peptide wiki

Thymosin Alpha-1

aka Thymalfasin (trade name Zadaxin)

Immune Modulator

Mechanism

Thymosin Alpha-1 (Ta1) is a 28-amino-acid thymic peptide (Ac-SDAAVDTSSEITTKDLKEKKEVVEEAEN) approved as Zadaxin in 35+ countries for chronic hepatitis B/C and as an immune adjuvant. It is NOT FDA-approved in the US.

Identification

CAS number62304-98-7
Molecular formulaC129H215N33O55
SequenceSDAAVDTSSEITTKDLKEKKEVVEEAEN
Typical dose1.6 mg subcutaneous 2–3x/week (clinical standard); research protocols range 1.6–6.4 mg per dose
Half-life~2–3 hours (subcutaneous; elimination t½ <3 h confirmed by PK study)

Vendors selling Thymosin Alpha-1

VendorSizePriceListed purityTrust
Peptide Partners 10 mg $98.00 99
Glacier Aminos 10 mg $63.99 99
Moglabs 5 mg $36.00 96
BioLongevity Labs $249.97 96
BioLongevity Labs 10 mg $129.97 96
Orbitrex Peptides 10 mg $79.99 95
Profound Aminos 5 mg $49.00 95
Ion Peptide $42.00 95
Licensed Peptides 5 mg $359.95 95
Licensed Peptides 5 mg $61.99 95
Peptide Tech 5 mg $28.99 94
Mile High Compounds $69.99 94
Forge Performance Co. 10 mg $60.00 94
Amino Club $39.99 93
Riptide Wellness 10 mg $65.00 92
Hydro Research Peptides 10 mg $0.65 91
Skye Peptides 10 mg $79.00 90
Peptidology 10 mg $69.99 89
Peptide Plugs 10 mg $60.00 89
Verified Peptides 10 mg $80.00 86
EZ Peptides 10 mg $58.00 85
Simple Peptide 10 mg $86.00 85
Peptidegurus 3 mg 84
Peptidegurus 10 mg 84
Ascension Peptides 10 mg $71.00 84
Reta Peptide 10 mg 83
Cocer Peptides 10 mg $185.00 82
MedGe Peptides 10 mg $115.00 82
OROS Research 5 mg 79
Texpeptide 5 mg $50.00 70
Crystal Peptides 5 mg $43.99 66
Qing Li Peptide 63
Certified Peptides 10 mg $78.00 62
MEI-PEPETIDE 2 mg $55.00 48
DongCheng Peptide 46
Mandy 5 mg $80.00 43
MJT peptides 5 mg $106.00 39
NG Peptide 10 mg $45.00
Strate Labs 12.5 mg $49.95
Alpha Omega $86.00
Atomik Labz 10 mg $65.00
Biotech Peptides 10 mg $130.00
Bulk Peptides 5 mg $200.00
Core Peptides 10 mg $81.00
Core Peptides 5 mg $81.00
Flawless Compounds
Genetic Peptide 5 mg $65.00
Genetic Peptide 15 mg $65.00
Kimera Chems $76.99
Lumi Peptides $52.00
Modern Research Peptides 5 mg $36.99
Oasis Labs 10 mg $65.00
Oneday Compounds 10 mg $84.99
Paramount Peptides 10 mg $125.00
Paramount Peptides 10 mg $115.00
Peptide Crafters 10 mg $65.00
Peptira $59.00
Pepvida Labs 5 mg $42.00
Platinum Lion 10 mg $64.99
Polaris Peptides 10 mg $65.00
S1 Research 10 mg $44.00
Solution Peptides 10 mg $65.00
Soma Peptides $219.00
Soma Peptides 16 mg $124.00
Southern Aminos 10 mg $74.25
True Peptide 10 mg $65.00
Welli Labs $39.99
Wellness Peptides 5 mg $45.00
Wellness Peptides 10 mg $45.00

Research

Thymosin Alpha-1 Restores Chemotherapy-Induced Antitumor Immunity by Chaperoning a MicroRNA Ligand of TLR7 in Dendritic Cells
Wei Y, Chen J, Zhang Y, Liu Y, Zhu F, Wang X, Zhou X, Wu C, Zhang W, Chen J, Zhang Y, Pan N, Chen K, Zheng S, Yan C, Liu L, Wang L. · Cancer research (2026) ·

Chemotherapy induces cancer cell apoptosis and the release of apoptotic bodies (ABs) that are poorly immunogenic or immunosuppressive, creating a major barrier to the success of co-administered or second-line immunotherapies.

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A Case Report of a Multisystemic Immune-Related Adverse Event Caused by Sintilimab in Combination With Thymosin Alpha-1
Li T, Wu BL, Yu CL, Jin LY. · Clinical case reports (2026) ·

To report a case of a nasopharyngeal carcinoma patient who developed multisystem immune-related adverse events (irAEs) after treatment with sintilimab (PD-1 inhibitor) in combination with thymosin alpha-1 (Tα1). The patient presents with high fever, rash, interstitial pulmonary edema, and multiple organ failure.

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Aging and Thymosin Alpha-1
Simonova MA, Ivanov I, Shoshina NS, Komyakova AM, Makarov DA, Baranovskii DS, Klabukov ID, Telepenina KP, Atiakshin DA, Shegay PV, Kaprin AD, Stepanenko VN. · International journal of molecular sciences (2025) · review

Aging is characterized by immune decline, mainly due to thymic involution-the age-related shrinkage of the thymus gland. This leads to reduced T-cell production, chronic inflammation, and increased susceptibility to age-related diseases.

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The Immunomodulatory Activity of Thymosin Alpha 1 on Tumor Cell Lines and Distinct Immune Cell Subsets
Solmonese L, Lofiego MF, Fazio C, Marzani F, Piazzini F, Bello E, Celesti F, Giacobini G, Wang X, Maio M, Coral S, Di Giacomo AM, Covre A. · OncoTargets and therapy (2025) ·

Background The immune-balancing role of thymosin alpha 1 (Tα1) is well-recognized in contexts of immune dysregulation. Within the anti-tumor context, Tα1 demonstrated to act as an immune-enhancer, with potential roles in immunotherapy-based treatments.

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Thymosin alpha 1 alleviates inflammation and prevents infection in patients with severe acute pancreatitis through immune regulation: a systematic review and meta-analysis
Tian Y, Yao J, Ma Y, Zhang P, Zhou X, Xie W, Tang W. · Frontiers in immunology (2025) · meta-analysis

Background Immune and inflammatory disorders are part of the complex pathophysiological processes that exacerbate severe acute pancreatitis (SAP) and subsequent infection.

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The efficacy and safety of thymosin alpha-1 combined with lenvatinib plus sintilimab in unresectable hepatocellular carcinoma: a retrospective study
Yao S, Huang Q, Zou Y, Liu T, Yang Y, Huang T, Zhao Y, Dong X. · Scientific reports (2025) ·

To validate the efficacy and safety of thymosin α-1 combined with lenvatinib plus sintilimab in the treatment of unresectable hepatocellular carcinoma.

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Indications for an antidepressive effect of thymosin alpha-1 in a small open-label proof of concept study in common variable immune deficiency patients with depression
Aynekulu Mersha DG, Fromme SE, van Boven F, Arteaga-Henríquez G, Wijkhuijs A, van der Ent M, Bergmans R, Baune BT, Drexhage HA, Dalm V. · Brain, behavior, & immunity - health (2025) ·

Background A considerable proportion (21%) of patients with common variable immunodeficiency (CVID) suffers from depression. These subjects are characterized by reduced naïve T cells and a premature T cell senescence similar to that of patients with major depressive disorder (MDD).

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Phenotypic drug discovery: a case for thymosin alpha-1
Garaci E, Paci M, Matteucci C, Costantini C, Puccetti P, Romani L. · Frontiers in medicine (2024) · review

Phenotypic drug discovery (PDD) involves screening compounds for their effects on cells, tissues, or whole organisms without necessarily understanding the underlying molecular targets. PDD differs from target-based strategies as it does not require knowledge of a specific drug target or its role in the disease.

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Thymosin Alpha 1 Plus Routine Treatment for the Acute Exacerbation of Chronic Obstructive Pulmonary Disease: A Systematic Review and Meta-Analysis
Cao A, Feng F, Zhou X. · Journal of the College of Physicians and Surgeons--Pakistan : JCPSP (2024) · meta-analysis

This systematic review was conducted to assess the curative effect of Thymosin alpha 1 in the acute exacerbation of chronic obstructive pulmonary disease (AECOPD) patients.

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Comprehensive Review of the Safety and Efficacy of Thymosin Alpha 1 in Human Clinical Trials
Dinetz E, Lee E. · Alternative therapies in health and medicine (2024) · review

Objective This study aims to assess the safety and efficacy of Thymosin Alpha 1 (Tα1) through a comprehensive narrative review of clinical studies involving over 11 000 human subjects in more than 30 trials.

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PD-1 inhibitor combined with SBRT, GM-CSF, and thymosin alpha-1 in metastatic breast cancer: A case report and literature review
Yu J, Wang Q, Wang L, Zong D, He X. · Medicine (2024) · review

Rationale Triple-negative breast cancer is characterized by a worse prognosis compared with other breast cancer subtypes, especially in the case of pretreated metastatic triple-negative breast cancer (mTNBC).

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Enhanced Immunomodulatory Effects of Thymosin-Alpha-1 in Combination with Polyanionic Carbosilane Dendrimers against HCMV Infection
Espinar-Buitrago MS, Magro-López E, Vázquez-Alejo E, Muñoz-Fernández MÁ. · International journal of molecular sciences (2024) ·

Resistance and toxicity associated with current treatments for human cytomegalovirus (HCMV) infection highlight the need for alternatives and immunotherapy has emerged as a promising strategy.

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Radiotherapy With Sequential Chemotherapy Combined With PD-1 Inhibitor and Thymalfasin for BRPC
· ClinicalTrials.gov (2024) · rct

This is a prospective, single-center, single-arm, phase II clinical study.

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Thymosin Alpha 1 Combined With Anti-PD-1 Monoclonal Antibody in Elderly Patients With Advanced Melanoma
· ClinicalTrials.gov (2023) · rct

Primary Objective: To evaluate the effectiveness of Thymosin Alpha-1 combined with PD-1 monoclonal antibody in elderly patients with advanced melanoma . Secondary Objective: To evaluate the safety and tolerability of adenpeptide-α1 combined with PD-1 antibody in elderly patients with advanced melanoma .

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Thymosin Alpha 1 to Prevent COVID-19 Infection in Renal Dialysis Patients
· ClinicalTrials.gov (2021) · rct

Thymalfasin (thymosin alpha 1 or Ta1), the active pharmaceutical ingredient in ZADAXIN® injection, is a 28-amino acid synthetic peptide, identical to natural Ta1 produced by the thymus gland.

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Thymosin Alpha 1 in the Prevention of Pancreatic Infection Following Acute Necrotizing Pancreatitis
· ClinicalTrials.gov (2018) · rct

Infected pancreatic necrosis and its related septic complications are the major cause of death in patients with acute pancreatitis, therefore prevention of pancreatic infection is of great clinical value in the treatment of AP.

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Radiotherapy Combined With Thymosin for Metastatic NSCLC Patients Who Showed Stable Disease After First Line TKI Therapy
· ClinicalTrials.gov (2016) · rct

The investigators postulated that the exploitation of the pro-immunogenic effects of radiotherapy with thymosin might result in abscopal responses among patients with metastatic cancer.

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SBRT Combination With rhGM-CSF and Tα1 for Stage IV NSCLC Patients Who Failed in Second-line Chemotherapy
· ClinicalTrials.gov (2016) · rct

The purpose of this study is to determine whether stereotactic body radiotherapy (SBRT) combined with recombined human granulocyte-macrophage colony stimulating factor(rhGM-CSF) and Thymosin Alpha 1 is safe, effective in the treatment of stage IV NSCLC patients who failed in second-line chemotherapy.

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Thymalfasin Adjuvant Therapy in Hepatitis B Virus (HBV)-Related Hepatocellular Carcinoma (HCC) After Curative Resection
· ClinicalTrials.gov (2015) · rct

Efficacy and safety of Thymalfasin adjuvant therapy in HBV-related HCC after curative resection.

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Efficacy of Thymosin alpha1 for Severe Sepsis
· ClinicalTrials.gov (2008) · rct

The purpose of this study is to evaluate the efficacy of thymosin alpha 1 for treating severe sepsis.

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