Cardioprotection Effect of Linagliptin

1\. Background and Rationale Breast cancer is one of the most common malignancies affecting women worldwide and represents a major health burden in Egypt. Anthracyclines, particularly doxorubicin, remain an important component of several breast cancer chemotherapy regimens. However, their clinical utility is limited by the potential development of anthracycline-induced cardiotoxicity. Doxorubicin-induced cardiac injury is multifactorial and involves oxidative stress, mitochondrial dysfunction, disturbances in myocardial energy metabolism, apoptosis, inflammation, and progressive myocardial structural damage. Cardiac injury may initially occur without symptoms or an obvious reduction in left ventricular ejection fraction (LVEF). Consequently, identification of early myocardial injury is important because intervention before clinically apparent heart failure may potentially reduce progression to overt cardiac dysfunction.

Inclusion Criteria: * 1\. Female patients aged ≥18 years. 2. Egyptian nationality. 3. Histologically confirmed breast cancer. 4. Planned treatment with a doxorubicin-containing chemotherapy regimen. 5. Expected cumulative doxorubicin dose of approximately ≥240 mg/m², or another prespecified protocol threshold. 6\. Baseline LVEF ≥53%. 7. Adequate baseline echocardiographic assessment. 8. Baseline cardiac troponin below the laboratory's predefined exclusion threshold. 9\. Ability to take oral medication. 10. Ability to provide written informed consent. 11. Willingness to comply with study visits, blood sampling and cardiac assessments. Exclusion Criteria: * 1\. Previous exposure to anthracyclines. 2. Known heart failure. 3. Baseline LVEF \