Tucidinostat Combined With Metronomic Capecitabine and Endocrine Therapy for Advanced HR-positive, HER2-negative Breast Cancer After CDK4/6 Inhibitor.

Exclusion Criteria

• •1. Known hypersensitivity to any formulation component of the study drug;
• •2. patients with previous severe, unexpected reactions to fluoropyrimidines or known hypersensitivity to fluoropyrimidines;
• •3. Patients with complete deficiency of dihydropyrimidine dehydrogenase (DPD) activity;
• •4. Visceral crisis;
• •5. Previously received treatment with histone deacetylase inhibitors or fluoropyrimidine drugs such as capecitabine;
• •6. Received chemotherapy, targeted therapy, Chinese herbal medicine with anti-tumor indications, or immunomodulatory drugs (including thymosin, interferon, interleukin, etc.) within 4 weeks before enrollment, or still within 5 half-lives of such drugs;
• •7. Received palliative radiotherapy for local lesions within 4 weeks before enrollment;
• •8. Patients with gastrointestinal perforation, fistula, abdominal abscess, gastrointestinal ulcer or active diverticulosis before enrollment;
• •9. Significant malnutrition (weight loss \> 5% in the past 1 month or \> 15% in the past 3 months, or food intake decreased by 1/2 or more in the past week), or still need to rely on intravenous nutritional support during the screening period;
• •10. Toxicities that did not recover to National Cancer Institute Common Adverse Event Terminology Version 5.0 (NCICTCAEv5.0) grade 0 or 1 toxicity from prior antineoplastic therapy prior to the first dose of study treatment(alopecia, grade 2 fatigue, grade 2 anemia, non-clinically critical and asymptomatic laboratory abnormalities can be enrolled);
• •11. Patients with currently symptomatic brain or meningeal metastasis;
• •12. Received immunosuppressive drugs within 4 weeks before enrollment, excluding nasal spray, inhalation or other local glucocorticoids or physiological doses systemic glucocorticoids (no more than 10 mg/day of prednisone or other glucocorticoids at an equivalent dose), or use of glucocorticoids for the prevention of contrast medium allergy;
• •13. The patient has any active autoimmune disease or has history of immune disorders (including but not limited to: interstitial pneumonia, uveitis, enteritis, hepatitis, hypophysitis, nephritis, hyperthyroidism, hypothyroidism; patients with vitiligo or complete remission of asthma in childhood without any intervention in adulthood can be included; those with asthma that require medical intervention with bronchodilators are not included);
• •14. Patients with active pulmonary tuberculosis who are receiving anti-tuberculosis treatment or have received anti-tuberculosis treatment within 1 year before screening;
• •15. Complications requiring long-term use of immunosuppressive drugs, or systemic or topical use of corticosteroids with immunosuppressive doses;
• •16. Received any anti-infection vaccine (such as influenza vaccine, chickenpox vaccine, etc.) within 4 weeks before enrollment;
• •17. Received major surgery (craniotomy, thoracotomy or laparotomy) within 4 weeks before enrollment or is expected to undergo major surgery during the study treatment period; received exploratory laparoscopic surgery within 2 weeks prior to enrollment;received central venous catheterization within 7 days prior to enrollment;
• •18. Concurrent participation in another interventional clinical study, unless participating in an observational (non-interventional) clinical study or in the safety follow-up of an interventional study Stage;
• •19. Known acute or chronic active hepatitis B (HBsAg positive and HBV DNA virus Load ≥ULN or ≥10\^3 copies/mL) or acute or chronic active hepatitis C (HCV antibody positive and HCV RNA positive);
• •20. Severe heart disease or discomfort, including but not limited to the following diseases: 1) Diagnosed history of heart failure or systolic dysfunction (LVEF\<50%); 2) arrhythmias requiring medical treatment or clinically significant; 3) high-risk uncontrolled arrhythmias, such as atrial tachycardia, resting heart rate \> 100 bpm, significant ventricular arrhythmia (such as ventricular tachycardia) or higher-grade AV block (ie Mobitz II second-degree AV block or third-degree AV block); 4) Angina pectoris; 5 ) Clinically significant valvular heart disease; 6) ECG shows transmural myocardial infarction; 7) Any other heart disease judged by the investigator to be inappropriate to participate in this trial, etc.;
• •21. Inability to swallow, bowel obstruction, or other factors that interfere with drug taking and absorption;
• •22. A history of immunodeficiency, including HIV test positive, or other acquired or congenital immunodeficiency diseases, or a history of organ transplantation;
• •23. Pregnant, lactating female patients, female patients of childbearing potential with a positive baseline pregnancy test, or patients of childbearing age who are unwilling to use effective contraception throughout the trial and within 6 months after the last study drug;
• •24. Serious concomitant disease or other comorbidities that would interfere with planned treatment;
• •25. Any other conditions deemed inappropriate by the investigator to participate in this study.