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
619
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.

The Immunomodulatory Activity of Thymosin Alpha 1 on Tumor Cell Lines and Distinct Immune Cell Subsets
OncoTargets and therapy · 2025 · PubMed
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

PDD screens compounds based on functional effects without requiring knowledge of specific molecular targets.; PDD can lead to unexpected therapeutic applications and addresses the complexity of human diseases.; Challenges in PDD include hit validation and target deconvolution, but significant achievements have been made in the big data era.; The article uses thymosin alpha-1 as a case study to show how PDD applies to a thymic peptide hormone in preclinical and clinical settings.

Enhanced Immunomodulatory Effects of Thymosin-Alpha-1 in Combination with Polyanionic Carbosilane Dendrimers against HCMV Infection
International journal of molecular sciences · 2024 · PubMed
Comprehensive Review of the Safety and Efficacy of Thymosin Alpha 1 in Human Clinical Trials
Alternative therapies in health and medicine · 2024 · PubMed

T 1 demonstrated significant effectiveness in treating COVID-19, autoimmune disorders, and cancer across diverse clinical trials.; Evidence from over 11,000 subjects in more than 30 trials consistently showed T 1's safety and efficacy, contradicting the FDA's 2023 restriction.; The review recommends that the FDA permits 503A compounding pharmacies to compound T 1 to ensure its continued availability as a life-saving peptide.

Mechanism and clinical application of thymosin in the treatment of lung cancer
Frontiers in immunology · 2023 · PubMed
Thymosin alpha 1 restores the immune homeostasis in lymphocytes during Post-Acute sequelae of SARS-CoV-2 infection
International immunopharmacology · 2023 · PubMed

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 619 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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