This study is an open-label, randomized, single-dose, 4-period, 4-sequence, crossover study in a single cohort of approximately 12 healthy adult participants. The purpose of this study is to evaluate the relative bioavailability of a newly developed modified release (MR) tablet formulation of PF-06865571 relative to an immediate release (IR) tablet formulation of PF-06865571 under fed conditions. In addition, this study will also assess the relative bioavailability of the MR formulation under fasted conditions relative to fed conditions, in healthy adult participants. Study results will be used to determine if the new MR formulation may be suitable for use in future clinical studies with PF-06865571. Healthy adult Japanese participants will also be enrolled in this study to support inclusion of Japanese participants in future clinical studies.

Inclusion Criteria:

• Female participants of non-childbearing potential and male participants who are overtly healthy as determined by medical evaluation including medical history, physical examination, laboratory tests, and cardiac tests.
• Body mass index (BMI) of 17.5 to 30.5 kg/m2; and a total body weight >50 kg (110 lb).
• Participants enrolling as Japanese must have 4 biological Japanese grandparents who were born in Japan.

Exclusion Criteria:

• 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).
• Use of prescription or nonprescription drugs and dietary and herbal supplements within 7 days or 5 half-lives (whichever is longer) prior to the first dose of investigational product.
• Previous administration with an investigational drug within 30 days (or as determined by the local requirement) or 5 half-lives preceding the first dose of investigational product used in this study (whichever is longer).
• Screening supine blood pressure (BP) ≥140 mm Hg (systolic) or ≥90 mm Hg (diastolic), following at least 5 minutes of supine rest.
• Baseline 12-lead electrocardiogram (ECG) that demonstrates clinically relevant abnormalities that may affect participant safety or interpretation of study results (eg, baseline corrected QT (QTc) interval >450 msec, complete left bundle branch block [LBBB], signs of an acute or indeterminate-age myocardial infarction, ST-T interval changes suggestive of myocardial ischemia, second- or third-degree atrioventricular [AV] block, or serious bradyarrhythmias or tachyarrhythmias).
• Participants with any of the following abnormalities in clinical laboratory tests at screening: Aspartate aminotransferase (AST) or alanine aminotransferase (ALT) level ≥1.25× upper limit of normal (ULN); Total bilirubin level ≥1.5× ULN; participants with a history of Gilbert's syndrome may have direct bilirubin measured and would be eligible for this study provided the direct bilirubin level is ≤ ULN.

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.