Healthy ParticipantPhase 1NCT07721402
A Study to Learn About How Different Forms of Study Medicine Prifetrastat Are Taken Up Into the Blood in Healthy Adults
A Phase 1 study testing prifetrastat Reference, prifetrastat Test 1 and prifetrastat Test 2 in people with Healthy Participant, run by Pfizer at 1 site in Belgium.
Trial summary
The purpose of this study is to understand the relative amount of drug that enters bloodstream from prifetrastat product lots differing in active ingredient particle size distribution. Read more about this study
- Who is it for?
- Ages 18 years and olderHealthy volunteers can take part
- Conditions the study is for
- Healthy Participant
- What is being tested?
- prifetrastat Reference, prifetrastat Test 1 and prifetrastat Test 2
- Could I receive a placebo?
- No, everyone receives an active treatment
- How many people
- 32 participants
- Where
- 1 siteBelgium
- Study dates
- 14 Jul 2026to 8 Dec 2026
- Phase
- 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 years and older
- All sexes
- Healthy volunteers accepted
- Adult, Older adult
Who may be able to join
- Females of non-childbearing potential and males >=18 years of age at screening who are overtly healthy as determined by medical evaluation including medical history, physical examination, laboratory tests, vital signs and 12-lead ECGs.
- BMI of 18-32 kilogram per meter square(Kg/m^2); and a total body weight >50 kg (110 lb).
Who cannot join
- Use of prescription or nonprescription drugs and dietary and herbal supplements within 14 days or 5 half-lives (whichever is longer) prior to the first dose of study intervention
- Prior use of epigenetic modifying agents. Participants will only be permitted to enroll in a single arm of this study (cannot participate in Arm 1 and Arm 2).
- Current use of any prohibited concomitant medication(s) or unwillingness or inability to use a required concomitant medication(s).
- current use or anticipated need for food or drugs that are known strong inducers or inhibitors of CYP2C9 or CYP3A4, including their administration within 14 days plus 5 half-lives of the strong inducers or inhibitors of CYP2C9 or CYP3A4, whichever is longer, prior to first dose of study intervention, during the treatment period, and within 2 days after the last dose of prifetrastat
- Proton pump inhibitors must be discontinued at least 14 days prior to the first dose of study medication and throughout treatment period.
Trial locations and contacts
1 site in 1 country. Contact the study team or a site near you to ask about taking part.
Belgium1 site, 1 recruiting
- Recruiting
Pfizer Clinical Research Unit - Brussels
Brussels, Bruxelles-capitale, Région de, B-1070
About this study
Official title: A PHASE 1, RANDOMIZED, OPEN-LABEL, 2-PERIOD, 4-SEQUENCE SINGLE-DOSE CROSSOVER STUDY IN HEALTHY PARTICIPANTS TO INVESTIGATE THE RELATIVE BIOAVAILABILITY OF PRIFETRISTAT DRUG PRODUCT DIFFERING IN PARTICLE SIZE DISTRIBUTION
The purpose of this study is to understand the relative amount of drug that enters bloodstream from prifetrastat product lots differing in active ingredient particle size distribution.
The study is seeking participants who are:
Read more
Healthy males and females of non-childbearing potential >=18 years of age at screening
Participants in the study will receive a single dose of prifetrastat by mouth. After at least 14 days, they will receive another dose of prifetrastat by mouth. Each dose received by the patient will be in tablet form. The sequence in which tablets are given will be random.
The study will help understand how the difference in particle size distributions of the tablets may, or may not, affect how the drug is absorbed, processed, and eliminated by the body.
Participants will remain in the study clinic for 21 days. However, they may be permitted to leave between periods, and will have one follow-up contact.
- Conditions
- Healthy Participant
- Being tested
- prifetrastat Reference, prifetrastat Test 1, prifetrastat Test 2
- Keywords
- Healthy Adults, Bioavailability, Pharmacokinetics, Absorption, Distribution, Metabolism, Elimination
What participants receive
What participants receive. In a randomised study each person is assigned to one group by chance.
prifetrastat ReferenceDrug
Reference Treatment
prifetrastat Test 1Drug
Test 1 Treatment
prifetrastat Test 2Drug
Test 2 Treatment
| Study group | Role | What they receive |
|---|---|---|
| Arm 1 prifetrastat | Active comparator | Crossover Receives: Drug: prifetrastat Reference; Drug: prifetrastat Test 1 |
| Arm 2 prifetrastat | Active comparator | Crossover Receives: Drug: prifetrastat Reference; Drug: prifetrastat Test 2 |
What is being measured
The primary outcome is the main question the study is designed to answer.
Area under the Plasma Concentration-Time profile from time 0 to extrapolated infinite time (AUCinf) of Reference treatment of prifetrastat (AUClast If data does not permit AUCinf)
AUCinf was area under the plasma concentration time-curve from zero (pre-dose) extrapolated out to infinite time (If data permits).
Measured: Pre-dose, 0, 0.5, 1, 1.5, 2, 3, 4 ,6 , 8, 12, 24, 36, 48, 72, 96, 144 hours post dose in period 1 and period 2
Maximum Observed Plasma Concentration (Cmax) profile of Reference prifetrastat treatment
Cmax was the maximum observed plasma concentration directly observed from data.
Measured: Pre-dose, 0, 0.5, 1, 1.5, 2, 3, 4 ,6 , 8, 12, 24, 36, 48, 72, 96, 144 hours post dose in period 1 and period 2
Area under the Plasma Concentration-Time profile from time 0 to extrapolated infinite time (AUCinf) of Test 1 treatment of prifetrastat (AUClast If data does not permit AUCinf)
AUCinf was area under the plasma concentration time-curve from zero (pre-dose) extrapolated out to infinite time (If data permits).
Measured: Pre-dose, 0, 0.5, 1, 1.5, 2, 3, 4 ,6 , 8, 12, 24, 36, 48, 72, 96, 144 hours post dose in period 1 and period 2
Maximum Observed Plasma Concentration (Cmax) profile of Test 1 prifetrastat treatment
Cmax was the maximum observed plasma concentration directly observed from data.
Measured: Pre-dose, 0, 0.5, 1, 1.5, 2, 3, 4 ,6 , 8, 12, 24, 36, 48, 72, 96, 144 hours post dose in period 1 and period 2
Area under the Plasma Concentration-Time profile from time 0 to extrapolated infinite time (AUCinf) of Test 2 treatment of prifetrastat (AUClast If data does not permit AUCinf)
AUCinf was area under the plasma concentration time-curve from zero (pre-dose) extrapolated out to infinite time (If data permits).
Measured: Pre-dose, 0, 0.5, 1, 1.5, 2, 3, 4 ,6 , 8, 12, 24, 36, 48, 72, 96, 144 hours post dose in period 1 and period 2
Maximum Observed Plasma Concentration (Cmax) profile of Test 2 prifetrastat treatment
Cmax was the maximum observed plasma concentration directly observed from data.
Measured: Pre-dose, 0, 0.5, 1, 1.5, 2, 3, 4 ,6 , 8, 12, 24, 36, 48, 72, 96, 144 hours post dose in period 1 and period 2
Secondary outcomes (5)
Number of Participants With Treatment Emergent Adverse Events (TEAEs)
Measured: Up to Day 35 after the last dose of study intervention in Period 2
Number of Participants with Clinically Significant Abnormalities in Laboratory Parameters
Measured: Up to Day 35 after the last dose of study intervention in Period 2
Number of Participants With Clinically Significant Abnormalities in Vital Signs
Measured: Up to Day 35 after the last dose of study intervention in Period 2
Number of Participants With Clinically Significant Electrocardiogram (ECG) Abnormalities
Measured: Up to Day 35 after the last dose of study intervention in Period 2
Number of Participants With Clinically Significant Physical Examination Abnormalities
Measured: Up to Day 35 after the last dose of study intervention in Period 2
Timeline
From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.
- First posted23 Jul 2026
- Study start14 Jul 2026
- Primary completion8 Dec 2026 (estimated)
- Study completion8 Dec 2026 (estimated)
Resources
- Official record on ClinicalTrials.govThe registry entry this page is built from, with its full change history.
- Other trials for Healthy ParticipantStudies of the same condition, open and under way.
- More trials run by PfizerThe 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 1
- Primary purpose
- Basic science
- Allocation
- Randomised
- Intervention model
- Crossover
- Masking
- None (open label)
- Enrolment
- 32 participants (estimated)
Sponsor and investigators
- Lead sponsor
- Pfizer
- Sponsor type
- Industry (pharma, biotech, devices)
- Responsible party
- Sponsor
- Investigators
- Pfizer CT.gov Call Center, Study director, Pfizer
IDs, dates and publications
- ClinicalTrials.gov ID
- NCT07721402
- Sponsor's protocol ID
- C4551017
- Other IDs
- 2026-526038-26-00
- Status last verified
- Jul 2026
- First submitted
- 16 Jul 2026
- Last updated
- 23 Jul 2026
- Results posted
- No
- Data monitoring committee
- No
- FDA-regulated drug
- Yes
- FDA-regulated device
- No
- Individual data sharing
- No: Pfizer will provide access to individual de-identified participant data and related study documents (e.g. protocol, Statistical Analysis Plan (SAP), Clinical Study Report (CSR)) upon request from qualified researchers, and subject to certain criteria, conditions, and exceptions. Further details on Pfizer's data sharing criteria and process for requesting access can be found at: https://www.pfizer.com/science/clinical\_trials/trial\_data\_and\_results/data\_requests.
Study at a glance
From the registry record, last updated by the sponsor on 23 Jul 2026. Recruitment status is as the sponsor reported it: confirm with the study team.
- Official title
- A PHASE 1, RANDOMIZED, OPEN-LABEL, 2-PERIOD, 4-SEQUENCE SINGLE-DOSE CROSSOVER STUDY IN HEALTHY PARTICIPANTS TO INVESTIGATE THE RELATIVE BIOAVAILABILITY OF PRIFETRISTAT DRUG PRODUCT DIFFERING IN PARTICLE SIZE DISTRIBUTION
- ClinicalTrials.gov ID
- NCT07721402
- Acronym / sponsor ID
- C4551017
- Conditions
- Healthy Participant
- Keywords
- Healthy Adults, Bioavailability, Pharmacokinetics, Absorption, Distribution, Metabolism, Elimination
- Phase
- Phase 1
- Study type
- Interventional
- Recruitment status
- Recruiting
- Enrolment
- 32 participants (estimated)
- Lead sponsor
- PfizerIndustry (pharma, biotech, devices)
- Study start
- 14 Jul 2026 (actual)
- Primary completion
- 8 Dec 2026 (estimated)
- Study completion
- 8 Dec 2026 (estimated)
- First posted
- 23 Jul 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 purpose of this study is to understand the relative amount of drug that enters bloodstream from prifetrastat product lots differing in active ingredient particle size distribution.
The study is seeking participants who are:
Healthy males and females of non-childbearing potential >=18 years of age at screening
Participants in the study will receive a single dose of prifetrastat by mouth. After at least 14 days, they will receive another dose of prifetrastat by mouth. Each dose received by the patient will be in tablet form. The sequence in which tablets are given will be random.
The study will help understand how the difference in particle size distributions of the tablets may, or may not, affect how the drug is absorbed, processed, and eliminated by the body.
Participants will remain in the study clinic for 21 days. However, they may be permitted to leave between periods, and will have one follow-up contact.
Study design
- Primary purpose
- Basic science
- Allocation
- Randomised
- Intervention model
- Crossover
- Masking
- None (open label)
- Number of arms
- 2
| Arm | Type | Receives |
|---|---|---|
| Arm 1 prifetrastat | Active comparator | Drug: prifetrastat Reference, Drug: prifetrastat Test 1Crossover |
| Arm 2 prifetrastat | Active comparator | Drug: prifetrastat Reference, Drug: prifetrastat Test 2Crossover |
Who may qualify
- Ages
- 18 years and older
- Sex
- All
- Healthy volunteers
- Accepted
- Age groups
- Adult, Older adult
Key inclusion criteria (2 listed)
- Females of non-childbearing potential and males >=18 years of age at screening who are overtly healthy as determined by medical evaluation including medical history, physical examination, laboratory tests, vital signs and 12-lead ECGs.
- BMI of 18-32 kilogram per meter square(Kg/m^2); and a total body weight >50 kg (110 lb).
Key exclusion criteria (5 listed)
- Use of prescription or nonprescription drugs and dietary and herbal supplements within 14 days or 5 half-lives (whichever is longer) prior to the first dose of study intervention
- Prior use of epigenetic modifying agents. Participants will only be permitted to enroll in a single arm of this study (cannot participate in Arm 1 and Arm 2).
- Current use of any prohibited concomitant medication(s) or unwillingness or inability to use a required concomitant medication(s).
- current use or anticipated need for food or drugs that are known strong inducers or inhibitors of CYP2C9 or CYP3A4, including their administration within 14 days plus 5 half-lives of the strong inducers or inhibitors of CYP2C9 or CYP3A4, whichever is longer, prior to first dose of study intervention, during the treatment period, and within 2 days after the last dose of prifetrastat
- Proton pump inhibitors must be discontinued at least 14 days prior to the first dose of study medication and throughout treatment period.
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 |
|---|---|---|
| prifetrastat ReferenceReference Treatment | Drug | Arm 1 prifetrastat, Arm 2 prifetrastat |
| prifetrastat Test 1Test 1 Treatment | Drug | Arm 1 prifetrastat |
| prifetrastat Test 2Test 2 Treatment | Drug | Arm 2 prifetrastat |
Primary outcome
Area under the Plasma Concentration-Time profile from time 0 to extrapolated infinite time (AUCinf) of Reference treatment of prifetrastat (AUClast If data does not permit AUCinf)
Time frame: Pre-dose, 0, 0.5, 1, 1.5, 2, 3, 4 ,6 , 8, 12, 24, 36, 48, 72, 96, 144 hours post dose in period 1 and period 2
AUCinf was area under the plasma concentration time-curve from zero (pre-dose) extrapolated out to infinite time (If data permits).
Maximum Observed Plasma Concentration (Cmax) profile of Reference prifetrastat treatment
Time frame: Pre-dose, 0, 0.5, 1, 1.5, 2, 3, 4 ,6 , 8, 12, 24, 36, 48, 72, 96, 144 hours post dose in period 1 and period 2
Cmax was the maximum observed plasma concentration directly observed from data.
Area under the Plasma Concentration-Time profile from time 0 to extrapolated infinite time (AUCinf) of Test 1 treatment of prifetrastat (AUClast If data does not permit AUCinf)
Time frame: Pre-dose, 0, 0.5, 1, 1.5, 2, 3, 4 ,6 , 8, 12, 24, 36, 48, 72, 96, 144 hours post dose in period 1 and period 2
AUCinf was area under the plasma concentration time-curve from zero (pre-dose) extrapolated out to infinite time (If data permits).
Maximum Observed Plasma Concentration (Cmax) profile of Test 1 prifetrastat treatment
Time frame: Pre-dose, 0, 0.5, 1, 1.5, 2, 3, 4 ,6 , 8, 12, 24, 36, 48, 72, 96, 144 hours post dose in period 1 and period 2
Cmax was the maximum observed plasma concentration directly observed from data.
Area under the Plasma Concentration-Time profile from time 0 to extrapolated infinite time (AUCinf) of Test 2 treatment of prifetrastat (AUClast If data does not permit AUCinf)
Time frame: Pre-dose, 0, 0.5, 1, 1.5, 2, 3, 4 ,6 , 8, 12, 24, 36, 48, 72, 96, 144 hours post dose in period 1 and period 2
AUCinf was area under the plasma concentration time-curve from zero (pre-dose) extrapolated out to infinite time (If data permits).
Maximum Observed Plasma Concentration (Cmax) profile of Test 2 prifetrastat treatment
Time frame: Pre-dose, 0, 0.5, 1, 1.5, 2, 3, 4 ,6 , 8, 12, 24, 36, 48, 72, 96, 144 hours post dose in period 1 and period 2
Cmax was the maximum observed plasma concentration directly observed from data.
5 secondary outcomes
Number of Participants With Treatment Emergent Adverse Events (TEAEs)
Time frame: Up to Day 35 after the last dose of study intervention in Period 2
Number of Participants with Clinically Significant Abnormalities in Laboratory Parameters
Time frame: Up to Day 35 after the last dose of study intervention in Period 2
Number of Participants With Clinically Significant Abnormalities in Vital Signs
Time frame: Up to Day 35 after the last dose of study intervention in Period 2
Number of Participants With Clinically Significant Electrocardiogram (ECG) Abnormalities
Time frame: Up to Day 35 after the last dose of study intervention in Period 2
Number of Participants With Clinically Significant Physical Examination Abnormalities
Time frame: Up to Day 35 after the last dose of study intervention in Period 2
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 23 Jul 2026.
- To obtain contact information for a study center near you, click here.Link provided by the sponsor.
- Individual participant dataSharing planned: No. Pfizer will provide access to individual de-identified participant data and related study documents (e.g. protocol, Statistical Analysis Plan (SAP), Clinical Study Report (CSR)) upon request from qualified researchers, and subject to certain criteria, conditions, and exceptions. Further details on Pfizer's data sharing criteria and process for requesting access can be found at: https://www.pfizer.com/science/clinical_trials/trial_data_and_results/data_requests.
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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.
Pfizer CT.gov Call Center study director
Pfizer
1 site in 1 country: see every site and its status.
Questions about this trial
What is this clinical trial studying?
A Phase 1 study testing prifetrastat Reference, prifetrastat Test 1 and prifetrastat Test 2 in people with Healthy Participant, run by Pfizer at 1 site in Belgium.
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 5 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 23 Jul 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 Belgium. 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?
Phase 1 studies test a treatment in a small group of people for the first time or in a new way, mainly to check safety and find the right dose.
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 Pfizer CT.gov Call Center (1-800-718-1021, ClinicalTrials.gov_Inquiries@pfizer.com), or a site near the patient. AzTrials does not enrol participants or take referrals.
What does the primary outcome measure?
Area under the Plasma Concentration-Time profile from time 0 to extrapolated infinite time (AUCinf) of Reference treatment of prifetrastat (AUClast If data does not permit AUCinf) (time frame: Pre-dose, 0, 0.5, 1, 1.5, 2, 3, 4 ,6 , 8, 12, 24, 36, 48, 72, 96, 144 hours post dose in period 1 and period 2). The study lists 6 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 23 Jul 2026.