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NCT Number: NCT05266105

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

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).

Active, Not Recruiting

This study is active but is not currently recruiting participants.

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Key information

Conditions

Breast Cancer Breast Diseases Breast Neoplasms Neoplasms Neoplasms by Site Skin Diseases Skin and Connective Tissue Diseases

Age range

18 year and older

Sex eligibility

All sexes

Study type

Interventional

Phase

Phase 1

Primary location

Clinical Trial Site, Waratah, New South Wales, Australia

Loading trial locations.

Who can participate

Healthy volunteers accepted: No

Only the study team can determine whether someone qualifies for participation.

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

Treatment and study plan

Palazestrant

Drug

Complete Estrogen Receptor Antagonist

Other names: OP-1250

Palbociclib

Drug

Palbociclib is an approved CDK 4/6 Inhibitor drug

Other names: Ibrance®️

Primary outcomes

  1. Incidence of Dose Limiting Toxicities

    Time frame: From Cycle 1 Day 1 through C1 Day 28

  2. Characterization and Incidence in Adverse Events and Serious Adverse Events

    Time frame: From initial inform consent date through 30 days post last dose

  3. Plasma levels of OP-1250 and Palbociclib

    Time frame: Up to 9 months

Sponsors and collaborators

Lead sponsor

Olema Pharmaceuticals, Inc.

Industry

Collaborators

  • Pfizer

Registry information

Official study title

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

Important dates

Study start
2021
Primary completion
2026
Study completion
2026
First posted
Mar 4, 2022
Registry last updated
Nov 24, 2025

OpenTrials presents study information sourced from ClinicalTrials.gov. The official registry record should be consulted for the latest information.

View the official ClinicalTrials.gov record (opens in a new tab)

This listing is for discovery and informational purposes only. It is not medical advice, does not guarantee that a study is recruiting, and does not determine eligibility. Contact the study team and a qualified healthcare professional when considering participation.

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