Healthy VolunteersPhase 1NCT06172348

A Study to Learn About Three Forms of The Study Medicine (Ritlecitinib) in Healthy Adults

A Phase 1 study testing Ritlecitinib in people with Healthy Volunteers, run by Pfizer at 1 site in Belgium.

Completed

Finished. The study has ended and is not enrolling. Results may be posted on the official record.

Trial summary

The purpose of this study is to compare if three forms of study medicine (called ritlecitinib) get processed differently in healthy adults. This study is seeking healthy participants who have: Aged 18 years or older; male or female who are healthy as determined by medical assessment; BMI of 16-32 kg/m2, and a total… Read more about this study

Who is it for?: Ages 18 years and olderHealthy volunteers can take part
Conditions the study is for: Healthy Volunteers
What is being tested?: Ritlecitinib
Type of treatment: Pill or oral medicine
Could I receive a placebo?: No, everyone receives an active treatment
How many people: 12 participants
Where: 1 siteBelgium
Study dates: 1 Feb 2024to 28 Mar 2024
Phase: Phase 1
Are there results?: Yes, posted in the registrySummary in the doctors' view

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

Male and female participants aged 18 years or older (or the minimum age of consent in accordance with local regulations) at screening who are overtly healthy as determined by medical evaluation including medical history, physical examination, and laboratory tests.
BMI of 16-32 kg/m2, and a total body weight >45 kg (99 lb).
Participants who are willing and able to comply with all scheduled visits, treatment plan, laboratory tests, lifestyle considerations, and other study procedures.
Capable of giving signed informed consent

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).
Participants with the acute or chronic infections or infection history
History of febrile illness within 5 days prior to the first dose of study intervention.
History of any lymphoproliferative disorder such as EBV related lymphoproliferative disorder, history of lymphoma, history of leukemia, or signs or symptoms suggestive of current lymphatic or lymphoid disease.
Known present or a history of malignancy other than a successfully treated or excised nonmetastatic basal cell or squamous cell cancer of the skin or cervical carcinoma in situ.
History of active or latent Mycobacterium TBA: participant who is currently being treated for active or latent Mycobacterium TB infection or has a history of Mycobacterium TB must be excluded from the study.
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.

Trial locations and contacts

1 site in 1 country.

Belgium1 site

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

Other trials in Belgium

About this study

Official title: A PHASE 1, OPEN-LABEL STUDY IN HEALTHY PARTICIPANTS TO INVESTIGATE THE PHARMACOKINETICS OF RITLECITINIB FOLLOWING SINGLE ORAL ADMINISTRATION OF MODIFIED RELEASE FORMULATIONS UNDER FED AND FASTED CONDITIONS

The purpose of this study is to compare if three forms of study medicine (called ritlecitinib) get processed differently in healthy adults.

This study is seeking healthy participants who have:

Aged 18 years or older;
male or female who are healthy as determined by medical assessment;
BMI of 16-32 kg/m2, and a total body weight >45 kg (99 lb).

All participants in this study will receive a ritlecitinib oral dose in three different forms (solution, capsule 1 and capsule 2).

The study will take up to 2.5 months, including the screening period and follow-up phone call. Participants will have to stay at the study clinic for at least 13 days. There will be 4 periods in total for this study. On day 1 of each period, participants will take one form of Riltecitinib without food for the first three periods and with food for the last period. Participants will have blood samples taken both before and after taking ritlecitinib. A follow-up phone call will be made at 28 to 35 days after the last study period.

Read the detailed description

Ritlecitinib is a covalent and irreversible inhibitor of JAK3 with high selectivity over the other JAK isoforms (JAK1, JAK2, and TYK2). Ritlecitinib also inhibits irreversibly the TEC family kinases with selectivity over the broader human kinome. Treatment with ritlecitinib is expected to inhibit the inflammatory pathways mediated by IL 7, IL 15 and IL 21, all implicated in UC, CD, AA, RA, and vitiligo and therefore under development in these indications. Moreover, due to lack of activity against the other JAK isoforms, ritlecitinib is expected to spare immunoregulatory cytokines such as IL 10, IL 27 and IL 35, which are critical to the maintenance of immunosuppressive functions and immune homeostasis.

This study aims to investigate the pharmacokinetics (PK) and relative bioavailability of 2 new modified release (MR) capsule formulations of ritlecitinib, MR1 (release duration: 6-8 hours) and MR2 (release duration:13 15 hours) as single doses in fasted and fed conditions.

This is a single dose, open-label, randomized, 4-period, 6-sequence crossover study in a single cohort of approximately 12 healthy participants randomized to one of the sequences (containing 1 solution and 2 modified release [MR1 and MR2] capsule formulations of ritlecitinib) described in the table below. The first 3 periods are under fasted condition and the fourth period is under fed condition to investigate the effect of food on the PK of MR1 and MR2.

For a given participant, the total study duration from screening to follow-up phone call will be between approximately 8 to 11 weeks.

Screening will occur within 28 days prior to the first dose of the study intervention. Each participant will go through Periods 1 through 4 and dosing in each treatment period will be separated by at least 3 days to minimize any carryover effect.

Venous PK blood samples for PK analysis will be collected pre-dose and post-dose in each period.

Conditions: Healthy Volunteers
Being tested: Ritlecitinib
Keywords: Pharmacokinetics, Adults

What participants receive

What participants receive. In a randomised study each person is assigned to one group by chance.

RitlecitinibDrug
Also called PF-06651600
Ritlecitinib 100 milligrams (mg) will be provided as either solution or capsule formulation (2 capsules of 50 mg)

Study groups in NCT06172348
Study group	Role	What they receive
Treatment Sequence 1	Experimental	Ritlecitinib 100 mg solution (fasted, Period 1), followed by ritlecitinib 100 mg MR capsule 1 (fasted, Period 2), followed by ritlecitinib 100 mg MR capsule 2 (fasted, Period 3), and followed by ritlecitinib 100 mg MR capsule 1 (fed, Period 4) Receives: Drug: Ritlecitinib
Treatment Sequence 2	Experimental	Ritlecitinib 100 mg MR capsule 1 (fasted, Period 1), followed by ritlecitinib 100 mg MR capsule 2 (fasted, Period 2), followed by ritlecitinib 100 mg solution (fasted, Period 3), and followed by ritlecitinib 100 mg MR capsule 1 (fed, Period 4) Receives: Drug: Ritlecitinib
Treatment Sequence 3	Experimental	Ritlecitinib 100 mg MR capsule 2 (fasted, Period 1), followed by ritlecitinib 100 mg solution (fasted, Period 2), followed by ritlecitinib 100 mg MR capsule 1 (fasted, Period 3), and followed by ritlecitinib 100 mg MR capsule 1 (fed, Period 4) Receives: Drug: Ritlecitinib
Treatment Sequence 4	Experimental	Ritlecitinib 100 mg solution (fasted, Period 1), followed by ritlecitinib 100 mg MR capsule 1 (fasted, Period 2), followed by ritlecitinib 100 mg MR capsule 2 (fasted, Period 3), and followed by ritlecitinib 100 mg MR capsule 2 (fed, Period 4) Receives: Drug: Ritlecitinib
Treatment Sequence 5	Experimental	Ritlecitinib 100 mg MR capsule 1 (fasted, Period 1), followed by ritlecitinib 100 mg MR capsule 2 (fasted, Period 2), followed by ritlecitinib 100 mg solution (fasted, Period 3), and followed by ritlecitinib 100 mg MR capsule 2 (fed, Period 4) Receives: Drug: Ritlecitinib
Treatment Sequence 6	Experimental	Ritlecitinib 100 mg MR capsule 2 (fasted, Period 1), followed by ritlecitinib 100 mg solution (fasted, Period 2), followed by ritlecitinib 100 mg MR capsule 1 (fasted, Period 3), and followed by ritlecitinib 100 mg MR capsule 2 (fed, Period 4) Receives: Drug: Ritlecitinib

What is being measured

The primary outcome is the main question the study is designed to answer.

Maximum Observed Concentration (Cmax) of Ritlecitinib: MR Capsules vs Oral Solution Under Fasted Condition
Measured: For oral solution: Pre-dose (0 hours), 0.5, 1, 2, 3, 4, 6, 10, 12 and 24 hours post-dose on Day 1 of Period 1, 2 or 3; for MR1 and MR2 capsules: Pre-dose (0 hours), 1, 2, 3, 4, 6, 10, 12,16, 24, 36 and 48 hours post-dose on Day 1 of Period 1, 2 or 3
Area Under the Plasma Concentration-Time Profile From Time Zero (0) Extrapolated to Infinite Time (AUCinf) of Ritlecitinib: MR Capsules vs Oral Solution Under Fasted Condition
AUCinf was calculated as AUClast + (Clast/kel), where Clast was the predicted plasma concentration at the last quantifiable time point from the log-linear regression analysis and kel was the terminal phase rate constant calculated by a linear regression of the log-linear concentration-time curve.
Measured: For oral solution: Pre-dose (0 hours), 0.5, 1, 2, 3, 4, 6, 10, 12 and 24 hours post-dose on Day 1 of Period 1, 2 or 3; for MR1 and MR2 capsules: Pre-dose (0 hours), 1, 2, 3, 4, 6, 10, 12,16, 24, 36 and 48 hours post-dose on Day 1 of Period 1, 2 or 3

Secondary outcomes (6)

Cmax of Ritlecitinib: MR Capsules Under Fed vs Fasted Condition
Measured: Pre-dose (0 hours), 1, 2, 3, 4, 6, 10, 12,16, 24, 36 and 48 hours post-dose on Day 1 of Period 1, 2, 3 (for fasted) or 4 (for fed)
AUCinf of Ritlecitinib: MR Capsules Under Fed vs Fasted Condition
AUCinf was calculated as AUClast + (Clast/kel), where Clast was the predicted plasma concentration at the last quantifiable time point from the log-linear regression analysis and kel was the terminal phase rate constant calculated by a linear regression of the log-linear concentration-time curve.
Measured: Pre-dose (0 hours), 1, 2, 3, 4, 6, 10, 12,16, 24, 36 and 48 hours post-dose on Day 1 of Period 1, 2, 3 (for fasted) or 4 (for fed)
Number of Participants With Adverse Events (AEs)
An AE was any untoward medical occurrence in a participant temporally associated with the use of study intervention, whether or not considered related to the study intervention.
Measured: From start of study treatment up to 35 days after administration of last dose of study intervention (maximum up to 45 days)
Number of Participants With Clinically Significant Laboratory Test Abnormalities
Laboratory parameters included: Hematology: lymphocytes/leukocytes, eosinophils/leukocytes greater than (>) 1.2*upper limit of normal (ULN) (percent [%]), neutrophils/leukocytes less than (<) 0.8*lower limit of normal (LLN) (%); Urinalysis: urine hemoglobin, nitrite greater than or equal to (>=) 1, bacteria > 20 (per high power field [/HPF]). Clinical significance was judged by investigator.
Measured: From start of study treatment up to Day 3 of Period 4 (maximum up to Day 12, each Period = 3 days)
Number of Participants With Clinically Significant Vital Signs Abnormalities
Vital signs including systolic blood pressure (SBP), diastolic blood pressure (DBP) and pulse rate (PR) were measured in a supine position. Criteria for vital signs included: SBP: value less than (<) 90 millimeter of mercury (mmHg), change greater than or equal to (>=) 30 mmHg decrease, change >= 30 mmHg increase; DBP: value < 50 mmHg, change >= 20 mmHg decrease, change >= 20 mmHg increase; PR: value < 40 beats per minute (bpm), value > 120 bpm. Clinical significance was judged by investigator.
Measured: From start of study treatment up to Day 3 of Period 4 (maximum up to Day 12, each Period = 3 days)
Number of Participants With Clinically Significant Electrocardiogram (ECG) Abnormalities
Standard 12 lead ECGs were obtained with the participant in a supine position after at least 5 minutes of rest using an ECG machine that automatically calculated the heart rate and measured PR interval, QT, corrected QT (Fridericia method) (QTcF) and QRS intervals. Clinical significance was judged by investigator.
Measured: From start of study treatment up to Day 3 of Period 4 (maximum up to Day 12, each Period = 3 days)

Timeline

From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.

1 Feb 202428 Mar 2024

First posted15 Dec 2023
Study start1 Feb 2024
Primary completion28 Mar 2024
Study completion28 Mar 2024

Resources

Official record on ClinicalTrials.govThe registry entry this page is built from, with its full change history.
Posted resultsParticipant flow, outcome measures and adverse events reported by the sponsor.
Publications (1)Papers the sponsor has linked to this study.
Other trials for Healthy VolunteersStudies 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: 12 participants (actual)

IDs, dates and publications

ClinicalTrials.gov ID: NCT06172348
Sponsor's protocol ID: B7981086
Other IDs: 2023-505603-23-00, 2023
Status last verified: Mar 2025
First submitted: 7 Dec 2023
Last updated: 10 Apr 2025
Results posted: Yes, on ClinicalTrials.gov
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.

Publications

Saadeddin A, Huh Y, Roy M, Jakuba K, Winton J, Zhao Y, Hee B, Sapone A, Kushner J 4th, Shamblin S, Kopina B. Ritlecitinib lipid microsphere development and model-facilitated determination of regional gastrointestinal delivery in healthy volunteers. J Control Release. 2026 Oct 27:115492. doi: 10.1016/j.jconrel.2026.115492. Online ahead of print.
PubMed 42946174

Want to know more?

The sponsor has not listed a contact. The official record may have more details.

Talk to your doctor first and take this page with you. Only the study team can confirm whether you can join.

Questions to ask the study team

What is the study trying to find out?
What would I need to do, and how often would I visit?
Could I receive a placebo instead of the treatment?
What are the possible risks and benefits for me?
Will it cost me anything? Are travel or time paid for?
Can I keep seeing my own doctor during the study?
What happens when the study ends?

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Study at a glance

From the registry record, last updated by the sponsor on 10 Apr 2025. Recruitment status is as the sponsor reported it: confirm with the study team.

Official title: A PHASE 1, OPEN-LABEL STUDY IN HEALTHY PARTICIPANTS TO INVESTIGATE THE PHARMACOKINETICS OF RITLECITINIB FOLLOWING SINGLE ORAL ADMINISTRATION OF MODIFIED RELEASE FORMULATIONS UNDER FED AND FASTED CONDITIONS
ClinicalTrials.gov ID: NCT06172348
Acronym / sponsor ID: B7981086
Conditions: Healthy Volunteers
Keywords: Pharmacokinetics, Adults
Phase: Phase 1
Study type: Interventional
Recruitment status: Completed
Enrolment: 12 participants (actual)
Lead sponsor: PfizerIndustry (pharma, biotech, devices)
Study start: 1 Feb 2024 (actual)
Primary completion: 28 Mar 2024 (actual)
Study completion: 28 Mar 2024 (actual)
First posted: 15 Dec 2023 (actual)
Results: Posted 10 Apr 2025

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 compare if three forms of study medicine (called ritlecitinib) get processed differently in healthy adults.

This study is seeking healthy participants who have:

Aged 18 years or older;
male or female who are healthy as determined by medical assessment;
BMI of 16-32 kg/m2, and a total body weight >45 kg (99 lb).

All participants in this study will receive a ritlecitinib oral dose in three different forms (solution, capsule 1 and capsule 2).

Detailed description

For a given participant, the total study duration from screening to follow-up phone call will be between approximately 8 to 11 weeks.

Venous PK blood samples for PK analysis will be collected pre-dose and post-dose in each period.

Study design

Primary purpose: Basic science
Allocation: Randomised
Intervention model: Crossover
Masking: None (open label)
Number of arms: 6

Arm	Type	Receives
Treatment Sequence 1	Experimental	Drug: RitlecitinibRitlecitinib 100 mg solution (fasted, Period 1), followed by ritlecitinib 100 mg MR capsule 1 (fasted, Period 2), followed by ritlecitinib 100 mg MR capsule 2 (fasted, Period 3), and followed by ritlecitinib 100 mg MR capsule 1 (fed, Period 4)
Treatment Sequence 2	Experimental	Drug: RitlecitinibRitlecitinib 100 mg MR capsule 1 (fasted, Period 1), followed by ritlecitinib 100 mg MR capsule 2 (fasted, Period 2), followed by ritlecitinib 100 mg solution (fasted, Period 3), and followed by ritlecitinib 100 mg MR capsule 1 (fed, Period 4)
Treatment Sequence 3	Experimental	Drug: RitlecitinibRitlecitinib 100 mg MR capsule 2 (fasted, Period 1), followed by ritlecitinib 100 mg solution (fasted, Period 2), followed by ritlecitinib 100 mg MR capsule 1 (fasted, Period 3), and followed by ritlecitinib 100 mg MR capsule 1 (fed, Period 4)
Treatment Sequence 4	Experimental	Drug: RitlecitinibRitlecitinib 100 mg solution (fasted, Period 1), followed by ritlecitinib 100 mg MR capsule 1 (fasted, Period 2), followed by ritlecitinib 100 mg MR capsule 2 (fasted, Period 3), and followed by ritlecitinib 100 mg MR capsule 2 (fed, Period 4)
Treatment Sequence 5	Experimental	Drug: RitlecitinibRitlecitinib 100 mg MR capsule 1 (fasted, Period 1), followed by ritlecitinib 100 mg MR capsule 2 (fasted, Period 2), followed by ritlecitinib 100 mg solution (fasted, Period 3), and followed by ritlecitinib 100 mg MR capsule 2 (fed, Period 4)
Treatment Sequence 6	Experimental	Drug: RitlecitinibRitlecitinib 100 mg MR capsule 2 (fasted, Period 1), followed by ritlecitinib 100 mg solution (fasted, Period 2), followed by ritlecitinib 100 mg MR capsule 1 (fasted, Period 3), and followed by ritlecitinib 100 mg MR capsule 2 (fed, Period 4)

Who may qualify

Ages: 18 years and older
Sex: All
Healthy volunteers: Accepted
Age groups: Adult, Older adult

Key inclusion criteria (4 listed)

Male and female participants aged 18 years or older (or the minimum age of consent in accordance with local regulations) at screening who are overtly healthy as determined by medical evaluation including medical history, physical examination, and laboratory tests.
BMI of 16-32 kg/m2, and a total body weight >45 kg (99 lb).
Participants who are willing and able to comply with all scheduled visits, treatment plan, laboratory tests, lifestyle considerations, and other study procedures.
Capable of giving signed informed consent

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).
Participants with the acute or chronic infections or infection history
History of febrile illness within 5 days prior to the first dose of study intervention.
History of any lymphoproliferative disorder such as EBV related lymphoproliferative disorder, history of lymphoma, history of leukemia, or signs or symptoms suggestive of current lymphatic or lymphoid disease.
Known present or a history of malignancy other than a successfully treated or excised nonmetastatic basal cell or squamous cell cancer of the skin or cervical carcinoma in situ.

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
RitlecitinibAlso: PF-06651600Ritlecitinib 100 milligrams (mg) will be provided as either solution or capsule formulation (2 capsules of 50 mg)	Drug	Treatment Sequence 1, Treatment Sequence 2, Treatment Sequence 3, Treatment Sequence 4, Treatment Sequence 5, Treatment Sequence 6

Primary outcome

Maximum Observed Concentration (Cmax) of Ritlecitinib: MR Capsules vs Oral Solution Under Fasted Condition
Time frame: For oral solution: Pre-dose (0 hours), 0.5, 1, 2, 3, 4, 6, 10, 12 and 24 hours post-dose on Day 1 of Period 1, 2 or 3; for MR1 and MR2 capsules: Pre-dose (0 hours), 1, 2, 3, 4, 6, 10, 12,16, 24, 36 and 48 hours post-dose on Day 1 of Period 1, 2 or 3
Area Under the Plasma Concentration-Time Profile From Time Zero (0) Extrapolated to Infinite Time (AUCinf) of Ritlecitinib: MR Capsules vs Oral Solution Under Fasted Condition
Time frame: For oral solution: Pre-dose (0 hours), 0.5, 1, 2, 3, 4, 6, 10, 12 and 24 hours post-dose on Day 1 of Period 1, 2 or 3; for MR1 and MR2 capsules: Pre-dose (0 hours), 1, 2, 3, 4, 6, 10, 12,16, 24, 36 and 48 hours post-dose on Day 1 of Period 1, 2 or 3
AUCinf was calculated as AUClast + (Clast/kel), where Clast was the predicted plasma concentration at the last quantifiable time point from the log-linear regression analysis and kel was the terminal phase rate constant calculated by a linear regression of the log-linear concentration-time curve.

6 secondary outcomes

Cmax of Ritlecitinib: MR Capsules Under Fed vs Fasted Condition
Time frame: Pre-dose (0 hours), 1, 2, 3, 4, 6, 10, 12,16, 24, 36 and 48 hours post-dose on Day 1 of Period 1, 2, 3 (for fasted) or 4 (for fed)
AUCinf of Ritlecitinib: MR Capsules Under Fed vs Fasted Condition
Time frame: Pre-dose (0 hours), 1, 2, 3, 4, 6, 10, 12,16, 24, 36 and 48 hours post-dose on Day 1 of Period 1, 2, 3 (for fasted) or 4 (for fed)
Number of Participants With Adverse Events (AEs)
Time frame: From start of study treatment up to 35 days after administration of last dose of study intervention (maximum up to 45 days)
Number of Participants With Clinically Significant Laboratory Test Abnormalities
Time frame: From start of study treatment up to Day 3 of Period 4 (maximum up to Day 12, each Period = 3 days)
Number of Participants With Clinically Significant Vital Signs Abnormalities
Time frame: From start of study treatment up to Day 3 of Period 4 (maximum up to Day 12, each Period = 3 days)
Number of Participants With Clinically Significant Electrocardiogram (ECG) Abnormalities
Time frame: From start of study treatment up to Day 3 of Period 4 (maximum up to Day 12, each Period = 3 days)

Results and safety

Results posted to the registry on 10 Apr 2025, as reported by the sponsor. Figures are copied from the record, not re-analysed. Full results on ClinicalTrials.gov.

Participant flow

Group	Started	Completed
Treatment Sequence 1: A Then B Then C Then B (Fed)	2	2
Treatment Sequence 2: B Then C Then A Then B (Fed)	2	2
Treatment Sequence 3: C Then A Then B Then B (Fed)	2	2
Treatment Sequence 4: A Then B Then C Then C (Fed)	2	2
Treatment Sequence 5: B Then C Then A Then C (Fed)	2	2
Treatment Sequence 6: C Then A Then B Then C (Fed)	2	2

Primary outcome: Maximum Observed Concentration (Cmax) of Ritlecitinib: MR Capsules vs Oral Solution Under Fasted Condition

Time frame: For oral solution: Pre-dose (0 hours), 0.5, 1, 2, 3, 4, 6, 10, 12 and 24 hours post-dose on Day 1 of Period 1, 2 or 3; for MR1 and MR2 capsules: Pre-dose (0 hours), 1, 2, 3, 4, 6, 10, 12,16, 24, 36 and 48 hours post-dose on Day 1 of Period 1, 2 or 3. Geometric mean (Geometric Coefficient of Variation). Unit: Nanogram per milliliter (ng/mL)

Measure	Ritlecitinib 100 mg Oral Solution (Fasted) n = 12	Ritlecitinib 100 mg MR1 Capsule (Fasted) n = 11	Ritlecitinib 100 mg MR2 Capsule (Fasted) n = 12
Value	671.6 (24)	145.1 (25)	84.96 (25)

Ritlecitinib 100 mg Oral Solution (Fasted) vs Ritlecitinib 100 mg MR1 Capsule (Fasted): Ratio of Adjusted Geometric Means: 21.89 (90% CI 19.31 to 24.80)
Ritlecitinib 100 mg Oral Solution (Fasted) vs Ritlecitinib 100 mg MR2 Capsule (Fasted): Ratio of Adjusted Geometric Means: 12.65 (90% CI 11.21 to 14.27)

Population analysed: Pharmacokinetic (PK) parameter set included all participants who had at least 1 PK parameter of interest quantified in at least 1 treatment period.

Primary outcome: Area Under the Plasma Concentration-Time Profile From Time Zero (0) Extrapolated to Infinite Time (AUCinf) of Ritlecitinib: MR Capsules vs Oral Solution Under Fasted Condition

Measure	Ritlecitinib 100 mg Oral Solution (Fasted) n = 12	Ritlecitinib 100 mg MR1 Capsule (Fasted) n = 11	Ritlecitinib 100 mg MR2 Capsule (Fasted) n = 12
Value	1261 (23)	1067 (28)	970.6 (22)

Ritlecitinib 100 mg Oral Solution (Fasted) vs Ritlecitinib 100 mg MR1 Capsule (Fasted): Ratio of Adjusted Geometric Means: 86.49 (90% CI 79.11 to 94.54)
Ritlecitinib 100 mg Oral Solution (Fasted) vs Ritlecitinib 100 mg MR2 Capsule (Fasted): Ratio of Adjusted Geometric Means: 76.99 (90% CI 70.65 to 83.90)

Population analysed: PK parameter set included all participants who had at least 1 PK parameter of interest quantified in at least 1 treatment period.

6 secondary outcomes are reported in the full results.

Adverse events

Time frame: From start of study treatment up to 35 days after administration of last dose of study intervention (maximum up to 45 days). Other adverse events reported at 5% frequency or more

Group	Serious adverse events	Other adverse events	Deaths
Ritlecitinib 100 mg Oral Solution (Fasted)	0 of 12 (0%)	3 of 12 (25%)	0 of 12
Ritlecitinib 100 mg MR1 Capsules (Fasted)	0 of 11 (0%)	5 of 11 (45.5%)	0 of 11
Ritlecitinib 100 mg MR2 Capsules (Fasted)	0 of 12 (0%)	3 of 12 (25%)	0 of 12
Ritlecitinib 100 mg MR1 Capsules (Fed)	0 of 5 (0%)	0 of 5 (0%)	0 of 5
Ritlecitinib 100 mg MR2 Capsules (Fed)	0 of 6 (0%)	1 of 6 (16.7%)	0 of 6

Loading the posted results from ClinicalTrials.gov…

Research links

Official record on ClinicalTrials.govLast updated by the sponsor 10 Apr 2025.
Posted resultsParticipant flow, baseline, all outcome measures and adverse events.
Derived from this study: PubMed 42946174Saadeddin A, Huh Y, Roy M, Jakuba K, Winton J, Zhao Y, Hee B, Sapone A, Kushner J 4th, Shamblin S, Kopina B. Ritlecitinib lipid microsphere development and model-facilitated determination of regional gastrointestinal delivery in healthy volunteers. J Control Release. 2026 Oct 27:115492. doi: 10.1016/j.jconrel.2026.115492. Online ahead of print.
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 Ritlecitinib in people with Healthy Volunteers, 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 4 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 10 Apr 2025. 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?

Yes. Results are posted in the registry (first posted 10 Apr 2025). A summary is in the For doctors view, and the full results are on ClinicalTrials.gov.

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 Concentration (Cmax) of Ritlecitinib: MR Capsules vs Oral Solution Under Fasted Condition (time frame: For oral solution: Pre-dose (0 hours), 0.5, 1, 2, 3, 4, 6, 10, 12 and 24 hours post-dose on Day 1 of Period 1, 2 or 3; for MR1 and MR2 capsules: Pre-dose (0 hours), 1, 2, 3, 4, 6, 10, 12,16, 24, 36 and 48 hours post-dose on Day 1 of Period 1, 2 or 3). The study lists 2 primary outcomes in all. It is what the study was designed to measure, not a finding.

Where can I read the original study information?

On the ClinicalTrials.gov record for NCT06172348, which also lists 1 linked publication.

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 10 Apr 2025.