This phase 2 proof-of-concept study assessed the combination of 2 pharmacodynamic doses of navarixin plus pembrolizumab in 3 distinct cohorts of patients with advanced or metastatic CRPC, microsatellite-stable CRC (MSS CRC), and PD-(L)1–refractory NSCLC who were not predicted to benefit from PD-1 blockade alone. The gene discussed is CD274; the disease is non-small cell lung carcinoma.