Cancer vaccines on the horizon
5/15/2007 web-based article Dan Jones Nature Reviews (www.nature.com) With the approval of the first active immunotherapy pending, are we poised to enter the era of clinically effective cancer vaccines? On 29 March this year, the US FDA's Office of Cellular, Tissue and Gene Therapies Advisory Committee met to discuss the fate of Dendreon's leading cancer vaccine candidate Provenge (Sipuleucel-T). The Committee voted by 17–0 that Provenge was safe and 13–4 in favour of its efficacy in the treatment of metastatic, hormone-refractory prostate cancer. If things go in Dendreon's favour, Provenge might be approved as soon as mid-May. Provenge represents an extreme of 'personalized medicine'. Dendritic cells, which mop up antigens and present them to other cells of the immune system to stimulate a response, are taken from patients and then sent to one of Dendreon's repositories where they are treated with the prostate-specific antigen prostatic acid phosphatase (PAP), which is found in 95% of prostate cancers. Once returned to the patient, these activated dendritic cells should, in principle, activate T cells to attack and destroy cancer cells that are expressing PAP, leading to the eradication of the tumours. The cell-based approach taken by Dendreon is one of several options being pursued by cancer vaccine developers. Another popular approach is to use viral vectors to deliver genes encoding proteins that stimulate the immune system to attack cancer cells. Since the first such tumour antigens were identified in the early 1990s by Thierry Boon, a biologist at the Ludwig Institute for Cancer [...]