Galacto-RGD
The first PET tracer for integrin αvβ3 tried in people, and the proof that its uptake matched the receptor
Galacto-RGD is a small ring-shaped RGD peptide with a sugar attached, labelled with fluorine-18 for PET. It binds integrin αvβ3, a receptor on new blood vessels and on many cancer cells. From 2005 researchers used it to show that a PET scan could measure this receptor in patients. It stayed a research tracer, partly because it is slow to make, and is not approved.
Used in human trials: 133–200 MBq, Single injection, Intravenous (Study: radiation dosimetry, 18 patients) Details ↓
Recommended Dosing
Used in human trials
No manufacturer dose exists for this use: these are amounts given in published trials, not recommendations.
What is it?
Integrin αvβ3 is a receptor that lets cells grip the tissue around them. Endothelial cells lining new blood vessels display it, as do many tumour cells, and it helps cancers spread. Drugs aimed at it, such as the RGD peptide cilengitide, were being tested in trials, and doctors wanted a way to see which tumours carried the receptor before treating them. Galacto-RGD was designed for that.
The tracer is the cyclic peptide cyclo(RGDfK), whose arginine-glycine-aspartate motif fits αvβ3, joined to an amino acid made from galactose. Adding sugar groups had improved how RGD peptides behaved in the body, giving good tumour-to-background contrast, and in patients galacto-RGD left mainly through the kidneys. A fluorine-18 label is attached through a small linker. The 2004 synthesis paper reported high radiochemical purity but a total preparation time of over three hours, a point later groups raised when proposing faster gallium-68 alternatives.
Human studies followed quickly. In 19 cancer patients the tracer left the blood fast, went out through the kidneys and showed tumours with good contrast, and modelling suggested specific, reversible binding. In 18 patients the effective radiation dose was 18.7 µSv per MBq, and over 95% of the tracer in blood was intact two hours after injection. Most important, in 19 patients scanned before surgery, uptake matched αvβ3 staining of the removed tissue closely, and two tumours with no uptake had no αvβ3. This was the first proof in people that a PET scan could measure the receptor.
The tracer then went through a series of cancers. It found 10 of 12 head and neck cancers, missing two under 5 mm, with the receptor mostly on vessels. It found every invasive breast cancer in 16 women, with highly variable uptake. In glioblastoma it lit up the actively growing edges while normal brain stayed dark, and surgeons used the fused images to plan biopsies. Against FDG in 18 patients with lung and other cancers, it was less sensitive for staging (76%), and the two tracers' uptake hardly correlated, so the authors saw it as a tool for planning αvβ3-targeted treatment rather than for staging.
Because inflamed tissue also builds new vessels and recruits αvβ3-bearing macrophages, galacto-RGD was tested outside cancer. In mice it picked up chronic, but not acute, skin inflammation, and atherosclerotic plaque, where uptake fell after a cholesterol-lowering diet. A rat study followed the receptor in healing heart muscle after infarction, and a 2014 study in 10 people found higher uptake in narrowed carotid arteries that matched αvβ3 in the removed plaque.
Drugs@FDA and the EMA hold no record of galacto-RGD, and ClinicalTrials.gov lists no study under its name. Its slow synthesis was a practical limit: a 2012 mouse study found that a gallium-68 RGD tracer made in 15 minutes behaved much the same. Other αvβ3 tracers on this site include the fluorine-18 tracers fluciclatide and alfatide II and the technetium-99m SPECT tracer 3PRGD2.
Mechanism of Action
Galacto-RGD binds integrin αvβ3 through its arginine-glycine-aspartate motif and carries fluorine-18, so a PET scan can show and measure the receptor on new vessels and tumour cells.
Integrin αvβ3
The cyclic RGD peptide binds αvβ3; uptake correlated with receptor staining in tissue removed at surgery.
Sugar for clearance
The galactose-based amino acid was added to improve its behaviour in the body; in patients it cleared fast from blood, mainly through the kidneys.
PET imaging
Fluorine-18 lets PET measure uptake; scans were taken about an hour after injection.
Inflammation
Chronic inflammation and plaque macrophages also carry αvβ3, shown in mouse and human carotid studies.
Published Research
Studies whose titles name galacto-RGD, read from their PubMed abstracts on October 29, 2026. Human studies come first, then animal work. The technetium-99m dimer galacto-RGD2 is a different molecule and is not included; two studies titled only for integrin imaging are listed under References.
Uptake matches αvβ3 in people
Nineteen patients with solid tumours were scanned before surgery, and 26 tissue samples were stained for αvβ3. Uptake (standardised uptake values of 1.2 to 10.0 in positive tumours) correlated with staining intensity (r = 0.92) and with the density of αvβ3-positive vessels (r = 0.84); two tumours without uptake, and normal tissue, had no αvβ3.
Biodistribution in 19 patients
Patients with melanoma metastases, sarcomas or bone metastases received 133 to 200 MBq. The tracer cleared fast through the kidneys; tumour uptake values ranged from 1.2 to 9.0 and tumour-to-muscle ratios reached about 7.7 at 72 minutes. Tumour distribution volume was about four times that of muscle, consistent with specific binding.
Radiation dosimetry
In 18 patients given 133 to 200 MBq, over 95% of the tracer in serum was intact at 120 minutes, lung and muscle background was low, the effective dose was 18.7 µSv per MBq and the bladder wall received the most, 0.22 mGy per MBq.
Seeing the receptor, mice and patients
In mouse tumours, uptake matched αvβ3 measured afterwards, and was sensitive enough to show receptor on tumour vessels alone; in patients with malignant tumours the scan showed the pattern of αvβ3 on tumour and vessel cells quantitatively.
Head and neck cancer
In 11 patients with squamous cell carcinoma given 140 to 200 MBq, PET found 10 of 12 tumours (uptake values 2.2 to 5.8) and missed two under 5 mm. Staining showed αvβ3 on the microvessels of every tumour and on tumour cells in one; fusing PET with MRI or CT to outline subvolumes was feasible.
Breast cancer
In 16 women with primary or metastatic invasive ductal cancer, the scan identified every invasive cancer (uptake values 1.4 to 8.7) and node metastases in 3 of 8 patients; uptake varied widely, and αvβ3 was mainly on vessels.
Against FDG in 18 patients
Across 59 lesions, mostly from lung cancer, galacto-RGD detected 76% against clinical staging. FDG uptake was much higher (mean uptake value 7.6 against 2.7), and the two tracers' uptake did not correlate (r = 0.16), so they report different biology.
Glioblastoma
Normal brain took up almost none (uptake value 0.09), while glioblastomas showed patchy uptake (mean 1.6), highest in proliferating, infiltrating areas, matching αvβ3 staining of samples taken from those areas under image guidance.
Synthesis and dose estimates
The sugar amino acid was made from galactose in four steps and the label added through 4-nitrophenyl-2-[18F]fluoropropionate, with over 98% purity but about 200 minutes in total. In mice 69% to 87% of the tracer was intact in tissues at two hours; rabbit data gave an estimated human effective dose of 0.022 mGy per MBq.
Skin inflammation in mice
In a repeated allergic skin reaction in mouse ears, uptake of RGD tracers did not rise in the acute phase but rose steadily as chronic inflammation built new vessels; galacto-RGD PET showed this, and an unlabelled RGD peptide blocked it.
Atherosclerotic mice
In mice with high cholesterol, uptake was higher in the diseased aorta and focal in plaques, associated with macrophage density rather than new vessels, and blocked by competition.
Diet lowers plaque uptake
Atherosclerotic mice switched to normal chow for three months had 35% lower plaque uptake on autoradiography than mice kept on a high-fat diet, although plaque size was similar.
A faster gallium-68 substitute
In melanoma-bearing mice, gallium-68 NODAGA-RGD, made in 15 minutes, gave tumour uptake similar to galacto-RGD (1.45% against 1.35% of the injected dose per gram) with less uptake in the gallbladder and gut.
Dosing Data
Galacto-RGD has no approved label. These are activities given in published human studies, as a single injection of a radioactive tracer before PET.
Educational information, not medical advice. Each dose above is tagged with its source: an approved label, a published human study, animal data, or amounts reported by users. None is a recommendation for you. An unapproved compound has no established safe or effective human dose, and products sold for “research use only” are not made or tested for people. Talk to a doctor before acting on anything on this site, including before you start, stop or change any medicine or dose. Full medical disclaimer.
What a Buyer Needs to Know
What is sold, how it is mixed, stored and taken, and what is known about its safety, quality and legal status. Each part names its source. Where we have none, it says unknown.
What is sold
Unknown: we hold no regulator's label that says in what form Galacto-RGD is supplied. It is a radioactive drug: the next part says where it is prepared and given.
Mixing a vial: a worked example
Nothing to mix at home, and no syringe units to work out: Galacto-RGD is a radioactive drug, prepared and given in nuclear-medicine departments, and its dose is an amount of radioactivity (MBq or GBq), not a weight.
This page's dosing note: “Galacto-RGD is dosed by radioactivity and made with fluorine-18 shortly before the scan, then given in nuclear-medicine departments.”
Source: this page's own note in Dosing Data below; the amount of each dose row in Dosing Data below.
Storage before and after mixing
Unknown: no label on file says how Galacto-RGD is stored. It is a radioactive drug held by the nuclear-medicine department that prepares and gives it (see the part above); the home rules for a mixed vial in the mixing guide do not apply to it.
How it is taken
As it was given in human studies: Intravenous (Single injection; Study: radiation dosimetry, 18 patients).
Source: Used in human trials: the route and frequency of each row in Dosing Data below.
What to expect, and when
How long it stays in the body: not established by a measurement cited on this entry.
How long the doses were given: Study: radiation dosimetry, 18 patients: Scans up to about 70 minutes after injection; Study: head and neck cancer, 11 patients: Static scan at 60 minutes.
When effects appear: unknown; no source on this page gives a time to effect for Galacto-RGD. Results reported in the studies are under Published Research.
Source: Used in human trials, the duration of each row in Dosing Data below.
Side effects, and when to stop or get help
From the Side Effects section: Radiation exposure: an effective dose of 18.7 µSv per MBq, highest in the bladder wall; A single diagnostic injection; no side-effect data are given in the abstracts read. Full list and cautions ↓
When to stop or get help: unknown; no label or trial on file sets rules for stopping Galacto-RGD. Treat a severe or unexpected reaction as a reason to stop and see a doctor.
Source: the Side Effects section below (“From the studies above”).
Interactions
Unknown: a PubMed search for human interaction studies of Galacto-RGD (reviewed 2026-10-28) found none. Unknown is not the same as safe to combine.
Every peptide's record, with its source: the interaction matrix.
Checking what you bought
Unknown: no published independent test of Galacto-RGD products is in our lab-results database yet, so how products sold under this name measure up is not known.
To read a certificate of analysis, paste it into the COA decoder. Trust & Verification explains what independent testing can and cannot show.
Legal status
US: In Clinical Trials (Not approved: Drugs@FDA and the EMA medicines list hold no record (searched October 28 and 29, 2026)). Sport: Prohibited (S0 catch-all).
Country by country ↓ · Regulatory tracker
Source: this entry's approval status and the WADA Prohibited List, as in Legal Status below.
Side Effects & Contraindications
Reported Side Effects
From the studies above. None of the abstracts read reports an adverse reaction to the tracer.
Contraindications & Cautions
No approved label exists, so there are no official contraindications. Points from the studies above:
Legal Status
Galacto-RGD is investigational in every jurisdiction checked.
Frequently Asked Questions
?What is galacto-RGD?
A PET tracer: the cyclic RGD peptide cyclo(RGDfK) with a galactose-based sugar attached, labelled with fluorine-18. It binds integrin αvβ3 on new blood vessels and many tumour cells.
?Why does it matter?
It was the first αvβ3 tracer shown in people to reflect the receptor itself: in 19 patients scanned before surgery, uptake matched receptor staining in the removed tumours closely.
?Is it approved?
No. Drugs@FDA and the EMA hold no record, and it remained a research tracer.
?Is it better than FDG?
Not for finding cancer. In 18 patients it was less sensitive for staging, and its uptake did not correlate with FDG. It measures a different thing, the receptor targeted by some drugs.
?Why the sugar?
Sugar groups improved how RGD peptides behaved in the body. In patients galacto-RGD cleared fast, mainly through the kidneys, and lung and muscle background was low; a gallium-68 RGD tracer compared in mice was more water-loving still and showed less in the gallbladder and gut.
?Why did it not go further?
Making it takes over three hours with several steps; a gallium-68 RGD tracer made in 15 minutes behaved similarly in mice.
References
- [other] PubChem CID 131676682, Galacto-RGD: formula C34H52N10O12, molecular weight 792.8. Read October 28, 2026. https://pubchem.ncbi.nlm.nih.gov/compound/131676682
- [pubmed] Haubner R, et al. "Noninvasive visualization of the activated alphavbeta3 integrin in cancer patients by positron emission tomography and [18F]Galacto-RGD." PLoS Med, 2005;2(3):e70. PMID: 15783258.
- [pubmed] Beer AJ, et al. "Biodistribution and pharmacokinetics of the alphavbeta3-selective tracer 18F-galacto-RGD in cancer patients." J Nucl Med, 2005;46(8):1333-41. PMID: 16085591.
- [pubmed] Beer AJ, et al. "PET-based human dosimetry of 18F-galacto-RGD, a new radiotracer for imaging alpha v beta3 expression." J Nucl Med, 2006;47(5):763-9. PMID: 16644745.
- [pubmed] Beer AJ, et al. "Positron emission tomography using [18F]Galacto-RGD identifies the level of integrin alpha(v)beta3 expression in man." Clin Cancer Res, 2006;12(13):3942-9. PMID: 16818691.
- [pubmed] Beer AJ, et al. "[18F]galacto-RGD positron emission tomography for imaging of alphavbeta3 expression on the neovasculature in patients with squamous cell carcinoma of the head and neck." Clin Cancer Res, 2007;13(22 Pt 1):6610-6. PMID: 18006761.
- [pubmed] Beer AJ, et al. "Comparison of integrin alphaVbeta3 expression and glucose metabolism in primary and metastatic lesions in cancer patients: a PET study using 18F-galacto-RGD and 18F-FDG." J Nucl Med, 2008;49(1):22-9. PMID: 18077538.
- [pubmed] Beer AJ, et al. "Patterns of alphavbeta3 expression in primary and metastatic human breast cancer as shown by 18F-Galacto-RGD PET." J Nucl Med, 2008;49(2):255-9. PMID: 18199623.
- [pubmed] Schnell O, et al. "Imaging of integrin alpha(v)beta(3) expression in patients with malignant glioma by [18F] Galacto-RGD positron emission tomography." Neuro Oncol, 2009;11(6):861-70. PMID: 19401596.
- [pubmed] Haubner R, et al. "[18F]Galacto-RGD: synthesis, radiolabeling, metabolic stability, and radiation dose estimates." Bioconjug Chem, 2004;15(1):61-9. PMID: 14733584.
- [pubmed] Pichler BJ, et al. "Imaging of delayed-type hypersensitivity reaction by PET and 18F-galacto-RGD." J Nucl Med, 2005;46(1):184-9. PMID: 15632051.
- [pubmed] Laitinen I, et al. "Evaluation of alphavbeta3 integrin-targeted positron emission tomography tracer 18F-galacto-RGD for imaging of vascular inflammation in atherosclerotic mice." Circ Cardiovasc Imaging, 2009;2(4):331-8. PMID: 19808614.
- [pubmed] Saraste A, et al. "Diet intervention reduces uptake of αvβ3 integrin-targeted PET tracer 18F-galacto-RGD in mouse atherosclerotic plaques." J Nucl Cardiol, 2012;19(4):775-84. PMID: 22527796.
- [pubmed] Pohle K, et al. "68Ga-NODAGA-RGD is a suitable substitute for (18)F-Galacto-RGD and can be produced with high specific activity in a cGMP/GRP compliant automated process." Nucl Med Biol, 2012;39(6):777-84. PMID: 22444238.
- [pubmed] Beer AJ, et al. "PET/CT imaging of integrin αvβ3 expression in human carotid atherosclerosis." JACC Cardiovasc Imaging, 2014;7(2):178-87. PMID: 24412187.
- [pubmed] Higuchi T, et al. "Assessment of alphavbeta3 integrin expression after myocardial infarction by positron emission tomography." Cardiovasc Res, 2008;78(2):395-403. PMID: 18256073.
Sources & Citations
Studies were read from their PubMed abstracts on October 29, 2026. Formula and weight are PubChem's. Status is from Drugs@FDA, the EMA medicines list and ClinicalTrials.gov. Grey Peptides sells nothing and links to no vendor.
Medical Disclaimer: This content is for educational and informational purposes only. It is not medical advice, and nothing here is an instruction to obtain or use any compound. Talk to a licensed clinician about your own situation.