Antiretroviral Drug Resistance Basic Knowledge Global Impact Utility of Global Surveillance Anthony Amoroso, MD Assistant Professor of Medicine University of Maryland School of Medicine Institute of Human Virology Chief of Infectious Diseases, VA Maryland Health Care System

“ Living with HIV used to be like playing checkers and now it’s like playing chess.” Becky Trotter, POZ

HIV-1 Viral Dynamics : Basis of resistance In an HIV-1 infected individual, it is estimated that:In an HIV-1 infected individual, it is estimated that: –10.3 x 10 9 virons are produced each day –Average life span of an HIV-1 viron in plasma is 5.6hours –Average HIV-1 generation time is 2.6 days

HIV-1 Viral Dynamics - Mutations Genome Size base pairsGenome Size base pairs Mutation rate of HIV-1 is estimated to be 3.4 x 10 5 per base pair per replication cycleMutation rate of HIV-1 is estimated to be 3.4 x 10 5 per base pair per replication cycle If true, then every mutation at every position on the genome would occur numerous times each dayIf true, then every mutation at every position on the genome would occur numerous times each day

How Quickly Resistance Can Occur Depends on the Viral Load Viral Load Days Before Mutation Arises 300, ,0001 3, ,000 Adapted from Siliciano, 2002

mutations Development of Viral Resistance PATIENT Non adherence Side effects VIRUS High replication rate Error prone Latent reservoir Barrier to resistance DRUG Subtherapeutic concentrations Selective pressure of less potent ARV therapy C trough Intrinsic activity

Viral Resistance is the Outcome of Viral Replication, Mutation and Selection Original Virus Quasispecies Selection Pressure exerted by Drugs HIV RNA Level New Virus Quasispecies Resistant virus Time Minority Quasispecies with reduced susceptibility

Kuritzkes D, et al. AIDS 1996;10: mg BID (n=14) HIV-1 RNA Response in Subjects With M184V (M184V Present by Week 12)

HIVNET-012: Prevalence of NVP Resistance Mutations at 6 to 8 Weeks Postpartum Eshleman SH, et al. 8th CROI; February 4-8, 2001; Chicago, IL. Abstract Mothers (n=111) Infected infants (n=24) % with resistance mutations

Case # 9 – Gulu, Uganda 16 year old female

Pre-ARV HX No previous ARV exposure OIs prior to ARV – Diarrhea and wasting, Genital ulcerative disease Baseline weight – 35 kg WHO stage – III Baseline CD4 – 37 c/mm3 (11/2004) ARV start date – 22/12/04 Baseline labs – Hb – 10.3g/dl, AST – 22, ALT –18, Cr – 0.7

ARV therapy 14 month duration of therapy Start 22/12/04: TDF/3TC/EFV Switch 21/07/0: TDF/FTC/EFV (current)

OIs since ARV start Herpes Simplex Genital Ulcerative Disease Tonsillitis – 22/02/05 Anal sores – 16/11/05 Perinatal viral warts – 14/03/06

Adherence Patient had treatment preparation, home visits and DOT Dispensing frequency – Monthly No subjective history of missed doses in the past 6 months No history of missed refills in past 6 months No history of missed appointments in past 6 months

Viral Load? >750,000 copies/ml

Why? Poor adherence to safe sexual practices is been closely linked to poor adherence to ARVs. Adolescents are notoriously horrible at taking chronic medications

What is major concern in this case? This pt is at high risk for spreading resistance virus. Is secondary prevention counseling going to have any effect on this patient’s behavior?

Surveillance

Rise in ARV Resistance Among Treatment-Naive Patients NNRTIsPIs Patients (%) drug  2 drugs >10-Fold Resistance Little. 8th CROI; 2001; Chicago. Abstract 756 Patients With >10-Fold Resistance N = 408 P =.05P =.001

Percentage NRTI NNRTI PI Reduced Susceptibility (>10 Fold) of Transmitted HIV during Primary Infection 15 Year n Little SJ. 8th CROI, Chicago, #756

Prevalence of Drug Resistance 1080/1906 patients * Assumes no resistance in samples with HIV RNA <500 copies/mL ** Represents 63% of total study population Total Study Population* Population with HIV RNA >500 copies/mL** Richmond

Causes of Resistance: Lessons Learned Learning curve during applications of consensus treatment guidelines –AZT monotherapy –Sequential monotherapy –2NRTI and PI ( i.e. AZT, 3TC and non-boosted PI) Borderline therapeutic drug levels and significant drug interactions High Adherence Requirements

Global resistance in naïve patients study WATCH: Worldwide Analysis of resistance Transmission over time of Chronically and acute infected HIV-1 Patients 1 RT & PI mutations from 6,054 naïve pts Source: Europe 3252, Africa 1162, Asia 653, Latin America 806, North America 290 Results: 8.9% >1 mutation –Europe 11.3%; NA 9.3%, Africa 5.7%, Latin America 5%, East Asia 9.4%, S/SE Asia 5.3%, 1.8% multiclass resistance 1. Bowles E, et al. XVI IAS, Toronto 2006, MOPE0388; 2. Bowles E, et al. 4 th EHDRW, Monte Carlo 2006, #7 Resistance by ARV class

Primary resistance in ARV-naïve adolescents Study of resistance in pts age from 15 US cities (n=55) HIV-infected w/in 180 days using “detuned” assay Genotype (GT) and Phenotype (PT) obtained Major mutations defined by IAS-USA Drug Resistance Mutations Group 1 pt had GT + PT resistance to ARV in all 3 classes 13th CROI, Denver, CO, February 5-8, Viani R, et al. 13th CROI, Denver, CO, February 5-8, Abst. 21 GenotypePhenotype Overall18%22% NRTI4% NNRTI15%18% PI3.6%5.5%

The HIV Family HIV-1 HIV-2 Group: O M N Clade:A,C,FBEOthers (Africa) (US, Europe) (SE Asia) HIV-1 (Cameroon) less pathogenic Levy JA. HIV and the Pathogenesis of AIDS. 2nd ed. Washington, DC: American Society for Microbiology; 1998:

Distribution of HIV-1 Subtypes in Africa Eastern 10.5 North 0.2 A/G C C A Western 5.0 Southern 20.0 Horn 11.0 Central 6.0 A/G

Can Resistance Testing Be Used for Non-Clade B HIV-1 Subtypes? Do the assays yield any results? –Yes, at least for kit-based genotyping assays Do the results have the same interpretation? –Mostly yes –Exception Some secondary PI mutations are more common in non-clade B viruses M36 I, for example, is wild type for clade C

SDNVP and Resistance 2005 Resistance in child: 13% - 52% Resistance in mothers: 39% - 75% resistance –Clade A 19% –Clade D 36% –Clade C 69%

Conclusions Different HIV-1 subtypes seem to possess distinct potentials for drug related resistance mutation acquisition, including alternative routes and substitutions. This may affect the future design of antiretroviral regimens and salvage regimens in distinct areas of the world where non-B isolates dominate the HIV/AIDS epidemic.

Why new strategies are needed to avoid resistance The mainstream strategy of sequencing, as a whole, has not been successful. –Cross-resistance is a major problem and can prevent rational sequencing of drugs –Novel drugs or “new drugs” in a class may not be available or effective once resistance develops

The Impact of Cross Resistance “First shot is your best shot” Regimen Cohort Virologic failure (VL >500 c/ml) Immune and clinical failure (composite) Clinical events 1 st HAART 40%20%5% 2 nd HAART 50%30%24% 3 rd HAART 67%40%25% in EuroSIDA Cohort (n = 8507) Rate of Treatment Failure in EuroSIDA Cohort (n = 8507) Mocroft, et al, Antivir Ther, 2000.

Viral Suppression by Country (by Year 1 Sites)

ART drug resistance mutations in ART experienced patients in Nigeria E. Idigbe, T. Salawu, B. Osotimehin, B. Chaplin, J-L Sankalé, J Idoko, E Ekong, R Murphy, PJ Kanki Nigerian Institute of Medical Research (NIMR), Lagos Nigeria Federal Ministry of Health, Abuja, Nigeria National Action Committee AIDS, Abuja, Nigeria Harvard School of Public Health, Boston, MA, USA Jos University Teaching Hospital, Jos, Nigeria Harvard PEPFAR (APIN Plus), Lagos, Nigeria. Northwestern University, Chicago USA Supported by AIDS Prevention Initiative Nigeria – funded by the Bill & Melinda Gates Foundation, DAIDS-NIAID/NIH, the Federal Ministry of Health and NACA.

Resistance Patterns to the Baseline Regimen of Patients with viral loads greater 3000 c/ml. LamStavNVP TOTAL Res 19% ResIntRes26% ResSuscRes40% Susc Res3% Susc 11% #144

Response to d4T/3TC/NVP in mothers based on previous history of single-dose NVP 68%* 52%* 38%* % With Virologic Suppression N=40 N=119 N=61 N=47 N=143 N=66 *significant Joudain et al. NEJM 4/04

What will we do with surveillance information?

DHHS Guidelines: Recommendations for Using Drug-resistance Assays (Updated 5/04/06) Adapted from DHHS Guidelines (5/04/06). Available at: Accessed May 9, Drug-resistance assay recommended In acute HIV infection* –If the decision is made to initiate therapy at this time, testing is recommended prior to initiation of treatment. A genotypic assay is generally preferred –If treatment is deferred, resistance testing at this time should still be considered In chronic HIV infection* –Drug resistance testing is recommended prior to initiation of therapy. A genotypic assay is generally preferred –Resistance testing earlier in the course of HIV infection may be considered With virologic failure during combination antiretroviral therapy With suboptimal suppression of viral load after antiretroviral therapy initiation *New recommendations as of DHHS Guidelines update 5/04/06.

Base: All treated patients Q data Regimen Selection by Line of Therapy Line of therapy change defined as a switch of any component of the patient’s ARV regimen. n=951 n=601 n=369 n=451 Line of Therapy ISIS market research data, Synovate US HIV Monitor Q Percentage

Public Health Approach to Treatment Utilize 1 st line regimens with predictable mutations and “dead end mutational pattern” Utilize 1 st line regimens which allow for rational 2 nd line therapies Be willing to change 1 st line therapeutic approach based on resistance data despite costs Invest more heavily on community treatment support/adherence programs to ensure high level initial adherence