Traditional cancer therapies –such as chemotherapy and radiation –have been mostly ineffective in treating the disease. Surgery remains the primary treatment used in the management of GIST. However, some GISTs cannot be surgically removed because they are too large or because they have already spread to another part of the body. Even with surgery, parts of the original GIST may remain or the tumor may recur (return) in another part of the body. In addition, GISTs often recur even when completely removed.

Tyrosine kinase inhibitors (TKIs) are medications that can be taken orally. Some have been approved by the Federal Food and Drug Administration to treat KIT+ GISTs that cannot be surgically removed and/or that have become metastatic (spread to other parts of the body). Some have also been approved for use after surgery to prevent GIST tumors from recurring. These agents target the cause of almost all GISTs –the abnormal KIT protein. TKIs work in GIST by blocking, or turning off, the signal from the KIT protein. This may make the GIST cells stop growing. [Note: GISTs that are not KIT+ may also be treated with a TKI, although the choice of drug may be different.]