Swim Across America-backed research helps drive FDA approval for rectal cancer immunotherapy

The FDA has granted accelerated approval to Jemperli for certain adults with locally advanced rectal cancer, based on MSK-led research that drew early support from Swim Across America. The decision marks a first-of-its-kind immunotherapy indication for this patient group and could help eligible patients avoid chemotherapy, radiation and surgery.

Why it matters: - The approval gives certain rectal cancer patients a new treatment option that can eliminate detectable cancer without chemotherapy, radiation or surgery. - The decision could help patients preserve bowel, bladder and sexual function, fertility and independence. - The milestone also shows how early nonprofit funding can help move research from the lab to FDA approval.

What happened: - The U.S. Food and Drug Administration granted accelerated approval on Oct. 19, 2026, to Jemperli (dostarlimab) for adults with stage II or III locally advanced rectal cancer whose tumors are microsatellite instability-high (MSI-H) or mismatch repair-deficient (dMMR). - The treatment was developed through research at Memorial Sloan Kettering Cancer Center, with early support from Swim Across America. - The approval is the first for an immunotherapy specifically indicated for this rectal cancer patient population.

The details: - The approval was based primarily on AZUR-1, an international trial of 154 previously untreated patients with stage II or III MSI-H/dMMR locally advanced rectal cancer. - The FDA said 110 patients, or 71%, received dostarlimab alone without additional cancer treatment or disease progression during the assessment period. - The trial showed sustained complete clinical responses in a substantial proportion of patients. - Earlier MSK research led by Luis Diaz Jr., MD, and Andrea Cercek, MD, showed that immunotherapy alone could eliminate tumors in patients with specific genetic characteristics. - Those results were reported in The New England Journal of Medicine in June 2022 and April 2025. - In the initial trial, all 12 rectal cancer patients treated with dostarlimab had a complete clinical response. - None of those 12 patients needed chemotherapy, radiation or surgery during the initial follow-up. - The expanded study published in April 2025 included 103 patients with stage I-III cancers: 49 with rectal cancer and 54 with other cancers, including gastroesophageal, hepatobiliary, colon, genitourinary and gynecologic cancers. - About 80% of the expanded-study patients avoided surgery after immunotherapy. - Swim Across America funded early research and clinical trials through its support of the Swim Across America Lab at MSK, including backing from Swim Across America – Long Island Sound and Swim Across America – Nassau-Suffolk. - The research team also received support from the National Institutes of Health, National Cancer Institute, Stand Up To Cancer and other partners. - GSK provided the immunotherapy used in the trials.

Between the lines: - The approval reflects a broader shift in cancer care toward matching treatment to tumor genetics rather than relying only on surgery, radiation and chemotherapy. - For patients with MSI-H/dMMR tumors, the data suggest immunotherapy can sometimes replace more invasive treatment. - Rob Butcher, CEO of Swim Across America, said the approval shows how early investments in promising science can lead to treatments that transform lives. - Dr. Diaz said Swim Across America grants were critical to the initial study and to advancing the trial to phase 2. - Dr. Cercek said the study shows immunotherapy can replace surgery, radiation and chemotherapy for mismatch repair-deficient solid tumors. - Dr. Cercek also said preserving quality of life while eliminating cancer is the best possible outcome. - Dr. Cercek said some patients later became pregnant and had babies after treatment, a milestone previously considered unlikely after traditional therapy. - Swim Across America-supported research has contributed to four earlier FDA-approved immunotherapies: ipilimumab (Yervoy), nivolumab (Opdivo), pembrolizumab (Keytruda) and atezolizumab (Tecentriq). - Jemperli is now the fifth immunotherapy milestone tied to Swim Across America-supported research.

What's next: - Continued clinical follow-up and confirmatory research will be needed to establish the treatment's long-term benefits. - Researchers will keep studying how far this immunotherapy approach can extend beyond rectal cancer. - Swim Across America says it will keep funding cancer research, clinical trials and patient programs through charity swims nationwide.

The bottom line: - A patient-funded research pipeline helped deliver a first-in-class immunotherapy approval that could spare some rectal cancer patients from the harshest standard treatments.