Is there a long-term benefit to immunotherapy in colorectal cancer?

Linda H. Rodgers-Fouché - CGA-IGC Research Committee

Credit: National Cancer Institute, National Institutes of Health - https://creativecommons.org/licenses/by-nc/2.0/legalcode

Immunotherapy has garnered much excitement from researchers, oncologists, and cancer patients since its early days. It offers a new paradigm in cancer care where the immune system’s natural cancer-fighting abilities are aided and enhanced. Recent studies have demonstrated immunotherapy (e.g., immune checkpoint therapy) improves survival for patients with microsatellite instability-high (MSI-H) advanced colorectal cancer (CRC). In most cases, immunotherapy is discontinued after two years, yet there is little data on survival and recurrence for patients after ending treatment.

Dr. Kristen Simmons of Baylor College of Medicine and colleagues sought to determine outcomes of patients with MSI-H advanced CRC after discontinuing immunotherapy.

Thirty-six patients who did not progress while on immunotherapy were reviewed. Impressively, 30 of 36 (83%) of patients had no disease progression after a median of 19 months (95% CI, 14-26). Six patients had disease progression with a median time to progression of 13 months (range: 5-31). The estimated 1-year, 2-year, and 3-year disease-free survival probabilities were 90% (95% CI, 79-100), 79.1% (95% CI, 64-98), and 68% (95% CI, 47-98), respectively. From the time immunotherapy was stopped, the overall median survival was 54 months (95% CI, 47-NA).

Dr. Simmons presented these findings at the Collaborative Group of the Americas on Inherited Gastrointestinal Cancers (CGA-IGC) Annual Meeting in Nashville, TN, on November 12, 2022, as part of a Presidential Plenary session. Dr. Simmons explained, “For patients with MSI-H/dMMR metastatic or unresectable colorectal cancer, discontinuation of immunotherapy after two years of disease control is currently a widely accepted practice pattern despite the lack of literature regarding patient outcomes after stopping treatment. Our retrospective, single-institution analysis showed that most of these patients did not recur after treatment cessation, regardless of the reason for stopping treatment and a variety of patient and disease characteristics. We hope this data will provide critical clinical information that can be used by oncologists to counsel similar patients considering stopping immunotherapy after initial clinical benefit”.

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