Laura Smeaton

Pharmacogenetics of Long-Term Responses to Antiretroviral Regimens Containing Efavirenz and/or Nelfinavir: An Adult AIDS Clinical Trials Group Study

BACKGROUND Efavirenz and nelfinavir are metabolized by cytochrome P-450 (CYP) 2B6 and CYP2C19, respectively, with some involvement by CYP3A. Nelfinavir is a substrate for P-glycoprotein, which is encoded by MDR1. The present study examined associations between genetic variants and long-term responses to treatment. METHODS Adult AIDS Clinical Trials Group study 384 randomized antiretroviral-naive subjects to receive efavirenz and/or nelfinavir plus 2 nucleoside analogues, with follow-up lasting up to 3 years. Population pharmacokinetics were estimated from a nonlinear mixed-effects model. Polymorphisms in CYP2B6, CYP2C19, CYP3A4, CYP3A5, and MDR1 were characterized. RESULTS The 504 participants in the genetic study included 340 efavirenz recipients and 348 nelfinavir recipients (184 of the 504 participants received both efavirenz and nelfinavir). Of the participants, 49% were white, 31% were black, and 19% were Hispanic. Plasma exposure to efavirenz and nelfinavir in each population was significantly associated with the polymorphisms CYP2B6 516G-->T and CYP2C19 681G-->A, respectively. Among efavirenz recipients, the MDR1 position 3435 TT genotype was associated with decreased likelihood of virologic failure and decreased emergence of efavirenz-resistant virus but not with plasma efavirenz exposure. Among nelfinavir recipients, a trend toward decreased virologic failure was associated with the polymorphism CYP2C19 681G-->A. CONCLUSIONS Genetic variants predict plasma exposure to efavirenz and nelfinavir, and they may predict virologic failure and/or emergence of drug-resistant virus. These associations with treatment responses must be validated in other studies.

Use of Changes in Plasma Levels of Human Immunodeficiency Virus Type 1 RNA to Assess the Clinical Benefit of Antiretroviral Therapy

Data from 1330 human immunodeficiency virus type 1 (HIV-1)-infected patients enrolled in seven antiretroviral treatment trials were analyzed to characterize the clinical benefit of treatment-mediated reductions in plasma HIV-1 RNA levels. The risk of a new AIDS-defining event or death was reduced proportionally to the magnitude of the reduction of the HIV-1 RNA level during the first 6 months of therapy. Pretherapy HIV-1 RNA levels were prognostic independently of on-therapy levels. In addition, the reduction in risk associated with any given reduction of the level of HIV-1 RNA did not vary by pretherapy level. Having either a reduction in HIV-1 RNA level or an increase in CD4+ lymphocyte count, or both, was associated with a delay in clinical disease progression. This indicates that patient prognosis should be assessed using both HIV-1 RNA and CD4+ lymphocyte responses to therapy.

Infant Morbidity, Mortality, and Breast Milk Immunologic Profiles among Breast-Feeding HIV-Infected and HIV-Uninfected Women in Botswana

BACKGROUND Infants of human immunodeficiency virus (HIV)-infected women have high mortality, but the immunologic integrity and protection afforded by the breast milk of HIV-infected women is unknown. METHODS We determined morbidity and mortality by 24 months among breast-fed infants of 588 HIV-infected and 137 HIV-uninfected women followed-up in a clinical trial in Botswana. A matched case-control study compared clinical, behavioral, and breast milk immunologic parameters among 120 HIV-infected women by infant outcome. Breast milk factors were also compared between HIV-infected and HIV-uninfected women. RESULTS Twenty-four-month mortality was 29.5% among HIV-infected infants, 6.7% among HIV-exposed uninfected infants, and 1.6% among HIV-unexposed infants. No differences were detected in breast milk immunologic profiles of HIV-infected women whose infants were either ill or well. Discontinuation of breast-feeding was the strongest predictor of illness (P<.001). Levels in breast milk of pathogen-specific immunoglobulin (Ig) G and IgA to Haemophilus influenzae, Campylobacter jejuni, Helicobacter pylori, Streptococcus pneumoniae, and innate immune factors were not lower among HIV-infected women than among HIV-uninfected women. CONCLUSIONS Mortality was higher among HIV-infected and HIV-exposed infants than among HIV-unexposed infants. However, the immunologic profiles of breast milk among HIV-infected women were intact, and discontinuation of breast-feeding was the primary risk for infant morbidity. Thus, the breast milk of HIV-infected women may confer protection against common infant pathogens. TRIAL REGISTRATION (ClinicalTrials.Gov) identifiers: NCT00197691 and NCT00197652.

Highly Active Antiretroviral Therapy Started during Pregnancy or Postpartum Suppresses HIV-1 RNA, but Not DNA, in Breast Milk

BACKGROUND The ability of highly active antiretroviral therapy (HAART) to reduce human immunodeficiency virus type 1 (HIV-1) RNA and DNA in breast milk has not been described. METHODS We compared breast-milk HIV-1 RNA and DNA loads of women in Botswana who received HAART (nevirapine, lamivudine, and zidovudine) and women who did not receive HAART. RESULTS Women in the HAART group received treatment for a median of 98 days (range, 67-222 days) at the time of breast-milk sampling; 23 (88%) of 26 had whole breast-milk HIV-1 RNA loads <50 copies/mL, compared with 9 (36%) of 25 women who did not receive HAART (P=.0001). This finding remained significant in a multivariate logistic-regression model (P = .0006). The whole-milk HIV-1 DNA load was unaffected by HAART. Of women who received HAART, 13 (50%) of 26 had HIV-1 DNA loads <10 copies/10(6) cells, compared with 15 (65%) of 23 who did not receive HAART (P = .39). CONCLUSIONS HAART suppressed cell-free HIV-1 RNA in breast milk and may therefore reduce mother-to-child transmission (MTCT) of HIV-1 via breast-feeding. However, HAART initiated during pregnancy or early after delivery had no apparent effect on cell-associated HIV-1 DNA loads in breast milk. Clinical trials to determine MTCT among breast-feeding women receiving HAART are needed.

In vivo antagonism with zidovudine plus stavudine combination therapy.

Human immunodeficiency virus (HIV)-infected subjects receiving zidovudine were randomized either to add stavudine (d4T) or didanosine (ddI) to their current regimen or to switch to ddI or d4T monotherapy. After 16 weeks of therapy, the mean reduction in HIV RNA from baseline was 0.14 log(10) copies/mL in patients receiving d4T or zidovudine plus d4T. In subjects receiving ddI or ddI plus zidovudine, reductions were 0.39 and 0.56 log(10), respectively. CD4 cell counts remained stable or showed modest increases in all arms except the zidovudine plus d4T arm. Patients receiving zidovudine plus d4T showed progressive declines in CD4 cell counts with a median of 22 cells/mm(3) below baseline by 16 weeks. Examination of intracellular levels of d4T-triphosphate in 6 subjects was consistent with previous in vitro studies demonstrating pharmacologic antagonism between zidovudine and d4T. Analysis of these data suggests that zidovudine and d4T should not be prescribed in combination and that ddI provides greater antiviral activity than d4T in zidovudine-treated patients.

Treatment with Amprenavir Alone or Amprenavir with Zidovudine and Lamivudine in Adults with Human Immunodeficiency Virus Infection

Amprenavir is a human immunodeficiency virus (HIV) protease inhibitor with a favorable pharmacokinetic profile and good in vitro activity. Ninety-two lamivudine- and protease inhibitor-naive individuals with >/=50 CD4 cells/mm3 and >/=5000 HIV RNA copies/mL were assigned amprenavir (1200 mg) alone or with zidovudine (300 mg) plus lamivudine (150 mg), all given every 12 h. After a median follow-up of 88 days, the findings of a planned interim review resulted in termination of the amprenavir monotherapy arm. Among 85 subjects with confirmed plasma HIV RNA determination, 15 of 42 monotherapy versus 1 of 43 triple-therapy subjects had an HIV RNA increase above baseline or 1 log10 above nadir (P=.0001). For subjects taking triple therapy at 24 weeks, the median decrease in HIV RNA was 2.04 log10 copies/mL, and 17 (63%) of 27 evaluable subjects had <500 HIV RNA copies/mL. Treatment with amprenavir, zidovudine, and lamivudine together reduced the levels of HIV RNA significantly more than did amprenavir monotherapy.

Detection of Hepatitis C Virus (HCV) in Serum and Peripheral-Blood Mononuclear Cells from HCV-Monoinfected and HIV/HCV–Coinfected Persons

It has been speculated that hepatitis C virus (HCV) replicates in peripheral-blood mononuclear cells (PBMCs), which, therefore, may be a site for interaction with human immunodeficiency virus (HIV). We used strand-specific real-time polymerase chain reaction to detect HCV RNA in 28 HCV-monoinfected and 20 HIV/HCV-coinfected women. At the first visit, positive-strand HCV RNA was detected in serum samples from 89% of the women, whereas positive-strand HCV RNA was detected in PBMC samples from 32% and 55% of the HCV-monoinfected and HIV/HCV-coinfected women, respectively. After initiation of antiretroviral therapy, the HIV/HCV-coinfected women were significantly more likely to have detectable positive- and negative-strand HCV RNA in the PBMC compartment than were the HCV-monoinfected women. HIV and HCV RNA levels were not correlated. Serum HCV RNA levels were correlated over time; HCV RNA levels in the serum and PBMC compartments were not. These data suggest differential regulation of HCV RNA in the serum and PBMC compartments and may partially explain the limited HCV antiviral response rates observed in coinfected persons.

The Effects of Protease Inhibitor Therapy on Human Immunodeficiency Virus Type 1 Levels in Semen (AIDS Clinical Trials Group Protocol 850)

Antiretroviral therapy may lead to decreased shedding of human immunodeficiency virus type 1 (HIV-1) in genital secretions. Thirty men, 19 receiving amprenavir and 11 receiving amprenavir, zidovudine, and lamivudine, donated blood and semen while undergoing treatment, to evaluate the effects of these medications on HIV-1 shedding in semen. Before therapy, 4 men had HIV-1 RNA levels in seminal plasma >6.0 log10 (1 million) copies/mL, markedly higher than levels in blood plasma. Most men (77%) had HIV-1 RNA levels in seminal plasma below the limit of quantification during therapy. Amprenavir alone suppressed HIV-1 RNA levels to <400 copies/mL in seminal plasma in the majority of patients, the first direct demonstration of the antiretroviral effects of a protease inhibitor in the male genital tract. However, 8 men (27%) had measurable HIV-1 in seminal plasma at their last study visit, 4 with increasing levels. Persistent replication of HIV in the genital tract may have implications for the selection of resistant virus and sexual transmission of HIV-1.

Compartmentalization of Hepatitis C Virus (HCV) during HCV/HIV Coinfection

Extrahepatic replication has important implications for the transmission and treatment of hepatitis C virus (HCV). We analyzed longitudinal HCV diversity in peripheral-blood mononuclear cells (PBMCs) and serum during HCV monoinfection and HCV/HIV coinfection to determine whether distinct amino acid signatures characterized HCV replicating within PBMCs. Analysis of E1-HVR1 sequences demonstrated higher serum genetic distances among HCV/human immunodeficiency virus (HIV)-coinfected persons. Moreover, consensus PBMC sequences were rarely identical to those in the corresponding serum, suggesting divergence in these 2 compartments. Three of 5 HCV/HIV-coinfected participants showed evidence of HCV compartmentalization in PBMCs. Additionally, signature sequence analysis identified PBMC-specific amino acids in all HCV/HIV-coinfected persons. To our knowledge, this is the first study to identify specific amino acids that may distinguish HCV variants replicating in PBMCs. It is provocative to speculate that extrahepatic HCV diversity may be an important determinant of treatment response and thus warrants additional study, particularly during HCV/HIV coinfection.

Characterization of HIV-HBV coinfection in a multinational HIV-infected cohort.

Objective:To understand the HIV–hepatitis B virus (HBV) epidemic from a global perspective by clinically and virologically characterizing these viruses at the time of antiretroviral therapy (ART) initiation in a multinational cohort. Methods and design:HIV-infected patients enrolled in two international studies were classified as HIV–HBV coinfected or HIV monoinfected prior to ART. HIV–HBV coinfected patients were tested for HBV characteristics, hepatitis D virus (HDV), a novel noninvasive marker of liver disease, and drug-resistant HBV. Comparisons between discrete covariates used &khgr;2 or Fishers exact tests (and Jonchkheere–Terpstra for trend tests), whereas continuous covariates were compared using Wilcoxon Rank-Sum Test. Results:Of the 2105 HIV-infected patients from 11 countries, the median age was 34 years and 63% were black. The 115 HIV–HBV coinfected patients had significantly higher alanine aminotransferase and aspartate aminotransferase values, lower BMI, and lower CD4+ T-cell counts than HIV monoinfected patients (median 159 and 137 cells/&mgr;l, respectively, P = 0.04). In the coinfected patients, 49.6% had HBeAg-negative HBV, 60.2% had genotype A HBV, and 13% were HDV positive. Of the HBeAg-negative patients, 66% had HBV DNA 2000 IU/ml or less compared to 5.2% of the HBeAg-positive individuals. Drug-resistant HBV was not detected. Conclusion:Screening for HBV in HIV-infected patients in resource-limited settings is important because it is associated with lower CD4+ T-cell counts. In settings in which HBV DNA is not available, HBeAg may be useful to assess the need for HBV treatment. Screening for drug-resistant HBV is not needed prior to starting ART in settings in which this study was conducted.