Pembrolizumab for advanced penile cancer: a case series from a phase II basket trial.

BACKGROUND

Treatment options for unresectable, locally advanced or metastatic penile squamous cell carcinoma (SCC) are limited. Previous studies have shown that 40-62% of patients with penile SCC express PD-L1. We report three cases of locally advanced or metastatic penile SCC treated with pembrolizumab.

CASE PRESENTATIONS

Herein, we present three patients with recurrent, locally advanced or metastatic penile SCC who progressed on a platinum-based chemotherapy triplet and were treated with pembrolizumab, administered as part of a phase II clinical trial for rare tumors (NCT02721732). One patient with a microsatellite instability high (MSI-H) tumor experienced a durable partial response to pembrolizumab, underwent surgical consolidation, and remains disease-free 38.7 months later. Two patients experienced progressive disease within 3 months of beginning pembrolizumab. No one experienced a grade 3 or worse treatment-related adverse event.

CONCLUSION

In sum, single-agent pembrolizumab was well tolerated as salvage therapy in a small cohort of patients with unresectable, locally advanced or metastatic penile SCC. Pembrolizumab produced an objective response in an MSI-H tumor, yet it did not control disease in two patients with MSS penile SCC. Rationale combination therapies, including pembrolizumab, warrant further investigation.

TRIAL REGISTRATION

ClinicalTrials.gov identifier: NCT02721732 . Registered March 23, 2016.