FDA Approves Bispecific Antibody Mosunetuzumab-axgb to Treat Relapsed/Refractory Follicular Lymphoma

The FDA approved mosunetuzumab-axgb (Lunsumio; Genentech) for the treatment of adult patients with relapsed or refractory (R/R) follicular lymphoma (FL) following treatment with at least 2 prior lines of systemic therapy. Although a phase 3 trial has not yet been completed, the phase 2 trial GO29781 (NCT02500407) demonstrated high and durable response rates, allowing mosunetuzumab-axgb to be approved for this indication under accelerated approval. However, this indication’s continued approval may remain contingent on the verification of clinical benefit in a confirmatory trial.

The approval of mosunetuzumab-axgb, a CD20xCD3 T-cell engaging bispecific antibody, in the R/R FL indication is significant, as relapse for patients with FL remains quite common. Mosunetuzumab-axgb is now the first of its class approved by the FDA to treat FL, which is the most common slow-growing form of non-Hodgkin’s lymphoma.

“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 a press release. “[Mosunetuzumab-axgb] represents our first approved T-cell engaging bispecific antibody and builds on our legacy of more than 20 years of innovation in blood cancer.”

A CD20xCD3 T-cell engaging bispecific antibody is a new class of fixed-duration cancer immunotherapy, which is both off-the-shelf and readily available, making it possible to diminish wait times for initiating treatment in this patient population. Mosunetuzumab-axgb is currently set to be available in the United States in the coming weeks.

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

During the phase 2 GO29781 study, patients with heavily pretreated FL, including those who were at high risk of disease progression or whose disease was refractory to prior therapies, were enrolled in the trial. The results showed an objective response rate of 80% (72/90 [95% confidence interval (CI): 70-88]) in patients treated with mosunetuzumab-axgb, with a majority of patients maintaining responses for at least 18 months (57% [95% CI: 44-70]). Further, the median duration of response among patients who responded to mosunetuzumab-axgb was nearly 2 years (22.8 months [95% CI: 10-not reached]), with complete response achieved in 60% of patients (54/90 [95% CI: 49-70]).

In total, 218 patients with hematologic malignancies were treated with mosunetuzumab-axgb at the recommended dose, with the most common adverse events (AE) observed being cytokine release syndrome (CRS, 39%), which occurred at a median duration of 3 days (range: 1-29). Other common AEs (≥20%) observed were fatigue, rash, pyrexia, and headache.

Administered as an intravenous infusion for a fixed-duration, mosunetuzumab-axgb can be infused in an outpatient setting. However, hospitalization may be needed upon the occurrence of select AEs, as well as during subsequent infusions following a grade 2 CRS event. Additionally, hospitalization is recommended during subsequent infusions following a grade 3 CRS event.

“This additional treatment option is good news for people whose blood cancer has not responded to multiple lines of treatment because it can become more difficult to treat each time it returns,” Lee Greenberger, PhD, chief scientific officer of the Leukemia & Lymphoma Society, said in the press release. “This bispecific antibody is an off-the-shelf, accessible treatment option that has the potential to help those with relapsed or refractory follicular lymphoma achieve remission.”

Currently mosunetuzumab-axgb is also being investigated in a subcutaneous formulation. Additionally, the therapy is being assessed in phase 3 studies that will further investigate its impact in earlier lines of treatment in patients with non-Hodgkin’s lymphoma.

Reference

FDA Approves Genentech’s Lunsumio, a First-in-Class Bispecific Antibody, to Treat People With Relapsed or Refractory Follicular Lymphoma. San Francisco, CA: Genentech; December 22, 2022. Accessed December 23, 2022. https://www.businesswire.com/news/home/20221221005003/en