Presentation on theme: "Emerging patterns of drug resistance and viral tropism in cART-naïve and failing patients infected with HIV-1 subtype C Thumbi Ndung’u, BVM, PhD Associate."— Presentation transcript:
1 Emerging patterns of drug resistance and viral tropism in cART-naïve and failing patients infected with HIV-1 subtype CThumbi Ndung’u, BVM, PhDAssociate ProfessorDirector, HIV Pathogenesis ProgrammeDoris Duke Medical Research InstituteNelson R. Mandela School of MedicineUniversity of KwaZulu-Natal
6 >25 years of HIV/AIDS > 33 For every 2 people put on treatment, 5 others are infected
7 Selection of Resistant strains Selection of resistant quasispecies Treatment beginsDrug-susceptible quasispeciesDrug-resistant quasispeciesSelection of resistant quasispeciesViral loadIncomplete suppressionInadequate potencyInadequate drug levelsInadequate adherencePre-existing resistanceTime
8 Study rationale Background: Relatively limited information on coreceptor usage by HIV-1 subtype C isolates, particularly in children. However, most studies suggest very rare CXCR4 usageSome reports suggest increasing X4 usage (in adults) eg. Johnston et. al. (n=28), 50% using X4 among ART experienced viremic patientsPreviously used methods may be biased because they involved first generating viral isolates by co-culture
9 Study rationaleART may boost T-cell immune responses which have been shown to preferentially suppress X4 viruses. Thus partially effective therapy may select against X4 viruses (Deeks et al, JID 2004; Harouse et al, PNAS 2003)ART reduces CCR5 expression on T cells (due to reduction in T cell activation) potentially selecting for X4 viruses (Brumme et al, JID 2005; Anderson et al, AIDS 1998)Suboptimal drug metabolism (such as AZT) in the cellular reservoirs for X4 viruses has been suggested and could lead to selection for X4 viruses (Boucher et al, AIDS 1992)
10 AimsSpecific Aims:1) To determine the prevalence of major drug mutations in ART-naïve and failing children and adults2) Determine overall prevalence of X4 tropism among children and adults initiating and failing HAART3) Compare prevalence of X4-utilizing viruses between ART-naïve and ART-experienced subjects with detectable viremia4) Explore factors associated with viral tropism in HIV-1C infection
11 HIV-1 Genotyping Assay plasma Blood cells T T C T C G A T C G RNA centrifugationBlood cellsRNART-PCRcDNAPCRDNAPCRDye terminatorsA T G CTTCTCGATCGSoftware analysisATAGACCAG : consensus sequenceI Q QATCGACCTG : patient sequenceI Q *L
12 + Trofile assay summary- for coreceptor usage pcDNA-env gag pol env 5’LTRgagpolenvvifvprvputatrevLuc3’LTR+pcDNA-envCMVpAEnvLuciferase assay0.2µfilter0.2µfilter293T cellsCCR5 cellsCXCR4 cells
13 Table 1: Children Demographic and Clinical Characteristics NOTE. Data are no. (%) of children unless otherwise indicated. For cases where the data is incomplete, the n value is indicated.Statistical tests: a Mann-Whitney U test and b Fisher’s exact test (for WHO stage analysis, stages I, II and III were grouped together).
14 Table 1: Patient Demographic and Clinical Characteristics Cont. NOTE. Data are no. (%) of children unless otherwise indicated. For cases where the data is incomplete, the n value is indicated.Prior treatment indicated with underlined drug/s changed ● d4T, 3TC, ritonavir (n=1); * unknown; ○ d4T, 3TC, EFV (n=1) and AZT, 3TC, NVP (n=1); d4T, 3TC, kaletra; d4T, 3TC, EFV.Statistical tests: a Mann-Whitney U test and b Fisher’s exact test
15 Frequency of drug resistance mutations and levels of resistance in HAART-failing children to the NRTIs (a) and NNRTIs (b)58.5% had TAMs39% had ≥3 TAMs
16 Average no. of major mutation in patients failing standard first line treatment (n=30) d4T/3TC/EFV (n=25)3 patients have no DRMs (VLs are 617; 79,400; 228,000)20 NRTI DRM2 NNRTI DRM(one patient had a PI DRM)d4T/3TC/kaletra (n=5)3 patients have no DRMs (VLs are 143,000; 198,000; 4,410,000)1 patient has 1 NRTI DRM (M184V) only1 patient has 1 NRTI (M184V) and 1 NNRTI DRM (Y181C)
17 d4T/3TC/EFV (n=25) → AZT/ddI/Kaletra Potential low-level (n=2) How many major mutations compromise the standard second line treatment?d4T/3TC/EFV (n=25) → AZT/ddI/Kaletra3 patients susceptible to all drugs – no change neededAll patients susceptible to kaletra3 patients susceptible to 3 drugs in standard second line tx.AZT ResistanceddI ResistanceSusceptible (n=2)High-Level (n=2)Low level (n=5)Potential low-level (n=2)Low-level (n=1)Intermediate (n=2)Intermediate (n=8)Low-level (n=3)High-level (n=1)High-Level (n=4)
18 Overall, 13 of 25 (52%) patients will have some degree of resistance (low to high) to two of the three drugs in their new regimen (excluding potential low-level resistance)
19 d4T/3TC/kaletra (n=5) → AZT/ddI/(NVP/EFV) 4 of 5 patients are susceptible to all second line drugs1 patient had intermediate resistance to EFV (3.7 yrs old)(Y181C)Note: Overall better if not changedAll still susceptible to PIs and d4T with 3 patients still susceptible to 3TC [ high-level resistance to 3TC (M184V)]Patients <3 years will be put on NVPPatients >3 years will be put on EFV
20 Comparison of coreceptor usage in HAART-failing and HAART-naïve children
23 Evaluation of Several Genotypic Tools for the Prediction of CXCR4-usage a A total of 52 pure subtype C isolates with both phenotypic and genotypic data were included in this analysis. bA false positive rate of 10% was used. c A combination of the first four genotypic tools were used where the majority prediction was considered as the final genotype prediction (n=47).
26 What is the outcome of patients failing if started on the standard second line of treatment without having genotypic data?
27 Average no. of major mutation in patients failing standard first line treatment (n=16) d4T/3TC/ (EFV/NVP) (n=16) (Note: 2 on NVP)No major PI mutations1.75 NRTI DRM1.69 NNRTI DRM
28 How many compromise the standard second line treatment? d4T/3TC/ (EFV/NVP) (n=16) → AZT/ddI/LPV/rAll patients susceptible to kaletra (LPV/r)6 patients susceptible to all 3 drugs in standard second line tx.AZT ResistanceddI ResistanceSusceptible (n=4)Potential low-level (n=3)High-Level (n=1)Potential low-level (n=2)Susceptible(n=1)Low-level (n=1)Low-level (n=2)Intermediate (n=2)
29 4 of 16 (25%) patients will have some degree of resistance (low to intermediate) to two of the three drugs in their new regimen (excluding potential low-level resistance).6 of 16 (37.5%) will have some degree of resistance (low to high) to one of the three drugs in their new regimen (excluding potential low-level resistance).
30 High levels of CXCR4 viruses in patients failing therapy- limited salvage options
31 V3 loop-based methods for coreceptor usage prediction % of sequences correctly predicted% of R5 sequences correctly predicted% of X4/D/M sequences correctly predicted11/25789055Overall net V3 charge757181C-PSSM8572Geno2Pheno848682Combined algorithm*8780*In the combined algorithm, concordant results from at least 3 of 4 methods(i.e. the amino acids at positions 11 and/or 25, the overall net V3 charge, C-PSSMprediction and Geno2Pheno prediction) were used.
32 Conclusions Virologic failure is mainly due to DRMs High levels of TAMs is source of concern- suggests subpotimal adherence and need for intensive monitoringHigher levels of CXCR4 using viruses among HAART experienced patients- need to explore CCR5 antagonists as part of first-line/early treatmentCollectively, these data highlight the need for intensified adherence counselling and better HAART monitoring to maximize benefits.