The primary purpose of this open-label study is to characterize the plasma pharmacokinetics (PK) of manogepix (active moiety of fosmanogepix) in participants with varying degrees of hepatic function following administration of a single oral dose of fosmanogepix.

All participants will receive 1 dose of fosmanogepix by mouth before breakfast on the first day at the study clinic. Serial blood samples will be collected to understand how fosmanogepix is changed and eliminated from the body. Participants will also receive physical examination and other tests. This will help to understand if fosmanogepix is safe.

Participants will be involved in this study for 4 to 9 weeks (maximum). There will be 2 to 4 study visits at the study clinic.

Key Inclusion Criteria:

• Body mass index (BMI) of 17.5 to 40.0 kg/m2 (42 kg/m2 for participants of Cohort 3), inclusive; and a total body weight greater than 50 kg (greater than 110 lb)
• For participants with hepatic impairment (Cohorts 1-3, and Cohort 5): Stable hepatic impairment that meets the criteria for Class A, B, or C of the Child Pugh classification with no clinically significant change in disease status within the 28 days prior to the screening visit
• For participants with normal hepatic function (Cohort 4): 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
• Stable concomitant medications for the management of individual participants' medical history

Key Exclusion Criteria:

• Any condition possibly affecting drug absorption (eg, prior bariatric surgery, gastrectomy, ileal resection);
• Ongoing medical history of neurological disorders including abnormal movements or seizures (Note exception: stable history of peripheral neuropathy);
• Hepatic carcinoma or hepatorenal syndrome or limited predicted life expectancy;
• A diagnosis of hepatic dysfunction secondary to any acute ongoing hepatocellular process that is documented by medical history, physical examination, liver biopsy, hepatic ultrasound, computerized tomography scan, or MRI;
• Signs of clinically active Grade 2, 3 or 4 hepatic encephalopathy (ie, equal or greater than Grade 2 Portal Systemic Encephalopathy score)