Profound and durable responses with PD-1 immune checkpoint inhibitors in patients with metastatic penile squamous cell carcinoma

Abstract Introduction Penile squamous cell carcinoma (pSCC) is a rare disease characterized by a dismal prognosis in advanced stages. Systemic treatment options are very limited, and there is no standard treatment after progression on first line chemotherapy. Patients and methods We report two patients with chemotherapy-refractory metastatic penile SCC, who were treated with PD-1 inhibitor cemiplimab (case 1) or pembrolizumab (case 2). Both cases were HPV-positive and showed high expression of PD-L1. Results Despite intensive pretreatment partial remission was achieved in both cases with prolonged duration of response of >10 months (patient 1) and >27 months (patient 2), respectively. Conclusions These results suggest a high susceptibility of penile SCC to immune checkpoint inhibitor therapies. Since there is a high unmet need for this clinical situation, prospective evaluation of immunotherapy is urgently needed.