Empire State Review Team 
A groundbreaking clinical trial funded by Stand Up To Cancer (SU2C) and led by Memorial Sloan Kettering Cancer Center (MSK) has demonstrated that immunotherapy may eliminate the need for standard treatments such as surgery, chemotherapy, and radiation in patients with certain types of solid tumors. The study, published in the New England Journal of Medicine and presented at the 2025 American Association for Cancer Research Annual Meeting, reveals that 80% of trial participants did not require standard treatments after six months of immunotherapy alone.
Study Design and Findings
The phase 2 trial included 103 patients with stage 1–3 solid tumors harboring mismatch repair deficiency (MMRd), a genetic defect that impairs DNA repair mechanisms and makes tumors more susceptible to immunotherapy. Of the participants, 49 had rectal cancer, and 54 had other MMRd cancers, including gastroesophageal, hepatobiliary, colon, genitourinary, and gynecologic cancers. The treatment involved the immunotherapy drug dostarlimab (Jemperli), administered intravenously every three weeks over nine sessions.
Remarkably, all 49 rectal cancer patients experienced complete clinical responses, meaning their tumors disappeared without the need for surgery, chemotherapy, or radiation. Among the 54 patients with other MMRd cancers, 35 achieved complete remission, and nearly two-thirds preserved their organs and quality of life. Overall, 80% of participants avoided standard treatments, highlighting the potential of immunotherapy as a less invasive and effective alternative.
Implications and Future Directions
This study marks the first time that immunotherapy has been shown to replace surgery for a variety of solid tumors. The results suggest that immunotherapy could become a standard treatment option for patients with MMRd cancers, offering a less invasive approach with fewer side effects. The success of this trial builds upon previous research at MSK, where all rectal cancer patients treated with dostarlimab experienced complete tumor disappearance without standard therapies.
While the findings are promising, the applicability of this treatment is currently limited to patients with MMRd tumors, which account for approximately 2–3% of all solid tumors. Researchers are now investigating why rectal tissue responds so well to immunotherapy and how this knowledge can be applied to other cancer types. Further studies are also exploring the combination of dostarlimab with other immunotherapy agents to enhance treatment efficacy.
The FDA has granted dostarlimab a Breakthrough Therapy Designation for treating MMRd rectal cancers, potentially expediting its approval and availability for patients. As research progresses, this innovative approach may redefine cancer treatment paradigms, emphasizing organ preservation and improved quality of life for patients.
For more information on the clinical trial and its outcomes, visit the Stand Up To Cancer website.
