The purpose of this expanded access program (EAP) is to provide investigational bezuclastinib so that it can be coadministered with sunitinib to patients with a diagnosis of gastrointestinal stromal tumors (GIST) with no comparable or satisfactory alternative therapy options. The combination of bezuclastinib and sunitinib provides broad inhibition of all primary and secondary KIT mutations that commonly occur in GIST.

Inclusion Criteria:

• Able to provide written informed consent and commit to recommended EAP assessments.
• ≥18 years of age.
• Able to swallow tablets.
• Histologically confirmed locally advanced, metastatic, and/or unresectable GIST.
• Intolerant to imatinib or received prior imatinib therapy for treatment of advanced, metastatic, and/or unresectable GIST that resulted in disease progression.
• Meet clinically acceptable local laboratory results.

Exclusion Criteria:

• Patients who are eligible for and capable of participating in and/or enrolled in an on-going bezuclastinib clinical trial.
• Prior or known intolerance to sunitinib.
• Patients who have previously participated in a bezuclastinib clinical trial.
• Patients with persistent > Grade 2 toxicities from prior therapy.
• Known PDGFR driving mutations or known SDH deficiency.
• Pregnant or currently breastfeeding.

Other protocol-defined criteria apply.