The U.S. Food and Drug Administration approved the novel oral therapy Turalio™ (pexidartinib) capsules for the treatment of adults with symptomatic tenosynovial giant cell tumor (TGCT) associated with severe morbidity or functional limitations that has not improved with surgery.
TGCT is a rare tumor that affects the synovium and tendon sheaths; while often benign, the tumor can cause the synovium and tendon sheaths to thicken and overgrow, causing damage to surrounding tissue. Pexidartinib is the first systemic therapy for TGCT and acts as an inhibitor of colony stimulating factor-1 receptor.
Improved response with pexidartinib
The approval was based on the results of the multicenter, international, placebo-controlled, phase III ENLIVEN study that included 120 patients (median age, 45 years; 88% white; 59% female) who received pexidartinib (n=61) or placebo (n=59).
Pexidartinib is CSF1R inhibitor. May be important for countering immune suppression
— Razelle Kurzrock, MD (@Dr_R_Kurzrock) August 2, 2019
At 25 weeks, the overall response rate (primary endpoint) was 38% for patients receiving pexidartinib and 0% for patients receiving placebo (P<0.0001). With pexidartinib, the complete response rate was 15% and the partial response rate was 23%. Twenty-two of 23 responders who were followed for a minimum of six months after initial response maintained their response for six or more months. All 13 responders who were followed for a minimum of 12 months after initial response maintained their response for 12 or more months.
The most common adverse events (AEs) associated with pexidartinib are increased lactate dehydrogenase, increased aspartate aminotransferase, loss of hair color, increased alanine aminotransferase, and increased cholesterol. Other AEs include neutropenia, increased alkaline phosphatase, decreased lymphocytes, eye edema, decreased hemoglobin, rash, dysgeusia, and decreased phosphate.
Pexidartinib carries a Boxed Warning for the risk of serious and potentially fatal liver injury. Healthcare professionals should monitor liver tests prior to beginning treatment and at specified intervals during treatment.
Studies are ongoing to assess the liver toxicity concerns.