Background Hepatitis C virus (HCV) is the most common cause of mixed cryoglobulinemia syndrome (MCS). The efficacy and safety of all-oral directly-acting antiviral (DAA) therapy in HCV-associated MCS (HCV-MCS) is largely unknown. Methods Case series of patients with HCV-MCS who were treated with sofosbuvir-based regimens and historical controls treated with pegylated interferon and ribavirin in a single healthcare network. HCV-MCS was defined by circulating cryoglobulin associated with systemic vasculitis symptoms. Renal involvement (N=7) was established by kidney biopsy (N=5) or by ≥ 2 of the following clinical findings: reduced kidney function, proteinuria, or hematuria with other causes excluded (N=2). Results Twelve patients received DAA therapy between December 2013 and September 2014. Median age was 61 years, 58% male, 50% had cirrhosis. Median baseline serum creatinine was 0.97 mg/dL (range 0.7 – 2.47 mg/dL.) Four patients received Rituximab concurrent with DAA therapy. Sustained virological response rate at twelve weeks (SVR12) was 83% overall. Patients with glomerulonephritis who achieved SVR12 experienced an improvement in serum creatinine and reduction in proteinuria. Cryoglobulin levels decreased in 89% of patients, with median percent decreasing from 1.5% to 0.5%, and completely disappearing in 4 of 9 cases who had cryoglobulins measured after treatment. Serious adverse events were infrequent (17%). In contrast, the historical cohort treated with pegylated interferon and ribavirin experienced only 10% SVR12 rate with 100% experiencing at least one adverse event, and 50% experiencing premature discontinuation due to adverse events. Conclusion SVR12 rates for sofosbuvir-based direct acting antiviral regimens in HCV-MCS were 83%, significantly higher than historical controls treated with pegylated interferon and ribavirin. Patients with glomerulonephritis experienced improvement in renal function, including those not concomitantly treated with immunosuppression.

Patients with chronic hepatitis C and low serum and hepatic iron stores may have an improved response to interferon (IFN). We tested whether iron reduction before and during IFN therapy would lead to an improved sustained biochemical and virological response compared with IFN alone. Eighty-two previously untreated patients with chronic hepatitis C were randomized to either: group A IFN-␣2b 3 MU 3 times per week for 6 months, or group B iron reduction before and during IFN-␣2b 3 MU 3 times per week for 6 months. Group B patients had lower mean serum alanine transaminase (ALT) levels than group A patients during treatment and follow-up. Group B patients had significantly lower mean hepatitis C virus (HCV)-RNA levels at treatment weeks 4 and 12 (P F .05). Serum HCV RNA was undetectable at the end of treatment in 15 group B patients compared with 7 group A patients (P ‫؍‬ .03); 7 group B patients and 3 group A patients had persistently undetectable serum HCV RNA 24 weeks after the end of therapy (P ‫؍‬ .

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Treatment of recurrent HCV infection with combination of IFN or PEG-IFN and RBV produced an on-therapy VR in 29% and BR in 65% of patients. Hematologic toxicity and dose modifications were frequent. Our experience with antiviral therapy for HCV post-OLT remains disappointing but PEG-IFN + RBV appears to produce VR in a sizable portion of IFN + RBV non-responders.