In the Clinic

Our investigational drug, OP-1250, is an estrogen receptor antagonist. It was developed to compete with estrogen for binding to the receptor and keep it in a completely inactive state.

OP-1250 is currently in Phase 1/2 development as a single-agent treatment for estrogen receptor-positive, HER2-negative metastatic breast cancer (ER+, HER2- MBC).

Our Pipeline

Target Patient Population



Phase I

Phase II

Phase III


Metastatic Breast Cancer

ER+, HER2- MBC (with and without CNS metastases)

ER+, HER2- MBC(1) (combination with CDK4/6i)(1)

ER+, HER2- MBC with PIK3CA mutated (combination with PIK3αi)(1)

ER+, Pre-menopausal(1)

ER+ with ESR1 mutation(1)

HER2+ Metastatic Breast Cancer with CNS mets

ER+, HER2+ MBC with CNS metastases

Gynecology — Oncology

Endometrial Cancer(1)

Gynecologic malignancies

Clinical Trials

The first clinical trial is an ongoing Phase 1/2, open-label, multi-center, dose-escalation and expansion study evaluating the safety, pharmacokinetics, pharmacodynamics, and anti-tumor activity of daily oral administration of OP-1250.

Get in Touch

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