Efficacy of pembrolizumab in a rare type of bladder cancer arising 25 years after augmentation cystoplasty.

We report using the checkpoint inhibitor, pembrolizumab, as part of a multimodal treatment plan in a 36-year-old man with a rare bladder cancer arising 25 years after augmentation cystoplasty (sigmoid colonic cystectomy for neuropathic bladder was performed at 9 years old). On a regular clinic visit for clean intermittent catheterisation, the patient presented with gross haematuria and was diagnosed with urothelial carcinoma with sarcomatoid change. Gemcitabine and cisplatin-based neoadjuvant chemotherapy was unsuccessful, and pembrolizumab infusions (200 mg every 3 weeks) were initiated. A partial response was confirmed after six courses of pembrolizumab, with significant tumour shrinkage. A radical cystoprostatectomy and ileal conduit construction was performed, and pathology revealed no evidence of malignancy (ypT0, N0). The patient was successfully treated with the anti-programmed death-1 inhibitor, pembrolizumab, which was curative after total cystectomy. Further research is required to elucidate the potential role of checkpoint inhibitors in bladder cancers arising after augmentation cystoplasty.