Immune
Thymosin Alpha-1
Also known as Thymalfasin, Zadaxin
Thymic peptide approved in several countries outside the U.S. for hepatitis B and as an immune adjuvant.
Where the evidence comes from
75 verified records from 16 countries. The number of studies or countries is not proof that Thymosin Alpha-1 works or is safe.
Human clinical trial: 26 · Randomized clinical trial: 10 · Systematic review / meta-analysis: 4 · Narrative review: 17 · Observational human study: 3 · Animal study: 15
What is known
Editorial summary not yet written.
What remains uncertain
Editorial summary not yet written.
Conflicting findings
Editorial summary not yet written.
U.S. regulatory status (FDA)
Compound
Product or formulation
FDA status
FDA-approved branded drug
Approved indication
Metara availability (compounded formulation)
Research material (research use only)
Source
Last verified
Notes
Approval applies only to the exact finished drug, formulation and indication. A shared active ingredient does not make a compounded version, blend or other use FDA-approved. Pharmacy or research-material availability is not FDA approval.
International regulatory status
Kept separate from U.S. status. The regulator's country is not the same as where studies took place.
No sourced international decisions recorded yet.
Continue your research
These are two different pathways, not two ways to get the same thing. Neither changes the FDA status shown above.
Clinical care
Available through Metara Health
Explore clinician-guided care and available pharmacy options.
EXPLORE METARA HEALTH →Limitations
Human trials largely conducted outside the U.S.; results vary by condition.
Human clinical evidence (39)
Neoadjuvant immunochemotherapy plus thymalfasin in locally advanced gastric cancer: a prospective clinical trial
Xu H, Li F, Li B, Yang D, Liu T, Xia Y, Hua H, Li Q, Wang J, Liu H, Xu Z · BMC medicine · DOI 10.1186/s12916-026-04740-z
This human trial tested thymalfasin with immunotherapy and chemotherapy before surgery for locally advanced stomach or gastroesophageal junction cancer. The combination produced encouraging tumor responses and clearance of cancer from lymph nodes, with safety described as acceptable despite some severe adverse events. Immune findings suggest thymalfasin may help coordinate antitumor immunity, but larger randomized trials are needed.
Thymosin-α1 for Recurrent Implantation Failure Following Transfer of PGT-a Tested Embryo: A Randomized, Double-Blind, Placebo-Controlled Trial
Fakih IVF Fertility Center · ClinicalTrials.gov · NCT07675980
This recruiting randomized, double-blind, placebo-controlled human trial is evaluating thymosin alpha-1 in women with unexplained repeated embryo implantation failure undergoing fertility treatment. It is assessing safety and effectiveness as an added immune-modulating therapy. No results are reported.
Efficacy and Safety Study of Thymalfasin in Combination with Targeted Immunotherapy (Regorafenib and Tislelizumab) in Patients with Advanced PMMR/MSS Colorectal Cancer Who Failed Standard of Care: a Multicenter, Open-label, Randomized, Controlled Clinical Study
Beijing Friendship Hospital · ClinicalTrials.gov · NCT06829355
This recruiting randomized human trial is testing whether adding thymalfasin to regorafenib and tislelizumab improves safety and effectiveness in advanced pMMR/MSS colorectal cancer after standard care has failed. It compares the combination with and without thymalfasin. No results are reported.
Efficacy and Safety of Thymosin α1 Plus Immune Checkpoint Inhibitors and Chemotherapy as Neoadjuvant Therapy in Patients With Resectable Stage II - IIIB Non Small Cell Lung Cancer: A Prospective, Multicenter, Randomized, Controlled Trial
Xuanwu Hospital, Beijing · ClinicalTrials.gov · NCT06607926
This registered human trial plans to assess the safety and effectiveness of thymosin alpha-1 combined with chemotherapy and PD-1 immune checkpoint inhibitors before surgery in people with operable non-small cell lung cancer. It has not yet begun recruiting, and no results are reported.
Phase I/II Clinical Study to Evaluate the Safety, Tolerability, and Preliminary Efficacy of Local Administration of Recombinant Oncolytic Adenovirus Injection (KD01) in Patients With Gynecologic Malignancies
Tongji Hospital · ClinicalTrials.gov · NCT06552598
This human trial studies the safety, tolerability, and early effectiveness of KD01, an engineered cancer-killing virus, in people with gynecologic cancers, including cervical and endometrial cancer. It also plans to examine immune effects and how KD01 kills tumor cells. The trial is recruiting, and no results are reported.
Assessment of the Efficacy of Immunomodulatory Therapy With Thymosin Alpha 1 (Tα1) Following Surgical Resection in Patients With Stage I Non-Small Cell Lung Cancer
Yousheng Mao · ClinicalTrials.gov · NCT06598839
This human trial examines thymosin alpha 1 after surgery for stage I non-small cell lung cancer, focusing on tumor cells circulating in the blood and age-related decline in immune function. It is recruiting participants, and no results are reported.
A Prospective and Randomized Control Study on Effects of Thymalfasin for Injection on Perioperative Immune Function and Long-term Prognosis of Patients with Colorectal Cancer
Niu W, Li Z, Li Z, Hu X, Wang X, Ding Y, Li C, Yu B · Biotechnology & genetic engineering reviews · DOI 10.1080/02648725.2023.2216972
This randomized human study compared chemotherapy with or without thymalfasin in people undergoing colorectal cancer surgery. The thymalfasin groups had fewer infections and postoperative complications, better immune-function measures, lower local recurrence and distant spread, and longer survival without disease. These findings were reported in comparison with chemotherapy alone.
A pilot trial of Thymalfasin (Ta1) to prevent covid-19 infection and morbidities in renal dialysis patients: Preliminary report
Tuthill CW, Awad A, Parrigon M, Ershler WB · International immunopharmacology · DOI 10.1016/j.intimp.2023.109950
This preliminary randomized human trial report examined thymalfasin for preventing COVID-19 and reducing its severity in people receiving hemodialysis. Fewer deaths and COVID-19-related serious adverse events had been reported in the thymalfasin group than in controls, but these were preliminary observations. The study was nearing completion, with final safety, effectiveness, and antibody analyses still pending.
Systematic & narrative reviews (21)
Thymosin alpha 1 alleviates inflammation and prevents infection in patients with severe acute pancreatitis through immune regulation: a systematic review and meta-analysis
Tian Y, Yao J, Ma Y, Zhang P, Zhou X, Xie W, Tang W · Frontiers in immunology · DOI 10.3389/fimmu.2025.1571456
This systematic review combined randomized human trials of thymosin alpha-1 in severe acute pancreatitis. It found improvements in some immune-cell measures and fewer infections outside the pancreas, but no significant reduction in lung infections or hospital stay. The authors concluded that thymosin alpha-1 may reduce inflammation and help prevent infections, with further research needed.
Aging and Thymosin Alpha-1.
Simonova MA, Ivanov I, Shoshina NS, Komyakova AM, Makarov DA, Baranovskii DS, Klabukov ID, Telepenina KP, Atiakshin DA, Shegay PV, Kaprin AD, Stepanenko VN · International journal of molecular sciences · DOI 10.1016/j.jpet.2025.103752
This review discusses thymosin alpha-1 and age-related immune decline, drawing on preclinical research and human clinical studies. It reports that thymosin alpha-1 can improve vaccine responses in older adults and reduce age-related deterioration in immune function. Longer-term effectiveness and safety in older adults still need validation.
Phenotypic drug discovery: a case for thymosin alpha-1
Garaci E, Paci M, Matteucci C, Costantini C, Puccetti P, Romani L · Frontiers in medicine · DOI 10.3389/fmed.2024.1388959
This review discusses thymosin alpha-1 research in preclinical settings and humans as an example of discovering drugs by observing their effects rather than starting with a known molecular target. It explores how this approach could fit precision medicine. The abstract does not report specific efficacy or safety findings.
PD-1 inhibitor combined with SBRT, GM-CSF, and thymosin alpha-1 in metastatic breast cancer: A case report and literature review
Yu J, Wang Q, Wang L, Zong D, He X · Medicine · DOI 10.1097/md.0000000000039271
This case report described a woman with previously treated metastatic triple-negative breast cancer who received radiation, immunotherapy, an immune-cell growth factor, and thymosin alpha-1. The combined regimen produced a partial tumor response, including shrinkage outside the irradiated area. A skin reaction improved with treatment; the report does not establish thymosin alpha-1's separate contribution.
Thymosin Alpha 1 Plus Routine Treatment for the Acute Exacerbation of Chronic Obstructive Pulmonary Disease: A Systematic Review and Meta-Analysis
Cao A, Feng F, Zhou X · Journal of the College of Physicians and Surgeons--Pakistan : JCPSP · DOI 10.29271/jcpsp.2024.12.1497
This systematic review combined randomized human trials of thymosin alpha-1 added to routine care during acute worsening of chronic obstructive pulmonary disease. Compared with routine care alone, it improved lung function, blood oxygen and carbon dioxide measures, and immune-cell measures, and shortened hospital stays. The authors called for higher-quality trials to confirm effectiveness.
Comprehensive Review of the Safety and Efficacy of Thymosin Alpha 1 in Human Clinical Trials
Dinetz E, Lee E · Alternative therapies in health and medicine · PMID 38308608
This narrative review examined human clinical studies of thymosin alpha-1 for COVID-19, other infections, autoimmune conditions, and cancer. The authors reported consistent evidence of safety and effectiveness across the conditions reviewed and concluded that thymosin alpha-1 was a well-tolerated, effective regulator of immune responses.
The efficacy of thymosin alpha-1 therapy in moderate to critical COVID-19 patients: a systematic review, meta-analysis, and meta-regression
Soeroto AY, Suryadinata H, Yanto TA, Hariyanto TI · Inflammopharmacology · DOI 10.1007/s10787-023-01354-2
This systematic review combined studies of thymosin alpha-1 in people with moderate to critical COVID-19. Its use was associated with lower mortality, but there was no significant difference in the need for mechanical ventilation or length of hospital stay compared with placebo. The authors concluded that it may reduce mortality, but randomized trials are needed to verify the findings.
Thymosin alpha 1: a comprehensive review of the literature
Dominari A, et al. · World Journal of Virology
This comprehensive review covered the literature on thymosin alpha 1; the title does not specify particular conditions, populations, or experimental models. The abstract was not available, so results are not summarized.
Laboratory, animal & other research (15)
Thymosin alpha 1 as an adjuvant to hyperthermic intraperitoneal chemotherapy in an experimental model of peritoneal metastases from colonic carcinoma
Nevo N, Lee Goldstein A, Bar-David S, Natanson M, Alon G, Lahat G, Nizri E · International immunopharmacology · DOI 10.1016/j.intimp.2022.109166
This animal study tested thymosin alpha-1 added to heated abdominal chemotherapy in mice with colon cancer spread within the abdomen. The combination increased survival compared with chemotherapy alone and sham treatment. Thymosin alpha-1 promoted an antitumor immune response and immune-cell entry into tumors, but did not directly inhibit tumor-cell growth.
Immunopotentiator thymosin alpha-1 attenuates inflammatory pain by modulating the Wnt3a/β-catenin pathway in spinal cord
Huang J, Jiang H, Pan M, Jiang Y, Xie L · Neuroreport · DOI 10.1097/wnr.0000000000001370
This animal study examined thymosin alpha-1 in experimentally induced inflammatory pain. It reduced sensitivity to touch and heat, lowered inflammatory signals, and reversed activation of the Wnt3a/β-catenin pathway in the spinal cord. The authors suggest that its pain-reducing effects might be related to reduced inflammatory signals.
Thymosin Alpha-1 Inhibits Complete Freund's Adjuvant-Induced Pain and Production of Microglia-Mediated Pro-inflammatory Cytokines in Spinal Cord
Xu Y, Jiang Y, Wang L, Huang J, Wen J, Lv H, Wu X, Wan C, Yu C, Zhang W, Zhao J, Zhou Y, Chen Y · Neuroscience bulletin · DOI 10.1007/s12264-019-00346-z
This animal study examined thymosin alpha-1 in experimentally induced inflammatory pain. It reduced pain hypersensitivity and inflammatory signaling proteins in inflamed skin and the spinal cord. It also reversed activation of microglia, immune cells in the nervous system, suggesting a role in regulating inflammatory pain.
Fusion of thymosin alpha 1 with mutant IgG1 CH3 prolongs half-life and enhances antitumor effects in vivo
Shen X, Wang L, Xu C, Yang J, Peng R, Hu X, Wang F, Zheng H, Lao X · International immunopharmacology · DOI 10.1016/j.intimp.2019.05.047
This animal study tested a modified thymosin alpha-1 joined to an antibody fragment to make it last longer in the body. The modified protein lasted longer and inhibited tumor growth more effectively than unmodified thymosin alpha-1 in animal tumor models. It also increased tumor-associated immune cells and production of certain immune-signaling proteins.
Immunopotentiator Thymosin Alpha-1 Promotes Neurogenesis and Cognition in the Developing Mouse via a Systemic Th1 Bias
Wang G, He F, Xu Y, Zhang Y, Wang X, Zhou C, Huang Y, Zou J · Neuroscience bulletin · DOI 10.1007/s12264-017-0162-x
This animal study examined thymosin alpha-1's effects on brain development and cognition in newborn mice. Treated mice showed better cognitive performance, increased markers of new brain-cell formation, and protection against impaired nerve-cell formation caused by a bacterial component. The findings suggest these effects probably involve a shift toward a particular immune response.
Evaluation of thymosin α 1 in nonclinical models of the immune-suppressing indications melanoma and sepsis.
King RS, Tuthill C · Expert opinion on biological therapy · DOI 10.1517/14712598.2015.1008446
These pilot animal studies tested thymosin alpha 1 in mouse models of melanoma and sepsis. Treatment significantly reduced lung metastases and tumor growth in the melanoma models, while the sepsis model showed a positive trend toward improved survival and lower bacterial burden. No evidence of toxicity was observed.
Thymosin alpha 1: from bench to bedside.
Garaci E, Favalli C, Pica F, Sinibaldi Vallebona P, Palamara AT, Matteucci C, Pierimarchi P, Serafino A, Mastino A, Bistoni F, Romani L, Rasi G · Annals of the New York Academy of Sciences · DOI 10.1196/annals.1415.044
This review discusses thymosin alpha 1 combinations in animal cancer models and human studies of cancer and chronic hepatitis. It reports effectiveness in animal cancer models and early evidence of potential in human cancer trials. It also describes melanoma and hepatitis C trials as ongoing at publication, without reporting their results.
Thymosin alpha(1) application augments immune response and down-regulates tumor weight and organ colonization in BALB/c-mice.
Beuth J, Schierholz JM, Mayer G · Cancer letters · DOI 10.1016/s0304-3835(00)00510-3
This animal study examined thymosin alpha 1’s immune and antitumor effects in mice implanted with cancer cells. Treatment increased thymus immune cells and circulating blood cells. It also significantly reduced experimentally induced liver and lung metastases and local tumor growth.
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Profile last reviewed September 26, 2026. Educational content only. Not medical advice, a dosing protocol or a treatment recommendation.