Although immunotherapy has limited impact on BTC,9 a report by Tran et al. demonstrated that adoptive transfer of tumour-infiltrating lymphocytes can mediate BTC regression.10,11 In a separate study investigating patients with high programmed cell death ligand 1 (PD-L1) expression in tumours, programmed cell death protein 1/PD-L1 blockade had efficacy as monotherapy.12 These data suggest that it is possible to elicit potent antitumour immunity against BTC. The gene discussed is PDCD1; the disease is neoplasm.