Thymosin α1 combined with immune checkpoint inhibitors: synergistic remodeling of the tumor immune microenvironment to enhance clinical efficacy and safety.

This review examines the rationale and emerging evidence for combining Thymosin α1 (Tα1) — a naturally occurring, pleiotropic immunomodulatory peptide — with immune checkpoint inhibitors (ICIs) in the treatment of solid tumors. The authors first outline the biological characteristics of Tα1, highlighting its dual role in enhancing immune competence (e.g., promoting T-cell maturation and activation) while simultaneously regulating excessive immune responses. They then synthesize preclinical and clinical evidence suggesting that Tα1 may address key limitations of ICI monotherapy, including tumor heterogeneity, immunosuppressive tumor microenvironments, and immune-related adverse events (irAEs). The review argues that Tα1 can synergistically remodel the tumor immune microenvironment when combined with ICIs, potentially improving overall response rates. Preliminary clinical findings cited in the review indicate promising efficacy and manageable safety profiles for the combination. The authors acknowledge that the current evidence base relies heavily on early-phase or smaller studies and explicitly call for large-scale, long-term clinical trials to validate sustained benefits. As a narrative review, it does not generate new primary data, and conclusions are limited by the quality and scale of the underlying studies reviewed.

Why this grade: This is a narrative review synthesizing preclinical and early clinical data; it generates no new primary evidence and the authors themselves note the need for large-scale trials to confirm findings.