DosimetryNCT06398392
Radiation Dosimetry of the 18 kDa Translocator Protein Ligand [18F]PBR111 in Humans
A study testing [18F]PBR111, PBR111 injection and PET scan in people with Dosimetry and Healthy, run by Prof. Daniele Zullino at 1 site in Switzerland.
Trial summary
The 18 kDa translocator protein (TSPO) is a mitochondrial protein that becomes overexpressed during neuroinflammatory conditions, such as in Alzheimer's disease or multiple sclerosis. Read more about this study
- Who is it for?
- Ages 18 years and olderHealthy volunteers can take part
- What is being tested?
- [18F]PBR111, PBR111 injection and PET scan
- Type of treatment
- Injection or infusion, Medical device, Surgery or procedure
- Could I receive a placebo?
- No, everyone receives an active treatment
- How many people
- 6 participants
- Where
- 1 siteSwitzerland
- Study dates
- 24 Jun 2024to 30 Jul 2024
- Phase
- Interventional
- Are there results?
- None posted in the registry
Key requirements
Who can take part, as listed by the sponsor. Only the study team can confirm whether you are eligible, so take this list to your doctor.
- Ages 18 years and older
- All sexes
- Healthy volunteers accepted
- Adult, Older adult
Who may be able to join
- Aged ≥18 (3 male and 3 female participants)
- Fluent in French and able and willing to provide written informed consent.
Who cannot join
- Homozygosity for the rs6971 polymorphism on TSPO that results in low-affinity binding. This criterion is added because this polymorphism alters significantly the ability of the radiotracer [18F]PBR111 to bind to TSPO, hence precluding quantification.
- Absence of a stable contraceptive regimen (specifically, intrauterine contraceptive device or contraceptive treatment per os). Only women with stable contraception will be added to eliminate the risk of exposure of pregnant women and their foetus to radioactivity.
- Presence of any significant history or current diagnosis of chronic disease or syndrome (including neurological, psychiatric, cardiovascular, oncological, metabolic, rheumatological conditions).
- One or more episode(s) of acute infectious or allergic reaction in the last month before inclusion and during the study period. Again, we cannot exclude that such conditions might produce immune alterations in the brain, thus confounding the results of TSPO quantification with [18F]PBR111.
- Presence of clinically relevant laboratory abnormalities in the haematological and biochemical blood tests, as defined as laboratory values that require clinical workup and/or treatment (e.g. anaemia, hyperglycaemia, electrolyte imbalances)
- A body mass index <20 or >30 (this criterion is necessary because TSPO has been shown to be variable with respect to body mass index (113-115)).
- Exposure to research related radiation in the past five years that, when combined with this study, would place subjects above the allowable limits.
- Conditions precluding entry into the scanners (e.g. claustrophobia).
Trial locations and contacts
1 site in 1 country.
About this study
The 18 kDa translocator protein (TSPO) is a mitochondrial protein that becomes overexpressed during neuroinflammatory conditions, such as in Alzheimer's disease or multiple sclerosis. TSPO is of interest because it serves as a marker for microglial and astrocytic activity, measurable via in vivo positron emission tomography (PET) molecular imaging. [18F]PBR111 is a second-generation TSPO PET radioligand with high signal specificity but a sensitivity to TSPO polymorphism, in comparison with first-generation ligands. This study focused on the biodistribution and dosimetry of [18F]PBR111 in healthy humans.
Read the detailed description
This study investigated the whole-body biodistribution and radiation dosimetry of the second-generation TSPO radioligand [18F]PBR111 in healthy volunteers. The translocator protein (TSPO, 18 kDa) is a mitochondrial marker overexpressed in activated microglia and astrocytes during neuroinflammatory processes such as Alzheimer's disease, multiple sclerosis, and other neurological or systemic conditions. [18F]PBR111, a fluorine-18 labeled imidazopyridine derivative, offers high affinity and specificity for TSPO but is sensitive to the rs6971 polymorphism, leading to different binding classes (high- and mixed-affinity binders). Establishing accurate human dosimetry was essential before extending its clinical use.
Six healthy volunteers (3 females, 3 males) free from chronic or acute inflammatory, infectious, or allergic conditions were recruited under local ethics approval (Geneva University Hospitals). All participants underwent genotyping for the rs6971 polymorphism to confirm the absence of low-affinity binders. Each subject received approximately 200 MBq of [18F]PBR111 intravenously, synthesized via an automated AllInOne module using [18F]fluoride produced on an IBA 18.5 MeV cyclotron. Radiochemical preparation included QMA cartridge trapping, elution with tetrabutylammonium hydroxide, azeotropic drying, nucleophilic substitution with the precursor, purification by semi-preparative HPLC, and formulation through dual C18 SepPak cartridges, ethanol/saline elution, and sterilizing filtration. The final product was obtained with high radiochemical purity and molar activity.
Dynamic whole-body PET/CT was performed on a Siemens Biograph™ Vision 600 Edge using continuous bed motion and 10 sequential passes of increasing duration over ~130 minutes. Low-dose CT provided attenuation correction. PET images were reconstructed with OP-OSEM (2 iterations, 21 subsets), incorporating TOF and resolution modeling, and expressed as SUV (body weight normalized). Organ segmentation was achieved using a deep-learning model applied to PET/CT data, covering major target organs (liver, lungs, spleen, kidneys, red bone marrow, GI tract, urinary bladder, heart wall, pancreas, adrenals, thyroid, etc.), with the remainder of the body included for dosimetric completeness.
Organ time-activity curves were derived from decay-corrected PET data, integrated, and analyzed using OLINDA/EXM v2.2 to calculate residence times and absorbed doses. Effective dose estimates followed ICRP-103 methodology. Statistical analyses included Mann-Whitney tests (sex effects) and Friedman tests with Dunn's multiple comparisons (organ contributions).
- Being tested
- [18F]PBR111, PBR111 injection, PET scan, PBR111 dosimetry
What participants receive
What participants receive. In a randomised study each person is assigned to one group by chance.
[18F]PBR111Drug
Also called Preparation
[18F]PBR111 is a radiotracer produced at University Hospital of Geneva in a radiopharmaceutical GMP facility. The drug product is provided as sterile solution for intravenous injection in a glass vial containing 10 mL (max) of formulated product, the maximal applicable dose being 200 MBq.
PBR111 injectionProcedure or surgery
[18F]PBR111 will be administered once, intravenously in the antecubital fossa at a dose of 200 MBq
PET scanDevice
Upon administration of the radiotracer, a 120-minute PET/CT scan will be initiated.
PBR111 dosimetryRadiation
to establish the exposure of the organs/tissues to a standard radioactive dose (200 MBq) of [18F]PBR111
| Study group | Role | What they receive |
|---|---|---|
| Drug: radiation dosimetry and biodistribution | Experimental | 6 healthy adult volunteers (3 men and 3 women) will be assigned to the radiation dosimetry group. [18F]PBR111 will be administered once. Receives: Drug: [18F]PBR111; Procedure: PBR111 injection; Device: PET scan; Radiation: PBR111 dosimetry |
What is being measured
The primary outcome is the main question the study is designed to answer.
Measurement of radiation dosimetry and biodistribution of the translocator protein radiotracer [18F]PBR111 determined with PET/CT in healthy human volunteers (3 male and 3 female participants)
[18F]PBR111 will be manually injected as a smooth bolus followed by a 20-ml saline flush via an intravenous catheter in the antecubital fossa placed before the scan. After injecting a standard [18F]PBR111 activity of 200 MBq, PET/CT scans will be performed on a BiographTM mCT or Vision scanner (Siemens Healthcare, Erlangen, Germany). The whole duration of the scanning protocol is about 120 minutes, consisting of CT and PET dynamic acquisitions.
Measured: 6 months
Secondary outcomes (1)
Calculation of the total radiation exposure of a PET/CT with 200 MBq of [18F]PBR111
ROIs will be delineated manually using the Osirix software on a number of internal organs directly on the PET images with the help of the CT scan for radiation dosimetry calculations. The selected ROIs will be whole brain, left and right lung and kidney, liver, heart wall, spleen, bladder, bone marrow and organs displaying an activity concentration above background. The delineated ROIs will then be copied on all dynamic PET series to extract the time activity curves (TACs) for each organ/tissue. The total number of disintegrations (formerly referred to as residence times) will be extracted and used as input to the OLINDA/EXM software to estimate the radiation dose to organs and the effective dose to the reference adult male from mimicking the adult subjects enrolled in the study protocol.
Measured: 6 months
Timeline
From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.
- First posted3 May 2024
- Study start24 Jun 2024
- Primary completion30 Jul 2024
- Study completion30 Jul 2024
Resources
- Official record on ClinicalTrials.govThe registry entry this page is built from, with its full change history.
- Publications (1)Papers the sponsor has linked to this study.
- Other trials for DosimetryStudies of the same condition, open and under way.
- What the trial phases meanHow a treatment moves from first tests in people to approval.
More details
For doctors and researchers: how the study is designed, who runs it, and its registry IDs.
Study design
- Study type
- Interventional
- Phase
- Phase N/A
- Primary purpose
- Basic science
- Allocation
- Not applicable
- Intervention model
- Single group
- Masking
- None (open label)
- Enrolment
- 6 participants (actual)
Sponsor and investigators
- Lead sponsor
- Prof. Daniele Zullino
- Sponsor type
- University, hospital or other
- Responsible party
- Sponsor-investigator, Prof. Daniele Zullino, University Hospital, Geneva
IDs, dates and publications
- ClinicalTrials.gov ID
- NCT06398392
- Sponsor's protocol ID
- 2022-00542
- Status last verified
- Sep 2025
- First submitted
- 23 Apr 2024
- Last updated
- 16 Sep 2025
- Results posted
- No
- Data monitoring committee
- Yes
- FDA-regulated drug
- No
- FDA-regulated device
- No
- Individual data sharing
- No
Publications
Tournier BB, Mansouri Z, Salimi Y, Ceyzeriat K, Mathoux G, Richard-Lepouriel H, Zullino D, Bois F, Zaidi H, Garibotto V, Tsartsalis S, Millet P. Radiation dosimetry of the 18 kDa translocator protein ligand [18F]PBR111 in humans. Nucl Med Biol. 2025 May-Jun;144-145:109011. doi: 10.1016/j.nucmedbio.2025.109011. Epub 2025 Mar 29.
PubMed 40179687
Study at a glance
From the registry record, last updated by the sponsor on 16 Sep 2025. Recruitment status is as the sponsor reported it: confirm with the study team.
- Official title
- Radiation Dosimetry of the 18 kDa Translocator Protein Ligand [18F]PBR111 in Humans
- ClinicalTrials.gov ID
- NCT06398392
- Acronym / sponsor ID
- 2022-00542
- Study type
- Interventional
- Recruitment status
- Completed
- Enrolment
- 6 participants (actual)
- Lead sponsor
- Prof. Daniele ZullinoUniversity, hospital or other
- Study start
- 24 Jun 2024 (actual)
- Primary completion
- 30 Jul 2024 (actual)
- Study completion
- 30 Jul 2024 (actual)
- First posted
- 3 May 2024 (actual)
- Results
- Not posted in the source record
Clinical summary
The research question as the sponsor registered it. This describes what the study plans to test, not what it found.
The 18 kDa translocator protein (TSPO) is a mitochondrial protein that becomes overexpressed during neuroinflammatory conditions, such as in Alzheimer's disease or multiple sclerosis. TSPO is of interest because it serves as a marker for microglial and astrocytic activity, measurable via in vivo positron emission tomography (PET) molecular imaging. [18F]PBR111 is a second-generation TSPO PET radioligand with high signal specificity but a sensitivity to TSPO polymorphism, in comparison with first-generation ligands. This study focused on the biodistribution and dosimetry of [18F]PBR111 in healthy humans.
Detailed description
This study investigated the whole-body biodistribution and radiation dosimetry of the second-generation TSPO radioligand [18F]PBR111 in healthy volunteers. The translocator protein (TSPO, 18 kDa) is a mitochondrial marker overexpressed in activated microglia and astrocytes during neuroinflammatory processes such as Alzheimer's disease, multiple sclerosis, and other neurological or systemic conditions. [18F]PBR111, a fluorine-18 labeled imidazopyridine derivative, offers high affinity and specificity for TSPO but is sensitive to the rs6971 polymorphism, leading to different binding classes (high- and mixed-affinity binders). Establishing accurate human dosimetry was essential before extending its clinical use.
Six healthy volunteers (3 females, 3 males) free from chronic or acute inflammatory, infectious, or allergic conditions were recruited under local ethics approval (Geneva University Hospitals). All participants underwent genotyping for the rs6971 polymorphism to confirm the absence of low-affinity binders. Each subject received approximately 200 MBq of [18F]PBR111 intravenously, synthesized via an automated AllInOne module using [18F]fluoride produced on an IBA 18.5 MeV cyclotron. Radiochemical preparation included QMA cartridge trapping, elution with tetrabutylammonium hydroxide, azeotropic drying, nucleophilic substitution with the precursor, purification by semi-preparative HPLC, and formulation through dual C18 SepPak cartridges, ethanol/saline elution, and sterilizing filtration. The final product was obtained with high radiochemical purity and molar activity.
Dynamic whole-body PET/CT was performed on a Siemens Biograph™ Vision 600 Edge using continuous bed motion and 10 sequential passes of increasing duration over ~130 minutes. Low-dose CT provided attenuation correction. PET images were reconstructed with OP-OSEM (2 iterations, 21 subsets), incorporating TOF and resolution modeling, and expressed as SUV (body weight normalized). Organ segmentation was achieved using a deep-learning model applied to PET/CT data, covering major target organs (liver, lungs, spleen, kidneys, red bone marrow, GI tract, urinary bladder, heart wall, pancreas, adrenals, thyroid, etc.), with the remainder of the body included for dosimetric completeness.
Organ time-activity curves were derived from decay-corrected PET data, integrated, and analyzed using OLINDA/EXM v2.2 to calculate residence times and absorbed doses. Effective dose estimates followed ICRP-103 methodology. Statistical analyses included Mann-Whitney tests (sex effects) and Friedman tests with Dunn's multiple comparisons (organ contributions).
Study design
- Primary purpose
- Basic science
- Allocation
- Not applicable
- Intervention model
- Single group
- Masking
- None (open label)
- Number of arms
- 1
| Arm | Type | Receives |
|---|---|---|
| Drug: radiation dosimetry and biodistribution | Experimental | Drug: [18F]PBR111, Procedure: PBR111 injection, Device: PET scan, Radiation: PBR111 dosimetry6 healthy adult volunteers (3 men and 3 women) will be assigned to the radiation dosimetry group. [18F]PBR111 will be administered once. |
Who may qualify
- Ages
- 18 years and older
- Sex
- All
- Healthy volunteers
- Accepted
- Age groups
- Adult, Older adult
Key inclusion criteria (2 listed)
- Aged ≥18 (3 male and 3 female participants)
- Fluent in French and able and willing to provide written informed consent.
Key exclusion criteria (8 listed)
- Homozygosity for the rs6971 polymorphism on TSPO that results in low-affinity binding. This criterion is added because this polymorphism alters significantly the ability of the radiotracer [18F]PBR111 to bind to TSPO, hence precluding quantification.
- Absence of a stable contraceptive regimen (specifically, intrauterine contraceptive device or contraceptive treatment per os). Only women with stable contraception will be added to eliminate the risk of exposure of pregnant women and their foetus to radioactivity.
- Presence of any significant history or current diagnosis of chronic disease or syndrome (including neurological, psychiatric, cardiovascular, oncological, metabolic, rheumatological conditions).
- One or more episode(s) of acute infectious or allergic reaction in the last month before inclusion and during the study period. Again, we cannot exclude that such conditions might produce immune alterations in the brain, thus confounding the results of TSPO quantification with [18F]PBR111.
- Presence of clinically relevant laboratory abnormalities in the haematological and biochemical blood tests, as defined as laboratory values that require clinical workup and/or treatment (e.g. anaemia, hyperglycaemia, electrolyte imbalances)
Eligibility is decided by the study team after screening; this overview does not establish that a patient qualifies. Full inclusion and exclusion criteria.
Interventions
| Intervention | Type | Arms |
|---|---|---|
| [18F]PBR111Also: Preparation[18F]PBR111 is a radiotracer produced at University Hospital of Geneva in a radiopharmaceutical GMP facility. The drug product is provided as sterile solution for intravenous injection in a glass vial containing 10 mL (max) of formulated product, the maximal applicable dose being 200 MBq. | Drug | Drug: radiation dosimetry and biodistribution |
| PBR111 injection[18F]PBR111 will be administered once, intravenously in the antecubital fossa at a dose of 200 MBq | Procedure or surgery | Drug: radiation dosimetry and biodistribution |
| PET scanUpon administration of the radiotracer, a 120-minute PET/CT scan will be initiated. | Device | Drug: radiation dosimetry and biodistribution |
| PBR111 dosimetryto establish the exposure of the organs/tissues to a standard radioactive dose (200 MBq) of [18F]PBR111 | Radiation | Drug: radiation dosimetry and biodistribution |
Primary outcome
Measurement of radiation dosimetry and biodistribution of the translocator protein radiotracer [18F]PBR111 determined with PET/CT in healthy human volunteers (3 male and 3 female participants)
Time frame: 6 months
[18F]PBR111 will be manually injected as a smooth bolus followed by a 20-ml saline flush via an intravenous catheter in the antecubital fossa placed before the scan. After injecting a standard [18F]PBR111 activity of 200 MBq, PET/CT scans will be performed on a BiographTM mCT or Vision scanner (Siemens Healthcare, Erlangen, Germany). The whole duration of the scanning protocol is about 120 minutes, consisting of CT and PET dynamic acquisitions.
1 secondary outcome
Calculation of the total radiation exposure of a PET/CT with 200 MBq of [18F]PBR111
Time frame: 6 months
Results and safety
The study is completed, but results are not available in the source record. That does not mean the treatment did or did not work.
Research links
- Official record on ClinicalTrials.govLast updated by the sponsor 16 Sep 2025.
- Results publication: PubMed 40179687Tournier BB, Mansouri Z, Salimi Y, Ceyzeriat K, Mathoux G, Richard-Lepouriel H, Zullino D, Bois F, Zaidi H, Garibotto V, Tsartsalis S, Millet P. Radiation dosimetry of the 18 kDa translocator protein ligand [18F]PBR111 in humans. Nucl Med Biol. 2025 May-Jun;144-145:109011. doi: 10.1016/j.nucmedbio.2025.109011. Epub 2025 Mar 29.
- Individual participant dataSharing planned: No
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Referral and contact
AzTrials does not enrol participants or take referrals. Contact the study team or a site listed below; they decide who can take part. This study is not recruiting at the moment.
The record lists no contact. Use the official record to reach the sponsor.
1 site in 1 country: see every site and its status.
Questions about this trial
What is this clinical trial studying?
A study testing [18F]PBR111, PBR111 injection and PET scan in people with Dosimetry and Healthy, run by Prof. Daniele Zullino at 1 site in Switzerland.
The full registered description is in the About this study section and the official record.
Who may be eligible to take part?
The sponsor lists 2 inclusion and 8 exclusion criteria. Eligibility is decided by the study team after screening, so read the full criteria and contact a listed site.
Is this clinical trial currently recruiting?
The record says: finished, as of the sponsor's last update on 16 Sep 2025. Status can change between updates, so confirm with the study contact before making plans.
Where is the study taking place?
The record lists 1 site in Switzerland. Whether a site is taking part right now should be confirmed with that site. See every site.
What are the possible benefits and risks?
They depend on the study and the treatment, and no study can promise a benefit. The study team explains the known risks during informed consent, before anyone joins; the record itself does not list them.
Are results available for this study?
The study is completed, but results are not available in the source record. That does not mean the treatment did or did not work.
How can a doctor refer a patient or contact the research team?
The record lists no contact. The official record names the sponsor, who can be asked directly. AzTrials does not enrol participants or take referrals.
What does the primary outcome measure?
Measurement of radiation dosimetry and biodistribution of the translocator protein radiotracer [18F]PBR111 determined with PET/CT in healthy human volunteers (3 male and 3 female participants) (time frame: 6 months). It is what the study was designed to measure, not a finding.
Where can I read the original study information?
On the ClinicalTrials.gov record for NCT06398392, which also lists 1 linked publication.
Does a listing mean the treatment is approved or proven to work?
No. A listing means the study is registered. It does not show that the treatment is safe, works, or is approved by a regulator.
How often is this information updated?
AzTrials copies changed records from ClinicalTrials.gov every night and reloads the whole registry every week. The sponsor last updated this record on 16 Sep 2025.