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, 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:

• 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 Overview

• Status: Completed
• Conditions: Healthy Adults
• Intervention / Treatment: Drug: cyclosporine; Drug: clarithromycin; Drug: PF-07328948

• Study Type: Interventional
• Enrollment (Actual): 26
• Phase: Phase 1

Contacts and Locations

Study Locations

• Belgium
  • Bruxelles-capitale, Région de
    • Brussels, Bruxelles-capitale, Région de, Belgium, B-1070
      • Pfizer Clinical Research Unit - Brussels

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: Adult; Older Adult
• Accepts Healthy Volunteers: Yes

Description

Inclusion:

• 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).

Exclusion:

• 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.

Study Plan

How is the study designed?

Design Details

• Primary Purpose: Basic Science
• Allocation: Randomized
• Interventional Model: Sequential Assignment
• Masking: None (Open Label)

Number of Arms

3

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
Experimental: Period 1; PF-07328948	Drug: PF-07328948; single oral dose day 1 and day 12 (Part A) and day 4 (part B)
Experimental: Period 2; cyclosporine and PF-07328948	Drug: cyclosporine; 600 mg capsule day 12 (Part A); Drug: PF-07328948; single oral dose day 1 and day 12 (Part A) and day 4 (part B)
Experimental: Period 3 (optional); clarithromycin and PF-07328948	Drug: clarithromycin; 500 mg tablets twice daily day 1 to day 6 (Part B); Drug: PF-07328948; single oral dose day 1 and day 12 (Part A) and day 4 (part B)

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Maximum Observed Plasma Concentration (Cmax) of PF-07328948		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	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	Hour 0, 1, 2, 3, 4, 6, 8, 10, 12, 24, 36, 48, 72 post-dose

Secondary Outcome Measures

Outcome Measure	Time Frame
Number of Participants With Treatment Emergent Treatment-Related Adverse Events (AEs)	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	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	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	Baseline up to Day 18 (Part A) or up to Day 35 (optional Part B)

Collaborators and Investigators

• Sponsor: Pfizer
• Investigators: Study Director: Pfizer CT.gov Call Center, Pfizer

Publications and helpful links

Helpful Links

• To obtain contact information for a study center near you, click here.

Study record dates

Study Major Dates

• Study Start (Actual): March 19, 2025
• Primary Completion (Actual): June 11, 2025
• Study Completion (Actual): June 11, 2025

Study Registration Dates

• First Submitted: February 14, 2025
• First Submitted That Met QC Criteria: February 14, 2025
• First Posted (Actual): February 20, 2025

Study Record Updates

• Last Update Posted (Actual): February 2, 2026
• Last Update Submitted That Met QC Criteria: January 29, 2026
• Last Verified: January 1, 2026

More Information

Terms related to this study

• Additional Relevant MeSH Terms: Peptides; Amino Acids, Peptides, and Proteins; Organic Chemicals; Polycyclic Compounds; Macrolides; Lactones; Macrocyclic Compounds; Peptides, Cyclic; Cyclosporins; Erythromycin; Polyketides; Cyclosporine; Clarithromycin
• Other Study ID Numbers: C4921008; 2024-520126-11-00 (Registry Identifier: CTIS (EU))

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: NO
• IPD Plan Description: 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.

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: Yes
• Studies a U.S. FDA-regulated device product: No
• product manufactured in and exported from the U.S.: No