Flt3 ligand performs poorly as adjuvant for prostate cancer vaccine.

2003 MAR 19 - (NewsRx.com & NewsRx.net) -- by Maria G. Essig, MS, ELS, senior medical writer - The number of dendritic cells stimulated by an MHC class I peptide vaccine consisting of the E75 HLA-A2 epitope from HER-2/neu were increased when the flt3 ligand was added as an adjuvant, but no proliferation of peripheral skin antigen-presenting cells occurred, according to a report in the Journal of Clinical Immunology.

Douglas G. McNeel and collaborators at the University of Wisconsin Comprehensive Cancer Center and the University of Washington performed a pilot study to determine the safety and effectiveness of the flt3 ligand as a systemic adjuvant for the HER-2/neu E75 HLA-A2 epitope vaccine.

The investigators randomly assigned 20 patients with advanced prostate cancer to receive either 20 microgram/kg of the flt3 ligand subcutaneously each day for 14 days on a 28-day cycle, monthly for 4 months; the same flt3 dose schedule with the addition of the E75 peptide vaccine on the seventh day of each flt3 ligand cycle; the same flt3 dose schedule with the addition of the E75 peptide vaccine on the fourteenth day of each flt3 ligand cycle; or the E75 peptide coadministered with granulocyte-macrophage colony-stimulating factor (GM-CSF) once every 28 days.

Although the flt3 ligand increased the number of dendritic cells found in peripheral blood samples, the numbers of antigen-presenting cells within the dermis did not rise. Only one patient experienced a significant increase in peptide-specific T lymphocyte response. However, delayed-type hypersensitivity responses occurred in the patients who received the GM-CSF and early in the study for patients receiving ftl3.

Three patients experienced adverse reactions, including one with a grade 3 skin reaction and two who developed grade 2 autoimmune hypothyroidism. However, both patients who ...