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ResearchPUBMEDThursday, March 26, 2026 · March 26, 2026

Evaluation of mixed response in tumor size and survival in patients with rare cancers treated with dual checkpoint inhibitor therapy (DART SWOG S1609).

WHY IT MATTERS

Understanding mixed response patterns helps doctors better predict which rare cancer patients will benefit most from dual checkpoint inhibitor therapy and may improve how treatment success is measured beyond just tumor size.

Researchers studied how cancer tumors respond differently to a two-drug immunotherapy treatment (ipilimumab plus nivolumab) in patients with rare cancers. Some patients had some tumors shrink while others grew at the same time—called 'mixed response.' This study looked at 438 patients to understand how this mixed response affects how long patients survive and whether the cancer comes back.

Evaluation of mixed response in tumor size and survival in patients with rare cancers treated with dual checkpoint inhibitor therapy (DART SWOG S1609). Abstract: Mixed response, where different lesions within the same patient show discordant responses to treatment, remains poorly understood. To better understand the complex effects of mixed response on patient survival, we devised three different definitions of mixed response. This retrospective analysis provides the first evaluation of the association between mixed response and survival outcomes in patients with rare cancers treated with dual checkpoint blockade using ipilimumab plus nivolumab, based on data from 52 baskets in the DART SWOG S1609 trial. We included 438 patients with Response Evaluation Criteria in Solid Tumors (RECIST) V.1.1-measurable disease and at least two target lesions, after exclusions for ineligibility, early death, or missing data. Overall survival (OS) and progression-fr Authors: Chae et al. Journal: Journal for immunotherapy of cancer MeSH: Humans, Immune Checkpoint Inhibitors, Male, Female, Neoplasms, Middle Aged, Retrospective Studies, Aged, Nivolumab, Adult

ASK YOUR DOCTOR

If you have a rare cancer and are considering or currently receiving ipilimumab plus nivolumab therapy, ask your oncologist how they monitor mixed responses and what it means for your individual treatment plan.

Find a specialist →Learn more ↗
immunotherapycheckpoint inhibitorsmixed responserare cancersclinical trial

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