TB-500 South Asian Documented Efficacy Gaps: Pharmacogenomics, Dosing, and What the Evidence Actually Shows

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Does TB-500 work differently in South Asian patients?

There is no result to compare. FDA's evaluation, prepared for the July 2026 Pharmacy Compounding Advisory Committee meeting, found no article in which TB-500 was administered to a human, and none of the three papers the nominator submitted involved TB-500 in humans [1]. Because TB-500's effect has not been measured in people, a South Asian-specific difference cannot be established or ruled out.

What exists for TB-500 is thin even in animals. FDA found no in-vivo animal study of TB-500 for wound healing, and an in-vitro scratch-wound test found that TB-500 at 50 microgram/mL did not induce wound closure in fibroblast cultures; a shorter metabolite, N-acetylated LKKTE, did show activity in that assay [1].

What TB-500 is, and which trials do not answer the question

TB-500 is a synthetic, N-acetylated 7-amino-acid fragment of thymosin beta-4 (residues 17 to 23, Ac-Leu-Lys-Lys-Thr-Glu-Thr-Gln-OH), with a molecular weight of about 889 g/mol. It is not the full 43-amino-acid protein and not thymosin alpha-1 [1]. FDA found several salts and derivatives, including different active moieties, sold under the same name [1].

Published human studies of thymosin beta-4 tested full-length recombinant protein or thymosin beta-4 eye drops, not TB-500. A separate retrospective knee-pain report involved BPC-157 alone or combined with thymosin beta-4, but the form was not specified and the study cannot show that TB-500 works [1][3].

• A phase 1 study in 54 healthy Chinese volunteers gave single intravenous doses of recombinant human thymosin beta-4 from 0.05 to 25 microgram/kg across seven cohorts, and 30 more volunteers received 0.5, 2 or 5 microgram/kg daily for 10 days. Adverse events were mild to moderate, with no dose-limiting toxicity or serious adverse events [4].
• A phase 2 dry-eye trial randomized 72 adults to 0.1% thymosin beta-4 eye drops or placebo for 28 days. Neither primary endpoint, ocular discomfort or inferior corneal staining, differed significantly, though several secondary endpoints did [5].
• A smaller phase 2 trial treated 9 patients with severe dry eye; at day 56 the treated group (12 eyes) had a 35.1% reduction in ocular discomfort and a 59.1% reduction in total corneal staining versus vehicle (6 eyes) [6].
• A randomized trial in 96 patients with STEMI after angioplasty found a smaller infarct area at 90 days only in the subgroup given the first dose within 8 hours (n=43); the overall difference across all 96 was not significant [7].

None of these results establish what TB-500 does in anyone.

What is actually documented about South Asian populations

South Asian studies document differences in diabetes and cardiovascular risk, but they do not establish a TB-500 efficacy difference or a South Asian-specific dose [8][9][10]. South Asians typically develop type 2 diabetes 5 to 10 years earlier and at a lower BMI than white Europeans, and appear more insulin resistant across the life course [8]. In MASALA and MESA, age-adjusted diabetes prevalence was 23% in 799 South Asians versus 6% in 2,611 white participants, with higher HOMA-IR and lower HOMA-beta in South Asians after adjustment for age and adiposity [9]. In a case-control study at 15 centers in 5 South Asian countries, mean age at first myocardial infarction was 53.0 years, versus 58.8 years in other countries [10]. Higher insulin resistance and earlier coronary disease describe the population; they do not show that a drug behaves differently in it.

Would body composition or kidney function change exposure?

For TB-500 there is no measurement to adjust. FDA found no human pharmacokinetic or pharmacodynamic data by any route and no nonclinical toxicity studies [1]. Animal work indicates that subcutaneous or intraperitoneal TB-500 reaches the bloodstream and is hydrolyzed into smaller peptides; FDA found no animal studies using intramuscular injection [1]. Without a human clearance value, there is no parameter to stratify by body composition, eGFR or ancestry.

Dosing

There is no approved dose and no human dosing study [1]. The nomination FDA reviewed proposed a 3 mg/mL lyophilized powder for subcutaneous or intramuscular injection [1]. Seller protocols are not dosing evidence. Doses used in trials of full-length recombinant thymosin beta-4, such as 0.05 to 25 microgram/kg intravenously in the phase 1 study [4], describe a different molecule and do not transfer to TB-500.

What is known about safety in people

Very little. FDA's search of its adverse-event database through March 26, 2025 retrieved no TB-500 reports, and its food and supplement complaint system returned two cases involving a blended TB-500 and BPC-157 product with no safety assessment; FDA found no published case reports [1]. Safety in humans is unknown [1].

FDA's BPC-157 review describes a 40-year-old woman who injected a research-purpose BPC-157 plus TB-500 product (5 mg/5 mg) subcutaneously twice daily and developed widespread skin hyperpigmentation and gum darkening within a week, recurring when she used it again two weeks later; because the product held two peptides, FDA said it could not tell which caused it [11]. FDA's stated concern for injectable TB-500 is immunogenicity, potentially amplified by peptide aggregation and impurities [1].

Regulatory status and sport

TB-500 is not an FDA-approved drug [1]. FDA staff recommended against adding it to the pharmacy bulks list, citing no human data, unclear historical use, no evidence of effectiveness for wound healing, immunogenicity risk, and the availability of approved wound treatments [1]. The Pharmacy Compounding Advisory Committee voted in favor of adding it on July 23, 2026; that advice is not binding and TB-500 is not on the list [12][13]. HHS's draft enforcement-discretion policy for certain peptides, filed October 28, 2026, names TB-500 acetate for subcutaneous or intramuscular injection and says HHS does not intend to take enforcement action against certain state-licensed pharmacies, federal facilities and licensed physicians if its conditions are met; it is not an approval and does not place TB-500 on any list [13][14].

TB-500 also appears in none of the three categories on FDA's interim policy lists for state-licensed pharmacies or outsourcing facilities [15][16][17]. It sits in the 'nominated but withdrawn' table of FDA's safety-risk page, which holds substances previously in category 2 whose nominators withdrew them; that was not a safety finding [18]. WADA names 'Thymosin-beta4 and its derivatives e.g. TB-500' in section S2.3, prohibited at all times in and out of competition, on both the 2026 and 2027 Lists [2][19].