Healthy Volunteers - Male and FemaleNCT07362290
TSPO Occupancy in the Human Lung
A study testing XBD173 in people with Healthy Volunteers - Male and Female, run by Imperial College London at 1 site in United Kingdom.
Trial summary
The investigators would like to explore the role of TSPO in PAH using a pharmacological challenge agent (XBD173) to modulate TSPO function. In order to appropriately design experimental medicine studies examining TSPO function, the investigators first need an understanding of the relationship between XBD173 dose and… Read more about this study
- Who is it for?
- Ages 25 to 75 yearsHealthy volunteers can take part
- Conditions the study is for
- Healthy Volunteers - Male and Female
- What is being tested?
- XBD173
- Type of treatment
- Pill or oral medicine
- Could I receive a placebo?
- No, everyone receives an active treatment
- How many people
- 16 participants
- Where
- 1 siteUnited Kingdom
- Study dates
- 19 Sep 2025to 31 Mar 2027
- Phase
- Interventional
- Are there results?
- Not yet: the study is under way
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 25 to 75 years
- All sexes
- Healthy volunteers accepted
- Adult, Older adult
Who may be able to join
- Subjects aged between 25-75 years old
- Able to provide written informed consent prior to any study mandated procedures
- Able to lie comfortably on back for up to 90 minutes at a time (Part A only)
- Female participants of childbearing potential are eligible to participate after a negative highly sensitive pregnancy test if they are taking a highly effective method of contraception during participation in the study and until the end of relevant systemic exposure. The following methods are permitted:
- progesterone implant
- intrauterine device (also called IUD)
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- intrauterine hormone-releasing system (also known as IUS)
- bilateral tubal occlusion
- vasectomised partner
- sexual abstinence
- Male participants who are fertile are eligible to participate if they are willing to comply with the contraceptive requirements as listed above *Definition of fertile females (women of childbearing potential) and of fertile men: For the purpose of this document, a woman is considered of childbearing potential, i.e. fertile, following menarche and until becoming post-menopausal unless permanently sterile. Permanent sterilisation methods include hysterectomy, bilateral salpingectomy and bilateral oophorectomy. A postmenopausal state is defined as no menses for 12 months without an alternative medical cause. A high follicle stimulating hormone (FSH) level in the postmenopausal range may be used to confirm a post-menopausal state in women not using hormonal contraception or hormonal replacement therapy. However in the absence of 12 months of amenorrhea, a single FSH measurement is insufficient. For the purpose of this document, a man is considered fertile after puberty unless their medical notes document that they are permanently sterile.
Who cannot join
- Unable to provide informed consent and/or are non-fluent speakers of the English language
- Hypersensitivity to XBD173 or to any of the excipients
- Clinically-significant renal disease (confirmed by creatinine clearance <30 ml/min per 1.73m2)
- Clinically-significant liver disease (confirmed by serum transaminases >3 times than upper normal limit)
- History of uncontrolled systemic hypertension
- Acute infection (including eye, dental, and skin infections)
Show all 19Show fewer
- History of chronic inflammatory disease including HIV, and Hepatitis B
- Women who are pregnant or breastfeeding
- Patients who have received an Investigational Medicinal Product (IMP) within 5 half-lives of the last dose of the IMP or 1 month (which ever is greater) before the baseline visit
- Diagnosis of any condition which may directly or indirectly lead to lung pathology in the opinion of the investigator
- Severe and moderate P450 CY3A4 inhibitors
- o Boceprevir, Clarithromycin, Cobicistat, Idelalisib, Itraconazole, Ketoconazole, Nelfinavir, Ritonavir, Saquinavir, Telaprevir, Telithromycin, Voriconazoleb, Aprepitant, Conivaptan, Crizotinib, Diltiazem, Dronedarone, Erythromycin, Fluconazole, Imatinib, Isavuconazole, Nefazodone, Netupitant, Nilotinib, Posaconazolee, Tofisopam, Verapamil, Delavirdine.
- Severe and moderate P450 CY3A4 inducers
- o Carbamazepine, Enzalutamide, Fosphenytoin, Mitotane, Phenytoin, Rifampicin, Bosentan, Efavirenz, St John's wort, Barbiturates, Nevirapine, Primidone, Rifabutin, Rifapentine.
- Part A (PET imaging) specific exclusion criteria
- TT/AT Genotype at the rs6971 locus
- Previous participation in a research study involving ionising radiation such that in combination with this study the radiation exposure over the last 12 months would exceed 10 mSv
- Positive Allen's test
- Use of Oral anticoagulants or antiplatelet agents other than low dose aspirin
Trial locations and contacts
1 site in 1 country. Contact the study team or a site near you to ask about taking part.
About this study
The investigators would like to explore the role of TSPO in PAH using a pharmacological challenge agent (XBD173) to modulate TSPO function. In order to appropriately design experimental medicine studies examining TSPO function, the investigators first need an understanding of the relationship between XBD173 dose and occupancy of lung TSPO.
The aim of the proposed study, therefore, is to answer three questions:
Read more
- What plasma concentrations of XBD173 are required to cause high occupancy of lung TSPO?
- What doses of XBD173 are required to achieve these plasma concentrations at steady state?
- Does taking XBD173 with food affect the plasma concentrations achieved?
Part A will address question (1). In part A, the investigators will use positron emission tomography (PET) imaging with the TSPO targeting PET ligand [11C]PBR28 to quantify the amount of TSPO in the lung. The investigators will then administer XBD173 orally (between 10mg and 90mg), and perform two subsequent [11C]PBR28 PET scans. XBD173 and [11C]PBR28 both bind the same site on the TSPO, and therefore compete with each other for TSPO binding. This allows for quantification of TSPO occupancy by XBD173. Measuring XBD173 plasma concentrations during the PET scan will allow the investigators to learn how much XBD173 is required in the plasma to produce a certain degree of TSPO occupancy in the lung. Using a wide range of doses (10mg-90mg) and scan times ensures that some participants will have high TSPO occupancy and some will have low TSPO occupancy. This will allow the investigators to better understand the plasma concentration/occupancy relationship.
Part B will address questions (2) and (3), i.e what doses of XBD173 are required to achieve the plasma concentration leading to high TSPO occupancy at steady state (to be determined in Part A), and does taking XBD173 with food affect the plasma concentrations achieved? The investigators assume that the plasma concentrations required to cause high TSPO occupancy (identified in Part A) will be achieved with a dose of approximately 60mg. Therefore, in Part B for study visits 1, 2 and 3, participants will receive 6 doses of 60mg XBD173 spread over 3 days and the effect of food investigated by dosing with and without food.
In Part A at Study Visit 1, a [11C]-PBR28 PET scan will be performed under baseline conditions. XBD173 will then be administered (10-90mg, oral) on study visits 2 and 3 and two further PET scans will be performed post dosing to understand how long the drug blocks the binding of the PET tracer.
The first two participants will be dosed with 10-90mg. The dose and scan times for remaining subjects will be based on occupancy and plasma drug level data for previous subjects.
In Part B at Study Visit 1, participants will arrive fasted in the morning. After placement of a venous cannula will then be dosed with a single dose of oral XBD173 (60mg). Blood samples will be taken at up to 12 timepoints over 8 hours. At Study Visit 2, participants will arrive fasted in the morning. They will be given a standard breakfast and the procedures of Study Visit 1 will be repeated, with dosing occurring within 15 mins of finishing breakfast. They will receive a second dose of XBD173 (60mg) whilst at the ICRF 6-8 hours after the first dose, having had lunch. Participants will then be given a further dose to take at home that night prior to bed. At Study Visit 3, which will occur on the following day, participants will arrive in the morning fasted and will be given a standard breakfast. After placement of a venous cannula, they will be dosed orally with XBD173 (60mg) in the morning and again 6-8 hours later, and blood samples taken throughout the day.
Study visits 4, 5 and 6 will be identical to Study visits 1,2 and 3 respectively, but for the dose of XBD173 which will be 40mg or 90mg depending on the plasma levels obtained with 60mg.
- Conditions
- Healthy Volunteers - Male and Female
- Being tested
- XBD173
What participants receive
What participants receive. In a randomised study each person is assigned to one group by chance.
XBD173Drug
Small molecule experimental medication binding to mitochondrial protein TSPO
| Study group | Role | What they receive |
|---|---|---|
| The TSPO signal in the lungs of healthy individuals, in the presence and absence of XBD173 | Other | In part A, the investigators will use positron emission tomography (PET) imaging with the TSPO targeting PET ligand [11C]PBR28 to quantify the amount of TSPO in the lung. The investigators will then administer XBD173 orally (between 10mg and 90mg), and perform two subsequent [11C]PBR28 PET scans spread between two and 24 hours post dosing. XBD173 and [11C]PBR28 both bind the same site on the TSPO, and therefore compete with each other for TSPO binding. This allows for quantification of TSPO occupancy by XBD173. Measuring XBD173 plasma concentrations during the PET scan will allow us to learn how much XBD173 is required in the plasma to produce a certain degree of TSPO occupancy in the lung. Using a wide range of doses (10mg-90mg) and scan times (2-24 hours) ensures that some participants will have high TSPO occupancy and some will have low TSPO occupancy. This will allow us to better understand the plasma concentration/occupancy relationship. Receives: Drug: XBD173 |
| Plasma concentrations of XBD173 following oral dosing (in fasting and fed states) | Other | Part B will look at what doses of XBD173 are required to achieve the plasma concentration leading to high TSPO occupancy at steady state (to be determined in Part A), and whether taking XBD173 with food affects the plasma concentrations achieved. The investigatorsassume that the plasma concentrations required to cause high TSPO occupancy (identified in Part A) will be achieved with a dose of approximately 60mg. Therefore, in Part B for study visits 1, 2 and 3, participants will receive 6 doses of 60mg XBD173 spread over 3 days and the effect of food investigated by dosing with and without food. Receives: Drug: XBD173 |
What is being measured
The primary outcome is the main question the study is designed to answer.
To establish the relationship between plasma concentration of XBD173 and TSPO occupancy in the human lung
This will be achieved by measuring the [11C]PBR28 signal in the lungs of healthy individuals in the presence and absence of XBD173. We will use Occupancy % to measure this outcome. [11C]PBR28 signal in the lungs will be measured by volume of distribution.
Measured: Up to 4 months
Secondary outcomes (1)
To establish the relationship between dose of XBD173 and plasma concentration of XBD173 at steady state , fed state and fasted state.
This will be achieved by measuring the XBD173 plasma concentration at steady state, fed state and fasted state.
Measured: Up to 1 week
Timeline
From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.
- First posted23 Jan 2026
- Study start19 Sep 2025
- Primary completion2 Feb 2026
- Study completion31 Mar 2027 (estimated)
Resources
- Official record on ClinicalTrials.govThe registry entry this page is built from, with its full change history.
- Other trials for Healthy Volunteers - Male and FemaleStudies of the same condition, open and under way.
- More trials run by Imperial College LondonThe sponsor's other registered studies.
- 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
- Non-randomised
- Intervention model
- Single group
- Model description
- Part A will look at the TSPO signal in the lungs of participants, in the presence and absence of a drug to block the specific binding of the PET signal (XBD173). Part B will look at plasma concentrations of XBD173 following oral dosing (in fasting and fed states). This is a single group assignment where participants can take part in both Part A and Part B, or Part A alone, or Part B alone. Parts A and B will run concurrently
- Masking
- None (open label)
- Enrolment
- 16 participants (estimated)
Sponsor and investigators
- Lead sponsor
- Imperial College London
- Sponsor type
- University, hospital or other
- Responsible party
- Sponsor
IDs, dates and publications
- ClinicalTrials.gov ID
- NCT07362290
- Sponsor's protocol ID
- 24/YH/0091
- Status last verified
- May 2026
- First submitted
- 30 Sep 2025
- Last updated
- 1 Jun 2026
- Results posted
- No
- Data monitoring committee
- No
- FDA-regulated drug
- No
- FDA-regulated device
- No
- Individual data sharing
- No
Study at a glance
From the registry record, last updated by the sponsor on 1 Jun 2026. Recruitment status is as the sponsor reported it: confirm with the study team.
- Official title
- TSPO Occupancy in the Human Lung
- ClinicalTrials.gov ID
- NCT07362290
- Acronym / sponsor ID
- 24/YH/0091
- Conditions
- Healthy Volunteers - Male and Female
- Study type
- Interventional
- Recruitment status
- Enrolling by invitation
- Enrolment
- 16 participants (estimated)
- Lead sponsor
- Imperial College LondonUniversity, hospital or other
- Study start
- 19 Sep 2025 (actual)
- Primary completion
- 2 Feb 2026 (actual)
- Study completion
- 31 Mar 2027 (estimated)
- First posted
- 23 Jan 2026 (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 investigators would like to explore the role of TSPO in PAH using a pharmacological challenge agent (XBD173) to modulate TSPO function. In order to appropriately design experimental medicine studies examining TSPO function, the investigators first need an understanding of the relationship between XBD173 dose and occupancy of lung TSPO.
The aim of the proposed study, therefore, is to answer three questions:
- What plasma concentrations of XBD173 are required to cause high occupancy of lung TSPO?
- What doses of XBD173 are required to achieve these plasma concentrations at steady state?
- Does taking XBD173 with food affect the plasma concentrations achieved?
Part A will address question (1). In part A, the investigators will use positron emission tomography (PET) imaging with the TSPO targeting PET ligand [11C]PBR28 to quantify the amount of TSPO in the lung. The investigators will then administer XBD173 orally (between 10mg and 90mg), and perform two subsequent [11C]PBR28 PET scans. XBD173 and [11C]PBR28 both bind the same site on the TSPO, and therefore compete with each other for TSPO binding. This allows for quantification of TSPO occupancy by XBD173. Measuring XBD173 plasma concentrations during the PET scan will allow the investigators to learn how much XBD173 is required in the plasma to produce a certain degree of TSPO occupancy in the lung. Using a wide range of doses (10mg-90mg) and scan times ensures that some participants will have high TSPO occupancy and some will have low TSPO occupancy. This will allow the investigators to better understand the plasma concentration/occupancy relationship.
Part B will address questions (2) and (3), i.e what doses of XBD173 are required to achieve the plasma concentration leading to high TSPO occupancy at steady state (to be determined in Part A), and does taking XBD173 with food affect the plasma concentrations achieved? The investigators assume that the plasma concentrations required to cause high TSPO occupancy (identified in Part A) will be achieved with a dose of approximately 60mg. Therefore, in Part B for study visits 1, 2 and 3, participants will receive 6 doses of 60mg XBD173 spread over 3 days and the effect of food investigated by dosing with and without food.
In Part A at Study Visit 1, a [11C]-PBR28 PET scan will be performed under baseline conditions. XBD173 will then be administered (10-90mg, oral) on study visits 2 and 3 and two further PET scans will be performed post dosing to understand how long the drug blocks the binding of the PET tracer.
The first two participants will be dosed with 10-90mg. The dose and scan times for remaining subjects will be based on occupancy and plasma drug level data for previous subjects.
In Part B at Study Visit 1, participants will arrive fasted in the morning. After placement of a venous cannula will then be dosed with a single dose of oral XBD173 (60mg). Blood samples will be taken at up to 12 timepoints over 8 hours. At Study Visit 2, participants will arrive fasted in the morning. They will be given a standard breakfast and the procedures of Study Visit 1 will be repeated, with dosing occurring within 15 mins of finishing breakfast. They will receive a second dose of XBD173 (60mg) whilst at the ICRF 6-8 hours after the first dose, having had lunch. Participants will then be given a further dose to take at home that night prior to bed. At Study Visit 3, which will occur on the following day, participants will arrive in the morning fasted and will be given a standard breakfast. After placement of a venous cannula, they will be dosed orally with XBD173 (60mg) in the morning and again 6-8 hours later, and blood samples taken throughout the day.
Study visits 4, 5 and 6 will be identical to Study visits 1,2 and 3 respectively, but for the dose of XBD173 which will be 40mg or 90mg depending on the plasma levels obtained with 60mg.
Study design
- Primary purpose
- Basic science
- Allocation
- Non-randomised
- Intervention model
- Single group
- Masking
- None (open label)
- Number of arms
- 2
- Model description
- Part A will look at the TSPO signal in the lungs of participants, in the presence and absence of a drug to block the specific binding of the PET signal (XBD173). Part B will look at plasma concentrations of XBD173 following oral dosing (in fasting and fed states). This is a single group assignment where participants can take part in both Part A and Part B, or Part A alone, or Part B alone. Parts A and B will run concurrently
| Arm | Type | Receives |
|---|---|---|
| The TSPO signal in the lungs of healthy individuals, in the presence and absence of XBD173 | Other | Drug: XBD173In part A, the investigators will use positron emission tomography (PET) imaging with the TSPO targeting PET ligand [11C]PBR28 to quantify the amount of TSPO in the lung. The investigators will then administer XBD173 orally (between 10mg and 90mg), and perform two subsequent [11C]PBR28 PET scans spread between two and 24 hours post dosing. XBD173 and [11C]PBR28 both bind the same site on the TSPO, and therefore compete with each other for TSPO binding. This allows for quantification of TSPO occupancy by XBD173. Measuring XBD173 plasma concentrations during the PET scan will allow us to learn how much XBD173 is required in the plasma to produce a certain degree of TSPO occupancy in the lung. Using a wide range of doses (10mg-90mg) and scan times (2-24 hours) ensures that some participants will have high TSPO occupancy and some will have low TSPO occupancy. This will allow us to better understand the plasma concentration/occupancy relationship. |
| Plasma concentrations of XBD173 following oral dosing (in fasting and fed states) | Other | Drug: XBD173Part B will look at what doses of XBD173 are required to achieve the plasma concentration leading to high TSPO occupancy at steady state (to be determined in Part A), and whether taking XBD173 with food affects the plasma concentrations achieved. The investigatorsassume that the plasma concentrations required to cause high TSPO occupancy (identified in Part A) will be achieved with a dose of approximately 60mg. Therefore, in Part B for study visits 1, 2 and 3, participants will receive 6 doses of 60mg XBD173 spread over 3 days and the effect of food investigated by dosing with and without food. |
Who may qualify
- Ages
- 25 to 75 years
- Sex
- All
- Healthy volunteers
- Accepted
- Age groups
- Adult, Older adult
Key inclusion criteria (11 listed)
- Subjects aged between 25-75 years old
- Able to provide written informed consent prior to any study mandated procedures
- Able to lie comfortably on back for up to 90 minutes at a time (Part A only)
- Female participants of childbearing potential are eligible to participate after a negative highly sensitive pregnancy test if they are taking a highly effective method of contraception during participation in the study and until the end of relevant systemic exposure. The following methods are permitted:
- progesterone implant
Key exclusion criteria (19 listed)
- Unable to provide informed consent and/or are non-fluent speakers of the English language
- Hypersensitivity to XBD173 or to any of the excipients
- Clinically-significant renal disease (confirmed by creatinine clearance <30 ml/min per 1.73m2)
- Clinically-significant liver disease (confirmed by serum transaminases >3 times than upper normal limit)
- History of uncontrolled systemic hypertension
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 |
|---|---|---|
| XBD173Small molecule experimental medication binding to mitochondrial protein TSPO | Drug | Plasma concentrations of XBD173 following oral dosing (in fasting and fed states), The TSPO signal in the lungs of healthy individuals, in the presence and absence of XBD173 |
Primary outcome
To establish the relationship between plasma concentration of XBD173 and TSPO occupancy in the human lung
Time frame: Up to 4 months
This will be achieved by measuring the [11C]PBR28 signal in the lungs of healthy individuals in the presence and absence of XBD173. We will use Occupancy % to measure this outcome. [11C]PBR28 signal in the lungs will be measured by volume of distribution.
1 secondary outcome
To establish the relationship between dose of XBD173 and plasma concentration of XBD173 at steady state , fed state and fasted state.
Time frame: Up to 1 week
Results and safety
This study is still under way. Results are not available in the source record yet.
Research links
- Official record on ClinicalTrials.govLast updated by the sponsor 1 Jun 2026.
- 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.
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 XBD173 in people with Healthy Volunteers - Male and Female, run by Imperial College London at 1 site in United Kingdom.
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 11 inclusion and 19 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: enrolling by invitation, as of the sponsor's last update on 1 Jun 2026. 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 United Kingdom. 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?
This study is still under way. Results are not available in the source record yet.
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?
To establish the relationship between plasma concentration of XBD173 and TSPO occupancy in the human lung (time frame: Up to 4 months). It is what the study was designed to measure, not a finding.
Where can I read the original study information?
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 1 Jun 2026.