HIV-salvage therapy guided by genotypic resistance testing and the geno2pheno® interpretation system

Poster number: 25

M Oette 1, M Däumer 2, R Kaiser 2, N Beerenwinkel 3, T Sing 3, J Buech 3, D Hoffmann 4, J Selbig 5, T Lengauer 3, D Häussinger 1

  1. University Clinic of Düsseldorf, Germany
  2. University of Cologne, Germany
  3. MPI for Informatics, Saarbrücken, Germany
  4. CAESAR Foundation, Bonn, Germany MPI for Molecular Plant Physiology, Golm, Germany

Background: Despite widespread application there is few evidence on the long-term outcome of salvage antiretroviral therapy (ART) of HIV infection guided by resistance testing. The aim of our study was to characterize the efficacy of this strategy.

Methods: A retrospective single-centre study at a university out-patient unit was carried out. Data were collected by chart review of all ART switches after virological failure with the help of resistance testing in 2000 and 2001, the follow-up period was 104 weeks. Genotyping test results were created by geno2pheno bioinformatics analysis and virologists expert interpretation.

Results: In the study period, 117 patients started salvage ART. 86,3% were male, median age was 40,7 years (24-73), 59,8% were homosexuals, 22,2% were at stage CDC C, median CD4 cell-count was 294/μl (1-931), median viral load was 7710/ml (166-500.001). Median duration of HIV-infection was 7,7 years (0,8-17,3), duration of previous ART was 252 weeks (22-843), number of previous ART drugs was 8 (2-15).

Median duration of new ART after switch was 65 weeks (3-104), duration until virological failure was 24 weeks (0-104). A second (third or more) resistance test was applied in 21,4% (14,5%), a second (third or more) ART switch within the follow-up period was carried out in 36,8% (19,7%).

In on-treatment- (intent-to-treat-) analysis, the proportion of patients with a viral load below 50 copies/ml was 46,7% (42,7%) at 24 weeks after initiation of salvage therapy, 46,1% (40,2%) after 48 weeks, 50,0% (41,0%) after 72 weeks, and 56,0% (43,6%) after 96 weeks, respectively. Median CD4 cell-count was 300/μl (14-1092) after 24 weeks, 300/μl (1-973) after 48 weeks, 326/μl (5-1030) after 72 weeks, and 347/μl (4-1221) after 96 weeks, respectively.

Conclusion: In this highly ART-experienced population, we showed good long-term efficacy of salvage therapy guided by genotyping and the geno2pheno interpretation system. More than half of the studied population required subsequent treatment modifications for this result, in about a third of the cases repeat resistance testing was necessary. In conclusion, genotypic resistance testing using geno2pheno leads to a sustained virological success in a large proportion of patients receiving salvage ART.