The use of the immune system to target cancer has been a therapeutic goal for over a century. The advantage of immunotherapy is the possibility of targeting cancer throughout the body in a non-toxic manner, thus allowing destruction of metastasis, and induction of immunological memory to protect from relapse. Unfortunately with exception of the recent FDA approval of Dendreon’s prostate cancer vaccine on April 29th, 2010 all other cancer vaccine Phase III clinical trials have failed. The company ImmunoCellular Therapeutics believes that one of the reasons for poor efficacy of previous trials revolves around the fact that they were targeting the wrong
type of tumor cell.
It is known that tumors are comprised of rapidly multiplying cells and "sleeping" cells. The cells that are dormant appear to act as stem cells in that they are capable of starting a brand new tumor when transplanted to mice. To date, cancer vaccines have been designed to kill rapidly multiplying tumor cells but not the dormant stem cells. ImmunoCellular Therapeutics has been collaborating with the Torrey Pines Institute to identify molecules found on tumor stem cells that can be used to generate vaccines. Today the company announced some progress in its quest.
The company claims to have identified several peptides which can generate T-cells capable of killing cells that express the protein CD133. This protein according to the press release, is found in high abundance on cancer stem cells. What is interesting is that this protein is also found on healthy, non-cancerous, stem cells such as circulating endothelial progenitor cells. Therefore it will be interesting to see if the vaccines that are being developed will have adverse effects. Theoretically the cancer stem cells should be more difficult to target with a vaccine as compared to non-malignant stem cells due to the fact that cancer stem cells generally secrete immune suppressive factors that protect them from the body’s attack.
Torrey Pines Institute and Immunocellular Therapeutics have expanded their existing research agreement to conduct additional studies to support an Investigational New Drug Application (IND) filing. This is an application to the FDA to ask for permission to perform clinical trials in humans.
Additionally, the press release stated that ImmunoCellular Therapeutics and the Torrey Pines Institute will work on research programs with other proteins found on cancer stem cells such as Numb and Notch.
Dr. Manish Singh, President and Chief Executive Officer of ImmunoCellular Therapeutics stated "We are excited by the discoveries to date that could prove
efficacious in treating cancer," he continued, "We look forward to expanding our relationship with the Torrey Pines Institute."