Biotheryx, Inc.
The purpose of this study is to test BTX-9341 alone or in combination with fulvestrant (a currently marketed medication for breast cancer) in participants with advanced and/or metastatic hormone receptor positive (HR+)/human epidermal growth factor receptor 2 negative (HER2-) breast cancer. The study includes a dose escalation part (Part A) where small groups of participants will receive increasing doses of BTX-9341 or BTX-9341 + fulvestrant followed by a dose expansion part (Part B) where participants will receive the dose of BTX-9341 selected in Part A + fulvestrant.
This first-in-human (FIH), Phase 1 study of BTX-9341 is multicenter, nonrandomized, and open-label to evaluate the safety, tolerability, pharmacokinetics (PK), and preliminary efficacy of BTX-9341 in participants with advanced and/or metastatic HR+/HER2 breast cancer. The study will include a dose escalation part (Part A) followed by a dose expansion part (Part B). During Part A, BTX-9341 will initially be dose escalated alone and then in combination with fulvestrant. A single combination therapy cohort of BTX-9341 + fulvestrant will be further explored in Part B. BTX-9341 will be administered…
Inclusion Criteria: * Metastatic and/or locally advanced HR+/HER2- breast cancer (dose escalation: measurable disease and/or at least 1 lytic or mixed \[lytic + sclerotic\] bone lesion that can be assessed by CT or MRI or non-measurable disease \[including bone lesions\]; dose expansion: measurable disease) * Dose escalation: (a) received not more than 1 chemotherapy in the metastatic/advanced setting; (b) no limit to the lines of endocrine therapy (monotherapy or combination therapy) in the metastatic setting; (c) received CDK4/6 inhibitor therapy * Dose expansion: (a) received not more than…
Daily oral dose in 28-day cycles until maximum tolerated dose (MTD) or maximum evaluable dose (MED) determined
500 mg intramuscular injections on Day 15 and then every 28 days
Daily oral dose in 28-day cycles using dose determined in Part A