TAK-228 Plus Tamoxifen in Patients With ER-Positive, HER2-negative Breast Cancer

The mTOR pathway is commonly dysregulated in ER-positive breast cancers and represents a key resistance mechanism to endocrine therapy such as tamoxifen. We plan to target the mTOR pathway with mTORC1/2 inhibitor TAK-228 to overcome tamoxifen resistance in early-stage ER-positive breast cancer. An open label phase II clinical trial will be conducted to determine the efficacy, toxicity, and safety of TAK-228 plus tamoxifen in patients with newly diagnosed ER-positive, HER2-negative breast cancer. TAK-228 (30 mg weekly) plus tamoxifen (20 mg daily) will be administered for 16 weeks. Patients will undergo tumor biopsy before starting the study treatment and after 6 weeks of study treatment. Blood samples for pharmacokinetics analysis will be obtained 1 hour before and after TAK-228 dosing on days 1 and 15 of the study.