Virologic therapy response significantly correlates with the number of active drugs as evaluated using a LiPA HIV-1 resistance scoring system.
BACKGROUND
Resistance testing is increasingly accepted as a tool in guiding the selection of human immunodeficiency virus type 1 (HIV-1) antiretroviral therapy in HIV-1 infected individuals who fail their current regimen.


OBJECTIVE
To descriptively compare the correlation between virologic treatment response and results using three genotypic HIV-1 drug resistance interpretation systems: the VERSANT HIV-1 Resistance Assay (LiPA) system and two sequence-based interpretation systems.


METHODS
Specimens from 213 HIV-1-infected subjects, either starting (n=104) or switching to (n=109) a regimen of three or four antiretroviral drugs, were collected retrospectively at baseline and after 3 months of uninterrupted therapy. The correlation between viral load change and the number of predicted active drugs in the treatment regimen was assessed. An interpretation algorithm was recently developed to process VERSANT HIV-1 Resistance Assay (LiPA) data. The number of active drugs predicted using this algorithm was rank correlated with the viral load change over a 3-month treatment period. For comparison, a similar calculation was made using two sequence-based algorithms (REGA version 5.5 and VGI GuideLines Rules 4.0), both applied on the same sequences.


RESULTS
Statistically significant (p<0.05) correlation coefficients for each of the three HIV-1 drug resistance interpretation systems were observed in the treatment-experienced subjects on a 3-drug regimen (-0.39, -0.38, and -0.42, respectively) as well as on a 4-drug regimen (-0.33, -0.31, and -0.37, respectively). However, no significant correlation was observed in treatment-naive subjects, probably due to the very low frequency of drug resistance in these subjects.


CONCLUSIONS
All three genotypic drug resistance interpretation systems (LiPA version 1, REGA version 5.5, and VGI GuideLines Rules 4.0) were statistically significantly correlated with virologic therapy response as measured by viral load testing.
Ziermann
Rainer
R
Bayer HealthCare LLC, Diagnostics Division, 800 Dwight Way, Berkeley, CA 94710, USA.
Celis
Linda
L
Derdelinckx
Inge
I
Lambert
Christine
C
Veeck
Jürgen
J
Rizzo
Maria Gabriella
MG
Vanderborght
Bart
B
Zissis
Georges
G
Clumeck
Nathan
N
Fransen
Katrien
K
Vaira
Dolores
D
Hendricks
David
D
Van Laethem
Kristel
K
Vandamme
Anne-Mieke
AM
Schmit
Jean-Claude
JC
Knechten
Heribert
H
De Luca
Andrea
A
Louwagie
Joost
J
Segers
Pascale
P
De Boeck
Kristel
K
Pottel
Hans
H
De Brauwer
Annelies
A
Hulstaert
Frank
F
D000328:Adult; D000465:Algorithms; D019380:Anti-HIV Agents / Q000494:pharmacology* / Q000627:therapeutic use; D024882:Drug Resistance, Viral / Q000235:genetics; D005260:Female; D015658:HIV Infections / Q000188:drug therapy* / Q000821:virology; D015497:HIV-1 / Q000187:drug effects* / Q000235:genetics; D006801:Humans; D016015:Logistic Models; D008297:Male; D008875:Middle Aged; D015337:Multicenter Studies as Topic; D011933:Reagent Kits, Diagnostic; D012189:Retrospective Studies; D016896:Treatment Outcome
D019380:Anti-HIV Agents; D011933:Reagent Kits, Diagnostic