FDA Approves Ayvakit (Avapritinib) for GIST

The US Food and Drug Administration (FDA) has approved Ayvakit (avapritinib) to treat people with advanced cases of gastrointestinal stromal tumor (GIST) that have a certain genetic mutation. GIST is a type of cancer that grows in the gastrointestinal tract, most often in the stomach or small intestine. The new drug approval is for GISTs with certain mutations in the PDGFRA gene.

Only about 5% to 10% of GISTs have a PDGFRA mutation. These tumors usually do not respond well to therapies already on the market. Ayvakit is a type of targeted therapy called a tyrosine kinase inhibitor. It works by blocking certain proteins (including PDGFRA) that help the cancer cells divide and grow.

The FDA based its approval on a clinical trial of 43 people with GIST that had a change in the PDGFRA gene known as an exon 18 mutation. The trial measured response rate, which is how many participants’ tumors shrank by at least a certain amount after taking Ayvakit. The overall response rate was 84%, with 7% having a complete response (no sign of any remaining tumor) and 77% having a partial response. For a subgroup of patients who had a specific PDGFRA D842V mutation, the complete response rate was 8% and the partial response rate was 82%.

Ayvakit was evaluated by the FDA using breakthrough therapy and fast track designations – programs designed to speed up the availability of drugs to treat serious diseases. It was also granted orphan drug designation, which provides financial incentives to encourage the development of drugs for rare diseases.

Ayvakit is a pill taken once a day. Side effects can include swelling, nausea, vomiting, decreased appetite, diarrhea, abdominal pain, constipation, fatigue, thinking problems, changes in hair color, excess tears, rash, and dizziness.

Patients should stop taking Ayvakit or take a lower dose if it causes bleeding inside the skull. Ayvakit should be stopped temporarily or permanently if it causes problems in the central nervous system including thinking problems, dizziness, sleep disorders, mood disorders, speech disorders, and hallucinations. Pregnant women are warned that Ayvakit may harm a fetus or newborn baby. Men and women of reproductive age should use birth control while taking Ayvakit.

Ayvakit is marketed by Blueprint Medicines Corporation.