RecruitingInterventionalPhase 3

An Interventional, Open-Label, Randomized, Multicenter, Phase 3 Study of PF-07248144 Plus Fulvestrant Compared to Investigator's Choice of Therapy in Adult Participants With Hormone Receptor-Positive, HER2-Negative Advanced/Metastatic Breast Cancer Whose Disease Progressed After Prior CDK4/6 Inhibitor-based Therapy

NCT ID: NCT07062965Sponsor: PfizerLast updated: 2026-05-06

Summary

The purpose of this study is to learn about the safety and effects of the study medicine PF-07248144 when given along with fulvestrant for the possible treatment of HR-positive, HER2-negative advanced or metastatic breast cancer. HR-positive breast cancer cells have proteins on their surface called receptors that bind to hormones like estrogen and progesterone (female sex hormones). These hormones can promote the growth of cancer cells. HER2-negative describes cells that have a small amount or none of a protein called HER2 on their surface. In normal cells, HER2 helps control cell growth. Cancer cells that are HER2-negative may grow more slowly and are less likely to recur (come back) or spread to other parts of the body than cancer cells that have a large amount of HER2 on their surface. Advanced cancer is a term that is often used to describe cancer that is unlikely to be cured. Metastatic cancer is the type where the cancer cells spread from one part of the body to another. This study is seeking for participants whose breast cancer has gotten worsen after receiving cyclin dependent kinase (CDK) 4/6 inhibitor-based therapy. Half of participants in this study will receive their usual study treatment, everolimus with endocrine therapy (either exemestane or fulvestrant) for HR-positive/HER2-negative advanced or metastatic breast cancer (A/mBC). The study doctor will discuss which hormone therapy is right for the participant before treatment begins. PF-07248144 is a tablet that will be taken by mouth at home every day in a 28-day cycle. Fulvestrant will be given as two injections (one injection in the buttock) at visits to the study clinic. Everolimus and exemestane are also tablets and will be taken by mouth at home every day in a 28-day cycle. The study will compare the experiences of people receiving PF-07248144 in combination with fulvestrant to those of the people who do not. This will help see if PF-07248144 in combination with fulvestrant is safe and effective.

Arms & interventions

DrugPF-07248144
KAT6 inhibitor
DrugFulvestrant
Endocrine therapy
DrugEverolimus
mTOR inhibitor
DrugExemestane
Endocrine therapy

Outcome measures

Primary

Progression Free Survival (PFS) as determined by blinded independent central review (BICR) per Response Evaluation Criteria in Solid Tumors (RECIST) v1.1
Time frame: From the date of randomization until disease progression or death due to any cause (up to approximately 2 years)

Secondary

Overall Survival (OS)
Time frame: From the date of randomization until death due to any cause (up to approximately 5 years).
Number of Participants with Objective Response (OR) by BICR
Time frame: From the date of randomization until disease progression or death due to any cause (up to approximately 2 years)
Duration of Response (DoR) as defined by BICR
Time frame: From the date of the first objective (PR or CR) response (every 8 weeks during the first 48 weeks and then every 12 week) up to approximately 2 years.
Number of Participants With Clinical Benefit Response (CBR) by BICR
Time frame: From randomization date (every 8 weeks during the first 48 weeks and then every 12 weeks) up to approximately 2 years.
Number or Patients with Adverse Events (AEs) by Type
Time frame: From screening until 28 days after the last dose, to approximately 5 years
Number or Patients with AEs by Incidence
Time frame: From screening until 28 days after the last dose, to approximately 5 years
Number or Patients with AEs by Seriousness
Time frame: From screening until 28 days after the last dose, to approximately 5 years
Number or Patients with AEs by relationship to study interventions
Time frame: From screening until 28 days after the last dose, to approximately 5 years
Number of Participants With Abnormal Electrocardiogram (ECG; Arm A and B)
Time frame: From screening until 28 days after the last dose, to approximately 5 years
Number of Participants With Increase From Baseline in Corrected QT (QTc) Interval (Arm A only)
Time frame: 0h pre-dose on Cycle 1 Day 1, Cycle 1 Day 15, Cycle 2 Day 1, and Cycle 3 Day 1; additional 4 hrs post dose on Cycle 1 Day 15 and Cycle 2 Day 1
Number of Participants With Laboratory Test Abnormalities
Time frame: From screening until 28 days after the last dose, to approximately 5 years
Ctrough of PF-07248144
Time frame: Cycle 1 (Day 1), Cycle 1 (Day 15), Cycle 2 (Day 1), and Cycles 3, 5, and 7 (Day 1) only. Each Cycle is 28 days

Eligibility criteria

Sex: AllAge: 18 Years and olderHealthy volunteers: No

Inclusion Criteria: * Confirmed diagnosis of HR-positive HER2-negative breast cancer with evidence of locally advanced or metastatic disease, which is not amenable to surgical resection or radiation therapy with curative intent. * Prior CDK4/6 inhibitor therapy in combination with endocrine therapy in advance metastatic setting or in adjuvant setting with documented progression during or within 12 months after the last dose of CDK4/6i. * Participants are eligible if they previously received CDK4/6i or ET as a monotherapy, or in combination for rechallenge therapy in the advance or metastatic setting; have received prior therapy targeting estrogen receptor 1 (ESR1) or breast cancer gene (BRCA)1/2. * Measurable disease evaluable per Response Evaluation Criterion in Solid Tumors (RECIST) v.1.1 or non-measurable bone-only disease * Eastern Cooperative Oncology Group (ECOG) Performance Status (PS) 0 or 1. Exclusion Criteria: * Documented detectable PIK3CA/AKT1/PTEN alterations in tissue * Received greater than two prior lines of systemic therapy in the advance or metastatic setting * Had received any prior chemotherapy, including antibody drug conjugates (ADCs), in advance or metastatic setting. Participants who have previously received chemotherapy in the (neo)adjuvant setting are not excluded from the study. * Any medical or psychiatric condition that may increase the risk of study participation or make the participant inappropriate for the study. * Renal impairment, hepatic dysfunction, or hematologic abnormalities.

Study locations (102)

Ironwood Cancer & Research Centers

Chandler, Arizona, 85224

Recruiting

Ironwood Cancer & Research Centers

Gilbert, Arizona, 85297

Recruiting

Ironwood Cancer & Research Centers

Glendale, Arizona, 85306

Recruiting

Ironwood Cancer & Research Centers

Goodyear, Arizona, 85395

Recruiting

Ironwood Cancer & Research Centers

Mesa, Arizona, 85202

Recruiting

Ironwood Cancer & Research Centers

Mesa, Arizona, 85206

Recruiting

Ironwood Cancer & Research Centers

Phoenix, Arizona, 85028

Recruiting

Ironwood Cancer & Research Centers

Scottsdale, Arizona, 85260

Recruiting

Ventura County Hematology Oncology Specialists

Camarillo, California, 93010

Not Yet Recruiting

Los Angeles Cancer Network - (Admin Only / Central IDS) - No Patients

Glendale, California, 91204

Not Yet Recruiting

Los Angeles Cancer Network - Good Samaritan

Los Angeles, California, 90017

Not Yet Recruiting

Los Angeles Hematology Oncology Medical Group

Los Angeles, California, 90017

Not Yet Recruiting

Rolling Oaks Radiology - Oxnard

Oxnard, California, 93030

Not Yet Recruiting

Ventura County Hematology Oncology Specialists

Oxnard, California, 93030

Not Yet Recruiting

Dr. Manoj Khatore, MD, FACC (Cardiology Practice)

Oxnard, California, 93036

Not Yet Recruiting

Ventura County Hematology Oncology Specialists

Ventura, California, 93003

Not Yet Recruiting