ABSTRACT Introduction Avelumab maintenance after response to platinum chemotherapy improves outcomes in metastatic urothelial carcinoma. Progression during maintenance presents a therapeutic dilemma. Case Presentation A 72‐year‐old man underwent radical cystectomy and left nephroureterectomy for high‐grade urothelial carcinoma. Two and a half years later, a solitary pelvic nodal recurrence achieved complete response to gemcitabine–cisplatin, after which avelumab maintenance was started. After 16 cycles, the same node regrew, indicating progression. Pembrolizumab was initiated and induced a second complete response after four cycles. He remains recurrence‐free for three years without immune‐related adverse events. Conclusion Durable remission with pembrolizumab following progression on avelumab suggests that switching from PD‐L1 to PD‐1 blockade can overcome resistance in selected patients; prospective studies and biomarker strategies, including PD‐L2 assessment, are warranted and may guide individualized rechallenge strategies.
Ito et al. (Sun,) studied this question.