A randomized, controlled, open-label, phase 2 study of cemiplimab ± RP1 in patients with advanced cutaneous squamous cell carcinoma (CERPASS).

Abstract

TPS9593 Background: RP1 is an oncolytic virus (HSV-1) that expresses a fusogenic glycoprotein (GALV-GP R-) and granulocyte macrophage colony stimulating factor (GM-CSF). In preclinical studies, RP1 induced immunogenic tumor cell death and provided potent systemic anti-tumor activity, which is further improved by combining anti-PD-1 therapy. The prognosis for advanced and metastatic cutaneous squamous cell carcinoma (CSCC) remains poor for many patients despite the adoption of cemiplimab and pembrolizumab as a standard treatment. Preliminary results from IGNYTE, a phase I/II clinical study of RP1 in combination with nivolumab showed a high rate of deep and durable responses in patients (pts) with CSCC. This study is evaluating the efficacy and safety of cemiplimab ± RP1 versus cemiplimab alone in advanced CSCC. Methods: This global, multicenter, randomized phase 2 study is enrolling pts with metastatic or unresectable, locally advanced CSCC who are not candidates for/refuse surgery and/or radiation therapy. Key eligibility criteria include no prior treatment with anti-PD1/PD-L1 antibodies or oncolytic viruses. The clinical trial is enrolling approximately 180 pts from centers in the EU, Australia, Canada, and USA. Pts are randomized in a 2:1 ratio to receive combination therapy or monotherapy respectively. Pts receive 350 mg of cemiplimab intravenously (IV) Q3W for up to 108 weeks. In the RP1 + cemiplimab arm, RP1 is injected intratumorally at a starting RP1 dose of 1 × 106 plaque-forming units (PFU)/mL alone, followed by up to 7 doses of RP1 at 1 × 107 PFU/mL Q3W together with the same dose of cemiplimab. Pts in the combination arm may receive up to 8 additional RP1 doses if protocol specific criteria are met. No crossover is allowed. Pts are stratified by disease status (nodal or distant metastatic or locally advanced CSCC) and prior systemic therapy. Tumor assessments are performed every 9 weeks. The dual independent primary endpoints are overall response rate and complete response rate, both by a blinded independent review. Secondary endpoints include safety, progression-free survival, duration of response, and overall survival. Exploratory endpoints include quality of life, and immune biomarker analyses. This trial is currently enrolling pts. Clinical trial information: NCT04050436.