The combination of cemiplimab-rwlc (Libtayo) with standard platinum-based chemotherapy has demonstrated promising efficacy in patients with locally advanced or metastatic penile carcinoma, according to new data from the phase 2 EPIC trial presented at the 2025 ASCO Genitourinary Cancer Symposium.
The open-label study showed impressive response rates, with a clinical benefit rate (CBR) of 62.1% (95% CI, 44.4%-79.7%) at 12 weeks. Among the 29 enrolled patients, 51.7% achieved partial responses, and 10.3% maintained stable disease, though no complete responses were observed at the 12-week mark.
Treatment Outcomes and Survival Data
The objective response rate (ORR) at 12 weeks reached 51.7% (95% CI, 34.4%-68.6%), exceeding the null hypothesis threshold of 25%. By week 21, one patient (3.4%) achieved a complete response, while 41.4% maintained partial responses. The median progression-free survival (PFS) was 6.2 months (95% CI, 3.7-8.7), with median overall survival (OS) reaching 15.5 months (95% CI, 6.0-25.0).
"These data support combination cisplatin-based chemotherapy plus cemiplimab as a first line treatment option to potentially improve outcomes in this rare cancer," stated Dr. Amit Bahl from the Bristol Haematology and Oncology Centre, University Hospitals Bristol and Weston NHS Foundation Trust.
Trial Design and Patient Characteristics
The study administered 350 mg of intravenous cemiplimab on day one of each treatment cycle, combined with four cycles of cisplatin-based chemotherapy every three weeks. Patients could then transition to maintenance therapy with cemiplimab for up to 30 cycles.
The patient population had a median age of 61 years, with 76% presenting with metastatic disease. Common metastatic sites included lung (55.2%), bone (23.0%), and liver (6.9%). Treatment duration averaged 5 cycles, with some patients receiving up to 34 cycles.
Safety and Tolerability Profile
The safety profile aligned with previously reported data for both agents. Grade 3 or higher adverse events related to chemotherapy included gastrointestinal disorders (13.6%) and blood/lymphatic system disorders (9.1%). Cemiplimab-related serious adverse events primarily involved infections and infestations (22.2%) and gastrointestinal disorders (11.1%).
Treatment discontinuation occurred in seven patients, with four cases attributed to cemiplimab. Two grade 5 adverse events were reported, with one related to chemotherapy and none to cemiplimab.
The trial's positive outcomes in this rare and challenging cancer type suggest that the combination therapy could represent a meaningful advance in the treatment landscape for advanced penile carcinoma, particularly given the limited treatment options currently available for these patients.
