Breaking Down The SUNMO Trial on M-Pola in ASCT-Ineligible R/R LBCL

Following a presentation on recently published results from the phase 3 SUNMO trial (NCT05171647) at the Society of Hematologic Oncology 2025 Annual Meeting, presenting study author Adam J. Olszewski, MD, spoke with CancerNetwork®.

These results from SUNMO, a randomized, open-label trial, were based on the evaluation of mosunetuzumab-axgb (Lunsumio) in combination with polatuzumab vedotin-piiq (Polivy; M-Pola) compared with rituximab (Rituxan) plus gemcitabine and oxaliplatin (R-GemOx) in patients with autologous stem cell transplant-ineligible relapsed/refractory large B-cell lymphoma.

The trial showed that M-Pola achieved a 59% reduction in the risk of progression or death compared with R-GemOx (HR, 0.41; 95% CI, 0.28-0.61; P <.0001).

Olszewski, an associate professor of medicine at The Warren Alpert Medical School of Brown University, broke down the rationale and design of the trial.

Transcript:

Why was M-Pola compared with R-GemOx in ASCT-ineligible relapsed/refractory large B-cell lymphoma?

Olszewski: There is still a high unmet need for patients who have relapsed/refractory large B-cell lymphoma and who are unable to access or undergo potentially curative treatments. Historically, this involves chemotherapy and autologous stem cell transplantation, and now, more commonly in the US, [it is] CAR T-cell therapy. Studies show that a substantial proportion of patients are unable to access this treatment, or, for different reasons, are ineligible to get it. We had previously shown in a phase 2 trial that the combination of mosunetuzumab with polatuzumab vedotin provided high response rates, which appeared to be durable, and that led to the global effort to provide this therapy as an experimental arm for a global phase 3 trial comparing it with R-GemOx, which is a commonly prescribed chemotherapy regimen for these patients. This trial was conducted in multiple countries across many continents, and this treatment was delivered safely [in outpatient settings] for the 208 patients enrolled in this trial. With positive results, we think that this will create an additional option for these patients beyond R-GemOx chemotherapy, which, admittedly, is suboptimal, as we have known for many years.

How was this trial designed?

Patients had to have at least 1 line of prior therapy, and about 40% of patients had only 1 line of prior therapy. About 60% of patients on this trial were refractory to their primary therapy. These were patients who were relapsing soon after completing their [rituximab, cyclophosphamide, doxorubicin hydrochloride, vincristine sulfate, and prednisone] or [other] first-line treatment. This trial, [unlike] some other recently reported trials, enrolled high-grade B-cell lymphomas, apart from diffuse large B-cell lymphoma, as well as transformed lymphomas and grade IIIb follicular lymphoma. Patients were randomly assigned in a 2:1 ratio between the experimental regimen, which involves subcutaneous mosunetuzumab for 8 cycles and intravenous polatuzumab vedotin using standard familiar doses of 4 to 6 cycles. The comparator arm was the R-GemOx delivered by design every 14 days, although in some patients it was delayed up to every 21 days. The study enrolled a total of 208 patients. This was a fixed-duration therapy, so all patients in the experimental arm completed therapy after 8 cycles of mosunetuzumab.

Reference

Westin J, Zhang H, Kim W, et al. Mosunetuzumab plus polatuzumab vedotin is superior R-GemOx in transplant-ineligible patients with R/R LBCL: primary results of the phase III SUNMO trial. Presented at the Society of Hematologic Oncology 2025 Annual Meeting; September 3-6, 2025; Houston, TX. Abstract ABCL-1492.