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Study of PF-07220060 and Fulvestrant for Adults with Advanced or Metastatic HR-positive, HER2-negative Breast Cancer After Previous Treatment

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What is this trial about?

A plain-language summary of the goals, design and what participants do

This clinical trial is focused on studying a type of breast cancer known as hormone receptor-positive, HER2-negative advanced or metastatic breast cancer. This type of cancer has spread beyond the breast and is not responsive to certain hormone therapies. The study will explore the effectiveness of a new treatment combination involving a study medicine called PF-07220060 and an existing medication called fulvestrant. Fulvestrant is a solution for injection that works by blocking the effects of estrogen, a hormone that can promote the growth of breast cancer cells.

The purpose of the study is to compare the new treatment combination to other therapies chosen by the study doctors. Participants will be randomly assigned to receive either the new treatment or one of the other therapies. The study will last for up to 24 months, during which participants will receive regular treatments and check-ups to monitor their health and the progress of their cancer. The study aims to see if the new treatment can help delay the progression of the disease.

Participants in the study will include adults over the age of 18 who have previously been treated with a type of medication known as a CDK 4/6 inhibitor, which is used to slow down the growth of cancer cells. The study will also look at how the new treatment affects overall survival, the response of the cancer to treatment, and the quality of life of participants. This research is important for finding new ways to manage and treat advanced breast cancer, offering hope for improved outcomes for patients in the future.

The research process

The trial runs in 5 steps – from screening to follow-up. Each step says what happens and what the team monitors.

  1. Step 1

    Joining the study

    Upon joining the study, eligibility is confirmed based on specific criteria, including age and medical history related to breast cancer.

    A tumor tissue sample is required for further analysis.

  2. Step 2

    Randomization

    Participants are randomly assigned to one of two groups: Arm A or Arm B.

    Arm A receives the study medication PF-07220060 in combination with fulvestrant.

    Arm B receives a treatment chosen by the investigator, which may include everolimus or exemestane.

  3. Step 3

    Treatment administration

    In Arm A, fulvestrant is administered as an intramuscular injection at a dose of 250 mg.

    PF-07220060 is taken orally, with the dosage determined by the study protocol.

    In Arm B, everolimus is taken orally as a 5 mg or 10 mg tablet, and exemestane is taken orally as a 25 mg coated tablet.

  4. Step 4

    Monitoring and assessments

    Regular monitoring is conducted to assess the progression of the disease and the response to treatment.

    Assessments include imaging tests and evaluations of overall health and quality of life.

  5. Step 5

    End of treatment

    The treatment continues until disease progression or unacceptable side effects occur.

    The study aims to evaluate progression-free survival and overall survival.

Who can join the trial?

8 criteria

  • Must be at least 18 years old, or the minimum age of consent according to local rules, at the time of screening.
  • Must have a confirmed diagnosis of breast cancer that has spread locally or to other parts of the body, and cannot be treated with surgery or radiation to cure it.
  • Must be able to provide a sample of the tumor tissue that has been preserved in a specific way called formalin-fixed, paraffin-embedded (FFPE).
  • Must have previously received a treatment called CDK4/6 inhibitor (CDK4/6i) along with a non-steroidal aromatase inhibitor (NSAI) in one of the following situations:
    • One previous treatment for advanced/metastatic breast cancer, which must include CDK4/6i plus NSAI.
    • Two previous treatments for advanced/metastatic breast cancer, one of which must include CDK4/6i plus NSAI, and the other must target specific genes or proteins like estrogen receptor 1 (ESR1), PIK3CA, AKT1, PTEN, or BRCA.
    • No previous treatments for advanced/metastatic breast cancer, but received CDK4/6i plus NSAI as the most recent therapy after initial treatment.
    • Must have either measurable disease or bone-only disease that cannot be measured, as defined by a specific guideline called RECIST v1.1.
    • Must have an Eastern Cooperative Oncology Group (ECOG) Performance Status of 0, 1, or 2, which is a scale used to assess how well a person can perform daily activities.

Who cannot join the trial?

12 criteria

  • Patients who have a different type of cancer than the one being studied.
  • Patients who are not within the specified age range for the study.
  • Patients who are not able to follow the study procedures or instructions.
  • Patients who have other serious health conditions that might interfere with the study.
  • Patients who are pregnant or breastfeeding.
  • Patients who have participated in another clinical trial recently.
  • Patients who are allergic to any of the study medications.
  • Patients who have a history of certain heart problems.
  • Patients who have uncontrolled infections.
  • Patients who have had another type of cancer within the last five years, except for certain skin cancers.
  • Patients who have a history of drug or alcohol abuse.
  • Patients who are unable to give informed consent, which means they cannot understand and agree to the study details.
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Investigated drugs

  • PF-07220060

    is an investigational medication being studied for its potential to treat advanced or metastatic breast cancer. It is being tested in combination with another medication to see if it can help slow down the progression of the disease in patients who have already received certain types of cancer treatments.

  • Fulvestrant

    is a medication used in the treatment of hormone receptor-positive breast cancer. It works by blocking the effects of estrogen in the body, which can help slow or stop the growth of cancer cells that need estrogen to grow. In this trial, it is used in combination with PF-07220060 to evaluate their combined effectiveness in treating breast cancer.

What is already known about the treatment

  • PF-07220060

    This medication is administered orally and is currently being studied in clinical trials for its effectiveness in treating hormone receptor-positive, HER2-negative advanced or metastatic breast cancer. It is in the experimental phase and not yet widely available in medical practice. The main therapeutic indication is for patients whose disease has progressed after prior CDK 4/6 inhibitor-based therapy. PF-07220060 works by targeting specific proteins involved in cell division, aiming to slow down or stop the growth of cancer cells. It is classified as a targeted cancer therapy.

  • Fulvestrant

    This medication is administered via intramuscular injection and is an established treatment in the medical field for hormone receptor-positive breast cancer. It is used primarily for patients with advanced or metastatic breast cancer, particularly after other hormone therapies have failed. Fulvestrant works by binding to estrogen receptors and degrading them, which helps to block the growth of cancer cells that rely on estrogen. It is classified as an estrogen receptor antagonist.

Investigated diseases

Hormone receptor-positive, HER2-negative advanced/metastatic breast cancer – This type of breast cancer is characterized by the presence of hormone receptors on the surface of cancer cells, which means the cancer cells grow in response to hormones like estrogen or progesterone. It is classified as HER2-negative, indicating that the cancer cells do not have an excess of the HER2 protein on their surfaces. This form of breast cancer can spread beyond the breast to other parts of the body, such as bones, liver, or lungs, which is referred to as metastatic. The progression of the disease involves the growth and spread of cancer cells, which can lead to various symptoms depending on the organs affected. The disease is often managed by targeting the hormone receptors to slow down or stop the growth of cancer cells.
Trial detailsLast updated 2 Oct 2026
Age18+ yearsPhasePhase IIITrial ID2023-506487-13-00Protocol codeC4391022Estimated enrolment500 patientsSponsorPfizer Inc.

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On this site, “treatment” means an investigational medicine being studied in a clinical trial. Its safety and efficacy for the use being studied have not yet been confirmed, some participants may receive a placebo or a comparator medicine, and taking part does not guarantee any health benefit. The decision to take part is made by the doctor at the research site. This site is for information only and does not replace medical advice.

This service is not affiliated with the European Commission, the EMA, or the official CTIS system. Most information comes from publicly available international clinical-trial registries, supplemented by data from academic sites, national regulators and commercial sponsors. On this site, “treatment” and “therapy” mean a medicine being tested in a clinical trial. Its safety and effectiveness in the use being studied are not yet confirmed, some participants may receive a placebo or a comparator, and taking part does not guarantee a health benefit. The doctor at the research site decides who can take part. This site provides information, not medical advice. Certain content and visual elements on this website have been generated or enhanced using artificial intelligence (AI).