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Ta15.0
Thymosin Alpha-1 Research
Mostly mechanism / observationalModerate safety
14 peer-reviewed studies
What the evidence says
Mostly mechanism / observational
Most Thymosin Alpha-1 studies are mechanism or observational rather than RCTs that measure a clinical effect — keep findings provisional.
Most evidence is from medium-quality meta-analyses and randomised trials published 1999–2025 with a typical study size of 316 participants.
Based on 14 studies · 9 meta-analyses · 4 RCTs · 851 total participants
Confidence
High
By outcome
Immune support
Mostly mechanism / observational7 studies
Hepatitis & liver
Mostly mechanism / observational4 studies
Respiratory & lung
Mostly mechanism / observational3 studies
Safety profile
Mostly mechanism / observational3 studies
Steady research
4 studies in the last 5 years · Latest meta-analysis: 2025
199920122025
1RCTn=316 · medium study2005
Talpha1 at doses of 0.8 and 1.6 mg exhibits long-term efficacy against hepatitis B with a good safety profile.
Iino S, Toyota J, Kumada H, Kiyosawa K, Kakumu S, Sata M, Suzuki H, Martins EB. · J Viral Hepat (2005)
316 chronic hepatitis B patients randomized to 0.8 or 1.6 mg Tα1 monotherapy for 24 weeks
At 72 weeks (12 months after stopping), the 1.6-mg group reached 36.4% ALT normalization, 30% HBV-DNA clearance and 22.8% HBeAg clearance
Patients with advanced fibrosis responded better at 1.6 mg than 0.8 mg
The use of Tα1 therapy in combination with conventional medical therapies may be effective in improving clinical outcomes in a targeted population of severe sepsis.
Wu J, Zhou L, Liu J, Ma G, Kou Q, He Z, Chen J, Ou-Yang B, Chen M, Li Y, Wu X, Gu B, Chen L, Zou Z, Qiang X, Chen Y, Lin A, Zhang G, Guan X. · Crit Care (2013)
ETASS: the pivotal multicenter RCT — 361 severe-sepsis patients across six Chinese teaching hospitals randomized 1:1 to Tα1 or control
28-day all-cause mortality 26.0% (Tα1) vs 35.0% (control); relative risk 0.74 (95% CI 0.54-1.02) — a borderline result (nonstratified P = 0.062; log-rank P = 0.049)
Tα1 produced greater recovery of monocyte HLA-DR (an immune-restoration marker) on days 3 and 7, consistent with its immunomodulatory mechanism
Tα1 has the potential to decrease 28-day mortality rates in patients with sepsis; however, it is crucial to recognize that its efficacy differs among various subgroups.
Gu B, Zhou Y, Nie Y, Wang L, Liang L, Liao Z, Wen J, Guan X, Chen M, Wu J, Pei F. · Front Cell Infect Microbiol (2025)
Overall 28-day mortality was reduced (OR 0.73, 95% CI 0.59-0.90) — but the benefit DISAPPEARED in the high-quality subgroup (OR 0.82, 0.65-1.03) and the multicenter subgroup (OR 0.86, 0.68-1.08)
Trial sequential analysis indicated the pooled sample size is still inadequate to confirm benefit; subgroup signals (cancer, diabetes, coronary disease) were low-to-moderate credibility
ETV plus Tα1 might lead to a higher clinical response and a lower comprehensive adverse reaction rate in HBV-related patients with cirrhosis, compared to ETV alone.
Peng D, Xing HY, Li C, Wang XF, Hou M, Li B, Chen JH. · BMC Gastroenterol (2020)
Seven RCTs, 1144 subjects with HBV-related cirrhosis
Entecavir + Tα1 gave higher complete response (RR 1.18) and higher HBV-DNA-undetectable and HBeAg-loss rates at 24 weeks versus entecavir alone
Differences were not significant at 48-52 weeks, and HBsAg loss was unchanged — benefit attenuates over time
There was a trend towards HBeAg loss when using combination therapy... This could clinically indicate a potential important difference that would need confirmation in subsequent trials.
Lim SG, Wai CT, Lee YM, Dan YY, Sutedja DS, Wee A, Suresh S, Wu YJ, Machin D, et al. · Antivir Ther (2006)
Double-blind RCT, 98 HBeAg-positive chronic hepatitis B patients; Tα1 + interferon versus interferon + placebo for 24 weeks
HBeAg loss at 72 weeks 45.8% (combination) vs 28.0% (monotherapy) — a 17.8% difference that did NOT reach significance (95% CI -1.2% to 35.3%, P = 0.067)
No significant differences in HBeAg seroconversion, histology, ALT normalization or HBV-DNA loss
6Meta-Analysis2016
Thymosin α1 alone was associated with significantly lower 28-day mortality... but there was no significant difference in the 90-day mortality.
Feng Z, Shi Q, Fan Y, Wang Q, Yin W. · J Trauma Acute Care Surg (2016)
12 studies in severe sepsis comparing ulinastatin and/or Tα1 immunomodulatory therapy
Tα1 alone reduced 28-day mortality (RR 0.72, 95% CI 0.55-0.93) but NOT 90-day mortality (RR 0.84, 95% CI 0.54-1.31) — GRADE rating low/very low for Tα1 alone
Combination (ulinastatin + Tα1) reduced both 28- and 90-day mortality (moderate GRADE)
Interferon and thymosin alpha-1 combination therapy achieves superior effect with no increase in the adverse effects as compared to interferon monotherapy for HBeAg positive chronic hepatitis B.
Mao HY, Shi TD. · Zhonghua Gan Zang Bing Za Zhi (2011)
Seven RCTs, 535 HBeAg-positive chronic hepatitis B patients
Combination was more effective than interferon alone for HBV-DNA-negative rate, ALT normalization, HBeAg loss and seroconversion, both at end of treatment and follow-up
HBsAg loss rate higher with combination only at end of follow-up
Our study suggests that treatment with thymosin alpha-1 may reduce mortality rate in moderate to critical COVID-19 patients. Randomized clinical trials (RCTs) are still required to verify the findings.
Thymosin alpha1 was well absorbed with a mean t(max) between 1-2 hours from all galenic formulations... the short elimination half-life of less than 3 hours.
Randomized 3-way crossover PK study in 9 healthy volunteers comparing three subcutaneous formulations (including Zadaxin)
Well absorbed subcutaneously (Tmax 1-2 h), short elimination half-life <3 h, no accumulation on repeat dosing
Distribution within extracellular volume; AUC/Cmax differed by formulation
14Meta-Analysis2011
Overall, we found neither evidence that the addition of pTE to antineoplastic treatment reduced the risk of death or disease progression nor that it improved the rate of tumour responses to antineoplastic treatment.
Wolf E, Milazzo S, Boehm K, Zwahlen M, Horneber M. · Cochrane Database Syst Rev (2011)
Cochrane systematic review and meta-analysis of 26 randomized trials (2736 patients) of purified thymus extracts (pTE) and synthetic thymic peptides (sTP, including thymopentin and thymosin-alpha-1) added to chemo/radiotherapy in cancer
Adding thymic peptides did NOT reduce risk of death or disease progression, nor improve tumour-response rate (e.g. pTE overall survival RR 1.00, 95% CI 0.79-1.25)
Only a trend toward benefit for thymosin-alpha-1 specifically, and a reduced risk of severe infectious complications with purified thymus extract