13P First-line CEMiplimab in metastatic PENile squamous cell carcinoma: The CemPen study

Platinum-based chemotherapy has shown benefits in the first-line (1-L) setting in patients (pts) with metastatic penile squamous cell carcinoma (pSCC). Nevertheless, immune checkpoint inhibitors (ICI) have reported adequate tumor response with more acceptable safety. Among ICI, cemiplimab (C) received approval for advanced cutaneous SCC (cSCC) and for advanced cervical cancer. pSCC may develop on chronic Human Papilloma Virus (HPV) infection, similarly to cervical SCC. Because of similarities between cervical and penile SCC, C might represent a valid option for patients with metastatic SCC developed from cutis of penis. In light of these evidence, we have designed a retrospective study to evaluate 1-L CEMiplimab in metastatic PENile SCC (CemPen). CemPen is a retrospective, observational, monocentric study involving pts with metastatic pSCC treated with 1-L C between April 2021 and December 2023 at Careggi University Hospital. We assessed objective response rate (ORR) at 12 weeks according to iRECIST, median progression free survival (PFS), overall survival (OS), clinical benefit rate (CBR), and safety profile according to CTCAE v 5.0. Eighteen penile SCC pts were enrolled. Median age was 70 years. With a median follow up of 14 months (mo), 9 pts (50%) had discontinued C. The 12-week ORR was 11% (2 partial response [PR]), 22% of pts had stable disease (SD), with a CBR of 33%. Notably, the PR were reported in 2 metastatic HPV-negative pSCC and they are still ongoing. At the time of analysis, 9 pts (50%) had PD, the median PFS was 6.4 mo (95% CI [2.7; NR]). Moreover, 8 pts had died (all in PD), the median OS was 12.3 mo (95% CI [7.3; NR]). Overall, one patient, after two years of treatment, experienced grade 3 immune-related cutaneous rash, successfully treated with methylprednisolone 2 mg/Kg i.v. Due to his durable partial response, Cemiplimab was permanently discontinued, without progression. We report the largest known data of Cemiplimab in 1-L treatment of advanced pSCC. Data of CBR and safety are encouraging and support the use of C in this setting. Prospective studies are needed. The value of HPV status as predictive factor will be investigated.