First-in-Human Study to Evaluate Safety and Tolerability of Single and Multiple Ascending Doses of Janus Kinase-1 Inhibitor PF-04965842 in Healthy Western and Japanese Subjects

Inclusion Criteria:

- Healthy male and/or female subjects between the ages of 18 and 55 years, inclusive.

- Females must be of non-child bearing potential and either at least 1 year post
menopausal (FSH ≥40 IU/L), or have documented hysterectomy (with or without bilateral
oophrectomy) at least 6 months prior to study day

- Subjects willing to defer receiving prophylactic immunizations (e.g. influenza or
pneumococcal vaccines) during the study.

- Absolute lymphocyte count must be greater than or equal to the lower limit of the
laboratory reference range.

- Subjects enrolled in Cohort 8 must have four Japanese grandparents born in Japan.

Exclusion Criteria:

- Evidence or history of clinically significant hematological, renal, , pulmonary,
gastrointestinal, cardiovascular, hepatic, psychiatric, neurologic, or allergic
disease (including drug allergies, but excluding untreated, asymptomatic, seasonal
allergies at time of dosing).

- History of hepatitis or positive testing for human immunodeficiency virus (HIV),
hepatitis B surface antigen (HBsAg), hepatitis B core antibody (HBc Ab) or hepatitis
C antibodies (HCV).

- Clinically significant abnormality on chest X-ray performed at screening or within 3
months of screening date; or history of tuberculosis or active or latent or
inadequately treated infection.