TB-500 (Thymosin Beta 4 17-23 Fragment) for Cardiovascular Biomarkers in Stable ASCVD

Inclusion Criteria: * Age 40-75 years, able to provide written informed consent. * Documented stable ASCVD (e.g., prior myocardial infarction \>6 months ago, prior coronary revascularization, stable angina with objective evidence of ischemia, or symptomatic peripheral artery disease). * On stable guideline-directed medical therapy (e.g., statin and antiplatelet therapy unless contraindicated) for at least 8 weeks before screening. * Resting systolic blood pressure \<160 mmHg and diastolic blood pressure \<100 mmHg (with or without therapy). * Able and willing to comply with study visits and procedures. Exclusion Criteria: * Acute coronary syndrome, stroke/transient ischemic attack, or coronary revascularization within 6 months before screening. * New York Heart Association (NYHA) class III-IV heart failure or left ventricular ejection fraction \<35%. * Clinically significant arrhythmia requiring recent hospitalization or unstable antiarrhythmic therapy. * Severe renal impairment (eGFR \<30 mL/min/1.73 m\^2) or end-stage renal disease. * Clinically significant hepatic impairment (e.g., Child-Pugh class B/C) or ALT/AST \>3x upper limit of normal at screening. * Active malignancy requiring systemic therapy (except adequately treated non-melanoma skin cancer) within the past 2 years. * Known autoimmune disease requiring systemic immunosuppression, or use of chronic systemic corticosteroids above physiologic replacement. * Pregnant or breastfeeding, or unwilling to use effective contraception during the study (if of childbearing potential). * Known hypersensitivity to peptide therapeutics or study formulation components. * Participation in another interventional clinical study or receipt of an investigational product within 30 days (or 5 half-lives, whichever is longer) prior to screening.