Minigastrin
Also known as: CCK2R targeting peptide, CP04, DOTA-MG11, DOTA-MGS5, Gastrin analogue, MG, Minigastrin, PP-F11N
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Summary
Minigastrin is a short, 13‑amino‑acid fragment of the hormone gastrin that has been chemically linked to a chelator (usually DOTA) and labeled with radionuclides such as 111In, 68Ga or 99mTc. In research settings it is used as a molecular imaging probe to locate tumours that over‑express the cholecystokinin‑2 (CCK‑2, also called CCK‑B) receptor, including medullary thyroid carcinoma, small‑cell lung cancer, astrocytoma and certain gastrointestinal tumours.
Mechanism of Action
The C‑terminal pentapeptide GWMDF‑NH2 of minigastrin binds with high affinity to the G‑protein‑coupled CCK‑2 receptor on the surface of tumour cells. Binding triggers receptor‑mediated internalisation of the peptide‑chelator‑radionuclide complex, concentrating the radioactive signal within the tumour and allowing detection by SPECT or PET imaging. The DOTA chelator securely holds the radionuclide, preserving the peptide’s receptor affinity while delivering a detectable radioactive decay.
What the Research Shows
Multiple preclinical studies have evaluated radiolabelled minigastrin analogues. 111In‑DOTA‑MG0 and variants with histidine tags (111In‑DOTA‑H6‑Met, 111In‑DOTA‑H2‑Met) showed high specific internalisation in CCK‑2‑positive AR42J rat pancreatic tumour cells and tumour uptake in nude‑mouse xenografts. 68Ga‑DOTA‑MG0 has been investigated for PET imaging of CCK‑2‑expressing tumours in mice, while 99mTc‑labelled minigastrin conjugates demonstrated rapid, receptor‑specific tumour localisation. A 2022 review highlighted minigastrin’s potential to improve imaging of medullary thyroid carcinoma and foregut neuroendocrine neoplasms, but human data remain absent.
Reported Benefits
Radiolabelled minigastrin provides receptor‑specific imaging, allowing non‑invasive localisation of CCK‑2‑positive tumours that are otherwise difficult to visualise. Preclinical models report high tumour uptake and favourable tumour‑to‑kidney ratios for certain analogues, supporting its use as a diagnostic tool and a possible theranostic platform when paired with therapeutic radionuclides.
Limitations of the Evidence
Evidence is limited to animal studies and in‑vitro assays; no clinical trials are cited, so human efficacy and safety are unproven. Pharmacokinetic variability, especially renal accumulation, may affect image quality and dosimetry. The need for radiochemical synthesis and short‑lived isotopes also restricts widespread application until further optimisation and regulatory evaluation.
Safety Considerations
Safety data are confined to preclinical reports. Radiolabelled minigastrin delivers ionising radiation, so exposure must be justified and kept as low as reasonably achievable. Animal studies indicate specific tumour uptake but also notable kidney retention, which could increase renal radiation dose. Human adverse‑event profiles are unknown, underscoring the need for careful monitoring in future trials.
How It Is Administered
Minigastrin is administered intravenously as a sterile solution of the peptide conjugated to a chelator (typically DOTA) and labelled with a radionuclide such as 111In, 68Ga or 99mTc. The formulation is injected shortly before imaging, allowing the radiotracer to circulate, bind CCK‑2 receptors, and be visualised by SPECT (111In, 99mTc) or PET (68Ga).
Routes of Administration
Goals & Uses
- Tumor imagingDiagnosticModerate
- Tumor imaging / nuclear medicine diagnosticsDiagnostic ImagingModerate
- Targeted radionuclide therapy of medullary thyroid carcinomaOncology / PRRTModerate
- Small cell lung cancer targetingOncologyLow
- Therapy of gastroenteropancreatic neuroendocrine tumorsOncology / PRRTLow
- Targeted radionuclide therapyTherapeuticLow
Contraindications
- Bone marrow insufficiencyHematologicalModerate
- Severe renal impairmentOrganHighKidney function concerns
- PregnancyPopulationHighPotential fetal risk or insufficient safety data
- BreastfeedingPopulationHighPotential transfer into breast milk or insufficient safety data
- severe gastrointestinal obstructionGastrointestinalModerate
Adverse Effects
- Injection site reactionsLocalUncommon
- Radiation-induced secondary malignancyOncologicRare
- Nausea and vomitingGastrointestinalCommon
- NauseaGastrointestinalCommonFeeling of sickness or urge to vomit
- VomitingGastrointestinalUncommonForceful expulsion of stomach contents
- MyelosuppressionHematologicUncommon
- NephrotoxicityRenalUncommon
- Transient hypotensionCardiovascularRare
Drug Interactions
- Proton pump inhibitors / H2-receptor antagonistsLow
- Other CCK2 agonistsModerate
- Nephrotoxic agents (e.g., aminoglycosides, cisplatin, NSAIDs)High
Population Constraints
- Patients with single kidney or prior renal irradiationOrgan FunctionRelative
- Pediatric patientsAgeRelative
- Patients with prior extensive myelosuppressive therapyHematologicalRelative
Regulatory Status
- European UnionInvestigationalClinical trials ongoing for imaging of CCK2‑positive tumors
- United StatesInvestigationalInvestigational radiopharmaceuticals (e.g., 68Ga‑DOTA‑MG) under IND
- United KingdomInvestigationalNo MHRA approval; investigational use only in research settings.
No regulatory approval in any jurisdiction. Investigated in early-phase clinical trials for diagnostic and therapeutic nuclear medicine applications. Various radiolabeled minigastrin analogues have entered Phase I/II trials in Europe.
Evidence & Sources
- Journal ArticleModerateLeung K2004-01-01T00:00:00.000000Z
- Journal ArticleModerateCheng KT2004-01-01T00:00:00.000000Z
- Journal ArticleModerateLeung K2004-01-01T00:00:00.000000Z
- Journal ArticleModerateChrist E, Wild D, Refardt J2022-01-01T00:00:00.000000Z
- Journal ArticleModerateCheng KT2004-01-01T00:00:00.000000Z
- Journal ArticleModerateThe MICAD Research Team2004-01-01T00:00:00.000000Z
Frequently Asked Questions
What type of tumours can be visualised with minigastrin imaging?
Preclinical work shows high uptake in tumours that over‑express the CCK‑2 receptor, including medullary thyroid carcinoma, small‑cell lung cancer, astrocytoma, stromal ovarian cancer and certain colorectal and pancreatic cancers.
Is minigastrin approved for clinical use?
No. Minigastrin is currently an investigational agent used only in research; no human clinical trials or regulatory approvals are reported in the cited literature.
Why are different radionuclides used with minigastrin?
Different isotopes suit different imaging modalities: 111In and 99mTc emit gamma rays for SPECT, while 68Ga emits positrons for PET. Choice also depends on half‑life, availability and the desired resolution of the scan.
What are the main safety concerns?
The primary concern is radiation exposure, particularly to the kidneys where the peptide can accumulate. Human safety data are lacking, so any clinical use would require careful dosimetry and monitoring.
How is the peptide linked to the radionuclide?
The peptide is chemically attached to the chelator DOTA, which tightly binds the radionuclide (e.g., 111In, 68Ga, 99mTc), preserving the peptide’s ability to bind CCK‑2 receptors while delivering the radioactive signal.
What is Minigastrin?
Minigastrin is a short, 13‑amino‑acid fragment of the hormone gastrin that has been chemically linked to a chelator (usually DOTA) and labeled with radionuclides such as 111In, 68Ga or 99mTc. In research settings it is used as a molecular imaging probe to locate tumours that over‑express the cholecystokinin‑2 (CCK‑2, also called CCK‑B) receptor, including medullary thyroid carcinoma, small‑cell lung cancer, astrocytoma and certain gastrointestinal tumours.
What is Minigastrin used for?
Minigastrin is educationally associated with: Tumor imaging, Tumor imaging / nuclear medicine diagnostics, Targeted radionuclide therapy of medullary thyroid carcinoma, Small cell lung cancer targeting, Therapy of gastroenteropancreatic neuroendocrine tumors, Targeted radionuclide therapy. Educational only — not medical advice.
How is Minigastrin administered?
Recorded routes of administration: Intravenous.
What are the potential side effects of Minigastrin?
Reported adverse effects include: Injection site reactions, Radiation-induced secondary malignancy, Nausea and vomiting, Nausea, Vomiting, Myelosuppression, Nephrotoxicity, Transient hypotension. This list is not exhaustive — consult a qualified clinician.
Who should avoid Minigastrin?
Recorded contraindications: Bone marrow insufficiency, Severe renal impairment, Pregnancy, Breastfeeding, severe gastrointestinal obstruction. Consult a qualified clinician before use.