Disclosures: Maria Prins – Speaking and Teaching: msd, roche Tim Beaumont – Employment: Caspase activation AIMM Therapeutics Richard Molenkamp – Independent Contractor: Roche Diagnostics The following people have nothing to disclose: Xiomara V. Thomas, Sylvie M. Koekkoek, Jan T. van der Meer,

Sabrina Merat, Janke Schinkel Background. The confirmation of serum HCV-RNA undetectability in several critical points during treatment (weeks 4,and 24) is crucial for monitoring antiviral response in patients with chronic hepatitis C (CHC) treated with peglFN + Ribavirin + Telaprevir. However, there are few data on the kinetic of HCV-RNA negativization in peripheral blood mononuclear cells (PBMCs), an extrahepatic HCV infection target of unclear clinical significance. Aim. To compare the kinetic of HCV-RNA negativization in plasma and PBMCs of patients with CHC under telaprevir-based triple therapy. Patients.

We included 15 Caucasian patients FDA-approved Drug Library solubility dmso (4 naīve, 8 relapsers, 2 partial responders and 1 null responder to previous dual PeglFN+Ribavirin treatment) who completed the treatment period with triple therapy. Eight (53%) completed the follow-up period. Serum HCV-RNA titers were tested according the treatment protocol. HCV-RNA in PBMCs was tested using an in house RT-nested PCR with a ĪaqMan probe at 0, 4, and 12 weeks after treatment in all patients and at the end of treatment in 6 patients. Results. Extended rapid virological response (eRVR) was achieved in 11/15 (73%) patients and serum HCV-RNA became negative at week 12 in 3 (20%) aditional patients. Only one patient discontinued the treatment due to an HCVRNA titer of 1687 IU/ml at week 4 (stopping 上海皓元 rule). No breakthrough

was observed and 14 (93%) patients were HCV-RNA negative at the end of treatment. In addition, all 8 patients with follow-up achieved SVR24. In PBMCs HCV RNA was detected in 11/15 (73%) patients at baseline, in 7/15 (47%) at week 4, in 4/14 (28%) at week 12 and in 1/6 (16%) at week 24 (12 weeks after serum HCV-RNA negativization). Persistence of HCV-RNA in PBMCs was significantly higher in patients without eRVR than in responders (positivity at week 4: 4/4(100) vs 3/11 (27%); p=0.02). There was no differences among patients with and without eRVR in the IL28B polymorphisms, baseline HCV-RNA and/or HCV-1 subtypes Conclusions: HCVRNA levels decrease sharply in PBMCs during telaprevir-based therapy but with a slower kinetic than that observed in plasma. The persistence of viral sequences in PBMCs is associated with the lack of eRVR. Disclosures: Javier Garda-Samaniego – Consulting: Boehringer-Ingelheim The following people have nothing to disclose: Antonio Madejon, Miriam Romero, Araceli G.