Active specific immunotherapy with vaccinia melanoma oncolysate.

Based on antitumor effects observed with vaccinia virus infected tumor cell lysate in animal models, adjuvant immunotherapeutic clinical trials were undertaken in patients with melanoma using vaccinia virus infected melanoma oncolysate (VMO). Preliminary clinical trials showed that the VMO is safe except minimal side effects such as mild fever, pain, and tenderness at the site of VMO injection, and mild lymphadenopathy. The effective dose of VMO was investigated in a following trial using 0.05 to 2.0 mg doses of VMO. Clinical responses and laboratory monitoring of melanoma-specific antibody responses decided the 2 mg dose of VMO is optimal for future trials. In all the clinical trials, patients showed moderate responses and their postimmune sera contained melanoma-specific antibodies. In a Phase II clinical trial completed August 1985 19 of 39 stage II patients had a disease-free mean survival time of 24.6 months, statistically significant compared with historical controls. Because of compelling evidence of significant clinical responses in patients treated with VMO adjuvant immunotherapy in the Phase II trial, a prospective randomized multi-institutional double-blind Phase III adjuvant VMO immunotherapeutic trial using adjuvant therapy of vaccinia virus alone as control, was recently initiated. Results of this trial are anxiously anticipated.