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ARV Drug Resistance

ARV Drug Resistance. Dr Pontiano Kaleebu Pontiano Kaleebu MBchB PhD MRC/UVRI Uganda Research Unit on AIDS. Summary of presentation. Mechanisms of ARV resistance How do we look for resistance Clinical implications Some review of resistance in Uganda (Including Dart)

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ARV Drug Resistance

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  1. ARV Drug Resistance Dr Pontiano Kaleebu Pontiano Kaleebu MBchB PhD MRC/UVRI Uganda Research Unit on AIDS

  2. Summary of presentation • Mechanisms of ARV resistance • How do we look for resistance • Clinical implications • Some review of resistance in Uganda (Including Dart) • National HIVDR Drug Resistance Prevention, Monitoring and Surveillance Plan

  3. Mechanisms of Drug Resistance and Diversity • HIV-1 genetic variability is generated by the lack of proof-reading ability of reverse transcription • Rapid turnover of HIV in vivo • Host selective immune pressures • Recombination events during replication • Of the 10 billion new viruses produced, 1/1000 (10 million) viruses per day will have one new "error" (mutation) some of which make the virus resistant to ART drugs

  4. Selective Pressures of Therapy Copies/mL Treatment begins (CD4 <200 cells/mm3) 900,000 Drug-susceptible quasispecies Drug-resistant quasispecies Selection of resistant quasispecies 100,000 • Incomplete suppression • Inadequate potency • Inadequate drug levels • Inadequate adherence • Pre-existing resistance Viral load V. Failure < 400 Time

  5. Other factors • Genetic barrier: • Some drugs like lamivudine and NNRTIs have a low genetic barrier in that they only require a single mutation to cause resistance. • On the other hand drugs like abacavir and indinavir require at least three mutations before significant loss of activity • Half life: • Long half life e.g Tenofovir

  6. Patterns of mutation • Degree of resistance by a mutation differs • E.g M184V mutation: • <5 fold resistance to abacavir and didanosine >1000 fold resistance to lamuvidine • K103R leads to 20-30 fold resistance to NNRTI • Cross-resistance; 151M arises primarily with DDI but leads to resistance to most NRTIs

  7. Patterns of mutation • K65R causes tenofovir resistance but increases sensitivity to AZT • NVP Y181C can suppress effect of AZT 215 mutation • Mutation patterns observed in combination treatment have become complex and interpretation needs experience

  8. Measurement of HIV Drug Resistance • Genotypic assays: Commercial e.g ViroSeq Kit (Abbot Diagonostics), TrueGene Kit; In house • Phenotypic assays: Virco Laboratories (Belgium, USA) • “Virtual” phenotype • Use of genotype results to predict phenotypic susceptibility based originally on database of paired genotype and phenotype data or, more recently, through scores derived from linear regression analysis

  9. Genotyping assays

  10. Acquire consensus sequences And save them as text files Cross-check for contamination from older samples by phylogenetic analysis

  11. Phenotypic assays • “Culture and sensitivity” • In vitro determination of drug susceptibility: compare the concentration at which virus replication is inhibited by 50% (IC50) compare with a reference strain • Cost: about US $300

  12. ZDV/3TC/ABC: Example of Slow Stepwise Appearance of Mutations in Subjects With Virologic Failure M184V D67N/D, K70R/K, M184V M184V, T215T/Y M41L/M, M184V, T215Y M41L, M184V, T215Y WT M41L, M184V, L210L/W, T215Y 28 weeks of M184V only 5000 c/mL ABC=6.2, ZDV=12.2 fold 400 c/mL ABC=5.9, ZDV=4.1fold 50 c/mL

  13. Should we worry about drug resistance • USA: 1999 an estimated 87% of patients with detectable viremia receiving treatment with ARVs had evidence of genotypic mutations associated with HIV resistance to at least one drug (70% for NRTI, 31% for NNRTI and 42% for protease inhibitors) • In recently infected individuals resistance prevalence ranges between 10-25% in some communities in Europe and USA

  14. Review of drug resistancein Uganda

  15. Some information on resistance in Uganda • Drug naïve: • Becker-Pergola et al. AIDS Res Hum Retro 2000 • Weidle PJ et ak JAIDS 2001 • Richard N et al. ARHR 2004 • Gale C et al. ARHR 2006 NO resistant mutations but appreciable polymorphisms-minor mutations that could have relevance in resistance development • Transmitted resistance: • Ndembi N et al ARHR In press (No resistance mutations)

  16. CD4 count Viral load VL 1000 MONTHS YEARS Treatmentonset Virologicalfailure(>1000 c/ml) Clinical failure(AIDS events) INCREASING RESISTANCE POTENTIAL IMPLICATIONS OF ART WITHOUT VIROLOGICAL MONITORING: FAILURE OF THERAPY

  17. Dart virology studies • 300 patients on Combivir + Tenofovir • 100 in each of 3 clinical sites in Uganda (2) and Zimbabwe (1) • 50 with baseline CD4 <100 cells/mm3, 50 CD4 (100-199) • Plasma HIV-1 RNA assayed on stored specimens at 0, 4, 12, 24 and 48 weeks after initiation of CBV+TDF • Genotyping of those with VL >1000c/ml is underway

  18. Evolution of resistance 24-48 weeks (n=7) AZT + 3TC + TDF

  19. Impact of viral subtype on resistance mutations

  20. Differences in the dynamics of viral rebound and evolution of resistance between CBV/NVP and CBV/ABC (NORA sub study of DART Trial) uncovered in the absence of viral load monitoring in real-time. Nicaise Ndembi1, Deenan Pillay2, Ruth Goodall3, Adele McCormick4, Andy Burke3, Fred Lyagoba1, Paula Munderi1, Pauline Katundu5, Stefano Tugume5, Pontiano Kaleebu1 on behalf of the DART Virology and Trial Teams 1 Med Res Council/Uganda Virus Res Inst Prgm on AIDS, Entebbe, Uganda; 2 UCL/Health Protection Agency, London, UK; 3 Med Res Council Clin Trials Unit, London, UK; 4 UCL, London, UK; and 5 Joint Clin Res Ctr, Kampala, Uganda;

  21. Table 1: Prevalence of individual and class specific mutations * occurring with >5% prevalence

  22. On treatment in clinics (JCRC and UNAIDS HIV drug access initiative clinics) • Weidle PJ et al. JAIDS 2001 • Weidle PJ et al. Lancet 2002 • Weidle P.J et al. AIDS 2003 • Richard N et al. ARHRetro 2004 • Oyugi JH et al. AIDS 2007 Note late 1990s some were on dual NRTI therapy, most paying and price high Summary findings: Resistance detected in those with virological failure, mutations were similar to subtype B; phenotypic resistance corresponded to genotypic resistance; treatment interruptions lead to resistance

  23. Resistance under PMTCT(HIVNET 006 & 012) • Jackson JB et al. AIDS 2000; Eshleman SH et al. AIDS 2001; Eshleman SH et al. JAIDS 2004; Eshleman SH et al. ARHR 2004; Eshleman SH et al. JID 2005 • Summary: In women K103N NVP mutation 6-8 weeks after delivery and fades by 12-24 months!! Minor population missed • In infants: Y181C • What will happen when these women and infants start HAART will NVP containing regimens be effective

  24. Is it possible to prevent HIV Drug Resistance? No, NOT ENTIRELY Some degree of HIV drug resistance (HIVDR) is inevitable high rate of mutation treatment is life long

  25. The Country HIVDR PackageNational HIVDR strategy elements for countries scaling up ART • Development of a national HIVDR strategy working group, plan and budget • HIVDR prevention activities • Regular evaluation of HIVDR "early warning" indicators from all ART treatment sites • HIVDR transmission threshold surveys: geographic areas, populations, timing • Sentinel monitoring of HIVDR emerging in treated populations and related ART programme factors • HIVDR database development • A designated HIVDR genotyping laboratory • Preparation of national annual HIVDR report and recommendations

  26. 23rd -24th January 2007, Kampala, Uganda

  27. Goal of Plan • To support ART program practices and country planning in order to minimize the unnecessary emergence of HIV drug resistance, and to restrict the extent to which emerging resistance jeopardizes the effectiveness of the limited ART regimens available, within the context of the national HIV prevention and treatment plan.

  28. Specific Objectives and key activities • Develop an support capacity for HIVDR prevention, monitoring and surveillance • Develop a list of EWI that will be regularly evaluated • Support and coordinate surveillance of HIVDR transmission in different geographical regions • Support and coordinate the monitoring of HIVDR arising in paediatric and adult populations starting and continuing treatment

  29. Objectives continue • Accredit and support local laboratories to support HIVDR activities • Develop and maintain a data management system • ***Develop and maintain a system to disseminate program findings and results for evidence based HIV drug resistance containment strategies ( translate into policy

  30. Some achievements so far • Consensus workshop Jan 2007 • HIVDR working group created • HIVDR transmitted Threshold survey (In press ARHR) • Early Warning Indicators (Pilot completed) • UVRI National reference laboratory final stages of WHO Accreditation • Some equipments and reagents obtained from The Global Fund

  31. QCMD 2007 ENVA7 HIV Drug Resistance Typing Proficiency Programme

  32. Next activities • Sentinel HIVDR monitoring at selected treatment sites • Repeat Threshold transmitted resistance in Kampala and later Mbarara • Collaborate with other partners such as PharmAccess

  33. Data on Early Warning Indicators for HIV Drug Resistance In UgandaDecember 2007 Dr Wilford Kirungi, Dr Elizabeth Madraa, Dr Norah Namuwenge, Dr Frank Lule, Dr Beatrice Crahay, Miss Marion Acieng, Dr Pontiano Kaleebu and The National HIVDR Technical Working group

  34. WHO Recommended HIVDR EWI • The HIVDR TWG prioritised 6 HIVDR EWI and set thresholds for each • Indicator 1: Prescribing practices • Indicator 2: Defaulter rates during the first 12 months of ART • Indicator 3: Retention on first-line during the first 12 months of ART • Indicator 4: Appointment keeping over a 12 months period • Indicator 5: Pill count adherence • Indicator 6: Continuity of ARV drug supply in facilities

  35. Methods • Sample of 41 ART sites during Nov – Dec 2007 • Sampled from all regions, various partners, different levels and modes of ART service delivery that had had ART established for at least 1 year • Trained field workers and constituted 6 teams of 2 • 5 teams comprised of persons with medical training and clinical experience of ART – 28 sites • One team of 2 data managers with IT background and experience in EMRS - 13 sites

  36. Composite Scores

  37. Composite Scores (ctd)

  38. Composite Scores (ctd)

  39. Conclusions • Resistance develops in those who do not suppress virus • We need to study more how resistance develops in absence of virological monitoring • A national ART prevention and monitoring plan is operational • A small study has not demonstrated transmitted resistant viruses • A significant proportion of patients in ART treatment centers start on appropriate ART regimens • Drug stock-out afflict many centers and poses a danger for poor adherence and resistance development

  40. Acknowledgements Dart team: MRV-UVRI; JCRC; IDI; University of Zimbabwe, MRC-CTU; UCL, Imperial College National HIVDR working group WHO MRC Dart virology supported by Roche, GSK, Abbot, Gilead, Boehringer Ingelheim

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