A groundbreaking study led by Dr. Andrea Cercek at Memorial Sloan Kettering Cancer Center reveals that the immunotherapy drug dostarlimab can effectively shrink tumors and eliminate detectable cancer in a majority of patients with certain genetic mutations, potentially allowing them to avoid surgery and other invasive treatments. In an early trial involving patients with rectal cancer, all 42 participants treated with monthly infusions of dostarlimab became cancer-free, with some remaining in remission for up to four years. Encouraged by these results, Cercek expanded the study to include other cancers such as colon, esophageal, stomach, urothelial, small bowel, endometrial, and gastroesophageal junction cancers.
Among patients with non-rectal cancers, 64% showed no evidence of residual disease after one year, and overall, 92% of all patients treated-including both rectal and non-rectal cases-had no cancer recurrence after two years. Even those who experienced recurrence saw reductions in tumor size or number. The treatment works by unleashing the body’s immune system to recognize and attack cancer cells, specifically targeting tumors with mismatch repair deficiency (MMRd) or microsatellite instability-high (MSI-H) genetic profiles.
Patients like 71-year-old Maureen Sideris, diagnosed with gastroesophageal junction cancer, opted for this experimental immunotherapy over traditional surgery, chemotherapy, and radiation, finding the treatment relatively easy with manageable side effects such as fatigue and skin rashes. The approach not only spares patients from the physical and emotional toll of surgery and radiation but also preserves organ function and quality of life.
Based on these compelling findings, the National Comprehensive Cancer Network has incorporated dostarlimab into treatment guidelines for cancers with the relevant genetic mutations, and the U.S. Food and Drug Administration has granted the drug fast track and breakthrough therapy designations. Cercek and her team continue to follow patients to assess long-term outcomes and are investigating how to extend benefits to those who do not initially respond.
This research marks a significant step forward in cancer treatment, demonstrating the potential of immunotherapy to replace traditional, more invasive therapies in genetically defined patient populations, offering hope for less toxic and more effective cancer care.