To learn if the study drugs, tucatinib and adotrastuzumab emtansine (T-DM1), can help to control solid tumors that have spread to the brain.
Histologically confirmed HER2-positive metastatic solid tumor. HER2 positivity defined as HER2 overexpression by immunohistochemistry (IHC) 3+ or 2+ and fluorescence in situ hybridization (FISH) positive and/or HER2 amplification by in situ hybridization (ISH) or next generation sequencing (NGS) and/or activating ERBB2 mutation(s) (verified by MDACC Precision Oncology Decision Support).
Untreated brain metastases not requiring immediate local CNS therapy
Previously treated brain metastases with progression of previous lesions or new lesions, but not requiring immediate local CNS therapy
At least one measurable untreated brain lesion ≥0.5 cm and <3.0 cm in the longest axis
Any untreated brain lesions >3.0 cm in size
Any brain lesion thought to require immediate local therapy, including (but not limited to) a lesion in an anatomic site where increase in size or possible treatment-related edema may pose risk to the patient (e.g., brainstem lesions). Patients who undergo local treatment for such lesions may still be eligible for the study based on inclusion criteria #2.
Ongoing use of systemic corticosteroids for control of symptoms of brain metastases at a total daily dose of >4 mg of dexamethasone (or equivalent).
Poorly controlled (>1/week) generalized or complex partial seizures, or manifestation of neurologic progression due to brain metastases notwithstanding CNS-directed therapy.