Early radiologic signal of responsiveness to immune checkpoint blockade in MSS/pMMR metastatic colorectal cancer

Immune checkpoint blockade (ICB) results in radiologic tumor response dynamics that differ from chemotherapy efficacy measures and require an early sign of clinical utility. A phase 2 study in Norway found that radiologic reduction of target lesions of ≥ 10% at the first post-baseline response assessment identified patients with ICB-responsive metastatic microsatellite-stable/mismatch repair-proficient colorectal cancer. The authors conclude that this pragmatic measure may be used to monitor patients in investigational ICB schedules, enabling early treatment adaptation for unresponsive cases.