ARV Drug Resistance

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

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

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

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)

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)

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

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

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