A Study of BDTX-189, an Orally Available Allosteric ErbB Inhibitor, in Patients With Advanced Solid Tumors.

Main Inclusion Criteria: * Histologically- or cytologically-confirmed locally advanced or metastatic solid tumor with documented recurrence or disease progression from standard anticancer therapy in the advanced/metastatic setting * No standard therapy available or standard therapy is considered unsuitable or intolerable according to the Investigator and consultation with the Medical Monitor Phase 1 Only: * Solid tumor patients with alterations that may be associated with antitumor activity based on preclinical data for BDTX-189 such as: 1. Allosteric HER2 or HER3 mutation(s) 2. EGFR or HER2 exon 20 insertion mutation(s) 3. HER2 amplified or overexpressing tumors 4. EGFR exon 19 deletion or L858R mutation Eligible mutations must be determined by a validated next-generation sequencing (NGS) test routinely used by each institution and performed in a CLIA-certified or equivalent laboratory. * Adequate archival tumor tissue or willing to undergo pretreatment biopsy * Measurable disease according to RECIST version 1.1 Main Exclusion Criteria: * Clinical laboratory values meeting the following criteria within 4 weeks (28 days) prior to baseline: 1. Serum creatinine ≥1.5 × upper limit of normal (ULN) or calculated creatinine clearance ≤60 mL/min using Cockcroft-Gault equation 2. Total bilirubin ≥1.5 × ULN or ≥3.0 × ULN in the presence of documented Gilbert's syndrome 3. Aspartate aminotransferase (AST) or alanine aminotransferase (ALT) ≥2.5 × ULN, or AST or ALT ≥5.0 × ULN in the presence of liver metastases 4. Hematologic function: 1. Absolute neutrophil count (ANC) ≤1000 cells/μL 2. Hemoglobin ≤8.5 g/dL or 5.28 mmol/L 3. Platelet count ≤75,000/μL * Significant cardiovascular disease, including: 1. Cardiac failure New York Heart Association Class III or IV, or left ventricular ejection fraction (LVEF) \<50% or below the lower limit of the Institution's normal range 2. Myocardial infarction, severe or unstable angina within 6 months prior to baseline 3. Significant thrombotic or embolic events within 3 months prior to baseline 4. History or presence of any uncontrolled cardiovascular disease 5. Personal or family history of long QT syndrome * ECG findings meeting any of the following criteria: 1. Evidence of second- or third-degree atrioventricular block 2. Clinically significant arrhythmia (as determined by the Investigator) 3. QTcF interval of \>470 msec * Leptomeningeal or untreated and/or symptomatic CNS malignancies (primary or metastatic) * Women who are pregnant or breast-feeding * Taking or unable to discontinue proton pump inhibitors within 1 week prior to baseline * Known concurrent KRAS mutation * Known tumor-harboring resistance mutations including EGFR T790M or C797S mutations or HER2 C805S mutation