Maraciclatide
A technetium-99m RGD peptide for imaging new blood vessels and inflamed joints on an ordinary gamma camera
Maraciclatide, first known by its code NC100692, is a ring-shaped RGD peptide built to carry technetium-99m to integrins αvβ3 and αvβ5, receptors that growing blood vessels and inflammatory cells display. It has been used to image breast cancer, metastases, prostate-cancer bone lesions and rheumatoid arthritis. A 2024 placebo-controlled phase 1 study found it safe in healthy volunteers. It is not approved anywhere checked.
Used in human trials: 561–747 MBq (mean 694) with up to 75 µg peptide, Single injection, Intravenous (Study: breast cancer, 20 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?
Growing blood vessels and many inflammatory cells carry receptors called integrins, and two of them, αvβ3 and αvβ5, recognise a three-amino-acid motif, arginine-glycine-aspartate, written RGD. Maraciclatide is a small cyclic peptide containing that motif, with a chelating group that holds the radioactive metal technetium-99m and a polyethylene glycol tail. It was developed under the code NC100692 as a way to see angiogenesis, the growth of new vessels, with the gamma cameras that almost every nuclear-medicine department already owns.
Most RGD tracers that reached people are PET agents labelled with fluorine-18 or gallium-68, such as Galacto-RGD and alfatide II. Technetium-99m is imaged instead with planar and SPECT gamma cameras, equipment that the 2025 arthritis study describes as available in any nuclear-medicine department. The 2008 laboratory study measured binding to both αvβ3 and αvβ5 below 1 nM and found the tracer stable in rat blood, with most activity leaving in urine.
The first human work, in the mid-2000s, was in breast cancer. A 2006 proof-of-concept study gave it to 20 patients with suspicious or benign breast findings and saw 19 of 22 cancers; a small 2008 study with a breast-dedicated camera found 9 of 11. A 2010 multicentre phase 2a study in 25 people with lung or breast cancer found it good for lung and brain metastases and poor for liver and bone lesions. A 2017 comparison with technetium-99m sestamibi, the standard tracer for molecular breast imaging, found the two about equal.
Later studies moved toward inflammation. In rheumatoid arthritis, inflamed joint lining grows new vessels, and a 2025 study of 50 patients found whole-body maraciclatide uptake tracked power Doppler ultrasound closely, joint by joint. Its authors argue that one scan could survey every joint in a way ultrasound cannot. A 2023 paper trained software to outline inflamed tissue on these scans automatically.
In prostate cancer that has spread to bone, a 2018 study of 17 men found the tracer gathered in metastases, more in less dense lesions, and that its uptake moved in different directions after 12 weeks of abiraterone in men whose disease progressed and men whose disease did not. A small 2014 substudy also detected uptake in the hearts of patients with old heart attacks.
The safety record comes from these studies and from a randomised, placebo-controlled phase 1 study in healthy volunteers published in 2024, which found no serious adverse events, a radiation dose similar to other technetium-99m agents and a terminal half-life for the unlabelled peptide of about an hour. ClinicalTrials.gov lists two terminated phase 2 studies and an endometriosis study. Maraciclatide is not approved by the FDA or the EMA.
Mechanism of Action
Maraciclatide carries technetium-99m to αvβ3 and αvβ5 integrins, receptors on endothelial cells in growing vessels and on macrophages, so a gamma camera shows where vessels are forming or tissue is inflamed.
Integrins αvβ3 and αvβ5
The cyclic RGD ring binds both receptors with sub-nanomolar affinity and does not saturate other integrins tested.
New blood vessels
Uptake followed angiogenesis in ischaemic mouse limbs and in tumours, and was blocked by excess peptide or cilengitide.
Inflammation
Macrophages carry αv integrins, so inflamed joints, vessel walls and plaques take it up.
Kidney clearance
Most activity leaves in urine within hours; in people the peptide appears in urine intact.
Published Research
Studies naming maraciclatide or its code NC100692, read from their PubMed abstracts on October 29, 2026. Human imaging studies come first, then the laboratory and animal work that characterised the tracer. Each card reports what its abstract states; diagnostic figures come from small, mostly single-centre studies.
Phase 1 safety and dosimetry
In a randomised, placebo-controlled phase 1 study, healthy volunteers received one of three escalating peptide amounts (eight per group, two on placebo). There were no serious adverse events. Early uptake was highest in the gut (20%), liver (15%) and lungs (9%); about 55% of the technetium-99m left in urine. The effective dose was 7.8 µSv per MBq, and the peptide's terminal half-life was about one hour regardless of amount.
Rheumatoid arthritis: against power Doppler
Fifty people with active rheumatoid arthritis had a 40-joint ultrasound and a whole-body maraciclatide scan the same day. Total scores correlated strongly (r² 0.82 binary, 0.72 quantitative). For small joints with a Doppler signal, the scan had 78% sensitivity, 94% specificity and a 96% negative predictive value.
Software outlines inflamed joints
From 192 hand and wrist scans of 48 patients with rheumatoid arthritis, a neural-network model (nnU-Net) separated normal, mildly and highly inflamed tissue better than a threshold method when checked against clinicians' outlines, an early step toward automated reading of this tracer.
Prostate cancer bone metastases
Seventeen men with bone-predominant metastatic prostate cancer were scanned before abiraterone and 11 again at 12 weeks. Metastases took up the tracer, more in less sclerotic lesions, which the authors link to osteoclast activity. Uptake ratios rose in men whose disease progressed and fell in those whose disease did not.
Breast imaging against sestamibi
Women with suspicious breast lesions had molecular breast imaging with both tracers, read blind. Among 39 analysable patients, maraciclatide showed 19 of 21 cancers and sestamibi 18 of 21; lesion contrast and the area under the ROC curve (0.87 against 0.83) did not differ significantly. Neither tracer's uptake followed tumour subtype.
Heart failure after stem-cell therapy
In a substudy of a bone-marrow stem-cell trial, nine patients with ischaemic heart failure had SPECT with technetium-labelled NC100692 before and four days after intracoronary injection. Uptake was visible in all nine at baseline, suggesting ongoing angiogenesis after old infarcts; changes after treatment were not statistically significant. The scans were well tolerated.
Phase 2a: metastases in lung and breast cancer
Twenty-five patients at ten centres received up to 1,100 MBq. Scans found most lung metastases (21 of 23) and brain metastases (8 of 10) but few liver (1 of 9) or bone (10 of 19) lesions. Safety measures, including ECGs and blood tests over 2.5 hours, stayed stable.
Excreted intact in human urine
Urine from a phase 1 study, after 150 µg of the technetium complex, contained only intact NC100692 and no metabolites, unlike rat urine. About 30% of the injected peptide was excreted within 4 to 8 hours, most of it in the first hour.
Breast-dedicated gamma camera
Eight patients with a high suspicion of breast cancer received 600 to 750 MBq and were imaged with a solid-state breast camera. It showed 9 of 11 cancers, 6 to 20 mm across; the two missed lesions were in multicentric disease, one only 2.5 mm.
First breast-cancer study
Twenty patients (16 with suggestive mammograms, 4 with benign lesions) received up to 75 µg of peptide carrying an average 694 MBq. Scans detected 19 of 22 malignant lesions. Five had mild adverse events; one, a brief altered taste, was judged possibly related to the tracer. There were no serious events.
Measuring it in human plasma
A liquid chromatography-mass spectrometry method quantified NC100692 in human plasma down to 0.5 ng/mL, and showed the peptide stayed stable through freezing and storage, the assay later used for human pharmacokinetics.
Binding and rat biodistribution
The technetium complex bound αvβ3 and αvβ5 with dissociation constants below 1 nM but did not saturate other integrins. In rats it cleared quickly, mostly in urine, with little retention outside liver and kidneys, and showed little breakdown in circulation.
Metabolism in rats
Carbon-14-labelled NC100692 stayed intact in rat blood, but rat urine held two metabolites and no parent peptide; the main one came from cleavage at the C-terminal end.
Angiogenesis after limb ischaemia
In mice whose femoral artery was tied off, the tracer gathered below the blockage at days 3 and 7, matching the new-vessel growth seen on staining; a fluorescent version located on endothelial cells.
Specific uptake in glioma models
In mice with U87 gliomas, uptake was blocked and displaced by cilengitide and by excess unlabelled peptide, and was higher than a non-binding control molecule, evidence that tumour signal reflects the integrin.
Inflamed atherosclerotic plaques
ApoE-deficient mice on a Western diet took up about twice as much tracer in the aortic arch as control mice, and a blocking peptide removed the excess, pointing to integrin-bearing cells in plaques.
Vessel-wall inflammation
In mouse carotid arteries injured with calcium chloride, uptake was higher in the injured vessel and tracked macrophage markers; a fluorescent version bound human monocytes and macrophages.
Dosing Data
Maraciclatide has no approved label. These are the amounts given in published human imaging studies, each a single intravenous injection before scanning.
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 Maraciclatide 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: Maraciclatide 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: “Maraciclatide is dosed by radioactivity and prepared in a hospital radiopharmacy shortly before the scan.”
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 Maraciclatide 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: breast cancer, 20 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: a half-life of about 1 hour (unlabelled peptide, healthy volunteers). After about five half-lives almost none is left.
How long the doses were given: Study: breast cancer, 20 patients: Images 40 minutes to 2.5 hours after injection; Study: metastases in lung and breast cancer (phase 2a, 25 patients): Whole body at 45 minutes, SPECT at 75 minutes; Study: breast-dedicated camera, 8 patients: One imaging session.
When effects appear: unknown; no source on this page gives a time to effect for Maraciclatide. Results reported in the studies are under Published Research.
Source: half-life: PMID 38312052; 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: No serious adverse events in the 2024 placebo-controlled phase 1 study (PMID 38312052); Mild events in 5 of 20 patients in the 2006 study; one brief altered taste possibly related (PMID 16954550); Safety measures, including ECG and blood tests, stable in the phase 2a study (PMID 20001475); Radiation: effective dose about 7.8 µSv per MBq, similar to other technetium-99m agents (PMID 38312052). Full list and cautions ↓
When to stop or get help: unknown; no label or trial on file sets rules for stopping Maraciclatide. Treat a severe or unexpected reaction as a reason to stop and see a doctor.
Source: the Side Effects section below (“From the human studies above”).
Interactions
Unknown: a PubMed search for human interaction studies of Maraciclatide (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 Maraciclatide 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, 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 human studies above.
Contraindications & Cautions
No approved label exists, so there are no official contraindications. Points from the studies:
Legal Status
Maraciclatide is investigational in every jurisdiction checked.
Frequently Asked Questions
?What is maraciclatide?
A small ring-shaped RGD peptide, code NC100692, that carries technetium-99m to integrins αvβ3 and αvβ5 so a gamma camera can show new blood vessels or inflamed tissue.
?How is it different from PET RGD tracers?
Galacto-RGD and alfatide II carry positron emitters for PET. Maraciclatide uses technetium-99m, which works on the gamma cameras most hospitals have, at the cost of less sharp images.
?What has it been used to image?
Breast cancer, lung and brain metastases, prostate-cancer bone metastases, heart tissue after infarction and joint inflammation in rheumatoid arthritis, all in research studies.
?How well does it work in rheumatoid arthritis?
In 50 patients its whole-body joint scores correlated strongly with power Doppler ultrasound, with 94% specificity for small joints (2025 study).
?Is it safe?
No serious adverse events were reported in the studies read, including a 2024 placebo-controlled phase 1 study. It does carry the radiation dose of a nuclear-medicine scan.
?Is it approved?
No. Neither the FDA nor the EMA has a record of it; it remains a research tracer.
References
- [other] PubChem CID 73050806 (synonyms maraciclatide, NC100692): formula C72H120N20O21S3, molecular weight 1698.0. Read October 28, 2026. https://pubchem.ncbi.nlm.nih.gov/compound/73050806
- [registry] ClinicalTrials.gov API v2, read October 28, 2026: NCT01440517 and NCT01230918 (phase 2, terminated); NCT05623332 (endometriosis imaging).
- [clinical-trial] Gibbons T, et al. "Safety, biodistribution and radiation dosimetry of the Arg-Gly-Asp peptide 99m Tc-maraciclatide in healthy volunteers." Nucl Med Commun, 2024;45(4):295-303. PMID: 38312052.
- [pubmed] Attipoe L, et al. "Imaging Neoangiogenesis in Rheumatoid Arthritis (INIRA) Part II: Whole-body Synovial Uptake of (99 m)Tc-maraciclatide is Highly Correlated with Power Doppler Ultrasound." Acad Radiol, 2025;32(10):6027-6036. PMID: 40764199.
- [pubmed] Cobb R, et al. "Deep Learned Segmentations of Inflammation for Novel ⁹⁹(m)Tc-maraciclatide Imaging of Rheumatoid Arthritis." Diagnostics (Basel), 2023;13(21). PMID: 37958194.
- [pubmed] Cook GJR, et al. "Imaging α(v)β(3) integrin expression in skeletal metastases with (99m)Tc-maraciclatide single-photon emission computed tomography: detection and therapy response assessment." Eur J Nucl Med Mol Imaging, 2018;45(6):898-903. PMID: 29396636.
- [pubmed] O'Connor MK, et al. "Comparison of Tc-99m maraciclatide and Tc-99m sestamibi molecular breast imaging in patients with suspected breast cancer." EJNMMI Res, 2017;7(1):5. PMID: 28091980.
- [clinical-trial] Mozid AM, et al. "Clinical feasibility study to detect angiogenesis following bone marrow stem cell transplantation in chronic ischaemic heart failure." Nucl Med Commun, 2014;35(8):839-48. PMID: 24769888.
- [clinical-trial] Axelsson R, et al. "An open-label, multicenter, phase 2a study to assess the feasibility of imaging metastases in late-stage cancer patients with the alpha v beta 3-selective angiogenesis imaging agent 99mTc-NC100692." Acta Radiol, 2010;51(1):40-6. PMID: 20001475.
- [pubmed] Roed L, et al. "Human urinary excretion of NC100692, an RGD-peptide for imaging angiogenesis." Eur J Pharm Sci, 2009;37(3-4):279-83. PMID: 19491016.
- [pubmed] Bach-Gansmo T, et al. "Integrin scintimammography using a dedicated breast imaging, solid-state gamma-camera and (99m)Tc-labelled NC100692." Clin Physiol Funct Imaging, 2008;28(4):235-9. PMID: 18384623.
- [pubmed] Bach-Gansmo T, et al. "Integrin receptor imaging of breast cancer: a proof-of-concept study to evaluate 99mTc-NC100692." J Nucl Med, 2006;47(9):1434-9. PMID: 16954550.
- [pubmed] Oulie I, et al. "Quantification of NC100692, a new tracer for 99mTc-imaging of angiogenesis, in human plasma using reversed-phase liquid chromatography coupled with electrospray ionization ion-trap mass spectrometry." J Chromatogr B Analyt Technol Biomed Life Sci, 2007;852(1-2):605-10. PMID: 17353156.
- [pubmed] Edwards D, et al. "99mTc-NC100692--a tracer for imaging vitronectin receptors associated with angiogenesis: a preclinical investigation." Nucl Med Biol, 2008;35(3):365-75. PMID: 18355693.
- [pubmed] Roed L, et al. "Metabolism in rats of NC100692, an RGD-peptide for imaging of angiogenesis." J Pharm Biomed Anal, 2008;47(1):164-9. PMID: 18242918.
- [pubmed] Hua J, et al. "Noninvasive imaging of angiogenesis with a 99mTc-labeled peptide targeted at alphavbeta3 integrin after murine hindlimb ischemia." Circulation, 2005;111(24):3255-60. PMID: 15956134.
- [pubmed] Dearling JL, et al. "Specific uptake of 99mTc-NC100692, an αvβ3-targeted imaging probe, in subcutaneous and orthotopic tumors." Nucl Med Biol, 2013;40(6):788-94. PMID: 23701702.
- [pubmed] Vancraeynest D, et al. "αVβ3 integrin-targeted microSPECT/CT imaging of inflamed atherosclerotic plaques in mice." EJNMMI Res, 2016;6(1):29. PMID: 27009066.
- [pubmed] Razavian M, et al. "Integrin-targeted imaging of inflammation in vascular remodeling." Arterioscler Thromb Vasc Biol, 2011;31(12):2820-6. PMID: 21940943.
Sources & Citations
Studies were read from their PubMed abstracts on October 29, 2026; trial registrations and status from ClinicalTrials.gov, Drugs@FDA and the EMA medicines list, read October 28, 2026. 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.