On December 22, the U.S. Food and Drug Administration (FDA) approved mosunetuzumab-axgb (Lunsumio) for the treatment of adults with relapsed or refractory follicular lymphoma after two or more lines of systemic therapy. Mosunetuzumab-axgb is a CD20/CD3 T-cell–engaging bispecific antibody and represents a new class of fixed-duration cancer immunotherapy, which is off-the-shelf and will be available in the United States in the coming weeks. Continued approval for this indication may be contingent upon verification and description of clinical benefit in a confirmatory trial.
The drug was granted accelerated approval based on response rate reported in the phase II GO29781 study (ClinicalTrials.gov identifier NCT02500407). GO29781 is a multicenter, open-label, dose-escalation and dose-expansion trial evaluating the safety, efficacy, and pharmacokinetics of mosunetuzumab-axgb in people with relapsed or refractory B-cell non-Hodgkin’s lymphoma. Outcome measures include complete response rate (best response) by independent review facility (primary endpoint), objective response rate, duration of response, progression-free survival, safety, and tolerability (secondary endpoints).
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Results from the study showed high and durable response rates. An objective response was seen in 80% of patients treated with mosunetuzumab-axgb, and a majority of these patients (57%) maintained responses for at least 18 months The median duration of response among those who responded was 22.8 months. A complete response was achieved in 60% of patients.
Among 218 patients with hematologic malignancies who received mosunetuzumab-axgb at the recommended dose, the most common adverse event was cytokine-release syndrome, the median duration of which was 3 days. Other common adverse events (≥ 20%) included fatigue, rash, pyrexia, and headache.
Mosunetuzumab-axgb is administered as an intravenous infusion for a fixed duration, which allows for time off therapy, and can be infused in an outpatient setting. Hospitalization may be needed to manage select adverse events.The content in this post has not been reviewed by the American Society of Clinical Oncology, Inc. (ASCO®) and does not necessarily reflect the ideas and opinions of ASCO®.