The U.S. Food and Drug Administration (FDA) has accepted a supplemental Biologics License Application (sBLA) for mosunetuzumab (Lunsumio VELO) in combination with polatuzumab vedotin (Polivy) for the treatment of adults with relapsed or refractory (R/R) large B-cell lymphoma (LBCL), including diffuse large B-cell lymphoma (DLBCL), who have received at least one prior systemic therapy. The application is supported by the phase 3 SUNMO trial, in which the chemotherapy-free combination reduced the risk of disease progression or death by 59% compared with R-GemOx. The FDA has set a target action date of February 9, 2027.

Clinical Takeaway

✔ The FDA has accepted the sBLA for mosunetuzumab plus polatuzumab vedotin, a chemotherapy-free, bispecific antibody plus antibody-drug conjugate combination, in R/R LBCL patients ineligible for autologous stem cell transplant (ASCT).

✔ The combination reduced the risk of disease progression or death by 59% (HR 0.41) and prolonged progression-free survival (PFS), achieving a median PFS of 11.5 months versus 3.8 months with R-GemOx in the phase 3 SUNMO trial.

✔ A regulatory decision is anticipated by February 9, 2027, which, if approved, could provide a novel non-chemotherapy backbone option for a difficult-to-treat patient population.

Drug Profile & Mechanism

  • Mosunetuzumab (Lunsumio VELO):
    • A CD20 × CD3 bispecific antibody that redirects T cells to recognize and eliminate CD20-expressing malignant B cells
    • Administered via subcutaneous (SC) injection in this combination regimen
  • Polatuzumab Vedotin (Polivy):
    • An antibody-drug conjugate (ADC) targeting CD79b, delivering a cytotoxic payload directly into lymphoma cells upon internalization
    • Administered via intravenous (IV) infusion

Target Population

  • Indication: Adult patients with relapsed or refractory large B-cell lymphoma (LBCL), including diffuse large B-cell lymphoma (DLBCL)
  • Prior therapy requirement: At least one prior systemic therapy
  • Transplant eligibility: Patients who are ineligible for autologous stem cell transplant (ASCT), representing a population with limited curative options under current standard-of-care regimens

Study Design

  • Trial name: SUNMO (phase 3)
  • Experimental arm: Subcutaneous mosunetuzumab in combination with intravenous polatuzumab vedotin
  • Comparator arm: Standard salvage regimen of rituximab, gemcitabine, and oxaliplatin (R-GemOx)
  • Population: Adults with R/R LBCL who are ineligible for ASCT and have received at least one prior systemic therapy
  • Sponsor: Roche
  • Median follow-up: 23.2 months

Efficacy Outcomes

  • The mosunetuzumab plus polatuzumab vedotin combination reduced the risk of disease progression or death by 59% (HR 0.41; 95% CI, 0.28–0.61; P < .0001) compared with R-GemOx.
  • The combination achieved a median progression-free survival of 11.5 months versus 3.8 months with R-GemOx.
  • These findings from the SUNMO phase 3 trial served as the primary basis for the sBLA submission accepted by the FDA
  • The safety profile was consistent with the known safety profiles of the individual agents, with cytokine release syndrome occurring in approximately one in four patients and fewer than 5% experiencing Grade 2 or 3 CRS.

Regulatory Context

  • Application type: Supplemental Biologics License Application (sBLA)
  • Applicant: Roche, the manufacturer of both mosunetuzumab and polatuzumab vedotin
  • FDA target action date (PDUFA date): February 9, 2027
  • FDA acceptance of the sBLA confirms the application is sufficiently complete for substantive review; approval is not guaranteed at this stage
  • Updated SUNMO data presented at the 2026 ASCO Annual Meeting and 2026 EHA Congress continued to demonstrate progression-free survival benefit with no new safety signals.

Key Clinical Implications

✔ A chemotherapy-free doublet option may be on the horizon for transplant-ineligible patients with R/R LBCL, a population that historically has had limited access to effective salvage regimens.

✔ The combination pairs two distinct, targeted mechanisms—T-cell redirection via CD20 × CD3 bispecific engagement and CD79b-directed cytotoxic payload delivery—potentially offering complementary antitumor activity without the myelosuppressive burden of traditional chemotherapy backbones.

✔ The subcutaneous formulation of mosunetuzumab, combined with intravenous polatuzumab vedotin, offers a chemotherapy-free, outpatient-ready regimen that may expand access to treatment in community oncology practices.

✔ Oncology HCPs should monitor the February 2027 PDUFA date and review the full SUNMO efficacy and safety dataset as it becomes available, to inform treatment planning for transplant-ineligible R/R LBCL patients.

Bottom Line

The FDA’s acceptance of the sBLA for mosunetuzumab plus polatuzumab vedotin marks a meaningful regulatory milestone for patients with relapsed or refractory large B-cell lymphoma who are ineligible for autologous stem cell transplant. Supported by phase 3 SUNMO data demonstrating a 59% reduction in the risk of disease progression or death and nearly tripling median progression-free survival compared with R-GemOx, this chemotherapy-free combination now moves into substantive FDA review. A regulatory decision is expected by February 9, 2027.

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