Biological therapies are treatments based on substances that are produced naturally in the body to destroy cancer cells.

Imatinib is a type of drug known as a tyrosine kinase inhibitor. It is sometimes used to treat gastrointestinal stromal tumours (GISTs). Imatinib works by blocking (inhibiting) signals within cancer cells and preventing a series of chemical reactions that make the cells grow and divide. The chemical it blocks is called tyrosine kinase. The effects of imatinib are very specific to GISTs. It is taken once a day as tablets.

Imatinib can cause side effects including feeling sick (nausea), vomiting, diarrhoea, a skin rash and puffiness, especially around the eyes. Some of the side effects can be reduced with other medicines.

Imatinib can sometimes control GISTs for several years.

Sunitinib is another tyrosine kinase inhibitor. It is sometimes used to treat GISTs that don’t respond to imatinib, or if the side effects of imatinib are too much. As well as blocking signals within the cancer cells and preventing a series of chemical reactions that make the cell grow and divide, it helps to prevent the tumour developing new blood vessels. Without blood vessels the tumour can’t get the nutrients it needs to survive.

Sunitinib has recently been licensed as a treatment for GISTs, but it may not be widely available. Your doctor can advise you if sunitinib is suitable for you.

Side effects of sunitinib include tiredness, diarrhoea, sore hands and feet, a sore mouth, taste changes and a loss of appetite.