[Telaprevir resistance].

Telaprevir is an extremely potent antiviral drug. However, as with other direct-acting antiviral agents against the hepatitis C virus (HCV), this potency can be compromised by the rapid emergence of resistance mutations. This phenomenon is favored by the high rate of HCV replication, the lack of corrective activity to HCV polymerase errors, a low genetic barrier to resistance, and poor treatment adherence. Like other HCV protease inhibitors, telaprevir has a low genetic barrier to resistance. Phase II/III clinical trials (ADVANCE, ILLUMINATE and REALIZE) have characterized resistance to telaprevir in combination with pegylated interferon and ribavirin both genotypically and phenotypically. Mutations are selected mainly in positions 36, 54, 55, 155 and 156. The resistance profile depends on the genetic subtype of HCV, with selection of mutations in positions 36 and 155 for subtype 1a and in positions 36, 54, 55 and 156 for subtype 1b. The V36M+R155K and A156F/T/V variants confer a high degree of resistance (>25-fold increase), while the impact on resistance of other mutations such as V36A/G/M, T54A/S, R155G/K/M/T and A156S is lower (3-25- fold increase). The presence of polymorphisms or mutations associated with telaprevir resistance is very low (< 1%), especially for mutations with a higher impact on resistance. There is a high degree of cross resistance among protease inhibitors. However, the rapid reversion of telaprevir resistance mutations after the end of treatment could allow the use of "recycling" strategies with protease inhibitors.