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Predicting Kaletra Response in Treatment-Experienced Patients
 
 
  "Virological, intracellular and plasma pharmacological parameters predicting response to lopinavir/ritonavir (KALEPHAR Study)"
 
AIDS: Volume 18(9) 18 June 2004
 
Breilh, Dominiquea; Pellegrin, Isabelleb; Rouzés, Agnésa; Berthoin, Karinea; Xuereb, Fabiena; Budzinski, Hélèned; Munck, Michèlea; Fleury, Hervé JAb; Saux, Marie-Claudea; Pellegrin, Jean-Lucc
 
From the Departments of aPharmacokinetics and Clinical Pharmacy, bVirology and cInternal Medicine and Infectious Diseases, Victor-Segalen University, Bordeaux 2, France; and dUPRES A 5472 CNRS University, Bordeaux 1, France.Correspondence to Dr Dominique Breilh, Laboratoire de Pharmacocinétique et de Pharmacie Clinique, Pharmacie Centrale, Hôpital Haut-Lévêque, Avenue de Magellan, 33604 Pessac Cedex, France.
 
Received: 25 February 2003; revised: 23 October 2003; accepted: 27 January 2004.
 
Brief summary from Jules Levin: This study examined how to use Kaletra in achieving the most success for patients with previous protease inhibitor experience and resistance, i.e. to reduce viral load to undetectable (< 50 copies/ml) and increase CD4 count as much as possible. This is the goal of therapy for HIV. The authors of this study report that the number of baseline lopinavir (Kaletra) mutations and intracellular and plasma lopinavir Cmin were independently associated with virological success or failure. Cmin is the level of a drug at the end of the dosing period. So in the case of Kaletra, the Cmin is the level of lopinavir in the blood 12 hours after taking your last dose. The authors suggest that for PI resistant patients who are starting a Kaletra regimen, monitoring your blood (plasma) & intracellular levels of lopinavir can allow you to see if levels are low so you can consider increasing Kaletra dosing to maximize your potential for reducing viral load & increasing CD4 response. The authors also report that the number & types of PI drug resistance mutations you have can help in predicting how you will respond to Kaletra. This can help you in deciding what dose of Kaletra to use. Ongoing studies are examining higher doses of Kaletra for patients with PI resistance. At the 11th Retrovirus Conference in Feb 2004 there were reports on this and you can read NATAP reviews of higher dose Kaletra & additional relevant data:
 
"High Dose Kaletra in Highly Experienced Patients" where researchers report from this early study that higher doses of LPV/r may provide LPV concentrations sufficient to overcome certain degrees of reduced LPV phenotypic susceptibility, resulting in a significant treatment effect.
http://www.natap.org/2004/CROI/croi_27.htm
 
"Pharmacokinetics findings of studying high dose Kaletra (lopinavir/ritonavir)" and "Genotypic Inhibitory Quotient, Lopinavir Blood Levels & Number of Resistance Mutations Predict Viral Response; Increases in Lipids & Drug Blood Levels" (written by Ronald Reisler, MD)
http://www.natap.org/2004/CROI/croi_40.htm
 
SUMMARY. The authors say: Our pharmacokinetic results confirmed that plasma lopinavir levels should be adapted to obtain a virological response to lopinavir/ritonavir-based HAART. Compared with previously estimated plasma lopinavir Cmin efficacy thresholds of approximately 4 mg/ml and more than 5.7 mg/ml, respectively, our most discriminatory estimate was 4 mg/ml (when considering fewer than five baseline lopinavir resistance mutations). Few data concerning the relevance of in-vivo intracellular PI concentrations as a factor predictive of virological success or failure on HAART are available, and defining an intracellular lopinavir threshold for clinical use is difficult.
 
For our patients with plasma lopinavir Cmin greater than 4 mg/ml, their intracellular lopinavir Cmin did not add relevant information. However, our data highlighted the ability of an intracellular lopinavir Cmin greater than 8 mg/ml to predict virological success in patients with an insufficient plasma concentration between 2.5 and 4 mg/ml. Finally, for patients with plasma lopinavir Cmin less than 2.5 mg/ml, the intracellular lopinavir concentration merely indicated that rapidly raising the lopinavir/ritonavir dose is imperative.
 
Although we obtained good correlations between intracellular and plasma lopinavir concentrations, suggesting passive uptake of the drug, no correlation was found between (intracellular/plasma) lopinavir Cmin ratios at month 1 versus month 6. The latter suggests enhanced expression of multidrug resistance transporters as a potential mechanism for decreased drug intracellular availability.
 
In agreement with other studies, we found that months 1 and 6 GIQ were strongly associated with virological success. Furthermore, we confirmed that GIQ rather than individual virological and pharmacokinetic parameters should be used in therapeutic drug monitoring to calculate a target concentration.
 
"...Multivariate analysis showed that the number of baseline lopinavir mutations and intracellular and plasma lopinavir Cmin were independently associated with virological success or failure... In this study, the HIV protease mutations associated with poorer in-vivo virological responses to lopinavir/ritonavir at month 6 were L10F/I/V (P < 0.02), I54L/T/V (P < 0.05), 71I/L/T/V (P < 0.05) and V82A/F/T/S (P < 0.01). The number of protease gene mutations was inversely associated with the virological response (P < 0.01). The isolates from good responders had five or fewer mutations: among patients with one to three or four to five lopinavir mutations, 77 or 82%, respectively, achieved virological success, whereas only one of the 10 patients with six to eight lopinavir mutations mounted a persistent virological response at month 6... Univariate analysis indicated that higher intracellular and plasma lopinavir Cmin at months 1 and 6 were significantly associated with virological success, and intracellular and plasma GIQ at these times were strongly associated with virological success or failure. The multivariate analysis retained lopinavir mutations at baseline (b = 0.46, P = 10-4), month 1 plasma lopinavir Cmin (b = -0.52, P < 2.10-4) and month 6 intracellular lopinavir Cmin (b = -0.54, P < 0.01) as independent factors associated with virological failure on lopinavir/ritonavir. Using the most discriminatory c2 value at month 1, the most discriminatory efficacy threshold estimates 8 mg/ml and 4 mg/ml for intracellular and plasma lopinavir Cmin, respectively. The plasma lopinavir Cmin was < 4 mg/ml in 29 patients (76.3%); 11 (38%) of whom achieved virological success (8/11 with lopinavir intracellular Cmin >= 8 mg/ml), whereas the 17 others (44.7%) deemed virological failures had intracellular lopinavir Cmin < 8 mg/ml. All nine patients (23.7%) with plasma lopinavir Cmin of 4 mg/ml or greater achieved virological success; all their intracellular lopinavir Cmin was 8 mg/ml or greater. Nineteen patients (50%) had plasma lopinavir Cmin values between 2.5 and 4 mg/ml. All patients with plasma Cmin values less than 2.5 mg/ml failed on lopinavir/ritonavir, regardless of the number of lopinavir mutations. The month 1 intracellular lopinavir GIQ was 3 or greater in 17 out of 38 patients, 15 of whom achieved virological success at month 6. The month 1 plasma lopinavir GIQ was 1 or greater in 17 out of 38 patients; 14 of whom achieved virological success at month 6.
 
Abstract
 
Objectives: To assess the impact of HIV-1 protease mutations and intracellular and plasma lopinavir minimum concentrations (Cmin) on virological success or failure on lopinavir/ritonavir-containing highly active antiretroviral therapy (HAART).
 
Design: HIV-1-infected HAART-experienced patients included in an observational study, received lopinavir/ritonavir (400/100 mg twice a day) plus two to three nucleoside reverse transcriptase inhibitors (NRTI) or one NRTI plus one non-NRTI. A viral load less than 50 copies/ml at month 6 defined virological success.
 
Methods: Intracellular and plasma lopinavir concentrations were determined by high-pressure liquid chromatography with mass-spectrometry detection. Reverse transcriptase and protease genes were sequenced at baseline and the time of virological failure.
 
Results: When the 38 patients started the lopinavir/ritonavir-based regimen, baseline median (25-75th percentile) values were: CD4 cell count 218 cells/ml (133-477); plasma HIV-1-RNA load 5.3 log10 copies/ml (3.8-5.1); number of lopinavir mutations four per protease gene (two to six).
 
Univariate analysis associated virological success or failure at month 6 (21/38 patients) with the number of baseline lopinavir mutations, intracellular and plasma lopinavir Cmin, and the genotype inhibitory quotient (GIQ) at months 1 and 6.
 
Multivariate analysis showed that the number of baseline lopinavir mutations and intracellular and plasma lopinavir Cmin were independently associated with virological success or failure. We defined the most discriminating intracellular and plasma lopinavir Cmin efficacy thresholds (8 and 4 mg/ml, respectively) and GIQ thresholds (1 and 3, respectively).
 
Conclusion: The monitoring of lopinavir/rironavir-based HAART efficacy should include the number of baseline lopinavir/ritonavir mutations, intracellular and plasma lopinavir Cmin and GIQ calculation.
 
Introduction
 
Pharmacokinetic parameters and virological characteristics have individually been associated with virological success in response to highly active antiretroviral therapy (HAART). Currently available protease inhibitors (PI) exhibit threshold pharmacokinetics with minimum concentrations (Cmin) falling near or below the levels required to inhibit fully the replication of wild-type HIV-1 in vitro. PI accumulate intracellularly to different degrees, and their antiviral activities are strongly associated with their intracellular concentrations.
 
Lopinavir, a PI co-formulated with ritonavir, achieved a mean lopinavir Cmin : 50% inhibitory concentration ratio for wild-type HIV greater than 75, suggesting it could potentially provide a genetic barrier to the emergence of viral resistance, while maintaining activity against resistant virus. Lopinavir/ritonavir has significant potency in antiretroviral-naive patients, or those with single or multiple PI failures. PI resistance usually results from multiple protease gene mutations among the 13 known mutations, reflecting previous PI exposure. Clinical trials showed the number of baseline mutations to be predictive of virological success or failure on a regimen including lopinavir/ritonavir.
 
Recent studies combined virological genotype predicted resistance levels and pharmacokinetic (PI Cmin) parameters to obtain the genotype inhibitory quotient (GIQ) and assessed its ability to predict virological success or failure. The ideal Cmin : resistance index ratio for optimal antiviral efficacy with tolerable plasma drug concentrations remains unknown.
 
We evaluated the impact of intracellular and plasma lopinavir pharmacokinetic parameters, HIV-1 protease gene mutations and intracellular and plasma GIQ on the virological success or failure of patients on lopinavir/ritonavir-containing HAART.
 
Study population
 
HIV-1-infected, antiretroviral-experienced, lopinavir/ritonavir-naive patients were enrolled in this observational study. Initially, all patients received tritherapy including two to three nucleoside reverse transcriptase inhibitors (NRTI) plus lopinavir/ritonavir (400/100 mg, twice a day) or one NRTI plus efavirenz plus lopinavir/ritonavir (533/133 mg, twice a day). Plasma lopinavir concentration monitoring was scheduled for all patients at month 0, and 1, 3 and 6 months after the first lopinavir/ritonavir administration; these results served as controls of treatment compliance. Blood samples were drawn for plasma HIV-1-RNA determinations (copies/ml were quantitated using the VERSANTTM HIV-1 RNA 3.0 assay; Bayer Diagnostics, Puteaux, France) and CD4 cell counts at each follow-up visit, and for intracellular and plasma lopinavir pharmacokinetics at months 1 and 6. Plasma HIV-1-RNA levels falling to less than 50 copies/ml during the first months of the lopinavir/ritonavir regimen and remaining consistently low at month 6 defined virological success.
 
Results
Baseline characteristics of patients

 
Thirty-eight patients [32 men and six women; mean age 43 years (range 31-59)] were enrolled in this observational cohort study and started on a lopinavir/ritonavir-based regimen. The antiretroviral drugs prescribed in combination with lopinavir/ritonavir at baseline were as follows: abacavir plus one NRTI, n = 7 (18.4%); abacavir plus two NRTI, n = 12 (31.6%); efavirenz plus one NRTI, n = 5 (13.2%); two NRTI selected from zidovudine, lamivudine, didanosine and stavudine, n = 14 (36.8%). Baseline isolates from 15 out of 38 (39.5%), 13 out of 38 (34.2%) and 10 out of 38 (26.3%) patients carried, respectively one to three, four or five and six to eight lopinavir resistance mutations. The mean number of NRTI resistance mutations was four (one to nine) and 21 patients had RT sequences harbouring a mean of two (one to four) non-NRTI-resistance mutations.
 
Baseline CD4 count & viral load for patient successes & failures (<50 copies/ml defined as success): success (n=21)- 4.1 log10 copies/ml; cd4 count 405; 2lopinavir mutations. Failure- 4.8 log10 copies/ml; 179 cd4 count; 5 lopinavir mutations. The differences in CD4 & viral load at baseline were not statistically significant, but the difference in lopinavir mutations was significant (p<0.01).
 
Analysis of pharmacokinetic parameters
 
Intracellular and plasma lopinavir Cmin at months 1 and 6 (r 2 = 0.72, P = < 10-6) (r 2 = 0.17, P = 0.3), months 1-6 intracellular lopinavir Cmin (r 2 = 0.67, P = 5.10-6) and months 1-6 plasma lopinavir Cmin (r 2 = 0.53, P = 7.10-4) were correlated; no correlation was found between lopinavir Cmin intracellular : plasma ratios at months 1 and 6.
 
Virological outcome according to pharmacokinetic and baseline virological parameters
 
A mean increase of +82 (-276; +526) CD4 cells/ml was observed between months 0 and 6. Median plasma HIV-1-RNA loads decreased to 1.5 (-4.6; +1.8) log10 copies/ml at month 6, when the 21 patients (55.3%) having undetectable (< 50 copies/ml) loads were considered virological successes.In this study, the HIV protease mutations associated with poorer in-vivo virological responses to lopinavir/ritonavir at month 6 were L10F/I/V (P < 0.02), I54L/T/V (P < 0.05), 71I/L/T/V (P < 0.05) and V82A/F/T/S (P < 0.01). The number of protease gene mutations was inversely associated with the virological response (P < 0.01). The isolates from good responders had five or fewer mutations: among patients with one to three or four to five lopinavir mutations, 77 or 82%, respectively, achieved virological success, whereas only one of the 10 patients with six to eight lopinavir mutations mounted a persistent virological response at month 6.Univariate analysis indicated that higher intracellular and plasma lopinavir Cmin at months 1 and 6 were significantly associated with virological success, and intracellular and plasma GIQ at these times were strongly associated with virological success or failure. The multivariate analysis retained lopinavir mutations at baseline (b = 0.46, P = 10-4), month 1 plasma lopinavir Cmin (b = -0.52, P < 2.10-4) and month 6 intracellular lopinavir Cmin (b = -0.54, P < 0.01) as independent factors associated with virological failure on lopinavir/ritonavir. Using the most discriminatory c2 value at month 1, the most discriminatory efficacy threshold estimates 8 mg/ml and 4 mg/ml for intracellular and plasma lopinavir Cmin, respectively. The plasma lopinavir Cmin was < 4 mg/ml in 29 patients (76.3%); 11 (38%) of whom achieved virological success (8/11 with lopinavir intracellular Cmin >= 8 mg/ml), whereas the 17 others (44.7%) deemed virological failures had intracellular lopinavir Cmin < 8 mg/ml. All nine patients (23.7%) with plasma lopinavir Cmin of 4 mg/ml or greater achieved virological success; all their intracellular lopinavir Cmin was 8 mg/ml or greater. Nineteen patients (50%) had plasma lopinavir Cmin values between 2.5 and 4 mg/ml. All patients with plasma Cmin values less than 2.5 mg/ml failed on lopinavir/ritonavir, regardless of the number of lopinavir mutations. The month 1 intracellular lopinavir GIQ was 3 or greater in 17 out of 38 patients, 15 of whom achieved virological success at month 6. The month 1 plasma lopinavir GIQ was 1 or greater in 17 out of 38 patients; 14 of whom achieved virological success at month 6.
 
Evolution of the protease genotype in patients failing on lopinavir/ritonavir
 
Protease gene sequencing was performed at the time of virological failure for these 17 patients: six patients had no new PI resistance mutations although four of them had four or fewer lopinavir mutations at baseline; whereas different PI resistance mutations emerged in the 11 others on lopinavir/ritonavir. In four patients, protease genes harboured one new mutation at position K20R, L24I, F53L or G73T; two new mutations emerged in three patients at positions M36I+L63P, A71T+L90M and V32I+A71L; and the following patterns of new mutations emerged in one patient each: I47V+I54V+G73T, L10I+M46I+V82A+I84V, V32I+ L33F+I47V+I54V+L63P, and L10F+V32I+L33F+M46I +I47V+V77I+V82A. Notably, patients with few secondary mutations and those with five or more mutations, including primary mutations, in their baseline HIV protease genes developed new mutations on lopinavir/ritonavir. The L54V mutation, associated with lower susceptibility to lopinavir, was detected in two patients but the I50V mutation, which mediates the emergence of virus resistance to lopinavir and amprenavir was not selected in any of our patients.
 
 
 
 
 
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