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

Disclosures:

P. R. Pacheco, None

L. C. Sousa, None

B. B. Queiroz, None

M. Turchi, None

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