EDMONTON, Alberta, Canada The MUC-1 peptide, found on more than 90 percent of solid tumors, is an inviting target for cancer vaccine biotech companies against which to try to raise an immunological response in order for the cancer cell to be destroyed by the immune system.
This strategy has brought together both Biomira Inc. and U.K.-based Axis Genetics plc in a research collaboration that will assess the further potential of therapeutic cancer vaccines against MUC-1. Each company has developed a vaccine targeting the MUC-1 peptide. Since the two vaccines induce different, potentially complementary types of immune responses, Biomira which already has a major research effort in cancer vaccines will evaluate Axis¿ vaccine in preclinical studies.
Biomira¿s liposomal MUC-1 peptide vaccine, BLP25, is currently being tested in a Phase I safety and dose comparison trial in patients with non-small-cell lung cancer. In animal studies, BLP25 has been shown to induce an anti-MUC-1 T-cell immune response and provide potent protection against tumor challenge.
Axis Genetics will supply the product using its proprietary chimeric plant virus particle (CVP) technology, Epicoat, which produces CVPs presenting MUC-1-derived peptides on the plant virus surface. The plant virus used is cowpea mosaic virus, whose particles are made up of two proteins: L (large) and S (small) coat proteins. A detailed study of their protein structure and topology has revealed a site within the S coat protein of each virus particle capable of presenting and displaying 60 copies of a foreign peptide.
The CVPs are relatively easy to manufacture. Leaf material containing large quantities of the modified virus is harvested 14 to 21 days after inoculation. The CVPs are then isolated by centrifugation and selective precipitation of homogenized plant material. Peptides up to 38 amino acids in size have successfully been incorporated into CVPs, the company said. The particles can be delivered by injection or nasally, to stimulate mucosal immune responses.
Michael Longenecker, Biomira¿s senior vice president of research, sees the Axis technology as a possible second-generation product to BLP25. For this reason, Biomira has acquired the rights to MUC-1 peptide vaccines in all major jurisdictions.
Axis has another North American alliance with the Boyce Thompson Institute for Plant Research, in Ithaca, N.Y., to develop edible plant vaccines for the prevention of hepatitis B, enterotoxigenic E. coli travelers¿ diarrhea and Norwalk virus infections.