A Phase II, Single-Arm Trial of Poziotinib as Salvage Treatment in Patients With Metastatic Breast Cancer Who Has HER2 or EGFR Mutation or Activated AR or EGFR Pathway

Inclusion Criteria: 1. Histologically confirmed metastatic breast cancer with measurable or evaluable disease 2. age ≥ 20 years 3. HER2 mutation or EGFR mutation/gene amplification confirmed by CancerSCAN or Activated AR pathway confirmed by RNA seq \& nCounter assay, AR expression was confirmed by immunohistochemistry(IHC) or EGFR high expression (≥ IHC 2+ \& lower ER / ≥ IHC score + and HER2 2+ or SISH negative) 4. ECOG performance status 0 - 2 5. Two or more regimens for locally recurrent or metastatic breast cancer, including an anthracycline and a taxane 6. Life expectancy ≥ 3 months 7. Progression within 6 months or less of latest chemotherapy 8. The patients must have recovered from the acute toxic effects of the treatment prior to study enrollment. Prior radiotherapy must be completed 2 weeks before study entry. 9. Adequate bone marrow function (≥ ANC 1,500/ul, ≥ platelet 100,000/ul, ≥ Hemoglobin 9.0 g/dl) 10. Adequate renal function (serum creatinine ≤ 1.5 x upper normal limit or CCr ≥ 50 ml/min) 11. Adequate liver function (serum bilirubin ≤ 1.5 x upper normal limit, AST/ALT ≤ 3 x upper normal limit) 12. No prior history of pan-HER TKI including poziotinib for metastatic breast cancer 13. Written informed consent Exclusion Criteria: 1. HER2-overexpressing breast cancer 2. Serious uncontrolled intercurrent infections 3. Serious intercurrent medical or psychiatric illness, including active cardiac disease 4. Pregnancy or breast feeding 5. Second primary malignancy(except in situ carcinoma of the cervix or adequately treated nonmelanomatous carcinoma of the skin or resected thyroid papillary carcinoma or other malignancy treated at least 5 years previously with no evidence of recurrence) 6. Documented leptomeningeal brain metastasis 7. Known brain metastases unless treated and stable 8. Peripheral neuropathy ≥ grade 3 9. Prior treatment with pan-HER TKI including poziotinib will not be allowed. 10. Use of any investigational drug within 4 weeks of the study 11. Treatment with chemotherapy or hormone therapy within 3 weeks of the study