Thymogen
Also known as: Glu-Trp · L-Glu-L-Trp · EW (single-letter code) · glutamyl-tryptophan · alpha-glutamyl-tryptophan · Timogen (transliteration) · Thymogenum · IM862 (same dipeptide, Western oncology development name)
Research focus
Immune system — cellular (T-cell) immunity and host defense; studied mainly as an adjunct in secondary immunodeficiency and surgical/infection settings.
US regulatory status
Not FDA-approved · Not compoundable
Evidence rating
Emerging
Origin
Thymogen is a fully synthetic dipeptide (L-glutamyl-L-tryptophan), not an extract. Per the published record, the chemist Vladislav Deigin and colleagues at the Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry of the Russian Academy of Sciences (Moscow) fractionated thymus-gland homogenate in the 1980s, identified Glu-Trp as the most active component, and developed it into the immunostimulant drug registered in Russia as Thymogen. Notably, inverting the amino-acid chirality to the all-D form (D-Glu-D-Trp) reverses the effect, yielding the immunosuppressant Thymodepressin — a documented case of enantiomers with opposite ("reciprocal") activity. The compound was later adopted into the broader "peptide bioregulator" framework promoted by Vladimir Khavinson's group at the St. Petersburg Institute of Bioregulation and Gerontology, which lists Thymogen alongside Timalin, Vilon, Epitalon/Epithalamin and Cortexin in its geroprotector reviews. The same molecule was independently developed in the West under the name IM862 and tested as an antiangiogenic agent — a useful reminder that "Thymogen" and "IM862" denote one chemical with two very different claimed mechanisms.
Plain-language summary
Thymogen is a lab-made two-amino-acid molecule (glutamic acid joined to tryptophan) that came out of Russian thymus-peptide research in the 1980s. It is sold and used in Russia as an immune-system modulator, usually as an add-on before surgery or alongside other drugs in people with weakened immunity. The reality: there is some human data, including one small placebo-controlled trial, but almost all of it is Russian-language, comes from a narrow set of research groups, and has not been independently reproduced in large Western trials. Intriguingly, the exact same molecule was tested in the United States (as "IM862") for cancer-related uses and did not beat placebo there. None of this is a basis for treating any condition, and it is not approved in the US.
Claimed mechanism (as reported)
Published Russian work proposes that Thymogen acts as a thymus-mimetic immunomodulator that reportedly restores T-lymphocyte numbers and function and normalizes cellular-immunity markers in states of secondary immunodeficiency; some authors describe it as influencing intracellular signaling in lymphoid tissue. The chirality-dependence of the effect (L-form stimulates, D-form suppresses) is the most striking and best-characterized pharmacological observation. The precise molecular target and receptor interaction remain undefined in peer-reviewed English-language literature, and the immunomodulatory model rests largely on in-vitro lymphoid-tissue assays and single-group clinical reports. Mechanism should be regarded as proposed, not established.
Evidence summary
A small body of real human literature exists, but it is weak and concentrated. The immunomodulatory claim rests on Russian-language clinical reports, a handful of in-vitro lymphoid-tissue studies, and at least one small double-blind, placebo-controlled trial (intranasal Thymogen for preoperative preparation of elderly cancer-surgery patients) reporting improved cellular-immunity markers and fewer postoperative complications. These findings come largely from single research groups, are mostly unblinded combination studies (Thymogen plus cycloferon, mexidol, or hyperbaric oxygen), and have not been independently replicated in large peer-reviewed English-language randomized trials. Critically, the identical molecule (IM862, L-Glu-L-Trp) failed to outperform placebo in rigorous Western randomized trials — a phase III trial in AIDS-related Kaposi sarcoma and a phase II prostate-cancer study — though those tested a different (antiangiogenic) indication. No large, independently-replicated RCT supports the immunomodulatory efficacy claim as of 2026. Graded Theoretical: human data exist but are limited, single-group, and not corroborated. A multi-source review added small Russian double-blind, placebo-controlled RCTs — a post-surgical wound-healing trial (n=77) and a pediatric acute-obstructive-bronchitis immune-support trial (n=69) — plus a comparative post-cesarean endometritis study, moving Thymogen beyond purely open-label data. The trials remain small, single-region and Russian-language, and the identical dipeptide (oglufanide/IM-862) failed to show benefit in Western oncology trials. No trials are registered on ClinicalTrials.gov.
What the research reports
The First Reciprocal Activities of Chiral Peptide Pharmaceuticals: Thymogen and Thymodepressin, as Examples
Grade CDeigin V, Linkova N, Polyakova V, Volpina O et al. · International Journal of Molecular Sciences · 2020–2024
Reported finding: Documents the synthesis history: Glu-Trp was isolated from thymus homogenate and developed into the immunostimulant Thymogen (L-Glu-L-Trp), while the D-enantiomer became the immunosuppressant Thymodepressin. Confirms the L-Glu-L-Trp structure and the chirality-dependent reciprocal activity.
Sample: Not applicable (review)
Methodology: C — narrative review from the originating chemistry group; mechanistic and historical synthesis, not primary clinical evidence
Limitations: Authored by the developers; conflict of interest; emphasizes mechanism and chemistry over independently-verified clinical outcomes.
Application of Thymogen for preoperative preparation of elderly patients with tumor processes in the abdominal cavity
Grade CSmirnov VS, Petlenko SV, El'tsin SS · Advances in Gerontology (Uspekhi Gerontologii) · 2011
Reported finding: Intranasal Thymogen (reported as 100 mg once daily for 7 days pre-op) versus saline placebo reportedly restored cellular-immunity parameters and was associated with fewer and less severe postoperative complications and a shorter postoperative period.
Sample: Elderly surgical cohort (small; full n not specified in abstract)
Methodology: C — small single-center double-blind placebo-controlled RCT, Russian-language, no independent replication
Limitations: Small, single-center, single-group, Russian-language; surrogate immune markers; not independently replicated; abstract-level reporting limits appraisal.
Peptide bioregulators: the new class of geroprotectors (Message 2: Clinical studies results)
Grade CKhavinson VKh, Kuznik BI, Ryzhak GA · Advances in Gerontology (Uspekhi Gerontologii) · 2013
Reported finding: Groups Thymogen among peptide bioregulators (with Timalin, Vilon, Epithalamin, Cortexin, Prostatilen, Retinalamin) and summarizes long-term Russian clinical use for disease prevention and as geroprotectors across age groups.
Sample: Not applicable (review of multiple small studies)
Methodology: C — narrative review, single research group, English-abstract Russian-language article
Limitations: Self-citing review from the group that developed these agents; aggregates small, mostly unblinded studies; no independent meta-analysis or external replication.
Angiogenesis inhibitor IM862 (L-Glu-L-Trp) is ineffective against AIDS-Kaposi's sarcoma in a phase III trial
Grade ANoy A, Scadden DT, Lee J, Dezube BJ et al. (AIDS Malignancy Consortium) · Journal of Clinical Oncology · 2004–2005
Reported finding: The identical dipeptide (here named IM862, intranasal) showed no significant response-rate advantage over placebo for AIDS-related Kaposi sarcoma and was associated with a shorter time to progression. Included as a high-quality negative benchmark for the same molecule, albeit for an antiangiogenic rather than immunomodulatory indication.
Sample: n=202 (104 IM862, 98 placebo)
Methodology: A/B — large randomized, double-blind, placebo-controlled phase III trial (rigorous design; different indication)
Limitations: Tests a different claimed indication (antiangiogenesis, not secondary immunodeficiency); confounded by concurrent antiretroviral therapy; does not directly test the Russian immune-restoration claim but undercuts broad efficacy claims for the molecule.
Comparative effect of Thymalin and Thymogen on immunity, hemostasis and post-cesarean endometritis
Grade DAnokhova LI et al. · Meditsinskaya Immunologiya (Medical Immunology); indexed on CyberLeninka · 2011
Reported finding: Adding Thymogen (or Thymalin) to standard therapy for post-cesarean endometritis was reported to improve immune and hemostatic indices and clinical course versus standard therapy alone.
Sample: ~85 postpartum women with post-cesarean endometritis (standard n=30, +thymalin n=30, +thymogen n=30)
Methodology: D — controlled comparative study but allocation/blinding not described (not established as randomized)
Limitations: Allocation and blinding not described; single-center; surrogate immune endpoints.
Administration reported in studies
Across the Russian literature, Thymogen is most often described as given by intranasal instillation or by injection over short courses (commonly on the order of 5–10 days), and in surgical studies as a brief pre-operative course; the cited elderly-surgery RCT reported roughly 100 mcg intranasally once daily for 7 days before operation. Many reports describe it as one component of a combination regimen (for example with cycloferon, mexidol, or hyperbaric oxygenation) rather than as a standalone agent, which makes its independent contribution hard to isolate. The Western IM862 oncology trials used low-dose intranasal administration every other day. This is a summary of research conditions — not a dosing recommendation and not a protocol endorsed by TPC.
This section reports what published studies describe. It is not a dosing recommendation from TPS.
Safety record
Short-course studies and the Western IM862 trials generally reported the compound as well tolerated, with no major toxicity signals noted in the available abstracts; the Kaposi sarcoma phase III trial reported no significant toxicities, and oral/in-vitro work reported no hemolysis at tested concentrations. However, the safety database is small, the human studies are mostly short and frequently combination-based, and there is little published data on long-term use, repeated courses, pregnancy, or interactions. Absence of reported harm in small short trials is not evidence of long-term safety. TPC makes no safety assurance; reported tolerability should not be read as "safe."
US legal status
Not FDA-approved for any indication. Not on the FDA 503A compoundable bulk drug substances list, and not legally compoundable for human clinical use in the United States. Registered/marketed as a drug only in Russia and some neighboring countries, not in the US. In the US it appears only through the online "research chemical" channel — those vendors are unregulated, not verified by TPC, and selling or using the material for human consumption is outside any approved legal pathway.
Open research questions
- ? Has the immunomodulatory / T-cell-restoring effect ever been independently replicated in a large, blinded, placebo-controlled trial outside the originating Russian research groups?
- ? Given that the identical molecule (IM862) failed against placebo in rigorous Western oncology trials, what explains the divergence — true indication-specific immune effects, or publication and design bias in the Russian immunology literature?
- ? What is the actual molecular target and pharmacokinetic profile (absorption, half-life, metabolism) of L-Glu-L-Trp in humans, beyond in-vitro lymphoid-tissue assays?
- ? What are the long-term safety, repeat-course, and drug-interaction data, since nearly all human exposure has been short courses and combination regimens?
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