Short-term surgical outcomes following neoadjuvant immunotherapy in mismatch repair-deficient colorectal cancer: initial experience from a tertiary referral center.

purposeImmunotherapy has demonstrated remarkable efficacy in mismatch repair-deficient (MMR-D) colorectal cancer (CRC). Due to their significant response rates, immune checkpoint inhibitors have emerged as a promising neoadjuvant therapy. However, data regarding short-term surgical outcomes following immunotherapy remain limited. The aim of this study is to evaluate the safety and feasibility of surgical resection after immunotherapy, as well as its short-term clinical outcomes.

methodsA retrospective review of prospectively collected data was performed at a tertiary referral center from January 2020 to July 2024. Fifteen consecutive patients with MMR-D CRC treated with pembrolizumab were analyzed. The patients' demographics, tumor characteristics, clinical outcomes, and histopathological responses were assessed.

resultsIn total, 15 patients diagnosed with MMR-D locally advanced or metastatic colorectal cancers received neoadjuvant immunotherapy followed by surgery. Of the 15 patients, 11 (73.3%) were male, 12 (80.0%) presented with T3/T4 tumors, and 3 (20.0%) had metastatic disease at diagnosis. The median number of immunotherapy cycles was 5 (range, 3-13). Surgery was performed without any anastomotic leaks or 30-day mortality. The median length of hospital stay was 5 days (range, 3-14 days). All surgical specimens had negative resection margins. Major pathological response was observed in 11 patients (73.3%), including complete response in 8 (53.3%) and near-complete response in 3 (20.0%). The median follow-up was 14 months (range, 1-56 months). One patient developed liver metastasis, which was successfully resected.

conclusionsSurgical resection of MMR-D CRC following neoadjuvant immunotherapy is safe and associated with low morbidity. Neoadjuvant immunotherapy in MMR-D CRC facilitates high rates of major pathological response.