Changes in renal function indices in cirrhotic chronic hepatitis C patients treated with sofosbuvir-containing regimens

This study aimed to explore changes in hepatic and renal function indices in chronic hepatitis C (CHC) patients treated with direct-acting antivirals (DAAs). Forty-three CHC patients treated with sofosbuvir (SOF)-containing regimens were enrolled. At the end of treatment, the estimated glomerular filtration rate (eGFR) level was significantly decreased and the serum creatinine (Scr) and uric acid (UA) levels were significantly increased compared with baseline levels (eGFR: 86.7 ± 20.4 vs 80.5 ± 21.3, P01 = 0.005; Scr: 83.9 ± 19.1 vs 89.6 ± 21.1, P01 < 0.001; UA: 323.7± 86.2 vs 358.5 ± 93.2, P01 < 0.001); no significant improvements were observed at 24 w post-treatment (eGFR: 86.7 ± 20.4 vs 81.4 ± 18.6, P02 = 0.013; Scr: 83.6 ± 17.9 vs 87.9 ± 18.3, P02 = 0.014; UA: 320.8 ± 76.3 vs 349.3 ± 91.0, P02 = 0.004). When the patients were grouped by liver conditions, non-cirrhotic patients and cirrhotic patients had decreased eGFR levels and increased Scr levels at the end of treatment; at 24 w post-treatment, the eGFR and Scr levels were significantly improved in non-cirrhotic patients (88.4 ± 21.7 vs 83.8 ± 18.5, P02 = 0.142; 84.4 ± 20.4 vs 87.0 ± 16.9, P02 = 0.088), while no obvious improvements were observed in cirrhotic patients (84.3 ± 18.7 vs 78.1 ± 18.6, P02 = 0.002; 83.2 ± 17.7 vs 89.2 ± 20.6, P02 = 0.006). Clinical physicians should closely monitor renal function in patients treated with SOF-containing regimens, especially in cirrhotic patients.

With the wide application of DAAs, challenging issues regarding the efficacy and safety of new DAAs regimens have arisen, e.g., resistance-associated variants, drug-drug interactions (DDIs), HBV (hepatitis B virus) reactivation, hepatotoxicity and nephrotoxicity [9][10][11][12][13][14][15][16][17][18][19][20]. In October 2016, the United States Food and Drug Administration issued a black box warning regarding the risk for HBV activation with 9 DAAs, citing 24 cases that included 3 reports of acute liver failure (https://www.fda. gov/). The Institute for Safe Medicine Practices followed up with a review of Adverse Event Reporting System data covering a 12-month span. The review uncovered 524 cases of liver failure associated with DAAs and that 31.5% of the patients had died at the time of the review (http://www.ismp.org/ default.asp). Traditional PR treatment regimens and first-generation protease inhibitors are considered nephrotoxic [21,22]. Although all-oral DAAs regimens were well tolerated in clinical trials, recent real-world studies demonstrated some cases with nephrotoxicity that were treated with sofosbuvir Research Paper www.impactjournals.com/oncotarget (SOF)-containing regimens [18][19][20]. Some cases with hepatotoxicity and nephrotoxicity associated with DDIs were reported in CHC patients with concomitant diseases, HBV or HIV co-infections, and liver transplantations [11,14,16,17].
Considering the increasing occurrence of cases with hepatotoxicity, nephrotoxicity, and DDIs, this study aimed to explore the changes of hepatic and renal function indices in CHC patients treated with DAAs.

Changes of hepatic function indices
The mean aminotransferase (ALT) and AST levels at the end of treatment and at 24 w post-treatment were significantly decreased compared with the baseline levels (ALT: 57.8 ± 38.1 vs 19.8 ± 14.2, P 01 < 0.001; 57.8 ± 38.1 vs 17.3 ± 6.8, P 02 <0.001; AST: 53.2 ± 31.8 vs 24.4 ± 9.9, P 01 < 0.001; 53.2 ± 31.8 vs 22.7 ± 6.9, P 02 < 0.001) ( Table 2), whereas one decompensated cirrhotic patient (LSM = 41.2 kPa, mild ascites) treated with SOF/LDV developed a liver injury at the end of treatment (ALT = 101 IU/L; AST = 72 IU/L). A 53-year-old female patient was hospitalized with a persistent low-grade fever, fatigue and sleepiness on January 22nd, 2016. The baseline ALT and AST levels were within the normal ranges and there was neither alcohol use nor concomitant medications during the SOF/LDV treatment. Silymarin capsules (MADAUS GmbH, Germany) were prescribed for two weeks (140 mg/bid), and ALT and AST levels were kept in normal ranges until 24 weeks post-treatment ( Figure 1). Along with the recovery of the liver function, the PLT count at 24 w post-treatment was significantly increased compared with the PLT count at baseline (142.7 ± 66.8 vs 148.8 ± 67.4, P 01 = 0.112; 142.7 ± 66.8 vs 155.7 ± 66.9, P 02 < 0.01) ( Table 2).
Considering the difference in liver conditions and treatment durations, changes in renal function indices were compared between non-cirrhotic patients and cirrhotic patients (Table 3). At the end of treatment, non-cirrhotic patients and cirrhotic patients had decreased eGFR levels and increased Scr levels (non-cirrhotic: 88. 4

DISCUSSION
The availability and rapid development of DAAs has revolutionized the management of CHC and achieved a high SVR rate with a low incidence of AEs. Although DAAs are highly effective and well tolerated, some cases with hepatotoxicity and nephrotoxicity have been reported [14][15][16][17][18][19][20]. Thus, this study analyzed the efficacy of DAAs treatment and the effects on hepatic and renal function indices in CHC patients in clinical practice.
In this study, combined DAA therapy achieved a promising SVR rate (97.7%) that was not significantly different from the rates reported in previous studies [23][24][25][26]. However, the abnormal changes in renal function indices were unexpected. At the end of treatment, the eGFR level was significantly decreased and the Scr and UA levels were significantly increased; at 24 w posttreatment, non-cirrhotic patients showed improvements, whereas a persistent decrease in eGFR level and increases  in Scr and UA levels were observed in cirrhotic patients ( Table 2, Table 3). eGFR and Scr were important indices for assessing renal function, and an elevated UA level also predicted a rapid decline in kidney function [27].
Although the specific mechanisms were unknown, possible reasons for the abnormal changes in renal function indices in this study are as follows: (1) Potential DDIs caused by complicated concomitant medication use might be a major reason for the abnormal changes. Each DAA had its own metabolism and potential DDIs [28]; drug metabolic enzymes, such as cytochrome P450 (CYP450); drug transporters, such as P-glycoprotein (P-gp); and breast cancer resistance protein (BCRP) were the most common pathways leading to DDIs. Unlike in clinical trials, concomitant medications that had potential DDIs with DAAs are frequently prescribed to patients with chronic HCV infection in clinical practice [29,30]. DAAs or concomitant medications could act as substrates, inhibitors and inducers of metabolic enzymes and transporters, leading to an elevated blood drug concentration [31,32]. In this study, two combined DAAs regimens had the same effects on changes in  renal function indices, and we speculated that the SOF use in the two regimens might account for the abnormal changes in renal function indices. SOF is intracellularly metabolized and forms the active metabolite GS-461203 and the inactive compound GS-331007, which is primarily renally excreted; moreover, SOF is a substrate of P-gp and BCRP and is 61-65% bound to plasma proteins [33]. DDIs among SOF, GS-331007 and concomitant medications could cause kidney injury due to increased blood drug concentration, especially when concomitant medications with potential hepatotoxicity and nephrotoxicity are prescribed.
(2) High frequencies of comorbidities and concomitant medications in this elderly patients might also contribute to the abnormal changes in renal function indices. This was a relatively elderly cohort; the mean age was 57.9 ± 15.7 years, with 51.2% of the patients were more than 60 years old, and 41.9% of the patients had cirrhosis (Table 1); 62.7% of the patients were found to have comorbidities and 74.4% of the patients had at least one concomitant medication, including antihypertensives (32.6%), antibiotics (23.3%), antipyretic analgesics (20.9%), statins (14.0%), antidiabetics (11.6%), gastrokinetic agents (11.6%), proton pump inhibitors (9.3%), or hepatoprotectants (9.3%). Recent studies also showed high frequencies of comorbidities and concomitant medications in elderly patients during treatment with DAAs, many of which had potential DDIs with DAAs [34][35][36]. (3) Cirrhotic patients had persistent abnormal changes in renal function indices. Cirrhotic patients received 24 weeks of combined DAA treatment, and prolonged treatment durations increased the risk of DDIs between DAAs and concomitant medications; the cirrhotic patients were older than the non-cirrhotic patients (Table 1), elderly patients had more concomitant medications, which represented high risks for DDIs [34,35] and eGFR declined with aging by approximately 1 mL/min/1.73 m 2 annually which could result in a decreased renal elimination capacity and increased blood drug concentration of DAAs or concomitant medications [27,37]; studies using a single 400 mg dose of SOF in patients with renal impairment have shown a significant increase in serum levels of SOF and the metabolite GS331007 compared with levels in patients with normal renal function (eGFR > 80 ml/ min/1.73 m 2 ) [33]; cirrhotic patients in this cohorts had relatively lower eGFR levels than non-cirrhotic patients (Table 1), which might result in a decreased renal elimination capacity and the accumulation of SOF and its metabolite GS331007 or concomitant medications; these factors might have jointly contributed to the persistent elevation of Scr and UA levels in cirrhotic patients. One decompensated cirrhotic patient treated with SOF/LDV was found to have elevated ALT and AST levels, and there were no other virus infections, alcohol use, or concomitant medications (Figure 1). Cirrhosis destroyed the structure and function of the liver, reduced the expression of drug metabolizing enzymes and thus reduced metabolizing capacity, which increased the blood concentration of the drugs metabolized by these enzymes [33,38]; this might have led to liver injury in the patient with decompensated cirrhosis.
The abnormal changes observed in renal function indices associated with the SOF-containing regimens in this study should be taken as a note of caution. Clinical physicians should closely monitor hepatic and renal function in patients treated with SOF-containing regimens, especially in cirrhotic patients.

Patients
Forty-three CHC patients who were treated with DAAs while hospitalized in Peking University First Hospital between January 2015 and January 2017 and met the following criteria were enrolled in this study: (1) infected with HCV GT 1b; (2) negative for hepatitis A virus immunoglobulin M (HAV IgM), hepatitis B surface antigen (HBsAg), hepatitis E virus IgM (HEV IgM), human immunodeficiency virus (HIV), Epstein-Barr virus (EBV), and cytomegalovirus (CMV); (3) no severe renal function impairment (eGFR < 30 ml/min/1.73 m 2 ) and end-stage renal disease; (4) no severe heart disease; (5) no active drug use and no alcohol use; (6) no pregnancy; (7) DAAs treatment regimens prescribed according to the recommendation of the new guidelines [39][40][41]; and (8) clinical information is intact. A total of 31 patients were excluded, including 14 HCV GT2a infected patients, one HBV/HCV co-infected patient, one CMV/HCV co-infected patient, 3 patients with severe renal function damage, one patient treated with DAAs regimens who did not comply with the guidelines, and 11 patients with incomplete clinical information. Of the 43 patients, 18 were treated with SOF (400 mg/day) / DAC (60 mg/day) and 25 were treated with SOF (400 mg/day) / LDV (90 mg/ day); non-cirrhotic patients were treated for 12 weeks and cirrhotic patients were treated for 24 weeks. All study participants provided informed written consent prior to enrollment in the study. Ethical approval was given by the Ethics Committee. The study was in compliance with the Helsinki Declaration.

Clinical data collection, HCV RNA quantitation, and genotyping
Hematological, biochemical, and urine tests were performed and recorded at 0 w, 2 w, 4 w, 8 w, 12 w, or 24 w during the DAA treatment, as well as at 4 w, 12 w, and 24 w post-treatment at a clinical laboratory. The virological endpoint was the achievement of SVR 12, and clinical indices at 24 w post-treatment were recorded as clinical endpoints. The ALT, AST and PLT count were used to assess liver function; eGFR, Scr, UA, and BUN were used to assess renal function.