Phase II clinical trial with a second generation, GM-CSF encoding, oncolytic herpesvirus in unresectable metastatic melanoma
9035 Background: OncoVEXGM-CSF is a an oncolytic HSV, encoding GM-CSF . We recently completed a phase II trial involving 50 advanced melanoma patients (stage IIIc and IV) with at least one injection accessible lesion, including by ultrasound. Methods: Patients received a single IT injection of 106 pfu/ml apportioned between 10 or less injectable tumors, followed 3 wks later by 24 or less sequential injections of 108 pfu/ml every 2 wks until clinically significant disease progression, or overall or injectable lesion complete response. Response (RECIST modified to allow progression before response and biopsy of residual masses) and survival were monitored. Results: All 50 pts have been enrolled and are evaluable (Stage IIIc, n=10; IV M1a, n=16; IV M1b, n=4; IV M1c, n=20). A median of 6 injections were administered. Adverse effects were limited and generally involved transient flu-like symptoms. Both injected and uninjected regional and distant disease demonstrated response including clearly documented responses at uninjected visceral sites. The overall response rate was 26% (8 CR, 5 PR); 10 responses have been maintained for >6 months and 2 are ongoing at <6months, the longest currently being at 35 months from first dose. 93% of patients (14 of 15) with PR, CR or surgical CR remain alive. Ten additional patients had SD for >3 months. Kaplan Meier one year survival is 61% overall, 58% stage IV only, 48% for Stage IV M1c. The median OS is 16+ months. Conclusions: The 1-year survival and durable objective response rate are encouraging. Responses of distant and visceral disease provide further compelling evidence of systemic effectiveness. This, combined with a limited toxicity profile, suggests OncoVEXGM-CSF is a promising treatment for metastatic melanoma. A phase III clinical trial is planned. [Table: see text]