Study on Lenvatinib, Pembrolizumab, and Fulvestrant for Breast Cancer

Inclusion Criteria

• Adults aged 18 or older with advanced breast cancer that cannot be surgically removed.
• Men and premenopausal women must be on hormone therapy for at least four weeks before starting the trial and continue it during the study.
• Diagnosed with ER+ (estrogen receptor positive) and HER2- (human epidermal growth factor receptor 2 negative) breast cancer.
• Cancer has progressed after at least one hormone therapy combined with a CDK 4/6 inhibitor.
• No more than two previous chemotherapy treatments for metastatic cancer.
• Stable brain metastases that have not worsened for at least four weeks.
• Life expectancy of at least 12 weeks.
• A new biopsy of the tumor is needed before starting the study, unless previous samples are available.
• Must have measurable disease based on specific criteria.
• Good overall health with a performance status score of 0 or 1.
• Blood pressure must be controlled, with or without medication.
• Adequate organ function based on lab tests.
• Women must not be pregnant or breastfeeding and must use effective birth control during the study and for a specified time after.
• Men must agree to use contraception or be abstinent during the study and for a short period after.
• Participants with hepatitis B or C must have controlled viral loads.
• Specific blood and organ function levels must be met.

Exclusion Criteria

• Previous treatment with certain immune therapies or lenvatinib.
• Recent cancer treatments or participation in other clinical trials.
• Active infections or other serious medical conditions.
• Known additional cancers requiring treatment in the past three years.
• Active brain metastases or certain lung diseases.
• Pregnant or breastfeeding women.
• History of severe allergic reactions to study drugs.
• Significant heart or blood vessel problems.
• Active autoimmune diseases requiring treatment in the past two years.
• Major surgery within the past three weeks.
• Certain kidney or liver function issues.