What it is
Thymogen is two amino acids long. It is the dipeptide L-glutamyl-L-tryptophan — glutamic acid joined to tryptophan, written Glu-Trp — and PubChem lists it under its international non-proprietary name, oglufanide. It is about as small as a peptide can be.
It belongs to the same Russian tradition as thymalin, the calf-thymus extract, and the two are connected by chemistry: research on which parts of thymalin do the work points to short dipeptides, and one of them, written EW, is Glu-Trp. Where thymalin is a mixture, thymogen is the opposite approach — one short fragment, made synthetically, the same molecule in every batch. It has appeared in Russian journals since at least 1992 as an immunomodulator, a drug meant to adjust immune function, used around surgery and in infections.
The same molecule under two names
This entry has one finding that is easy to miss and changes the whole picture.
Searched as "thymogen", ClinicalTrials.gov returns nothing. That looks like the pattern of semax and thymalin: a Russian medicine with decades of use and no presence on the international registry.
Searched as "oglufanide", the registry returns three trials — all run in the United States between 1999 and 2001, under the development code IM862, by a company called Cytran: two in ovarian cancer and one in colorectal cancer. And the published record under IM862 holds something the Russian literature does not: a large, placebo-controlled trial.
PubMed shows the split plainly. 103 records under thymogen and 12 under IM862 — and here the two systems behave differently. PubMed maps both names to one substance record, so 7 of the IM862 papers also appear in a thymogen search. The trial registry does no such mapping. A reader checking the registry by the familiar name finds nothing and concludes the molecule was never tested; it was, in 202 people.
What the American trials found
In the United States, IM862 was tested not as an immune booster but as an angiogenesis inhibitor — a drug meant to stop tumours building the blood vessels they feed on — in Kaposi's sarcoma, a cancer common in people with advanced HIV.
The early result looked strong. A 44-patient phase 2, published in the Journal of Clinical Oncology in 2000, gave 5 mg as nasal drops and reported major responses in 36% of patients, with only mild, transient side effects. It had no control group.
The phase 3 did not hold up. In 202 patients randomised to IM862 or placebo (Journal of Clinical Oncology, 2005):
| IM862 | Placebo | |
|---|---|---|
| Patients | 104 | 98 |
| Response rate | 23% | 21% |
| Median time to progression | 16 weeks | 35 weeks |
Responses were the same. The disease progressed sooner on the drug. The authors' explanation is the most useful sentence in the file: almost every patient was also on highly active HIV treatment, which shrinks Kaposi's sarcoma by itself, and that treatment "may have contributed to prior estimates" of the drug's effect. The uncontrolled trial had measured the HIV drugs.
What the Russian record holds
In Russia thymogen is prescribed, and its literature is clinical. 59 of the 103 PubMed records carry a human tag, but most are small reports without a control group, written in Russian. The strongest-designed one found is a double-blind, placebo-controlled study in elderly patients before surgery for abdominal tumours (Advances in Gerontology, 2011), which reports that thymogen helped restore measures of cellular immunity. It is available as a Russian-language abstract only, and it measured immune cells, not infections or survival.
That is the honest shape of the evidence: a molecule with one large, rigorous trial — in a use it failed — and a long clinical tradition in another use that has never been tested the same way.
Where it stands
Not approved in the United States; Drugs@FDA returned nothing under thymogen, oglufanide or IM862 on 2026-09-23. The three registered trials are all from 1999–2001. The Russian clinical use continues outside the international registry.
Related reading
Thymalin, the thymus extract from the same programme, and thymosin alpha-1, the single defined thymus peptide with an international trial record. For the category, see peptides for immunity. Semax is the other Russian medicine in this library whose registry record depends on which name is searched.