A Dose Escalation/Expansion Study of Oral OP-1250 in Subjects With Advanced and/or Metastatic HR+, HER2- Breast Cancer

A Dose Escalation/Expansion Study of Oral OP-1250 in Subjects With Advanced and/or Metastatic HR+, HER2- Breast Cancer

A Phase I Dose Escalation and Dose Expansion and Phase II Monotherapy Open-label, First-in-Human, Multicenter Study of OP-1250 in Adult Subjects With Advanced and/or Metastatic Hormone Receptor (HR)-Positive, HER2-negative Breast Cancer

This clinical trial is a Phase I dose escalation and dose expansion and Phase II monotherapy open-label, first-in-human, multicenter study of OP-1250 in adult subjects with advanced and/or metastatic hormone receptor (HR)-positive, her2-negative breast cancer.

This is a Phase I dose escalation and dose expansion and Phase II monotherapy open--label, first--in--human study to determine the dose limiting toxicity (DLT), maximum tolerated dose (MTD) and/or recommended Phase II dose (RP2D), to characterize the safety and pharmacokinetic (PK) profile, and to estimate the preliminary anti-tumor activity of OP-1250 as a single agent in adult subjects with hormone receptor (HR)-positive/human epidermal growth factor receptor 2 (HER2)-negative metastatic or locally advanced breast cancer. This study comprises 2 Phases: Phase I (Part A [Dose Escalation] and Part B [Dose Expansion]) and Phase II. Additionally, all subjects (Phase I and Phase II) will be eligible to participate in 1 of 2 sub-studies. Patients must have received at least 1 prior hormonal regimen and at least 6 months of a prior continuous endocrine therapy for locally advanced or metastatic disease. Patients will be evaluated for treatment emergent adverse events (AEs) during study participation, and toxicity will be assessed according to the National Cancer Institute (NCI) Common Terminology Criteria for Adverse Events, Version 5.0.

Phase I Part A will evaluate the safety and pharmacokinetics (PK)of a range of OP-1250 doses to identify the maximum tolerated dose (MTD) and/or recommended Phase 2 dose (RP2D). Phase I Part B will evaluate the safety and PK of OP-1250 to confirm the RP2D dose.

This portion of the study further explores the clinical activity, safety, and PK of OP-1250 monotherapy at the RP2D and will estimate preliminary anti-tumor efficacy in 3 cohorts. Cohort A will enroll subjects with measurable disease without evidence of CNS metastases; Cohort B will enroll subjects with non-measurable (evaluable) disease without evidence of CNS metastases; and Cohort C will enroll subjects with evaluable disease (measurable and non-measurable) with CNS metastases.

To determine the maximum tolerated dose (MTD) and/or recommended Phase II dose (RP2D) of OP-1250, the incidence of DLTs will be assessed.

Characterize the incidence, nature and severity of treatment emergent adverse events (TEAEs) and serious adverse events (SAEs) of OP-1250

Characterize the incidence, nature and severity of TEAEs and SAEs of OP-1250 according to NCI-CTCAE version 5.0

Tumor response will be evaluated in patients with measurable or evaluable disease, using RECISTv1.1 guidelines

Inclusion Criteria: Eastern Cooperative Oncology Group (ECOG) performance status of 0 or 1 Must have received at least 1 prior hormonal regimen and at least 6 months of a prior continuous endocrine therapy for locally advanced or metastatic disease Must not have received prior oral endocrine therapy < 2 weeks prior to first dose Must not have received prior, chemotherapy in 2 weeks or within 5 half-lives whichever is earlier, antibody therapy within 4 weeks or investigational therapy within 4 weeks or 5 half-lives whichever is earlier, prior to the first dose Adequate hepatic function Adequate renal function Normal coagulation panel Willingness to use effective contraception Exclusion Criteria: Gastrointestinal disease Significant renal disease Significant cardiovascular disease Significant ECG abnormalities Ongoing systemic bacterial, fungal, or viral infection (requiring antimicrobial therapy) Pregnancy or breastfeeding