Successful prevention of transmission of integrase resistance in the Swiss HIV Cohort Study. Journal of Infectious Diseases
Scherrer et al. aimed to analyze the prevalence of transmitted integrase strand transfer inhibitor (INSTI) resistance in the Swiss HIV Cohort Study (SHCS) and to identify risk factors for its occurrence. Only 1 major mutation (T66I) was found (1 of 1316 [0.1%]) in a sample retrieved in 2001. In 38 of 1316 samples (2.9%), viruses were found with minor INSTI resistance mutations. Minor mutations were significantly more common in subtype non-B infections as compared to subtype B infections. There was no evidence for an increase in prevalence of minor mutations in the years after the introduction of INSTIs. The study demonstrates on a population-level that it is possible to avoid transmitted drug resistance to a new drug class for years.
Commentary Dominique Braun (MD) and Huldrych Günthard (MD)
The Swiss setting cannot be compared to other settings with limited access to viral load monitoring or no available second-line and third-line therapies. In these settings, patients may continue to receive failing regimens and may accumulate more drug resistance mutations. Of particular importance will be to investigate the effect of decreasing monitoring frequency that is proposed and performed in some countries. This may lead to delayed detection of treatment failures with subsequent emergence of resistance and a higher population viral load of nonresponding patients.