Double-Blind, Placebo-Controlled, Randomized Clinical Trial Demonstrates Telomerase Activator TA-65 Decreases Immunosenescent CD8+CD28- T Cells in Humans

TA-65 is a small molecule telomerase activator extracted from Astragalus species. A previous observational study suggested that TA-65 decreased the number of immunosenescent cells in healthy subjects. Here we examined the impact of TA-65 in a much larger randomized, double-blind, and placebo-controlled study. This study aims to evaluate the effects of TA-65 on senescent CD8+CD28- T cells in healthy subjects. This was a randomized, double-blind, placebo-controlled, and multi-arm parallel trial in 500 healthy subjects. Subjects, clinical staff, and primary outcome assessors were blinded until the database lock. A total of 500 healthy volunteers were randomly allocated, 100 subjects each, into one of the five groups; placebo, TA-65 (100 Units) qd, TA-65 (250 Units) qd, TA-65 (500 Units) qd, or TA-65 (250 Units) b.i.d. Change in the immunosenescence biomarker after nine months was measured. The intention-to-treat analysis of the primary outcome measure included all the randomized subjects (n = 500). Per-protocol analysis of the primary outcome measured included 93% of the randomized subjects (n = 424). Multilevel analysis revealed a significant decrease in the CD8+CD28- T cells with TA-65 intervention compared to the placebo group (p