What Is Thymagen?

1. What is Thymagen, and where did it come from?

PubChem, the US government chemistry database, files Thymogen, Timogen and oglufanide as one compound, and lists IM862 and oglufanide disodium as its salt form (PubChem: oglufanide; PubChem: oglufanide disodium). Chemically it is a dipeptide, meaning two amino acids linked by a single peptide bond: glutamic acid at one end and tryptophan at the other.

Researchers at the St. Petersburg Institute of Bioregulation and Gerontology separated this dipeptide out of Thymalin, a peptide mixture extracted from calf thymus, and then made it synthetically as the basis of the drug (Morozov and Khavinson, 1997). A 2024 review from the same research circle says it was the most active of several tryptophan-containing dipeptides they screened from that extract (Deigin and colleagues, 2024).

How it differs from other thymus peptides

Several unrelated molecules carry thymus-derived names. They differ in size and origin, and a result for one says nothing about another.

The Khavinson group also developed other short “bioregulator” peptides, including vilon, a different synthetic dipeptide from the same group (Morozov and Khavinson, 1997), epitalon, pinealon and cartalax. Each is a distinct molecule with its own, separate evidence base.

Mirror-image forms and look-alikes

Amino acids exist in two mirror-image forms, called L and D. Thymagen uses the natural L forms of both. In mice, versions built with D-glutamic acid suppressed blood-forming stem cells, whereas the all-L form left healthy marrow alone and helped it recover after radiation (Deigin and colleagues, 2007). A D-form version was developed in Russia as a separate drug, Thymodepressin, intended to dampen immune responses rather than boost them (Deigin and colleagues, 2024).

Golotimod, also called SCV-07, shares Thymagen’s chemical formula but uses a D-glutamic acid attached through a different bond, so it is a distinct compound (PubChem: golotimod). Findings for golotimod or Thymodepressin do not describe Thymagen.

2. How is Thymagen thought to work?

No mechanism has been confirmed in people. The proposed ones come from cell and animal experiments.

• Immune cell activity. Its developers report that the dipeptide promoted T-cell maturation, altered signaling molecules inside lymphocytes, and increased the movement and microbe-engulfing activity of neutrophils, a type of white blood cell (Morozov and Khavinson, 1997).
• Natural killer cells (mouse data). In mice, the dipeptide slowed tumor growth without killing tumor cells directly. The effect disappeared in mice lacking working natural killer (NK) cells or perforin, a protein NK cells use to destroy targets (Smith and colleagues, 2003).
• Blood-vessel growth (lab and mouse data). As IM862, it was developed in the US as an angiogenesis inhibitor, a drug meant to block new blood vessels that feed tumors. An independent 2021 study found it reduced vessel sprouting in some lab and mouse assays, though a different dipeptide had stronger effects on a key growth-factor receptor (Khedr and colleagues, 2021).

These mechanisms explain why researchers expected an effect. The human trials in the next section show how far that expectation carried.

3. What did the Western clinical trials find?

Kaposi sarcoma

Kaposi sarcoma is a cancer of the cells lining blood vessels, which made it a natural first test for a drug meant to block vessel growth (Deplanque and colleagues, 2004). Two trials in people with AIDS-related disease used IM862 nasal drops.

The phase III result is the one to weigh most. Beyond the similar response rates, median time to tumor progression was 16 weeks on IM862 and 35 weeks on placebo (p = 0.012). The authors concluded the drug was not superior to placebo and might speed progression.

They also offered an explanation for the earlier, more encouraging trial. Nearly all participants were taking HIV combination therapy, which by itself produced lasting tumor responses and could have inflated the response rate seen without a placebo group. A 2022 systematic review of Kaposi sarcoma treatments found too little evidence to recommend any specific intervention.

Kidney, prostate and other cancers

In the kidney cancer trial, blood levels of VEGF, a growth signal for blood vessels, fell at weeks 4 and 8. A falling marker without tumor control shows why a lab signal is not the same as a clinical benefit.

Registered trials in ovarian and colorectal cancer have no published results that we could find. One colorectal trial was terminated with the stated reason “Drug not available” (NCT00006037; see also NCT00003773 and NCT00017303).

4. What do the Russian clinical reports say?

Russian clinical papers on Thymogen go back to at least the early 1990s, and its developers have reviewed its use for prevention and treatment across age groups (Khavinson, Kuznik and Ryzhak, 2013). Most reports are short and in Russian, and their English abstracts often omit patient numbers or effect sizes.

The gastritis study is the most detailed of these, and it measured tissue, not symptoms or long-term outcomes. Across the Russian literature, outcomes are mostly immune cell counts or other surrogate markers, and we found no independent replication outside Russia.

5. What do the animal studies show?

All of the following come from animals, mostly in studies by the developers’ own groups.

The rat result is sometimes cited as an anti-aging effect. Average life span did not change; only the longest-surviving tail of the group shifted. None of these findings has been shown to carry over to people.

6. Is Thymagen approved or legal?

• Russia. Its developers state it is registered with the Russian Ministry of Health under a certificate dated June 10, 2009 (Deigin and colleagues, 2024).
• United States and European Union. There is no FDA or EMA approval. The IM862 cancer program did not lead to approval, and one randomized colorectal trial ended because the drug was not available (NCT00006037).
• Sport. The compound is not named on the 2026 WADA Prohibited List. The list’s S0 class bans unlisted substances that lack current approval from any government health regulator for human use. Because Thymogen is registered in Russia, it is unclear whether S0 covers it, and we found no WADA ruling on it specifically.

Outside Russia, vials or nasal sprays sold as “Thymagen” are not regulated medicines. Their identity, purity, strength and, for injectables, sterility have not been independently verified.

7. What doses have been studied, and what is its half-life?

The only doses with published trial outcomes outside Russia come from the IM862 cancer studies. These were nasal drops of 5 mg on alternating schedules in Kaposi sarcoma (Tulpule and colleagues, 2000; Noy and colleagues, 2005) and 20 mg three times daily in kidney cancer (Deplanque and colleagues, 2004). These regimens were tested against cancer and did not work; they are not evidence of an effective dose for any other purpose.

We found no published study measuring the absorption, half-life or elimination of this dipeptide in humans. Chemists trying to make an oral version described IM862 as highly water-soluble but poorly able to cross membranes such as the gut wall, which makes it “not orally available” (Bergeon and Toth, 2007). That is why the Western trials used nasal drops.

Without measured bioavailability or half-life, a half-life curve for Thymagen would rest entirely on an assumed number. Half-life figures quoted on product pages are not based on published human data.

8. What are the side effects and risks?

What the trials reported

The Western trials, all using nasal drops, reported little toxicity:

• In the Kaposi sarcoma schedule study, side effects were mild and brief: headache, fatigue, tingling and nausea, with no blood-count problems attributed to the drug (Tulpule and colleagues, 2000).
• In the kidney cancer trial, none of the 24 people evaluable for safety had a drug-related grade 2 or 3 toxicity (Deplanque and colleagues, 2004).
• In the prostate cancer trial, no significant toxicities emerged (Mao and colleagues, 2007).

Possible harm in cancer

Few side effects is not the same as safe. In the phase III Kaposi sarcoma trial, tumors progressed sooner on IM862 than on placebo, a median of 16 versus 35 weeks, and the authors could not exclude that the drug accelerated progression (Noy and colleagues, 2005).

What has not been studied

Long-term safety, use in pregnancy or breastfeeding, and drug interactions have not been reported in the indexed literature. Thymagen is described as an immune stimulant, and its effects in people with autoimmune disease or those taking immunosuppressive drugs have not been tested in published trials.

9. Thymagen, GLP-1 medicines and what you can track

No published study has combined Thymagen with semaglutide, tirzepatide or any other GLP-1 medicine. There are no interaction data, and nothing in the trials above measured body weight, appetite, blood sugar or muscle. If muscle preservation during GLP-1 treatment is the concern, the evidence summarized in the GLP-1 muscle loss guide is a better starting point; this compound has no data there.

The Russian reports mostly measured immune cell counts. A change in a white-cell number on a routine blood test cannot show that Thymagen worked, because such counts shift with infections, sleep, stress and other medicines, and no trial has linked a particular count change to a clinical benefit.

If someone is already using it, a log can still help a clinician understand a timeline. Recording the product name, source, route, dates, any new symptoms and any changes to other medicines keeps that history usable; the peptide tracking guide covers practical ways to do this. A log cannot turn an unverified product into a studied one, and starting several compounds at once makes it impossible to tell which one caused a change.

10. Thymagen FAQ

• Is Thymagen the same as Thymogen?

  Yes. Thymagen, Thymogen and Timogen are spellings of the same trade name. The compound's international nonproprietary name is oglufanide, and its disodium salt was studied in US and UK cancer trials under the code IM862.

• Is Thymagen the same as Thymalin?

  No. Thymalin is a mixture of peptides extracted from calf thymus. Thymagen is a single synthetic dipeptide that researchers isolated from that extract. Evidence for one cannot be assumed to apply to the other.

• Is Thymagen FDA approved or legal?

  It is not approved by the FDA or the EMA. Its developers state it is registered with the Russian Ministry of Health. Outside Russia, products sold under the name are not regulated medicines, and their identity and purity are not independently checked.

• What are the side effects of Thymagen?

  In Western cancer trials using nasal drops, reported side effects were mild and short-lived, such as headache, fatigue, tingling and nausea. In the phase III Kaposi sarcoma trial, tumors progressed sooner on the drug than on placebo. Long-term safety, pregnancy data and interactions have not been reported.

• How long does Thymagen stay in your system?

  No published human study has measured its absorption, half-life or elimination. Numbers on vendor pages have no published human study behind them, so any estimate of how long it stays in the body is unsupported.

• Can Thymagen be used with semaglutide or tirzepatide?

  No study has tested Thymagen alongside semaglutide, tirzepatide or any GLP-1 medicine, and no drug-interaction data have been published. Anyone considering combining them should discuss it with the prescriber of their GLP-1 treatment.

• Does Thymagen boost the immune system?

  Laboratory and animal studies, mostly from its developers, report effects on T cells, neutrophils and natural killer cells. Russian clinical reports describe fewer infections and complications, but most abstracts lack patient numbers and effect sizes. A benefit for healthy people's immunity has not been shown.

• Is Thymagen banned in sport?

  It is not named on the 2026 WADA Prohibited List. WADA's S0 class covers substances without current government approval for human therapeutic use; because Thymogen is registered in Russia, whether S0 applies is unclear, and no WADA ruling specific to it was found.

11. Sources