Background: In a Phase II trial, surgical adjuvant active specific immunotherapy using a live vaccinia virus-augmented allogeneic polyvalent melanoma cell lysate, vaccinia melanoma oncolysate (VMO), produced a significant disease free interval (DFI) in patients with International Union Against Cancer Stage II melanoma with positive lymph nodes. Therefore, a Phase III randomized prospective, double-blind, multiinstitutional, surgical adjuvant VMO trial was performed to determine the efficacy of VMO to increase the DFI and the overall survival in this group of patients with Stage II disease.
Methods: Two hundred and fifty patients with Stage II melanoma were divided into two postsurgical groups. One group received VMO (total protein equals 2 mg/ml) and the other received the placebo of live vaccinia vaccine virus (V) (10(5.4) TCID50/ml), an adjuvant component of the VMO. Patients initially received these biologics once a week for 13 weeks and then once every 2 weeks for an additional 39 weeks or until recurrence. All surviving patients have been followed for at least 30 months.
Results: Statistical analysis of survival data (n = 217) for this first interim analysis shows that there is no statistically significant (P = 0.99) increase in DFI of patients treated with VMO (n = 104) when compared with V (n = 113). The median DFI is 38.0 months for patients treated with VMO and 37.0 months for patients treated with V. At 2- and 4-year intervals, 70 and 38%, respectively, of patients treated with VMO vs. 66 and 36%, respectively, of patients treated with V were free of melanoma. The median overall survival is not available because the patients treated with VMO have not yet reached the 50% mark and the median overall survival is 45.0 months for patients treated with V. At 2- and 4-year intervals, 70 and 38%, respectively, of VMO-treated patients survived when compared with 66 and 36%, respectively, of patients treated with V. Although the overall survival of patients treated with VMO is not statistically significant (P = 0.88) at this point, there is an increasing trend in the overall survival of patients treated with VMO; a 10% increase at the 4-year time point. Moreover, in the subset analysis, VMO-treated male patients (n = 63) showed a 17% improvement in survival at 4-year time point when compared with male patients treated with V (n = 67) (P = 0.19) at the same time point and male patients (n = 20) between the ages of 44 and 57 having 1-5 positive lymph nodes showed a 37% difference in overall survival at the 4-year time point when compared with those patients treated with V (n = 18) (P = 0.13) at the same time point.
Conclusion: In this first interim analysis, active specific immunotherapy with VMO vs. V showed no difference in the disease free interval or overall survival. Subset analyses likewise showed no significant differences in outcome but the data suggest a potential difference in immunoreactivity between male and female patients with melanoma that awaits further follow up and may merit further investigation.