A cancer vaccine is a treatment aimed at stimulating the patient’s immune system to act against cancer. Unlike other cancer therapies, such as chemotherapy and radiotherapy, cancer vaccines do not target or damage cancer cells directly. Instead, they assist the immune system in recognizing and generating an immune response against cancer cells. When it comes to developing cancer vaccines, many possible strategies exist, all of which are founded on presenting and provoking an immune response against one or more cancer-related antigens. An antigen is an element which can be recognized and attacked by the immune system. In the context of cancer vaccines, the term antigen is typically referred to different molecules presented on the external side of cancer cells.
Many attempts to develop cancer vaccines have been made throughout the years, none of which ever managed to reach approval stages. With several candidates currently in clinical trials, it is possible that in the near future there will be at least one commercially available cancer vaccine. Cell Genesys’ GVAX is a platform which has been used for developing some promising cancer vaccine candidates, which are undergoing multiple clinical trials.
The current low valuation of Cell Genesys (CEGE) implies that the market views GVAX as a one-trick pony. However, GVAX should be regarded as a multi-trick pony since it is a revolutionary platform for developing cancer vaccines for a substantial number of different cancers. Several months ago, I discussed the concept behind GVAX as a cancer vaccine in general, and about the prospects of GVAX for prostate cancer in particular. Nevertheless, there may be additional tricks under GVAX’s belt, apart from treating prostate cancer.
GVAX is composed of whole cancer cells genetically modified to secrete the immune stimulatory molecule, GM-CSF (granulocyte-macrophage colony-stimulating factor). GM-CSF has been proven to be a crucial growth and activation factor for a subgroup of immune cells called antigen-presenting cells (APCs), which play a vital role in the initiation of any systemic immune response. The GVAX cells are injected to cancer patients with the goal of manifesting an immune response through the stimulation of APCs. In order to prevent the GVAX cells from multiplying and creating new tumors once inside the body, they are lethally irradiated to prevent further cell division. Upon entering the blood circulation of a cancer patient, the GM-CSF secreted by the GVAX cells stimulates the patient’s immune system to recognize the GVAX cells as hostile and to attack them. Hopefully, since GVAX cells share many antigens with each patient’s cancer cells, this response will also be channeled against the patient’s cancer cells.
Predicting future success of drug candidates is very hard, let alone in an early-stage field such as cancer vaccines. With numerous cancer vaccines candidates currently being evaluated, it would be irresponsible to bet on just one approach or one platform, as there may be more than one winning strategy. Still, a thorough examination of the philosophy behind GVAX’s attributes and clinical data from several trials leads to the inevitable conclusion that GVAX has differentiated itself from the herd by presenting a truly innovative and elegant concept for cancer vaccines. Although being unique is by no means a guarantee for clinical success, there are several attributes, which make GVAX a very promising platform.