A Study to Learn How Different Amounts of the Study Medicine Called PF-08103402 Are Tolerated and Act in the Body in Healthy Adults or Adults With Mild To-moderate Asthma

A PHASE 1 STUDY TO EVALUATE SAFETY, TOLERABILITY, PHARMACOKINETICS, PHARMACODYNAMICS, RELATIVE BIOAVAILABILITY, FOOD EFFECT, METABOLISM & EXCRETION, AND DRUG-DRUG INTERACTION POTENTIAL OF PF-08103402 IN HEALTHY ADULTS AND/OR ADULTS WITH MILD TO MODERATE ASTHMA

The purpose of this study is to learn about the safety of a new study medicine called PF-08103402 in healthy adults (do not have disease) and or in adults with mild-to-moderate asthma. This is the first time the study medicine is being given to people.

For Parts A, B, C, D and F, the study is seeking participants who:

• Are healthy (do not have disease) males or females who can no longer have children,
• Are 18 to 65 years old,
• Have a body mass index (BMI) of 16 to 32 kilograms per meter squared and a body weight of more than 50 kilograms (110 pounds). Body mass index is a way to measure body fat by using a person's height and weight

For Part A (optional group or cohort 3: Japanese participants only):

• A body weight of more than 45 kilograms (100 pounds).
• Have 4 biological Japanese grandparents who were born in Japan.

For Part E only:

• Adults with a documented history of asthma (confirmed by a doctor) for at least 12 months before entering the study.
• Have a body mass index (BMI) of 16 to 35 kilograms per meter squared and a total body weight of more than 50 kilograms (110 pounds).

The study has six parts: Part A, Part B, Part C, Part D, Part E and Part F. The study medicine will be taken as a suspension or tablet by mouth 1 time a day (except in Parts B and E where it will be taken 1 time a day for 14 days) at the study clinic. The study will help understand:

• how the body processes the study medicine in healthy participants (Parts A and B),
• how much of the study medicine gets into the bloodstream and if food affects the amount of study medicine in the blood in healthy participants (Part C),
• how the study medicine is broken down and leaves the body in healthy participants (Optional Part D),
• how the study medicine is processed in adults with mild-to-moderate asthma (Optional Part E),
• if taking the study medicine together with another medicine affects how each medicine is processed by the body in healthy participants (Optional Part F).

Participants will take part in the study for about 10 weeks (Parts A and F), 12 weeks (Part B), 9 weeks (Parts C and D), and 16 weeks (Part E).

During this time, they will have 2 study visits at the study clinic and up to 28 overnight stays (Part A), 18 overnight stays (Parts B and E), 10 overnight stays (Part C), 11 overnight stays (Part D), and 16 overnight stays (Part F). The study team will also call participants 1 time over the phone at the end of the study to assess how they are doing.

Study measurements will be taken by body examination, monitoring side effects, blood and urine tests, heart tests (ECG), vital signs (blood pressure and pulse), questionnaires (Parts C and E), stool samples (Part D only), and breathing tests (Part E only).

Study Overview

• Status: Recruiting
• Conditions: Asthma; Healthy Participants; Healthy Adults; Healthy Volunteer Study
• Intervention / Treatment: Drug: Midazolam; Drug: PF-08103402; Drug: Placebo

• Study Type: Interventional
• Enrollment (Estimated): 139
• Phase: Phase 1

Contacts and Locations

• Study Contact: Name: Pfizer CT.gov Call Center; Phone Number: 1-800-718-1021; Email: ClinicalTrials.gov_Inquiries@pfizer.com

Study Locations

• United States
  • Connecticut
    • New Haven, Connecticut, United States, 06511
      • Recruiting
      • Pfizer Clinical Research Unit - New Haven

Participation Criteria

Eligibility Criteria

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

Description

Key Inclusion criteria (Parts A, B, C, D and F):

1. Are males or females who can no longer have children,
2. Are 18 to 65 years old,
3. Have a body mass index (BMI) of 16 to 32 kilograms per meter squared and a total body weight of more than 50 kilograms (110 pounds).

For Part A (Optional group or cohort 3: Japanese participants only):

1. A total body weight of more than 45 kg (100 pounds).
2. Have 4 biological Japanese grandparents who were born in Japan.

For Part E only:

Adults with a documented doctor's-diagnosis history of asthma for at least 12 months before entering the study.

1. Have a body mass index (BMI) of 16 to 35 kilograms per meter squared and a total body weight of more than 50 kilograms (110 pounds).

Key Exclusion criteria

1. Evidence or history of clinically significant medical conditions.
2. History of human immunodeficiency virus (HIV) infection, hepatitis B, or hepatitis C; positive testing for HIV, hepatitis B surface antigen (HBsAg), or hepatitis C antibody (HCVAb).
3. History of alcohol abuse or binge drinking and/or any other illicit drug use or dependence within 6 months of Screening.
4. Participation in studies of other investigational products (drug or vaccine) at any time during their participation in this study.
5. Any history of parasitic infection requiring treatment within 28 days prior to screening.
6. Positive tuberculosis infection test result.
7. Part C only: Evidence or history of conditions interfering with the ability to taste.
8. Part D only: History of irregular bowel movements.
9. Part E only: Evidence of lung disease(s) other than asthma.
10. Part E only: Asthma exacerbation within 3 months prior to screening.
11. Part F only: History of acute narrow-angle glaucoma, untreated open-angle glaucoma, sleep apnea, respiratory insufficiency, myasthenia gravis or adverse reaction to midazolam or other benzodiazepines.

Study Plan

How is the study designed?

Design Details

• Primary Purpose: Basic Science
• Allocation: Randomized
• Interventional Model: Crossover Assignment
• Masking: Double

Number of Arms

6

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
Placebo Comparator: Part A: Cohorts 1, 2 and Optional Cohort 3; PF-08103402 as suspension or matching placebo as a single oral dose on Day 1 of each period	Drug: PF-08103402; Oral suspension (Parts A to F); Tablets (Parts C and F only); Drug: Placebo; Oral suspension (Parts A, B and E).
Placebo Comparator: Part B: Cohorts 4, 5, 6, 7, and Optional Cohort 8; PF-08103402 as suspension or matching placebo given once daily oral doses from Day 1 through Day 14.	Drug: PF-08103402; Oral suspension (Parts A to F); Tablets (Parts C and F only); Drug: Placebo; Oral suspension (Parts A, B and E).
Other: Part C: Cohort 9; PF-08103402 as a single oral dose as suspensions or tablets on Day 1 of each period	Drug: PF-08103402; Oral suspension (Parts A to F); Tablets (Parts C and F only)
Other: Part D: Cohort 10 (Optional); PF-08103402 as a single oral dose as suspension on Day 1.	Drug: PF-08103402; Oral suspension (Parts A to F); Tablets (Parts C and F only)
Placebo Comparator: Part E: Cohorts 11 (Optional) and 12 (Optional); PF-08103402 as suspension or corresponding placebo as oral doses from Day 1 through Day 14.	Drug: PF-08103402; Oral suspension (Parts A to F); Tablets (Parts C and F only); Drug: Placebo; Oral suspension (Parts A, B and E).
Other: Part F: Cohort 13 (Optional); Period 1: Single oral dose of midazolam on Day 1. Period 2: Once daily oral dose of PF-08103402 as suspension or tablet from Day 1 through Day 14 and a single oral dose of midazolam on Day 14.	Drug: Midazolam; Oral syrup; Drug: PF-08103402; Oral suspension (Parts A to F); Tablets (Parts C and F only)

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Number of Participants with Treatment Emergent Adverse Events (TEAEs)	Part A: Cohorts 1, 2 and Cohort 3 (optional). Part B: Cohorts 4, 5, 6, and 7 and Cohort 8 (optional). Part E: Cohorts 11 (optional) and 12 (optional)	Parts A: Up to Day 36; Part B and E: Up to Day 50
Number of Participants with Serious Adverse Events (SAEs)	Part A: Cohorts 1, 2 and Cohort 3 (optional). Part B: Cohorts 4, 5, 6, and 7 and Cohort 8 (optional). Part E: Cohorts 11 (optional) and 12 (optional)	Parts A: Up to Day 36; Part B and E: Up to Day 50
Number of Participants With Clinically Significant Change From Baseline in Laboratory Abnormalities	Part A: Cohorts 1, 2 and Cohort 3 (optional). Part B: Cohorts 4, 5, 6, and 7 and Cohort 8 (optional). Part E: Cohorts 11 (optional) and 12 (optional)	Parts A: Change From Baseline to Day 7; Part B and E: Change From Baseline to Day 17
Number of Participants With Clinically Significant Change From Baseline in Vital Signs	Part A: Cohorts 1, 2 and Cohort 3 (optional). Part B: Cohorts 4, 5, 6, and 7 and Cohort 8 (optional). Part E: Cohorts 11 (optional) and 12 (optional).	Parts A: Change From Baseline to Day 7; Part B and E: Change From Baseline to Day 17
Number of Participants With Clinically Significant Change From Baseline in Electrocardiogram (ECG) Findings	Part A: Cohorts 1, 2 and Cohort 3 (optional). Part B: Cohorts 4, 5, 6, and 7 and Cohort 8 (optional). Part E: Cohorts 11 (optional) and 12 (optional).	Parts A: Change From Baseline to Day 7; Part B and E: Change From Baseline to Day 17
Area under the curve from time zero to extrapolated infinite time (AUCinf) if data permit, otherwise (AUClast) in the fasted state	Part C: Cohort 9	Pre-dose (Hour 0) and at 0.5, 1, 1.5, 2, 3, 4, 6, 8, 12 hours post-dose on Day 1
Maximum observed plasma concentration (Cmax) in the fasted state	Part C: Cohort 9	Pre-dose (Hour 0) and at 0.5, 1, 1.5, 2, 3, 4, 6, 8, 12 hours post-dose on Day 1
Total recovery of drug-related material in urine and feces separately, and both routes combined, expressed as a percent of total dose administered	Part D: Cohort 10 (optional)	Pre-dose (Hour 0) and at 1.5, 2, 3, 4, 6, 8, 12 hours post-dose on Day 1 and at 24 hours post-dose (Day 2)
Maximum observed plasma concentration (Cmax)	Part F: Cohort 13 (optional)	Pre-dose (Hour 0) and at 0.5, 1, 2, 4, 6, 8, 12 hours post-dose on Day 1 and at 24 hours post-dose (Day 2)
Area under the curve from time zero to extrapolated infinite time (AUCinf) if data permit, otherwise AUClast	Part F: Cohort 13 (optional)	Pre-dose (Hour 0) and at 0.5, 1, 2, 4, 6, 8, 12 hours post-dose on Day 1 and at 24 hours post-dose (Day 2)

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Area under the concentration-time curve from time zero to the time of the last quantifiable concentration (AUClast)	Part A: Cohorts 1, 2 and Cohort 3 (optional).	Pre-dose (Hour 0) and at 0.5, 1, 1.5, 2, 3, 4, 6, 8, 12 hours post-dose on Day 1 and at 24 and 36 hours post-dose (Day 2)
Maximum observed plasma concentration (Cmax)	Part A: Cohorts 1, 2 and Cohort 3 (optional).	Pre-dose (Hour 0) and at 0.5, 1, 1.5, 2, 3, 4, 6, 8, 12 hours post-dose on Day 1 and at 24 and 36 hours post-dose (Day 2)
Time of Maximum observed plasma concentration (Tmax)	Part A: Cohorts 1, 2 and Cohort 3 (optional).	Pre-dose (Hour 0) and at 0.5, 1, 1.5, 2, 3, 4, 6, 8, 12 hours post-dose on Day 1 and at 24 and 36 hours post-dose (Day 2)
Area under the curve from time zero to extrapolated infinite time (AUCinf) if data permit	Part A: Cohorts 1, 2 and Cohort 3 (optional).	Pre-dose (Hour 0) and at 0.5, 1, 1.5, 2, 3, 4, 6, 8, 12 hours post-dose on Day 1 and at 24 and 36 hours post-dose (Day 2)
Half-life (t½) if data permit	Part A: Cohorts 1, 2 and Cohort 3 (optional)	Pre-dose (Hour 0) and at 0.5, 1, 1.5, 2, 3, 4, 6, 8, 12 hours post-dose on Day 1 and at 24 and 36 hours post-dose (Day 2)
Area under the curve over 1 dosing interval (AUCtau)	Part B: Cohorts 4, 5, 6, and 7 and Cohort 8 (optional).	Pre-dose (Hour 0) and at 0.5, 1, 1.5, 2, 3, 4, 6, 8, 12 and 24 hours post-dose on Day 1, Day 7 and Day 14
Maximum observed plasma concentration (Cmax)	Part B: Cohorts 4, 5, 6, and 7 and Cohort 8 (optional).	Pre-dose (Hour 0) and at 0.5, 1, 1.5, 2, 3, 4, 6, 8, 12 and 24 hours post-dose on Day 1, Day 7 and Day 14
Time of Maximum observed plasma concentration (Tmax)	Part B: Cohorts 4, 5, 6, and 7 and Cohort 8 (optional).	Pre-dose (Hour 0) and at 0.5, 1, 1.5, 2, 3, 4, 6, 8, 12 and 24 hours post-dose on Day 1, Day 7 and Day 14
Half-life (t½) if data permit	Part B: Cohorts 4, 5, 6, and 7 and Cohort 8 (optional).	Pre-dose (Hour 0) and at 0.5, 1, 1.5, 2, 3, 4, 6, 8, 12 and 24 hours post-dose on Day 1, Day 7 and Day 14
Number of Participants with Treatment Emergent Adverse Events (TEAEs)	Part C: Cohort 9	Up to Day 36
Number of Participants With Serious Adverse Events (SAEs)	Part C: Cohort 9	Up to Day 36
Number of Participants With Clinically Significant Change From Baseline in Laboratory Abnormalities	Part C: Cohort 9	Change From Baseline to Day 4
Number of Participants With Clinically Significant Change From Baseline in Vital Signs	Part C: Cohort 9	Change From Baseline to Day 4
Number of Participants With Clinically Significant Change From Baseline in Electrocardiogram (ECG) Findings	Part C: Cohort 9	Change From Baseline to Day 4
Number of Participants with Treatment Emergent Adverse Events (TEAEs)	Part D: Cohort 10 (optional)	Up to Day 36
Number of Participants With Serious Adverse Events (SAEs)	Part D: Cohort 10 (optional)	Up to Day 36
Number of Participants With Clinically Significant Change From Baseline in Laboratory Abnormalities	Part D: Cohort 10 (optional)	Change From Baseline to Day 11
Number of Participants With Clinically Significant Change From Baseline in Vital Signs	Part D: Cohort 10 (optional)	Change From Baseline to Day 11
Number of Participants With Clinically Significant Change From Baseline in Electrocardiogram (ECG) Findings	Part D: Cohort 10 (optional)	Change From Baseline to Day 11
Area under the curve from time zero to extrapolated infinite time (AUCinf) if data permit, otherwise AUClast	Part D: Cohort 10 (optional)	Pre-dose (Hour 0) and at 0.5, 1, 1.5, 2, 3, 4, 6, 8, 12 hours post-dose on Day 1, 24 hours post-dose (Day 2), 48 hours post-dose (Day 3), 72 hours post-dose (Day 4), 96 hours post-dose (Day 5), 120 hours post-dose (Day 6), 144 hours post-dose (Day 7)
Maximum observed plasma concentration (Cmax)	Part D: Cohort 10 (optional)	Pre-dose (Hour 0) and at 0.5, 1, 1.5, 2, 3, 4, 6, 8, 12 hours post-dose on Day 1, 24 hours post-dose (Day 2), 48 hours post-dose (Day 3), 72 hours post-dose (Day 4), 96 hours post-dose (Day 5), 120 hours post-dose (Day 6), 144 hours post-dose (Day 7).
Change From Baseline (CFB) in Fractional concentration of exhaled Nitric Oxide (FeNO) at Day 14	Part E: Cohorts 11 (optional) and 12 (optional)	Pre-dose (Hour 0) and at 72 hours post-dose (Day 4), 144 hours post-dose (Day 7), 264 hours post-dose (Day 12), 312 hours post-dose (Day 14) and 384 hours post-dose (Day 17)
Area under the curve over 1 dosing interval (AUCtau)	Part E: Cohorts 11 (optional) and 12 (optional)	Pre-dose (Hour 0), 0.5, 1, 1.5, 2, 3, 4, 6, 8, 12 hours post-dose (Day 1); 24 hours post-dose (Day 2); 144 hours post-dose (Day 7); 312 hours post-dose (Day 14); 336 hours post-dose (Day 15); 360 hours post-dose (Day 16); 384 hours post-dose (Day 17)
Maximum observed plasma concentration (Cmax)	Part E: Cohorts 11 (optional) and 12 (optional)	Pre-dose (Hour 0), 0.5, 1, 1.5, 2, 3, 4, 6, 8, 12 hours post-dose (Day 1); 24 hours post-dose (Day 2); 144 hours post-dose (Day 7); 312 hours post-dose (Day 14); 336 hours post-dose (Day 15); 360 hours post-dose (Day 16); 384 hours post-dose (Day 17)
Time of Maximum observed plasma concentration (Tmax)	Part E: Cohorts 11 (optional) and 12 (optional)	Pre-dose (Hour 0), 0.5, 1, 1.5, 2, 3, 4, 6, 8, 12 hours post-dose (Day 1); 24 hours post-dose (Day 2); 144 hours post-dose (Day 7); 312 hours post-dose (Day 14); 336 hours post-dose (Day 15); 360 hours post-dose (Day 16); 384 hours post-dose (Day 17)
Half-life (t½) if data permit	Part E: Cohorts 11 (optional) and 12 (optional)	Pre-dose (Hour 0), 0.5, 1, 1.5, 2, 3, 4, 6, 8, 12 hours post-dose (Day 1); 24 hours post-dose (Day 2); 144 hours post-dose (Day 7); 312 hours post-dose (Day 14); 336 hours post-dose (Day 15); 360 hours post-dose (Day 16); 384 hours post-dose (Day 17)
Number of Participants With Treatment Emergent Adverse Events (TEAEs)	Part F: Cohort 13 (optional)	Up to Day 51
Number of Participants With Serious Adverse Events (SAEs)	Part F: Cohort 13 (optional)	Up to Day 51
Number of Participants With Clinically Significant Change From Baseline in Vital Signs	Part F: Cohort 13 (optional)	Change From Baseline to Day 16
Number of Participants With Clinically Significant Change From Baseline in Electrocardiogram (ECG) Findings	Part F: Cohort 13 (optional)	Change From Baseline to Day 16
Area under the curve over 1 dosing interval (AUCtau)	Part F: Cohort 13 (optional)	Pre-dose (Hour 0) and at 0.5, 1, 2, 3, 4, 6, 8, 12 hours post-dose on Day 1 and at 24 hours post-dose (Day 2)
Maximum observed plasma concentration (Cmax)	Part F: Cohort 13 (optional)	Pre-dose (Hour 0) and at 0.5, 1, 2, 3, 4, 6, 8, 12 and 24 hours post-dose on Day 1 (Period 1 ) and on Day 1 and Day 14 (Period 2)
Time of Maximum observed plasma concentration (Tmax)	Part F: Cohort 13 (optional)	Pre-dose (Hour 0) and at 0.5, 1, 2, 3, 4, 6, 8, 12 and 24 hours post-dose on Day 1 (Period 1 ) and on Day 1 and Day 14 (Period 2)
Half-life (t½) if data permit	Part F: Cohort 13 (optional)	Pre-dose (Hour 0) and at 0.5, 1, 2, 3, 4, 6, 8, 12 and 24 hours post-dose on Day 1 (Period 1 ) and on Day 1 and Day 14 (Period 2)

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): June 17, 2026
• Primary Completion (Estimated): June 18, 2027
• Study Completion (Estimated): June 18, 2027

Study Registration Dates

• First Submitted: June 16, 2026
• First Submitted That Met QC Criteria: June 16, 2026
• First Posted (Actual): June 22, 2026

Study Record Updates

• Last Update Posted (Actual): June 29, 2026
• Last Update Submitted That Met QC Criteria: June 24, 2026
• Last Verified: June 1, 2026

More Information

Terms related to this study

• Keywords: Food effect; Randomized; Human; Metabolism; Excretion; Drug-Drug Interaction
• Additional Relevant MeSH Terms: Immune System Diseases; Respiratory Tract Diseases; Lung Diseases; Bronchial Diseases; Lung Diseases, Obstructive; Respiratory Hypersensitivity; Hypersensitivity, Immediate; Hypersensitivity; Asthma; Heterocyclic Compounds; Heterocyclic Compounds, 2-Ring; Heterocyclic Compounds, Fused-Ring; Benzazepines; Benzodiazepines; Midazolam
• Other Study ID Numbers: C6611001; 2026-526260-21-00 (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