A Phase 1 Study of Oral OP-1250 in Combination With Palbociclib in HR+/HER2- Breast Cancer Patients

November 19, 2025 updated by: Olema Pharmaceuticals, Inc.

A Phase 1 Dose Escalation and Expansion Open-label, Multicenter, Study of OP-1250 in Combination With the CDK4/6 Inhibitor Palbociclib in Adult Subjects With Advanced or Metastatic HR-positive, HER2-negative Breast Cancer

This is an open-label, Phase 1b dose escalation and expansion study to determine the maximum tolerated dose (MTD) of OP-1250 in combination with palbociclib (Ibrance®️, Pfizer Inc.). Purpose of study is to evaluate the safety and pharmacokinetic (PK) profile, and estimate the preliminary anti-tumor activity of the combination in adult subjects with hormone receptor-positive (ER+ / HER2-) advanced or metastatic breast cancer (MBC).

Study Overview

Status

Status

Indicates the current recruitment status or the expanded access status.
Active, not recruiting

Conditions

Conditions

The disease, disorder, syndrome, illness, or injury that is being studied. On ClinicalTrials.gov, conditions may also include other health-related issues, such as lifespan, quality of life, and health risks.

Intervention / Treatment

Intervention / Treatment

A process or action that is the focus of a clinical study. Interventions include drugs, medical devices, procedures, vaccines, and other products that are either investigational or already available. Interventions can also include noninvasive approaches, such as education or modifying diet and exercise.

Study Type

Study Type

Describes the nature of a clinical study. Study types include interventional studies (also called clinical trials), observational studies (including patient registries), and expanded access.
Interventional

Enrollment (Actual)

Enrollment

The number of participants in a clinical study. The "anticipated" enrollment is the target number of participants that the researchers need for the study.
60

Phase

Phase

The stage of a clinical trial studying a drug or biological product, based on definitions developed by the U.S. Food and Drug Administration (FDA). The phase is based on the study's objective, the number of participants, and other characteristics. There are five phases: Early Phase 1 (formerly listed as Phase 0), Phase 1, Phase 2, Phase 3, and Phase 4. Not Applicable is used to describe trials without FDA-defined phases, including trials of devices or behavioral interventions.
  • Phase 1

Contacts and Locations

This section provides the contact details for those conducting the study, and information on where this study is being conducted.

Study Contact

Study Contact

The name and contact information for the person who can answer enrollment questions for a clinical study. Each location where the study is being conducted may also have a specific contact, who may be better able to answer those questions.

Study Locations

  • Australia
    • New South Wales
      • Waratah, New South Wales, Australia, 2298
        • Clinical Trial Site
      • Westmead, New South Wales, Australia, 2145
        • Clinical Trial Site
    • Queensland
      • South Brisbane, Queensland, Australia, 4101
        • Clinical Trial Site
      • Southport, Queensland, Australia, 4215
        • Clinical Trial Site
    • Victoria
      • Clayton, Victoria, Australia, 3168
        • Clinical Trial Site
      • Frankston, Victoria, Australia, 3199
        • Clinical Trial Site
      • Geelong, Victoria, Australia, 3220
        • Clinical Trial Site
    • Western Australia
      • Nedlands, Western Australia, Australia, 6009
        • Clinical Trial Site

Participation Criteria

Researchers look for people who fit a certain description, called eligibility criteria. Some examples of these criteria are a person's general health condition or prior treatments.

Eligibility Criteria

Eligibility Criteria

The key requirements that people who want to participate in a clinical study must meet or the characteristics they must have. Eligibility criteria consist of both inclusion criteria (which are required for a person to participate in the study) and exclusion criteria (which prevent a person from participating). Types of eligibility criteria include whether a study accepts healthy volunteers, has age or age group requirements, or is limited by sex.

Ages Eligible for Study

18 years and older (Adult, Older Adult)

Accepts Healthy Volunteers

No

Description

Inclusion Criteria:

  • Confirmed and evaluable locally advanced or metastatic breast cancer
  • Eastern Cooperative Oncology Group (ECOG) performance status of 0 or 1
  • Must not have received prior oral endocrine or targeted therapy ≤ 2 weeks prior to first dose
  • Must not have received prior chemotherapy, antibody therapy, or investigational therapy ≤ 4 weeks prior to the first dose
  • Prior radiotherapy must have been completed 2 weeks prior to first dose
  • Adequate safety laboratory tests
  • Willingness to use effective contraception

Exclusion Criteria:

  • Gastrointestinal disease
  • Significant hepatic disease
  • Significant cardiovascular disease
  • Significant ECG abnormalities
  • History of pulmonary embolism or high risk of thrombosis
  • Known HIV infection
  • Active infection (requiring antimicrobial therapy)
  • Pregnant

Study Plan

This section provides details of the study plan, including how the study is designed and what the study is measuring.

How is the study designed?

Design Details

  • Primary Purpose: Treatment
  • Allocation: Non-Randomized
  • Interventional Model: Sequential Assignment
  • Masking: None (Open Label)

Arms and Interventions

Participant Group / Arm

Participant Group / Arm

A group or subgroup of participants in a clinical trial that receives a specific intervention/treatment, or no intervention, according to the trial's protocol.
Intervention / Treatment

Intervention / Treatment

A process or action that is the focus of a clinical study. Interventions include drugs, medical devices, procedures, vaccines, and other products that are either investigational or already available. Interventions can also include noninvasive approaches, such as education or modifying diet and exercise.
Experimental: Dose Escalation
This portion of the study will evaluate the safety and pharmacology of a range of OP-1250 doses administered daily with Palbociclib in subjects with advanced and/or metastatic hormone receptor (HR)-positive, HER2-negative breast cancer
Drug: Palbociclib
Palbociclib is an approved CDK 4/6 Inhibitor drug
Other Names:
  • Ibrance®️
Drug: Palazestrant
Complete Estrogen Receptor Antagonist
Other Names:
  • OP-1250
Experimental: Dose Expansion
This portion of the study further explores the clinical activity, safety and pharmacology of OP-1250 in combination with Palbociclib and estimates preliminary data of anti-tumor efficacy
Drug: Palbociclib
Palbociclib is an approved CDK 4/6 Inhibitor drug
Other Names:
  • Ibrance®️
Drug: Palazestrant
Complete Estrogen Receptor Antagonist
Other Names:
  • OP-1250

What is the study measuring?

Primary Outcome Measures

Primary Outcome Measures

In a clinical study's protocol, the planned outcome measure that is the most important for evaluating the effect of an intervention/treatment. Most clinical studies have one primary outcome measure, but some have more than one.
Outcome Measure
Time Frame
Incidence of Dose Limiting Toxicities
Time Frame: From Cycle 1 Day 1 through C1 Day 28
From Cycle 1 Day 1 through C1 Day 28
Characterization and Incidence in Adverse Events and Serious Adverse Events
Time Frame: From initial inform consent date through 30 days post last dose
From initial inform consent date through 30 days post last dose
Plasma levels of OP-1250 and Palbociclib
Time Frame: Up to 9 months
Up to 9 months

Collaborators and Investigators

This is where you will find people and organizations involved with this study.

Sponsor

Sponsor

The organization or person who initiates the study and who has authority and control over the study.
Olema Pharmaceuticals, Inc.

Collaborators

Collaborators

An organization other than the sponsor that provides support for a clinical study. This support may include activities related to funding, design, implementation, data analysis, or reporting.
Pfizer

Investigators

Investigators

A researcher involved in a clinical study. Related terms include site principal investigator, site sub-investigator, study chair, study director, and study principal investigator.
  • Study Director: Sue Johnson, Olema Pharmaceuticals, Inc.

Study record dates

These dates track the progress of study record and summary results submissions to ClinicalTrials.gov. Study records and reported results are reviewed by the National Library of Medicine (NLM) to make sure they meet specific quality control standards before being posted on the public website.

Study Major Dates

Study Start (Actual)

Study Start

The actual date on which the first participant was enrolled in a clinical study. The "anticipated" study start date is the date that the researchers think will be the study start date.
December 10, 2021

Primary Completion (Estimated)

Primary Completion

The date on which the last participant in a clinical study was examined or received an intervention to collect final data for the primary outcome measure. Whether the clinical study ended according to the protocol or was terminated does not affect this date. For clinical studies with more than one primary outcome measure with different completion dates, this term refers to the date on which data collection is completed for all the primary outcome measures. The "anticipated" primary completion date is the date that the researchers think will be the primary completion date for the study.
March 1, 2026

Study Completion (Estimated)

Study Completion

The date on which the last participant in a clinical study was examined or received an intervention/treatment to collect final data for the primary outcome measures, secondary outcome measures, and adverse events (that is, the last participant's last visit). The "anticipated" study completion date is the date that the researchers think will be the study completion date.
March 1, 2026

Study Registration Dates

First Submitted

First Submitted

The date on which the study sponsor or investigator first submitted a study record to ClinicalTrials.gov. There is typically a delay of a few days between the first submitted date and the record's availability on ClinicalTrials.gov (the first posted date).
February 11, 2022

First Submitted That Met QC Criteria

First Submitted That Met QC Criteria

The date on which the study sponsor or investigator first submits a study record that is consistent with National Library of Medicine (NLM) quality control (QC) review criteria. The sponsor or investigator may need to revise and submit a study record one or more times before NLM's QC review criteria are met. It is the responsibility of the sponsor or investigator to ensure that the study record is consistent with the NLM QC review criteria.
February 23, 2022

First Posted (Actual)

First Posted

The date on which the study record was first available on ClinicalTrials.gov after National Library of Medicine (NLM) quality control (QC) review has concluded. There is typically a delay of a few days between the date the study sponsor or investigator submitted the study record and the first posted date.
March 4, 2022

Study Record Updates

Last Update Posted (Actual)

Last Update Posted

The most recent date on which changes to a study record were made available on ClinicalTrials.gov. There may be a delay between when the changes were submitted to ClinicalTrials.gov by the study's sponsor or investigator (the last update submitted date) and the last update posted date.
November 24, 2025

Last Update Submitted That Met QC Criteria

Last Update Submitted That Met QC Criteria

The most recent date on which the study sponsor or investigator submitted changes to a study record that are consistent with National Library of Medicine (NLM) quality control (QC) review criteria. It is the responsibility of the sponsor or investigator to ensure that the study record is consistent with the NLM QC review criteria.
November 19, 2025

Last Verified

Last Verified

The most recent date on which the study sponsor or investigator confirmed the information about a clinical study on ClinicalTrials.gov as accurate and current. If a study with a recruitment status of recruiting; not yet recruiting; or active, not recruiting has not been confirmed within the past 2 years, the study's recruitment status is shown as unknown.
November 1, 2025

More Information

Terms related to this study

Additional Relevant MeSH Terms

Other Study ID Numbers

Other Study ID Numbers

Identifiers or ID numbers other than the NCT number that are assigned to a clinical study by the study's sponsor, funders, or others. These numbers may include unique identifiers from other trial registries and National Institutes of Health grant numbers.
  • OP-1250-002

Plan for Individual participant data (IPD)

Plan to Share Individual Participant Data (IPD)?

NO

Drug and device information, study documents

Studies a U.S. FDA-regulated drug product

Yes

Studies a U.S. FDA-regulated device product

No

product manufactured in and exported from the U.S.

Yes

This information was retrieved directly from the website clinicaltrials.gov without any changes. If you have any requests to change, remove or update your study details, please contact register@clinicaltrials.gov. As soon as a change is implemented on clinicaltrials.gov, this will be updated automatically on our website as well.

Cookie Settings

We use cookies to ensure that we give you the best experience on our website. For more details carefully read our Privacy and Cookies Policy. ...>>>You can change your preferences or withdraw your consent at any time by deleting the cookies from your website or computer as described in the policy. Please accept it and choose your preferences by ticking the corresponding boxes in the "Manage Settings" section below. Please carefully read our Terms of Service before you proceed with using any part of this website.
«Manage Settings