The effect of moderately diminished liver function on the exposure, safety and tolerability of a single dose of FG-4592 is studied in male and female subjects. The results are compared to the data gained from subjects with normal liver function.

The effect of moderate hepatic impairment on the pharmacokinetics (PK), safety and tolerability of a single dose of FG-4592 in male and female subjects is investigated. Data obtained from these subjects are compared to data from BMI-, age- and sex-matched subjects with normal hepatic function. Both groups consist of 8 subjects.

Screening takes place from Days -22 to -2 before admission to the clinical unit on Day -1. Administration of the trial medication takes place on Day 1 under fasted conditions. Healthy subjects are discharged on Day 5 and subjects with moderate hepatic impairment on Day 7, if there is no reason to extend the stay. An end-of-study visit (ESV) takes place 5 to 9 days after (early) discharge.

Safety assessments are performed throughout the study.

Inclusion Criteria:

Both healthy subjects and subjects with moderate hepatic impairment:

• Independent Ethics Committee (IEC)-approved written Informed Consent and privacy language as per national regulations must be obtained from the subject prior to any study-related procedures (including withdrawal of prohibited medication, if applicable).
• Male subjects and their female spouse/partners who are of childbearing potential must be using highly effective contraception consisting of 2 forms of birth control (1 of which must be a barrier method) starting at screening and continuing throughout the study period and for 90 days after the study drug administration.

In addition, subjects with moderate hepatic impairment must also meet the following inclusion criteria:

• Subject has Child-Pugh classification Class B (moderate, 7 to 9 points) liver function impairment [screening].

Exclusion Criteria:

Both healthy subjects and subjects with moderate hepatic impairment:

• Female subject who has been pregnant within 6 months prior to screening or breastfeeding within 3 months before screening.
• Subject has a known or suspected hypersensitivity to FG-4592, or any components of the formulation used.

In addition, healthy subjects must also NOT meet the following exclusion criteria:

• Subject has any of the liver function tests (LFT) (Aspartate Aminotransferase [AST], Alanine Aminotransferase [ALT], Alkaline Phosphatase [ALP], Gamma Glutamyl Transferase [GGT], Total Bilirubin [TBL] above the upper limit of normal (ULN). In such a case the assessment may be repeated once [Day-1].

In addition, subjects with moderate hepatic impairment must also NOT meet the following exclusion criteria:

• Subject had a previous liver transplantation.