Sharma et al. observed better tumour control and survival in two melanoma models of simultaneous administration of anti-PD-1 and hydroxychloroquine126, while in a comparable model, Krueger et al. observed impaired tumour control when hydroxychloroquine was initiated 5 days after first anti-PD-1 initiation, again underlining the importance of timing128. The gene discussed is PDCD1; the disease is melanoma.