Resistance Testing – Where Do I Start?

Iván Meléndez-Rivera, MDFellow, American Academy of Family Physicians

Assistant Professor of Family MedicinePonce School of Medicine, Ponce PR, USA

Board Member, American Academy of HIV MedicineFaculty, Florida/Caribbean AETC

Medical Director, Centro Ararat, Inc Ponce PR, USA

Disclosures of Financial RelationshipsThis speaker has significant financial relationships with the following commercial entities to disclose:• Advisory Board or Panel: Gilead, Merck• Consultant: Bristol-Myers Squibb• Grants/Research Support: Abbott, Boehringer,

GlaxoSmithKline, Napo, Pfizer• Speakers Bureau: Abbott, Boehringer, Bristol-Myers Squibb,

GlaxoSmithKline, Merck, Pfizer, Tibotec

This speaker will not discuss any off-label use or investigational product during the program.

This slide set has been peer-reviewed to ensure that there are no conflicts of interest represented in the presentation.

Objectives

• Introduce major resistance mutations for each class of HIV therapy

• Order currently available resistance tests

• Present illustrative case(s) of diagnosing resistance pattern resulting in treatment plan adjustment

Definition of Antiviral Drug’s Resistance • Presence of viral mutations that reduce drug

susceptibility compared with the susceptibility of wild-type viruses.

• Can directly or indirectly interfere with a drug's activity.

• Should be distinguished from other causes of drug failure such as: – Non-adherence– Insufficient drug levels– Drug regimens with intrinsically weak antiviral

activity.

Why does Resistance Develop?

• HIV can develop resistance quickly because:– HIV reverse transcriptase makes errors in matching

bases when converting HIV RNA to DNA– HIV replicates at a rapid rate: 1 to 10 billion viral

particles produced daily– In an untreated infected host, every possible mutation

occurs at least once every 24 hours, some of which may impart drug resistance.

If you have developed resistance to a drug, does that mean that you are resistant to ALL the drugs in

the same class?

A. TrueB. False

A. B.

80%

20%

When does resistance occur?

• Resistance occurs when the virus has an opportunity to replicate in the presence of sub-inhibitory concentrations of drugs.

– Treatment with <3 active drugs– Inappropriate selection of drugs

• Pharmacokinetics or drug-drug interactions lead to inadequate drug exposures

– Non-adherence to the treatment regimen• Interruption of treatment (even for a few days)

– Adding one drug to a failing regimen– Prolonging a failing regimen

Selective Pressures of Therapy

Selection of resistant quasispecies

Incomplete suppression• Inadequate potency• Inadequate drug levels• Inadequate adherence• Pre-existing resistance

Vira

l loa

d

Time

Drug-susceptible quasispeciesDrug-resistant quasispeciesTreatment begins

What is viral resistance?

• A continuum of reduced susceptibility of HIV to the inhibitory effects of drugs

More Susceptible More Resistant

The terms "drug resistance" and "reduced drug susceptibility" have similar meanings, provided that each term is viewed as representing a continuum between susceptible and highly resistant. Because antiretroviral drugs differ in their potencies, reductions in susceptibility must be related to the activity of the drug against wild-type viruses.

WILD VIRUS VS MUTANT VIRUS

Why is it important to measure drug resistance?

What is wild-type virus?• HIV virus that has not been exposed to

drug therapy• The predominant sequence of nucleotide

bases in a heterogeneous mixture of virions

• It is the most fit form of HIV in the absence of drug

Identifying Mutations

• How do we identify a resistance mutation?

M 184 M

“184 is the codon position”M is the “wild-type” amino acid (AA)

Identifying Mutations

• How do we identify a resistance mutation?

M 184 V

“184 is the codon position” V is the mutant AAM is the “wild-type” amino acid

• To the virus, mutations can be:

What is the Impact of HIV Mutations?

Decreasing the virus’ ability to survive and/or replicate (viral fitness) or may make the virus hypersusceptible to certain antiretrovirals (ARVs)

No effect on virus function

Changing the structure of the virus to evade antiretroviral treatment. These mutations may or may not affect viral fitness

Johnson VA, et al. Topics in HIV Medicine. 2009;17:138-145.

HIV RNA mutant

Drug resistant

Single-base Mutations May Confer Antiretroviral Resistance

123Position AA:

123 Mutant

AA: Y

YWild-type

AA: X

X

3 nucleotides specify an amino acid

Single-base mutation

HIV RNA wild type

Hoffman C et al. HIV Medicine 2007. 15th ed. Paris, France: Flying Publisher. 2007.

AA=amino acid

Resistance Profile and Potential for Cross Resistance

HIV RNA Mutant

Drug A

Drug B

Drug C

Drug D

B cross resistance

A & B & C cross resistance

Adapted from: Paredes R, et al. Antiviral Res. 2010 Jan;85(1):245-65.

Region of HIV RNA associated with antiretroviral drug class specific resistance

How is resistance measured?

By Genotype• Amino acid substitution on chainBy phenotype (IC50)• IC50

– The minimum concentration of a drug needed to inhibit the growth of the virus by 50% in vitro

• IC50 is analogous to MIC90

– IC90 is not sufficiently reproducible for routine clinical use

• The lower the IC50, the more potent the drug

RESISTANCE MUTATIONS PER HIV CLASS THERAPY

Available Antiretroviral Agents

Nucleoside ReverseTranscriptase Inhibitors (RTIs)• Zidovudine (ZDV)• Didanosine (ddI)• Zalcitabine (ddC)• Stavudine (d4T)• Lamivudine (3TC)• Abacavir (ABC)• Emtricitabine (FTC)• Tenofovir DF (TDF)

Nonnucleos(t)ide RTIs• Nevirapine (NVP)• Delavirdine (DLV)• Efavirenz (EFV)• Etravirine (ETR)• Rilpivirine (RPV)

Protease Inhibitors• Saquinavir (SQV)• Ritonavir (RTV)• Indinavir (IDV)• Nelfinavir (NFV)• Amprenavir (APV)• Lopinavir/r (LPV/r)• Atazanavir (ATV)• Fosamprenavir (Fos-APV)• Tipranavir (TPV)• Darunavir (DRV)

Boosters• Ritonavir (RTV)• Cobicistat (cobi)

Fusion Inhibitor• Enfuvirtide (T-20)

CCR5 Antagonist• Maraviroc (MVC)

Integrase Inhibitors• Raltegravir (RAL)• Elvitegravir(ELV)*• Dolutegravir (DTG)*

* In expanded access

August 28, 2012

Nucleoside Reverse Transcriptase Inhibitors (NRTI’s)

• Zidovudine (ZDV)• Didanosine (ddI)• Stavudine (d4T)• Lamivudine (3TC)• Abacavir (ABC)• Tenofovir (TDF)• Emtricitabine (FTC)

Structure of a covalently trapped catalytic complex of HIV-1 RT published by Huang H et al, Science 1998. http://hivdb.stanford.edu/pages/3DStructures/rt.html Accessed Sept 3, 2012

NRTI’s Resistance Mutations

Adapted from: http://hivdb.stanford.edu/DR/NRTIResiNote.html. Accessed Sept 3, 2012

Red: Primary Mutations to confer resistance Gray: Secondary Mutations***: Increase susceptibility

NRTI’s Signature MutationsMutation Medication with decrease susceptibility

M184V Lamivudine (3TC) and Emtricitabine (FTC)

K65R Tenofovir (TDF)

L74V Abacavir (ABC) and Didanosine (ddI)

Y215F Zidovudine (ZDV) and Stavudine (d4T)

T69ins or Q151M

All except, Lamivudine (3TC) and Emtricitabine (FTC)

Not ALL mutations are bad• M184V/I cause high-level resistance to 3TC

and FTC and low-level resistance to ddI and ABC.

• M184V/I are not contraindications to continued treatment with 3TC or FTC because they increase susceptibility to AZT, TDF, and d4T and are associated with clinically significant decreased HIV-1 replication.

http://hivdb.stanford.edu/DR/cgi-bin/rules_comments_hivdb.cgi?class=NRTI

Non-Nucleoside Reverse Transcriptase Inhibitors (NNRTI’s)

• Nevirapine (NVP)• Efavirenz (EFV)• Etravirine (ETR)• Rilpivirine (RPV)

Non-nucleoside RT inhibitor (NNRTI)-resistance mutationshttp://hivdb.stanford.edu/pages/3DStructures/rt.html Accessed Sept 3, 2012

NRTI’s Resistance Mutations

Adapted from: http://hivdb.stanford.edu/DR/NRTIResiNote.html. Accessed Sept 3, 2012

Red: Highest Levels of resistance Gray: Intermediate level of resistance

NNRTI’s Signature Mutations

Mutation Medication with decrease susceptibility

K103N Efavirenz (EFV) and Nevirapine (NVP)

Y181I/V Etravirine (ETR) and Rilpivirine (RPV)

Y188L Rilpivirine (RPV)

K101P ALL NNRTI

Protease Inhibitors (PI’s)

Saquinavir (SQV) Ritonavir (RTV) Indinavir (IDV) Nelfinavir (NFV) Lopinavir/r (LPV/r) Atazanavir (ATV) Fosamprenavir (FPV) Tipranavir (TPV) Darunavir (DRV)

Major protease inhibitor (PI)-resistance mutationshttp://hivdb.stanford.edu/pages/3DStructures/rt.html, Accessed Sept 3, 2012

PI’s Resistance Mutations

Adapted from: http://hivdb.stanford.edu/DR/NRTIResiNote.html. Accessed Sept 3, 2012

Red: Highest Levels of resistance Gray: Intermediate level of resistance

PI’s Signature Mutations

Mutation Medication with decrease susceptibility

D30N Nelfinavir (NFV)

I50L Atazanavir (ATV)

I47V ALL except Saquinavir (SQV)

I54V ALL except Darunavir (DRV)

I84V ALL except Darunavir (DRV)

Integrase Inhibitors (INI)

Raltegravir (RAL)Elvitegravir(ELV)Dolutegravir(DTG)*

* Investigational

http://www.scientistlive.com/European-Science-News/Pharmacology/HIV_integrase_inhibitor_effective_when_beginning_treatment/23101/ Accessed 06/OCT/12

INI Resistance Mutations

Adapted from: http://hivdb.stanford.edu/DR/NRTIResiNote.html. Accessed Sept 3, 2012

Red: Highest Levels of resistance Gray: Intermediate level of resistance

INI Signature Mutations

Mutation Medication with decrease susceptibility

Q148H/K/R Raltegravir (RAL) and Elvitegravir(ELV)

* In expanded access

Fusion Inhibitors (FI)

Enfuvirtide (T-20)

www.fuzeon.com Accessed Sept 3, 2012

Fusion Inhibitor Resistance Mutations

Adapted from: http://hivdb.stanford.edu/DR/NRTIResiNote.html. Accessed Sept 3, 2012

Gray: Intermediate level of resistance

CCR5 Antagonist

Maraviroc (MVC)

Moore J, et al. Proc Natl Acad Sci USA. 2003;100:10598-10602; Yost R, et al. Am J Health-Syst Pharm. 2009;66:715-726 Accessed Sept 3, 2012

CCR5 Antagonist Resistance is Associated withAmino Acid Changes in the V3 Loop of gp120*

• Variable pattern of Maraviroc resistance-associated amino acid substitutions

• No signature mutations have been identified

• Currently, there is no assay available to assess Maraviroc resistance

Change Maraviroc-resistant

Base

Tip

StemStem

Tip

Base

DeletionInsertion

G/A

*Substitutions outside the V3 loop of gp120 may also contribute to reduced susceptibility to Maraviroc

Adapted from Data on file. ViiV Healthcare, RTP, NC.

CCR5-Resistant Virus Recognizes Drug-Bound Receptors

Mutated gp120recognizes CCR5differently

MVCres Virus

MVCresgp120

Binding siteNOT disruptedby maraviroc

Entry

Mori J, et al. 16th IHIVDRW. Barbados, 2007. Abstract 10.

RECOMMENDATIONS FOR DRUG RESISTANCE TESTING

In which one of the following situations would HIV resistance testing NOT usually be recommended?

A. Acute HIV infection, regardless of whether treatment is to be started

B. Chronic HIV infection, at entry into care

C. After discontinuation (>4 weeks) of ARVs

D. Suboptimal suppression of viral load after starting antiretroviral therapy (ART) A. B. C. D.

25%

16%

52%

7%

Trends of Phenotypic 1-, 2-, and 3-Class Resistance

NNRTI=non-nucleoside reverse transcriptase inhibitor; NRTI=nucleoside reverse transcriptase inhibitor; PI=protease inhibitor.

60

50

40

30

20

10

0

2003

2004

2005

2006

2007

2008

2009

2010

60

50

40

30

20

10

0

2003

2004

2005

2006

2007

2008

2009

2010

2-Class Resistance 3-Class Resistance60

50

40

30

20

10

0

2003

2004

2005

2006

2007

2008

2009

2010

1-Class Resistance

Resi

stan

t Sam

ples

(%)

PINNRTINRTI

PI and NRTIPI and NNRTINRTI and NNRTI

Adapted from Paquet A et al. 51st Interscience Conference on Antimicrobial Agents and Chemotherapy; September 17-20, 2011; Chicago, Illinois. Abstract H2-800.

Testing for Drug Resistance• Before initiation of ART:

– Transmitted resistance in 6-16% of HIV-infected patients– In absence of therapy, resistance mutations may decline over

time and become undetectable by current assays, but may persist and cause treatment failure when ART is started

– Identification of resistance mutations may optimize treatment outcomes

– Resistance testing (genotype) recommended for all at entry to care

– Recommended for all pregnant women

• Patients with virologic failure:– Perform while patient is taking ART, or ≤4 weeks after

discontinuing therapy– Interpret in combination with history of ARV exposure

and ARV adherenceCoffey S. Guidelines for the Use of Antiretroviral Agents in Adults and Adolescents: Initiation of Therapy [PowerPoint]. AIDS Education and Training Centers, National Resource Center; March 2012. Available at http://aidsetc.org/aidsetc?page=etres-display&resource=etres-6. Accessed Sept 03, 2012.

Drug Resistance Testing: RecommendationsRECOMMENDED COMMENT

Acute HIV infection, regardless of whether treatment is to be started

To determine if resistant virus was transmitted; guide treatment decisions.If treatment is deferred, consider repeat testing at time of ART initiation.Genotype preferred.

Chronic HIV infection, at entry into care

Transmitted drug-resistant virus is common in some areas; is more likely to be detected earlier in the course of HIV infection.If treatment is deferred, consider repeat testing at time of ART initiation.Genotype preferred to phenotype.Consider integrase genotypic resistance assay if integrase inhibitor resistance is a concern.

Coffey S. Guidelines for the Use of Antiretroviral Agents in Adults and Adolescents: Initiation of Therapy [PowerPoint]. AIDS Education and Training Centers, National Resource Center; March 2012. Available at http://aidsetc.org/aidsetc?page=etres-display&resource=etres-6. Accessed Sept 03, 2012.

RECOMMENDED COMMENTVirologic failure during ART

To assist in selecting active drugs for a new regimen. Genotype preferred if patient on 1st or 2nd regimen; add phenotype if known or suspected complex drug resistance pattern.If virologic failure on integrase inhibitor or fusion inhibitor, consider specific genotypic testing for resistance to these to determine whether to continue them.(Coreceptor tropism assay if considering use of CCR5 antagonist; consider if virologic failure on CCR5 antagonist.)

Suboptimal suppression of viral load after starting ART

To assist in selecting active drugs for a new regimen.

Drug Resistance Testing: Recommendations(2)

Coffey S. Guidelines for the Use of Antiretroviral Agents in Adults and Adolescents: Initiation of Therapy [PowerPoint]. AIDS Education and Training Centers, National Resource Center; March 2012. Available at http://aidsetc.org/aidsetc?page=etres-display&resource=etres-6. Accessed Sept 03, 2012.

RECOMMENDED COMMENT

Pregnancy Recommended before initiation of ART or prophylaxis. Recommended for all on ART with detectable HIV RNA levels.Genotype usually preferred; add phenotype if complex drug resistance mutation pattern.

Drug Resistance Testing: Recommendations(3)

Coffey S. Guidelines for the Use of Antiretroviral Agents in Adults and Adolescents: Initiation of Therapy [PowerPoint]. AIDS Education and Training Centers, National Resource Center; March 2012. Available at http://aidsetc.org/aidsetc?page=etres-display&resource=etres-6. Accessed Sept 03, 2012.

Drug Resistance Testing: Recommendations(4)

NOT USUALLY RECOMMENDED

COMMENT

After discontinuation(>4 weeks) of ARVs

Resistance mutations may become minor species in the absence of selective drug pressure

Plasma HIV RNA <500 copies/mL

Resistance assays cannot consistently be performed if HIV RNA is low

Coffey S. Guidelines for the Use of Antiretroviral Agents in Adults and Adolescents: Initiation of Therapy [PowerPoint]. AIDS Education and Training Centers, National Resource Center; March 2012. Available at http://aidsetc.org/aidsetc?page=etres-display&resource=etres-6. Accessed Sept 03, 2012.

AVAILABLE RESISTANCE TEST

http://www.tumblr.com/tagged/genotype Accessed 06/OCT/12

Genotypic and Phenotypic Resistance Tests

Translation into linear string of amino acids

Folding into functional protein

HIV RNA

Phenotypic assays test this

Genotypic assays test this

Available Tests

• NRTI, NNRTI AND PI– GENOTYPE– Virtual Phenotype– PHENOTYPE

• ENTRY INHIBITORS– PHENOTYPE

• INTEGRASE INHIBITORS– GENOTYPE– PHENOTYPE

• Co-Receptor Tropism Assay– RNA– DNA

General Limitations of Resistance Testing

• Lack of uniform quality controls across different laboratories

• High cost compared with other tests routinely done in HIV care

• Cannot be reliably performed with HIV RNA < 500-1000 copies/mL

• May not be able to detect minority populations of resistant virus if they account for < 20% of the sample—especially common after drug discontinuation

• Resistant strains that are in viral reservoirs also not detected

Reversion to Predominant Wild-Type Virus After Discontinuing ART

Behrens C, Kindrick A, Harrington R. Antiretroviral Resistance Testing in the Management of HIV-Infected Patients [PowerPoint]. Northwest AIDS Education and Training Center; July 2006. Available at http://aidsetc.org/aidsetc?page=etres-display&resource=etres-9. Accessed SEP 3, 2012.Illustration by David Spach, MD

GENOTYPE

Advantages and Disadvantages of Genotype Testing

Advantages• Rapid turnaround

(1-2 wks)• Less expensive than

phenotyping• Detection of mutations

may precede phenotypic resistance

• Widely available• More sensitive than

phenotype for detecting mixtures of resistant and wild-type virus

Disadvantages• Indirect measure of

resistance• Relevance of some

mutations unclear• Unable to detect minority

variants (< 20% to 25% of viral sample)

• Complex mutational patterns may be difficult to interpret

Genotype Report

The Virtual Phenotype

Genotype

ProteaseRTHIV

Access Data

Genotype & Phenotype DataVirtual Phenotype

Wild-type HIV

Resistant HIV

Behrens C, Kindrick A, Harrington R. Antiretroviral Resistance Testing in the Management of HIV-Infected Patients [PowerPoint]. Northwest AIDS Education and Training Center; July 2006. Available at http://aidsetc.org/aidsetc?page=etres-display&resource=etres-9. Accessed SEP 3, 2012.Illustration by David Spach, MD

Advantages and Disadvantages of “Virtual” Phenotype Testing

Advantages

• Similar advantages to genotype (turnaround time, cost, sensitivity)

• Defines resistance based on database of in vivo responses in treated patients

• Uses 2 clinical cutoffs (CCO) to define spectrum of resistance– CCO1: value below which

response expected to be comparable to wild type

– CCO2: value above which most virologic response would be lost

• Indicates which drugs have partial activity

Disadvantages

• Is an estimated phenotype based on the patient’s genotype, not an actual measured phenotype

• Reliability will depend on the accuracy of the genotype

• Available only from 1 vendor

• More expensive than genotype alone

• Methodology of linking genotype to phenotypic database not intuitively obvious—uses a proprietary “virtual phenotype linear regression

PHENOTYPE

Drug Susceptibility Testing

• Involves culturing a fixed inoculum of HIV-1 in the presence of serial dilutions of an inhibitory drug. – The concentrations of drug required to inhibit

virus replication by 50% (IC50) or 90% (IC90) • Drug susceptibility results depend on:

– inoculum size of virus tested– cells used for virus replication– the means of assessing virus replication.

https://www.23andme.com/health/Resistance-to-HIV-AIDS/ Accessed 06/OCT/12

Advantages and Disadvantages of Phenotype Testing

Advantages:

• Provides direct and quantitative measure of resistance

• Methodology can be applied to any antiretroviral agent, including new drugs, for which genotypic correlates of resistance are unclear

• Uses 2 clinical cutoffs (CCO) derived from clinical cohorts to define spectrum of resistance

– CCO1: value below which reduced virologic response is likely

– CCO2: value above which a virologic response is unlikely

• Indicates which drugs have partial activity

• Can assess interactions among mutations

• Accurate with non-B HIV subtypes

Disadvantages:

• Susceptibility cutoffs not standardized between assays

• Clinical cutoffs not defined for some agents

• May be unable to detect minority variants for some mutations (< 20% to 25% of viral sample)

• Complex technology with longer turnaround (~ 3 wks)

• More expensive than genotyping

Integrase Phenotype• Phenotypic integrase resistance assay is commercially available

– Amplification threshold: HIV-1 RNA > 500 copies/mL – Biological cutoff for raltegravir is fold change (FC) > 1.5– Clinical cutoff not yet determined– Report does not detail genotypic mutations

• High assay accuracy demonstrated by IC50 fold change values reported for site-directed mutants

Fransen S, et al. ICAAC/IDSA 2008. Abstract 1214. Accessed SEP 3, 2012 http://www.clinicaloptions.com/HIV/Conference%20Coverage/Washington%202008/Tracks/Experienced/Capsules/1214.aspx

TROPISMS TEST

Typical HIV Co-ReceptorUsage Patterns

R5 VirusesUse only the CCR5 co-receptorMost prevalent in early diseasePredominate throughout infection

X4 VirusesUse only the CXCR4 co-receptorEmerge in later diseaseAssociated with accelerated CD4+ cell decline and disease progression

Dual-Tropic Viruses Use either the CCR5 or theCXCR4 co-receptor

Mixed-TropicVirus Population

Tsibris AMN, Kuritzkes DR. Annu Rev Med. 2007;58:445-459.

Light generated CCR5 UseR5 Virus

No light generatedNo CXCR4 Use

Not an X4 Virus

Demonstration of R5 virus

CCR5 CXCR4

Virus

Virus

Virus

Light is generated on both CCR5 and CXCR4 cell lines

This is a DUAL virus

Demonstration of dual virus

CCR5CXCR4

Virus Virus

This population shows CCR5 AND CXCR4 co-receptor use

This is a mixed population

Demonstration of mixed virus population

CCR5 CXCR4

Virologic Failure With Resistance

Resistant Virus

Vira

l Loa

d

Time on Antiviral Therapy

Virologic failure is defined as the inability of ARV regimen to achieve virologic suppression or occurrence of virologic rebound1

A confirmed viral load >200 copies/mL can be considered virologic failure2

1. AIDSinfo. Glossary of HIV/AIDS-related terms. 7th ed. 2011. Available at http://www.aidsinfo.nih.gov/ContentFiles/GlossaryHIVrelatedTerms.pdf. Accessed November 18, 2011

2. DHHS Guidelines. http://aidsinfo.nih.gov/contentfiles/AdultandAdolescentGL.pdf. Accessed November 18, 2011.3. Clavel F et al. N Engl J Med. 2004;350:1023-1035.

Based on Clavel et al.3

CASE PRESENTATION

The follow factors leads to developing drug-resistance EXCEPT…?

A. Poor drug absorptionB. Poor adherenceC. High drug levelsD. Pre-existing

resistanceE. Interactions with

other drugs, supplements or recreational drugs

A. B. C. D. E.

0% 2%

11%9%

78%

Case 1: 42 y/o AA female• Dx in 2006• Current Medical Hx

– Diabetes– Hyperlipidemia– Hypertension

• Baseline Labs (1/06)– VL: 230,000– CD4: 320 cells/mm3

• Baseline Genotype– Wild-Type

• Pt request a once a day pill ARV and start 5/06 on EFV/TDF/ETC FDC

• Viral Load quickly becomes undetectable and CD4+ counts raises over time

Case 1: 42 y/o AA female

Date VL CD4

11/06 <400 400

05/07 <50 480

05/08 <50 600

05/09 <50 680

11/09 30,000 600

• Patient experiences virologic failure on Nov 2009 while taking EVF/TDF/FTC

• Pt. reports occasional poor adherence due to occasional sleep disturbances and concerns about lipid problems

Case 1: 42 y/o AA femaleWhat would be your next step?

A. Enforce patient adherence and continue with same regimen.

B. Perform Genotype test and keep patient on the same regiment until genotype results.

C. Perform a tropism and Phenotype test and remove patient from medicines because there are toxic.

D. Change patient regiment without any resistance test performed.

A. B. C. D.

11%

0%7%

82%

Case 1: 42 y/o AA femaleWith this genotype result, is Efavirenz still available?

85%

15% A. YesB. No

Case 1: 42 y/o AA female• January 2010 patient was place on EPZ/ATV• Labs 04/10

– CD4: 700 cells/mm3

– VL: <50 copies• Pt. continue with non-detectable (ND) viral load until

04/12– CD4 800 cells/mm3

– VL: 15,000 copies• Resistance testing result.

– NRTI’s: M184V– NNTRI’s: K103N– PI’s: I50L

Based on new resistance pattern (NRTI’s: M184V NNTRI’s: K103N; PI’s: I50L) which statement is true?

A. All NNRT’s are available to use

B. Atazanavir still available for use

C. 3Tc is a full active drugD. Patient loss susceptibility

to rilpivirineE. Keeping patient on

efavirenz will increase the amount of NNRTI mutations and reduce the susceptibility to all other NRTI’s A. B. C. D. E.

10%

21%

38%

18%

13%

Case 2• A 45 year-old man who is highly treatment-

experienced with antiretroviral therapy has virologic failure on tenofovir/emtricitabine and lopinavir/ritonavir.

• His enhanced Trofile assay reveals a dual/mixed-tropic virus.

• His current genotype reveals reverse transcriptase mutations M41l, V90I, K103N, M184V, L210W, T215Y and protease inhibitors mutations V32I, I47V, I54A, V82L, I84V, and L90M.

• In addition, a 2006 genotype also reveled the envelope glycoprotein 41 mutation G36D.

The next BEST antiretroviral regimen for this patient would include which of the following?

A. EnfuvirtideB. MaravirocC. EtravirineD. Ritonavir-boosted

darunavirE. Ritonavir-boosted

tipranavir

A. B. C. D. E.

0%

20%

6%

57%

17%

Bonus Case• A 21 years-old man who acquired HIV through vertical

transmission presents for routine care.

• Recent genotypic analysis reveals a 69 insertion complex and K103N reverse transcriptase mutations and L10I, K20M, M46I, G48V, I50V, N88S and L90M protease mutations.

Which regimen would be the BEST for him?

A. Raltegravir, etravirine, and atazanavir/ritonavir

B. Raltegravir, etravirine, and darunavir/ritonavir

C. Raltegravir, etravirine, and fosamprenavir/ritonavir

D. Raltegravir, etravirine, and indinavir/ritonavir

E. Raltegravir, etravirine, and maraviroc

A. B. C. D. E.

0%

28%

50%

3%

19%

Reference• http://hivdb.stanford.edu/• http://www.hivresistanceweb.com/index.shtml• https://www.iasusa.org/content/hiv-drug-resistance-mutations• Behrens C, Kindrick A, Harrington R. Antiretroviral Resistance

Testing in the Management of HIV-Infected Patients [PowerPoint]. Northwest AIDS Education and Training Center; July 2006. Available at http://aidsetc.org/aidsetc?page=etres-display&resource=etres-9 . Accessed Sept 03, 2012.

• Coffey S. Guidelines for the Use of Antiretroviral Agents in Adults and Adolescents: Initiation of Therapy [PowerPoint]. AIDS Education and Training Centers, National Resource Center; March 2012. Available at http://aidsetc.org/aidsetc?page=etres-display&resource=etres-6 . Accessed Sept 03, 2012.

• http://www.targethiv.org/library/hiv-resistance-intersection-between-treatment-and-prevention. Accessed Sept 03, 2012