SUNMO: ADC Plus Bispecific Yields Double PFS of Chemotherapy at 2 Years in R/R LBCL, With Lowest CRS Rate Seen

New data from the phase 3 SUNMO trial (NCT05171647), presented at the 2026 American Society of Clinical Oncology (ASCO) Annual Meeting,¹ confirm mosunetuzumab (Lunsumio; Genentech) plus polatuzumab vedotin (Polivy; Genentech) as a compelling chemotherapy-free option for patients with relapsed/refractory large B-cell lymphoma (R/R LBCL) who are ineligible for autologous stem cell transplant, particularly those receiving the combination as second-line therapy.

Results showed that at a median follow-up of 28.3 months, the combination known as mosun-pola continued to demonstrate superior progression-free survival (PFS) over R-GemOx (rituximab, gemcitabine, oxaliplatin) across the full trial population (HR, 0.41; 95% CI, 0.28-0.60). The overall response rate (ORR) was 70.3% with mosun-pola vs 40.0% with R-GemOx.

Second-line subgroup data are particularly compelling, in view of other data presented during ASCO. Among the 91 patients who had received 1 prior line of therapy, including those who were primary refractory or experienced early relapse, the ORR with mosun-pola was 75.4% vs 36.7% with R-GemOx, and the complete response (CR) rate was 60.7% vs 20.0%. The 2-year PFS rate was 40.3% vs 20.1%—effectively double—and the 2-year duration of CR estimate was 60.8% vs 37.5%. Median duration of CR was not reached in either the second-line or third-line+ mosun-pola subgroups. The PFS benefit was consistent across both second-line (HR, 0.38) and third-line+ (HR, 0.48) subgroups.

The safety profile was unchanged from the primary analysis. Grade 2 or greater cytokine release syndrome (CRS) occurred in just 4% of mosun-pola patients overall, and no immune effector cell–associated neurotoxicity syndrome events were observed. In the second-line subgroup, grade 2 CRS occurred in 3%, and no grade 3 or greater CRS events were recorded.

Elizabeth Budde, MD, PhD, hematologist-oncologist at City of Hope and senior author of the study, presented the findings. Budde noted in an interview with The American Journal of Managed Care^® (AJMC®) that mosun-pola carries the lowest CRS incidence among bispecific antibody–based regimens and that most CRS events are low-grade, self-limited, and manageable with acetaminophen or ibuprofen in the outpatient setting.

Additional insights from Budde’s interview appear below.

This transcript has been lightly edited.

AJMC: What were the goals of the SUNMO study, which compared use of the combination of the antibody-drug conjugate (ADC) polatuzumab vedotin and the bispecific antibody mosunetuzumab (mosun-pola) vs the chemotherapy-based combination of R-GemOx (rituximab, gemcitabine, oxaliplatin) in LBCL?

Budde: The main goal of the presentation at ASCO is to look at this regimen in the second-line setting—what is the outcome? This presentation is really looking at the response rate and progression-free survival in second-line use; the overall survival data are not mature yet.

AJMC: What did the data show for outcomes in the second-line setting?

Budde: The overall advantage of this regimen compared to regular chemotherapy in the second-line setting, as [we look] at those patients in the second-line setting, the data actually looked even better when you just narrow down to those patients who received this regimen that either they didn’t respond to the first-line treatment or responded to the first-line treatment, but relapse very, very quickly—we call those early relapse patients.

Among those patients in the second-line setting, the overall response rate is 75%. The complete response rate is now 61%, and compared to patients who were randomly assigned to R-GemOx, the control arm, the hazard ratio is actually very low, 0.38. So, the lower the HR, the more significant this is. When you use this regimen in the second-line setting, we see that the 2-year progression for survival rates, at 40%, is double of that for patients who were randomly assigned to the control arm, which was 20%.

AJMC: How do the ADC and the bispecific work together to fight the cancer in LBCL?

Budde: Each therapy has its mechanisms of action. Now, the bispecific recruits the endogenous T cells to the site by redirecting to CD20-positive target cells. And then polatuzumab, the antibody-drug conjugate, targets CD79b [protein] at the same time, but it doesn’t rely on the effective cell function. So, what it does, it carries a warhead, and then once you get to the target cells, basically the warhead gets dumped inside the cell, so you just know it turns off the cells now via a different mechanism. So, by attacking the lymphoma cells from 2 different targets with 2 different mechanisms, it’s just really making it harder for the lymphoma cells to survive. Also, there are some preclinical data demonstrating that polatuzumab, this ADC, can actually sensitize the target cell to be more susceptible to the bispecific antibody–mediated killing, so there is a synergistic effect.

AJMC: The trend today is to move bispecific delivery into the outpatient setting. What are some advantages of mosun-pola in administration of this combination therapy vs R-GemOx? Is this a good choice for outpatient administration?

Budde: Oh, absolutely. So, this combination, this regimen, is meant for the outpatient setting. For patients randomized to [mosun-pola], there’s no requirement for hospitalization, and in fact, this is the default outpatient regimen, and patients do quite well. This is also the bispecific monotherapy or bispecific combination regimen that has the lowest cytokine release syndrome incidence; with a majority of [cases] actually very low-grade and self-limiting; these cases can typically can be taken care of easily; if there is a fever, they can take Tylenol, if blood counts are low, they can take ibuprofen. That typically would take care of it, so it’s quite safe. And you know, we’re talking about in a clinical trial setting; the oldest patient was in their 80s, but in real life, the oldest patient treated with this regimen was in their 90s.

Reference

Kim W, Westin 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 16):7007. doi:10.1200/JCO.2026.44.16_suppl.7007