This study is designed to evaluate the safety and plasma concentrations of PF-06669571 in healthy volunteers following single and multiple ascending doses of PF-06669571. Effect of food on PF-06669571 plasma concentrations will be be evaluated after a single dose of PF-06669571. During multiple dose phase, PF-06669571 will be administered daily for 14 days

Inclusion Criteria:

• Healthy male and/or female subjects of non-childbearing potential between the ages of 18 and 55 years, inclusive (Healthy is defined as no clinically relevant abnormalities identified by a detailed medical history, full physical examination, including blood pressure and pulse rate measurement, 12-lead ECG and clinical laboratory tests).

Female subjects of non-childbearing potential must meet at least one of the following criteria:

1. Achieved postmenopausal status, defined as follows: cessation of regular menses for at least 12 consecutive months with no alternative pathological or physiological cause; and have a serum follicle-stimulating hormone (FSH) level confirming the post-menopausal state;

2. Have undergone a documented hysterectomy and/or bilateral oophorectomy;

3. Have medically confirmed ovarian failure. All other female subjects (including females with tubal ligations and females that do NOT have a documented hysterectomy, bilateral oophorectomy and/or ovarian failure) will be considered to be of childbearing potential.

   • Body Mass Index (BMI) of 17.5 to 30.5 kg/m2; and a total body weight >50 kg (110 lbs).
   • Evidence of a personally signed and dated informed consent document indicating that the subject has been informed of all pertinent aspects of the study.
   • Subjects who are willing and able to comply with scheduled visits, treatment plan, laboratory tests, and other study procedures.

Exclusion Criteria:

• Evidence or history of clinically significant hematological, renal, endocrine, pulmonary, gastrointestinal, cardiovascular, hepatic, psychiatric, neurologic, or allergic disease (including drug allergies, but excluding untreated, asymptomatic, seasonal allergies at time of dosing).
• Treatment with an investigational drug within 30 days (or as determined by the local requirement) or 5 half-lives preceding the first dose of study medication (whichever is longer).
• Screening supine blood pressure >= 140 mm Hg (systolic) or >=90 mm Hg (diastolic), following at least 5 minutes of rest. If BP is >=140 mm Hg (systolic) or >=90 mm Hg (diastolic), repeat per local standard operating procedures (SOP). If orthostatic changes are present and deemed to be clinically significant by the investigator, Subject can be excluded.
• For subjects who answer "Yes" to the Columbia Suicide Severity Rating Scale (C-SSRS) questions 4 or 5, a risk assessment should be done by a qualified mental health professional (MHP: a psychiatrist or licensed PhD level clinical psychologist) to assess whether it is safe for the subject to participate in the study. In addition, subjects deemed by the investigator to be at significant risk of suicidal or violent behavior should be excluded.