AIM: To evaluate daclatasvir vs telaprevir, each combined with peginterferon alfa-2a/ribavirin(peg IFN/RBV), in treatment-naive hepatitis C virus(HCV) genotype(GT) 1-infected patients.METHODS: In this phase 3, randomized, open-label, noninferiority study, 602 patients were randomly assigned(2:1) to daclatasvir vs telaprevir, stratified by IL28 B rs12979860 host genotype(CC vs non-CC), cirrhosis status(compensated cirrhosis vs no cirrhosis), and HCV GT1 subtype(GT1a vs GT1b). Patients were selected by study inclusion criteria from a total of 793 enrolled patients. Patients received daclatasvir 60 mg once daily or telaprevir 750 mg 3 times daily plus peg IFN/RBV. Daclatasvir recipients received 24 wk of daclatasvir plus peg IFN/RBV; those without an extended rapid virologic response(e RVR; undetectable HCV-RNA at weeks 4 and 12) received an additional 24 wk of peg IFN/RBV. Telaprevir-treated patients received 12 wk of telaprevir plus peg IFN/RBV followed by 12(with e RVR) or 36(no e RVR) wk of peg IFN/RBV. The primary objective was to compare for noninferiority of sustained virologic response rates at posttreatment week 12(SVR12) in GT1b-infected patients. Key secondary objectives were to demonstrate that the rates of anemia(hemoglobin < 10 g/d L) and rashrelated events, through week 12, were lower with daclatasvir + peg IFN/RBV than with telaprevir + peg IFN/RBV among GT1b-infected patients. Resistance testing was performed using population-based sequencing of the NS5 A region for all patients at baseline, and for patients with virologic failure or relapse and HCV-RNA ≥ 1000 IU/m L, to investigate any link between NS5 A polymorphisms associated with daclatasvir resistance and virologic outcome. RESULTS: Patient demographics and disease characteristics were generally balanced across treatment arms; however, there was a higher proportion of black/African Americans in the daclatasvir groups(6.0% and 8.2% in the GT1 b and GT1 a groups, respectively) than in the telaprevir groups(2.2% and 3.0%). Among GT1 binfected patients, daclatasvir plus peg IFN/RBV was noninferior to telaprevir plus peg IFN/RBV for SVR12 85%(228/268) vs 81%(109/134); difference, 4.3%(95%CI:-3.3% to 11.9%). Anemia(hemoglobin < 10 g/d L) was significantly less frequent with daclatasvir than with telaprevir difference,-29.1%(95%CI:-38.8% to-19.4%). Rash-related events were also less common with daclatasvir than with telaprevir, but the difference was not statistically significant. In GT1 ainfected patients, SVR12 was 64.9% with daclatasvir and 69.7% with telaprevir. Among both daclatasvir and telaprevir treatment groups, across GT1b- or GT1a-infected patients, lower response rates were observed in patients with IL28 B non-CC and cirrhosis- factors known to affect response to peg IFN/RBV. Consistent with these observations, a multivariate logistic regression analysis in GT1b-infected patients d e m o n s t ra t e d t h a t S V R 1 2 wa s a s s o c i a t e d w i t h IL28 B host genotype(CC vs non-CC, P = 0.011) and cirrhosis status(absent vs present, P = 0.031). NS5 A polymorphisms associated with daclatasvir resistance(at L28, R30, L31, or Y93) were observed in 17.3% of GT1b-infected patients at baseline; such variants did not appear to be absolute predictors of failure since 72.1% of these patients achieved SVR12 compared with 86.9% without these polymorphisms. Among GT1b-infected patients, treatment was completed by 85.4%(229/268) in the daclatasvir group, and by 85.1%(114/134) in the telaprevir group, and among GT1a-infected patients, by 67.2%(90/134) and 69.7%(46/66), respectively. Discontinuations(of all 3 agents) due to an AE were more frequent with telaprevir than with daclatasvir, whereas discontinuations due to lack of efficacy were more frequent with daclatasvir, due, in part, to differences in futility criteria. CONCLUSION: Daclatasvir plus peg IFN/RBV demonstrated noninferiority to telaprevir plus peg IFN/RBV for SVR12 and was well-tolerated in treatment-naive GT1 binfected patients, supporting the use of daclatasvir with other direct-acting antivirals.