Thymosin Alpha-1

approved

Also known as: Thymalfasin, Zadaxin, Tα1

Thymosin Alpha-1 (Tα1), a 28-amino acid peptide derived from the thymus, primarily modulates immune function by enhancing T-cell maturation, differentiation, and activity. It acts through Toll-like receptor (TLR) signaling, particularly TLR2 and TLR9, leading to activation of dendritic cells and increased production of cytokines such as interferon-alpha and interleukin-2. This mechanism promotes a shift toward a Th1-dominant immune response, improving antigen presentation and cytotoxic T-cell activity. Tα1 also reduces apoptosis in immune cells and supports regulatory T-cell balance, contributing to its immunomodulatory effects. Key research findings demonstrate Tα1’s efficacy in enhancing immune responses against viral infections and as an adjuvant in vaccination protocols. Clinical studies have shown improved survival and reduced infection rates in patients with chronic hepatitis B and C, as well as enhanced immune recovery in immunocompromised individuals, such as those with sepsis or undergoing cancer therapy. Tα1 has also been investigated for its role in improving vaccine responses, including in influenza and COVID-19 contexts, and for its potential to modulate immune dysfunction in autoimmune conditions. Clinically, Thymosin Alpha-1 is approved in over 30 countries (e.g., as Zadaxin) for the treatment of chronic hepatitis B and as an immune adjuvant in various infectious diseases and cancer immunotherapy protocols. It is administered subcutaneously and has a favorable safety profile, with mild local reactions being the most common adverse effects. Despite its approval status, ongoing research continues to explore its utility in broader immune-related disorders, including HIV, cystic fibrosis, and as a supportive therapy in checkpoint inhibitor regimens. For research purposes only — not medical advice.

Key data

Category
Immune Modulation
Molecular weight
3108.3 g/mol
Molecular formula
C129H215N33O55
CAS number
62304-98-7
Administration
subcutaneous
Research status
approved
References
618
Tags
immune, thymic, approved, antiviral

Research & studies

Aging and Thymosin Alpha-1
International journal of molecular sciences · 2025 · PubMed

Aging causes thymic involution, reducing T-cell production and increasing susceptibility to age-related diseases.; Thymosin alpha-1 has immunomodulatory, anti-inflammatory, and antioxidant properties that restore immune function.; Tα1 improves vaccine response in the elderly and mitigates immunosenescence in preclinical and clinical studies.; Refnot, a fusion of TNF and Tα1, offers reduced toxicity and promising therapeutic potential for age-related immune dysfunction.

Thymosin α1 reverses oncolytic adenovirus-induced M2 polarization of macrophages to improve antitumor immunity and therapeutic efficacy
Cell reports. Medicine · 2024 · PubMed

ADV induces M2 polarization of TAMs and increases Treg infiltration in the TME.; Tα1 reprograms M2-like TAMs toward an antitumoral phenotype.; ADV-Tα1 combination therapy enhances antitumor efficacy via CD8+ T cells.; Findings support clinical translation for oncolytic adenovirus combination therapy.

Phenotypic drug discovery: a case for thymosin alpha-1
Frontiers in medicine · 2024 · PubMed
Thymosin α-1 in cancer therapy: Immunoregulation and potential applications
International immunopharmacology · 2023 · PubMed
A Pilot Trial of Thymalfasin (Thymosin-α-1) to Treat Hospitalized Patients With Hypoxemia and Lymphocytopenia Due to Coronavirus Disease 2019 Infection
The Journal of infectious diseases · 2023 · PubMed

Incidence of clinical recovery was higher for treated patients but not statistically significant (low-flow oxygen: subdistribution HR 1.48; high-flow oxygen: 1.28).; Treated patients with baseline low-flow oxygen had 3.84 times more CD4+ T cells on day 5 versus day 1 compared to controls (P = .01).; Nine serious adverse events in treated patients were deemed unrelated to thymalfasin.

Thymosin alpha 1: A comprehensive review of the literature
World journal of virology · 2020 · PubMed

Thymosin alpha 1 enhances immune function and has been used for immunocompromised states, malignancies, and infections.; It may improve outcomes in severe COVID-19 by preventing excessive T cell activation.; The peptide has known antibacterial and antiviral properties.; Further research is needed to explore its repurposing against SARS-CoV-2.

Serum thymosin alpha 1 levels in normal and pathological conditions
Expert opinion on biological therapy · 2018 · PubMed

Diseases like hepatitis B, psoriatic arthritis, multiple sclerosis, and sepsis show significantly lower serum Ta1 levels than healthy individuals.; Cystic fibrosis patients have lower Ta1 levels in sputum compared to healthy controls.; Low serum Ta1 levels are predictive or associated with various pathological conditions.; Knowing baseline serum Ta1 levels is crucial for establishing effective treatment protocols and monitoring therapy.

Thymosin alpha 1 treatment for patients with sepsis
Expert opinion on biological therapy · 2018 · PubMed

Single or combined Tα1 treatment reduces mortality in sepsis patients.; Tα1 improves HLA-DR expression on monocytes.; Tα1 diminishes the incidence of secondary infection.; Selecting immunosuppressed septic patients may better reveal Tα1 efficacy in future trials.

Frequently asked questions

What is Thymosin Alpha-1?

Thymosin Alpha-1 (Tα1), a 28-amino acid peptide derived from the thymus, primarily modulates immune function by enhancing T-cell maturation, differentiation, and activity. It acts through Toll-like receptor (TLR) signaling, particularly TLR2 and TLR9, leading to activation of dendritic cells and increased production of

How does Thymosin Alpha-1 work?

28-aa thymic peptide that enhances T-cell maturation and TLR signaling; approved in many countries for hepatitis and as an immune adjuvant.

What is the research status of Thymosin Alpha-1?

Thymosin Alpha-1 is currently classified as approved, with 618 research references on record. This is for research purposes only and is not medical advice.

What is the molecular weight of Thymosin Alpha-1?

Thymosin Alpha-1 has a molecular weight of approximately 3108.3 g/mol (formula C129H215N33O55).

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