The Checkmate 067 trial of dual checkpoint blockade (CTLA-4/PD-1) in advanced melanoma showed a response rate of 58%, with a 52% 5-year survival in a historically poor-prognosis group (7), and patients with a complete response were shown to have a less than 10% chance of relapse on discontinuation of treatment in a study by Robert et al. Here, PDCD1 is linked to melanoma.