Another randomized controlled trial, Keynote 001, reported that among patients with at least 50% of tumor cells expressing PD-L1 who received the anti-PD-1 monoclonal antibody pembrolizumab, the objective response rate was 45.3%, which means that nearly half of the patients had tumor shrinkage by at least 30%; however, in patients with less than 1% of tumor cells expressing PD-L1, the objective response rate was only 10.7% [37]. The gene discussed is PDCD1; the disease is neoplasm.