Corynebacterium parvum versus bacille calmette-guérin adjuvant immunotherapy of stage II malignant melanoma

Two separate studies have been reported comparing Corynebacterium parvum and bacille Calmette-Guérin (BCG) as adjuvant immunotherapy for stage II melanoma patients (The Milton S. Hershey Medical Center, 48 patients; Southeastern Cancer Study Group [SECSG], 162 patients). As the criteria for patient selection and drugs used were similar, we have pooled the data to analyze the effects of these two treatments. Both studies used BCG (Tice, Chicago, IL) 3 x 10⁸ live organisms per treatment by Tine technique and C parvum (Burroughs-Wellcome, Triangle Park, NC) subcutaneous at a dose of 4 mg/m² (SECSG) or 5 μg/m² (Hershey) per treatment. The only difference in these studies was the frequency of immunization, with patients in Hershey receiving 22 doses and the SECSG patients receiving 55 doses during the 2-year period of treatment. Kaplan-Meier life-table analysis for the 210 patients shows a prolonged disease-free interval for patients treated with C parvum (P = .02, two-sided Mantel procedure). In similar fashion, patients treated with C parvum had an improved survival rate (from all causes) when compared with BCG-treated patients (P = .012). An analysis of the results for the 170 patients for which the number of positive nodes was available was performed using Cox's model, with nodes as a stratification variable and with covariates of place, treatment, age, and sex. In this analysis, an observed benefit for C parvum on the disease-free interval had a P value of .37 while the benefit of C parvum on the survival times (from all causes) had a P value of .04. When the same analysis was performed using only patients aged younger than 60 years, the observed benefit of C parvum on disease-free interval had a P value of .08 and the benefit of C parvum on survival times (from all causes) had a P value of .008.