Increased survival of patients treated with a vaccinia melanoma oncolysate vaccine - Second interim analysis of data from a phase III, multi-institutional trial

Objective The efficacy of vaccinia melanoma oncolysate (VMO) vaccine to increase overall survival and disease-free survival of patients with surgically resected International Union Against Cancer (UICC) stage II melanoma was studied in a phase III, randomized, multi-institutional trial, Summary Background Data Phase I and II trials with VMO showed minimal toxicity and clinical efficacy in patients with melanoma. In a recently completed phase Ill VMO trial, the first interim analysis performed in April 1994 showed an increasing trend in the survival of patients treated with VMO. The second interim analysis was performed in April 1995. Methods Patients with surgically resected stage II (UICC) melanoma were treated with VMO (N = 104) or placebo vaccinia vaccine virus (V) (N = 113) once a week for 13 weeks and then once every 2 weeks for a total of 12 months. Patients' clinical data were collected as of May 1995 and analyzed for survival. Results In this second interim analysis, the mean follow-up time is 42.28 months. No survival difference was observed between VMO and V treatments. However, in a retrospective subset analysis, a subset or males between the ages of 44 and 57 years and having one to five positive nodes (at 2-, 3-, and 5-year intervals, 13.6%, 15.9%, and 20.3% difference in survival in favor of VMO [N = 20] when compared to V [N = 18] [p = 0.037]) and another subset of patients with clinical stage I (at 3- and 5-year intervals, 30% and 7% difference in survival in favor of VMO [N = 20] when compared to V [N = 23], [p = 0.051]) showed significant survival advantage with VMO. Conclusions Although VMO vaccine therapy in surgical adjuvant setting did not produce a significant survival benefit to all patients with melanoma, patients from the above two subsets had significant survival benefit.