VMT-α-NET
The somatostatin-receptor peptide built to carry a matched pair of lead isotopes, one to image neuroendocrine tumours and one to treat them with alpha particles, and what the first patients showed
VMT-α-NET (chemically PSC-PEG2-TOC) is a modified octreotide, the somatostatin-like peptide that homes in on somatostatin receptor 2 on neuroendocrine tumour cells, fitted with a chelator designed for lead. With lead-203 it is an imaging agent for SPECT scans; with lead-212 it delivers alpha radiation to the tumour. Because both are lead, the scan predicts where the therapy will go. Mouse studies picked it from a series of designs, and since 2022 small clinical reports and a phase 0 imaging trial have described its first use in people. It is investigational and given only in nuclear medicine departments.
Used in human trials: 4.9 MBq/kg, Single injection, Intravenous (Lead-203 imaging, first clinical series (12 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?
Most neuroendocrine tumours, the slow-growing cancers that arise from hormone-making cells of the gut and pancreas, carry large numbers of somatostatin receptors, especially subtype 2 (SSTR2). Octreotide and similar peptides bind that receptor, and with a radioactive metal attached they can either map the tumours on a scan or irradiate them from inside. Lutetium-177 DOTATATE, a beta-emitting version, is an approved treatment. Alpha emitters deposit far more energy over a much shorter distance, so researchers have looked to them for tumours that stop responding to beta therapy.
Lead-212 is attractive for that job. Its half-life of about 10.6 hours suits small peptides, and as it decays it produces alpha-emitting daughters inside the tumour. Lead-203 is chemically identical but gives off gamma rays, so a scan with the lead-203 version shows where the lead-212 version will go and lets doctors estimate radiation doses before treating. The difficulty is that standard chelators such as DOTA were designed for other metals and do not hold lead as well.
VMT-α-NET came out of a design study that changed three things in Tyr3-octreotide-based compounds: the way the peptide ring was closed, a chelator made for lead, and a short polyethylene glycol spacer. In tumour-bearing mice the selected compound, PSC-PEG2-TOC, bound the receptor and stayed in tumours better than the lead-203 version of DOTATOC and cleared faster through the kidneys; three fractions of lead-212 therapy left 80% of mice alive at 120 days, 70% with complete response. A later side-by-side mouse comparison of lead-212 compounds found DOTAMTATE, a rival lead-chelating octreotate, had the more favourable tumour-to-kidney balance, and found the lead-specific chelator slower to label.
The first human reports were single patients. In 2022 a man with end-stage midgut tumour that had stopped responding to six cycles of lutetium-177 therapy was scanned with lead-203 VMT-α-NET, and his liver metastases took it up as they did on gallium-68 PET. An Indian case in 2024 showed the same match, and another described the first post-treatment imaging and dosimetry of lead-212 VMT-α-NET in a 41-year-old woman, who had a partial response.
The first series came from Germany in 2025: 12 heavily pretreated patients, including some already given lutetium-177 and actinium-225 DOTATATE, were imaged with lead-203 VMT-α-NET and, where eligible, given one dose of the lead-212 form. No high-grade or serious side effects occurred, and scans and tumour markers were stable three months later. A US phase 0 imaging trial in 10 patients published in 2026 found that lead-203 SPECT detected 97 of 162 lesions seen on standard PET, picking up 94% of those over 1 cm but only 35% of smaller ones, and estimated the kidney as the organ receiving the most radiation among normal tissues.
So far the human evidence is a dozen treated patients with short follow-up, a handful of case reports and one imaging trial. Phase 1/2 and early phase 1 trials are registered. VMT-α-NET is not approved anywhere; it is produced in licensed radiopharmacies, including by an automated method published in 2024, and given intravenously by nuclear medicine staff. It is not something anyone can buy or use outside that setting.
Mechanism of Action
VMT-α-NET binds somatostatin receptor 2 on neuroendocrine tumour cells. Its lead-specific chelator carries either lead-203, whose gamma rays are imaged, or lead-212, whose decay chain releases alpha particles of high energy and very short range inside the tumour.
SSTR2 targeting
The Tyr3-octreotide part binds somatostatin receptor 2, highly expressed on most neuroendocrine tumours; cell uptake in receptor-positive cells rose with molar activity in a 2023 study.
A chelator built for lead
The lead-specific chelator and PEG2 spacer improved receptor binding, tumour accumulation and kidney clearance over lead-labelled DOTATOC in mice.
Matched imaging and therapy
Lead-203 and lead-212 are the same element, so a lead-203 scan shows where lead-212 will go and allows dosimetry before treatment.
Alpha particles from lead-212
Lead-212 decays to bismuth-212, and the chain that follows includes a single alpha decay, which delivers high energy over a very short range in the tissue where the drug has gathered.
Published Research
These studies of VMT-α-NET (PSC-PEG2-TOC) were read from their PubMed abstracts on October 30, 2026: the first patient reports and clinical series, the phase 0 imaging trial, the mouse design and comparison studies, and the radiochemistry. Some name the compound by its chemical name, and two name it only in the abstract; each was read and recorded as a study of this molecule.
Phase 0 imaging and dosimetry trial in 10 patients
Patients with SSTR2-positive tumours had SPECT/CT up to 48 hours after about 185 MBq of lead-203 VMT-α-NET. Of 162 lesions on standard PET, 97 were seen, with best contrast at 4 hours; sensitivity was 94% for lesions over 1 cm and 35% for smaller ones. The effective dose was 0.038 mSv per MBq, and the kidneys had the highest estimated dose of the normal organs.
First clinical series: 12 heavily pretreated patients
Patients with progressive metastatic gastroenteropancreatic tumours, grade 1 to 3, had lead-203 imaging and, where eligible, one dose of lead-212 VMT-α-NET after exhausting other therapies including lutetium-177 and actinium-225 DOTATATE. Uptake was high but varied between lesions, comparable to gallium-68 DOTATATE PET. No high-grade or serious adverse effects occurred, and findings were stable at three months.
First imaging-based dosimetry after lead-212 therapy
A 41-year-old woman with advanced grade 2 neuroendocrine tumour was given one cycle of lead-212 VMT-α-NET and imaged afterwards to estimate absorbed doses directly, rather than extrapolating from lead-203. She had a partial response.
Lead-203 scan matching gallium-68 DOTANOC
In a patient with metastatic neuroendocrine tumour, lead-203 VMT-α-NET was distributed in the same places as a gallium-68 DOTANOC PET scan, supporting its use to check suitability for lead-212 therapy.
First published scan in a patient
A man with end-stage midgut tumour, carcinoid heart disease and reduced kidney function, no longer responding after six cycles of lutetium-177 therapy, was scanned at 1.5 and 22 hours after 224 MBq of lead-203 VMT-α-NET. His liver metastases showed high uptake matching gallium-68 PET, to judge whether lead-212 therapy was feasible.
Review of alpha-emitter receptor therapy
Pooling seven studies with 150 patients, the review found most data for actinium-225 DOTATATE (response in half, disease control in 81%). Lead-212 VMT-α-NET and bismuth-213 DOTATOC studies showed promising disease control with few grade 3 or higher blood or kidney toxicities, and phase 3 trials are needed.
The design study that chose it
New octreotide peptides with a modified ring closure, a lead-specific chelator and PEG linkers were tested in tumour cells and mice. PSC-PEG2-TOC beat lead-203 DOTATOC on receptor binding, tumour accumulation and retention, cleared faster through the kidneys, and as lead-212 therapy gave dose-dependent effects; three fractions left 80% of mice alive at 120 days.
Side by side with other lead-212 somatostatin compounds
In tumour-bearing mice, DOTAM and DOTA chelators labelled lead more efficiently and faster than the lead-specific chelator of PSC-PEG2-TOC, and lead-212 DOTAMTATE had the best tumour-to-kidney exposure ratio of the compounds compared.
Molar activity and cell uptake
Lead-203 and lead-212 PSC-PEG2-TOC were labelled at more than 95% purity and yield. Uptake was highest in a pancreatic SSTR2-positive cell line (17.9%), lower in receptor-transfected cells and minimal in receptor-poor cells, and rose with molar activity; 15 to 40 MBq/nmol worked best.
Automated GMP production of the lead-212 form
Adapting a commercial synthesis module, the whole process from generator elution to sterile filtration ran automatically within an hour, giving lead-212 VMT-α-NET at more than 95% purity and yield over ten runs, ready for patient use.
Dosing Data
VMT-α-NET has no approved label anywhere. The rows below are administered activities, the amount of radioactivity injected into a vein, as given in the human studies carded above. They are measured in megabecquerels (MBq), sometimes per kilogram of body weight, not in milligrams.
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 VMT-α-NET 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: VMT-α-NET 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: “VMT-α-NET is dosed by radioactivity and labelled with lead-203 or lead-212 in a radiopharmacy shortly before use; no reconstitution maths applies.”
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 VMT-α-NET 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; Lead-203 imaging, first clinical series (12 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: Lead-203 imaging, first clinical series (12 patients): Imaging up to 24 hours; Lead-212 therapy, first clinical series (eligible patients): One cycle, follow-up to 3 months; Lead-203 imaging, phase 0 dosimetry trial (10 patients): SPECT/CT up to 48 hours.
When effects appear: unknown; no source on this page gives a time to effect for VMT-α-NET. 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: No high-grade or serious adverse effects after lead-203 imaging or one lead-212 therapy dose in 12 patients (PMID 40202686); Few grade 3 or higher blood or kidney toxicities across early alpha-emitter studies including lead-212 VMT-α-NET (PMID 41304857); The kidneys receive the highest radiation dose among normal organs per MBq, and the spleen and liver smaller doses (PMID 41644295). Full list and cautions ↓
When to stop or get help: unknown; no label or trial on file sets rules for stopping VMT-α-NET. 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, which are small and short”).
Interactions
Unknown: a PubMed search for human interaction studies of VMT-α-NET (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 VMT-α-NET 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 studies above, which are small and short.
Contraindications & Cautions
There is no approved label, so there are no official contraindications. Points from the studies above:
Legal Status
VMT-α-NET is not approved by any regulator checked. It is made and given in hospitals under trial or compassionate-use rules.
Frequently Asked Questions
?What is VMT-α-NET?
A modified octreotide peptide (PSC-PEG2-TOC) that binds somatostatin receptor 2 on neuroendocrine tumours and carries radioactive lead: lead-203 for imaging or lead-212 for alpha-particle therapy.
?Why lead?
Lead-212 releases alpha particles through its decay chain and has a half-life that suits small peptides, and lead-203 is the same element, so a scan with it predicts where the therapy will go.
?How does it compare with lutetium-177 DOTATATE?
Lutetium-177 DOTATATE is approved and gives beta radiation. VMT-α-NET is experimental and gives alpha radiation; in the first series it was used in patients whose tumours had progressed after lutetium-177 and even actinium-225 therapy.
?Does it work?
Too few patients have been treated to say. The first 12 tolerated it without serious side effects and were stable three months later, and one case had a partial response; larger trials are under way.
?Is it approved?
No. Drugs@FDA and the EMA list hold no record; trials are registered on ClinicalTrials.gov.
?Can anyone buy it?
No. It is a short-lived radioactive drug prepared in licensed radiopharmacies and given by nuclear medicine staff.
References
- [registry] ClinicalTrials.gov API v2, read October 28, 2026: NCT05636618 (phase 1/2, targeted alpha-particle therapy for SSTR2-positive tumours, recruiting); NCT06148636 (early phase 1, lead-212 VMT-alpha-NET, active, not recruiting); NCT05111509 (early phase 1, imaging).
- [pubmed] Graves SA, et al. "A Phase 0 Imaging Trial of [(203)Pb]Pb-VMT-α-NET to Enable Dosimetry and Treatment Planning for Refractory or Relapsed Metastatic Neuroendocrine Tumors with [(212)Pb]Pb-VMT-α-NET." J Nucl Med, 2026;67(4):576-583. PMID: 41644295.
- [pubmed] Michler E, et al. "[(203/212)Pb]Pb-VMT-α-NET as a novel theranostic agent for targeted alpha radiotherapy-first clinical experience." Eur J Nucl Med Mol Imaging, 2025;52(11):4171-4183. PMID: 40202686.
- [pubmed] Singh N, et al. "Charting the Course of Targeted α Therapy With First-in-Human, Postadministration Image-Guided Dosimetry and Response Assessment of 212 Pb-VMT-α-NET in Metastatic Neuroendocrine Tumors." Clin Nucl Med, 2024;49(6):546-548. PMID: 38537249.
- [pubmed] Thakral P, et al. "Lead-203 VMT-α-Neuroendocrine Tumor Scintigraphy: A Promising Theranostics Agent." Indian J Nucl Med, 2024;39(2):142-143. PMID: 38989305.
- [pubmed] Müller D, et al. "203 Pb-VMT-α-NET Scintigraphy of a Patient With Neuroendocrine Tumor." Clin Nucl Med, 2023;48(1):54-55. PMID: 36257061.
- [pubmed] Leupe H, et al. "Clinical Experience with Targeted Alpha-Emitter Peptide Receptor Radionuclide Therapy (α-PRRT) for Somatostatin Receptor-Positive Neuroendocrine Tumors." Pharmaceuticals (Basel), 2025;18(11). PMID: 41304857.
- [pubmed] Lee D, et al. "Structural modifications toward improved lead-203/lead-212 peptide-based image-guided alpha-particle radiopharmaceutical therapies for neuroendocrine tumors." Eur J Nucl Med Mol Imaging, 2024;51(4):1147-1162. PMID: 37955792.
- [pubmed] Saidi A, et al. "Side-by-Side Comparison of the In Vivo Performance of [(212)Pb]Pb-DOTAMTATE and Other SSTR2-Targeting Compounds." J Nucl Med, 2025;66(3):391-397. PMID: 39884771.
- [pubmed] Pretze M, et al. "Influence of the Molar Activity of (203/212)Pb-PSC-PEG(2)-TOC on Somatostatin Receptor Type 2-Binding and Cell Uptake." Pharmaceuticals (Basel), 2023;16(11). PMID: 38004470.
- [pubmed] Pretze M, et al. "Lead-it-EAZY! GMP-compliant production of [(212)Pb]Pb-PSC-PEG(2)-TOC." EJNMMI Radiopharm Chem, 2024;9(1):81. PMID: 39604560.
Sources & Citations
Every study on this page was read from its PubMed record on October 30, 2026. Approval status comes from Drugs@FDA (openFDA) and the EMA medicines list, and trial status from the ClinicalTrials.gov API, read October 28, 2026. PubChem held no record under this name. 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.