ASH 2022: Durable Responses Observed with Mosunetuzumab Monotherapy in Relapsed/Refractory Follicular Lymphoma

In research presented by Nancy Bartlett, MD, a past Scientific Advisory Board (SAB) member and LRF grantee, durable clinical responses were observed in patients with relapsed/refractory follicular lymphoma (FL) who received mosunetuzumab monotherapy, according to updated results from a phase II study.

Mosunetuzumab (Lunsumio) is a T-cell-engaging bispecific monoclonal antibody that works by directing anti-cancer T cells to malignant B cells. Results from a phase II study involving the use of mosunetuzumab monotherapy in 90 patients with relapsed/refractory FL who had received at least two prior treatments were previously published in August of 2022. Here, the researchers presented updated results.

After a median 27 months of follow-up, approximately 78% of patients in the study achieved an objective response, and 60% achieved a complete response. Among complete responders, 79.5% remained in remission for at least 24 months. The 24-month progression-free survival rate among all patients was 51.4%. The researchers also reported that more patients responded to mosunetuzumab than their last prior therapy, and that the duration of responses was also higher, though retrospective comparisons are difficult to interpret without standardization of assessments.

Cytokine release syndrome (CRS) events occurred in 44.4% of patients, most of which occurred during the first cycle of therapy and were mild in nature. All CRS events resolved. The investigators reported that no new CRS events, or other serious or severe/fatal adverse events, had occurred since results were originally published and concluded that there was no evidence of chronic toxicity observed with mosunetuzumab therapy.

This study also included contributions from LRF SAB members Laurie H. Sehn, MD, MPH of BC Cancer, Vancouver; and Loretta Nostoupil, MD of The University of Texas MD Anderson Cancer Center; Philadelphia Lymphoma Rounds Steering Committee Chair Stephen J. Schuster, MD of Abramson Cancer Center/the University of Pennsylvania; and LRF Mantle Cell Lymphoma Consortium (MCLC) member Elizabeth Budde, MD of City of Hope.