This clinical trial focuses on treating early breast cancer that is hormone receptor-positive and HER2-negative. The study evaluates the effectiveness and safety of using ribociclib (also known as LEE011) in combination with hormone therapy. The hormone therapy medications used in the study include anastrozole, letrozole, and goserelin.
The main purpose of this study is to determine if adding ribociclib to standard hormone therapy improves outcomes for patients with early breast cancer compared to hormone therapy alone. Ribociclib is given as a tablet that is taken by mouth, while goserelin is given as an injection under the skin. Anastrozole and letrozole are also taken as tablets.
During the study, patients will receive either the combination of ribociclib with hormone therapy or hormone therapy by itself. The treatment continues for up to 5 years, and patients will have regular check-ups to monitor their health. The study team will track how long patients remain free from cancer returning and assess the overall safety of the treatment combination.
1Initial medical assessment
Your medical condition will be confirmed as hormone receptor-positive, HER2-negative early breast cancer
Basic health tests will be performed including blood tests, heart function (ECG), and kidney function assessment
2Treatment assignment
You will be randomly assigned to one of two treatment groups
Group 1: endocrine therapy alone
Group 2: ribociclib plus endocrine therapy
3Treatment period
The treatment will continue for 5 years from the start date
Depending on your group, you will receive:
– Endocrine therapy: oral medications (anastrozole or letrozole)
– If applicable, goserelin will be given as an injection under the skin
– If assigned, ribociclib will be taken by mouth
4Regular monitoring
Regular health checks will include:
Blood tests to monitor cell counts and organ function
Heart monitoring with ECG
Physical examinations
Quality of life assessments
5Follow-up period
The study will continue until April 2026
Regular check-ups will monitor your health status
Assessment of how well the treatment is working
Monitoring for any side effects
Who Can Join the Study?
Must be at least 18 years old
Must sign an informed consent form before any study procedures
Must have completed radiation therapy (if required) before screening
Must be able to receive hormone therapy for at least 5 years
Must have good physical functioning status (ECOG 0 or 1, meaning able to perform daily activities)
Must have adequate blood test results, including:
Normal white blood cell counts
Normal platelet levels
Adequate hemoglobin levels
Normal kidney function
Normal liver function
Must have normal heart rhythm on ECG test
Must be willing to attend all scheduled visits and follow study procedures
Women who can become pregnant must have a negative pregnancy test and use effective birth control methods during the study
Must have confirmed breast cancer that is:
Hormone receptor-positive (responds to hormones)
HER2-negative (specific type of breast cancer)
Completely removed by surgery with clear margins
At specific disease stages (Stage IIA, IIB, or III) with certain risk factors
Must have completed chemotherapy (if required) before screening
Must have tumor tissue available for laboratory testing (except for patients in China)
Who Cannot Join the Study?
Previous treatment with CDK4/6 inhibitors (drugs that block specific proteins involved in cell growth)
Presence of metastatic disease (cancer that has spread to other parts of the body)
History of other malignancies within the past 5 years, except for adequately treated non-melanoma skin cancer or carcinoma in situ
Severe heart conditions including:
Uncontrolled high blood pressure
Heart attack within past 6 months
Unstable heart rhythm problems
Severe liver problems or abnormal liver function tests
Known hypersensitivity (allergic reaction) to the study medications
Pregnant or breastfeeding women
Participation in another clinical trial within 30 days before starting this study
Any condition that would make it unsafe for the patient to participate in the study, as determined by the study doctor
Unable to swallow oral medications
Major surgery within 14 days before starting the study treatment
Ribociclib
A medication used in combination with endocrine therapy for treating breast cancer. It belongs to a class of drugs called CDK4/6 inhibitors that help stop cancer cells from growing and dividing. This medication is taken orally and works by blocking specific proteins that promote cancer cell growth.
Endocrine Therapy (ET)
A treatment that blocks or lowers the amount of hormones in the body to stop or slow down the growth of hormone receptor-positive breast cancer. This therapy can include different types of hormone-blocking medications that either lower estrogen levels or prevent estrogen from attaching to cancer cells.
Hormone Receptor-Positive Breast Cancer – A type of breast cancer where cancer cells grow in response to hormones estrogen and progesterone. The cancer cells have proteins called hormone receptors that become activated when hormones attach to them. This disease typically develops in the breast tissue and can spread to nearby lymph nodes. The cancer cells display specific receptors on their surface that respond to natural hormones in the body. This condition represents the most common form of breast cancer.
HER2-Negative Breast Cancer – A form of breast cancer where the cancer cells do not have high amounts of a protein called HER2 on their surface. This cancer tends to grow more slowly than HER2-positive cancers. The disease develops when breast cells begin to divide uncontrollably without elevated levels of the HER2 protein. This type of breast cancer typically responds differently to treatments compared to HER2-positive cases.
Early Breast Cancer – A stage of breast cancer where the disease is contained within the breast or has only spread to nearby lymph nodes. At this stage, the cancer is localized and has not spread to distant parts of the body. The disease is typically discovered during early screening or when a small lump is detected. This represents the initial phase of breast cancer development.
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