8 April 2015
Exciting new research combines immunotherapy and personalised medicine approaches to target cancers more effectively.
Cancer immunotherapy seeks to harness the body’s natural immune responses to direct them more effectively against cancer cells. The body does have mechanisms to target ageing or aberrant cells for destruction, but cancer cells accumulate of a series of mutations that allow them to evade these processes and drive abnormal growth and behaviour.
Personalised cancer therapies seek to specifically target unique genetic features of the tumour cells that are not shared by the patient’s other cells in order to improve effectiveness (and reduce side-effects). The classic example is overexpression of the HER2 gene by some breast cancers, treated with Herceptin (trastuzumab), an antibody that specifically binds to HER-2 receptors and down-regulates their action.
Some surface tumour proteins, termed tumour antigens or neoantigens, are also important in eliciting natural anti-tumour immune responses and are unique to cancer cells. That is, they are not specified in the normal human genome, but arise from DNA mutations. Many hope that cancer immunotherapy that targets these neoantigens could be the key to really effective new cancer treatments, especially in providing long-term protection against cancer recurrence.
The new research reported in Science is a proof-of-concept human trial on three advanced melanoma patients who each received a personalised cancer vaccines targeted against specific tumour mutations and intended to induce immune responses, which they successfully did. The researchers used computational analysis to predict unique neoantigens from the tumour genomic information and select those likely to be the best targets for vaccine. The approach was said to be ‘more like a sniper than a bomb’ – using the neoantigens as flags to specifically target the cancer cells,
This was not really a treatment trial – the time taken to develop the personalised cancer vaccines, three months, was too long to be very effective against patients with severe, advanced forms of cancer, although in fact all three patients are reported to be stable or in remission since receiving the vaccines (along with other treatment) in 2013. However, the findings hold promise that it could become possible to develop timely and effective personalised vaccines against all sorts of cancers where immunotherapy has been shown to be effective.