First-line therapy with dacomitinib, an orally available pan-HER tyrosine kinase inhibitor, for locally-advanced or metastatic penile squamous cell carcinoma: results of an open label, single-arm, single-center, phase 2 study

To harness the frontline therapy in advanced penile squamous cell carcinoma (PSCC), for which chemotherapy exerts moderate activity but poor efficacy. Dacomitinib is an irreversible, pan-epidermal growth factor receptor (HER) inhibitor.

In a phase 2 study (NCT01728233), patients received dacomitinib 45 mg/day, orally, continuously. Inclusion criteria were SCC histology, clinical stage N2-3 or M1 (TNM 2009), and no prior chemotherapy administration. The primary endpoint was the objective response-rate (ORR, according to RECIST v1.1). Stopping rules based on the Bayesian posterior probability (PP) to demonstrate that the ORR exceeded 20% were set.

From June 2013 to October 2016, 28 patients were treated. Eight (28.6%) had visceral metastases, 14 (50%) had pelvic and 17 (60.7%) clinically-involved bilateral lymph nodes. One complete and eight partial responses were obtained (ORR: 32.1%, 80% credibility interval 21.0-43.0%). The median follow-up duration was 19.8 months (IQR: 6.3-25.7); 12-month progression-free survival was 26.2% (95%CI: 13.2-51.9); 12-month overall survival (OS) was 54.9% (95%CI: 36.4-82.8). The median OS of locally-advanced patients was 20 months (IQR: 11.1-not reached). The Bayesian PP of exceeding the 20% ORR target was 92.3%. Grade 3 adverse events (skin rash) were seen in 3 patients (10.7%). Tissue samples from 25 patients were analyzed. Only two patients had HR-HPV-positive tumor. EGFR amplification was found in 4 patients (equally responders and non responders) and it was confirmed in all post-dacomitinib samples. TERT mutations (60%) were found in responders only, PI3K/mTOR pathway gene mutations in 42.9% responders versus 8.3% non responders.

Dacomitinib was active and well tolerated in patients with advanced PSCC and may represent an option when combination chemotherapy cannot be administered. Mutations in downstream effectors of EGFR signaling in relation to dacomitinib activity deserve further studies. This article is protected by copyright. All rights reserved.

BJU international. 2017 Sep 16 [Epub ahead of print]

A Necchi, S Lo Vullo, F Perrone, D Raggi, P Giannatempo, G Calareso, N Nicolai, L Piva, D Biasoni, M Catanzaro, T Torelli, S Stagni, E Togliardi, M Colecchia, A Busico, A Gloghini, A Testi, L Mariani, R Salvioni

Department of Medical Oncology, Fondazione IRCCS Istituto Nazionale dei Tumori., Clinical Epidemiology and Trials Organization Unit, Fondazione IRCCS Istituto Nazionale dei Tumori., Department of Pathology and Laboratory Medicine, Fondazione IRCCS Istituto Nazionale dei Tumori., Department of Radiology, Fondazione IRCCS Istituto Nazionale dei Tumori., Department of Surgery Urology Unit, Fondazione IRCCS Istituto Nazionale dei Tumori., Pharmacy Unit, Fondazione IRCCS Istituto Nazionale dei Tumori, Milano, Italy.