GIST occurs when cancerous cells build up inside the gastrointestinal tract. There are between 3,000 to 6,000 new cases of GIST every year in the U.S, according to data published by the National Cancer Institute.
As a multi-kinase inhibitor, Stivarga prevents cancer growth by blocking the key enzymes that make the cancer spread. The drug is for patients who no longer respond to other approved forms of treatment, such as Gleevec or Sutent (both made by Pfizer), or whose GIST cannot be removed surgically.
The director of the Office of Hematology and Oncology Products in the FDA's Center for Drug Evaluation and Research, Richard Pazdur M.D., said:
"Stivarga is the third drug approved by the FDA to treat gastrointestinal stromal tumors. It provides an important new treatment option for patients with GIST in which other approved drugs are no longer effective."
Because there are no other satisfactory forms of therapy - when patients don't respond to current treatment options - the drug underwent an expedited six-month review as part of the FDA's priority review program. As the medication is used to treat a rare disease it was also granted orphan product designation.
A total of 199 patients were included in a study that evaluated the effectiveness of the drug. All of the patients suffered from GIST that was surgically impossible to remove, in addition, they weren't responding to treatment with Gleevec and Sutent.
The patients were randomly put on either a Stivarga treatment course, or placebo. They all received additional treatments to alleviate any side effects. Patients discontinued treatment when the cancer progressed, or the side effects became too severe.
Stivarga was found to delay tumor growth for an additional 3.9 months compared to placebo. Patients who took the placebo had the option of switching to Stivarga if their cancer progressed.
Some common side effects of the drug include:
- High blood pressure
- Weakness and fatigue
- Stomach pain
- Weight loss
- Loss of appetite
- Liver damage
- Blistering and peeling of the skin
- Extremely high blood pressure
- Heart attack