The FDA has approved pexidartinib capsules (Turalio, Daiichi Sankyo) for the treatment of adult patients with symptomatic tenosynovial giant cell tumor (TGCT) associated with severe morbidity or functional limitations and not responsive to improvement with surgery.
TGCT is a rare tumor that affects the synovium and tendon sheaths. The condition, which mainly affects individuals between 25 and 40 years of age, with a median age of diagnosis of 30, can significantly affect a patient’s quality of life and cause severe disability. Although rarely malignant, the tumor causes the synovium and tendon sheaths to thicken and overgrow, causing damage to surrounding tissue.
Pexidartinib’s approval was based on results from a multi-center, international clinical trial of 120 patients, 59 of whom received placebo. In patients who received pexidartinib, there was a statistically significant improvement in overall response rate after 25 weeks (the primary efficacy endpoint)––38% compared to no responses in patients receiving placebo. Twenty-two of 23 responders who were followed for a minimum of six months after the initial response maintained their response for six months or more. One hundred percent of 13 responders who were followed for a minimum of 12 months after the initial response maintained their response for 12 or more months.
Pexidartinib’s prescribing information includes a Boxed Warning about the risk of serious and potentially fatal liver injury. This drug is available only through the Turalio Risk Evaluation and Mitigation Strategy (REMS) Program.
Common side effects in patients taking pexidartinib were increased lactate dehydrogenase and aspartate aminotransferase, loss of hair color, increased alanine aminotransferase, and increased cholesterol. Women who are pregnant or breastfeeding should not take pexidartinib as it can harm the developing fetus or newborn baby.
The FDA granted pexidartinib breakthrough, priority review, and orphan drug designations.
Source: FDA, August 2, 2019