# Complete Response to Pembrolizumab After Progression on Avelumab Maintenance in Metastatic Urothelial Carcinoma

## TL;DR

A patient with advanced bladder cancer achieved a complete response to pembrolizumab after progressing on avelumab, suggesting that switching immunotherapy drugs can overcome resistance.

## Contribution

Demonstrates that switching from PD-L1 to PD-1 inhibitors may overcome resistance in metastatic urothelial carcinoma.

## Key findings

- The patient achieved a complete response to pembrolizumab after progressing on avelumab.
- He remained recurrence-free for three years without immune-related adverse events.
- The case suggests that PD-L2 assessment and biomarker strategies may guide rechallenge decisions.

## Abstract

Avelumab maintenance after response to platinum chemotherapy improves outcomes in metastatic urothelial carcinoma. Progression during maintenance presents a therapeutic dilemma.

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.

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.