Sopheak Ngin

Dependence of Efavirenz- and Rifampicin-Isoniazid–Based Antituberculosis Treatment Drug-Drug Interaction on CYP2B6 and NAT2 Genetic Polymorphisms: ANRS 12154 Study in Cambodia

We investigated the population pharmacokinetics and pharmacogenetics of efavirenz in 307 patients coinfected with human immunodeficiency virus and tuberculosis and included in the Cambodian Early vs Late Initiation of Antiretrovirals trial (CAMELIA) in Cambodia. Efavirenz (600 mg/d) and stavudine plus lamivudine were administered in addition to standard antituberculosis treatment, including rifampicin and isoniazid. Blood samples were obtained a mean of 14 hours after efavirenz intake at weeks 2 and 6 after initiation of efavirenz and weeks 22 (efavirenz plus antituberculosis drugs) and 50 (efavirenz alone) after initiation of antituberculosis treatment. Ten patients participated in an extensive pharmacokinetic study after week 50. CYP2B6 G516T and C485-18T polymorphisms were the most significant covariates, with weight showing a significant minor effect. Change in efavirenz apparent clearance in patients taking both efavirenz and antituberculosis treatment was highly dependent on NAT2 polymorphism, as a possible surrogate of isoniazid exposure. Patients carrying the CYP2B6 516 TT genotype and slow-acetylation NAT2 phenotype had the lowest efavirenz apparent clearance. These data suggest that the inducing effect of rifampicin is counterbalanced by a concentration-dependant inhibitory effect of isoniazid on efavirenz clearance.

High survival and treatment success sustained after two and three years of first-line ART for children in Cambodia

BackgroundLong-term outcomes of antiretroviral therapy (ART) in children remain poorly documented in resource-limited settings. The objective of this study was to assess two-and three-year survival, CD4 evolution and virological response among children on ART in a programmatic setting in Cambodia.MethodsChildren treated with first-line ART for at least 24 months were assessed with viral load testing and genotyping. We used Kaplan-Meier analysis for survival and Cox regression to identify risk factors associated with treatment failure.ResultsOf 1168 registered HIV-positive children, 670 (57%) started ART between January 2003 and December 2007. Survival probability was 0.93 (95% CI: 0.91-0.95) and 0.91 (95% CI: 0.88-0.93) at 24 and 36 months after ART initiation, respectively. Median CD4 gain for children aged over five years was 704 cells/mm3 at 24 months and 737 at 36 months. Median CD4 percentage gain for children under five years old was 15.2% at 24 months and 15% at 36 months. One hundred and thirty children completed at least 24 months of ART, and 138 completed 36 months: 128 out of 268 (48%) were female. Median age at ART initiation was six years.Overall, 22 children had viral loads of >1000 copies/ml (success ratio = 86% on intention-to-treat-analysis) and 21 of 21 presented mutations conferring resistance mostly to lamivudine and non-nucleoside reverse transcriptase inhibitors. Risk factors for failure after 24 and 36 months were CD4 counts below the threshold for severe immunosupression at those months respectively. Only two out of 22 children with viral loads of >1000 copies/ml met the World Health Organization immunological criteria for failure (sensitivity = 0.1).ConclusionsGood survival, immunological restoration and viral suppression can be sustained after two to three years of ART among children in resource-constrained settings. Increased access to routine virological measurements is needed for timely diagnosis of treatment failure.

High efficacy of lopinavir/r-based second-line antiretroviral treatment after 24 months of follow up at ESTHER/Calmette Hospital in Phnom Penh, Cambodia

BackgroundThe number of patients on second-line highly active antiretroviral therapy (HAART) regimens is increasing in resource-limited settings. We describe the outcomes after 24 months for patients on LPV/r-based second-line regimens followed up by the ESTHER programme in Phnom Penh, Cambodia.MethodsSeventy patients who initiated second-line HAART regimens more than 24 months earlier were included, and immuno-virological data analyzed. HIV RNA viral load was determined by real-time RT-PCR. HIV-1 drug resistance was interpreted according to the ANRS algorithm.ResultsOf the 70 patients, two were lost to follow up, three died and 65 (92.8%) remained on second-line treatment after 24 months of follow up (median duration of treatment: 27.4 months). At switch to second-line, the median CD4 T cell count was 106 cells/mm3 and the median viral load was 4.7 Log10. Second-line regimens prescribed were ddI/3TC/LPV/r (65.7%), ddI/TDF/LPV/r (10.0%), ddI/AZT/LPV/r (8.6%) and TDF/3TC/LPV/r (7.1%). The median CD4 T cell gain was +258 cells/mm3 at 24 months (n = 63). After 24 months of follow up, 92.3% (60/65) of the patients presented undetectable viral loads, giving an overall treatment success rate of 85.7% (CI: 75.6- 92.0) in intent-to-treat analysis.ConclusionsThese data suggest that a LPV/r-based second-line regimen is associated with a high rate of virological suppression and immune reconstitution after 24 months of follow up in Cambodia.

Low Prevalence of Drug Resistance Transmitted Virus in HIV Type 1-Infected ARV-Naive Patients in Cambodia

Abstract Between November 2006 and June 2007, HIV-1 reverse transcriptase (RT) and protease (PR) genes of 67 ARV-naive Cambodian patients were amplified and sequenced. At inclusion, the median age and duration of HIV infection were 28 and 1.1 years, respectively. The median CD4 and HIV-1 RNA were 611 cells/ml [IQR: 525-759] and 4.0 log(10) copies/ml [IQR: 3.4-4.6]. Among 67 HIV-1 strains, 95.5% were CRF 01_AE viruses (n = 64) whereas three clustered with subtype B. RT analysis indicated that only 1 patient out of 67, presenting K103N and M184V mutations, was resistant to NVP/EFV and 3TC/FTC. No primary resistance to protease inhibitors was detected in 59 amplified protease genes. The 1.49% (IC 95%: 0.04-8.04%) prevalence of transmitted drug-resistant strains in drug-naive patients was low in our study. Surveys of drug-resistant transmitted viruses should be regularly performed regarding the increasing access to HAART in Cambodia.

Nonhuman primate retroviruses from Cambodia: High simian foamy virus prevalence, identification of divergent STLV-1 strains and no evidence of SIV infection

Nonhuman primates (NHPs) carry retroviruses such as simian immunodeficiency viruses (SIV), simian T-cell lymphotropic viruses (STLV) and simian foamy viruses (SFV). Here, we revisited NHPs from Cambodia to assess the prevalence and diversity of these retroviruses using updated viral detection tools. We screened blood from 118 NHPs consisting of six species (Macaca fascicularis (n=91), Macaca leonine (n=8), Presbytis cristata (n=3), Nycticebus coucang (n=1), Hylobates pileatus (n=14), and Pongo pygmaeus) (n=1) by using a Luminex-based multiplex serology assay that allows the detection of all known SIV/HIV and SFV lineages. We also used highly sensitive PCR assays to detect each simian retrovirus group. Positive PCR products were sequenced and phylogenetically analyzed to infer evolutionary histories. Fifty-three of 118 (44.9%) NHPs tested positive for SFV by serology and 8/52 (15.4%), all from M. fascicularis, were PCR-confirmed. The 8 novel SFV sequences formed a highly supported distinct lineage within a clade composed of other macaque SFV. We observed no serological or molecular evidence of SIV infection among the 118 NHP samples tested. Four of 118 (3.3%) NHPs were PCR-positive for STLV, including one M. fascicularis, one P. cristata, and two H. pileatus. Phylogenetic analyses revealed that the four novel STLV belonged to the PTLV-1 lineage, outside the African radiation of PTLV-1, like all Asian PTLV identified so far. Sequence analysis of the whole STLV-1 genome from a H. pileatus (C578_Hp) revealed a genetic structure characteristic of PTLV. Similarity analysis comparing the STLV-1 (C578_Hp) sequence with prototype PTLVs showed that C578_Hp is closer to PTLV-1s than to all other types across the entire genome. In conclusion, we showed a high frequency of SFV infection but found no evidence of SIV infection in NHPs from Cambodia. We identified for the first time STLV-1 in a P. cristata and in two H. pileatus.

HIV-1 Protease Inhibitors Resistance Profiles in Patients with Virological Failure on LPV/r-based 2nd Line Regimen in Cambodia

Objective: To describe the ARV resistance profiles of patients experiencing virological failure after at least 6 months on LPV/r-based 2nd line regimen in Cambodia. Design: Retrospective analysis of resistance testing of 89 patients with detectable viral load under LPV/r-based 2nd line regimen. Methods: Bulk sequencing of HIV-1 protease, reverse transcriptase and integrase PCR products. Results: Protease gene amplification was successful for 71/89 patients (80%). All were infected by CRF01_AE viruses. Among them, 42 did not present any resistance to PIs. A high level of resistance to PIs was observed for the 29 remaining patients. Twenty-six were resistant to LPV/r (8 possibly resistant). Twenty-eight, 21 and 20 were also found resistant to IDV, ATV/r and FPV/r, respectively. Twenty-six were resistant to NFV (11 possibly) and 22 to SQV/r (9 possibly). Finally, 22/29 (75.8%) were resistant to at least 3 PIs. Interestingly, 78.6% (22/29) were found sensitive to DRV/r. In this group, a high frequency of resistance to RTIs including ETV was also reported. No resistance to raltegravir (RAL) or elvitegravir (EVG) was observed (n=24). Detailed ARV histories documented for 15 patients revealed past exposition to multiple RTIs and PIs. Conclusion: Almost 2/3 of patients (60/89) with virological failure on LPV/r-based 2nd line in our study were not in urgent need for treatment change. In contrast, switching treatment was clearly required for 1/3 (29/89) presenting high level of resistance to PIs and RTIs. For those patients, DRV, RAL/EVG, and potentially ETV, could be good candidates for 3rd line ARV regimen if available.

Lopinavir/ritonavir-based second line antiretroviral treatment in children at National Pediatric Hospital, Phnom Penh, Cambodia

Background Cambodia has scaling up a large national ART program using 1st line therapy (d4T or AZT+3TC+NVP or EFV). According to NCHADS, as December 31st 2008, 3,067 children were on HAART in Cambodia, 746 of them were followed-up in Child Health Improvement Clinic (CHIC) at the National Pediatric Hospital, (NPH), with French Red Cross technical support. Fifthy-three out of 746 already switched on LPVr-based 2nd line regimen.

HIV drug resistance profile of HIV-1 CRF 01_AE protease and integrase coding regions in HIV infected Cambodian patients failing LPV-based 2nd line antiretroviral regimen.

Background By the end of 2009, the number of HIV-1 infected patients on RTI-based 1 line and PI-based 2 line ARV regimen in Cambodia reached 34,000 and 1,500, respectively. We already reported good virological and immunological responses after 1 to 4 years in cohorts of patients on 1 line and more recently, among an Esther cohort of 70 patients after 2 years on LPVr-based 2 line regimen. However, emergence of LPV resistant associated mutations is becoming a major concern in low and middle income countries.

Very early diagnosis of HIV infection in newborn at day 0–day 3 on DBS in Cambodia

Methods Very early diagnosis was explained and proposed, before and/or after delivery, to HIV positive mothers delivering at Calmette and hospitals and health centers supported by Magna Children at Risk (NMCHC, Chey Chumneas Hospital and 3 Municipality Health Centers). A first negative HIV-DNA negative DBS at day 0–day 3 was followed up by a second DBS at W6. HIV-DNA positive DBS at d0–d3, or at week 6 were followed up by a venipuncture as soon as possible for HIV-RNA quantification (Kit G2 ANRS) and CD4 count. Preliminary results Heel prick blood specimens were spotted on DBS for 272 newborns (ratio M/F = 1.3) at d0–d3. HIV DNA was detected in 3 of 272 babies (rIUT rate: 1.1%). One of them died before week 6. The two others presenting detectable HIV-1 RNA viral loads at week 6 (6.4 and 6.9 log10 copies/ ml with CD4 at 19% and 21%, respectively) started first line ARV regimen and became HIV-1 RNA undetectable after 10 and 4 months of treatment. Among the 269 HIVDNA negative newborn at d0–d3, 228 (84.5%) have been already seen at week 6 for virological confirmation, 23 are still waiting for the visit of the week 6, 14 were lost of follow up and 4 died without any AIDS clinical symptoms. 226 of 228 DBS were confirmed HIV-DNA negative at week 6 whereas 2 infants became HIV-DNA positive (PPT rate: 0.8%). Both were confirmed HIV-RNA positive two weeks later (5.8 and 6.2 log10 copies/ml with CD4 at 33% and 26%, respectively) and will soon begin their ARV treatment.

Effectiveness of a district-wide programme for the prevention of mother-to-child transmission of HIV in Cambodia. Experience from six maternity units in Phnom Penh and Kandal

Background Despite the great advances in developing and implementing effective interventions to prevent HIV transmission from infected mothers to their infants, almost 2,000 infants are infected every day through MTCT in resourcepoor countries. In these settings, where prevention of mother to child transmission of HIV-1 (PMTCT) programs are in place, the uptake and effectiveness of the PMTCT comprehensive program need to be regularly monitored.