Hybrid cell vaccination in metastatic melanoma: clinical and immunologic results of a phase I/II study

Hybrid cell vaccination with cell fusion products (CFPs) of autologous tumor cells and mature allogenic MHC II bearing dendritic cells has been described to induce cytotoxic T lymphocyte (CTL)-mediated immune responses. The aim of this study was to assess safety, antitumor activity, and immune responses of a CFP-vaccine in patients with disseminated malignant melanoma. In a phase I/II study, we treated 11 patients by monthly intracutaneous or subcutaneous application of a CFP vaccine generated by electrofusion of autologous melanoma cells with mature allogenic dendritic cells. In addition, patients received subcutaneous low-dose interleukin-2 injections for 6 days after each vaccination. No serious adverse effects were observed. Ten patients showed progressive disease and one patient had a short-lasting stable disease. None of the patients developed a positive delayed-type hypersensitivity reaction against irradiated autologous melanoma cells. In 2 patients, who were monitored in more detail, we found no evidence of induction of a specific antimelanoma T-cell response by analyzing the proliferation, cytokine secretion, and cytotoxicity of their T cells toward autologous melanoma cells. No unequivocal beneficial effects of the used CFP vaccine could be demonstrated.