Skip to content
Clinical Trials – home

Rare diseases

Investigational molecules

Locations

Our offerNewsroom

Recruiting

Study on Stopping CDK4/6 Inhibitors in Patients with Metastatic HR Positive, HER2 Negative Breast Cancer Using Abemaciclib, Letrozole, and Fulvestrant

Verified siteRegistered drugNo placebo
Clinical Trials Concierge

Prefer not to search? Our Concierge searches the trials for you.

What is this trial about?

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

This clinical trial is focused on studying the effects of stopping certain medications in patients with metastatic HR-positive, HER2-negative breast cancer. This type of breast cancer is characterized by the presence of hormone receptors (HR) and the absence of a protein called HER2. The study involves medications known as CDK4/6 inhibitors, which include abemaciclib, ribociclib, and palbociclib. These medications are used in combination with endocrine therapy, which includes drugs like letrozole, fulvestrant, exemestane, and anastrozole. The purpose of the study is to evaluate whether stopping CDK4/6 inhibitors after a prolonged period of treatment can maintain disease stability in patients who have shown at least stable disease for 12 months.

Participants in the study will be randomly assigned to either continue or discontinue the CDK4/6 inhibitors while continuing with endocrine therapy. The study will monitor the patients over a period to see if the cancer remains stable without the CDK4/6 inhibitors. The main focus is to observe the progression-free survival rate, which means the length of time during and after the treatment that the patient lives with the disease without it getting worse. This will be assessed through imaging tests to check for any signs of cancer progression.

The trial aims to provide insights into the long-term management of metastatic HR-positive, HER2-negative breast cancer by understanding the effects of discontinuing CDK4/6 inhibitors. This could potentially lead to new strategies for maintaining disease control while minimizing medication use. The study is expected to run until 2028, with recruitment starting in late 2023.

The research process

The trial runs in 4 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, the patient must have given written informed consent and meet specific criteria, such as being postmenopausal, at least 18 years old, and having a confirmed diagnosis of metastatic HR positive, HER2 negative breast cancer.

    The patient must have been treated with a combination of a CDK4/6 inhibitor and endocrine therapy for at least 12 months, achieving disease control as assessed by the treating physician.

  2. Step 2

    Treatment phase

    During the treatment phase, the patient will continue to receive endocrine therapy. The specific medications involved in the study include abemaciclib, letrozole, fulvestrant, ribociclib, exemestane, anastrozole, and palbociclib.

    The medications are administered either orally or intramuscularly, depending on the specific drug. The frequency and dosage will be determined by the study protocol and the treating physician.

  3. Step 3

    Monitoring and assessment

    Throughout the study, the patient's health and response to treatment will be regularly monitored through radiologic imaging assessments to evaluate disease progression.

    The primary goal is to assess the progression-free survival rate 12 months after randomization, which means the proportion of patients who are alive and without disease progression at that time.

  4. Step 4

    End of study

    The study is estimated to conclude by May 15, 2028. At the end of the study, the collected data will be analyzed to determine the effectiveness of discontinuing CDK4/6 inhibitors while continuing endocrine therapy in maintaining disease control.

Who can join the trial?

9 criteria

  • The patient must be a female who has given written informed consent, meaning she agrees to participate in the study after being fully informed about it.
  • The patient must be considered postmenopausal, which means she has stopped having menstrual periods, usually due to age.
  • The patient must be at least 18 years old at the time of signing the written informed consent.
  • The patient must have been diagnosed with metastatic adenocarcinoma of the breast, which is a type of breast cancer that has spread to other parts of the body.
  • The patient must have a confirmed diagnosis of estrogen receptor positive (ER+) and HER2 negative (HER2-) disease. This means the cancer grows in response to estrogen but does not have high levels of a protein called HER2.
  • The patient must not have any curative treatment options available through surgery or radiotherapy, meaning these treatments cannot completely cure the cancer.
  • The patient must have been treated with a CDK4/6 inhibitor (a type of cancer medication) plus endocrine therapy (hormone therapy) for at least 12 months, with the disease being controlled (either completely gone, partially gone, or stable) as determined by the doctor before starting the study treatment.
  • The patient must have a preserved performance status of ECOG ≤ 2, which means she is able to carry out all self-care activities and is up and about more than 50% of waking hours.
  • The patient must have adequate bone marrow, renal (kidney), and hepatic (liver) function, meaning these organs are working well enough to participate in the study.

Who cannot join the trial?

5 criteria

  • Patients who do not have metastatic HR positive, HER2 negative breast cancer cannot participate. This means the cancer must have spread to other parts of the body, be hormone receptor positive (HR positive), and not have too much of a protein called HER2.
  • Patients who have not been on a combination treatment for at least 12 months cannot participate. This means they must have been receiving a specific type of treatment for at least a year.
  • Patients who do not have at least stable disease after the treatment period cannot participate. Stable disease means the cancer has not gotten worse.
  • Only female patients can participate. Male patients are not eligible.
  • Patients who are considered part of a vulnerable population cannot participate. This means people who might need special protection or care are not included.
Clinical Trials Concierge

Prefer not to search? Our Concierge searches the trials for you.

Tell us about your condition – we search every trial in Europe and connect you with the right site.

We usually reply within a few days

Verified sites

All sites with verified contact details – recruitment status may not be available; ask directly

Trial locations

Where you can join this trial

Countries are shaded by recruitment status. Click a recruiting country to ask about joining there.

Recruiting
Not finding your country?

Not sure what to do next?

Joining a clinical trial can seem overwhelming. We guide you step by step, so you know exactly what to expect and how we support you through the process.

See the full process and FAQ

Investigated drugs

  • CDK4/6 Inhibitors

    are medications used to treat certain types of breast cancer. They work by blocking proteins called CDK4 and CDK6, which are involved in cell division. By inhibiting these proteins, the medications help to slow down or stop the growth of cancer cells. In this trial, the focus is on patients who have been using these inhibitors for a prolonged period and are now being evaluated for the effects of discontinuing them.

  • Endocrine Therapy

    is a treatment that adds, blocks, or removes hormones. For breast cancer, it often involves medications that block the effects of estrogen, a hormone that can promote the growth of cancer cells. In this trial, patients continue to receive endocrine therapy even after stopping the CDK4/6 inhibitors, to help maintain disease control.

What is already known about the treatment

CDK4/6 Inhibitors – These medications are typically administered orally in the form of tablets. They are currently well-established in medical practice and literature for treating certain types of breast cancer. The main therapeutic indication is for metastatic hormone receptor-positive, HER2-negative breast cancer. At the molecular level, CDK4/6 inhibitors work by blocking specific proteins called cyclin-dependent kinases 4 and 6, which are involved in cell division, thereby slowing down the growth of cancer cells. They belong to the pharmacological class of targeted cancer therapies.

Investigated diseases

Metastatic Hormone Receptor Positive, HER2 Negative 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 grows 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. The term "metastatic" refers to cancer that has spread beyond the breast to other parts of the body. This disease often progresses slowly, with cancer cells spreading to bones, liver, lungs, or brain. Patients may experience symptoms related to the areas where the cancer has spread, such as bone pain or difficulty breathing. The progression of the disease can vary widely among individuals, with some experiencing long periods of stability.
Trial detailsLast updated 2 Oct 2026
Age18+ yearsPhasePhase IITrial ID2023-504141-31-00Protocol codeDISCUSSEstimated enrolment120 patientsSponsorFrankfurter Institut Fuer Klinische Krebsforschung IKF GmbH

sourced from the EU Clinical Trials Register and site verification

Want to learn more about this trial or check if you can participate?

Clinical Trials Concierge

Prefer not to search? Our Concierge searches the trials for you.

Tell us about your condition – we search every trial in Europe and connect you with the right site.