Background: This study was conducted to document the rate, duration, and type of objective response to active specific immunotherapy with a polyvalent melanoma cell vaccine (PMCV) for patients with in-transit melanoma metastases and to identify any acute or chronic toxic effects of PMCV treatment.
Methods: An analysis was conducted of all in-transit melanoma patients seen at the John Wayne Cancer Institute in Santa Monica, California, during the period 1985-1997 who were enrolled in prospective PMCV protocols in the absence of other therapies with possible antitumor activity (n = 54). Clinical response to PMCV was assessed by standard criteria. Survival curves were estimated by the Kaplan-Meier method. Toxicity was graded according to the Eastern Cooperative Oncology Group standard.
Results: PMCV produced a 17% (9 of 54 patients) objective response rate with a 13% rate (7 of 54 patients) of complete remission (CR). The median duration of CR was >22 months. Complete response lasting more than 1 year was observed in 4 patients (7.2%); 1 patient remained in remission over 9 years. Median survival was >53 months (i.e., not reached) for responders, 42 months for nonresponders, and 53 months overall. Salvage interventions allowed reinduction with PMCV in 23 of 25 patients, who subsequently remained clinically free of disease for a median of 14 months. Overall toxicity was mild, easily tolerable, and did not significantly change the quality of life. There were no toxic deaths.
Conclusions: PMCV can cause objective complete regression of measurable intransit metastatic melanoma with minimal toxicity, and may prolong patients' median survival.