Thymogen

Overview

Thymogen is a synthetic dipeptide — two amino acids, glutamic acid joined to tryptophan (Glu-Trp, single-letter E-W). The marketed substance is the monosodium salt; the corresponding free acid carries the international name oglufanide (CAS 38101-59-6, formula C16H19N3O5, molecular weight 333.34, PubChem CID 100094). It comes from the Russian Khavinson/Morozov "peptide bioregulator" school and is described as a short-peptide fragment derived from the thymic extract Thymalin.

Its evidence picture is genuinely mixed, which is why it is filed here as disputed rather than clearly established. On one side: a long-standing Russian registration as an immunomodulator, plus older, mostly preclinical mechanism papers. On the other: no completed Western approval, and mechanism claims that rest largely on animal and in-vitro work. The free-acid form (oglufanide) did progress into Western clinical development — it held US Investigational New Drug (IND) status and an FDA Orphan Drug designation for ovarian cancer (September 2001), and was studied for cancer and chronic hepatitis C — but no marketing approval resulted, and no robust positive Phase 3 outcome was located.

Chemistry and structure

The chemistry of the free acid is firmly established (PubChem). The salt form is less settled: the value CAS 122933-59-9 is listed by suppliers as both the monosodium and the disodium salt, so the exact stoichiometry — and therefore the exact salt molecular weight and formula — is reported inconsistently and was not independently re-verified in this pass. Only the free-acid oglufanide was confirmed.

Mechanism of action

All of the following are proposed mechanisms; note the evidence tier on each and that much of it is older, largely Russian, and preclinical.

• Immunomodulation — T-cell differentiation and recognition. Attributed activity includes activating T-cell differentiation and T-cell recognition of peptide-MHC complexes, altering intracellular cyclic-nucleotide balance, and stimulating neutrophil chemotaxis/phagocytosis. [Animal] — Khavinson-school work; mechanistic detail not independently confirmed at the human clinical level. (Source: DrugBank DB05779; Thymalin context, PMC8365293.)
• Cytokine and adhesion-molecule signalling. alpha-Glu-Trp reduced TNF-alpha-induced IL-1alpha, increased TNF-alpha-stimulated ICAM-1 on endothelial cells, and reduced TNF-alpha-induced IL-8 secretion. [In vitro] — cell-culture study (endothelial / mononuclear cells; THP-1 monocyte/macrophage line). (Source: Cell and Tissue Biology, 2023; PMC8999041.)
• Slows aging markers and inhibits spontaneous carcinogenesis. [Animal] — rat study (Anisimov / Khavinson school); preclinical only. (Source: Anisimov et al., ResearchGate.)
• Anti-angiogenic / inhibits VEGF activity — the stated basis for the ovarian-cancer orphan indication. [In vitro] — not established in humans. (Source: DrugBank DB05779.)
• Binds a specific AACG nucleotide motif in DNA to influence gene expression. [Hypothesis] — the Khavinson-school "peptide-DNA epigenetic regulation" idea; speculative, not a confirmed clinical mechanism. (Source: Khavinson-school reviews.)

Research and evidence

Human evidence. Limited and inconclusive in the Western literature. The free-acid form (oglufanide) held US IND status and an FDA Orphan Drug designation for ovarian cancer (Sept 2001), and was taken into trials for cancer and chronic hepatitis C (a US HCV trial was recruiting into roughly 2007 under Implicit Bioscience, which acquired the molecule in 2005). [Human] No trial documented here led to FDA or EMA marketing approval, and no robust positive Phase 3 outcome was found. In Russia, Thymogen has long been marketed/registered for immunocorrection, but the supporting clinical literature is older, mostly Russian-language, and methodologically limited — not equivalent to modern regulatory-grade efficacy evidence. Net: trials existed, but efficacy is not established to FDA/EMA standard.

Status and regulation

Orphan/IND status and a foreign (Russian) registration do not constitute FDA or EMA authorisation. The definitive current Russian registration number/status was not read from an official Russian registry in this pass (it is inferred from secondary sources), and the outcomes of the US oglufanide trials were not located — efficacy remains unestablished to FDA/EMA standard.

Safety

• Human safety/adverse-event profile: not characterised in the sources reviewed here.
• Reported activity is largely animal and in-vitro; a preclinical safety signal (or its absence) does not transfer to humans.
• Material sold outside Russia's regulated channel is not the registered medicine and may differ in identity, purity, and sterility.
• WADA status: not found. No source addressing prohibited-list classification was located; this does not mean "permitted," and non-approval must not be read as an automatic S0 classification.

Legal status

Outside its Russian registration, Thymogen / oglufanide is classified as a research reagent. That classification is not permission for human use: "no specific ban" is not affirmative authorisation, and a compound becomes an unauthorised medicine the moment it is intended for human use. WADA sport-prohibition is a separate axis from legality — and no WADA class code is asserted for this compound by any source found, so none is stated here. Regulatory status differs by country and changes over time. This is not legal advice — check your own jurisdiction. (Dated 2026-07-08.)

How it compares

• Thymalin is the parent extract: a heterogeneous calf-thymus polypeptide mixture from the same Russian school. Thymogen is one synthetic dipeptide (Glu-Trp) derived from it — a single defined molecule, not the extract.
• Thymosin alpha-1 is a fully defined 28-amino-acid thymic peptide with a substantial independent international literature and approval in several countries — a much stronger evidentiary standing than Thymogen's.
• Epitalon is another Khavinson bioregulator and shares Thymogen's pattern: bold claims resting largely on a single research school with limited independent replication.

Common misconceptions

• "Thymogen is FDA-approved because it had an Orphan Drug designation." No. An Orphan Drug designation (ovarian cancer, Sept 2001) and IND status mark a development pathway — they are not marketing approval, which never resulted.
• "Thymogen and Thymalin are the same thing." They are not. Thymalin is the multi-peptide thymus extract; Thymogen is a single synthetic dipeptide (Glu-Trp / oglufanide) derived from it.
• "It contains glutamine." No — it is glutamyl (glutamic acid) joined to tryptophan. Some secondary sources get this wrong.
• "Russian registration means it's approved in the US/EU." It does not. A national registration is a separate decision; the molecule is not FDA- or EMA-approved.
• "The anti-cancer and anti-aging effects are proven." They are not. Those findings are animal/in-vitro or hypothesis-level, and the Western clinical programme produced no documented approval or robust Phase 3 result.