Part A

• To measure and compare the amount of study drug in the blood after a single 200 mg dose of study drug given as the commercial tablet formulation and the Phase 3 tablet formulation under fasting conditions
• To measure and compare the amount of study drug in the blood after a single 200 mg dose given as the variant Phase 3 tablet formulation and the Phase 3 tablet formulation under fasting conditions
• To estimate the effect of food on the amount of study drug in the blood after a single 200 mg dose of the commercial formulation

Part B

• To measure and compare the amount of study drug in the blood after a single 200 mg dose given as the commercial tablet formulation and the Phase 3 tablet formulation under fasting conditions

Parts A & B

• To collect samples for genotyping (CYP2C19 and CYP2C9 - enzymes that metabolize [break down] certain medications)

  o Genotyping is the collection of a small sample of blood that contains your genes

• To evaluate the safety and tolerability of the study drug after single 200 mg doses of the three different formulations given to healthy participants

• To measure the amount of study drug in the blood after single doses of the different formulations

• To collect exploratory samples for biobanking o Biobanking is the collection and storage of blood samples for possible future testing

The purpose of this study in healthy participants is to estimate the bioavailability (BA) of the commercial formulation of PF-04965842 and a variant formulation with slower dissolution relative to the Phase 3 formulation, to demonstrate the bioequivalence (BE) of the commercial formulation relative to the Phase 3 formulation, and to estimate the effect of food on the BA of the commercial formulation. This study consists of 2 parts: Part A is to estimate the relative BA (rBA) of single 200 mg doses of the commercial tablet formulation of PF-04965842 and a variant formulation of slower dissolution rate compared to the Phase 3 tablet formulation. The effect of food on the BA of the commercial tablet formulation will also be evaluated. Part B is to establish BE between the Phase 3 and commercial formulations. The study will follow a staged approach as the sample size for BE cannot be determined with currently available information.

Therefore, it is proposed to assess the maximum observed concentration (Cmax) and area under the curve (AUC) ratios between the Phase 3 and commercial formulations as well as the within-participant variability of Cmax and AUC values determined in Part A. Based on the results from Part A, the sample size of Part B will be determined and the decision to proceed to Part B will be made.

Inclusion Criteria:

• Body mass index (BMI) of 17.5 to 30.5 kg/m2; and a total body weight >50 kg (110 lb)

Exclusion Criteria:

• Any condition possibly affecting drug absorption (eg, gastrectomy).

  • History of human immunodeficiency virus (HIV) infection, hepatitis B, or hepatitis
  • Evidence or history of clinically significant dermatological condition (eg, atopic dermatitis or psoriasis) .History of tuberculosis (TB) (active or latent) or inadequately treated TB infection.
  • History of chronic infections, history of recurrent infections, history of latent infections, .History of disseminated herpes zoster, or disseminated herpes simplex, or recurrent localized dermatomal herpes zoster.
  • history of malignancies with the exception of adequately treated or excised non-metastatic basal cell or squamous cell cancer of the skin, or cervical carcinoma in situ

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.