15th International AIDS Conference Bangkok, Thailand - July 11-16, 2004

Int Conf AIDS 2004 Jul 11-16; 15:(abstract no. WeOrB1293)

Lafeuillade A, Hittinger G, Delbeke E, Poggi C
General Hospital, Toulon, France

BACKGROUND: HIV-1 resistance testing is not usually recommended with low viremia levels. We assessed genotypic resistance evolution in patients on a maintained antiretroviral regimen despite detectable viremia between 50 and 1000 copies/ml.

METHODS: Selected cases from a series of 1200 HIV-1-infected patients had 2 genotypic tests while maintaining the same antiretroviral regimen. Plasma HIV-1 RNA was measured by using the Roche Amplicor Monitor kit; RT and PR gene sequencing was performed by using a an ABI Prism 310 analyser.

RESULTS: 22 patients of average age 40 years fulfilled these criteria. Median duration of HIV-1 infection was 102 months (48-180); median time from first antiretroviral regimen was 48 months (36-84). Eleven cases were on first line therapy, 7 cases on second line and 4 cases on third line. Median time between the 2 genotypic tests was 28 months (8-48). During this interval, 10 cases were on a 3 NRTI regimen, 4 cases on 2 NRTIs plus 1 nNRTI, and 8 cases on 2 NRTIs plus 1 PI. At the time of the first genotypic test, median CD4 cell count was 555/mul (278-969) and median viremia was 240 copies/ml (55-1000). No changes in genotypic patterns were found in 7 cases although 15 cases selected new resistance mutations in the RT and/or PR genes (RT: 65R: 4 cases, 67N: 2, 70R: 3, 69 insert: 1, 74V: 2, 103N: 1, 190A: 1, 184V: 7, 215Y: 1, 219Q: 1; PR: 30N: 1, 36I: 2, 88D: 1, 90: 1 case). 64% of patients overall selected RT mutations, and 43% of patients on a PI-containing regimen selected PI mutations. At the time of the second test, median CD4 count and viremia (607/mul and 264 c/ml) were no significantly different even when patients selecting new mutations only were considered. Conclusion Despite stable viremia and CD4 counts, resistance continued to develop in most patients on maintained regimens over a median period of 28 months. This may have a negative impact on future antiretroviral options and favors early switching from sub-optimal regimens.

040711
WeOrB1293

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