Predictors of successful genotype-guided antiretroviral therapy in treatment-experienced individuals over calendar years: a cohort study.

BACKGROUND: The continuous development of new drugs for use in triple-drug combination antiretroviral therapy (cART) has dramatically decreased morbidity and mortality in HIV-1 infected individuals. However, increasing drug resistance could be associated with a poor outcome. OBJECTIVES: To determine the efficacy of resistance genotype-guided antiretroviral regimens in combination antiretroviral therapy (cART)-failing patients over calendar years and its predictors. STUDY DESIGN: Patients, with an available resistance genotype performed between 1999 and 2008, who failed a highly active antiretroviral therapy (HAART) regimen, changed therapy within 6 months from genotype and maintained the same salvage regimen, were selected from a clinical cohort database. Virologic efficacy was analyzed using time-to virologic suppression (VS, HIV-1 RNA<50 copies/ml). RESULTS: In 270 sequences analyzed from 212 patients, after a median follow-up of 23 weeks, there were 160 patients with VS (59.3%). Mean regimens' genotypic sensitivity score (GSS) increased from 1.86 (SD+/-0.92) in 1999-2001, to 2.29 (SD+/-0.96) in 2005-2008 (p=0.001 for trend). VS was achieved in 39% of those patients genotyped in 1999-2001, and increased to 69% for patients with genotyping performed between 2005 and 2008 (p<0.001). More recent calendar year, younger age and less use of suboptimal therapy were predictors of more effective HAART regimens but only more recent calendar year maintained a trend toward significance in a multivariable model. More recent genotyping calendar year, younger age, lower number of HAART regimens experienced, lower HIV-1 RNA and higher GSS independently conveyed and increased the probability of VS. CONCLUSIONS: Resistance-guided salvage antiretroviral therapy was more effective during more recent calendar years, independent from other measurable confounders, including the GSS of the employed regimen. Convenience and tolerability of newer agents should account for the observed effect.

Atazanavir and lopinavir with ritonavir alone or in combination: analysis of pharmacokinetic interaction and predictors of drug exposure.

OBJECTIVES: Studies on the pharmacokinetic interaction between atazanavir and lopinavir with ritonavir (lopinavir/ritonavir) report contradictory results. We aimed to establish the in vivo interaction between these two protease inhibitors as well as the variables influencing drug exposure. METHODS: Pharmacokinetic parameters were investigated in HIV-infected patients treated with atazanavir 300 mg with ritonavir 100 mg q24h (group A) or lopinavir/ritonavir 400/100 mg q12h (group B) or atazanavir 300 mg q24h with lopinavir/ritonavir 400/100 mg q12h (group C). Patients receiving other concomitant protease inhibitors or non-nucleoside reverse transcriptase inhibitors were excluded. RESULTS: In group A (n=10), mean +/- standard deviation atazanavir C(min) was 390 +/- 460 ng/mL, C(max) 3051 +/- 1996 ng/mL and AUC(24) 29 913 +/- 17 686 ng/mL/h. In group B (n=9), lopinavir C(min) was 7562 +/- 4292 ng/mL, C(max) 12 944 +/- 4838 ng/mL and AUC(0-12) 122 313 +/- 38 225 ng/mL/h. In group C (n=7), atazanavir C(min) was 876 +/- 460 ng/mL (P=0.039 vs. group A), C(max) 3421 +/- 3399 ng/mL and AUC(0-24) 65 055 +/- 49 843 ng/mL/h (two-sided P>0.05 for each comparison with group A), lopinavir C(min) was 7471 +/- 3745 ng/mL, C(max) 10 143 +/- 5217 ng/mL and AUC(0-12) 104 501 +/- 43 565 ng/mL/h (P>0.05 for each comparison with group B). When analysing all the groups, including controls from routine clinical practice, higher body mass index was associated with lower atazanavir C(min) and with lower lopinavir C(max). Atazanavir C(min) showed a correlation with total bilirubin levels. CONCLUSIONS: Combination with lopinavir/ritonavir provides higher atazanavir C(min) than combination with ritonavir alone, possibly because of an effect of the additional ritonavir dose. Low BMI may be associated with higher drug exposure.

Genotypic resistance profile and clinical progression of treatment-experienced HIV type 1-infected patients with virological failure.

We explored the relationship between HIV-1 drug resistance in treatment-experienced patients and disease progression in a cohort of patients undergoing resistance testing to guide treatment decisions. A total of 601 treatment-failing individuals tested for genotypic HIV-1 drug resistance between 1998 and 2004 were selected. At genotypic testing, median HIV-1 RNA levels and CD4 counts were 3.8 log copies/ml and 293 cells/mul, respectively; 84% had resistance mutations to nucleoside reverse transcriptase inhibitors (NRTIs), 42% had resistance mutations to non-NRTIs, 51% had major resistance mutations to protease inhibitors (PI), 12% had no major resistance mutations to any drug class, 22% had mutations to one class, 42% had mutations to two classes, and 23% had mutations to three classes. During a follow-up of 714.7 patients/year, 80 patients showed an AIDS-defining event or died. In multivariable models adjusting for prior AIDS, baseline CD4 counts, HIV-1 RNA, and calendar year, viral resistance variables associated with increased hazards of clinical progression were the presence of reverse transcriptase substitution T215F (p = 0.002) and the presence of three or more protease substitutions among L33F/I/V, V82A/F/L/T, I84V, and L90M (p = 0.003). Resistance to three drug classes remained independently predictive of clinical progression only when calendar year was not used as an adjustment factor. Prevention and treatment of multiple drug class resistance are clinical priorities for HIV-infected patients. In recent years, improved treatment options may have helped in reducing part of the resistance-associated clinical progression.