FDA Accepts SC Mosunetuzumab Combo sBLA in Relapsed/Refractory LBCL

The FDA has accepted a supplemental biologics license application (sBLA) for a subcutaneous formulation of mosunetuzumab (Lunsumio VELO) in combination with polatuzumab vedotin-piiq (Polivy) for the treatment of adult patients with relapsed/refractory large B-cell lymphoma (LBCL) following at least 1 prior line of therapy, according to a news release from the developer, Roche.¹

Moreover, the FDA has set a Prescription Drug User Fee Act date of February 9, 2027, for this indication.

Supporting the acceptance of the sBLA are data from the phase 3 SUNMO trial (NCT05171647), which evaluated the investigational regimen against rituximab (Rituxan), gemcitabine, and oxaliplatin (R-GemOx). Results were recently presented at the 2026 American Society of Clinical Oncology (ASCO) Annual Meeting and the European Hematology Association (EHA) 2026 Congress.^2,3

After a median follow-up of 23.2 months, the mosunetuzumab-based regimen elicited a 59% reduction in the risk of disease progression or death compared with the rituximab-based regimen (HR, 0.41; 95% CI, 0.28-0.61; P <.0001). The median progression-free survival (PFS) in the respective arms was 11.5 months (95% CI, 5.6-17.6) vs 3.8 months (95% CI, 2.9-4.1). Moreover, the 2-year PFS rates were 37.5% (95% CI, 28.4%-46.5%) vs 14.3% (95% CI, 2.5%-26.0%).

Regarding response data, the mosunetuzumab-based combination demonstrated an objective response rate (ORR) of 70.3% (95% CI, 61.9%-77.8%) vs 40.0% (95% CI, 28.5%-52.4%) among those treated with chemoimmunotherapy, with respective complete response (CR) rates of 51.4% (95% CI, 42.8%-60.0%) vs 24.3% (95% CI, 14.8%-36.0%). Moreover, the median duration of response (DOR) in the respective arms was 18.8 months (95% CI, 11.5-not evaluable [NE]) vs 6.0 months (95% CI, 3.7-23.9), with 2-years rates of 47.9% (95% CI, 37.0%-58.8%) vs 15.4% (95% CI, 0.0%-39.8%). Moreover, the duration of complete response (DOCR) was not reached (NR) vs 18.3 months (95% CI, 3.9-NE), respectively, with 2-year rates of 62.5% (95% CI, 50.1%-74.9%) vs 22.0% (95% CI, 0.0%-56.2%).

“When treating [LBCL], the second-line setting represents a critical window where we must act quickly with effective therapies," Tara M. Graff, DO, MS, director of Clinical Research at Mission Cancer and Blood, stated in the news release.¹ "Current advanced therapies may present complex logistical and geographical barriers for many patients. Since most patients in the US are treated in the community setting, we need more chemotherapy-free, outpatient-ready treatments, like [mosunetuzumab] and [polatuzumab vedotin]."

Patients deemed ineligible for autologous stem cell transplantation (ASCT) with relapsed/refractory disease—including diffuse LBCL not otherwise specified, transformed follicular lymphoma, high-grade BCL, and grade 3B follicular lymphoma—were randomly assigned 2:1 to receive subcutaneous mosunetuzumab plus polatuzumab vedotin or R-GemOx.

Those in the mosunetuzumab arm underwent screening and started with 5 mg of the agent on cycle 1, day 1 followed by 45 mg on days 8 and 15 plus polatuzumab vedotin on days 1 and 15. For each cycle thereafter up to cycle 8, both agents were administered on day 1 of each 21-day cycle. For patients in the R-GemOx arm, treatment was given for eight 14-to-21–day cycles. In both arms, follow-up occurred up to 30 months after treatment, and corticosteroid premedication was given prior to each dose in cycle 1 and was optional in each subsequent cycle.

In the intent-to-treat population, the median age was 62 years (range, 23-87) in the mosunetuzumab arm and 63 years (range, 29-85) in the R-GemOx arm, with 39.1% vs 45.7% of each arm being 65 years and older. A total of 13.0% vs 1.4% of each respective arm had an ECOG performance score of 2, 18.8% vs 20.0% had high-grade BCL, and 75.4% vs 80.0% had Ann Arbor stage III to IV disease. Bulky disease was observed in 20.3% vs 7.1% of each arm, primary refractory disease was observed in 57.2% vs 60.0%, and 71.0% vs 68.6% were refractory to the most recent prior therapy.

The dual primary end points were ORR and PFS per independent review committee assessment. A key secondary end point was overall survival. Safety was an additional secondary end point.

Regarding safety outcomes, no new signals were observed across either treatment arm. Cytokine release syndrome (CRS) was deemed infrequent by the investigators, with 25.9% of patients experiencing events; 1 (0.7%) patient experienced a grade 3 event. A total of 5.7% of patients experienced a serious CRS event. The median onset to CRS was 3 days (range, 1-6), with a median duration of 3 days (range, 1-11). Additionally, 4.4% and 3.7% of patients received tocilizumab (Actemra) or corticosteroids for the management of CRS, respectively.

References

1. FDA accepts supplemental biologics license application for Roche’s Lunsumio and Polivy combination for people with relapsed or refractory large B-cell lymphoma. News release. Roche. June 17, 2026. Accessed June 19, 2026. https://tinyurl.com/ydzjfr9y
2. Kim W, Wesrin J, Maruyama D, et al. Mosunetuzumab plus polatuzumab vedotin (Mosun-Pola) versus rituximab, gemcitabine and oxaliplatin (R-GemOx) in patients with relapsed/refractory large B-cell lymphoma (R/R LBCL): updated efficacy and safety from the phase 3 SUNMO study including in second-line (2L) versus third-line plus (3L+) patient subgroups. J Clin Oncol. 2026;44(suppl 15):7007. doi:10.1200/JCO.2026.44.16_suppl.7007
3. Budde E, Westin J, Maruyama D, et al. Mosunetuzumab plus polatuzumab vedotin versus rituximab, gemcitabine and oxaliplatin in large B-cell lymphoma: updated efficacy and safety from the phase 3 SUNMO study including in patient subgroups. Presented at: European Hematology Association 2026 Congress; June 11-14, 2026; Stockholm, Sweden. Abstract PF968