The immune system is very complex and one of the least understood areas of our biology, which is reflected in the presently poor knowledge of the causes of autoimmune disorders and lack of effective treatment options. There is a lot of work taking place on manipulating the immune system to attack cancer, however, and this and other work on immunity will in the years ahead establish the understanding that is presently lacking. This research is an example of the type, and may ultimately turn out to be more valuable for what it reveals about the immune system rather than its use in cancer treatment:
A class of drug currently being used to treat leukaemia has the unexpected side-effect of boosting immune responses against many different cancers. The drugs, called p110δ inhibitors, have shown such remarkable efficacy against certain leukaemias in recent clinical trials that patients on the placebo were switched to the real drug. Until now, however, they have not been tested in other types of cancer.
The team showed that inhibiting p110δ in mice significantly increased cancer survival rates across a broad range of tumour types, both solid and haematological cancers. For example, mice in which p110δ was blocked survived breast cancer for almost twice as long as mice with active p110δ. Their cancers also spread significantly less, with far fewer and smaller tumours developing.
"When we first introduced tumours in p110δ-deficient mice, we expected them to grow faster because p110δ is important for the immune system. Instead, some tumours started shrinking. When we investigated this unexpected effect, we found that p110δ is especially important in so-called regulatory T cells which are suppressive immune cells that the tumours engage to protect themselves against immune attack. Our work shows that p110δ inhibitors can shift the balance from the cancer becoming immune to our body's defences towards the body becoming immune to the cancer, by disabling regulatory T cells. This provides a rationale for using these drugs against both solid and blood cancers, possibly alongside cancer vaccines, cell therapies and other treatments that further promote tumour-specific immune responses."