(NAVIGATOR) Study of BLU-285 in Patients With Gastrointestinal Stromal Tumors (GIST) and Other Relapsed and Refractory Solid Tumors

Inclusion Criteria

• For Part 1: Histologically- or cytologically-confirmed diagnosis of unresectable GIST or another advanced solid tumor. Patients with unresectable GIST must have disease that has progressed following imatinib and at least 1 of the following: sunitinib, regorafenib, sorafenib, dasatinib, pazopanib or an experimental kinase-inhibitor agent, or disease with a D842 mutation in the PDGFRα gene. Patients with an advanced solid tumor other than GIST must have relapsed or refractory disease without an available effective therapy. OR For Part 2:
• Group 1: Patients must have a confirmed diagnosis of unresectable GIST that has progressed following imatinib and at least 1 of the following: sunitinib, regorafenib, sorafenib, dasatinib, pazopanib, or an experimental kinase-inhibitor agent, and the patient does not have a D842V mutation in PDGFRα.
• Group 2: Patients must have a confirmed diagnosis of unresectable GIST with a D842V mutation in the PDGFRα gene. The PDGFRα mutation will be identified by local or central assessment, either in an archival tissue sample or a new tumor biopsy obtained prior to treatment with avapritinib.
• Group 3: Patients must have a confirmed diagnosis of unresectable GIST that has progressed and/or patients must have experienced intolerance to imatinib and not received additional kinase-inhibitor therapy. Patients must not have a known D842V mutation in PDGFRα.
• Groups 1, 2 and 3: At least 1 measurable lesion defined by mRECIST 1.1 for patients with GIST.
• Groups 1 and 2: A tumor sample (archival tissue or a new tumor biopsy) has been submitted for mutational testing.
• Eastern Cooperative Oncology Group (ECOG) performance status of 0-2

Exclusion Criteria

• QT interval corrected using Fridericia's formula (QTcF) >450 milliseconds
• Platelet count <90,000/mL
• Absolute neutrophil count <1000/mL
• Hemoglobin <9 g/dL
• Aspartate aminotransferase (AST) or alanine aminotransferase (ALT) >3 x the upper limit of normal (ULN) if no hepatic metastases are present; >5 × ULN if hepatic metastases are present
• Total bilirubin >1.5 × ULN; >3 × ULN with direct bilirubin, >1.5 × ULN in the presence of Gilbert's Disease
• Estimated (Cockroft-Gault formula) or measured creatinine clearance <40 mL/min Brain malignancy or metastases to the brain
• History of a seizure disorder or requirement for anti-seizure medication
• Group 3: Patients known to be KIT wild type.