Generex Biotechnology announces $444,000 phase I NIH SBIR award for melanoma peptide vaccine

17-Sep-2003

Generex Biotechnology Corporation announced that the National Cancer Institute has awarded a Small Business Innovative Research (SBIR) grant to support development of a novel vaccine for T- helper cell-stimulating peptide vaccines to treat malignant melanoma. The research will be carried out by Antigen Express, Generex's subsidiary focused on the development of novel immunomedicines.

The grant supports the design, synthesis and testing of potent Ii-Key/melanoma peptides for possible subsequent clinical studies. The laboratory experiments will be performed in test tubes with lymphocytes from melanoma patients. The most reactive Ii-Key/melanoma peptides from gp100 and tyrosinase will be tested in combination with corresponding cytotoxic T-cell stimulating peptides, which have been used previously in the clinic.

The goal is to induce a potent antigen-specific T-helper cell response in vivo using the Ii-Key/MHC hybrid peptides, in order to stimulate a more robust cytotoxic immune response against melanoma. Some of the pre-clinical studies needed before initiating clinical trials are also funded.

The Ii-Key/MHC Class II vaccine hybrids are a novel cassette structure joining a biologically active segment of the immunoregulatory Ii protein through a polymethylene linker to an HLA-DR-presented epitope. In vitro such Ii-Key/MHC Class II hybrids boost the potency of the cassette-inserted MHC Class II epitope 500 to 2000 times that of the epitope-only peptide.

The minimal potent structure of the Ii-Key peptide was defined with 160 homologs. It interacts with an allosteric site just outside the antigenic peptide-binding site on MHC class II molecules in a manner to loosen antigenic peptide binding in that site. Previously bound peptides can be spilled and synthetic antigenic peptides inserted.

Ii-Key/antigenic epitope hybrids might represent a quantum advance in peptide vaccination using MHC Class II epitopes, substantially boosting peptide and DNA vaccine strategies for cancer and infectious disease. Likewise, Th1 or Th2 immunodeviating effects of Ii-Key hybrids might be useful in controlling allergy and autoimmune disease.

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