NCT05266105

Brief Summary

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).

Trial Health

55
Monitor

Trial Health Score

Automated assessment based on enrollment pace, timeline, and geographic reach

Trial has exceeded expected completion date
Enrollment
60

participants targeted

Target at P50-P75 for phase_1 breast-cancer

Timeline
Completed

Started Dec 2021

Typical duration for phase_1 breast-cancer

Geographic Reach
1 country

8 active sites

Status
active not recruiting

Health score is calculated from publicly available data and should be used for screening purposes only.

Trial Relationships

Click on a node to explore related trials.

Study Timeline

Key milestones and dates

Study Start

First participant enrolled

December 10, 2021

Completed
2 months until next milestone

First Submitted

Initial submission to the registry

February 11, 2022

Completed
21 days until next milestone

First Posted

Study publicly available on registry

March 4, 2022

Completed
4 years until next milestone

Primary Completion

Last participant's last visit for primary outcome

March 1, 2026

Completed
Same day until next milestone

Study Completion

Last participant's last visit for all outcomes

March 1, 2026

Completed
Last Updated

November 24, 2025

Status Verified

November 1, 2025

Enrollment Period

4.2 years

First QC Date

February 11, 2022

Last Update Submit

November 19, 2025

Conditions

Breast Cancer

Outcome Measures

Primary Outcomes (3)

  • Incidence of Dose Limiting Toxicities

    From Cycle 1 Day 1 through C1 Day 28

  • Characterization and Incidence in Adverse Events and Serious Adverse Events

    From initial inform consent date through 30 days post last dose

  • Plasma levels of OP-1250 and Palbociclib

    Up to 9 months

Study Arms (2)

Dose Escalation

EXPERIMENTAL

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: PalazestrantDrug: Palbociclib

Dose Expansion

EXPERIMENTAL

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: PalazestrantDrug: Palbociclib

Interventions

PalazestrantDRUG

Complete Estrogen Receptor Antagonist

Also known as: OP-1250
Dose EscalationDose Expansion
PalbociclibDRUG

Palbociclib is an approved CDK 4/6 Inhibitor drug

Also known as: Ibrance®️
Dose EscalationDose Expansion

Eligibility Criteria

Age18 Years+
Sexall
Healthy VolunteersNo
Age GroupsAdult (18-64), Older Adult (65+)

You may qualify if:

  • 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

You may not qualify if:

  • 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

Contact the study team to confirm eligibility.

Sponsors & Collaborators

Study Sites (8)

Clinical Trial Site

Waratah, New South Wales, 2298, Australia

Location

Clinical Trial Site

Westmead, New South Wales, 2145, Australia

Location

Clinical Trial Site

South Brisbane, Queensland, 4101, Australia

Location

Clinical Trial Site

Southport, Queensland, 4215, Australia

Location

Clinical Trial Site

Clayton, Victoria, 3168, Australia

Location

Clinical Trial Site

Frankston, Victoria, 3199, Australia

Location

Clinical Trial Site

Geelong, Victoria, 3220, Australia

Location

Clinical Trial Site

Nedlands, Western Australia, 6009, Australia

Location

MeSH Terms

Conditions

Breast Neoplasms

Interventions

palbociclib

Condition Hierarchy (Ancestors)

Neoplasms by SiteNeoplasmsBreast DiseasesSkin DiseasesSkin and Connective Tissue Diseases

Study Officials

  • Sue Johnson

    Olema Pharmaceuticals, Inc.

    STUDY DIRECTOR

Study Design

Study Type
interventional
Phase
phase 1
Allocation
NON RANDOMIZED
Masking
NONE
Purpose
TREATMENT
Intervention Model
SEQUENTIAL
Sponsor Type
INDUSTRY
Responsible Party
SPONSOR

Study Record Dates

First Submitted

February 11, 2022

First Posted

March 4, 2022

Study Start

December 10, 2021

Primary Completion

March 1, 2026

Study Completion

March 1, 2026

Last Updated

November 24, 2025

Record last verified: 2025-11

Data Sharing

IPD Sharing
Will not share

Locations

AU(8)