ON AUGUST 2, the U.S. Food and Drug Administration (FDA) granted approval to pexidartinib (Turalio) capsules for the treatment of adult patients with symptomatic tenosynovial giant cell tumor associated with severe morbidity or functional limitations and not responsive to improvement with surgery.
Richard Pazdur, MD
“Tenosynovial giant cell tumor can cause debilitating symptoms for patients such as pain, stiffness, and limitation of movement. The tumor can significantly affect a patient’s quality of life and cause severe disability,” said Richard Pazdur, MD, Director of the FDA’s Oncology Center of Excellence and Acting Director of the Office of Hematology and Oncology Products in the FDA’s Center for Drug Evaluation and Research. “Surgery is the primary treatment option, but some patients are not eligible for surgery, and tumors can recur, even after the procedure. [This] approval is the first FDA-approved therapy to treat this rare disease.”
THE APPROVAL WAS based on the results of the multicenter international ENLIVEN clinical trial of 120 patients, 59 of whom received placebo. The primary efficacy endpoint was the overall response rate, analyzed after 25 weeks of treatment. The clinical trial demonstrated a statistically significant improvement in overall response in patients who received pexidartinib, with an overall response rate of 38% vs no responses in patients who received placebo. The complete response rate was 15%, and the partial response rate was 23%. A total of 22 of 23 responders who had been followed for a minimum of 6 months after initial response maintained their response for 6 or more months, and 13 of 13 responders who had been followed for a minimum of 12 months after initial response maintained their response for 12 or more months.
Common side effects reported in patients taking pexidartinib were increased lactate dehydrogenase, increased aspartate aminotransferase, loss of hair color, increased alanine aminotransferase, and increased cholesterol. Additional side effects included neutropenia, increased alkaline phosphatase, decreased lymphocytes, eye edema, decreased hemoglobin, rash, dysgeusia, and decreased phosphate.
The prescribing information for pexidartinib includes a Boxed Warning to advise health-care professionals and patients about the risk of serious and potentially fatal liver injury. Health-care professionals should monitor liver tests prior to beginning treatment and at specified intervals during treatment; if liver tests become abnormal, pexidartinib may need to be withheld, the dose reduced, or treatment permanently discontinued, depending on the severity of the liver injury. Pexidartinib is available only through the Turalio Risk Evaluation and Mitigation Strategy Program. ■