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Abstract
CCTG 575: A RANDOMIZED, PROSPECTIVE STUDY OF PHENOTYPE TESTING (PHENO) VERSUS STANDARD OF CARE (SOC) FOR PATIENTS FAILING ANTIRETROVIRAL THERAPY (ARV)
HAUBRICH R, KEISER P, KEMPER C, WITT M, LEEDOM J, FORTHOL D, HELLMANN N
Objective: To compare PHENO (ViroLogic assay) to SOC to improve virologic response to ARV.
Methods: Randomized, prospective study in 256 patients with >6 months ARV, 1 prior PI (amended to 2), and entry HIV RNA >400. PHENO patients had phenotype determined whenever HIV RNA was >400. HIV RNA outcomes (month 6 and 12) were the area based change and percent <400.
Results: Characteristics of 238 patients completing baseline were not different between groups. Overall, the median CD4 was 277, median HIV RNA was 4.0, median months of prior ARV was 36 (18 months PI), and 76% were NNRTI naïve. Significant differences in selection of NRTI for the baseline regimen were noted (d4T and ddI increased, ABC decreased in PHENO vs SOC) due to imprecise cut-points for the drugs. The reduction in HIV RNA at month 6 (0.71 vs 0.69; PHENO vs SOC) and the proportion <400 (both groups = 48%) were not different nor were there differences at month 12. In a subgroup with >3 resistant PI (fold change >2.5), 50% of PHENO vs 17% SOC were <400 at month 6 (P=0.02). PHENO patients with >60 months ARV also had greater % < 400 at month 6 than SOC (69% vs 40%, P=0.05). The number of susceptible (phenotype fold change <2.5) NNRTI and PI, but not NRTI, in the baseline regimen were strong independent predictors of the % <400 at months 6 and 12 (controlling for CD4 and HIV RNA; p<0.006). Use of alternative NRTI sensitivity cut-points improved the predictive value of NRTI phenotype.
Conclusions: The similar HIV suppression in both arms may reflect the need for more precise sensitivity cut-off values for d4T and ddI in the PHENO arm and the improved ability to salvage these single PI (NNRTI naïve) treatment failures, leading to a good response (48% undetectable) in the SOC arm. However, baseline phenotype remained a strong independent predictor of outcome. This study will help to improve the utility of phenotypic assays by clarifying the clinically relevant sensitivity cut-points.
The 1st. IAS Conference on HIV Pathogenesis and Treatment
Abstract no.
127
Suggested Citation
"HAUBRICHR, et al.
CCTG 575: A RANDOMIZED, PROSPECTIVE STUDY OF PHENOTYPE TESTING (PHENO) VERSUS STANDARD OF CARE (SOC) FOR PATIENTS FAILING ANTIRETROVIRAL THERAPY (ARV).
Oral Presentation:
The 1st. IAS Conference on HIV Pathogenesis and Treatment
:
Abstract no.
127"
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