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Raltegravir+Etravirine - Virological and immunological response in HIV-1-infected patients with multiple treatment failures receiving raltegravir and optimized background therapy, ANRS CO3 Aquitaine Cohort
 
 
  Journal of Antimicrobial Chemotherapy March 2009 63(6):1251-1255
 
"Patients with etravirine in the OBT had slightly lower PK parameters, but there was no statistically significant effect of etravirine on raltegravir PK parameters."
 
Linda Wittkop1,2,*,{dagger}, Dominique Breilh3,4,{dagger}, Daniel Da Silva5, Pierre Duffau6, Patrick Mercie6, Isabelle Raymond6, Guerric Anies5, Herve Fleury5, Marie-Claude Saux3,4, Francois Dabis1,2, Catherine Fagard1,2, Rodolphe Thiebaut1,2, Bernard Masquelier5 and Isabelle Pellegrin5,{ddagger}
 
1 Inserm, Unit 897 Epidemiology and Biostatistics, Bordeaux, France 2 University Victor Segalen Bordeaux 2, ISPED, Bordeaux School of Public Health, Bordeaux, France 3 Department of Clinical Pharmacokinetics and Clinical Pharmacy and EA 2968, University Victor Segalen, Bordeaux, France 4 Pharmacy Haut-Levźque Hospital, Bordeaux University Hospital, Pessac, France 5 Department of Virology and EA 2968, Bordeaux University Hospital, University Victor Segalen, Bordeaux, France 6 Department of Internal Medicine and Infectious Diseases, Bordeaux University Hospital, University Victor Segalen, Bordeaux, France
 
Abstract
 
Background: The efficacy of raltegravir plus optimized background therapy (OBT) has been demonstrated for antiretroviral (ARV)-experienced HIV-1-infected patients in randomized clinical trials. We studied viro-immunological response, pharmacokinetic parameters and genotypic test results in an observational cohort of multiple ARV class-experienced patients starting a raltegravir-based regimen.
 
Methods: Already enrolled ANRS CO3 Aquitaine Cohort patients with virological failure were included in this study after starting a raltegravir-based regimen (400 mg twice a day, week 0). Virological success was defined by the plasma HIV-1 RNA level [viral load (VL)] <2.7 log10 copies/mL at week 12 and <1.7 log10 copies/mL at week 24. One patient was excluded from further analysis (no follow-up after week 4).
 
Results: Fifty-one patients [male/female = 43/8, median age = 48 (interquartile range = 43, 55) years] were included. At week 0, median CD4 count was 244 (110; 310)/mm3 and median VL was 4.2 (3.6, 4.7) log10 copies/mL. At week 24, 39 (78%) patients experienced virological success: 4 (44%), 14 (82%) and 21 (87%) patients with a genotypic sensitivity score <1, ≥1 and <2 and ≥2 (P = 0.02), respectively. Raltegravir-related mutations emerged in 9 of 11 failing patients (82%): Q148H/R (n = 5), N155S/H (n = 3) and S230N (n = 1). Median CD4 increases from week 0 to week 4 and week 24 were 28 (–4, 85) and 57 (0, 156) cells/mm3, respectively. A poor immune response was independently associated with a lower VL decline (week 0 to week 12) [odds ratio (OR): 3.5, 95% confidence interval (CI): 1.4, 8.4, for 1 log10 less] and CD4+% at baseline (OR: 2.6, 95% CI: 0.97, 8.3, for 10% lower).
 
Conclusions: Raltegravir plus OBT provided a good virological success rate in highly pre-treated patients under clinical routine conditions.
 
Introduction
 
Raltegravir is a HIV-1 integrase inhibitor that has been successfully used in both treatment-naive patients1 and heavily treated patients.2,3
 
We studied the viro-immunological response of raltegravir with optimized background therapy (OBT) in an observational prospective cohort of multiple antiretroviral (ARV) class-experienced patients under clinical routine conditions. Furthermore, we evaluated the pharmacokinetic (PK) parameters and genotypic test results of integrase, reverse transcriptase and protease genes at baseline and in failing patients.
 
Results
 
Baseline patient characteristics

 
The baseline characteristics of the 51 patients enrolled in this observational cohort study are reported in Table 1. Most of the patients (72%) received raltegravir as part of an expanded access programme in France (Autorisation Temporaire d’Utilisation). ARV drugs frequently prescribed as OBT were ritonavir-boosted darunavir (n = 36, 71%), etravirine (n = 22, 43%) and enfurvitide (n = 13, 25%). Raltegravir in combination with ritonavir-boosted darunavir and etravirine was prescribed in 15 patients (29%). The most frequent NRTIs co-prescribed with raltegravir were tenofovir (n = 20, 39%), emtricitabine (n = 18, 35%) or lamivudine (n = 11, 22%).
 
Responses to the raltegravir-containing therapy
 
Virological response. Virological success was observed for 39 patients (78%) (Table 2). According to a GSS of <1, ≥1 to <2 and ≥2, virological success occurred in 4 (44%), 14 (82%) and 21 (88%) patients (P = 0.02) with a VL decline (from baseline to week 24) of –0.64 (–2.8, –0.3), –2.4 (–3.1, –1.1) and –2.2 (–2.9, –1.6) log10 copies/mL (P = 0.27), respectively. Among the 26 integrase PMs having a prevalence >10% from the baseline genotype, the PM T206S (n = 8, 18%) was significantly associated with a lower response rate (P = 0.02). Furthermore, the clinical AIDS stage [odds ratio (OR): 0.2, 95% confidence interval (CI): 0.05, 0.80, for C versus A/B, P = 0.02], the nadir of CD4+ cell count (OR: 1.6, 95% CI: 1.1, 2.1, for a difference of 10 cells/mm3, P = 0.006), the absolute value of CD4+ cell count at baseline (OR: 5.9, 95% CI: 1.9, 18.1, for a difference of 100 cells/mm3, P = 0.002) and the HIV-1 RNA level at baseline (OR: 0.1, 95% CI: 0.04, 0.5, for a difference of 1 log10 copies/mL, P = 0.002) were significantly associated with virological response in univariable analysis. In the adjusted analysis, initial VL (OR: 0.2, 95% CI: 0.06, 0.98, for 1 log10 copies/mL higher, P = 0.046) and the nadir of CD4+ cell count (OR: 1.6, 95% CI: 1.0, 2.7, for 10 cells/mm3 higher, P = 0.049) were independently associated with virological response.
 
Immune response. A CD4+ gain (baseline to week 24) ≤50 cells/mm3 was found in 20 patients. In adjusted logistic regression, a poor immune response was independently associated with a lower VL decline (weeks 0–12) (OR: 3.5, 95% CI: 1.4, 8.4, for 1 log10 less, P = 0.009) and CD4+% at baseline (OR: 2.6, 95% CI: 0.97, 8.3, for 10% lower, P = 0.08), but did not explain the whole variability of CD4+ response (R2 = 0.29). At week 24, 32 patients had a VL <1.7 log10 copies/mL (one patient with missing values for CD4+ cells) and for 12 of them, we observed a CD4+ gain of ≤50 cells/mm3 (38%, 95% CI: 22, 56). These patients had similar baseline CD4+ cell counts (249 versus 246/mm3), almost similar nadir of CD4+ cell count (146 versus 117/mm3) and lower VL at week 0 (3.4 versus 4.3 log10 copies/mL) than patients with both virological and immunological success (n = 20).
 
PK parameters
 
Raltegravir PK parameters were stable during follow-up. Median Cmin was 250 (150, 350), 300 (200, 350) and 290 (150, 350) ng/mL at weeks 4, 12 and 24, respectively. Median Cmax was 1000 (870, 1400) ng/mL at week 4, 990 (800, 1200) ng/mL at week 12 and 980 (780, 1200) ng/mL at week 24. The minimal observed value of Cmin was 50 ng/mL (0.10 ĶM) for each follow-up visit, exceeding the 95% inhibitory concentration (IC95) of 0.033 ĶM. Patients with etravirine in the OBT had slightly lower PK parameters, but there was no statistically significant effect of etravirine on raltegravir PK parameters.
 
Emerging integrase mutations
 
Four different patterns of emerging mutations were observed: (i) five patients presented the emergence of Q148H/R with secondary mutations (V72I, L74M, G140A/S, E138A, K156N, K160N, V201I and T206S); (ii) the N155S/H mutation emerged in three patients and was replaced in the following 3–5 months by a pattern including the mutation Y143C/H/R and secondary mutations (L74M, T97A, G163R, V151I and S230R); (iii) the S230R mutation was selected in one patient; and (iv) two patients had virological failure without emerging mutations.
 
Discussion
 
We observed a potent ARV effect in patients who had been failing multiple previous ARV regimens. Our findings were comparable to virological success rates observed in similar populations with heavily treatment-experienced patients2,3 on raltegravir-based HAART. Despite a rapid VL suppression, the overall median CD4+ cell rise was 57 (0, 156)/mm3 between baseline and week 24, comparable to that observed in the protocol 005 and BENCHMRK studies.2,3 A poor immune response was associated with VL decline and CD4+% at baseline, but explained only ~30% of the entire variability of the CD4+ response. We found a discordant response (VL <1.7 log10 copies/mL and CD4+ gain ≤50 cells/mm3) in 38% of patients at week 24. Further investigation is needed to evaluate other hypotheses such as permanent immune activation, host factors or thymus exhaustion for a poor immune response despite virological success.
 
Factors associated with virological response at week 24 were the VL at baseline and the nadir of CD4+ cell counts. These findings are in agreement with the fact that most of the patients were already in an advanced disease stage.
 
The high proportion of integrase resistance mutations that developed in patients who failed therapy (9/11, 82%) in this study was consistent with findings in BENCHMRK studies (68%)3,6 and the protocol 005 study (92%).7 Our findings confirm the low genetic barrier of raltegravir. The low genetic barrier may have an influence on future drug options, especially in comparable patients, as cross-resistance to elvitegravir and other integrase inhibitors under investigation has already been reported.8
 
PK parameters did not provide a statistically meaningful predictive value for virological success, probably due to the fact that observed Cmin values were quite homogeneous and exceeded the IC95 of raltegravir in all patients. Etravirine co-prescription did not influence raltegravir PK parameters, confirming the negligible PK interaction between etravirine and raltegravir observed in healthy subjects.10
 
Conclusions
 
Raltegravir plus OBT provided a good virological success rate in HIV-1-infected heavily pre-treated patients with multiple treatment failures under clinical routine conditions comparable to that reported in randomized clinical trials.
 
Patients and methods
 
Study population

 
The patients were selected from the ANRS CO3 Aquitaine Cohort, a prospective hospital-based cohort of HIV-1-infected patients in south-western France. Informed consent was obtained for all patients. The Aquitaine Cohort has Institutional Review Board (IRB) approval from the Bordeaux University IRB.
 
Patients who experienced multiple virological failure on highly active antiretroviral therapy (HAART) {plasma HIV-1 RNA level [viral load (VL)] >1.7 log10 copies/mL} were consecutively enrolled in the present study between October 2006 and February 2008 after the onset of raltegravir (400 mg twice a day)-based HAART (week 0). The patients were monitored at weeks 0, 4, 12 and 24. Clinical, biological and therapeutic data were collected prospectively at each visit.
 
Virological and immunological outcomes
 
Virological success was defined as plasma VL <2.7 log10 copies/mL at week 12 and <1.7 log10 copies/mL at week 24, quantified using the CobasTaqman HIV assay (Roche Diagnostics, Basel, Switzerland). Patients with missing VL values at week 24 were considered as virological success if the VL was <2.7 log10 copies/mL at week 12. One patient had no follow-up visit after week 4 and was excluded from further analysis. A poor immune response was defined as a gain of CD4+ cells ≤50 cells/mm3 from week 0 to week 24.
 
Genotype resistance testing
 
Sequencing procedures used for reverse transcriptase, protease and integrase are available on the HIV French resistance web site.4 Complete integrase gene sequence was determined at baseline and in patients with virological failure.
 
We calculated the genotypic sensitivity score (GSS) that represents the sum of genotypic sensitivities (according to the ANRS genotype interpretation algorithm) to the drugs in the OBT.
 
Determination of plasma raltegravir concentrations
 
Blood samples were drawn to determine plasma raltegravir concentrations at the PK steady state 4 weeks after starting raltegravir, as well as at weeks 12 and 24. Minimum (Cmin) and maximum (Cmax) serum drug concentrations, corresponding to ~12 and 3 h after raltegravir ingestion, respectively, were measured using validated HPLC with mass spectrometry detection.5
 
Statistical analyses
 
Analyses were performed using SAS 9.1 (SAS Institute, Inc., Cary, NC, USA). Patients' characteristics were compared between groups using a Fisher's exact test for qualitative variables, and a Wilcoxon–Mann–Whitney test or a Kruskal–Wallis test for quantitative variables. Distributions are described as medians (25th, 75th percentiles), unless stated otherwise. We tested the following variables for their association with virological failure: patients' characteristics, prior treatments, baseline viro-immunological parameters, number of protease inhibitors, nucleoside reverse transcriptase inhibitor (NRTI) and non-NRTI resistance-related mutations, GSS, PK parameters and integrase polymorphisms (PMs) having a prevalence >10%. Factors associated with virological success and with a poor immune response were analysed using logistic regression.
 
 
 
 
 
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