This article, published in Nature just before Christmas, gives a good overview of the use of combinations of immunotherapy drugs to fight cancer.
Immunotherapies trigger the immune system causing a self-sustaining attack against cancer cells by immune cells known as T cells, producing long-term clinical benefits, and, in some cases, a cure. Around 2,000 immunotherapy drugs are currently in development, but some people will respond better to the drugs than do others, and many don’t respond to them at all. Moreover, tumours can become resistant to immunotherapy drugs over time.
These limitations have resulted in researchers using several drugs in combination, and data gathered by the Cancer Research Institute in the USA show that 403 combination trials opened worldwide in the first six months of 2017, and more than 1,100 trials are in progress. By combining immunotherapy drugs, or pairing them with other types of cancer treatment such as chemotherapy or radiotherapy, researchers hope to enhance and broaden the benefits.
However, there are challenges to using combinations: Immunotherapies send cancer-cell-killing T cells into overdrive, and may trigger dangerous autoimmune reactions that combination treatments can exacerbate. And the cost of the drugs is much greater than that of conventional treatments for cancer.