Balar AV, Kamat AM, Kulkarni GS, et al. - Researchers assessed pembrolizumab, a PD-1 inhibitor, in BCG-unresponsive non-muscle-invasive bladder cancer, by performing the KEYNOTE-057 study. In cohort A of this open-label, single-arm, multicentre, phase 2 study, adults aged 18 years or older with histologically verified BCG-unresponsive carcinoma in situ of the bladder, with or without papillary tumours, with an Eastern Cooperative Oncology Group performance status of 0–2, and who were ineligible for or refused radical cystectomy were included. All patients were treated with pembrolizumab 200 mg intravenously every 3 weeks for up to 24 months or until centrally proven disease persistence, recurrence, or progression; unacceptable toxic impacts; or consent withdrawal. In cohort B, there were patients with BCG-unresponsive high grade Ta or any grade T1 papillary disease without carcinoma in situ. Findings demonstrated the tolerability as well as the promising antitumour activity of pembrolizumab monotherapy in patients with BCG-unresponsive non-muscle-invasive bladder cancer who refused or were ineligible for radical cystectomy. In this difficult-to-treat population, pembrolizumab monotherapy is recommended to be considered as a clinically active non-surgical treatment choice.