December 23, 2010
In the Extend study, researchers enrolled volunteers from several previous studies of telaprevir into a multinational three-year study to evaluate the following issues:
In previous trials researchers detected HCV that was resistant to telaprevir in participants who did not achieve an SVR, specifically in the HCV NS3 protease gene. So research on HCV drug resistance is important in helping researchers understand how best to use telaprevir and other emerging therapies.
Participants in Extend were assessed at the start of the study (baseline) and six months later, and thereafter, once yearly for up to three years in some cases. For the interim analysis reported here, researchers focused on 123 participants who achieved an SVR and 79 others who did not.
After an average of two years in Extend, researchers found that SVRs were durable, with 122 out of 123 people (99.2%) continuing to have undetectable HCV. The lower limit of quantification of the assay used was 25 IU/ml.
Among participants with an SVR, no major clinical events occurred.
Among 79 participants who did not have an SVR, 56 had blood samples available for analysis. Here are some of the complications that ensued among participants without an SVR:
Initially, various mutations in the HCV protease gene (NS3) were detected in 7% to 45% of people (depending on the mutation). However, after about two years of monitoring, resistant virus could not be found in about 90% of participants.
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