Pharmacokinetic Interaction Study to Assess the Effect of ASP015K on Tacrolimus in Healthy Volunteers

Inclusion Criteria: * If female, the subject is at least 2 years post menopausal or is surgically sterile per documentation provided by a third party medical professional and the subject is not pregnant as documented by a negative serum pregnancy test * If male, the subject agrees to sexual abstinence and/or to use a highly effective method of birth control during the study period * Subject is medically healthy, with no clinically significant medical history or abnormalities observed upon physical examination or 12-lead electrocardiogram (ECG) * Subjects must weigh at least 45 kg and have a body mass index (BMI) of 18-32 kg/m2 Exclusion Criteria: * Subject has a history of chronic diarrhea * Subject has been vaccinated within the last 60 days prior to study drug administration * The subject has a previous history of any clinically significant neurological, gastro-intestinal, renal, hepatic, pulmonary, metabolic, cardiovascular, psychiatric, endocrine, hematological disorder or disease * Subject has a positive test for hepatitis C antibody, or positive for hepatitis B surface antigen (HBsAg) * Subject has a history of the human immunodeficiency virus (HIV) antibody * The subject has an absolute neutrophil count (ANC) \< 2500 cells/mm3 Subject has had clinically significant illness within 1 month prior to study drug administration * Subject has a recent history (within the last 6 months) of drug or alcohol abuse or a positive urine screen for alcohol or drugs of abuse/illegal drugs