Bioavailability of SC Formulation and Japanese Ethnobridging Study for PRA023

Inclusion Criteria: * Subjects are required to meet the following criteria in order to be included in the study: 1. Japanese subjects must have both natural (not adopted) parents and four grandparents of Japanese origin. 2. Caucasian subjects must be of European or Latin American descent (i.e., White). 3. Male or female (of non-childbearing potential only) between minimum adult legal age (according to local laws for signing the informed consent document) and 55 years of age. 4. Females must be of non-childbearing potential and must have undergone one of the following sterilization procedures, and have official documentation, at least 6 months prior to the first dose: 1. hysteroscopic sterilization; 2. bilateral tubal ligation or bilateral salpingectomy; 3. hysterectomy; 4. bilateral oophorectomy, or; 5. be postmenopausal with amenorrhea for at least 1 year prior to the first dose and have FSH serum levels consistent with postmenopausal status as per Investigator judgment. 5. Male subjects must use reliable forms of contraception during sexual intercourse with female partners from screening to 30 days after the end of dosing. 6. Good general health as determined by medical history, and by results of physical examination, chest x-ray, vital signs, ECG, and clinical laboratory tests obtained within 28 days (4 weeks) prior to study drug administration. Exclusion Criteria: * Subjects with the following characteristics will be excluded from the study: 1. History or presence of any clinically significant organ system disease that could interfere with the objectives of the study or the safety of the subjects. 2. Blood pressure and heart rate are outside the ranges 90-140 mmHg systolic, 60-90mmHg diastolic, heart rate 60-100 beats/min. 3. 12-lead ECG with any abnormality judged by the Investigator to be clinically significant, QRS \>= 120 milliseconds (msec), or QTcF interval of \> 450 msec for men or \> 470msec for women. 4. Presence or history of any abnormality or illness, which in the opinion of the Investigator may affect absorption, distribution, metabolism or elimination of the study drug. 5. Any screening laboratory evaluation outside the laboratory reference range that is judged by the Investigator to be clinically significant. 6. History of or current active tuberculosis (TB) infection; history of latent TB that has not been fully treated or current latent TB infection as indicated by a positive QuantiFERON-TB test. 7. History of significant allergy to any medication as judged by the Investigator. 8. History of alcohol or drug abuse within the past 24 months.