"This is the first time we have evaluated peptide-derived melanoma vaccine results from a multicenter cooperative group trial," said John Kirkwood, M.D., principal investigator of the study, professor of medicine at the University of Pittsburgh and director of the Melanoma Center at the University of Pittsburgh Cancer Institute (UPCI). "We have found evidence that the vaccine stimulates an immune response and that it is reasonable to evaluate the correlation between disease course and immune response for patients who receive the vaccine."
The phase II study evaluated a multiepitope CD8 T-cell vaccine comprised of three peptides derived from tumor-associated antigens of melanoma. The vaccine was evaluated alone, in combination with granulocyte macrophage-colony stimulating factor (GM-CSF), in combination with interferon and in combination with both GM-CSF and interferon.
The study included 120 patients with metastatic melanoma, many of whom had failed prior therapies. Patients received the vaccine by injection once every two weeks for 12 weeks. Immune response was assessed in 75 of the 120 patients, and 31% of those patients gave immune response as tested by the ELISPOT assay. Immune response to vaccination was associated with longer survival, but not with objective clinical tumor response or disease progression. Objective responses were noted in five patients treated with the triple peptide vaccine, including two complete and three partial responses, but these did not correlate with ELISPOT assays for immune response.
According to Dr. Kirkwood, the vaccine was fairly well tolerated by most patients with typical side effects that included vaccine site discomfort and expected toxicity to interferon and GM-CSF.
Malignant melanoma is one of the deadliest forms of skin cancer. An estimated 54,200 new cases of melanoma are expected in 2003 and 7,600 deaths are expected to occur.
The study includes more than 30 institutions across the country and is funded by a grant from the National Institutes of Health and awards to ECOG from the Schering Plough and Immunex Corporations.