Trial Outcomes & Findings for Phase 3 Study of Pexidartinib for Pigmented Villonodular Synovitis (PVNS) or Giant Cell Tumor of the Tendon Sheath (GCT-TS) (NCT NCT02371369)

Part 1 was a double-blind, randomized, Pexidartinib or placebo in participants with symptomatic TGCT for whom surgical resection would be associated with potentially worsening functional limitation or severe morbidity. Part 2 is a long-term treatment phase in which all eligible participants received open-label Pexidartinib.

Participants were screened for inclusion and exclusion criteria. Screening procedures were performed after consent was obtained and within the 42 days before the first dose of study drug, unless otherwise noted.

Phase 3 Study of Pexidartinib for Pigmented Villonodular Synovitis (PVNS) or Giant Cell Tumor of the Tendon Sheath (GCT-TS)

Complete response (CR) and partial responses (PR) were assessed based on centrally-read magnetic resonance imaging (MRI) scans and Response Evaluation Criteria in Solid Tumors, version 1.1 (RECIST 1.1). A CR was defined as disappearance of all tumors and a PR was defined as at least a 30% decrease in the sum of diameters of target tumors using the baseline sum diameters as the reference.

Range of motion (ROM) of the joint was assessed by a qualified, independent, and blinded or third-party assessors at the clinical site. Measurements were recorded in degrees. At baseline, the plane of movement with the smallest relative value (worst) was identified and this plane was used for evaluating the relative change of motion subsequently. Only the plane with the worst impaired ROM at baseline was selected for subsequent analyses.

Complete response (CR) and partial response (PR) were assessed using tumor volume score (TVS). A CR was defined as disappearance of all tumors and a PR was defined as at least a 30% decrease in the sum of diameters of target tumors using the baseline sum diameters as the reference. TVS is a semi-quantitative MRI scoring system that describes tumor mass and is based on 10% increments of the estimated volume of the maximally distended synovial cavity or tendon sheath involved. A tumor that is equal in volume to that of a maximally distended synovial cavity or tendon sheath was scored 10; a score of 0 indicated no evidence of tumor.

The Patient-reported Outcomes Measurement Information System (PROMIS) physical function scale was used to assess physical function of the upper and lower limbs. The scale ranged from 1 defined as 'unable to do' or 'cannot do' to 5 defined as 'without any difficulty' or 'not at all', where higher scores represent better outcomes.

The Worst Stiffness Numeric Rating Scale (NRS) was a 1-item, self-administered questionnaire assessing the "worst" stiffness in the last 24 hours. The NRS for this item ranged from 0 (no stiffness) to 10 (stiffness as bad as you can imagine).

The Brief Pain Inventory (BPI) Worst Pain Numeric Rating Scale Score (NRS) was a 1-item, self-administered questionnaire assessing the "worst" pain in the last 24 hours. The NRS for this item ranged from 0 (no pain) to 10 (pain as bad as you can imagine).

Duration of response (DOR) based on RECIST 1.1 is defined as the date of the first recorded response to the first date of documented disease progression. The overall number of responses and the number of participants with and without disease progression was assessed.

Tumor Volume Score (TVS) is a semi-quantitative MRI scoring system that describes tumor mass and is based on 10% increments of the estimated volume of the maximally distended synovial cavity or tendon sheath involved. A tumor that is equal in volume to that of a maximally distended synovial cavity or tendon sheath was scored 10; a score of 0 indicated no evidence of tumor. The overall number of responses and the number of participants with and without disease progression was assessed.

Duration of response (DOR) based on RECIST 1.1 is defined from the date of the first recorded evidence of response to the first date of documented disease progression.

Duration of response (DOR) based on TVS is defined from the date of the first recorded evidence of response to the first date of documented disease progression.

Treatment-emergent adverse events (TEAEs) were defined as adverse events that started or worsened after the first dose of treatment and within 28 days after the last dose. The National Cancer Institute Common Terminology Criteria for Adverse Events (NCI CTCAE) version 4.0 was used to grade adverse events. Any Grade and Grade ≥3 (severe) TEAEs are reported. TEAEs were coded using MedDRA version 17.1.

Complete (CR) and partial responses (PR) were assessed based on centrally-read magnetic resonance imaging (MRI) scans and Response Evaluation Criteria in Solid Tumors, version 1.1 (RECIST 1.1). A CR was defined as disappearance of all tumors and a PR was defined as at least a 30% decrease in the sum of diameters of target tumors using the baseline sum diameters as the reference.

Range of motion (ROM) of the joint was assessed by a qualified, independent, and blinded or third-party assessors at the clinical site. Measurements were recorded in degrees. At baseline, the plane of movement with the smallest relative value (worst) was identified and this plane was used for evaluating the relative change of motion subsequently. Only the plane with the worst impaired ROM at baseline was selected for subsequent analyses.

The Patient-reported Outcomes Measurement Information System (PROMIS) physical function scale was used to assess physical function of the upper and lower limbs. The scale ranged from 1 defined as 'unable to do' or 'cannot do' to 5 defined as 'without any difficulty' or 'not at all', where higher scores represent better outcomes.

The Worst Stiffness Numeric Rating Scale (NRS) was a 1-item, self-administered questionnaire assessing the "worst" stiffness in the last 24 hours. The NRS for this item ranged from 0 (no stiffness) to 10 (stiffness as bad as you can imagine).

The Brief Pain Inventory (BPI) Worst Pain NRS was a 1-item, self-administered questionnaire assessing the "worst" pain in the last 24 hours. The NRS for this item ranged from 0 (no pain) to 10 (pain as bad as you can imagine).

Best overall response (CR or PR) was assessed using tumor volume score (TVS) in the ITT population. Tumor Volume Score is a semi-quantitative MRI scoring system that describes tumor mass and is based on 10% increments of the estimated volume of the maximally distended synovial cavity or tendon sheath involved. A tumor that is equal in volume to that of a maximally distended synovial cavity or tendon sheath was scored 10; a score of 0 indicated no evidence of tumor.