Carmelita Alvero

Efavirenz pharmacokinetics in HIV-1-infected children are associated with CYP2B6-G516T polymorphism

Background:The CYP2B6-G516T polymorphism has been shown to alter plasma efavirenz (EFV) concentrations in adults. The impact of CYP2B6-G516T polymorphisms on EFV concentrations may be different in children because of differences in liver maturation and drug dosage. Methods:The CYP2B6-G516T polymorphisms were analyzed in 71 HIV-1-infected children receiving highly active antiretroviral therapy (HAART) containing EFV for ≥6 months. EFV pharmacokinetics, toxicity profiles, and viral resistance data were also evaluated. Results:The median oral clearance (CL/F) rate was significantly lower in children with the CYP2B6-516-T/T genotype (3.0 L/h/m2, n = 13) than in children with the G/T genotype (5.7 L/h/m2, n = 30; P = 0.02) or the G/G genotype (7.0 L/h/m2, n = 31; P = 0.003). In children with the CYP2B6-516-G/G genotype, which is associated with higher expression of hepatic CYP2B6, the clearance rate was significantly higher in younger children (<5 years of age) than in older children (≥5 years of age) (9.7 L/h/m2 vs. 6.6 L/h/m2; P = 0.03). No association was found between CYP2B6-G516T polymorphisms and virologic or immunologic responses, toxicity, or the development of viral resistance against EFV. Conclusions:CYP2B6-G516T polymorphisms significantly affect the CL/F rate of EFV in children. Changes in hepatic enzyme activity by age may need to be considered when evaluating the impact of genetic variants on antiretroviral pharmacokinetics in children.

Dynamics of the resting CD4(+) T-cell latent HIV reservoir in infants initiating HAART less than 6 months of age.

Objectives:Identification of HIV infection in exposed infants facilitates early therapy, which may limit viral reservoirs that maintain HIV infection under HAART. Methods:The dynamics of the resting CD4+ T-cell latent HIV reservoir was determined over the first 2 years of life in 17 HIV-infected infants initiating lopinavir/ritonavir-based HAART at a median age of 8.1 weeks and achieving adequate suppression of plasma viral load by 24 weeks. Results:The resting CD4+ T-cell latent HIV reservoir was detected in 12 of 14 (86%) infants tested at 24 weeks of HAART [median frequency 1.88 infectious units per million (IUPM); range <0.22 to 81.7), and remained measurable (median IUPM = 0.32; range <0.22 to 3.25) in six of 10 (60%) children retested at 96 weeks. The reservoir declined, from 24 to 96 weeks of HAART, at an estimated mean rate of 0.028 log10 IUPM/month, corresponding to a half-life of 11 months (95% confidence interval 6–30 months]. A strong relationship was found between the frequency of latently infected CD4+ T cells at 96 weeks of HAART and time to first undetectable plasma viral load (Spearman r = 0.91, P < 0.001). Conclusion:Although the resting CD4+ T-cell latent reservoir remains detectable over the first 2 years of HAART in a substantial proportion of infants, its size is associated with time to first undetectable viral load. To minimize HIV reservoirs in infants, rapid curtailment of viremia may limit HIV reservoirs and should be a therapeutic goal of early HAART in infants.

Lipid and Glucose Alterations in HIV-Infected Children Beginning or Changing Antiretroviral Therapy

OBJECTIVE. The objective of this study was to describe lipid profiles and glucose homeostasis in HIV-positive children after initiating or changing antiretroviral therapy and their associations with viral, immune, antiretroviral therapy, and growth factor parameters. METHODS. Ninety-seven prepubertal HIV-positive children aged 1 month to <13 years were observed for 48 weeks after beginning or changing antiretroviral therapy. Fasting lipid panels, serum glucose, insulin, insulin-like growth factor-1 and binding proteins-1 and -3, plasma viral load, and CD4% were measured. Each child was matched on age, gender, and race/ethnicity to children from the National Health and Nutrition Examination Survey, used to give z scores for each childs lipid values. Multivariate regression was used to evaluate the association of changes in z scores over 48 weeks with suppression of HIV-1 RNA, change in CD4% and growth factors, and antiretroviral therapy, adjusted for entry z score, CD4%, log10 HIV-1 RNA, Centers for Disease Control and Prevention category, and total fat and cholesterol dietary intake. RESULTS. Lipid, apolipoprotein, and insulin levels all increased significantly by 48 weeks. Multivariate analysis of changes demonstrated that increased HDL and decreased total-HDL cholesterol ratio were associated with CD4% increase and with insulin-like growth factor-1, which increased to normal (versus remained stable or became low) over 48 weeks. Total cholesterol levels increased among children who achieved HIV-1 RNA of <400 copies per mL. Antiretroviral therapy regimens that included both a protease inhibitor and a non–nucleoside reverse transcriptase inhibitor were associated with greater increases in total-HDL cholesterol ratio than regimens that contained a protease inhibitor or a non–nucleoside reverse transcriptase inhibitor but not both. CONCLUSIONS. In these HIV-positive children with predominantly mild-to-moderate disease, initiation or change in antiretroviral therapy was associated with significant increases in multiple lipid measures and insulin resistance. Favorable lipid changes were associated with CD4% increases, suggesting a protective effect of immune reconstitution on atherosclerosis, and with increased insulin-like growth factor-1 levels, supporting the theory that reduced growth hormone resistance may be a mechanism by which lipid profiles are improved. Finally, antiretroviral therapy regimens that contain both a non–nucleoside reverse transcriptase inhibitor and a protease inhibitor are associated with worse lipid profiles than regimens that contain 1 but not both of these drug classes.

Early Initiation of Lopinavir/Ritonavir in Infants Less Than 6 Weeks of Age: Pharmacokinetics and 24 Week Safety and Efficacy

Background: With increasing recognition of the benefits of early antiretroviral therapy initiation in perinatally HIV-infected infants, data are needed regarding the pharmacokinetics (PK), safety, and efficacy of recommended first-line protease inhibitors such as lopinavir/ritonavir (LPV/r). Methods: A prospective, phase I/II, open-label, dose-finding trial evaluated LPV/r at a dose of 300/75 mg/m2 twice daily plus 2 nucleoside analogs in HIV-1-infected infants ≥14 days to <6 weeks of age. Intensive 12-hour PK evaluations were performed after 2 weeks of LPV/r therapy, and doses were modified to maintain LPV predose concentrations >1 μg/mL and area under the curve (AUC) <170 μg hr/mL. Results: Ten infants enrolled [median age 5.7 (range, 3.6–5.9) weeks] with median HIV-1 RNA of 6.0 (range, 4.7–7.2) log10 copies/mL; all completed 24 weeks of follow-up. Nine completed the intensive PK evaluation at a median LPV dose of 267 (range, 246–305) mg/m2 q12 hours; median measures were AUC = 36.6 (range, 27.9–62.6) μg hr/mL; predose concentration = 2.2 (range, 0.99–4.9) μg/mL; maximum concentration = 4.76 (range, 2.84–7.28) μg/mL and apparent clearance (L/h/m2) = 6.75 (range, 2.79–12.83). Adverse events were limited to transient grade 3 neutropenia in 3 subjects. By week 24, 2 of 10 subjects had experienced a protocol-defined virologic failure. Conclusions: Although the LPV AUC in this population was significantly lower than that observed in infants ages 6 weeks to 6 months, LPV/r-based antiretroviral therapy in doses of 300/75 mg/m2 BID was well tolerated and resulted in virologic control in 8 of 10 infants by 24 weeks. Additional investigation is needed to understand the long-term implications of the lower LPV exposure in this age group.

Impact of Nucleoside Reverse Transcriptase Inhibitors on Mitochondria in Human Immunodeficiency Virus Type 1-Infected Children Receiving Highly Active Antiretroviral Therapy

ABSTRACT Mitochondrial toxicity induced by nucleoside reverse transcriptase inhibitors (NRTIs) has been reported to be responsible for various adverse effects. The relative impact of NRTIs on the mitochondria of human immunodeficiency virus (HIV) type 1 (HIV-1)-infected children receiving highly active antiretroviral therapy (HAART) is unknown. Mitochondrial DNA (mtDNA) levels were quantified longitudinally from peripheral blood mononuclear cells (PBMCs) in 31 HIV-1-infected children from Pediatric AIDS Clinical Trial Group Study 382 who were receiving HAART, including nelfinavir, efavirenz, and different NRTIs, and who had had undetectable plasma HIV-1 RNA levels for >2 years. The median mtDNA levels in PBMCs increased from 137 copies/cell at the baseline to 179 copies/cell at week 48 (P = 0.01) and 198 copies/cell at week 104 (P < 0.001). Before the initiation of HAART, children who received regimens containing didanosine had mtDNA levels persistently lower than those in children not receiving didanosine (106 versus 140 copies/cell; P = 0.008). During HAART, the median increase in the mtDNA level from the baseline to week 104 was the lowest in children who received regimens containing didanosine (+26 copies/cell) compared to those in children who received other regimens (+79 copies/cell) (P = 0.02). A multivariate analysis also demonstrated that didanosine, as part of HAART, was the only NRTI associated with the change in mtDNA levels (P = 0.007). Children receiving didanosine-containing antiretroviral regimens have the lowest mtDNA levels in PBMCs and may be at greater risk for long-term adverse effects due to mitochondrial toxicity. This may be of particular importance in resource-limited countries where didanosine is widely used for the treatment of HIV-infected children.

Pharmacokinetics and Pharmacodynamics of Efavirenz and Nelfinavir in HIV‐infected Children Participating in an Area‐under‐the‐curve Controlled Trial

Fifty human immunodeficiency virus (HIV)‐infected children participated in an area‐under‐the plasma concentration–time curve (AUC)‐controlled trial of efavirenz and nelfinavir. Pharmacokinetic evaluations were performed at weeks 2, 6, and 56. Efavirenz and nelfinavir doses were adjusted to achieve AUC values of 60–120 and ⩾10 mg h/l, respectively. Thirty‐seven (74%) children met the efavirenz target and 41 (82%) the nelfinavir by week 10. Children with AUC values for both drugs above the first quartile were more likely to reach <400 copies/ml of HIV RNA at week 8. Efavirenz and nelfinavir oral clearance increased 37 and 62% from weeks 2 to 56, respectively, in 34 children who continued on therapy at week 56. AUC values at week 56 were not different between children who did or did not have HIV RNA <400 copies/ml. Dose adjustment to achieve specific AUC values in these children reduced the risk of suboptimal exposure and achieved high rates of virologic suppression.

Long-term outcomes for HIV-infected infants less than 6 months of age at initiation of lopinavir/ritonavir combination antiretroviral therapy

Objective:To investigate the longitudinal pharmacokinetics, safety and efficacy of lopinavir/ritonavir (LPV/r) in HIV-infected infants initiating combination antiretroviral therapy (cART) between 2 weeks and 6 months of age. Method:A prospective, open-label, multicenter Phase I/II study of LPV/r-based cART at a dose of 300/75 mg/m2/dose LPV/r twice daily. Intensive pharmacokinetic sampling at 12 months of age and quarterly predose LPV concentrations were collected and safety, virologic and immunologic responses were monitored every 4–12 weeks up to 252 weeks. Results:Thirty-one HIV-infected infants enrolled into two age cohorts, 14 days to <6 weeks and 6 weeks to <6 months; 29 completed ≥48 weeks of follow-up (median = 123 weeks, range 4–252). At 12 months of age, median LPV area under the curve was comparable for both age cohorts and similar to older children and adults. At week 48, 22 of 31 patients (71%) had HIV-1 RNA <400 copies/ml and 11 of 15 (73%) had <50 copies/ml; 29 of 31 achieved HIV-1 RNA <400 copies/ml on study treatment and 19 (66%) remained durably suppressed until the end of study; viral suppression correlated with a higher percentage of predose time points exceeding the LPV target of 1 μg/ml (92 vs. 71%, P = 0.002). Conclusion:LPV/r at 300/75 mg/m2/dose as part of a cART regimen resulted in viral suppression through 96 weeks of treatment in >65% of young infants. Due to initially low LPV exposure in infants <6 weeks of age, frequent dose adjustment for weight gain is advisable and consideration should be given to studying a higher dose for very young infants.

Pharmacokinetics of High-Dose Lopinavir-Ritonavir with and without Saquinavir or Nonnucleoside Reverse Transcriptase Inhibitors in Human Immunodeficiency Virus-Infected Pediatric and Adolescent Patients Previously Treated with Protease Inhibitors

ABSTRACT Human immunodeficiency virus (HIV)-infected children and adolescents who are failing antiretrovirals may have a better virologic response when drug exposures are increased, using higher protease inhibitor doses or ritonavir boosting. We studied the pharmacokinetics and safety of high-dose lopinavir-ritonavir (LPV/r) in treatment-experienced patients, using an LPV/r dose of 400/100 mg/m2 orally every 12 h (p.o. q12h) (without nonnucleoside reverse transcriptase inhibitor [NNRTI]), or 480/120 mg/m2 p.o. q12h (with NNRTI). We calculated the LPV inhibitory quotient (IQ), and when the IQ was <15, saquinavir (SQV) 750 mg/m2 p.o. q12h was added to the regimen. We studied 26 HIV-infected patients. The median age was 15 years (range, 7 to 17), with 11.5 prior antiretroviral medications, 197 CD4 cells/ml, viral load of 75,577 copies/ml, and a 133-fold change in LPV resistance. By treatment week 2, 14 patients had a viral-load decrease of >0.75 log10, with a median maximal decrease in viral load of −1.57 log10 copies/ml at week 8. At week 2, 19 subjects showed a median LPV area under the concentration-time curve (AUC) of 157.2 (range, 62.8 to 305.5) μg·h/ml and median LPV trough concentration (Ctrough) of 10.8 (range, 4.1 to 25.3) μg/ml. In 16 subjects with SQV added, the SQV median AUC was 33.7 (range, 4.4 to 76.5) μg·h/ml and the median SQV Ctrough was 2.1 (range, 0.2 to 4.1) μg/ml. At week 24, 18 of 26 (69%) subjects remained in the study. Between weeks 24 and 48, one subject withdrew for nonadherence and nine withdrew for persistently high virus load. In antiretroviral-experienced children and adolescents with HIV, high doses of LPV/r with or without SQV offer safe options for salvage therapy, but the modest virologic response and the challenge of adherence to a regimen with a high pill burden may limit the usefulness of this approach.

Safety, Pharmacokinetics and Efficacy of Dolutegravir in Treatment-experienced HIV-1 Infected Adolescents: Forty-eight-week Results from IMPAACT P1093.

Objective: To assess the pharmacokinetics (PK), safety and efficacy of dolutegravir plus optimized background regimen in HIV-infected treatment-experienced adolescents. Methods: Children older than 12 to younger than 18 years received dolutegravir weight-based fixed doses at approximately 1.0 mg/kg once daily in a phase I/II multicenter open label 48-week study. Intensive PK evaluation was done at steady state after dolutegravir was added to a failing regimen or started at the end of a treatment interruption. Safety and HIV RNA and CD4 cell count assessments were performed through week 48. Results: Twenty-three adolescents were enrolled and 22 (96%) completed the 48-week study visit. Median age and weight were 15 years and 52 kg, respectively. Median [interquartile range (IQR)] baseline CD4+ cell count was 466 cells/&mgr;L (297, 771). Median (IQR) baseline HIV-1 RNA log10 was 4.3 log10 copies/mL (3.9, 4.6). Dolutegravir geometric mean of the area under the plasma concentration–time curve from time of administration to 24 hours after dosing (AUC0–24) and 24 hour postdose concentration (C24) were 46.0 &mgr;g hours/mL and 0.90 &mgr;g/mL, respectively, which were within the study targets based on adult PK ranges. Virologic success with an HIV RNA <400 copies/mL was achieved in 74% [95% confidence interval (CI): 52–90%] at week 48. Additionally, 61% (95% CI: 39–80%) had an HIV RNA <50 copies/mL at week 48. Median (IQR) gain in CD4 cell count at week 48 was 84 cells/&mgr;L (−81, 238). Dolutegravir was well tolerated, with no grade 4 adverse events, serious adverse events or discontinuations because of serious adverse events. Conclusions: Dolutegravir achieved target PK exposures in adolescents. Dolutegravir was safe and well tolerated, providing good virologic efficacy through week 48.

Insulin-like growth factor-1 and lean body mass in HIV-infected children.

Objectives:To describe insulin-like growth factor-1 (IGF-1) and insulin-like growth factor-1-binding protein-1 (IGFBP-1) and IGFBP-3 in HIV+ children before and after initiating or changing antiretroviral therapy and to evaluate association of growth and body composition to growth factors at baseline and over time. Methods:Ninety-seven prepubertal HIV+ children aged 1 month to younger than 13 years were observed over 48 weeks after beginning or changing antiretroviral therapy. Serum IGF-1, IGFBP-1, and IGFBP-3 were measured and compared with age- and sex-specific norms. Anthropometric measures were compared as follows: subjects vs matched children from (a) the National Health and Nutrition Examination Survey to generate z scores and (b) HIV-exposed, uninfected children from Women and Infants Transmission Study; and subjects with normal vs abnormal IGF-1 and IGFBP concentrations at baseline. Anthropometric changes were compared for children whose IGF-1 level normalized vs remaining subjects. Multivariate analysis adjusting for sex, race, and baseline age evaluated associations between anthropometry and IGF-1 and IGFBP concentrations. Results:In multivariate analysis, lower baseline IGF-1 and IGFBP-3 were associated with lower mean weight, height, mid-arm muscle circumference, and mid-thigh circumference z scores. Twenty-four percent of children had a low IGF-1 level at baseline, 50% of whom normalized IGF-1 on study. Children whose IGF-1 normalized had greater increases in mean mid-arm muscle circumference z score (1.00 vs −0.03, P = 0.029), but a trend toward lesser mean height increase (P = 0.082) than remaining subjects. Likewise, in comparison to controls from Women and Infants Transmission Study, mean mid-arm muscle circumference also increased more in children whose IGF-1 normalized (P = 0.024) but mean height changed less (P = 0.003). Fifty-five percent of children had elevated IGFBP-1 at baseline, 69% of whom normalized. Conclusions:IGF-1 increases and IGFBP-1 decreases in HIV-infected children upon initiation or change in antiretroviral therapy. Improved muscle mass, but not linear growth, is associated with normalized IGF-1 concentration. These findings suggest that IGF-1 may merit evaluation as a potential therapeutic strategy to improve lean body mass in HIV-infected children.