Nearly half of all patients fail current therapy of pegylated interferon with ribavirin.  A patient’s response depends upon the amount and strain of virus, with the genotype 1 strain as the most difficult to treat.  Unfortunately, 75% of the 2.7 million HCV carriers in the United States are infected with the genotype 1 strain and only approximately 40% of these patients respond to current therapy.  Once a patient fails therapy, re-treatment with current therapy (pegylated interferon alpha plus ribavirin) is only effective for 17% of non-responder patients able to tolerate a full dose of pegylated interferon alpha (80% to 100% of the recommended dose).

The market for HCV therapeutics is expected to grow significantly over the course of the next several years as new patients pursue initial therapy and non-responder patients seek re-treatment after failing therapy.