Genotypic resistance to darunavir, tipranavir and etravirine in patients with failure to two or more ARV combinations in Mexico
E. Vidal-Laurencio1, L. Cabrera-Ruiz2, A. Flores-Gaxiola2, J. Gaytan2, I. Torres2, L.E. Soto-Ramirez2
1Instituto Nacional de Ciencias Médicas y Nutrición Salvador Zubirán, Infectious Diseases, Mexico City, Mexico, 2Instituto Nacional de Ciencias Medicas y Nutricion Salvador Zubiran, Unidad de Virología Molecular, Mexico D.F., Mexico
Background: Despite universal access to ARV treatment Mexico, most of the time failures are assessed late and with no resistance assays.Through an online program, we provided resistance assays as well as expert advice to treating physicians. These are the results of the first year of the program, focused on the genotypic resistance to Darunavir (DRV), Tipranavir(DRV) and Etravirine(ETV).
Methods: Patients were included if they had failure to two or more ARV combinations, and no previous use of DRV, TPV or ETV. Their physicians filled an online form to evaluate each case. Genotypic results were analyzed by four experts who established a recommendation for the salvage treatment. For the purpose of this analysis we evaluate resistance using the Standford Database (high level resistance) as well as genotypic scores generated by Johnson & Johnson, and Boehringer-Ingelheim.
Results: We evaluate a total of 348 cases. Of those cases 252(72.4/%) had resistance to one or more ARV drugs, 61(17.5%) had no resistance, and 27(7.8%) were non-amplifiable. Of the 252 cases with mutations, resistance to NNRTIs was found in 177(70.2%), most of them without actual treatment with drugs of this group. In 17/177(9.6%) resistance to Etravirine was found, with 53% having history of NVP use, 17.6% of EFV and 23.5% of both. Fifteen cases(5.7%) had resistance to DRV and 21(8.3%) to TPV, with an average use of 3 previous PIs(1-5). The most common combination recommended for salvage treatment was TDF+DVR/r+Raltegravir in 80 cases(30.7%).
Conclusions: Accumulated resistance in Mexican patients with multidrug ARV failure is high. Etravirine resistance is high (and probably higher as no actual use of NNRTIs and loss of some mutations could happen), probably due to excessive use of NVP and late failures. Darunavir resistance is still low, however has increased almost 5 times since 2007(1.2%), while TPV resistance has not changed.
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