Approved outside US / not FDA-approved

Thymosin Alpha-1

Acetylated 28-aa thymic peptide (thymalfasin) — ≠ Thymalin ≠ TB-500.

Editorial review:

What evidence says

Evidence snapshot

This drawer marks papers. It is not a plan, a dose, or a source. A paper is a bounded report. It is not a protocol. Grades name the object. They are not a safety rating.

Identity lock. Thymosin alpha-1 (Tα1; INN thymalfasin) is an acetylated 28-amino-acid thymic peptide. PubChem CID 16130571; formula C129H215N33O55 / MW 3108.3; CAS 62304-98-7 (common; also 69440-99-9, 69521-94-4, 1337515-90-8 on record). It is not Thymalin (thymic polypeptide complex — separate drawer), not TB-500 / Ac-LKKTETQ, and not full-length thymosin β4. Some jurisdictions historically authorized thymalfasin (e.g. hepatitis-related programs under names such as Zadaxin); US FDA approval for a broad immuno-oncology or consumer “immune peptide” indication is not assumed here — mark jurisdiction carefully. This drawer marks papers. It is not use advice.

Bottom line

Human literature includes hepatitis B / cirrhosis combination trials, sepsis immunomodulation meta-analyses, a large 2025 TESTS Phase 3 sepsis mortality RCT (primary mortality endpoint not met), and COVID-era exploratory/immunology work. Preclinical and narrative immuno-oncology pieces are secondary. Do not inflate a negative or null Phase 3 mortality result into a sepsis glow, and do not blur this object into Thymalin or Tβ4.

Papers

Sepsis — pivotal and pooled human

PMID 39814420 — Wu 2025

Tested: TESTS — multicentre, double-blind, randomised, placebo-controlled Phase 3 trial of thymosin α1 on 28-day all-cause mortality in adults with sepsis (China centers).

Does not show: a clear mortality benefit (primary endpoint not met); exploratory age/diabetes subgroup signals are not a labeled sepsis indication.

PMID 26522590 — Han 2015

Tested: meta-analysis of ulinastatin- and thymosin α1-based immunomodulatory strategies in sepsis.

Does not show: a modern Phase 3 replacement for TESTS, or thymosin α1 monotherapy proof in isolation from combination regimens.

PMID 20549321 — Wang 2011

Tested: clinical association of thymosin alpha-1 with cellular immunity and infection outcomes in severe acute pancreatitis patients.

Does not show: a large confirmatory sepsis mortality RCT (see TESTS), or pancreatitis as an approved indication everywhere.

Chronic hepatitis B / cirrhosis (human)

PMID 18078676 — Yang 2008

Tested: meta-analysis comparing thymosin alpha-1 versus interferon-α in chronic hepatitis B.

Does not show: a contemporary first-line antiviral standard of care replacement, or identity with Thymalin.

PMID 25640173 — Wu 2015

Tested: editorial/review of thymosin alpha-1 treatment in chronic hepatitis B (alone or with nucleos(t)ide analogues).

Does not show: a new primary randomized package by itself.

PMID 30063860 — Wu 2019

Tested: prospective multicenter randomized open-label study of entecavir plus thymosin alpha-1 versus entecavir alone in HBV-related compensated cirrhosis (endpoint events including decompensation/HCC/death).

Does not show: a statistically clear primary-endpoint win for combination therapy in that report’s main analysis; HCC “tendency” language is not proof of prevention.

COVID-era / immunology context (exploratory)

PMID 33506065 — Matteucci 2021

Tested: ex vivo / blood-cell work on thymosin alpha-1 mitigating cytokine-storm features in COVID-19 patient samples.

Does not show: a confirmatory clinical COVID mortality trial, or an approved COVID indication.

PMID 37110771 — Tao 2023

Tested: review of thymosin α1 mechanisms and clinical application narratives in viral infectious diseases.

Does not show: a new primary RCT; secondary synthesis only.

Secondary / identity context

PMID 11381492 — Ancell 2001

Tested: early clinical pharmacology / overview of thymosin alpha-1.

Does not show: contemporary Phase 3 sepsis or hepatitis standards by itself.

PMID 36871535 — Mao 2023

Tested: narrative review reimagining thymosin alpha-1 applications in the immuno-oncology era.

Does not show: a completed pivotal immuno-oncology approval package for unlabeled vial use.

What is not established

US broad approval as a consumer immune peptide. That TESTS proves sepsis mortality reduction (it did not meet its primary endpoint). Interchangeability with Thymalin, TB-500 fragment, or full Tβ4. That hepatitis combination signals equal a stand-alone anti-aging or wellness claim. Product identity for unlabeled preparations versus trial thymalfasin. This drawer does not provide use advice, schedules, or sourcing.

Selected sources

39814420 26522590 20549321 18078676 25640173 30063860 33506065 37110771 11381492 36871535

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