Adjuvant immunotherapy in melanoma: a new approach

Patients with metastatic cutaneous melanoma to two or more regional lymph nodes have an extremely poor prognosis despite radical lymphadenectomy. In an attempt to improve the survival and to determine the safety of a new method of tumor specific adjuvant immunotherapy in such a high risk group of patients, nine patients were studied. Three to four weeks after regional lymphadenectomy, each of them received a single intradermal injection of Bacillus Calmette-Guérin. Three weeks later, they were immunized by allogenic melanoma cells obtained from live donors with distant metastases. Each patient received three vaccinations, each from a different donor (except in one), to avoid development of HLA response, but maintaining exposure to melanoma antigens. No cultured melanoma cells were used. Each vaccine consisted of mitomycin-C treated tumor cells mixed with purified protein derivative (PPD) of tuberculin given intradermally once per month for 3 months. The patients were then observed with no further treatment. Utilizing the leukocyte migration inhibition test, there was some in vitro evidence of tumor specific cell mediated response which seemed to disappear 1-2 months postimmunization. At 5 years, five of the nine patients (55%) were alive free of disease. No autoimmune diseases were detected in any of the immunized patients. A major hindering factor for such an approach was the limited availability of the allogenic melanoma cells.