A randomized phase 2b study of peginterferon lambda-1a for the treatment of chronic HCV infection.

BACKGROUND & AIMS Peginterferon lambda-1a (Lambda) is a type-III interferon with similar antiviral activity to alfa interferons but with a diminished extrahepatic receptor distribution, reducing the risk for extrahepatic adverse events. METHODS This was a randomized, blinded, actively-controlled, multicentre phase 2b dose-ranging study in patients chronically infected with HCV genotypes 1-4. Treatment-naive patients received Lambda (120/180/240 μg) or peginterferon alfa-2a (alfa; 180 μg) once-weekly with ribavirin for 24 (genotypes [GT] 2,3) or 48 (GT1,4) weeks. RESULTS Rates of undetectable HCV-RNA at week 12 (complete early virologic response [cEVR]; primary end point) were significantly higher in GT1,4 patients receiving Lambda vs. alfa (170/304, 56% vs. 38/103, 37%); with similar cEVR rates for GT2,3 (80/88, 91% vs. 26/30, 87%). Rates of undetectable HCV-RNA at week 4 were significantly higher on 180 μg (15/102, 15% GT1,4; 22/29, 76% GT2,3) and 240 μg (17/104, 16% GT1,4; 20/30, 67% GT2,3) Lambda than alfa (6/103, 6% GT1,4; 9/30, 30% GT2,3). Sustained virologic responses (post-treatment week 24) were comparable between Lambda and alfa for GT1,4 (37-46% Lambda; 37% alfa) and GT2,3 (60-76% Lambda; 53% alfa). Aminotransferase and/or bilirubin elevations were the primary dose-limiting abnormalities for Lambda; a sponsor-mandated 240 to 180 μg dose reduction was therefore implemented. Serious adverse events were comparable (3-13% Lambda; 3-7% alfa). Grade 3-4 haemoglobin, neutrophil, and platelet reductions were lower on Lambda than alfa. Among alfa patients, 28/133 (21%) had peginterferon and 31/133 (23%) had ribavirin dose reductions for haematologic abnormalities vs. 0/392 and 8/392 (2%) on Lambda. Lambda demonstrated fewer musculoskeletal (16-28% vs. 47-63%) and influenza-like events (8-23% vs. 40-46%) than alfa. CONCLUSION Lambda was associated with improved or similar rates of virologic response with fewer extrahepatic adverse events than alfa in chronic HCV infection.