The NICHE-3 phase II trial assessed neoadjuvant nivolumab (anti-PD-1) with relatlimab (anti-LAG-3) in locally advanced dMMR CRC, achieving pathological responses (RVT ≤ 50%) in 97% of patients, including a 68% pCR rate, while maintaining acceptable safety. The gene discussed is LAG3; the disease is colorectal carcinoma.