Phase II trial of pexa-vec (pexastimogene devacirepvec; JX-594), an oncolytic and immunotherapeutic vaccinia virus, in patients with metastatic, refractory renal cell carcinoma (RCC).

Abstract

671 Background: Pexa-Vec is a vaccinia virus engineered to express granulocyte-macrophage colony stimulating factor (GM-CSF), thereby stimulating anti-tumor immunity, direct oncolysis, and tumor vascular disruption. ( Nat Rev Cancer 2009). Pexa-Vec was shown to replicate in metastatic tumors following intratumoral (IT) or intravenous (IV) administration ( Lancet Oncol 2008; Nature 2011). Methods: RCC patients failing at least 1 prior VEGF/R-targeted therapy received five weekly IV Pexa-Vec infusions. Starting at Week 6, patients with disease control or otherwise clinically benefitting from treatment could continue to receive IV infusions every 3 weeks. The primary study objective was radiographic response based on modified Response Evaluation Criteria (RECIST) 1.0. Secondary objectives included disease control rate, progression free survival and safety. Results: All seventeen patients enrolled received the initial 5 weekly Pexa-Vec infusions. Twelve patients received at least one additional infusion (median Pexa-Vec infusions = 8; range 5-12). The treatment regimen was well-tolerated. Transient influenza-like illness (100%), asthenia (47%), anemia (29%) and nausea (29%) were the most common adverse events. All patients were evaluable radiographically at Week 6. The RECIST disease control rate was 76% at Week 6 including 1 complete response. Conclusions: Pexa-Vec was well-tolerated and associated with one complete RECIST response and 76% disease control at Week 6 in patients with advanced RCC. Further trials of Pexa-Vec in RCC patients are warranted.