Follicular Lymphoma (FL) Who Have Received ≥2 Prior Lines of Therapy: Pivotal Results from a Phase I/II Study. Blood. 2021;138:127. doi:10.1182/blood-2021-145872