Healthy AdultsPhase 1NCT06837259
A Study to Learn if Study Medicines Called Cyclosporine and Clarithromycin Affect How the Body Processes the Other Study Medicine Called PF-07328948 in Healthy Adults
A Phase 1 study testing PF-07328948, cyclosporine and clarithromycin in people with Healthy Adults, run by Pfizer at 1 site in Belgium.
Trial summary
The purpose of this study is to learn about the effect of cyclosporine, an immunosuppressant (medicine that suppresses the immune system), on the pharmacokinetics (PK) of PF-07328948 in healthy participants (Part A). Read more about this study
- Who is it for?
- Ages 18 years and olderHealthy volunteers can take part
- Conditions the study is for
- Healthy Adults
- What is being tested?
- PF-07328948, cyclosporine and clarithromycin
- Type of treatment
- Pill or oral medicine
- Could I receive a placebo?
- No, everyone receives an active treatment
- How many people
- 26 participants
- Where
- 1 siteBelgium
- Study dates
- 19 Mar 2025to 11 Jun 2025
- Phase
- Phase 1
- 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
- Males and females (of non-childbearing potential) who are overtly healthy.
- Body mass index of 18.5-35 kg/m2; and a total body weight >50 kg (110 lb).
Who cannot join
- Evidence or history of clinically significant hematological, renal, endocrine, pulmonary, gastrointestinal, cardiovascular, hepatic, psychiatric, neurological, or allergic disease (including drug allergies, but excluding untreated, asymptomatic, seasonal allergies at the time of dosing).
- Any medical or psychiatric condition including recent (within the past year) or active suicidal ideation/behavior or laboratory abnormality or other conditions that may increase the risk of study participation or, in the investigator's judgment, make the participant inappropriate for the study.
- Screening supine blood pressure (BP) ≥140 mm Hg (systolic) or ≥90 mm Hg (diastolic) for participants <60 years; and ≥150/90 mm/Hg for participants ≥60 years old, following at least 5 minutes of supine rest. If systolic BP is ≥ 140 or 150 mm Hg (based on age) or diastolic ≥90 mm Hg, the BP should be repeated 2 more times and the average of the 3 BP values should be used to determine the participant's eligibility.
- Evidence of a prothrombotic state (history of deep vein thrombosis, pulmonary embolism, or arterial thrombosis or a known genetic predisposition [Factor V Leiden, prothrombin G20210A, Protein C/S deficiency, antithrombin deficiency])
- An eGFR <60 units mL/min/1.73m², as determined by the CKD-EPI equation using serum creatinine
- Standard 12 lead ECG that demonstrates clinically relevant abnormalities that may affect participant safety or interpretation of study results (eg, QTcF >450 ms, complete left bundle branch block (LBBB), signs of an acute or indeterminate age myocardial infarction, ST segment and/or T wave changes suggestive of myocardial ischemia, second or third degree AV block, or serious bradyarrhythmias or tachyarrhythmias).
- Participants with ANY of the following abnormalities in clinical laboratory tests at screening, as assessed by the study-specific laboratory and confirmed by a single repeat test, if deemed necessary: ALT, AST, Bilirubin ≥1.5 x ULN.
Trial locations and contacts
1 site in 1 country.
Belgium1 site
Pfizer Clinical Research Unit - Brussels
Brussels, Bruxelles-capitale, Région de, B-1070
About this study
Official title: A Phase 1, Open-Label, Fixed-Sequence Study to Evaluate the Effect of OATP Inhibition on the Single Dose Pharmacokinetics of PF-07328948 in Healthy Adult Participants.
The purpose of this study is to learn about the effect of cyclosporine, an immunosuppressant (medicine that suppresses the immune system), on the pharmacokinetics (PK) of PF-07328948 in healthy participants (Part A). The study may also estimate the effect of clarithromycin, an antibiotic, on the PK of PF-07328948 in healthy participants (Part B is optional).
This study is seeking participants who:
Read more
- are 18 years of age or older
- are male or female who are not of childbearing potential
- are healthy (do not have a disease) The study will consist of two parts - Part A and Part B.
Part A will consist of two treatments:
- one dose of PF-07328948 solution to be taken by mouth on day 1.
- one cyclosporine 600 mg capsule taken together with a dose of PF-07328948 solution by mouth on day 12.
Before study Part A starts, all participants will go through a screening process which may last for a period of up to 28 days. During this period, the participant's medical history and past and current medications will be reviewed. A series of tests will also be performed.
If the participants meet all required criteria and want to continue, they will be brought into the study clinic to stay overnight for 17 days. During this period, the experiences of participants receiving the study medicine will be examined. Samples for laboratory assessments will be collected. Vital signs and medical assessments will also be performed. This will help determine if it is safe to take the study medicines together and what happens to these medicines in one's body (called PK assessment). After Part A, participants will be discharged from the clinic.
Based upon the results of Part A, study participants may proceed to Part B. If Part B occurs, participants will return to the study clinic and remain in the clinic for 8 days. There will be a gap of at least 7 days between Part A and Part B.
Part B will consist of a third treatment:
- clarithromycin 500 mg tablet to be taken 2 times a day for 6 days. On day 4, the tablet will be taken together by mouth with a dose of PF-07328948 solution.
During this period, similar laboratory and medical assessments as done in Part A will occur. After Part B, participants will be discharged from the clinic.
The participant will be contacted for a follow up visit by telephone about 30 days after final treatment. This is to check up on how the participant is doing and to conclude the study. If only Part A occurs, a participant will be in the study about 44 days. If Part B occurs, a participant will be in the study for about 64 days.
- Conditions
- Healthy Adults
- Being tested
- PF-07328948, cyclosporine, clarithromycin
What participants receive
What participants receive. In a randomised study each person is assigned to one group by chance.
PF-07328948Drug
single oral dose day 1 and day 12 (Part A) and day 4 (part B)
cyclosporineDrug
600 mg capsule day 12 (Part A)
clarithromycinDrug
500 mg tablets twice daily day 1 to day 6 (Part B)
| Study group | Role | What they receive |
|---|---|---|
| Period 1 | Experimental | PF-07328948 Receives: Drug: PF-07328948 |
| Period 2 | Experimental | cyclosporine and PF-07328948 Receives: Drug: PF-07328948; Drug: cyclosporine |
| Period 3 (optional) | Experimental | clarithromycin and PF-07328948 Receives: Drug: PF-07328948; Drug: clarithromycin |
What is being measured
The primary outcome is the main question the study is designed to answer.
Maximum Observed Plasma Concentration (Cmax) of PF-07328948
Measured: Hour 0, 1, 2, 3, 4, 6, 8, 10, 12, 24, 36, 48, 72 post-dose
Area Under the Curve From Time Zero to Extrapolated Infinite Time (AUCinf) of PF-07328948
if data permits
Measured: Hour 0, 1, 2, 3, 4, 6, 8, 10, 12, 24, 36, 48, 72 post-dose
Area under the plasma concentration-time curve from time 0 to the time of the last quantifiable concentration (AUClast) of PF-07328948
If AUCinf cannot be completed
Measured: Hour 0, 1, 2, 3, 4, 6, 8, 10, 12, 24, 36, 48, 72 post-dose
Secondary outcomes (4)
Number of Participants With Treatment Emergent Treatment-Related Adverse Events (AEs)
Measured: Baseline (Day 0) up to 35 days after last dose of study medication
Number of Participants With Clinically Significant Change From Baseline in Laboratory Abnormalities
Measured: Baseline up to Day 18 (Part A) or up to Day 35 (optional Part B)
Number of Participants With Clinically Significant Change From Baseline in Blood Pressure and Pulse Rate
Measured: Baseline up to Day 18 (Part A) or up to Day 35 (optional Part B)
Number of Participants With Clinically Significant Change in Electrocardiogram (ECG) Findings
Measured: Baseline up to Day 18 (Part A) or up to Day 35 (optional Part B)
Timeline
From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.
- First posted20 Feb 2025
- Study start19 Mar 2025
- Primary completion11 Jun 2025
- Study completion11 Jun 2025
Resources
- Official record on ClinicalTrials.govThe registry entry this page is built from, with its full change history.
- Other trials for Healthy AdultsStudies 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
- Sequential
- Masking
- None (open label)
- Enrolment
- 26 participants (actual)
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
- NCT06837259
- Sponsor's protocol ID
- C4921008
- Other IDs
- 2024-520126-11-00
- Status last verified
- Jan 2026
- First submitted
- 14 Feb 2025
- Last updated
- 2 Feb 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 2 Feb 2026. Recruitment status is as the sponsor reported it: confirm with the study team.
- Official title
- A Phase 1, Open-Label, Fixed-Sequence Study to Evaluate the Effect of OATP Inhibition on the Single Dose Pharmacokinetics of PF-07328948 in Healthy Adult Participants.
- ClinicalTrials.gov ID
- NCT06837259
- Acronym / sponsor ID
- C4921008
- Conditions
- Healthy Adults
- Phase
- Phase 1
- Study type
- Interventional
- Recruitment status
- Completed
- Enrolment
- 26 participants (actual)
- Lead sponsor
- PfizerIndustry (pharma, biotech, devices)
- Study start
- 19 Mar 2025 (actual)
- Primary completion
- 11 Jun 2025 (actual)
- Study completion
- 11 Jun 2025 (actual)
- First posted
- 20 Feb 2025 (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 learn about the effect of cyclosporine, an immunosuppressant (medicine that suppresses the immune system), on the pharmacokinetics (PK) of PF-07328948 in healthy participants (Part A). The study may also estimate the effect of clarithromycin, an antibiotic, on the PK of PF-07328948 in healthy participants (Part B is optional).
This study is seeking participants who:
- are 18 years of age or older
- are male or female who are not of childbearing potential
- are healthy (do not have a disease) The study will consist of two parts - Part A and Part B.
Part A will consist of two treatments:
- one dose of PF-07328948 solution to be taken by mouth on day 1.
- one cyclosporine 600 mg capsule taken together with a dose of PF-07328948 solution by mouth on day 12.
Before study Part A starts, all participants will go through a screening process which may last for a period of up to 28 days. During this period, the participant's medical history and past and current medications will be reviewed. A series of tests will also be performed.
If the participants meet all required criteria and want to continue, they will be brought into the study clinic to stay overnight for 17 days. During this period, the experiences of participants receiving the study medicine will be examined. Samples for laboratory assessments will be collected. Vital signs and medical assessments will also be performed. This will help determine if it is safe to take the study medicines together and what happens to these medicines in one's body (called PK assessment). After Part A, participants will be discharged from the clinic.
Based upon the results of Part A, study participants may proceed to Part B. If Part B occurs, participants will return to the study clinic and remain in the clinic for 8 days. There will be a gap of at least 7 days between Part A and Part B.
Part B will consist of a third treatment:
- clarithromycin 500 mg tablet to be taken 2 times a day for 6 days. On day 4, the tablet will be taken together by mouth with a dose of PF-07328948 solution.
During this period, similar laboratory and medical assessments as done in Part A will occur. After Part B, participants will be discharged from the clinic.
The participant will be contacted for a follow up visit by telephone about 30 days after final treatment. This is to check up on how the participant is doing and to conclude the study. If only Part A occurs, a participant will be in the study about 44 days. If Part B occurs, a participant will be in the study for about 64 days.
Study design
- Primary purpose
- Basic science
- Allocation
- Randomised
- Intervention model
- Sequential
- Masking
- None (open label)
- Number of arms
- 3
| Arm | Type | Receives |
|---|---|---|
| Period 1 | Experimental | Drug: PF-07328948PF-07328948 |
| Period 2 | Experimental | Drug: PF-07328948, Drug: cyclosporinecyclosporine and PF-07328948 |
| Period 3 (optional) | Experimental | Drug: PF-07328948, Drug: clarithromycinclarithromycin and PF-07328948 |
Who may qualify
- Ages
- 18 years and older
- Sex
- All
- Healthy volunteers
- Accepted
- Age groups
- Adult, Older adult
Key inclusion criteria (2 listed)
- Males and females (of non-childbearing potential) who are overtly healthy.
- Body mass index of 18.5-35 kg/m2; and a total body weight >50 kg (110 lb).
Key exclusion criteria (7 listed)
- Evidence or history of clinically significant hematological, renal, endocrine, pulmonary, gastrointestinal, cardiovascular, hepatic, psychiatric, neurological, or allergic disease (including drug allergies, but excluding untreated, asymptomatic, seasonal allergies at the time of dosing).
- Any medical or psychiatric condition including recent (within the past year) or active suicidal ideation/behavior or laboratory abnormality or other conditions that may increase the risk of study participation or, in the investigator's judgment, make the participant inappropriate for the study.
- Screening supine blood pressure (BP) ≥140 mm Hg (systolic) or ≥90 mm Hg (diastolic) for participants <60 years; and ≥150/90 mm/Hg for participants ≥60 years old, following at least 5 minutes of supine rest. If systolic BP is ≥ 140 or 150 mm Hg (based on age) or diastolic ≥90 mm Hg, the BP should be repeated 2 more times and the average of the 3 BP values should be used to determine the participant's eligibility.
- Evidence of a prothrombotic state (history of deep vein thrombosis, pulmonary embolism, or arterial thrombosis or a known genetic predisposition [Factor V Leiden, prothrombin G20210A, Protein C/S deficiency, antithrombin deficiency])
- An eGFR <60 units mL/min/1.73m², as determined by the CKD-EPI equation using serum creatinine
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 |
|---|---|---|
| PF-07328948single oral dose day 1 and day 12 (Part A) and day 4 (part B) | Drug | Period 1, Period 2, Period 3 (optional) |
| cyclosporine600 mg capsule day 12 (Part A) | Drug | Period 2 |
| clarithromycin500 mg tablets twice daily day 1 to day 6 (Part B) | Drug | Period 3 (optional) |
Primary outcome
Maximum Observed Plasma Concentration (Cmax) of PF-07328948
Time frame: Hour 0, 1, 2, 3, 4, 6, 8, 10, 12, 24, 36, 48, 72 post-dose
Area Under the Curve From Time Zero to Extrapolated Infinite Time (AUCinf) of PF-07328948
Time frame: Hour 0, 1, 2, 3, 4, 6, 8, 10, 12, 24, 36, 48, 72 post-dose
if data permits
Area under the plasma concentration-time curve from time 0 to the time of the last quantifiable concentration (AUClast) of PF-07328948
Time frame: Hour 0, 1, 2, 3, 4, 6, 8, 10, 12, 24, 36, 48, 72 post-dose
If AUCinf cannot be completed
4 secondary outcomes
Number of Participants With Treatment Emergent Treatment-Related Adverse Events (AEs)
Time frame: Baseline (Day 0) up to 35 days after last dose of study medication
Number of Participants With Clinically Significant Change From Baseline in Laboratory Abnormalities
Time frame: Baseline up to Day 18 (Part A) or up to Day 35 (optional Part B)
Number of Participants With Clinically Significant Change From Baseline in Blood Pressure and Pulse Rate
Time frame: Baseline up to Day 18 (Part A) or up to Day 35 (optional Part B)
Number of Participants With Clinically Significant Change in Electrocardiogram (ECG) Findings
Time frame: Baseline up to Day 18 (Part A) or up to Day 35 (optional Part B)
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 2 Feb 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. This study is not recruiting at the moment.
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 PF-07328948, cyclosporine and clarithromycin in people with Healthy Adults, 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 7 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 2 Feb 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?
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?
Maximum Observed Plasma Concentration (Cmax) of PF-07328948 (time frame: Hour 0, 1, 2, 3, 4, 6, 8, 10, 12, 24, 36, 48, 72 post-dose). The study lists 3 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 2 Feb 2026.