The US Food and Drug Administration (FDA) expanded the approved use of Stivarga (regorafenib) to treat patients with advanced gastrointestinal stromal tumours (GIST) that cannot be surgically removed and no longer respond to other FDA-approved treatments for this disease.

GIST is a tumour in which cancerous cells form in the tissues of the gastrointestinal tract, part of the body’s digestive system. According to the National Cancer Institute, an estimated 3,300 to 6,000 new cases of GIST occur yearly in the United States, most often in older adults.

Stivarga, a multi-kinase inhibitor, blocks several enzymes that promote cancer growth. With this new approval, Stivarga is intended to be used in patients whose GIST cancer cannot be removed by surgery or has spread to other parts of the body (metastatic) and is no longer responding to Gleevec (imatinib) and Sutent (sunitinib), two other FDA-approved drugs to treat GIST.

Stivarga was approved in September 2012 to treat colorectal cancer. It is marketed by Bayer HealthCare Pharmaceuticals, based in Wayne, New Jersey. Gleevec is marketed by East Hanover, New Jersey-based Novartis, and Sutent is marketed by New York City-based Pfizer.

“Stivarga is the third drug approved by the FDA to treat gastrointestinal stromal tumours,” said Richard Pazdur, director of the Office of Hematology and Oncology Products in the FDA’s Center for Drug Evaluation and Research. “It provides an important new treatment option for patients with GIST in which other approved drugs are no longer effective.”

Stivarga was reviewed under the FDA’s priority review program, which provides an expedited six-month review for drugs that may provide safe and effective therapy when no satisfactory alternative therapy exists, or offer significant improvement compared to marketed products. The drug was also granted orphan product designation because it is intended to treat a rare disease.

The safety and effectiveness of Stivarga for this use were evaluated in a clinical study of 199 patients with GIST that could not be surgically removed and progressed after treatment with Gleevec or Sutent. Patients were randomly assigned to receive either Stivarga or a placebo. All patients also received optimal supportive care, which includes treatments to help manage side effects and symptoms of cancer.

Patients in the study took Stivarga or placebo until either the cancer progressed or the side effects became unacceptable. Results showed patients who took Stivarga had a delay in tumour growth (progression-free survival) that was, on average, 3.9 months later than patients who were given placebo. Patients who received the placebo were given the opportunity to switch to Stivarga when their cancer progressed.

The most common side effects reported in patients treated with Stivarga were weakness and fatigue, hand-foot syndrome (also called palmar-plantar erythrodysesthesia), diarrhoea, loss of appetite, high blood pressure, mouth sores, infection, changes in voice volume or quality, pain, weight loss, stomach pain, rash, fever and nausea.

Serious side effects, which occurred in less than one percent of patients, were liver damage, severe bleeding, blistering and peeling of skin, very high blood pressures requiring emergency treatment, heart attacks and perforations (holes) in the intestines.