Scientists made a version of thymosin‑alpha‑1 that’s attached to an antibody fragment, which makes it stay in the body longer and work better at slowing breast‑cancer growth in mice. It also boosted immune cells and signaling molecules that fight tumors. This is an early‑stage lab result, not a ready‑to‑use treatment for people.

Thymosin alpha1 (Tα1) is a multifunctional polypeptide involved in immunoregulation, which universally exists in various organs. The clinical application, however, is limited because of its short half-life. The Fc domain of human IgG has functional properties, improving the affinity and serum half-life. In this study, we fused Tα1 to Fc domain of human IgG1 for generation of a novel long-acting fusion protein, termed Tα1-Fc. Tα1-Fc was expressed, purified, and identified. The results showed that Tα1-Fc was more potent than Tα1 in inhibiting the growth of 4T1 and MCF-7 breast cancer cells in vivo. Furthermore, in the 4T1 tumor model the mice treated with Tα1-Fc exhibited higher level of CD4 and CD8 cells compared with that of the mice Tα1 treated. The interferon-γ and interleukin-2 level in the Tα1-Fc-treated mice was higher than that in the Tα1-treated mice. Tα1-Fc could also alleviate immunosuppression induced by hydrocortisone. In summary, Tα1-Fc provides a novel potent strategy to recruit immune cells against tumors and enhance the antitumor activity of Tα1.