Although non-specific cytotoxic drugs still have their place in the treatment of cancers, the ability to tailor therapy to the precise genetic make-up of a malignancy has greatly improved the prospects of many patients. Precision medicine strategies range from drugs that target specific antigens that are overexpressed on the surface of cancer cells to vaccination programmes that prime the body’s own immune system to fight back.
The number of cancer vaccine products already on the market is limited. The first to be approved in the US, back in 2010, was sipleucel-T (Provenge) from Dendreon, now owned by Valeant. The vaccine is based on autologous dendritic cells, harvested from the patient’s blood via leukapheresis. These are then cultured with the protein PAP-GM-CSF, of which the granulocyte-macrophage colony stimulating factor component stimulates the immune system, and enhances the presentation of the antigens.
The only other cancer vaccine to be given FDA approval, talimogene laherparepvec (Imlygic), originally developed by BioVex and acquired by Amgen, was ratified in late 2015. This is an oncolytic viral therapy, and is a genetically engineered form of the cold sore virus, herpes simplex-1. It has been attenuated, its selectivity to cancer cells was increased, and it was also engineered to secrete GM-CSF. It is licensed for the treatment of melanoma, and is directly injected into the tumours; it also has systemic effects.
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