Study to Evaluate Discontinuation and Re-Treatment in Participants With Tenosynovial Giant Cell Tumor (TGCT) Previously Treated With Pexidartinib

Inclusion Criteria:

* Currently enrolled and on pexidartinib treatment in one of the following studies: Study PLX108-10 (ENLIVEN), Study PLX108-01, Study PL3397-A-A103 or Study PL3397-A-U126.
* Willing and able to complete the PROMIS Physical Function Scale and EQ-5D-5L throughout the study.
* Willing and able to provide written informed consent prior to any study-related procedures and to comply with all study requirements.
* Females of reproductive potential must have a negative urine pregnancy test at Screening/Baseline (to be confirmed by a serum pregnancy test taken on the last treatment visit of their prior study). They are advised to use an effective, non-hormonal method of contraception during treatment with pexidartinib and for 1 month after the last dose. Males with female partners of reproductive potential should be advised to use an effective method of contraception during treatment with pexidartinib and for 1 month after the last dose. Female partners of male patients should concurrently use effective contraceptive methods (hormonal or non-hormonal).

Note: A female is considered of reproductive potential following menarche and until becoming postmenopausal (no menstrual period for a minimum of 12 months) unless permanently sterile (undergone a hysterectomy, bilateral salpingectomy or bilateral oophorectomy) with a confirmed by follicle stimulating hormone (FSH) test level \>40 mIU/mL.

* Male participants must not freeze or donate sperm starting at Screening and throughout the study period, and for at least 5 half-lives or 1 month after the final study drug administration, whichever is longer. Female participants must not donate, or retrieve for their own use, ova from the time of Screening and throughout the study treatment period, and for at least 1 month or 5 half-lives after the final study drug administration, whichever is longer.

Exclusion Criteria:

* Participant has a clinically significant abnormality identified by the Investigator at Screening on physical examination, laboratory tests, or electrocardiogram (ECG) which, in the judgement of the Investigator, would preclude the participant's safe completion of the study.
* Exposure to another investigational drug or current participation in other therapeutic investigational procedures, besides pexidartinib studies, within 1 month prior to start of study treatment. Any known contraindication to treatment with, including hypersensitivity to, the study drug(s) or excipients in pexidartinib.