Phase I/II trial of melanoma patient-specific vaccine of proliferating autologous tumor cells, dendritic cells, and GM-CSF: planned interim analysis.

Aim: The aim of this study was to investigate the feasibility, safety, and clinical efficacy of patient-specific dendritic cell vaccines in patients with metastatic melanoma. A planned interim analysis was conducted on the first 20 patients.

Methods: Tumor cell lines were established from metastatic tumor, expanded to 200 million cells, and then incubated with interferon-gamma for patients who were candidates for therapy. Cells were irradiated and cryopreserved. Patients underwent leukapheresis to obtain mononuclear cells that were cultured in the presence of IL-4 and GM-CSF to produce dendritic cells, which were incubated with cryopreserved, irradiated tumor cells, and then stored in aliquots of about 20 million cells for subcutaneous (s.c.) injections with GM-CSF once a week for 3 weeks, then once a month for 5 months.

Results: The first 20 eligible patients included 10 men and 10 women, with a median age of 48 years (range, 16-79 years). Three (3) patients had brain metastases, and 13 patients had experienced disease progression after biochemotherapy. At the time of vaccine treatment, 6 patients had evaluable metastatic disease, while 14 patients lacked measurable disease. Vaccine therapy was well tolerated, except for what appeared to be GM-CSF-related allergic reactions in 2 patients. Delayed-type hypersensitivity (DTH) tests to irradiated tumor cells were positive in 0 of 20 patients tested at baseline, but converted to positive in 8 patients (40%). At a median follow-up of 13.8 months, there is a 95% overall survival and a 48% progression-free survival. Four (4) patients have already survived more than 3.0 years since starting the vaccine.

Conclusion: Based on tolerability, rate of tumor DTH conversion, and encouraging survival, the trial will continue accrual to at least 19 patients with measurable disease and 40 patients who lack measurable disease at the time of treatment.