Interim Results of a Phase II Multicenter Clinical Trial Evaluating the Activity of a Therapeutic Allogeneic Melanoma Vaccine (Theraccine) in the Treatment of Disseminated Malignant Melanoma

Abstract

A total of 139 patients with disseminated malignant melanoma were enrolled in an uncontrolled Phase II trial evaluating the activity of Melacine®, allogeneic vaccine incorporating Detox™, immunologic adjuvant. Nineteen patients, including 18 with progressive disease, dropped out of the study prior to receiving one full vaccination course of five injections over 6 weeks. Disease presentation among study participants included skin or lymph nodes (34%), pulmonary (24%), visceral (34%), and no evidence of disease (NED) (7%). One documented metastatic site was seen in 41%, two sites in 24%, and three or more sites in 27% of the patients studied. Objective clinical response rates for evaluable patients were CR 3%, PR 5%, minor response 4%, stable 23%, and progressive disease 65%. Median survival from time of diagnosis for patients treated with Melacine® is presently estimated at 23 months (45/139 patients censored). Median date from diagnosis of metastatic disease to study entry was 3 months. Side effects were generally mild to moderate with pain at injection site (37%), granulomas (13%), erythema (6%), and flu‐like symptoms (14–29%) predominating. Precursor antimelanoma cytotoxic T cell (pre‐CTL) titers, in comparison with prestudy evaluations, clearly increased in 42% of the patients evaluated. Significantly extended survival characteristics were observed among patients who displayed an expansion of a population of CD57, CD8 co‐positive lymphocytes during therapy in comparison with those patients not displaying this peripheral blood lymphocyte (PBL) population expansion (34 mo vs. 12 mo, respectively, p = 0.04) and among those patients displaying disease stabilization or better as a clinical response (p = 0.001). At this interim analysis, increased pre‐CTL on‐study titers did not predict a statistically significant survival advantage.