Efficacy, safety and predictive factors of virological success of a boosted amprenavir-based salvage regimen in heavily antiretroviral-experienced HIV-1-infected patients

Virologic and Immunologic Outcomes of the Second-Line Regimens of Antiretroviral Therapy Among HIV-Infected Patients in Thailand

Goal of the second-line therapy among HIV-1-infected patients is to re-establish virological suppression, although treatment options in resource-limited settings are limited. An observational cohort of patients with first-line antiretroviral therapy (ART) failure was conducted in a university hospital in Thailand. Of 95 patients, mean age 39 years, 65% were male. Median CD4 and HIV-1 RNA at second-line ART initiation were 158 cells/mm(3) and 4.1 copies/mL, respectively. Boosted protease inhibitor plus 2 nucleoside reverse transcriptase inhibitors (NRTIs), indicated by genotype results, was commonly used as second-line regimen. At 6, 12, 24, and 36 months of second-line ART, 67%, 62%, 84%, and 90% of patients achieved HIV-1 RNA <50 copies/mL; median CD4 were 258, 366, 444, and 522 cells/mm( 3), respectively. Good adherence, high baseline CD4, and early Centers for Centers for Disease Control and Prevention (CDC) staging were associated with virologic success (P < .05). Second-line ART based on the results of genotype testing yields the good virologic and immunologic outcomes in a resource-limited setting, and scaling-up of second-line ART is indicated.

Salvage Therapy with Ritonavir-Boosted Amprenavir/Fosamprenavir: Virological and Immunological Response in Two Years Follow-up

OBJECTIVE

To evaluate the efficacy of salvage regimens containing ritonavir-boosted amprenavir (APV/r) or fosamprenavir (FPV/r) in heavily pretreated protease inhibitor (PI)-experienced HIV-1 patients.

METHOD

Evaluation of APV/r- or FPV/r-containing antiretroviral regimens in PI-experienced HIV-1 patients with 2 or more antiretroviral failures. Follow-up continued to 96 weeks with prospective collection of data.

RESULTS

54 episodes (48 on APV/r and 6 on FPV/r) were considered in 45 patients who had received a median of 5 prior antiretroviral regimens (range, 2-13) including a median of 3 PIs (range, 2-4). Median time of treatment at analysis was 72 weeks (range, 12-210). At baseline, plasma viral load (pVL) and CD4 cell count was 67,000 copies/mL and 167 cell/mm(3), respectively. At week 96, the median pVL was < 50 copies/mL and CD4 cell count was 519 cells/mm(3). Proportion of patients with pVL below detection was 62% at week 48 and 61% at week 96. Fifteen patients stopped treatment because of virologic failure; one presented a full resistance profile to APV/r, based on the ANRS 2003 resistance algorithm. Median trough APV plasma concentration 4 weeks after treatment initiation was 1406 ng/mL (range, 452-4321); dose adaptation was required in only 7 patients.

CONCLUSION

This study provides long-term follow-up of APV/r and FPV/r in the setting of salvage therapy, showing a high and sustained rate of virologic and immunologic response.

Predictive value of pharmacokinetics-adjusted phenotypic susceptibility on response to ritonavir-enhanced protease inhibitors (PIs) in human immunodeficiency virus-infected subjects failing prior PI therapy

The activities of protease inhibitors in vivo may depend on plasma concentrations and viral susceptibility. This nonrandomized, open-label study evaluated the relationship of the inhibitory quotient (IQ [the ratio of drug exposure to viral phenotypic susceptibility]) to the human immunodeficiency virus type 1 (HIV-1) viral load (VL) change for ritonavir-enhanced protease inhibitors (PIs). Subjects on PI-based regimens replaced their PIs with ritonavir-enhanced indinavir (IDV/r) 800/200 mg, fosamprenavir (FPV/r) 700/100 mg, or lopinavir (LPV/r) 400/200 mg twice daily. Pharmacokinetics were assessed at day 14; follow-up lasted 24 weeks. Associations between IQ and VL changes were examined. Fifty-three subjects enrolled, 12 on IDV/r, 33 on FPV/r, and 8 on LPV/r. Median changes (n-fold) (FC) of 50% inhibitory concentrations (IC(50)s) to the study PI were high. Median 2-week VL changes were -0.7, -0.1, and -1.0 log(10) for IDV/r, FPV/r, and LPV/r. With FPV/r, correlations between the IQ and the 2-week change in VL were significant (Spearman's r range, -0.39 to -0.50; P < or = 0.029). The strongest correlation with response to FPV/r was the IC(50) FC (r = 0.57; P = 0.001), which improved when only adherent subjects were included (r = 0.68; P = 0.001). In multivariable analyses of the FPV/r arm that included FC, one measure of the drug concentration, corresponding IQ, baseline VL, and CD4, the FC to FPV was the only significant predictor of VL decline (P < 0.001). In exploratory analyses of all arms, the area under the concentration-time curve IQ was correlated with the week 2 VL change (r = -0.72; P < 0.001). In conclusion, in PI-experienced subjects with highly resistant HIV-1, short-term VL responses to RTV-enhanced FPV/r correlated best with baseline susceptibility. The IQ improved correlation in analyses of all arms where a greater range of virologic responses was observed.

Protease inhibitor levels in hair strongly predict virologic response to treatment

OBJECTIVE

Antiretroviral (ARV) therapies fail when behavioral or biologic factors lead to inadequate medication exposure. The currently available methods to assess ARV exposure are limited. Levels of ARVs in hair reflect plasma concentrations over weeks to months, and may provide a novel method for predicting therapeutic responses.

DESIGN/METHODS

The Women's Interagency HIV Study, a prospective cohort of HIV-infected women, provided the basis for developing and assessing methods to measure commonly prescribed protease inhibitors (lopinavir/ritonavir and atazanavir) in small hair samples. We examined the association between hair protease inhibitor levels and initial virologic responses to therapy in multivariate logistic regression models.

RESULTS

ARV concentrations in hair were strongly and independently associated with treatment response for 224 women starting a new protease inhibitor-based regimen. For participants initiating lopinavir/ritonavir, the odds ratio (OR) for virologic suppression was 39.8 [95% confidence interval (CI) = 2.8-564] for those with lopinavir hair levels in the top tertile (>1.9 ng/mg) compared to the bottom (3.4 ng/mg) compared to the lowest (

CONCLUSION

Protease inhibitor levels in small hair samples were the strongest independent predictor of virologic success in a diverse group of HIV-infected adults. This non-invasive method for determining ARV exposure may have particular relevance for the epidemic in resource-poor settings due to the ease of collecting and storing hair.

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Key Words

• hair levels
• therapeutic drug monitoring
• antiretroviral exposure
• virologic response
• protease inhibitors
• atazanavir
• lopinavir
• wihs cohort

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MESH Headings

• Adult
• Atazanavir Sulfate
• CD4 Lymphocyte Count
• Drug Monitoring/methods
• Epidemiologic Methods
• Female
• HIV Infections/drug therapy
• HIV Infections/metabolism
• HIV Infections/virology
• HIV Protease Inhibitors/pharmacokinetics
• HIV Protease Inhibitors/therapeutic use
• Hair/metabolism
• Humans
• Lopinavir
• Middle Aged
• Oligopeptides/pharmacokinetics
• Oligopeptides/therapeutic use
• Patient Compliance
• Pyridines/pharmacokinetics
• Pyridines/therapeutic use
• Pyrimidinones/pharmacokinetics
• Pyrimidinones/therapeutic use
• Ritonavir/pharmacokinetics
• Ritonavir/therapeutic use
• Specimen Handling/methods
• Treatment Outcome
• Viral Load

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Grants

• M01 RR000079 NCRR NIH HHS
• UO1-AI-34994 NIAID NIH HHS
• UO1-AI-34989 NIAID NIH HHS
• U01 AI035004 NIAID NIH HHS
• K23 AI067065 NIAID NIH HHS
• UO1-CH-32632 OID CDC HHS
• U01 AI034989 NIAID NIH HHS
• M01 RR000071 NCRR NIH HHS
• UO1-AI-34993 NIAID NIH HHS
• U01 AI034994 NIAID NIH HHS
• K23 AI067065-03 NIAID NIH HHS
• UO1-AI-42590 NIAID NIH HHS
• U01 AI034993 NIAID NIH HHS
• K23 A1067065 PHS HHS
• MO1-RR-00083 NCRR NIH HHS
• U01 AI031834 NIAID NIH HHS
• UO1-AI-35004 NIAID NIH HHS
• K23 AI067065-02 NIAID NIH HHS
• U01 AI042590-12 NIAID NIH HHS
• MO1-RR-00079 NCRR NIH HHS
• UO1-AI-31834 NIAID NIH HHS
• M01 RR000083 NCRR NIH HHS
• MO1-RR-00071 NCRR NIH HHS
• U01 AI042590 NIAID NIH HHS

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Affiliation(s)

Monica Gandhi Department of Medicine, University of California, San Francisco, San Francisco, California, USA.
Niloufar Ameli
Peter Bacchetti
Stephen J Gange
Kathryn Anastos
Alexandra Levine
Charles L Hyman
Mardge Cohen
Mary Young
Yong Huang
Ruth M Greenblatt

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Predictive values of the human immunodeficiency virus phenotype and genotype and of amprenavir and lopinavir inhibitory quotients in heavily pretreated patients on a ritonavir-boosted dual-protease-inhibitor regimen

The inhibitory quotient (IQ) of human immunodeficiency virus (HIV) protease inhibitors (PIs), which is the ratio of drug concentration to viral susceptibility, is considered to be predictive of the virological response. We used several approaches to calculate the IQs of amprenavir and lopinavir in a subset of heavily pretreated patients participating in the French National Agency for AIDS Research (ANRS) 104 trial and then compared their potentials for predicting changes in the plasma HIV RNA level. Thirty-seven patients were randomly assigned to receive either amprenavir (600 mg twice a day [BID]) or lopinavir (400 mg BID) plus ritonavir (100 or 200 mg BID) for 2 weeks before combining the two PIs. The 90% inhibitory concentration (IC(90)) was measured using a recombinant assay without or with additional human serum (IC(90+serum)). Total and unbound PI concentrations in plasma were measured. Univariate linear regression was used to estimate the relation between the change in viral load and the IC(90) or IQ values. The amprenavir phenotypic IQ values were very similar when measured with the standard and protein binding-adjusted IC(90)s. No relationship was found between the viral load decline and the lopinavir IQ. During combination therapy, the amprenavir and lopinavir genotypic IQ values were predictive of the viral response at week 6 (P = 0.03). The number of protease mutations (< 5 or > or = 5) was related to the virological response throughout the study. These findings suggest that the combined genotypic IQ and the number of protease mutations are the best predictors of virological response. High amprenavir and lopinavir concentrations in these patients might explain why plasma concentrations and the phenotypic IQ have poor predictive value.

Genotypic resistance to lopinavir and fosamprenavir with or without ritonavir of clinical isolates from patients failing protease inhibitors-containing HAART regimens: prevalence and predictors

The aim of this study was to establish the prevalence and predictors of genotypic resistance of HIV-1 to lopinavir and fosamprenavir from patients failing protease inhibitors (PI)-based regimens. We selected 643 HIV-1-infected patients with available treatment history who underwent genotypic resistance assays for virological failure from a clinical site and from the Stanford database. According to the genotypic resistance interpretation of the Stanford algorithm, proportions of viruses showing full susceptibility to fosamprenavir and lopinavir were 32% and 34%, respectively (p =ns). Proportions of viruses fully susceptible to lopinavir/r and fosamprenavir/r according to the Agence Nationale pour la Recherche sur le SIDA (ANRS) algorithm, were 81% and 81%, respectively. According to the Rega algorithm, proportions of viruses showing full susceptibility to fosamprenavir/r and lopinavir were 80% and 70%, respectively (p<0.001). According to the ANRS and Rega interpretations, the time on therapy predicted susceptibility to lopinavir/r, while susceptibility to fosamprenavir/r according to ANRS was predicted by the number of prior PI regimens experienced. According to the Stanford interpretation, prior indinavir exposure predicted resistance to lopinavir/r and fosamprenavir/r while prior nelfinavir use predicted susceptibility to both drugs. After failing PI-based regimens, the majority of viruses retained a predicted susceptibility to fosamprenavir/r and lopinavir/r. In patients failing PIs, the interpretation of genotypic resistance to fosamprenavir may change considerably according to the different algorithms and in respect to the effect of pharmacokinetic boosting with ritonavir.