Mosunetuzumab Earns FDA Priority Review for Relapsed/Refractory Follicular Lymphoma


Based on results of a phase 1/2 trial of single-agent mosunetuzumab in B-cell malignancies, the agent was granted priority review by the FDA for the treatment of relapsed/refractory follicular lymphoma.

The FDA has granted priority review to a biologics license application for mosunetuzumab (Lunsumio) as treatment for patients with relapsed/refractory follicular lymphoma following at least 2 prior lines of therapy, according to the drug maker Roche.1

The application for use of the first-in-class CD20 × CD3 T-cell engaging bispecific antibody in this indication is supported by data from the phase 1/2 GO29781 study (NCT02500407), which is exploring use of mosunetuzumab as a single-agent and in combination with atezolizumab (Tecetriq) as treatment for patients with relapsed/refractory B-cell non-Hodgkin lymphomas or chronic lymphocytic leukemia.

Results in patients with follicular lymphoma treated with mosunetuzumab monotherapy (n = 90) in the phase 2 expansion portion of the study were presented during the 2021 American Society of Hematology Annual Meetingand showed that complete responses (CRs) were observed in 60% (95% CI, 49%-70%) of patients per independent review facility (IRF) assessment. By investigator assessment, the CR rate was also 60% (95% CI, 49%-70%), which compared favorably with historical controls (P <.0001). Objective response rates (ORRs) by IRF and investigator assessment were 80% (95% CI, 70%-88%) and 78% (95% CI, 68%-86%), respectively. Median duration of response was 22.8 months (95% CI, 9.7–not evaluable) and median progression-free survival was 17.9 months (range, 10.1–NE).2

Adverse effects (AEs) were experienced by all patients, with 92.2% determined to be related to the study drug. Of the 70% of patients who experienced grade 3/4 AEs, 51.1% were related to mosunetuzumab. Serious AEs of any cause were experienced by 46.7% of patients, with 33.3% being related to mosunetuzumab. Moreover, there were only 2 patient deaths and neither was associated with the exploratory agent.

Cytokine release syndrome did occur in 44.4% of patients but was predominantly grade 1 (25.6%) or grade 2 (16.7%) in severity. Only 1 event each of grade 3 and grade 4 CRS were reported, both of which eventually resolved.

“New therapeutic options are needed for follicular lymphoma, which often relapses after initial therapy and becomes increasingly difficult to treat each time it returns. Clinical trial results have demonstrated durable responses with Lunsumio in advanced follicular lymphoma, representing a step toward shifting the treatment paradigm,” Levi Garraway, MD, PhD, chief medical officer and head of Global Product Development at Roche, said in a statement. “Since Lunsumio does not require the collection or genetic modification of patient cells, it could become an effective, fixed-duration outpatient option without the barriers of travelling to a major academic centre.”

Results from the trial were later published in the Journal of Clinical Oncology and revealed that in patients with follicular lymphoma who were treated with mosunetuzumab monotherapy, consistent CR rates were noted in patients with disease that was refractory to both a prior anti-CD20 antibody and alkylating agent (55.9%), and in those with progressive disease within 24 months of starting first-line therapy (54.5%).3

Mosunetuzumab had been granted breakthrough therapy designation in 2020 and orphan drug designation in 2018 for this indication. Additionally, the European Commission granted conditional marketing authorisation to the agent in June 2022 for relapsed/refractory follicular lymphoma after 2 or more prior systemic therapies.

A decision regarding approval of this indication is expected on or before December 29, 2022.


  1. FDA grants priority review to Roche’s Lunsumio for people with relapsed or refractory follicular lymphoma. News release. Roche. July 6, 2022. Accessed July 6, 2022.
  2. Budde EL, Sehn LH, Matasar M, et al. Mosunetuzumab monotherapy is an effective and well-tolerated treatment option for patients with relapsed/refractory (R/R) follicular lymphoma (FL) who have received ≥2 prior lines of therapy: pivotal results from a phase I/II study. Blood. 2021;138(suppl 1):127. doi:10.1182/blood-2021-145872
  3. Budde LE, Assouline S, Sehn LH, et al. Single-agent mosunetuzumab shows durable complete responses in patients with relapsed or refractory B-cell lymphomas: phase I dose-escalation study. J Clin Oncol. 2022;40(5):481-491. doi:10.1200/JCO.21.00931
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