This phase 2 trial (NICHE-3) investigated the efficacy and safety of neoadjuvant nivolumab (480 mg) plus relatlimab (480 mg) in 59 patients with locally advanced mismatch repair-deficient (dMMR) colon cancer. A pathologic response was observed in 97% of patients, including 92% with major pathologic responses (≤10% residual viable tumor) and 68% with pathologic complete responses. One patient experienced disease recurrence at a median follow-up of 8 months. The treatment showed an acceptable safety profile, with 80% experiencing any-grade immune-related adverse events (irAEs) and 10% grade 3-4 irAEs. These results suggest that neoadjuvant nivolumab/relatlimab is highly effective and warrants further investigation in larger studies.

Peter G. M. de Gooyer, Yara L. Verschoor, Lauren D. W. van den Dungen, Sara Balduzzi, Hendrik A. Marsman, Marnix H. Geukes Foppen, Cecile Grootscholten, Simone Dokter, Anne G. den Hartog, Wieke H. M. Verbeek, Karlijn Woensdregt, Joris J. van den Broek, Steven J. Oosterling, Ton N. Schumacher, Koert F. D. Kuhlmann, Regina G. H. Beets-Tan, John B. A. G. Haanen, Monique E. van Leerdam, Jose G. van den Berg, Myriam Chalabi