The first study of immune checkpoint inhibition in men with germ cell tumours found no clinically meaningful activity of the programmed cell death protein 1 inhibitor pembrolizumab. Treatment with a median of two doses (range 1–8) in 12 patients with refractory nonseminoma resulted in no partial or complete responses. Two patients had radiographically stable disease for 19 weeks and 28 weeks but displayed a continued increase in α-fetoprotein levels.