Healthy VolunteerEarly Phase 1NCT07774650
A Study of the Pharmacokinetics, Biodistribution and Dosimetry of Granzyme-B Targeted [Cu-64]-Labeled PET Radiotracers in Adult Healthy Volunteers
A Early Phase 1 study testing Granzyme-B targeted [64Cu]-labeled PET radiotracer in people with Healthy Volunteer, run by Ratio Therapeutics, Inc. at 1 site in United States.
Trial summary
This is an exploratory clinical study of copper-64 [Cu-64]-labeled granzyme B (GzmB)-targeted compounds for PET/CT imaging. The goal is to determine how GzmB-Targeted [Cu-64]-labeled compounds are distributed in the body by assessing PET/CT images and blood samples, and to assess the safety profile after a single… Read more about this study
- Who is it for?
- Ages 18 to 60 yearsHealthy volunteers can take part
- Conditions the study is for
- Healthy Volunteer
- What is being tested?
- Granzyme-B targeted [64Cu]-labeled PET radiotracer
- Type of treatment
- Injection or infusion
- Could I receive a placebo?
- No, everyone receives an active treatment
- How many people
- 12 participants
- Where
- 1 siteUnited States
- Study dates
- 8 Jul 2026to Dec 2026
- Phase
- Early Phase 1
- 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 18 to 60 years
- All sexes
- Healthy volunteers accepted
- Adult
Who may be able to join
- Adult male or female participants 18-60 years of age judged to be in good health by the Investigator
- No clinically significant laboratory abnormalities; all tests of liver and kidney function within normal limits
- Capable of giving signed informed consent, which includes compliance with requirements and restrictions listed in the ICF and this protocol
- Female participants of childbearing potential and male participants who are fertile and have female partners of childbearing potential must agree to use adequate birth control throughout the study to the conclusion of follow-up.
Who cannot join
- Pregnant or breast-feeding female participants (female participants of childbearing potential must have negative pregnancy tests at Screening and pre-dose Day 0)
- Inadequate venous access (at least two distinct access sites allowing for separate test agent administration and PK blood sampling are required)
- Inability or unwillingness to undergo serial PET/CT imaging
- Active infection or malignancy
- Known or suspected inflammatory, autoimmune or fibrotic disease
- Major surgery or other intensive medical treatment in the 3 months prior to planned study injection, as assessed by the investigator
Show all 11Show fewer
- Received a radioisotope within 7 physical half-lives of that radioisotope prior to planned study injection
- Known allergy/hypersensitivity to PET/CT tracers or compounds similar to GzmB-Targeted Compounds
- Concurrent participation in a clinical trial of investigational product(s)
- Participation in other research protocols or clinical care where there was radiation exposure such that the exposure from the last year, in addition to the radiation exposure expected from participation in this clinical study, exceeds the effective dose of 50 mSv, which would be above the acceptable annual limit established by US federal guidelines
- Significant intercurrent illness or psychiatric illness/social situation that could place the participant at undue risk during study participation, significantly alter study outcomes, or affect participant compliance with study requirements for dosing and evaluation, as determined by the investigator
Trial locations and contacts
1 site in 1 country. Contact the study team or a site near you to ask about taking part.
United States1 site, 1 recruiting
- Recruiting
Xing Imaging
New Haven, Connecticut, 06510
About this study
Official title: A Phase 0 Study of the Pharmacokinetics, Biodistribution and Radiation Dosimetry of Granzyme-B Targeted [Cu-64]-Labeled Positron Emission Tomography (PET) Radiotracers in Adult Healthy Volunteers
This is an exploratory clinical study of copper-64 [Cu-64]-labeled granzyme B (GzmB)-targeted compounds for PET/CT imaging. The goal is to determine how GzmB-Targeted [Cu-64]-labeled compounds are distributed in the body by assessing PET/CT images and blood samples, and to assess the safety profile after a single intravenous dose.
Up to 6 healthy volunteers (3 female, 3 male) will receive one injection of a GzmB-targeted [Cu-64]-labeled compound, then undergo multiple whole-body PET/CT scans, blood and urine tests over about 24 hours, and a follow-up phone call around Day 7. Up to 2 GzmB-Targeted [Cu-64]-labeled compounds may be assessed (i.e. maximum of 12 healthy volunteers in total in the study).
Researchers will look at the blood activity of GzmB-Targeted [Cu-64]-labeled compound and the organ distribution and movement of the product in the body. They will also evaluate any changes in physical examination assessments, vital signs, ECG, and clinical laboratory measurements from pre-administration to post-administration.
Read the detailed description
Granzyme B (GzmB) is a cytotoxic serine protease released by activated T cells and natural killer cells, and its release acts as a functional marker of immune engagement. GzmB-Targeted [Cu-64]-labeled compounds are being developed as PET/CT tracers to image immune activation and inflammation. This first-in-human Phase 0 study in adult healthy volunteers is designed to characterize the pharmacokinetics, biodistribution, radiation dosimetry, and safety of GzmB-targeted [Cu-64]-labeled compounds.
Up to 6 participants (3 female, 3 male) will receive a single dose of a GzmB-targeted [Cu-64]-labeled compound, followed by serial whole-body PET/CT imaging, blood and urine sampling for pharmacokinetics and excretion, and safety assessments over approximately 24 hours post-dose, with a telephone follow-up at about 7 days. Up to 2 GzmB-Targeted [Cu-64]-labeled compounds may be assessed in the clinical trial (i.e. a maximum of 12 healthy volunteers in total in the study).
Data from this study will support lead candidate selection and inform further clinical development of a [Cu-64]-labeled GzmB-targeted imaging agent.
- Conditions
- Healthy Volunteer
- Being tested
- Granzyme-B targeted [64Cu]-labeled PET radiotracer
What participants receive
What participants receive. In a randomised study each person is assigned to one group by chance.
Granzyme-B targeted [64Cu]-labeled PET radiotracerDrug
Single intravenous administration of a Granzyme-B targeted [64Cu]-labeled positron emission tomography (PET) radiotracer to assess pharmacokinetics, biodistribution, and radiation dosimetry in adult healthy volunteers.
| Study group | Role | What they receive |
|---|---|---|
| [Cu-64]RTX-4001 | Experimental | Arm Description: Single IV administration of [Cu-64]RTX-4001, a Granzyme-B-targeted PET radiotracer, in healthy adult volunteers. Receives: Drug: Granzyme-B targeted [64Cu]-labeled PET radiotracer |
| [Cu-64]RTX-4002 | Experimental | Arm Description: Single IV administration of [Cu-64]RTX-4002, a Granzyme-B-targeted PET radiotracer, in healthy adult volunteers. Receives: Drug: Granzyme-B targeted [64Cu]-labeled PET radiotracer |
What is being measured
The primary outcome is the main question the study is designed to answer.
Determine the maximum concentration (Cmax) of radiation (Pharmacokinetics) in the blood after a single dose of the GzmB-Targeted [Cu-64]-labeled compound
Blood samples will be collected Pre-dose, immediately post-dose, 45 minutes, 1 \& 4 hours, \& 24 hours post dose. Radiation (PK) to be measured by gamma counter (KBq/mL).
Measured: 24 hour period post injection.
Determine the time to maximum concentration (Tmax) in the blood after a single dose of the GzmB-Targeted [Cu-64]-labeled compound
Blood samples will be collected Pre-dose, immediately post-dose, 45 minutes, 1 \& 4 hours, \& 24 hours post dose. Time to maximum concentration to be measured in hours (h).
Measured: 24 hour period post injection
Determine the area under the curve (AUC) in blood after a single injection of the GzmB-Targeted [Cu-64]-labeled compound
Blood samples will be collected Pre-dose, immediately post-dose, 45 minutes, 1 \& 4 hours, \& 24 hours post dose. AUC to be calculated by kilobecquerel x hours/milliliter (KBq x h/mL)
Measured: 24 hour period post injection.
Determine the elimination half-life in the blood post a single injection of the GzmB-Targeted [Cu-64]-labeled compound
Blood samples will be collected Pre-dose, immediately post-dose, 45 minutes, 1 \& 4 hours, \& 24 hours post dose. Elimination to be measured by time to half of the product being excreted from the blood (as measured by gamma counter) in hours (h)
Measured: 24 hour period post injection
Determine the clearance in the blood after single injection of the GzmB-Targeted [Cu-64]-labeled compound
Blood samples will be collected Pre-dose, immediately post-dose, 45 minutes, 1 \& 4 hours, \& 24 hours post dose. Clearance to be measured by milliliter/minute.
Measured: 24 hour period post injection
Determine the volume of distribution in the blood after a single injection of the GzmB-Targeted [Cu-64]-labeled compound
Blood samples will be collected Pre-dose, immediately post-dose, 45 minutes, 1 \& 4 hours, \& 24 hours post dose. Volume to be measured by Liter
Measured: 24 hour period post injection
Evaluate the organ distribution of radioactivity for a single dose of GzmB-targeted [Cu64]-labeled compound
Measuring the uptake in organs from a PET/CT. Imaging timepoints will be collected at 20 minutes post dose, 1 \& 4 hours and 24 hours post dose
Measured: 24 hour period post injection
Evaluate the safety profile for a single dose of the GzmB-Targeted [Cu-64]-labeled compound in adult healthy volunteers
Determine the incidence, and severity of Treatment Emergent Adverse Events (TEAEs including SAEs).
Measured: From injection to 8 days post injection
Secondary outcomes (5)
Evaluate the radiation absorbed dose estimates for organs for a single dose of the GzmB-Targeted [Cu-64]-labeled compound
Imaging timepoints will be collected at 20 minutes post dose, 1 \& 4 hours, and 24 hours post dose. PET/CT will be used to assess the whole body effective dose as measured by mGy/MBq.
Measured: 24 hour period post injection
Evaluate the whole body effective dose estimated for a single dose of the GzmB-Targeted [Cu-64]-labeled compound
Imaging timepoints will be collected at 20 minutes post dose, 1 \& 4 hours, and 24 hours post dose. PET/CT will be used to assess the whole body effective dose as measured by mSv/MBq.
Measured: 24 hour period post injection
Examine whole-body excretion of a single dose of the GzmB-Targeted [Cu-64] labeled compound
Urine samples will be evaluated for radioactivity levels of GzmB-Targeted [Cu-64]-labeled compound. Samples will be measured by gamma counter to evaluate the amount of radiation excreted in each interval Ae(t) (kBq)
Measured: Samples will be taken continuously starting immediately post-dose through 24 hours post injection
Determine the total cumulative excretion over time in the urine (mL/min) for the GzmB-Targeted [Cu-64]-labeled compound
Samples will be taken continuously starting immediately post-dose through 24 hours post injection. Includes all quantified radioactivity as measured by gamma counter in urine up to the least measured timepoint.
Measured: A 24 hour period post injection
Determine the renal clearance for the GzmB-Targeted [Cu-64]-labeled compound
Urine samples will be taken continuously starting immediately post-dose through 24 hours post injection. Renal clearance is the volume of urine entirely cleared of a substance by the kidneys over time L/h
Measured: 24 hour period post injection
Timeline
From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.
- First posted19 Aug 2026
- Study start8 Jul 2026
- Primary completionDec 2026 (estimated)
- Study completionDec 2026 (estimated)
Resources
- Official record on ClinicalTrials.govThe registry entry this page is built from, with its full change history.
- Other trials for Healthy VolunteerStudies 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
- Early Phase 1
- Primary purpose
- Diagnosis
- Allocation
- Non-randomised
- Intervention model
- Sequential
- Masking
- None (open label)
- Enrolment
- 12 participants (estimated)
Sponsor and investigators
- Lead sponsor
- Ratio Therapeutics, Inc.
- Sponsor type
- Industry (pharma, biotech, devices)
- Responsible party
- Sponsor
IDs, dates and publications
- ClinicalTrials.gov ID
- NCT07774650
- Sponsor's protocol ID
- RTX-4000-101
- Status last verified
- Aug 2026
- First submitted
- 19 Mar 2026
- Last updated
- 1 Sep 2026
- Results posted
- No
- Data monitoring committee
- No
- FDA-regulated drug
- Yes
- FDA-regulated device
- No
- Individual data sharing
- No
Study at a glance
From the registry record, last updated by the sponsor on 1 Sep 2026. Recruitment status is as the sponsor reported it: confirm with the study team.
- Official title
- A Phase 0 Study of the Pharmacokinetics, Biodistribution and Radiation Dosimetry of Granzyme-B Targeted [Cu-64]-Labeled Positron Emission Tomography (PET) Radiotracers in Adult Healthy Volunteers
- ClinicalTrials.gov ID
- NCT07774650
- Acronym / sponsor ID
- RTX-4000-101
- Conditions
- Healthy Volunteer
- Phase
- Early Phase 1
- Study type
- Interventional
- Recruitment status
- Recruiting
- Enrolment
- 12 participants (estimated)
- Lead sponsor
- Ratio Therapeutics, Inc.Industry (pharma, biotech, devices)
- Study start
- 8 Jul 2026 (actual)
- Primary completion
- Dec 2026 (estimated)
- Study completion
- Dec 2026 (estimated)
- First posted
- 19 Aug 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.
This is an exploratory clinical study of copper-64 [Cu-64]-labeled granzyme B (GzmB)-targeted compounds for PET/CT imaging. The goal is to determine how GzmB-Targeted [Cu-64]-labeled compounds are distributed in the body by assessing PET/CT images and blood samples, and to assess the safety profile after a single intravenous dose.
Up to 6 healthy volunteers (3 female, 3 male) will receive one injection of a GzmB-targeted [Cu-64]-labeled compound, then undergo multiple whole-body PET/CT scans, blood and urine tests over about 24 hours, and a follow-up phone call around Day 7. Up to 2 GzmB-Targeted [Cu-64]-labeled compounds may be assessed (i.e. maximum of 12 healthy volunteers in total in the study).
Researchers will look at the blood activity of GzmB-Targeted [Cu-64]-labeled compound and the organ distribution and movement of the product in the body. They will also evaluate any changes in physical examination assessments, vital signs, ECG, and clinical laboratory measurements from pre-administration to post-administration.
Detailed description
Granzyme B (GzmB) is a cytotoxic serine protease released by activated T cells and natural killer cells, and its release acts as a functional marker of immune engagement. GzmB-Targeted [Cu-64]-labeled compounds are being developed as PET/CT tracers to image immune activation and inflammation. This first-in-human Phase 0 study in adult healthy volunteers is designed to characterize the pharmacokinetics, biodistribution, radiation dosimetry, and safety of GzmB-targeted [Cu-64]-labeled compounds.
Up to 6 participants (3 female, 3 male) will receive a single dose of a GzmB-targeted [Cu-64]-labeled compound, followed by serial whole-body PET/CT imaging, blood and urine sampling for pharmacokinetics and excretion, and safety assessments over approximately 24 hours post-dose, with a telephone follow-up at about 7 days. Up to 2 GzmB-Targeted [Cu-64]-labeled compounds may be assessed in the clinical trial (i.e. a maximum of 12 healthy volunteers in total in the study).
Data from this study will support lead candidate selection and inform further clinical development of a [Cu-64]-labeled GzmB-targeted imaging agent.
Study design
- Primary purpose
- Diagnosis
- Allocation
- Non-randomised
- Intervention model
- Sequential
- Masking
- None (open label)
- Number of arms
- 2
| Arm | Type | Receives |
|---|---|---|
| [Cu-64]RTX-4001 | Experimental | Drug: Granzyme-B targeted [64Cu]-labeled PET radiotracerArm Description: Single IV administration of [Cu-64]RTX-4001, a Granzyme-B-targeted PET radiotracer, in healthy adult volunteers. |
| [Cu-64]RTX-4002 | Experimental | Drug: Granzyme-B targeted [64Cu]-labeled PET radiotracerArm Description: Single IV administration of [Cu-64]RTX-4002, a Granzyme-B-targeted PET radiotracer, in healthy adult volunteers. |
Who may qualify
- Ages
- 18 to 60 years
- Sex
- All
- Healthy volunteers
- Accepted
- Age groups
- Adult
Key inclusion criteria (4 listed)
- Adult male or female participants 18-60 years of age judged to be in good health by the Investigator
- No clinically significant laboratory abnormalities; all tests of liver and kidney function within normal limits
- Capable of giving signed informed consent, which includes compliance with requirements and restrictions listed in the ICF and this protocol
- Female participants of childbearing potential and male participants who are fertile and have female partners of childbearing potential must agree to use adequate birth control throughout the study to the conclusion of follow-up.
Key exclusion criteria (11 listed)
- Pregnant or breast-feeding female participants (female participants of childbearing potential must have negative pregnancy tests at Screening and pre-dose Day 0)
- Inadequate venous access (at least two distinct access sites allowing for separate test agent administration and PK blood sampling are required)
- Inability or unwillingness to undergo serial PET/CT imaging
- Active infection or malignancy
- Known or suspected inflammatory, autoimmune or fibrotic disease
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 |
|---|---|---|
| Granzyme-B targeted [64Cu]-labeled PET radiotracerSingle intravenous administration of a Granzyme-B targeted [64Cu]-labeled positron emission tomography (PET) radiotracer to assess pharmacokinetics, biodistribution, and radiation dosimetry in adult healthy volunteers. | Drug | [Cu-64]RTX-4001, [Cu-64]RTX-4002 |
Primary outcome
Determine the maximum concentration (Cmax) of radiation (Pharmacokinetics) in the blood after a single dose of the GzmB-Targeted [Cu-64]-labeled compound
Time frame: 24 hour period post injection.
Blood samples will be collected Pre-dose, immediately post-dose, 45 minutes, 1 \& 4 hours, \& 24 hours post dose. Radiation (PK) to be measured by gamma counter (KBq/mL).
Determine the time to maximum concentration (Tmax) in the blood after a single dose of the GzmB-Targeted [Cu-64]-labeled compound
Time frame: 24 hour period post injection
Blood samples will be collected Pre-dose, immediately post-dose, 45 minutes, 1 \& 4 hours, \& 24 hours post dose. Time to maximum concentration to be measured in hours (h).
Determine the area under the curve (AUC) in blood after a single injection of the GzmB-Targeted [Cu-64]-labeled compound
Time frame: 24 hour period post injection.
Blood samples will be collected Pre-dose, immediately post-dose, 45 minutes, 1 \& 4 hours, \& 24 hours post dose. AUC to be calculated by kilobecquerel x hours/milliliter (KBq x h/mL)
Determine the elimination half-life in the blood post a single injection of the GzmB-Targeted [Cu-64]-labeled compound
Time frame: 24 hour period post injection
Blood samples will be collected Pre-dose, immediately post-dose, 45 minutes, 1 \& 4 hours, \& 24 hours post dose. Elimination to be measured by time to half of the product being excreted from the blood (as measured by gamma counter) in hours (h)
Determine the clearance in the blood after single injection of the GzmB-Targeted [Cu-64]-labeled compound
Time frame: 24 hour period post injection
Blood samples will be collected Pre-dose, immediately post-dose, 45 minutes, 1 \& 4 hours, \& 24 hours post dose. Clearance to be measured by milliliter/minute.
Determine the volume of distribution in the blood after a single injection of the GzmB-Targeted [Cu-64]-labeled compound
Time frame: 24 hour period post injection
Blood samples will be collected Pre-dose, immediately post-dose, 45 minutes, 1 \& 4 hours, \& 24 hours post dose. Volume to be measured by Liter
Evaluate the organ distribution of radioactivity for a single dose of GzmB-targeted [Cu64]-labeled compound
Time frame: 24 hour period post injection
Measuring the uptake in organs from a PET/CT. Imaging timepoints will be collected at 20 minutes post dose, 1 \& 4 hours and 24 hours post dose
Evaluate the safety profile for a single dose of the GzmB-Targeted [Cu-64]-labeled compound in adult healthy volunteers
Time frame: From injection to 8 days post injection
Determine the incidence, and severity of Treatment Emergent Adverse Events (TEAEs including SAEs).
5 secondary outcomes
Evaluate the radiation absorbed dose estimates for organs for a single dose of the GzmB-Targeted [Cu-64]-labeled compound
Time frame: 24 hour period post injection
Evaluate the whole body effective dose estimated for a single dose of the GzmB-Targeted [Cu-64]-labeled compound
Time frame: 24 hour period post injection
Examine whole-body excretion of a single dose of the GzmB-Targeted [Cu-64] labeled compound
Time frame: Samples will be taken continuously starting immediately post-dose through 24 hours post injection
Determine the total cumulative excretion over time in the urine (mL/min) for the GzmB-Targeted [Cu-64]-labeled compound
Time frame: A 24 hour period post injection
Determine the renal clearance for the GzmB-Targeted [Cu-64]-labeled compound
Time frame: 24 hour period post injection
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 Sep 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.
1 site in 1 country: see every site and its status.
Questions about this trial
What is this clinical trial studying?
A Early Phase 1 study testing Granzyme-B targeted [64Cu]-labeled PET radiotracer in people with Healthy Volunteer, run by Ratio Therapeutics, Inc. at 1 site in United States.
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 4 inclusion and 11 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: looking for participants now, as of the sponsor's last update on 1 Sep 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 States. 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.
What does this phase mean?
Early Phase 1 (sometimes called Phase 0) studies give a very small amount of a treatment to a few people, mainly to see how the body handles it.
Not every study follows the same path, and some studies (observational studies, device studies) have no phase.
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?
Contact Anna Carberry (203-444-6025, clinicrecruitment@indd.org), or a site near the patient. AzTrials does not enrol participants or take referrals.
What does the primary outcome measure?
Determine the maximum concentration (Cmax) of radiation (Pharmacokinetics) in the blood after a single dose of the GzmB-Targeted [Cu-64]-labeled compound (time frame: 24 hour period post injection.). The study lists 8 primary outcomes in all. 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 Sep 2026.