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Tα1-RGDR

Tα1-RGDR · Thymosin Alpha-1 RGDR

C
Animal replicated
Research chemicalThymosin Alpha-1 FusionTumor-Targeting PeptideIntegrin-Binding Peptide
RouteInjectableGray-market only
C
Evidence grade: Animal replicated

Effect demonstrated in multiple animal studies; human data sparse or extrapolated. Grades summarize evidence quality, not whether a compound is appropriate, legal, or risk-free.

At a glance
What it is
Thymosin Alpha-1 + RGDR Tumor-Targeting Fusion — Full TA1 + Integrin-Binding Tetrapeptide — Cancer Research Context — Thymosin Alpha-1 Fusion, Tumor-Targeting Peptide, Integrin-Binding Peptide.
Why people use it
Used primarily for immune support.
If you only read one thing

the Full 28-Amino-Acid Thymosin Alpha-1 with an RGDR Tumor-Targeting Sequence Appended. The RGDR Motif Binds Integrin αvβ3 Overexpressed on Tumor Vasculature. A Chinese Pharmaceutical University Research Construct Designed to Concentrate TA1’s Immune Activation at Tumor Sites. What the Lao 2013 and Peng 2020 Papers Actually Show. The Community Use Question: Why a Cancer-Targeting Construct Is in General Use. What Companion Chapter pbta1v4 Covers vs What This Chapter Covers.

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Published literature
0human trials0human studies2animal2in vitro

No Phase 1/2/3 or human pharmacokinetic data exist for the Tα1-RGDR fusion itself; human TA1/Zadaxin evidence is adjacent context, not direct evidence for this tumor-targeting construct.

Evidence reality check
Human evidence
No human studies
0 observational; RCT evidence not present in corpus.
Preclinical base
4 lab signals
2 animal; 2 in-vitro/mechanistic.
Risk posture
No major flags listed
Review route-specific cautions before use.
Categories
Immune & Thymic
Properties
Injectable: extrapolated
Evidence
CAnimal replicated
CRITICAL: What Tα1-RGDR Is
Tα1-RGDR is NOT a fragment of Thymosin Alpha-1. It is the FULL 28-amino-acid Thymosin Alpha-1 (Zadaxin sequence) with an RGDR tetrapeptide appended to the C-terminus via a GGGG flexible linker. Full sequence: Ac-Ser-Asp-Ala-Ala-Val-Asp-Thr-Ser-Ser-Glu-Ile-Thr-Thr-Lys-Asp-Leu-Lys-Glu-Lys-Lys-Glu-Val-Val-Glu-Glu-Ala-Glu-Asn-Gly-Gly-Gly-Gly-Arg-Gly-Asp-Arg. The RGDR motif binds integrin αvβ3 (overexpressed on tumor vasculature and many tumor cell surfaces) and NRP-1, directing TA1 to tumor tissue. This is a tumor-targeting fusion construct, not a standalone small peptide.
The Design Logic
Thymosin Alpha-1 (TA1/Zadaxin) is an immune modulator approved in 35+ countries for hepatitis B/C; it upregulates CD4+ and CD8+ T cells, enhances dendritic cell activity, and modulates innate and adaptive immunity. Its limitation for oncology: it distributes systemically without tumor preference. RGDR provides tumor targeting: RGD (Arg-Gly-Asp) is the integrin-binding motif found in extracellular matrix proteins (fibronectin, vitronectin); integrin αvβ3 is overexpressed on tumor vasculature and tumor cells; the terminal Arg in RGDR is recognized by NRP-1 (neuropilin-1), a co-receptor that further enhances tumor penetration. Tα1-RGDR aims to: (1) bind integrins on tumor tissue; (2) penetrate tumor; (3) deliver TA1's immune-activating effects in situ.
Evidence Base
Lao XZ, et al. (2013, PLOS ONE; PMC3747120): mouse models; Tα1-iRGD fusion; H460 human lung cancer + B16F10 mouse melanoma; enhanced tumor penetration vs unmodified TA1; anti-proliferative activity improved. Peng R, et al. (2020, ACS Omega; PMC7226852): mouse models; Tα1-RGDR specifically; H460 + LLC (Lewis lung carcinoma); 'remarkable antitumor effects'; better tumor distribution and targeting than TA1 alone; CD4+ and CD8+ T cell upregulation maintained. Grade C (animal tumor models). Zero human trials for Tα1-RGDR.
What the Community Uses It For
Limitless sells Tα1-RGDR and describes it as having CD4+/CD8+ T cell upregulation and tumor-targeting properties. Community use: general immune support and anti-cancer adjunct contexts. The compound was designed for cancer-targeted immune activation; community users without active cancer are using a cancer-research construct for general immune purposes. This is a meaningful context mismatch that determines how the evidence should be interpreted.
vs Full TA1 (Zadaxin)
Full TA1 (Zadaxin; thymalfasin): widely studied; approved in 35+ countries; large clinical evidence base for HBV, HCV, cancer adjuvant, COVID-19; well-characterized mechanism. Tα1-RGDR: same TA1 immunopharmacology plus tumor-targeting RGDR addition; only mouse tumor model evidence; no human trials; higher complexity fusion peptide. For immune support without active cancer: unmodified TA1 (Zadaxin) is the better-evidenced option with an established clinical record. Tα1-RGDR is specifically relevant when tumor tissue targeting is the goal.
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