The purpose of the study is to assess the effect of multiple doses of isavuconazole on the pharmacokinetics (PK) of sirolimus after single dose administration.

Subjects will receive a single dose of sirolimus on Day 1 followed by a 21 day wash-out period (time from sirolimus dosing to isavuconazole dosing). On Days 22 and 23, isavuconazole will be dosed three times daily (TID). On Days 24 through 34, isavuconazole will be administered once daily (QD). All subjects will be administered a single dose of sirolimus on Day 26.

Inclusion Criteria:

• The subject has a body weight of at least 45 kg and has a body mass index (BMI) of 18 to 32 kg/m2, inclusive
• Results for aspartate aminotransferase (AST) and alanine aminotransferase (ALT) must be within the normal range
• The female subject agrees to sexual abstinence, or is surgically sterile, postmenopausal (defined as at least 2 years without menses), or using a medically acceptable double barrier method (e.g. spermicide and diaphragm, or spermicide and condom) to prevent pregnancy and agrees to continue using this method from Screening until 3 weeks after the follow-up visit at the end of the study; and is not lactating or pregnant as documented by negative pregnancy tests
• The male subject agrees to sexual abstinence, is surgically sterile, or is using a medically acceptable method to prevent pregnancy and agrees to continue using this method from Screening until 3 weeks after the follow-up visit at the end of the study

Exclusion Criteria:

• The subject has a history of unexplained syncope, cardiac arrest, unexplained cardiac arrhythmia or torsade de pointes, structural heart disease, or family history of Long QT syndrome (suggested by sudden death of a close relative at a young age due to possible or probable cardiac causes)
• The subject has a history of tuberculosis or exposure to anyone known or suspected to have tuberculosis or any illness that, in the opinion of the investigator, might confound the results of the study or pose additional risk in administering study drug to the subject
• The subject has a positive result for hepatitis C antibodies, hepatitis B surface antigen, or QuantiFERON®-TB Gold test or is known to be positive for human immunodeficiency virus (HIV).
• The subject has a known or suspected allergy to any of the components of the trial products including prednisone or the azole class of compounds, or a history of multiple and/or severe allergies to drugs or foods, or a history of severe anaphylactic reactions
• The subject is a smoker (any use of tobacco or nicotine containing products) within 6 months prior to Screening
• The subject has had treatment with prescription drugs or complementary and alternative medicines within 14 days prior to Day -1, or over-the-counter medications within 1 week prior to Day -1, with the exception of acetaminophen up to 2 g/day
• The subject has a recent history (within the last 2 years) of drug or alcohol abuse, or a positive drug and/or alcohol screen