Efficacy of re-treatment with TMC435 as combination therapy in hepatitis C virus-infected patients following TMC435 monotherapy.

In the TMC435-C101 study, 6 patients infected with hepatitis C virus genotype 1 were treated with the protease inhibitor TMC435 (200 mg once daily) as monotherapy for 5 days. Approximately 1.5 years later, 5 of these patients were re-treated with TMC435 (200 mg once daily) plus pegylated interferon alfa-2a and ribavirin (PegIFNα-2a and RBV) for 4 weeks, followed by PegIFNα-2a and RBV until week 48 (in the Optimal Protease inhibitor Enhancement of Response to therApy [OPERA-1] study). TMC435-resistant variants, which emerged in all 5 patients during the TMC435-C101 study, were no longer detected at the beginning of the OPERA-1 study based on virus population sequencing. During the OPERA-1 study, 3 patients had a sustained virologic response; deep sequencing indicated low-level persistence of resistant variants in the remaining 2 patients, which might have affected their response to re-treatment.