Morphologic Alterations Precede Functional Hepatic Impairment as Determined by 13C-Methacetin Liver Function Breath Test in Adult Fontan Patients

Objectives: Fontan-associated liver disease (FALD) is the most common end-organ dysfunction affecting up to 70–80% of the Fontan population. The clinical significance of FALD is incompletely understood and no unambiguous correlation between hepatic function and FALD severity has been established. In this study, we sought to evaluate maximal liver function capacity with liver maximum function capacity test (LiMAx®) in adult Fontan patients.Methods: Thirty-nine adult Fontan patients (median age: 29.4 years [IQR 23.4; 37.4], median follow-up after Fontan operation: 23.9 years [IQR 17.8;26.4]) were analyzed in a cross-sectional observational study using LiMAx® test (Humedics GmbH, Berlin, Germany), laboratory testing, transient elastography (TE) and hepatic ultrasound. The LiMAx® test is based on the metabolism of 13C-methacetin, which is administered intravenously and cleaved by the hepatic cytochrome P4501A2 to paracetamol and 13CO2, which is measured in exhaled air and correlates with maximal liver function capacity.Results: Maximal liver function capacity assessed by LiMAx® test was normal in 28 patients (>315 μg/h*kg) and mildly to moderately impaired in 11 patients (140–314 μg/h*kg), while no patient displayed severe hepatic impairment (<139 μg/kg*h). No correlation was found between maximal liver function capacity and hepatic stiffness by TE (r2 = −0.151; p = 0.388) or the presence of sonographic abnormalities associated with FALD (r2 = −0.204, p = 0.24). There was, however, an association between maximal liver function capacity and the laboratory parameters bilirubin (r2 = −0.333, p = 0.009) and γ-glutamyl transferase (r2 = −0.367; p = 0.021). No correlation was detected between maximal liver function capacity and the severity of FALD (r2 = −0.235; p = 0.152).Conclusion: To the best of our knowledge, this is the first study to evaluate maximal liver function capacity using LiMAx® test in Fontan patients, which is a useful complementary diagnostic instrument to assess chronic hepatic injury. Maximal liver function capacity was preserved in most of our adult Fontan patients despite morphologic evidence of FALD. Moreover, maximal liver function capacity does not correlate with the extent of FALD severity evaluated by sonography or laboratory analysis. Thus, the development and progression of FALD in Fontan patients is not a uniform process and diagnostics of chronic hepatic injury during follow-up should encompass various modalities.

982. Effect of Hepatic Impairment on the Safety and Pharmacokinetics of Rezafungin

Background Rezafungin (RZF) is a novel echinocandin antifungal being developed for treatment of candidemia and invasive candidiasis, and for prevention of invasive fungal diseases among immunosuppressed patients. In the Phase 2 and Phase 3 treatment trials of rezafungin compared with caspofungin (STRIVE [NCT02734862] and ReSTORE [NCT03667690], respectively), patients with severe hepatic impairment (HI) were not included due to lack of caspofungin data in this population. Rezafungin was previously evaluated in patients with moderate hepatic impairment. Here we report an open-label, single-dose study on rezafungin in patients with HI (Child-Pugh class C). Methods To investigate the safety, tolerability, and pharmacokinetics (PK) of RZF in subjects with HI and healthy subjects (HS), 8 subjects with HI and 8 HS matched for age, sex, and body mass index (BMI) were enrolled and received a single 400-mg intravenous 1-hour infusion of RZF. Plasma PK sampling was performed at various time points through 336 hours postdose. RZF PK parameters were derived using non-compartmental analysis. Safety was assessed throughout the study. Results The majority of the HI subjects were White (87.5%) and male (75%) while equal distribution between White and Black or African American was observed among HS (50%) and 75% were male. The mean age of HI subjects was 58 years (range, 41–68 years) and 56.6 years (range, 50–61 years) for the HS. Mean BMI was 29.7 kg/m2 (range, 24.5–34.3 kg/m2) for HI subjects and 29.7 kg/m2 (range, 25.4–34.2 kg/m2) for the HS. RZF exposure (Cmax and AUC) in subjects with HI was ~30% lower than that in HS (Table 1), while half-life was generally similar (HI: 121 h, HS:124 h; Figure 1). Three HI subjects had one adverse event (AE) each (bronchitis, worsening hepatic encephalopathy, hyponatremia), all moderate in severity; one HS had 1 AE of infusion site infiltration mild in severity. No AEs were considered related to RZF, and all were resolved or resolving by the end of the study. Table 1. Plasma Rezafungin PK Parameter Estimates in Subjects with Severe Hepatic Impairment or Normal Hepatic Function After a Single 400 mg IV Infusion of Rezafungin Figure 1. Mean (+SD) Plasma Rezafungin Concentration-Time Profiles in Subjects with Severe Hepatic Impairment or Normal Hepatic Function After a Single 400-mg IV Infusion of Rezafungin (Semi-Logarithmic Scale) Conclusion RZF was well tolerated in HI subjects and showed modestly reduced exposure that was within the range observed in matched HS. These findings support no RZF dose adjustment in subjects with severe hepatic impairment. Disclosures Voon Ong, PhD, Cidara Therapeutics (Employee, Shareholder) Taylor Sandison, MD, MPH, Cidara Therapeutics (Employee, Shareholder) Rebeca M. Melara, M.S., Altasciences (contract research organization) (Employee) Thomas C. Marbury, MD, Orlando Clinical Research Center (Employee, Other Financial or Material Support, Equity owner of Orlando Clinical Research Center) Alena Jandourek, MD, Cidara therapeutics (Consultant) Shawn Flanagan, PhD, Cidara Therapeutics (Employee, Shareholder)