FDA Approves Mosunetuzumab-axgb for Relapsed/Refractory Follicular Lymphoma

In the pivotal phase 2 GO29781 study, the objective response rate and response durability was high, leading to the FDA approval of mosunetuzumab for the treatment of relapsed or refractory follicular lymphoma.

The FDA has granted approval to mosunetuzumab-axgb (Lunsumio) for the treatment of adult patients with relapsed or refractory (R/R) follicular lymphoma (FL) after 2 or more lines of systemic therapy.1

Approval was granted based on the positive objective response rate observed with the agent in pivotal phase 2 GO29781 study (NCT02500407). Eighty percent of pretreated patients who received mosunetuzumab in the study had durable response rates. The complete remission rate in the study was 60%. Based on this approval, CD20xCD3 T-cell engaging bispecific antibody approved by the FDA to treat FL.1,2

“This approval is a significant milestone for people with relapsed or refractory follicular lymphoma, who have had limited treatment options until now,” said Elizabeth Budde, MD, PhD, hematologic oncologist and associate professor, City of Hope Division of Lymphoma, Department of Hematology & Hematopoietic Cell Transplantation, and Lunsumio clinical trial investigator, in a press release. “As a first-in-class T-cell engaging bispecific antibody that can be initiated in an outpatient setting, Lunsumio’s high response rates and fixed-duration could change the way advanced follicular lymphoma is treated.”

GO29781 is a single-arm, multicenter, phase 2 study, investigators enrolled 90 patients with follicular lymphoma grade 1-3a, ECOG performance status of 0 to 1, and receipt of at least 2 prior lines of therapy, including an anti-CD20 antibody and an alkylator agent.2

At baseline, the median age of patients was 60 years. Eighty-one percent of patients remain in follow-up, and 62% completed all therapy. Patients received a median of 3 prior lines of therapy (range, 2-10), 69% were refractory to their last prior therapy, 79% were refractory to any prior anti-CD20 therapy, and 53% were double refractory to prior anti-CD20 and alkylator therapy.

Results from the study also showed that the median progression-free survival (PFS) was 24 months (95% CI, 12–not reached [NR]) and the overall survival (OS) was NR (NR-NR). At 2 years, the PFS and OS rates were 48% (95% CI, 36%-60%) and 87% (95% CI, 80%-94%), respectively.

In terms of safety, there were no new cases of cytokine release system (CRS) with extended follow-up. Most cases of CRS were low grade. The safety profile overall supported the use of mosunetuzumab as an outpatient regimen.

There were also no new treatment-related adverse events (TRAEs) reported since the initial publication of data. Grade 3 or higher treatment-related AEs were observed in 51% of patients. the most common grade 3 or higher TRAEs were neutropenia and hypophosphatemia. Two deaths occurred during the study.

“Despite treatment advances, follicular lymphoma remains incurable and relapse is common, with outcomes worsening following each consecutive treatment,” said Levi Garraway, MD, PhD, chief medical officer and head of Global Product Development., in the press release. “Lunsumio represents our first approved T-cell engaging bispecific antibody and builds on our legacy of more than 20 years of innovation in blood cancer.”


1. FDA approves Genentech’s Lunsumio, a first-in-class bispecific antibody, to treat people with relapsed or refractory follicular lymphoma. News release. December 23, 2022. Accessed December 23, 2022. https://bit.ly/3WJw6B3

2. Bartlett NL, Sehn LH, Matasar MJ, et al. Mosunetuzumab monotherapy demonstrates durable efficacy with a manageable safety profile in patients with relapsed/refractory follicular lymphoma who received ≥2 prior therapies: updated results from a pivotal phase II study. Presented at: 2022 ASH Annual Meeting; December 10-13, 2022; New Orleans, LA. Abstract 610.