A Clinical Study of the Combination of 100 mg Ritonavir plus 800 mg Indinavir as Salvage Therapy: Influence of Increased Plasma Drug Levels in the Rate of Response

Abstract

Purpose: The purpose of our study was to evaluate the efficacy of indinavir (IDV) in a twice daily dosing regimen with coadministration of 100 mg ritonavir (RTV) and to explore the influence of plasma drug levels in the rate of virologic response. Method: We performed a prospective study of 59 patients who switched to a salvage regimen with two nucleoside analogs plus the combination of 100 mg RTV plus 800 mg IDV twice daily. Pharmacokinetics of IDV and RTV were assessed in 11 patients. Results: Previous antiretroviral exposure was 44 months, and 78% and 39% of patients had previously failed regimens with either IDV or RTV. Median CD4 count was 248 × 10⁶/L and HIV load was 3.9 log₁₀ copies/mL. The median number of mutations in the protease gene was 9 (3–14), predominantly at residues 82 (53%), 90 (42%), and 46 (32%). After 24 weeks, 61% of patients had a viral load decrease greater than 1 log₁₀, and 38% had a viral load below 50 copies/mL. Nephrolitiasis, hematuria, or flank pain was observed in 13 patients (22%), leading to withdrawal in six cases (10%). IDV trough levels were well above the IC₉₅ (median 1.75 mg/L, interquartile range 1.07-2.57), but RTV trough levels were below the IC₉₅ in 88% of patients. There was a close correlation between higher peak levels of IDV, virological response, and renal toxicity. Conclusion: RTV/IDV 100/800 mg in a twice daily dosing regimen is associated with a significant virological response in patients with antiretroviral treatment failure. The correlation between plasma drug levels, toxicity, and response suggests the usefulness of individualized drug monitoring.     

Pharmacokinetics and safety of tenofovir disoproxil fumarate on coadministration with lopinavir/ritonavir

OBJECTIVE: Lopinavir/ritonavir (LPV/r) and tenofovir disoproxil fumarate (TDF) are frequently used antiretrovirals. A pharmacokinetic study in healthy volunteers was conducted to assess the potential for a drug interaction between these agents. METHODS: This was a 36-day, multiple-dose, drug-drug interaction study of TDF and lopinavir/ritonavir (LPV/r). Subjects received TDF alone for 7 days, followed by 14 days each of TDF plus LPV/r and LPV/r alone in a randomized manner. Pharmacokinetic assessments were performed over 24 hours on days 7, 21, and 35. LPV/r and tenofovir plasma/serum concentrations were measured by high-performance liquid chromatography/mass spectometry (MS)/MS. Geometric mean ratios and 90% confidence intervals of pharmacokinetic parameters for tenofovir, LPV, and ritonavir (RTV) were estimated using analysis of variance and compared with the no-effect criterion for pharmacokinetic equivalence. RESULTS: Tenofovir measurements with an area under the concentration-time curve over the dosing interval, maximum concentration, and concentration at the end of the dosing interval (Ctau) were 32%, 15%, and 51% higher, respectively, when TDF was coadministered with LPV/r (n = 24). LPV and RTV pharmacokinetics, including Ctau, were unaffected by TDF (n = 24). Clinical estimates of renal function were unaffected by administration of TDF alone or with LPV/r. DISCUSSION: Coadministration of TDF with LPV/r resulted in increased tenofovir exposures at steady state, possibly through increased absorption. This increase is not believed to be clinically relevant based on the safety and efficacy of TDF plus LPV/r-containing regimens in HIV-infected patients in long-term controlled clinical trials.     

Analysis of Treatment Costs for HIV RNA Reductions and CD4 Increases for Darunavir Versus Other Antiretrovirals in Treatment-Experienced,HIV–Infected Patients

Abstract

Background: For patients with preexisting HIV drug resistance, a wide range of antiretrovirals are used, with differences in efficacy and cost. The additional cost per incremental 25 cell rise in CD4 count, or 0.5 log reduction in HIV RNA, was calculated for 8 antiretrovirals using pivotal clinical trials data. Method: For approved antiretrovirals in HIV therapy–experienced patients, 24–week efficacy (benefit over control in HIV RNA and CD4 count) was extracted from pivotal trials in published reports and compared with the additional treatment cost versus the control arm of each trial (2006 US wholesale acquisition costs). Treatment costs in the POWER trials were calculated directly from the treatment use database. Results: Data were available from 11 clinical trials in more than 4,000 antiretroviral treatment-experienced patients: Gilead 907 (TDF vs. placebo), TORO1/2 (T-20/OBR vs. OBR), RESIST–1/2 (TPV/r vs. control PI), BMS-045 (ATV/r vs. LPV/r), CONTEXT (fAPV/r vs. LPV/r), CAESAR (3TC vs. placebo), CNA3002 (ABC vs. placebo), and POWER 1/2 (DRV/r vs. control PI). Additional cost per 0.5 log reduction in HIV RNA was $152 for ritonavir–boosted darunavir (DRV/r), $4,453 for lamivudine (3TC), $4,274 for abacavir (ABC), $4,641 for tenofovir (TDF), and $13,217 for enfuvirtide (T-20). Cost per 25 cell rise in CD4 ranged from $132 for darunavir/r to $16,464 for T-20. Conclusion: There is a wide range of costs associated with efficacy improvements across the classes of antiretrovirals used for antiretroviral treatment–experienced patients. This analysis does not account for differences in toxicity, use of concomitant medications, or long-term adherence, which could also influence value assessments.     

Pharmacokinetics, safety, and efficacy of tipranavir boosted with ritonavir alone or in combination with other boosted protease inhibitors as part of optimized combination antiretroviral therapy in highly treatment-experienced patients (BI Study 1182.51)

BACKGROUND: Given the limited treatment options for patients with high-level resistance, antiretroviral (ARV) regimens based on concomitant use of 2 ritonavir (RTV)-boosted protease inhibitors (PIs) were considered a therapeutic option. METHODS: Boehringer Ingelheim (BI) study 1182.51 examined the pharmacokinetic profile, safety, and efficacy of RTV-boosted tipranavir (TPV/r), alone and in combination with comparator PIs (CPIs) in 315 triple-class-experienced, HIV-infected patients. RESULTS: Two weeks after single PI therapy, the addition of TPV/r reduced plasma trough levels 52%, 80%, and 56% for lopinavir (LPV), saquinavir (SQV), and amprenavir (APV) recipients, respectively. After 2 weeks, a TPV/r-only regimen reduced HIV viral load (VL) by a median of 1.06 log(10) copies/mL. VL reductions at 2 weeks between single-boosted CPIs were difficult to compare, because the numbers of patients maintaining their previous failing PI after randomization were different. At week 4, patients initiating treatment with TPV-containing regimens sustained VL reduction (median decrease of 1.27 log(10) copies/mL). Patients adding TPV to regimens at week 2 achieved median reductions from a baseline of 1.19 log(10), 0.96 log(10), and 1.12 log(10) copies/mL at week 4 in dual-boosted LPV, SQV, and APV groups, respectively. At 24 weeks, VL reductions (median: -0.24 to -0.47 log(10) copies/mL) were comparable between treatment groups. CONCLUSIONS: The efficacy of a dual PI regimen depended on the presence of TPV, with additional recycled CPIs having limited activity, even in drug-resistant patient populations with plasma trough concentrations regarded as likely to be adequate in this study. No clear guidelines exist about ARV plasma trough concentrations in treatment-experienced patients, however.     

Coadministration of lopinavir/ritonavir and phenytoin results in two-way drug interaction through cytochrome P-450 induction

Lopinavir/ritonavir (LPV/RTV) is a CYP3A4 inhibitor and substrate; it also may induce cytochrome P-450 (CYP) isozymes. Phenytoin (PHT) is a CYP3A4 inducer and CYP2C9/CYP2C19 substrate. This study quantified the pharmacokinetic (PK) drug interaction between LPV/RTV and PHT. Open-label, randomized, multiple-dose, PK study in healthy volunteers. Subjects in arm A (n = 12) received LPV/RTV 400/100 mg twice daily (BID) (days 1-10), followed by LPV/RTV 400/100 mg BID + PHT 300 mg once daily (QD) (days 11-22). Arm B (n = 12) received PHT 300 mg QD (days 1-11), followed by PHT 300 mg QD + LPV/RTV 400/100 mg BID (days 12-23). Plasma samples were collected on day 11 and day 22; PK parameters were compared by geometric mean ratio (GMR, day 22:day 11). P values <0.05 were considered significant. Following PHT addition, LPV area under the concentration-time curve (AUC0-12h) decreased from 70.9 +/-37.0 to 49.6 +/- 25.1 microg.h/mL (GMR 0.67, P = 0.011) and C0h decreased from 6.0 +/- 3.2 to 3.6 +/- 2.3 microg/mL (GMR 0.54, P = 0.001). Following LPV/RTV addition, PHT AUC0-24h decreased from 191.0+/-89.2 to 147.8+/-104.5 microg.h/mL (GMR 0.69, P = 0.009) and C0h decreased from 7.0+/-4.0 to 5.3+/-4.1 microg/mL (GMR 0.66, P = 0.033). Concomitant LPV/RTV and PHT use results in a 2-way drug interaction. Phenytoin appears to increase LPV clearance via CYP3A4 induction, which is not offset by the presence of low-dose RTV. LPV/RTV may increase PHT clearance via CYP2C9 induction. Management should be individualized to each patient; dosage or medication adjustments may be necessary.     

The use of drug resistance algorithms and genotypic inhibitory quotient in prediction of lopinavir-ritonavir treatment response in human immunodeficiency virus type 1 protease inhibitor-experienced patients.

BackgroundDifferent approaches using genotypic, pharmacokinetic parameters or combination of both have been recently developed to monitor antiretroviral treatment in HIV-1-infected individuals. Their uses in clinical practice may improve the benefit of protease inhibitor-based salvage therapy while reducing treatment toxicity and emergence of viral resistance.ObjectivesTo assess the prediction of genotypic inhibitory quotient (GIQ) using different genotypic drug resistance interpretation's algorithms and lopinavir plasma concentration in PI-experienced patients treated by lopinavir/ritonavir (LPV/r). Genotypic susceptibility score (GSS) was also evaluated.Study designForty-seven HIV-1 PI-experienced, but LPV naïve patients were included in a retrospective cohort study. Plasma HIV-1 viral load (VL), CD4 cell count and LPV plasma concentrations were assessed at weeks (W) 12 and 24. Interpretation of baseline resistance genotype was achieved according to four different algorithms and GSS calculated using two expert systems. GIQ was defined as the ratio of LPV concentration to the number of LPV resistance mutations at day 0 (D0) and patients classified by units of GIQ. The end point of the study was the virological response expressed in HIV VL median decrease from D0 to W24.ResultsThe overall median VL decrease from D0 to W24 was −2.42 log₁₀ copies/mL and 60% of patients had VL below 400 copies/mL. The LPV mutation score was predictive of response for all algorithms whereas plasma concentrations of LPV were not. Mean VL decrease was greater for higher GIQ classes and difference reached statistical significance at W24. When considering virological response at W24, GSS calculated with ANRS and Stanford system were good predictor scores as areas under the receiver operating characteristics (ROC) curves were 0.76 for both.ConclusionGIQ was found to be a useful drug-monitoring tool which could be helpful in targeting LPV concentrations in order to achieve long-term undetectable viral load, particularly in genotypic resistant patients.     

A Pilot,Prospective, Open-Label Simplification Study to Evaluate the Safety,Efficacy, and Pharmacokinetics of Once-Daily Lopinavir-Ritonavir Monotherapy in HIV-HCV Coinfected Patients: The MONOCO Study

Abstract

Background: A safe, effective, easy-to-dose antiretroviral therapy that minimizes hepatic complication risk is essential in optimizing HIV-HCV treatment. Nucleoside-sparing boosted protease inhibitor monotherapy may achieve this goal. Methods: A prospective, open-label pilot simplification study of once-daily lopina-vir/ritonavir (LPV/r) monotherapy in HIV-HCV coinfected patients was conducted in patients on HAART with undetectable HIV RNA for ≥6 months. The primary outcome was maintenance of HIV RNA <50 copies/mL through week 48. HIV RNA, immune measures, metabolic markers, and pharmacokinetics were assessed. Results: Twenty participants received once-daily LPV/r monotherapy. Mean baseline age was 46.9 years and CD4 467 cells/L. By per protocol analysis, 71.4% (95% CI, 45.4-88.3) remained on once-daily LPV/r monotherapy with virologic suppression at week 48. Virologic breakthrough (HIV RNA >50 copies/mL on 2 consecutive measures) occurred in 7 patients (mean standard error [SE] time to breakthrough, 38.3 [4.8] weeks). Resuppression occurred with improved adherence in 2 partici-pants and improved adherence plus addition of nucleosides in 2 others. LPV C ^min was <1 mg/L in 8 patients and was associated with virologic breakthrough in 2 cases but with no development of resistance. No clinically significant changes in CD4, lipids, or glucose were noted. Three participants developed transient ≥5-fold liver enzyme elevations. None of 9 severe adverse events were LPV/r- or liver-related. Six discontinued participation for withdrawal of consent (n=1), poor adherence (n=3), or drug intolerance (n=2). Conclusions: Once-daily LPV/r monotherapy in HIV-HCV coinfected individuals offers a safe and effective approach to the management of the HIV infection, with a predictable pharmacokinetic profile.     

Predictive factors of virologic success in HIV-1-infected children treated with lopinavir/ritonavir

Predictive factors of the virologic success of the use of lopinavir/ritonavir (LPV/r) in HIV-infected children are unknown, especially in children who have been pretreated with protease inhibitors (PIs). This longitudinal, single-center, observational study included 69 children (21 PI-naive and 48 PI-experienced) who had received LPV/r for at least 3 months. The mean (+/- SD) age was 10.3 +/- 4.8 years, and the mean baseline of CD4 percentage and HIV-1 RNA was 14.9% +/- 9.8% and 4.8 +/- 1.05 log10 copies/mL, respectively. The mean duration of follow-up was 16.5 +/- 8.3 months. At 6, 12, and 18 months, 52%, 57%, and 49% of all children, respectively, had a viral load less than 50 copies/mL. The risk of virologic failure, defined as 2 consecutive viral loads greater than 1000 copies/mL, was significantly higher when the children were previously treated with PIs and when the baseline LPV mutation score exceeded 3 mutations. In the pretreated children, the ratio of the plasma LPV maximal concentration to the baseline LPV score mutation was also associated with failure, independently of resistance score. Finally, in children failing an LPV-containing regimen, accumulation of additional PI-associated resistance mutations was evidenced in viral isolates from children with prior PI treatment, even with viral replication levels less than 10,000 copies/mL. In pretreated children, LPV plasma levels should be optimized in an attempt to achieve sufficient drug concentrations to overcome the resistance level.     

Initial therapy of HIV infection.

BACKGROUND: The use of antiretroviral therapy has improved the quality of life and has increased the survival of HIV-infected individuals. However, the rapid rate of virus mutation and subsequent emergence of drug-resistant HIV variants threaten the longer-term efficacy of HIV treatment. The initial regimen provides the greatest chance for lasting suppression of viral load. AIMS: Appropriate selection of the initial antiretroviral regimen is critical. The growing number of drug classes allows healthcare providers to individualize treatment regimens. Factors influencing the selection of first-line therapy include baseline viral load and CD4 count, drug pharmacokinetics, potency, tolerability, safety, resistance and salvageability. Characteristics likely to affect adherence, such as regimen complexity and pill burden, must also be considered, as poor adherence is the most common cause of treatment failure. CONCLUSION: The selection of the initial regimen requires consideration of several factors. Drugs from new classes as well as new drugs from existing classes with favorable resistance and side effect profiles are in various stages of development. Many of these drugs will enhance available options for initial therapy.     

Efficacy and safety of atazanavir, with or without ritonavir, as part of once-daily highly active antiretroviral therapy regimens in antiretroviral-naive patients

BACKGROUND: Atazanavir (ATV), the first once-daily protease inhibitor approved for the treatment of HIV-1 infection, is recommended for use in antiretroviral (ARV) treatment-naive and -experienced patients. Study AI424-089 was a prospective, randomized, open-label, 96-week study comparing 2 ATV-based treatment regimens in ARV-naive HIV-infected patients. METHODS: Adults with HIV RNA levels > or =2000 copies/mL were randomized (1:1) to once-daily ATV at a dose of 300 mg with ritonavir at a dose of 100 mg (ATV300/RTV) or ATV at a dose of 400 mg (ATV400); both regimens included lamivudine and an investigational extended-release formulation of stavudine. The primary endpoint for this noninferiority study was the proportion of patients (response rate) with an HIV RNA load <400 copies/mL at week 48. RESULTS: Response rates at week 48 were 86% and 85% on the ATV300/RTV and ATV400 regimens, respectively (difference estimate [95% confidence interval] = 1.5 [-8.2 to 11.1]). There were 3 and 10 patients with virologic failure in the ATV300/RTV and ATV400 groups, respectively. One patient (ATV400) developed phenotypic resistance to ATV associated with an I50L substitution. Adverse event-related discontinuations were 8% among ATV300/RTV-treated patients and <1% among ATV400-treated patients. Plasma lipid elevations were low with both regimens. Both regimens were well tolerated. CONCLUSIONS: These findings demonstrate the safety and efficacy of the ATV300/RTV regimen and confirm the safety and efficacy of ATV400 in an ARV-naive patient population.     

An Italian approach to postmarketing monitoring: preliminary results from the SCOLTA (Surveillance Cohort Long-Term Toxicity Antiretrovirals) project on the safety of lopinavir/ritonavir

The SCOLTA project (Surveillance Cohort Long-term Toxicity Antiretrovirals) is a system for online surveying of adverse reactions to recently commercialized antiretroviral drugs and a "sentinel" for unexpected and late adverse reactions arising during any antiretroviral treatment (available at: http://www.cisai.info). To date, 25 Italian departments of infectious diseases have participated at the project. The New Drugs Project is a prospective, multicenter, observational pharmacovigilance study involving 1 cohort of patients for each new drug. All patients who were consecutively started on lopinavir (LPV), tenofovir (TDF), peginterferon (IFN), atazanavir (ATZ), enfuvirtide (T-20), and tipranavir (TPV) were enrolled. All grade III or IV adverse events (according to the AIDS Clinical Trials Group definitions) are reported on the web site. The Unexpected Events Project identifies unexpected adverse reactions during treatment and reports them. This paper presents the preliminary findings for the New Drugs Project. Between October 1, 2002, and March 30, 2004, 1184 patients were enrolled. The lopinavir/ritonavir (LPV/r) cohort comprises 703 patients, the TDF cohort 585, IFN 35, ATZ 95, T-20 10, and TPV 8. So far 100 grades III and IV adverse events have been reported, 73 in the LPV/r group. In this cohort the rate of adverse events per 100 person-years was 14.2 on the basis of all patients treated, 9.8 for treatment-naive patients, and 15 for treatment-experienced patients. These findings, though preliminary, show that this data collection method gives timely real-life information from which to assess the impact of short- and long-term toxicity of new antiretroviral drugs.     

The impact of highly active antiretroviral therapy by the oral route on the CD8 subset in monkeys infected chronically with SHIV 89.6P

The objective of this study was to assess the impact of highly active antiretroviral therapy (HAART) by an oral route on the peripheral blood CD8 subset in the monkeys infected persistently with a pathogenic strain, SHIV(89.6P). Two rhesus macaques were inoculated intravenously with SHIV(89.6P), then treated with the combination of AZT, 3TC and Lopinavir/Ritonavir (LPV/RTV) as recommended in humans by the oral route with confectionery continued for 28 days. In one of two chronically infected macaques, MM260, the viral load was maintained in the range of 10(4)-10(5) copies/ml before HAART. The plasma viral load and proviral DNA decreased dramatically during the treatment, and cessation of this therapy the viral load rebounded to the pre-treatment level but the proviral DNA rebound was delayed. The other monkey, MM242, had low viral loads (1.2x10(3)-<5x10(2) copies/ml) both before and after HAART. CD4(+) and CD8(+) T cell counts and proviral DNA level were not significantly changed after the treatment. The percentages of CD8(+)CD45RA(-)Ki67(+)cells increased during (MM260) or after (MM242) HAART and the subset was maintained at a high percentage until 18 weeks post HAART in MM242. These findings suggest that this primate model might serve an important role in testing the virological and immunological efficacy of novel therapeutic strategies combined with HAART.     

Impaired CD4+ cell recovery during antiretroviral therapy in patients with HIV resistance mutations

Antiretroviral therapy is limited by the development of human immunodeficiency virus (HIV) resistance mutations. Although resistance testing is recommended during therapy failure, little is known about the optimal time points for testing or its impact on treatment. In this study, we investigated HIV polymorphisms and mutations and assessed their influence on the outcome of highly active antiretroviral therapy (HAART). We focused on viral load and CD4+ cell counts as the most important parameters for therapy response. Resistance mutations were present in 19% of all patients prior to antiretroviral treatment. Mutations causing direct antiretroviral drug resistance were observed in 10%. Analyzing therapy response, we found a significant correlation between resistance mutations and impaired CD4+ cell recovery six months after the initiation of antiretroviral treatment. Lower CD4+  cell counts were also observed in a subgroup of patients infected with a virus presenting mutations that directly lowered drug susceptibility.     

Lopinavir/ritonavir plus nevirapine as a nucleoside-sparing approach in antiretroviral-experienced patients (NEKA study)

OBJECTIVES: To compare the efficacy and safety of a nucleoside-sparing approach with a conventional highly active antiretroviral therapy (HAART) regimen in antiretroviral-experienced patients with prolonged viral suppression. METHODS: Pilot study including 31 antiretroviral-experienced patients with HIV RNA <80 copies/mL. Subjects were randomly assigned to lopinavir/ritonavir (LPV/rtv) 400/100 mg BID plus nevirapine (NVP) 200 mg BID (NVP group, n = 16) or LPV/rtv plus the 2 previous NRTIs (NRTI group, n = 15). The primary endpoint was the percentage of subjects who maintained viral suppression at week 48. Changes in lipid metabolism, mitochondrial parameters, and LPV trough levels were also assessed. RESULTS: All patients maintained viral suppression after 48 weeks. No subject discontinued therapy because of adverse events. HDL cholesterol increased by 28% at week 24 (P < 0.0001) and 10% after 48 weeks of follow-up (P = 0.319) in the NVP group. In the NRTI group, LDL cholesterol increased by 14% at week 48 (P = 0.076). Mitochondrial DNA/nuclear DNA ratio and mitochondrial respiratory chain complex IV activity showed a trend toward increasing in the NVP group. Mean (SD) LPV trough levels were 6340 (2129) ng/mL in the NRTI group and 5161 (2703) ng/mL in the NVP group (P = 0.140). CONCLUSIONS: In antiretroviral-experienced subjects with sustained viral suppression, dual therapy with NVP plus LPV/rtv at standard dosage was as potent and safe as standard-of-care HAART at 48 weeks of follow-up. This approach may reduce mitochondrial toxicity and improve LPV/rtv-associated lipid abnormalities. The results of this pilot study support the study of this approach in a larger, randomized trial.