Treatment was stopped in patients with detectable HCV RNA at week 24 (nonresponders). Patients with undetectable HCV RNA at the end of the planned course of treatment (end-of-treatment [EoT] responders) were followed up for 24 weeks. SVR was defined as undetectable HCV RNA (50 IU/mL) at end of follow-up.

Conversely, virologic relapse was defined as detection of HCV RNA (≥50 IU/mL) at the end of follow-up in Selleckchem Ganetespib a patient with an EoT virologic response. Quantitative serum HCV RNA tests were done with the COBAS AMPLICOR HCV Monitor Test, v. 2.0 (limit of quantification 600 IU/mL). Qualitative tests were done with the COBAS AMPLICOR HCV Test, v. 2.0 (limit of detection 50 IU/mL). Samples with undetectable HCV RNA by the qualitative test were retested with the more sensitive Roche TaqMan assay (limit of detection 10 IU/mL). Whole blood samples obtained and stored in ethylene diamine tetraacetic acid (EDTA)-containing collection tubes were used for IL28B genotype testing. DNA was subsequently isolated and the rs12979860 SNP in the region of the IL28B gene was analyzed by the StepOnePlus Real-Time PCR System (Applied Biosystems, Foster City, CA) with a custom TaqMan SNP Genotyping Assay developed in collaboration with Applied Biosystems as described.23 Gene sequences were obtained from the NCBI Entrez

SNP Database (http://www.ncbi.nlm. nih.gov/sites/entrez). GCCTGTCGTGTACTGAACCA was used as the forward and GCGCGGAGTGCAAT TCAA as the reverse primer in the genotyping medchemexpress assay for rs12979860. All statistical calculations were LEE011 manufacturer done with SigmaPlot v. 11 (Systat Software, Erkrath, Germany). Treatment outcome (SVR or relapse) was analyzed by χ2

test in the various treatment groups by IL28B genotype (C/C versus T/C or T/T). Only patients who completed treatment as per protocol and with known EoT and end-of-follow-up (SVR or relapse) results were included in the analysis of relapse and SVR. This ensured that the analysis of outcome by treatment duration was not confounded by the inclusion of patients who withdrew prematurely and received less than the planned duration of treatment. All patients included in this analysis provided informed written consent to rs12979860 genotype testing. The IL28B rs12979860 polymorphism was determined for 340 of 551 (61.7%) study participants overall. Across the four treatment groups the proportion of patients represented in the rs12979860 genotype analysis ranged from 60% to 67% of the original intention-to-treat (ITT) population (Fig. 1). The overall rs12979860 genotype frequency was C/C: 115 (33.8%), T/C: 175 (51.5%), and T/T: 50 (14.7%). The baseline characteristics of these patients are shown in Table 1 and the rs12979860 genotype frequencies are presented by treatment group in Fig. 2.