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Study on Early Detection and Treatment of ER Positive HER2 Negative Breast Cancer Using Palbociclib, Fulvestrant, and Drug Combination for Patients with Molecular Relapse

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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 ER-positive HER2-negative breast cancer. The study aims to explore the effectiveness of a treatment combination of palbociclib and fulvestrant compared to standard hormone therapies. These standard therapies include medications like anastrozole, letrozole, exemestane, and tamoxifen. The trial will also involve tracking a specific type of DNA in the blood, known as circulating tumor DNA (ctDNA), to detect early signs of cancer returning.

The purpose of the study is to determine if the combination of palbociclib and fulvestrant can improve the time patients remain free from cancer recurrence compared to the standard hormone therapies. Participants will be monitored for the presence of ctDNA, which can indicate a molecular relapse, meaning the cancer might be returning at a microscopic level before it is visible on scans. If ctDNA is detected, patients will receive either the combination treatment or continue with their standard therapy.

Throughout the study, participants will undergo regular blood tests to check for ctDNA and assess their response to the treatment. The study will last for a maximum of 24 months, during which the safety and tolerability of the treatments will also be evaluated. The goal is to find the most effective way to prevent the return of breast cancer in patients who have already undergone initial treatment.

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 trial

    Upon joining the trial, you will provide written informed consent to participate. This includes agreeing to donate tissue and blood samples for research purposes.

  2. Step 2

    Surveillance phase

    During this phase, regular blood tests will be conducted to detect circulating tumor DNA (ctDNA). This helps in monitoring for any signs of cancer returning at a molecular level.

    You will continue your current standard endocrine therapy, which may include medications such as letrozole, anastrozole, exemestane, or tamoxifen. These are taken orally as prescribed by your doctor.

  3. Step 3

    Treatment phase

    If ctDNA is detected, you may be randomized to receive additional treatment with palbociclib and fulvestrant. Palbociclib is taken orally, while fulvestrant is administered through an intramuscular injection.

    The goal of this phase is to assess whether the combination of palbociclib and fulvestrant improves the time you remain free from cancer recurrence compared to standard endocrine therapy alone.

  4. Step 4

    Ongoing monitoring

    Throughout the trial, your health and response to treatment will be closely monitored. This includes regular check-ups and assessments to ensure your safety and well-being.

    You will be asked to report any side effects or changes in your health to the trial team promptly.

  5. Step 5

    End of trial

    The trial is expected to continue until December 31, 2030. Your participation may end earlier if you complete the treatment phase or if you choose to withdraw from the study.

    At the end of the trial, you will receive information about the overall findings and any implications for your future care.

Who can join the trial?

11 criteria

  • Provide written informed consent to participate in the trial and to donate tissue and blood samples.
  • Be willing to use an adequate method of contraception if you are of reproductive potential. This applies for the first three years of the trial if you are assigned to standard endocrine therapy, and for two years after the last dose of fulvestrant if assigned to fulvestrant and palbociclib. Note: Abstinence is acceptable if it is your usual lifestyle and preferred method.
  • Be willing to have frequent blood tests.
  • Be a male or female aged 18 years or older.
  • Have an ECOG performance status of 0, 1, or 2. This is a scale used to assess how your disease affects your daily living abilities.
  • Have a diagnosis of ER positive HER2 negative breast cancer confirmed by a local laboratory. This means your cancer cells have certain hormone receptors and do not have excess HER2 protein.
  • Have high risk early stage breast cancer based on specific criteria, such as tumor size or lymph node involvement, as determined by your doctor.
  • Have available tissue from one archival tumor tissue sample, which could be from a diagnostic biopsy, primary surgery, or residual disease post-treatment.
  • Have no evidence of macroscopic distant metastatic disease or incurable locally advanced disease on scans since your initial diagnosis. This means the cancer has not spread to distant parts of the body.
  • Be receiving standard endocrine therapy with specific medications for at least 6 months and no more than 7 years, with an additional three years of therapy planned. This includes medications like aromatase inhibitors or tamoxifen, and possibly GnRH analogues for pre- or peri-menopausal patients.
  • Have had surgery that achieved clear margins, meaning no cancer cells are seen at the outer edge of the tissue that was removed.

Who cannot join the trial?

10 criteria

  • Patients who do not have ER positive HER2 negative breast cancer cannot participate. This means the cancer must have certain characteristics related to hormone receptors and proteins.
  • Patients who are not within the specified age range cannot participate. The study is open to certain age groups only.
  • Patients who are not willing or able to follow the study procedures cannot participate.
  • Patients who have other medical conditions that might interfere with the study cannot participate.
  • Patients who are pregnant or breastfeeding cannot participate.
  • Patients who are currently participating in another clinical trial cannot participate.
  • Patients who have had a different type of cancer in the past, unless it was treated and cured, cannot participate.
  • Patients who have allergies or reactions to the study medications cannot participate.
  • Patients who have certain heart conditions cannot participate.
  • Patients who have severe liver or kidney problems cannot participate.
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Investigated drugs

  • Palbociclib

    is a medication used in this trial to help treat breast cancer. It works by blocking certain proteins in cancer cells, which can slow down or stop the growth of these cells. In this study, it is being tested to see if it can help prevent the cancer from coming back when used together with another medication called fulvestrant.

  • Fulvestrant

    is another medication used in this trial for treating breast cancer. It works by blocking the effects of estrogen, a hormone that can help some breast cancers grow. By blocking estrogen, fulvestrant can help slow down or stop the growth of cancer cells. In this study, it is being used alongside palbociclib to see if this combination is more effective than standard treatments in preventing cancer from returning.

What is already known about the treatment

  • Palbociclib

    Palbociclib is administered orally in the form of capsules. It is currently used in the treatment of ER positive HER2 negative breast cancer, as supported by medical literature. The main therapeutic indication for palbociclib is to improve relapse-free survival in patients with this type of breast cancer. At the molecular level, palbociclib works by inhibiting certain proteins called cyclin-dependent kinases, which are involved in cell division, thereby slowing down the growth of cancer cells. It is classified as a CDK4/6 inhibitor in pharmacology.

  • Fulvestrant

    Fulvestrant is administered via intramuscular injection. It is used in the treatment of ER positive HER2 negative breast cancer, as recognized in medical literature. The primary therapeutic indication for fulvestrant is to improve relapse-free survival in patients with this type of breast cancer. Fulvestrant works by binding to estrogen receptors on cancer cells, blocking the effects of estrogen, and leading to the degradation of these receptors, which helps slow down the growth of cancer cells. It is classified as an estrogen receptor antagonist in pharmacology.

Investigated diseases

Estrogen Receptor Positive, Human Epidermal Growth Factor Receptor 2 Negative Breast Cancer – This type of breast cancer is characterized by the presence of estrogen receptors on the surface of the cancer cells, which means the cancer cells may receive signals from estrogen that could promote their growth. It is also negative for the human epidermal growth factor receptor 2 (HER2), indicating that the cancer cells do not have an excess of the HER2 protein on their surfaces. The progression of this cancer can involve the growth and spread of cancer cells within the breast and potentially to other parts of the body. The disease may initially be localized but can become invasive, affecting nearby tissues and lymph nodes. Over time, if not managed, it can lead to distant metastasis, where cancer cells spread to other organs. The progression is often monitored through various tests, including those that detect circulating tumor DNA.
Trial detailsLast updated 7 Oct 2026
Age18+ yearsPhasePhase IITrial ID2024-517414-15-00Protocol codeCCR5316Estimated enrolment1 100 patientsSponsorThe Royal Marsden NHS Foundation Trust

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