M-Vax: an autologous, hapten-modified vaccine for human cancer.

A novel approach to active immunotherapy has been devised based on modification of autologous cancer cells with the hapten, dinitrophenyl (DNP). This technology is being developed by AVAX Technologies as a treatment for melanoma under the brand name, M-Vax(TM). The treatment program consists of multiple intradermal injections of DNP-modified autologous tumour cells mixed with Bacille Calmette-Guérin (BCG). DNP-vaccine administration to patients with metastatic melanoma induces a unique reaction - the development of inflammation in metastatic masses. The inflammation is mediated by IFN-gamma-producing T-lymphocytes, some of which represent expansion of novel clones. Following DNP-vaccine treatment, almost all patients develop delayed-type hypersensitivity (DTH) to autologous, DNP-modified melanoma cells; approximately half also exhibit DTH to autologous, unmodified tumour cells. The toxicity of the vaccine is mild, consisting mainly of papules or pustules at the injection sites. Clinical trials have been conducted in two populations of melanoma patients: stage IV with measurable metastases and clinical stage III patients, rendered tumour-free by lymphadenectomy. In 83 patients with measurable metastases, there were 11 antitumour responses: two complete responses (CRs), four partial responses (PRs) and five mixed. Both CRs and two of four PRs occurred in patients with lung metastases. In 214 stage III patients the 5-year overall survival rate was 46% (one nodal site = 48%, in-transit metastases = 50%, two nodal sites = 36%). In both populations, the induction of DTH to unmodified autologous tumour cells was associated with significantly longer survival. This technology is applicable to other human cancers and clinical trials have been initiated with ovarian adenocarcinoma. There appear to be no insurmountable impediments to applying this approach to much larger numbers of patients or to developing it as a standard cancer treatment.