Clinical Applications and Evidence Landscape of Thymosin Alpha 1 as an Immunomodulatory Adjunct in Cancer Care: A Scoping Review

Background: Thymosin alpha 1 (Tα1, thymalfasin) is a thymus-derived immunomodulatory peptide investigated as an adjunctive therapy in cancer care. Although studied across malignancies, its evidence landscape has not been systematically mapped. This scoping review characterized treatment contexts, intervention patterns, outcome domains, and safety reporting of clinical studies evaluating Tα1 in patients with cancer. Methods: PubMed, Embase, and CENTRAL were searched for clinical studies of Tα1 in patients with cancer published from January 2016 to March 2026. Eligible studies included randomized controlled trials, non-randomized studies, observational studies, and case-based reports. Data on study characteristics, cancer type, intervention features, comparators, outcomes, and adverse-event reporting were charted and synthesized descriptively. Results: Twenty-six clinical publications were included. Most were conducted in China, and retrospective observational studies and case reports predominated. Hepatobiliary, thoracic, and gastrointestinal cancers were the most frequently studied clusters. Classical Tα1 was administered mainly by subcutaneous injection, most commonly at 1.6 mg, and used primarily as an adjunct to chemotherapy, radiotherapy, chemoradiotherapy, targeted therapy, immune checkpoint inhibitors, or postoperative and supportive care. Outcomes included tumor response, survival, recurrence, immune and inflammatory markers, treatment-related toxicity, functional status, and quality of life. Several studies reported favorable clinical, immune-related, or treatment-tolerance signals, but heterogeneity limited comparability. Safety reporting was inconsistent. One case described severe multisystem immune-related toxicity during combination treatment without establishing Tα1-specific causality. Conclusions: Tα1 has been investigated mainly as an adjunctive immunomodulatory strategy in cancer care. Prospective controlled studies with standardized dosing, defined treatment contexts, consistent outcomes, and systematic harms reporting are needed.