Protocols

Animal studies do not confirm that TB-500 directly reactivates dormant tumors in humans, but they raise a biologically credible concern. Preclinical data show that thymosin beta-4 — the endogenous peptide TB-500 mimics — upregulates VEGF, activates pro-invasive signaling in cancer cell lines, and is overexpressed in several human tumor types. No controlled human trial has tested this risk.

PT-141 (bremelanotide) carries a formal FDA contraindication in patients with known cardiovascular disease or uncontrolled hypertension. In controlled trials, the 1.75 mg subcutaneous dose transiently raised mean systolic blood pressure by approximately 3 mmHg and lowered heart rate by roughly 2 bpm — effects that resolve within 12 hours but pose disproportionate risk in patients with compromised cardiac reserve.