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Study to Examine Distribution of Aromatase Inhibitor and Ribociclib in ER+ HER2- Early Breast Cancer in Postmenopausal Women Scheduled for Surgery

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What is this study about?

This study is investigating the distribution of medications within breast cancer tumors that are estrogen receptor positive (ER+) and HER2 negative (HER2-). The treatment being studied includes an Aromatase Inhibitor and a CDK4/6 inhibitor called ribociclib. The purpose is to determine how these medications spread throughout different regions of breast cancer tumors in postmenopausal women who are scheduled for surgery.

The study involves patients taking the medications before their planned surgery. During this time, researchers will use various imaging techniques such as magnetic resonance imaging (MRI) and ultrasonography to examine the tumor. After surgery, the removed tumor tissue will be analyzed using mass spectrometry to measure the concentration of medications in different areas of the tumor.

Additionally, researchers will examine how the medications affect the immune system by studying immune cells in both the sentinel lymph node (the first lymph node to which cancer cells are likely to spread) and in the blood. They will also assess how effectively the medications work against the cancer by measuring changes in the tumor and specific markers of cell growth.

1 Initial Treatment Assignment

Once you join the study, you will be assigned to receive treatment with either an aromatase inhibitor (AI) alone or an AI combined with ribociclib (a CDK4/6 inhibitor) before your scheduled breast cancer surgery.

This study is for postmenopausal women with ER+ HER2- breast cancer (estrogen receptor positive, human epidermal growth factor receptor 2 negative) in early stages (stage I-IIa) with tumors between 1.5-5 cm.

2 Medication Regimen

Depending on your treatment assignment, you will take one of the following medication combinations daily:

Option 1: Anastrozole (1 mg film-coated tablet) taken once daily

Option 2: Letrozole (2.5 mg film-coated tablet) taken once daily

Option 3: Anastrozole (1 mg) plus Ribociclib (Kisqali 200 mg film-coated tablets) taken daily

Option 4: Letrozole (2.5 mg) plus Ribociclib (Kisqali 200 mg) taken daily

You will continue this treatment until your scheduled surgery date.

3 Baseline Imaging Tests

Before starting treatment, you will undergo imaging tests to assess your tumor:

Magnetic Resonance Imaging (MRI): A non-invasive imaging test that uses magnetic fields to create detailed images of your breast tumor.

Ultrasonography (US): An imaging technique that uses sound waves to create pictures of the inside of your breast.

4 Blood Samples

Blood samples will be collected at the beginning of the study and again before surgery.

These samples will be used to measure immune cell types and cytokines (proteins that affect immune system function) in your blood.

5 Follow-up Imaging

During the treatment period, you will have additional MRI and ultrasound scans to monitor changes in your tumor.

6 Surgery

You will undergo your planned breast cancer surgery as scheduled by your medical team.

During surgery, tissue samples will be collected from your tumor and sentinel lymph node (the first lymph node where cancer cells are likely to spread).

7 Tissue Analysis

After surgery, your tumor tissue will be analyzed to:

Measure the concentration of the medications in different regions of your tumor using mass spectrometry.

Examine the tumor tissue under a microscope (immunohistochemistry) to assess changes in cancer cells and the tumor environment.

Evaluate your response to treatment by measuring residual cancer burden (RCB) and Ki67 expression (a marker of cell growth).

8 Side Effect Monitoring

Throughout the study and for 30 days after surgery, you will be monitored for side effects from the medications, particularly ribociclib.

Any adverse events will be recorded according to standard criteria (CTCAE 5.0 – Common Terminology Criteria for Adverse Events).

Who Can Join the Study?

  • You must be a woman who is postmenopausal (no longer having menstrual periods) and at least 18 years old.
  • You must have been diagnosed with adenocarcinoma (a type of cancer) of the breast that is at clinical stage I-IIa (tumor size between 1.5-5 cm without spread to lymph nodes).
  • Your breast cancer must be ER+ (estrogen receptor positive, meaning your cancer cells grow in response to the hormone estrogen) with at least 10% of cells showing ER expression.
  • Your breast cancer must be HER2- (human epidermal growth factor receptor 2 negative, meaning your cancer cells don’t have high levels of this protein).
  • You must be scheduled for upfront surgery (surgery as the first treatment approach).
  • You must have good performance status with an ECOG score better than 2 (able to carry out all or most of your daily activities).
  • You must have good organ function.
  • You must be able to provide written informed consent and follow the study protocol.

Who Cannot Join the Study?

  • You cannot participate if you are not postmenopausal (meaning your menstrual periods have stopped completely for at least one year).
  • You cannot participate if your breast cancer is not ER+ HER2- type (this refers to specific markers on the cancer cells: estrogen receptor positive and human epidermal growth factor receptor 2 negative).
  • You cannot participate if you have already received treatment for your breast cancer, such as chemotherapy, hormonal therapy, or radiation therapy.
  • You cannot participate if you are not scheduled for surgery to remove your breast tumor.
  • You cannot participate if you have allergies or hypersensitivity to the study medications (aromatase inhibitors or ribociclib).
  • You cannot participate if you have certain heart conditions, including heart rhythm problems or a history of heart attacks.
  • You cannot participate if you have severe liver or kidney disease.
  • You cannot participate if you are taking medications that might interact with the study drugs.
  • You cannot participate if you are pregnant or breastfeeding.
  • You cannot participate if you have other serious medical conditions that might interfere with the study or put your health at risk.

Where you can join this trial?

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Other Sites

Site Name City Country Status
Amggpoorr Uen Amsterdam The Netherlands

Want to learn more about this study or check if you can participate? Contact us.

Trial status

Country Status Recruitment Start
The Netherlands The Netherlands
Not yet recruiting
01.11.2025

Trial locations

Investigated drugs:

Aromatase Inhibitor is a medication that lowers estrogen levels in the body. It works by blocking the enzyme aromatase, which helps convert other hormones into estrogen. This medication is commonly used to treat breast cancer that is sensitive to estrogen (ER+), as it can help slow or stop the growth of these cancer cells by reducing the amount of estrogen available to them.

Ribociclib (also known as a CDK4/6 inhibitor) is a medication that works by blocking specific proteins called cyclin-dependent kinases 4 and 6. These proteins play a role in cell division and growth. By inhibiting these proteins, ribociclib can help stop cancer cells from multiplying. It’s typically used in combination with hormone therapy to treat certain types of breast cancer.

Investigated diseases:

Estrogen Receptor-Positive, HER2-Negative Breast Cancer – A type of breast cancer characterized by the presence of estrogen receptors (ER+) and the absence of human epidermal growth factor receptor 2 (HER2-) on cancer cells. These cancer cells grow in response to the hormone estrogen. The cancer typically begins in the cells lining the milk ducts or lobules, gradually spreading into surrounding breast tissues. As it progresses, the cancer may invade nearby lymph nodes, particularly those in the axilla (armpit). ER+ HER2- breast cancer represents the most common subtype of breast cancer and tends to grow more slowly than some other types.

Trial ID:
2025-520530-32-00
Protocol code:
29973113
Trial Phase:
Therapeutic confirmatory (Phase III)

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