At the 65th American Society of Hematology (ASH) Annual Meeting in San Diego, California, Ryan C Lynch, MD, Fred Hutch Cancer Center, Seattle, Washington, presented data on the high complete response rates of fixed-duration mosunetuzumab monotherapy in previously untreated patients with follicular lymphoma (FL) and marginal zone lymphoma (MZL) who had only low-grade cytokine release syndrome (CRS) and no immune effector cell-associated neurotoxicity syndrome (ICANS) of any grade.

Transcript:

My name is Ryan Lynch from the Fred Hutch Cancer Center in the University of Washington. At this meeting, I'm going to have the opportunity to present our early data on complete remission seen for patients treated with mosunetuzumab for untreated follicular and marginal zone lymphomas. 

This is a single-center investigator-initiated clinical trial in which we gave all patients 8 cycles of mosunetuzumab, followed by a [positron emission tomography] (PET) scan. Those achieving a complete remission then came off study therapy. [For] those who still had residual disease as measured by PET, we had the option to proceed with obinutuzumab and polatuzumab-vedotin for 6 additional cycles. 

The plan is to accrue 42 total patients, and so far, we've accrued 31 patients in the study. Efficacy data is available for the first couple dozen patients. Among these patients, complete remissions were seen in over 80% of patients. Among those who had to proceed with part B, all subsequently achieved a complete response. 

In terms of safety, the safety data so far with the study appears consistent with prior published data with mosunetuzumab. Approximately 2/3 of patients had grade 1 cytokine release syndrome, but no patients experienced grade 2 or higher cytokine release syndrome or required tocilizumab. Headache was common, experienced in 20 to 30% of patients, including at least 1 grade 2 headache. Rash was common [as well as] injection site reactions. As [such], the subcutaneous formulation of the mosunetuzumab [was] near universal with approximately 95% of patients experiencing at least 1 injection site reaction. 

Thank you so much for joining me at our presentation at ASH.
 

Source: 

Lynch RC, Poh C, Shadman M, et al. Early Complete Responses with Mosunetuzumab Monotherapy in Treatment-Naïve Follicular and Marginal Zone Lymphomas with Only Low-Grade Cytokine Release Syndrome. Presented at the ASH 65th Annual Meeting & Exposition; December 9-12 2023; San Diego, California. Abstract 4397