412. Etravirine resistance among patients failing on non-nucleoside reverse transcriptase inhibitors: comparison of two genotype algorithms
Session: Poster Abstract Session: HIV - Antiretroviral Therapy
Friday, October 21, 2011
Room: Poster Hall B1
Background: Non-nucleoside reverse transcriptase inhibitors (NNRTIs) are widely used and one of the main concerns is the development of cross-resistance among this class of drug. Etravirine (ETV) was incorporated in the public Brazilian health system, in 2010. Few data are available on NNRTIs cross-resistance profile, considering inter algorithm discordances. The study aims to describe and analyze the expected activity of ETV in clinical samples from patients falling NNRTIs, using two genotype algorithms.

Methods: Samples from 474 patients, experiencing antiretroviral therapy failure, in Goias State-Brazil, were collected and processed according to the National Brazilian Genotyping Network, between 2006 and 2009. TCD4 count, HIV-1 viral load quantification, viral subtype and mutation profile assessment (TRUGENE HIV-1 Genotyping Test e ViroSeq System) were done according to the routine of The Central State Laboratory- Brazil. Resistance mutation profiles were identified using the Brazilian Algorithm (October, 2009) and the Stanford Database Program (April, 2010). Descriptive and exploratory analyses were performed for socio-demographics variables and laboratory results (SPSS 15.0).

Results: Blood samples from 126 patients revealed resistance to NVP and EVF. Subtype B represented 86.1% and BF1 recombinant 7.8% of the samples. Half of the patients received three or more antiretroviral therapy regimes pre-genotyping. The most frequent mutations were 103N (72.2%) and 225H (22.2%). Mutations related to decrease ETV activity were detected in 8 codons: 98, 100, 101, 181, 188, 190 and 230. High degree of resistance to ETV was detected in 2.4% (IC95% 0.5-6.8) of the samples, according to Stanford algorithm. Resistance to ETV was identified in 7.9% (IC95% 3.9-14.1), according to the Brazilian protocol. Clinical characteristics, number of TCD4 cells nor viral load were associated with ETV resistance.

Conclusion: The presence of at least one mutation potentially associated with decreased virological response to ETV was frequent, in a population highly exposed to NNRTIs. Otherwise high-degree of cross resistance to ETV was not common, suggesting that this drug could be helpful for patients failing to 1st generation NNRTIs.

Subject Category: H. HIV/AIDS and other retroviruses

Priscila Ribeiro Pacheco, MD, Tropical Diseases Hospital - Health State Department -Goias, Goiania, Brazil, Luis Carlos Sousa, MD, Federal University Goias and Tropical Diseases Hospital, Goiania, Brazil, Boaventura Braz Queiroz, MD, Tropical Diseases Hospital - Health State Departament Goias, Goaiania, Brazil and Marilia Turchi, MD, PhD, Institute of Tropical Pathology and Public Health, Federal University Goias, Goiania, Brazil


P. R. Pacheco, None

L. C. Sousa, None

B. B. Queiroz, None

M. Turchi, None

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