FDA Approves Subcutaneous Mosunetuzumab for R/R Follicular Lymphoma

The FDA has approved mosunetuzumab (Lunsumio VELO) as a subcutaneous formulation for the treatment of adult patients with relapsed or refractory follicular lymphoma following 2 or more prior lines of systemic therapy.¹

The approval was supported by data from the phase 1/2 GO29781 study (NCT02500407). In the study, among patients treated with the fixed-duration subcutaneous formulation, the overall response rate (ORR) was 75% (95% CI, 64%-83%), including a complete response (CR) rate of 59% (95% CI, 48%-69%). The median duration of response (DOR) was 22.4 months (95% CI, 16.8-22.8).

“This approval is a significant step in broadening access to effective treatments for people living with follicular lymphoma,” Ian Flinn, MD, PhD, of Tennessee Oncology and One Oncology in Nashville, stated in a news release. “With its manageable cytokine release syndrome [CRS] profile and reduced administration time, [subcutaneous mosunetuzumab] enables oncologists to deliver advanced care in community practice settings.”

Notably, on November 18, 2025, the European Commission granted conditional marketing authorization to subcutaneous mosunetuzumab for the same indication.²

What was the design of the GO29781 study?

GO29781 was an open-label, multicenter trial that enrolled patients with histologically confirmed grade 1 to 3a follicular lymphoma. Eligible patients had relapsed or refractory disease after receiving at least 2 prior systemic therapies, including an anti-CD20 antibody and an alkylating agent, and were required to have an ECOG performance status of 0 or 1.³

Patients were treated with either intravenous (IV) or subcutaneous mosunetuzumab. In the IV cohort (n = 90), dosing was administered on days 1, 8, and 16 of cycle 1 at 1 mg, 2 mg, and 60 mg, respectively; on day 1 of cycle 2 at 60 mg; and on day 1 of cycles 3 through 8 at 30 mg. In the subcutaneous cohort (n = 94), mosunetuzumab was given at 5 mg, 45 mg, and 45 mg on days 1, 8, and 15, respectively, of cycle 1; and at 45 mg on day 1 of cycles 2 through 8. Patients in either arm who achieved a partial response or stable disease after cycle 8 were eligible to continue treatment through cycle 17 using the cycle 8 dosing schedule.

What additional efficacy and safety outcomes were observed with subcutaneous mosunetuzumab?

Findings from the primary analysis of GO29781 presented during the 2025 SOHO Annual Meeting showed that the median DOR in the subcutaneous arm was 22.8 months (95% CI, 18.8-not evaluable [NE]). The median progression-free survival was 23.7 months (95% CI, 14.6-NE), and the median OS was not reached (95% CI, NE-NE). All the prespecified efficacy measures in the subcutaneous arm were similar to those in the IV arm.

Regarding safety, any-grade adverse effects (AEs) were reported at a rate of 98.9% in the subcutaneous arm. Patients in this arm also experienced grade 3 to 4 AEs (48.9%), serious AEs (39.4%), grade 5 AEs (5.3%), and AEs leading to discontinuation of mosunetuzumab (7.4%). Any-grade CRS occurred in 29.8% of patients. The median duration of CRS in this arm was 2 days (range, 1-15). All instances of CRS resolved in both arms.

“Since follicular lymphoma often requires lifelong management, reducing the burden of care for these individuals is of paramount importance,” Levi Garraway, MD, PhD, chief oedical Officer and head of Global Product Development at Roche, added in the news release.¹ “With this FDA approval, treatment can now be administered in just 1 minute, which significantly reduces the time patients spend in the clinic and helps to align care with their individual needs and preferences.”

References

1. FDA approves Roche’s Lunsumio VELO for subcutaneous use in relapsed or refractory follicular lymphoma. News release. Roche. December 21, 2025. Accessed December 22, 2025. https://www.roche.com/media/releases/med-cor-2025-12-22
2. European Commission approves Roche’s Lunsumio subcutaneous for relapsed or refractory follicular lymphoma. News release. Roche. November 18, 2025. Accessed December 22, 2025. https://www.roche.com/media/releases/med-cor-2025-11-19
3. Bartlett NL, Sehn LH, Assouline S, et al. Fixed-duration subcutaneous mosunetuzumab (Mosun SC) leads to high rates of durable responses, low rates of cytokine release syndrome (CRS), and non-inferior exposure compared with intravenous administration in patients with relapsed/refractory (R/R) follicular lymphoma (FL): primary analysis of a pivotal phase 2 study. Clin Lymphoma Myeloma Leuk. 2025;25(suppl 1):S821. doi:10.1016/S2152-2650(25)02418-8