A phase II trial of vaccination with autologous, tumor-derived heat-shock protein peptide complexes Gp96, in combination with GM-CSF and interferon-alpha in metastatic melanoma patients.

The aim of this study was to determine the immunogenicity and antitumor activity of autologous, tumor-derived heat shock protein gp96-peptide complex vaccine (HSPPC-96; Oncophage given with GM-CSF and IFN-alpha in pre-treated metastatic (AJCC stage IV) melanoma patients. Patients underwent surgical resection of metastatic lesions for HSPPC-96 production. HSPPC-96 was administered subcutaneously (s.c.) in four weekly intervals (first cycle). Patients with more available vaccine and absence of progressive disease received four additional injections in 2-week intervals (second cycle) or more. GM-CSF was given s.c. at the same site at days -1, 0 and +1, while IFN-alpha (3 MU) was administered s.c. at a different site at days +4 and +6. Antigen-specific anti-melanoma T and NK lymphocyte response was assessed by enzyme-linked immunospot assay on peripheral blood mononuclear cells obtained before and after vaccination. Thirty-eight patients were enrolled, 20 received at least four injections (one cycle) of HSPPC-96 and were considered assessable. Toxicity was mild and most treatment-related adverse events were local erythema and induration at the injection site. Patients receiving at least four injections of HSPPC-96 were considered evaluable for clinical response: of the 18 patients with measurable disease post surgery, 11 showed stable disease (SD). The ELISPOT assay revealed an increased class I HLA-restricted T and NK cell-mediated post-vaccination response in 5 out of 17 and 12 out of the 18 patients tested, respectively. Four of the five class I HLA-restricted T cell responses fall in the group of SD patients. Vaccination with autologous HSPPC-96 together with GM-CSF and IFN-alpha is feasible and accompanied by mild local and systemic toxicity. Both tumor-specific T cell-mediated and NK cell responses were generated in a proportion of patients. Clinical activity was limited to SD. However, both immunological and clinical responses were not improved as compared with those recorded in a previous study investigating HSPPC-96 monotherapy.