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
Reta Peptide 10 mg $175.00 83
Ascension Peptides 10 mg $71.00 83
Cocer Peptides 10 mg $185.00 82
MedGe Peptides 10 mg $175.00 82
Blank Peptides 10 mg $75.00 81
OROS Research 5 mg $44.99 79
Texpeptide 5 mg $50.00 69
Crystal Peptides 5 mg $43.99 66
Qing Li Peptide 63
Certified Peptides 10 mg $78.00 61
MEI-PEPETIDE 2 mg $55.00 48
DongCheng Peptide 46
Puratek Peptides 10 mg $59.95 44
Mandy 5 mg $80.00 43
MJT peptides 5 mg $106.00 39
Nextech Labs 10 mg $65.00 24
NG Peptide 10 mg $45.00
Strate Labs 12.5 mg $49.95
Kimera Chems $76.99
Welli Labs $39.99
synthesispeptides.io 10 mg $74.99
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
Lumi Peptides $52.00
Modern Research Peptides $36.99
Oasis Labs 10 mg $65.00
Oneday Compounds 10 mg $45.49
Paramount Peptides 10 mg $157.25
Paramount Peptides 10 mg $97.75
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 $52.50
True Peptide 10 mg $65.00
Wellness Peptides 5 mg $45.00
Wellness Peptides 10 mg $45.00
optimasupply.is $65.00
realpeptides.co $115.00

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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A Prospective, Multicenter, Open-label, Single-arm Phase II Clinical Study Evaluating the Efficacy and Safety of Spatially Fractionated Radiotherapy Combined With the PraG Strategy for the Treatment of Soft Tissue Sarcoma
· ClinicalTrials.gov (2026) · rct

The primary objective of this clinical trial is to evaluate the efficacy and safety of spatially fractionated radiotherapy combined with the PraG strategy in the treatment of soft tissue sarcoma (STS). The main questions it aims to answer are: 1.

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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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Thymalfasin (Thymosin Alpha 1; Ta1) as an Enhancer of Vaccine Response Among Older Adults Receiving Booster Doses of COVID-19 Vaccine
· ClinicalTrials.gov (2024) · rct

The goal of this research is to learn more about ZADAXIN® (trade name; thymalfasin generic; Ta1 for short) and determine if Ta1 has any benefit in increasing the immune response to the COVID-19 vaccine. Ta1 has been shown to stimulate the immune system to fight infections.

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Neoadjuvant Chemoradiotherapy Combined With PD-1 Inhibitor and Thymalfasin for pMMR/MSS Locally Advanced Mid-low Rectal Cancer
· ClinicalTrials.gov (2024) · rct

This is an open, prospective, multi-center, single-arm phase II clinical study assessing the efficacy and safety of neoadjuvant chemoradiotherapy combined with PD-1 inhibitor and thymalfasin in patients with pMMR/MSS locally advanced middle and low rectal cancer.

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Protective Effect of Thymosin Α1 Against Negative Immune Dysregulation and Organ Dysfunction After Acute Aortic Dissection Surgery (PANDA II)
· ClinicalTrials.gov (2022) · rct

Systemic inflammatory response syndrome (SIRS) and multiple organ dysfunction syndrome (MODS) are the major causes of death in patients with acute aortic syndrome (AAS). Therefore, the prevention of SIRS and MODS is of great clinical value, and immunomodulatory therapy with thymosin alpha 1 may be beneficial.

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Zadaxin and HIV-positive Patients With Immune Reconstitution Disorder
· ClinicalTrials.gov (2021) · rct

The purpose of this study is to evaluate the safety and efficacy of Zadaxin® in the treatment of HIV-positive patients with immune reconstitution disorders.

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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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Efficacy of Thymosin Alpha 1 on Improving Monocyte Function for Sepsis
· ClinicalTrials.gov (2016) · rct

The purpose of this study is to determine whether thymosin alpha 1 is effective on improving monocyte function and has the desired pharmacologic activity for sepsis

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