A Study of THE-630 in Patients With Advanced Gastrointestinal Stromal Tumors (GIST)

The drug being tested in this study is called THE-630, an orally administered KIT tyrosine kinase inhibitor. The study will be conducted in two parts: a dose escalation phase, followed by an expansion phase. The patient population of the initial dose escalation phase (Phase 1) of the trial will include patients with unresectable or metastatic GIST. Patients must have disease progression on or be intolerant to imatinib therapy and have also received at least 1 of the following: sunitinib, regorafenib, ripretinib, or avapritinib. The primary objective of the dose escalation phase is to determine the safety profile of oral THE-630, including the dose limiting toxicities (DLTs), maximum tolerated dose (MTD), and the recommended Phase 2 dose (RP2D). Once a recommended dose has been determined in the escalation phase, the expansion phase (Phase 2) will enroll 3 cohorts of patients with unresectable or metastatic GIST defined by prior therapy: * Cohort 1: Patients with unresectable or metastatic GIST who have progressed on or are intolerant to imatinib, sunitinib, regorafenib and ripretinib (≥5th Line). * Cohort 2: Patients with unresectable or metastatic GIST who have progressed on or are intolerant to imatinib, sunitinib and 0-1 additional lines of therapy in the advanced/metastatic setting (3rd-4th Line). * Cohort 3: Patients with unresectable or metastatic GIST who have progressed on or are intolerant to imatinib (including in the adjuvant setting) and who have not received additional systemic therapy for advanced GIST (2nd Line). The safety and tolerability of orally administered THE-630 will continue to be assessed in the expansion cohorts. However, the primary objective of the expansion component of the trial is to evaluate the anti-tumor activity of THE-630 in these GIST patient populations.