Clinical Summary:

• Design/Population: The phase 3 SUNMO trial randomized transplant-ineligible patients with relapsed/refractory large B-cell lymphoma to receive subcutaneous mosunetuzumab plus polatuzumab vedotin or rituximab plus gemcitabine/oxaliplatin, including patients treated in the second-line and later-line settings.
• Key Outcomes: Mosunetuzumab plus polatuzumab vedotin continued to improve progression-free survival and response rates, with consistent benefit in both second-line and third-line or later subgroups. 
• Clinical Relevance: Mosunetuzumab plus polatuzumab vedotin may provide an effective, chemotherapy-sparing option, with particularly notable activity in the second-line setting and a favorable immune-toxicity profile.

Elizabeth Budde, MD, PhD, City of Hope Comprehensive Cancer Center, Durante, California, discusses updated results from the phase 3 SUNMO trial which demonstrated that mosunetuzumab plus polatuzumab vedotin continues to provide superior efficacy compared with rituximab, gemcitabine, and oxaliplatin among transplant-ineligible patients with relapsed/refractory large B-cell lymphoma. 

Dr Budde presented these results at the 2026 American Society of Clinical Oncology (ASCO) Annual Meeting in Chicago, Illinois. 

Transcript:

My name's Elizabeth Budde, I'm a hematologist from City of Hope National Medical Center. The ASCO presentation that I'm about to give is really looking at the phase 3 SUNMO study, which is conducting patients with relapsed/refractory large B-cell lymphoma, comparing a novel regimen mosunetuzumab in combination with polatuzumab as the experimental arm with the standard care R-GemOx.

This is a global study and it's really completely the data already being presented last year where we see mosunetuzumab plus polatuzumab has doubled the complete response rate in the same patient population comparing to GemOx. When we look at progression-free survival, mosunetuzumab plus polatuzumab also tripled the duration of progression free survival. The study met is double primary end points.

This presentation is really focusing on looking at doing deep dive, looking at subgroup analysis, and looking at those patients who enrolled on these particular clinical trials, looking at those who receive mosunetuzumab and polatuzumab in earlier line setting, meaning that in patient who received this regimen in the second-line setting, either they're refractory to the firs-tline setting or their early relapsed in this setting. Just to remind everyone, mosunetuzumab plus polatuzumab are given a total of 8 cycles. It's fixed duration, no requirement hospitalization. GemOx was also designed to give around 8 cycles of treatment.

The study randomized patients in 2:1 fashion, 2 is to the mosunetuzumab plus polatuzumab [and]1 is to the GemOx, and patient will also stratify by whether they have 1 line or more prior lines of therapy or whether they have refractory disease or they have no relapsed disease. When you look at the 2 groups, patient randomized to mosunetuzumab-polatuzumab versus patient randomized to GemOx, the baseline categories actually suggest that patient with higher percentage of patients with transform follicular lymphoma and higher percentage of patients with ECOG-2 and higher percent of patients now had bulky disease were actually in the mosunetuzumab plus polatuzumab group. But despite this, no, we see a pretty significant difference with regards to efficacy.

In those patients who received mosunetuzumab plus polatuzumab in the second-line setting, we see a median progression-free survival of 17.6 months and with a CR rate of 60.7 months. This really compared very favorably to those patients who received R-GemOx. The comparator where the median progression-free survival was only 3.6 months and CR rate was only 20%. Therefore the 2-year progression-free survival rate was doubled with mosunetuzumab plus polatuzumab versus GemOx and the median duration of response was also not reached inpatient treated with mosunetuzumab plus polatuzumab. With the longer-term follow-up, we also did not see any additional adverse events, no inpatient who received this investigational combination mosunetuzumab plus polatuzumab.

Therefore to conclude, despite some baseline imbalance of failing the control R-GemOx, the 2-year progression-free survival with mosunetuzumab-polatuzumab were more than doubled than the R-GemOx. In the secondline setting, mosunetuzumab-polatuzumab actually reduced the risk of death or progression by 62% versus RGemOx.

We also see consistent benefits also seeing those patients who receive mosunetuzumab plus polatuzumab regimen in the third-line plus setting in both younger patient or elderly patient who are older than 68 years old and we didn't really see age being a differential factor here. Again, no additional new adverse event was reported with mosunetuzumab -polatuzumab combination with this no longer additional follow-up.

Mosunetuzumab-polatuzumab is a highly effective novel targeted therapy that can be delivered across very diverse outpatient treatment centers has the potential to be the center of care in the second-line setting for patient with aggressive B-cell lymphoma.

Source:

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 subgroup. Presented at the ASCO Annual Meeting. May 29 - June 2, 2026. Chicago, Illinois. 7007.