Low Complement C4 Predicts Improvement of Kidney Function After Direct‐Acting Antiviral Therapy for Hepatitis C Virus

Direct‐acting antiviral therapies (DAAs) may improve kidney function and proteinuria in certain patients with hepatitis C infection (HCV) and chronic kidney disease (CKD). To improve our understanding of HCV‐mediated kidney dysfunction, we aimed to evaluate the baseline predictors of improvement in proteinuria after DAAs in a single‐arm, pilot, clinical trial of ledipasvir 90 mg/sofosbuvir 400 mg once daily for patients with HCV genotype 1 or 4 infection and proteinuric CKD (≥300 mg proteinuria per gram creatinine). Plasma biomarkers of complement system (C3 and C4) and urinary kidney injury biomarkers were measured at baseline, 8 weeks on treatment, 12 weeks following treatment, and 1 year following treatment. We then conducted a retrospective cohort study of patients at Partners Healthcare who had baseline complement component 4 (C4) measured before DAAs for HCV and evaluated the change in estimated glomerular filtration rate (eGFR) before and after therapy. Ten patients with HCV and proteinuric CKD were enrolled in the trial. The mean age was 64 years, 70% male, 70% white, and 30% black. Baseline creatinine was 1.25 mg/dL (SD 0.44), eGFR was 65 mL/min/1.73 m(2) (SD 29), and proteinuria was 0.98 g/g creatinine (SD 0.7). Sustained virologic response at 12 weeks was achieved by 80% of patients. Patients with low baseline C4 had improved proteinuria, urinary neutrophil gelatinase‐associated lipocalin, and interleukin‐18 after ledipasvir and sofosbuvir treatment. The retrospective study included 50 patients with CKD and HCV. Twenty patients (40%) had low baseline C4; these patients significantly improved their eGFR (+3.4 ± 11.2 mL/min/1.73 m(2)) compared to those with normal baseline C4 (−4.4 ± 12.2 mL/min/1.73 m(2); P = 0.028). Conclusion: Low C4 may be a marker of kidney dysfunction that improves with DAA therapy.