Single-Agent Mosunetuzumab Shows Durable Complete Responses in Patients With Relapsed or Refractory B-Cell Lymphomas:...

Area of Science:

• Oncology
• Immunotherapy
• Hematology

Background:

• Mosunetuzumab is an investigational bispecific antibody designed to target CD20 and CD3.
• It redirects T cells to engage and eliminate malignant B cells, offering a potential new treatment for B-cell lymphomas.

Purpose of the Study:

• To evaluate the safety, tolerability, and efficacy of mosunetuzumab in patients with relapsed or refractory (R/R) B-cell non-Hodgkin lymphomas (B-NHL).
• To establish the recommended Phase II dose for mosunetuzumab in this patient population.

Main Methods:

• A first-in-human trial (NCT02500407) involving 230 patients with R/R B-NHL.
• Mosunetuzumab was administered intravenously in 3-week cycles, with dose escalation in Group B (n=197) using step-up dosing.
• Doses up to 2.8 mg (Group A) and 60 mg (Group B) were assessed.

Main Results:

• The maximum tolerated dose was not exceeded. Common adverse events in Group B included neutropenia (28.4%) and cytokine release syndrome (27.4%), mostly low-grade.
• Overall response rates were 34.9% for aggressive and 66.2% for indolent R/R B-NHL.
• Complete response rates were 19.4% and 48.5% for aggressive and indolent R/R B-NHL, respectively, with durable responses observed.

Conclusions:

• Mosunetuzumab, particularly with step-up dosing, demonstrates a manageable safety profile in R/R B-NHL.
• The treatment induces durable complete responses, supporting its further investigation.
• The expansion stage is ongoing at a selected dose level for further study.