Ripretinib is currently in clinical development for the treatment of gastrointestinal stromal tumours (GIST). GIST is a rare type of cancer that commonly develops in the gastrointestinal tract. The cause of GIST is unknown, but most cases are associated with a certain gene mutation that produces abnormal enzymes. GIST are very aggressive, can spread quickly to other parts of the body (metastatic) and are not easily removed surgically (unresectable). There are currently no approved therapies for patients with GIST who are resistant to imatinib. Ripretinib is a drug orally administered to stop the abnormal and overactive enzymes in GIST cells from working, including forms that cannot be blocked by other medicines. Stopping these enzymes is expected to slow down the growth of the tumours and reduce symptoms of the disease. If licensed, ripretinib will offer a second-line treatment option for patients with unresectable or metastatic GIST who were resistant to imatinib.