The efficacy of TURALIO 250 mg orally twice daily administered with a low-fat meal has been established based on adequate and well-controlled studies of TURALIO 400 mg orally twice daily administered on an empty stomach and additional pharmacokinetic data that indicate there is no clinically significant difference in the relative exposure between the two dosages.

The efficacy of TURALIO was evaluated in ENLIVEN (NCT02371369), a double-blind, randomized (1:1), placebo-controlled, multicenter trial in patients with symptomatic TGCT [also referred to as giant cell tumor of the tendon sheath (GCT-TS) or pigmented villonodular synovitis (PVNS)] for whom surgical removal of the tumor would be associated with worsening functional limitation or severe morbidity. Eligible patients were required to have measurable disease per the Response Evaluation Criteria in Solid Tumors (RECIST) v1.1. Patients were randomized to placebo or TURALIO administered on an empty stomach: 400 mg in the morning and 600 mg in the evening for 2 weeks followed by 400 mg twice daily until unacceptable toxicity or disease progression. Randomization was stratified by geographic region (US vs. non-US countries) and disease location (upper extremity vs. lower extremity involvement). Patients who completed treatment in the double-blind, randomized part of the trial were eligible to advance to an open-label extension part in which all patients were given the option to receive pexidartinib.

The major efficacy outcome measure was overall response rate (ORR) as assessed by blinded independent central review (BICR) at Week 25 using RECIST v1.1. Additional efficacy outcome measures were mean change from baseline in range of motion of the affected joint at Week 25 and ORR as assessed by BICR at Week 25 using tumor volume score (TVS). Range of motion was measured as a percent of normal reference range for the affected joint. Range of motion assessments were performed by a third-party clinical assessor using a goniometer. TVS was defined in ENLIVEN as the estimated volume of the maximally distended synovial cavity or tendon sheath involved, measured in 10% increments. Patients in the placebo arm were offered TURALIO at Week 25 beginning with a 400 mg twice daily dose, as permitted by the study protocol.

A total of 120 patients were randomized, 61 to the TURALIO arm and 59 to the placebo arm. The median age was 44 years (range: 18-79); 59% were females; 88% were White; 53% had prior surgery; 88% were diagnosed with diffuse TGCT; and 9% had previously been treated with systemic therapy. Disease locations were knee (61%), ankle (18%), hip (11%), wrist (3%), foot (3%) and other (5%).

ENLIVEN demonstrated a statistically significant improvement in ORR in patients randomized to TURALIO compared with placebo. Efficacy results are summarized in Table 10. 

The analysis of mean change from baseline in range of motion at Week 25 demonstrated a statistically significant improvement in patients randomized to TURALIO compared to placebo. Figure 1 shows the change from baseline in range of motion for each patient at Week 25 (TURALIO N=45, placebo N=43). Results were excluded for 1 patient with missing baseline and 31 patients with a missing range of motion assessment at Week 25.

ORR by TVS was 56% (95% CI: 43%, 67%) in patients randomized to the TURALIO arm and 0% in patients randomized to the placebo arm; p < 0.0001.

At completion of the open-label extension part of the study in which all patients received TURALIO, the ORR using RECIST v1.1 was 61% (95% CI: 48%, 72%) in the 61 patients originally randomized to the TURALIO arm. The median duration of response was not reached (range: 4.6+, 63.4+ months) in the 37 responders.