Active Specific Intranodal Immunotherapy of Recombinant Vaccinia Virus in Locally Advanced to Metastatic Melanoma

The investigators have conducted a phase I/II clinical trial based on the intradermal administration to stage III/IV melanoma patients of a recombinant vaccinia virus encoding tumor associated antigens and costimulatory epitopes for the priming of immune responses, followed by boosts with corresponding synthetic peptides (Zajac P et al in Human Gene Ther 2003). Specific cytotoxic T cells could be induced in a majority of patients following priming, but sustained responsiveness could not be maintained by peptide boosting on a long term basis. Emerging evidence supports the notion that expansion of specific T cells requires trafficking of antigen presenting cells loaded with specific determinants to lymphatic nodes, as induced, among others, by pro-inflammatory stimuli. Therefore, we now adopt the intranodal injection of the immunogenic formulations. As for the former melanoma active specific immunotherapy trial, GM-CSF is used as a supporting cytokine. The epitopes considered are expressed, either all or some of them, in over 90% of the melanomas in Western countries; namely, we immunize with Mart-1/Melan-A epitope 27-35, Gp-100 epitope 280-288 and tyrosinase epitope 1-9. As a consequence, HLA-A2 positivity is mandatory for inclusion in the trial. The 2 costimulatory molecules expressed by cells infected with our replication-incompetent recombinant vaccinia virus are B7.1 (CD80) and B7.2 (CD86).