--- title: "Thymosin Alpha-1 | PepTracker Pro" url: https://peptrackerpro.com/peptides/thymosin-alpha-1 description: "A thymic peptide approved in some countries for immune modulation, studied for viral infections and cancer adjunct therapy." lang: en --- Skip to main content **Educational information only.** This site does not provide medical advice. Read full disclaimer (https://peptrackerpro.com/disclaimer) **Research-only content.** This page is for educational purposes and does not constitute medical advice. Read full disclaimer → (https://peptrackerpro.com/research-disclaimer) # Thymosin Alpha-1 High Evidence A thymic peptide approved in some countries for immune modulation, studied for viral infections and cancer adjunct therapy. Aliases Tα1 +2 more Evidence High Evidence Last Updated 2026-07-01 Reading Time 3 min ## What It Is Thymosin Alpha-1 (Tα1) is a 28-amino acid peptide naturally produced by the thymus gland that plays a central role in T-cell maturation, dendritic cell activation, and innate immune regulation. The synthetic version — thymalfasin, marketed as Zadaxin — is approved in over 35 countries for the treatment of hepatitis B, hepatitis C, and as an immune adjuvant in cancer therapy. It is one of the most clinically validated immune-modulating peptides in existence, with data from over 4,400 patients across more than 80 clinical trials spanning hepatitis, HIV adjunct therapy, cancer immunotherapy, sepsis, vaccine enhancement, and primary immunodeficiency disorders. Thymosin Alpha-1 enhances immune function by promoting T-cell differentiation, stimulating natural killer (NK) cell activity, and modulating cytokine production to shift immune responses toward a Th1-dominant profile. In oncology, it is being evaluated as a 'primer' for checkpoint immunotherapy: as of early 2026, at least three active Phase II trials are testing Thymosin Alpha-1 before or alongside anti-PD-1/PD-L1 therapy in hepatocellular carcinoma (HCC), non-small cell lung cancer (NSCLC), and gastric cancer. Its safety profile is well-established, with Grade 3–4 adverse events occurring in fewer than 5% of trial participants, primarily injection-site reactions and rare hypersensitivity responses. In the United States, Thymosin Alpha-1 was returned to Category 1 compounding eligibility under the FDA's February 2026 reclassification announcement by HHS Secretary Robert F. Kennedy Jr. This means it may be compounded by licensed 503A/503B pharmacies under physician prescription, though it remains unapproved by the FDA as a drug product. It is not available over the counter and requires medical supervision for use. Also known as: Tα1, Zadaxin, Thymalfasin ## Regulatory Status Category 1 — Bulk Compounding Returned to Category 1 compounding eligibility under FDA's February 2026 reclassification. May be compounded by 503A/503B pharmacies under physician prescription. Effective: February 2026 View FDA Source (https://www.fda.gov/drugs/human-drug-compounding/bulk-drug-substances-used-compounding) ## Why Researchers Study It Thymosin Alpha-1 is studied because of its broad, well-documented immunomodulatory effects and its established safety record across thousands of patients in controlled trials. Its ability to enhance both innate and adaptive immunity — particularly T-cell and NK cell function — makes it relevant to cancer immunotherapy, chronic viral infections, sepsis management, and vaccine adjuvant research. The 2026 FDA reclassification has renewed interest in its clinical applications within the United States. ## Proposed Mechanisms - Promotes differentiation and maturation of T-cells from thymic progenitors - Stimulates natural killer (NK) cell cytotoxic activity - Activates dendritic cells and enhances antigen presentation - Modulates cytokine profiles, shifting toward Th1-dominant immune responses - Upregulates toll-like receptors (TLR2, TLR9), enhancing innate pathogen recognition - May enhance efficacy of checkpoint inhibitors (anti-PD-1/PD-L1) by priming the tumor microenvironment ## Evidence Snapshot High Evidence Low Medium High | Study Type | Model | Outcome | Link | | --- | --- | --- | --- | | Meta-analysis (human) | Chronic hepatitis B — adjunct to antiviral therapy | Improved virological response rates and seroconversion when added to standard antiviral regimens | Source: https://pubmed.ncbi.nlm.nih.gov/38308608/ | | Phase II (ongoing, 2026) | HCC, NSCLC, and gastric cancer — Tα1 + anti-PD-1/PD-L1 | At least three active trials evaluating Tα1 as immunotherapy primer; results pending | Source: https://clinicaltrials.gov/ | | RCT (human) | Sepsis — ICU patients | Improved immune reconstitution and reduced 28-day mortality in septic patients with immunosuppression | Source: https://pubmed.ncbi.nlm.nih.gov/ | | Safety review (human) | Comprehensive safety analysis across 80+ clinical trials | Grade 3–4 adverse events <5% of participants; primarily injection-site reactions | Source: https://pubmed.ncbi.nlm.nih.gov/38308608/ | ## Commonly Discussed Benefits Immune Support: https://peptrackerpro.com/benefits/immune-support Longevity: https://peptrackerpro.com/benefits/longevity Inflammation: https://peptrackerpro.com/benefits/inflammation Researching Thymosin Alpha-1? Track it, set reminders, and keep notes in the free app. Track in App (https://app.peptrackerpro.com/?add=thymosin-alpha-1) ## Safety & Cautions - Approved in many countries but not FDA-approved in the US - Requires medical supervision for use - May interact with immunosuppressive medications - Not a substitute for standard medical treatment ## Comparisons See how Thymosin Alpha-1 compares to related peptides: Thymosin Alpha-1 vs Efzofitimod: https://peptrackerpro.com/compare/thymosin-alpha-1-vs-efzofitimod Thymosin Alpha-1 vs Epithalon: https://peptrackerpro.com/compare/thymosin-alpha-1-vs-epithalon Thymosin Alpha-1 vs Selank: https://peptrackerpro.com/compare/thymosin-alpha-1-vs-selank Thymosin Alpha-1 vs Zilucoplan: https://peptrackerpro.com/compare/thymosin-alpha-1-vs-zilucoplan ## Calculator Tools Use our research tools to explore dosing and reconstitution data: Reconstitution Calculator: https://peptrackerpro.com/calculators ## Citations 1. [1] Tuthill C. et al. — Thymosin alpha 1: past clinical experience and future promise. Ann N Y Acad Sci. 2010 PubMed (https://pubmed.ncbi.nlm.nih.gov/) 2. [2] Comprehensive Review of the Safety and Efficacy of Thymosin Alpha 1 in Human Clinical Trials — PubMed 2024 PubMed (https://pubmed.ncbi.nlm.nih.gov/38308608/) 3. [3] Thymosin Alpha-1 Clinical Trials 2026 — Real Peptides PubMed (https://www.realpeptides.co/thymosin-alpha-1-clinical-trials-2026/) ### Keep researching in the app - Log Thymosin Alpha-1 to your private tracker - Set a dosing reminder - Compare it side-by-side with your stack Open PepTracker Pro Free: https://app.peptrackerpro.com/?add=thymosin-alpha-1 Browse more peptides: https://peptrackerpro.com/peptides ## Related Peptides ### Efzofitimod Medium Evidence A first-in-class, intravenous immunomodulatory fusion peptide derived from histidyl-tRNA synthetase that selectively binds neuropilin-2 (NRP2) to dampen inflammation in the lung; in Phase 3 development for pulmonary sarcoidosis, an interstitial lung disease. Inflammation: https://peptrackerpro.com/benefits/inflammation Immune Support: https://peptrackerpro.com/benefits/immune-support View Details: https://peptrackerpro.com/peptides/efzofitimod \+ Compare: https://peptrackerpro.com/compare?select=efzofitimod Track in App: https://app.peptrackerpro.com/?add=efzofitimod ### Epithalon Low Evidence A tetrapeptide studied for its potential to activate telomerase and influence biological aging markers. Longevity: https://peptrackerpro.com/benefits/longevity Anti-Aging: https://peptrackerpro.com/benefits/anti-aging Sleep: https://peptrackerpro.com/benefits/sleep Immune Support: https://peptrackerpro.com/benefits/immune-support View Details: https://peptrackerpro.com/peptides/epithalon \+ Compare: https://peptrackerpro.com/compare?select=epithalon Track in App: https://app.peptrackerpro.com/?add=epithalon ### Selank Medium Evidence A synthetic peptide analog of tuftsin studied for anxiolytic and nootropic properties. Anxiety Relief (https://peptrackerpro.com/benefits/anxiety-relief)Mood (https://peptrackerpro.com/benefits/mood)Cognition (https://peptrackerpro.com/benefits/cognition)Neuroprotection (https://peptrackerpro.com/benefits/neuroprotection)+1 more View Details: https://peptrackerpro.com/peptides/selank \+ Compare: https://peptrackerpro.com/compare?select=selank Track in App: https://app.peptrackerpro.com/?add=selank ### Zilucoplan High Evidence A self-administered, once-daily subcutaneous macrocyclic peptide that inhibits complement component 5 (C5), FDA- and EMA-approved for anti-AChR-positive generalized myasthenia gravis. Immune Modulation: https://peptrackerpro.com/benefits/immune-modulation Neuromuscular Function: https://peptrackerpro.com/benefits/neuromuscular-function View Details: https://peptrackerpro.com/peptides/zilucoplan \+ Compare: https://peptrackerpro.com/compare?select=zilucoplan Track in App: https://app.peptrackerpro.com/?add=zilucoplan ## Structured data ```json [ { "@context": "https://schema.org", "@type": "Organization", "name": "PepTracker Pro", "url": "https://peptrackerpro.com", "logo": "https://peptrackerpro.com/favicon.png", "description": "Evidence-based educational resource dedicated to improving peptide research literacy.", "contactPoint": { "@type": "ContactPoint", "email": "hello@peptrackerpro.com", "contactType": "customer support" }, "sameAs": [] }, { "@context": "https://schema.org", "@type": "MedicalWebPage", "name": "Thymosin Alpha-1", "description": "A thymic peptide approved in some countries for immune modulation, studied for viral infections and cancer adjunct therapy.", "url": "https://peptrackerpro.com/peptides/thymosin-alpha-1", "lastReviewed": "2026-07-01", "reviewedBy": { "@type": "Organization", "name": "PepTracker Pro Research Team", "url": "https://peptrackerpro.com" }, "isPartOf": { "@type": "WebSite", "name": "PepTracker Pro", "url": "https://peptrackerpro.com" } }, { "@context": "https://schema.org", "@type": "BreadcrumbList", "itemListElement": [ { "@type": "ListItem", "position": 1, "name": "Home", "item": "https://peptrackerpro.com" }, { "@type": "ListItem", "position": 2, "name": "Peptides", "item": "https://peptrackerpro.com/peptides" }, { "@type": "ListItem", "position": 3, "name": "Thymosin Alpha-1", "item": "https://peptrackerpro.com/peptides/thymosin-alpha-1" } ] }, { "@context": "https://schema.org", "@type": "FAQPage", "mainEntity": [ { "@type": "Question", "name": "People researching immune-modulating peptides?", "acceptedAnswer": { "@type": "Answer", "text": "Thymosin Alpha-1 is a research peptide studied in preclinical models. 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