(P 403) MEDICAL MANAGEMENT OF TENOSYNOVIAL GIANT CELL TUMOR

Objective: Tenosynovial giant cell tumor (TGCT) is a benign neoplasm of the synovia, bursae, and tendon sheaths. Guidelines recommend active surveillance for manageable symptoms. Symptomatic patients (pts) have been treated with surgery, but complete removal of tumors is not always feasible due to their diffuse nature and high risk of morbidity, with postsurgery recurrence rate of 20%-50%.
Multiple colony-stimulating factor 1 receptor inhibitors (CSF1Ris) have emerged for symptomatic pts, with pexidartinib (pexi) and vimseltinib (vim) approved. Here, we review phase 3 reports for pexi, vim, and pimicotinib (pimi).

Methods: PubMed was searched for publications associated with TGCT, CSF-1Ri, therapies for treatment of TGCT, and known guidelines, with a focus on phase 3 trials and postmarket analyses. Additional targeted searches for ongoing clinical trials were performed.

Results: Three phase 3 TGCT studies were identified (total N=337). The studies enrolled adults with histologically confirmed TGCT for which surgery was not recommended due to risk of dysfunction and morbidity. Pts had measurable disease per RECIST and moderate pain or stiffness. The primary endpoint for all studies was objective response rate (ORR) per RECIST v1.1 at Week 25. Key secondary endpoints were ORR by tumor volume score (TVS), range of motion (ROM), worst stiffness, Brief Pain Inventory (BPI) worst pain, and PROMIS physical function (PF) at Week 25.
Baseline characteristics were similar, with 59%-68% female, ROM of 62.5%-63.0%, PROMIS-PF of 37.5-39.0, and worst stiffness numeric rating of 5.1-5.9. Results are shown in Table 1.

Conclusion: CSF1Ris show efficacy in TGCT. Pts should be monitored for potential side effects that are different for each presented drug. Further research to understand long-term side effects and duration of response will be paramount to optimize therapeutic strategies for pts with TGCT. Efforts to increase awareness (eg, input from pt advocacy groups) are essential.