Active immunotherapy as an adjunct to chemotherapy in the treatment of disseminated malignant melanoma: a pilot study

Abstract

In patients with disseminated malignant melanoma an optimal method of immunization with irradiated tumour cells was developed by reference to an in vitro assay for circulating specific serum inhibitors of cell mediated cytotoxicity. This immunization protocol consisted of the intradermal inoculation of 2 times 10(7) irradiated allogeneic melanoma cells admixed with 50 mug of percutaneous BCG. This method of immunization induced a significant but transient fall in the specific inhibitory effects of the sera on tumour directed cytotoxic activity of the patients' lymphocytes. In a pilot group of 30 patients with disseminated malignant melanoma being treated with chemotherapy (DTIC and vincristine) the immunotherapy was given midway between courses of the cytotoxic drugs. There was a correlation between the effects on circulating inhibitor and clinical outcome. The number of objective regressions occurring in this small pilot group was surprisingly high (17/30) and these clinical effects, although obtained in a series without concurrent controls, are presented for discussion. We suggest that the approach illustrated by this study, employing in vitro assays of tumour directed immune responses, may provide a suitable rational basis for the use of active immunotherapy as an adjunct to chemotherapy in the treatment of malignant disease.