welcome to uw i-tech hiv/aids clinical seminar series july 24th, 2008 hiv lifecycle and mechanisms...

Welcome to UW I-TECH HIV/AIDS Clinical Seminar Series

July 24th, 2008

HIV Lifecycle and Mechanisms of Antiretroviral Therapy

David Spach, MD

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HIV/AIDS 2008 Treatment Update

An In-Depth Look at the Viral Life Cycle to Understand Old and New Antiretroviral Medications

David H. Spach, MD

Professor of MedicineDivision of Infectious Diseases

University of Washington, Seattle

HIV/AIDS 2008 Treatment Update

• Overview of HIV Structure and Life Cycle

• 2008 DHHS Antiretroviral Therapy Guidelines

• Mechanisms of Action of Antiretroviral Medications

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HIV Structure and Life Cycle

HIV: Basic Structure

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HIV RNA

HIV: Basic Structure

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gp120 gp41

Envelope

Capsid (p24) HIV RNA

Matrix (p17)

Nucleocapsid (p7)

HIV: Functional Enzymes

• What are the three key HIV enzymes involved in HIV replication?

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HIV Enzymes

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Reverse Transcriptase Integrase Protease

Host (Human) Cell: Key HIV Receptors

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Host Cell

CD4 Receptor

CCR5 Co-Receptor

CXCR4 Co-Receptor

Question

• What genetic alteration in human co-receptors is associated with relative resistance to HIV infection?

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CCR5-∆32

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CCR-∆32

Intracellular Space

Extracellular Space

Host Cell Membrane

CC

CCR5

CC

HIV: Life Cycle

HIV

Nucleus

Host Cell

CD4

CCR5

Host DNA

HIV: Life Cycle

HIV

Nucleus

Host Cell

CD4

CCR5

EntryEntry

1

3

2

HIV: Life Cycle

HIV RNA

HIV

Nucleus

Host Cell

CD4

CCR5

EntryEntry UncoatingUncoating

HIV: Life Cycle

HIV RNA

HIV

Nucleus

Host Cell

CD4

CCR5

EntryEntry UncoatingUncoating Reverse Transcription

Reverse Transcription

HIV DNA

Reverse Transcriptase

HIV: Life Cycle

HIV RNA

HIV

Nucleus

Host Cell

CD4

CCR5

HIV Proviral DNA

EntryEntry UncoatingUncoating Reverse Transcription

Reverse Transcription IntegrationIntegration

HIV DNA

Integrase

HIV: Life Cycle

HIV RNA

HIV

Nucleus

Host Cell

CD4

CCR5

mRNA

gRNA

EntryEntry UncoatingUncoating Reverse Transcription

Reverse Transcription IntegrationIntegration TranscriptionTranscription

HIV DNA

HIV: Life Cycle

HIV RNA

HIV

Nucleus

Host Cell

CD4

CCR5

mRNA

Gag

Gag-Pol

Myr

EntryEntry UncoatingUncoating Reverse Transcription

Reverse Transcription IntegrationIntegration TranscriptionTranscription TranslationTranslation

gp160

HIV DNA Protease

HIV: Life Cycle

HIV RNA

HIV

Nucleus

Host Cell

CD4

CCR5

HIV

mRNA

Gag

Gag-Pol

Myr

EntryEntry UncoatingUncoating Reverse Transcription

Reverse Transcription IntegrationIntegration TranscriptionTranscription TranslationTranslation Assembly &

BuddingAssembly &

Budding

HIV DNA

HIV: Life Cycle

HIV RNA

HIV

Nucleus

Host Cell

CD4

CCR5

HIV

mRNA

Gag

Gag-Pol

Nucleoside RTINucleoside RTIIntegrase InhibitorsIntegrase Inhibitors

Protease InhibitorsProtease Inhibitors

Entry InhibitorsEntry Inhibitors

HIV DNA

Non-Nucleoside RTINon-Nucleoside RTI

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2008 DHHS Antiretroviral Therapy Guidelines

Case History

• A 32-year-old HIV-infected woman returns to clinic to discuss starting antiretroviral therapy. Her CD4 count is 330 cells/m3 and her HIV RNA is 79,000 copies/ml.

• According to the 2008 DHHS Antiretroviral Therapy Guidelines: - When should you start antiretroviral therapy on this patient?

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HIV: Natural History

0

200

400

600

800

1000

0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15Years

CD

4 C

ell C

ou

nt

Year 1

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Acute HIV

Initiating Antiretroviral Therapy

0

200

400

600

800

1000

0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15Years

CD

4 C

ell C

ou

nt

Year 1

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350

500

200

Initiating Antiretroviral TherapyJanuary 2008 DHHS Guidelines

0

200

400

600

800

1000

0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15Years

CD

4 C

ell C

ou

nt

Year 1

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Initiate Antiretroviral Therapy

Consider Antiretroviral Therapy350

500

Source: DHHS Guidelines. www.aidsinfo.nih.gov

Question

• Why do you think we are more enthusiastic about starting antiretroviral therapy earlier now than 2-3 years ago?

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Rationale for Earlier Antiretroviral Therapy

• More effective regimens

• More convenient regimens

• Less toxic regimens

• Expanding data suggesting benefit of earlier therapy

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Case History

• A 32-year-old HIV-infected woman returns to clinic to discuss starting antiretroviral therapy. Her CD4 count is 330 cells/m3 and her HIV RNA is 79,000 copies/ml.

• According to the 2008 DHHS Antiretroviral Therapy Guidelines:

- What regimen would you use?

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DHHS Panel: January 2008 ARV Therapy Guidelines Initial Therapy: Preferred Regimens

Picture

NNRTIEfavirenz

Column B

2-NRTITenofovir/Emtricitabine (Truvada) Abacavir/Lamivudine (Epzicom): for patients who test negative for HLA-B5701

Column A

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PIAtazanavir + Ritonavir Fosamprenavir + Ritonavir BIDLopinavir/ritonavir (Kaletra) BID

Construct Regimen by choosing one component from Column A and one component from Column B

Source: DHHS Guidelines. www.aidsinfo.nih.gov

DHHS Panel: January 2008 ARV Therapy Guidelines Initial Therapy: Alternative Regimens

Picture

NNRTINevirapine

Source: www.aidsinfo.nih.gov

Column B

2-NRTIZidovudine/Lamivudine (Combivir) Didanosine + (Emtricitabine or Lamivudine)

Column A

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PIAtazanavir (unboosted)Fosamprenavir (unboosted)Fosamprenavir + ritonavir qdLopinavir/ritonavir (Kaletra) qd Saquinavir + ritonavir

Construct Regimen by choosing one component from Column A and one component from Column B

Case History

• A 32-year-old HIV-infected woman returns to clinic to discuss starting antiretroviral therapy. Her CD4 count is 330 cells/m3 and her HIV RNA is 79,000 copies/ml.

• According to the 2008 DHHS Antiretroviral Therapy Guidelines:

- How should you ideally monitor after treatment is started?

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Antiretroviral Therapy: HIV RNA MonitoringOptimal Response: HIV RNA < 50 copies/ml

10

100

1000

10000

100000

HIV

RN

A (

log

10)

Antiretroviral Therapy Started

50

Time (Months)

1 2 3 4 5 6 7 8 9

√ CD4

√ CD4 √ CD4

Goal: HIV RNA < 50 copies/mlGoal: HIV RNA < 50 copies/ml

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Entry Inhibitors

HIV: Life Cycle

HIV RNA HIV DNA

HIV

Nucleus

Host Cell

CD4

CCR5

HIV

mRNA

Gag

Gag-Pol

Myr

Entry Inhibitors

HIV: Basic Structure

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gp120

gp41

Envelope

HIV: Envelope

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gp41

HIV

gp120

CD4 Binding Groove

V3 Region

HIV: gp41

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HIV

gp41

Host Cellular ReceptorsCD4, CCR5, & CXCR4

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Host Cell Membrane

CD4 Receptor

Extracellular Space

Intracellular Space

CCR5 CXCR4

HIV Cell Binding and Entry

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HIV

CCR5

CD4 Receptor

CD4 Receptor

Host Cell Membrane

Extracellular Space

Intracellular Space

gp120

HIV Cell Binding and Entry

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Host Cell Membrane

CD4 Receptor

Extracellular Space

Intracellular Space

HIV

CCR5

HIV Cell Binding and Entry

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Host Cell Membrane

CD4 Receptor

Extracellular Space

Intracellular Space

HIV

CCR5

V3 Region

HIV Cell Binding and Entry

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Host Cell Membrane

CD4 Receptor

Extracellular Space

Intracellular Space

HIV

CCR5

HIV Cell Binding and Entry

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Host Cell Membrane

Extracellular Space

HIV

CCR5

CD4 Receptor

Intracellular Space

gp41

HIV Cell Binding and Entry

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Host Cell Membrane

Extracellular Space

HIV

Intracellular Space

gp41

HIV Cell Binding and Entry

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Host Cell Membrane

Extracellular Space

HIV

Intracellular Space

Heptad Repeat 1 [HR1]

Heptad Repeat 2 [HR2]

HR1

HR2gp41

HIV Cell Binding and Entry

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Host Cell Membrane

Extracellular Space

HIV

Intracellular Space

HIV Cell Binding and Entry

DHS/PP

Host Cell Membrane

HIV

HIV Membrane

HIV Cell Binding and Entry

DHS/PP

Host Cell Membrane

HIV

HIV Membrane

R5-Tropic Virus: Binds to CCR5

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R5-Tropic HIV

CCR5

CD4 Receptor

CD4 Receptor

Host Cell Membrane

Extracellular Space

Intracellular Space

CXCR4

V3 Region

X4-Tropic Virus: Binds to CXCR4

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X4-Tropic HIV

CCR5

CD4 Receptor

CD4 Receptor

Host Cell Membrane

Extracellular Space

Intracellular Space

CXCR4

V3 Region

Dual-Tropic Virus: Binds to CCR5 or CXCR4

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Dual Tropic HIV

CCR5

CD4 Receptor

CD4 Receptor

Host Cell Membrane

Extracellular Space

Intracellular Space

CXCR4

V3 Region

Question

• What human co-receptor does the drug Maraviroc block?

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Entry InhibitorsCCR5 Inhibitor: Maraviroc (Selzentry)

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Host Cell Membrane

CD4 Receptor

Extracellular Space

Intracellular Space

R5 HIV

CCR5

Maraviroc

NOTE: Blocks Human Protein

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HIV Co-Receptor Tropism AssayMonogram Biosciences Trofile Assay

Assay Measures HIV Tropism - R5 Tropic - X4 Tropic - Dual Tropic/Mixed Tropic

Utilizes Entire Envelope Gene - Generates pseudoviruses

Viral Load Required - Above 1,000 copies/ml

Detection of Minor Species - Reliably detected at 5-10%

R5-Tropic

X4-Tropic

R5X4 (Dual)-Tropic

Mixed Tropic

HIV-1 Tropism Assay

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$1960

Entry InhibitorsFusion Inhibitor: Enfuvirtide (Fuzeon)

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HIV

Heptad Repeat 1

Heptad Repeat 2

Fusion Peptide

Heptad Repeat 2

Enfuvirtide36 amino acid peptide

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Host Cell Membrane

Extracellular Space

HIV

Intracellular Space

Heptad Repeat 1

Heptad Repeat 2

Fusion Peptide

Entry InhibitorsFusion Inhibitors (Fuzeon)

Enfuvirtide

DHS/PP

Host Cell Membrane

Extracellular Space

HIV

Intracellular Space

Entry InhibitorsFusion Inhibitors (Fuzeon)

Enfuvirtide

DHS/PP

Reverse Transcriptase Inhibitors

HIV: Life Cycle

HIV RNA

HIV

Nucleus

Host Cell

CD4

CCR5

HIV

mRNA

Gag

Gag-Pol

Myr

Nucleoside RTI

HIV DNA

HIV RNAHIV Reverse Transcriptase

Human Nucleotides

Human Cell

HIV Reverse Transcription

HIV Reverse Transcription

HIV RNAHIV Reverse Transcriptase

Human Nucleotides

Human Cell

Nucleoside Reverse Transcriptase Inhibitors (NRTIs)

NRTI

HIV RNAHIV Reverse Transcriptase

Human Nucleotides

Human Cell

Fixed-Drug NRTI Combinations

• Preferred- Tenofovir-Emtricitabine (Truvada)- Abacavir-Lamivudine (Epzicom)

• Alternative- Zidovudine-Lamivudine (Combivir)

Case History

• A 38-year-old HIV-infected woman has a CD4 count of 257 cells/mm3 and a serum creatinine of 1.6. The provider would like to use abacavir + lamivudine.

• What test can you use to screen for abacavir hypersensitivity?

• Are there differences in the incidence of abacavir hypersensitivity in different races?

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From: Gallant JE et al. N Engl J Med. 2006;354:251-60.

TDF + FTC + Efavirenz vs. ZDV + 3TC + Efavirenz Truvada versus Combivir

Patients (N = 517 randomized) - ARV naïve, HIV RNA > 10,000 copies/ml - Randomized trial Regimens (N = 487) - Tenofovir + Emtricitabine + Efavirenz - Zidovudine + Lamivudine + Efavirenz

Study Design Results: 48 Weeks (ITT)

84

7380

70

0

20

40

60

80

100

Pat

ient

s (%

)< 400 < 50

HIV RNA (copies/ml)

TDF + FTC + EFV ZDV + 3TC + EFV

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TDF= TenofovirFTC = EmtricitabineZDV = Zidovudine3TC = LamivudineEFV = Efavirenz

P = 0.002 P = 0.02

HIV: Life Cycle

HIV RNA

HIV

Nucleus

Host Cell

CD4

CCR5

HIV

mRNA

Gag

Gag-Pol

Myr

HIV DNA

Non-Nucleoside RTI

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Non-Nucleoside Reverse Transcriptase Inhibitors (NNRTIs)

NNRTI

Reverse Transcriptase

Tenofovir + Emtricitabine + Efavirenz (Atripla)

• Classification: (2) nRTI + (1) nNRTI

• Dose: 1 pill qd- Tenofovir 300 mg- Emtricitabine 200 mg- Efavirenz: 600 mg

• Meal Restrictions: without food

• Strong data from Study 934

• Adverse Effects: CNS (efavirenz)

Etravirine (Intelence)

• Second Generation NNRTI

• Dose: 200 mg bid

• High genetic barrier of resistance

• Adverse Effects: Mainly Rash (mild)

• Risk of Rash: No Correlation with Prior NNRTI Rash

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Case History

• A 26-year-old HIV-infected man returns to clinic after failing a regimen of tenofovir + lamivudine + efavirenz. His CD4 count is 148 cells/m3 and his HIV RNA is 41,000 copies/ml.

• His genotype shows a M184V mutation (lamivudine resistance) and a K103N mutations (efavirenz resistance).

• Is it likely that he will respond to etravirine?

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Baseline NNRTI Resistance & Response to Etravirine DUET 1 & 2 Studies

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75

60 58

41

25

0

20

40

60

80

100

Pat

ient

s w

ith H

IV R

NA

< 5

0 co

pies

/ml

0 1 2 3 > 4

Baseline Etravirine Associated Mutations

Virologic Response: Week 24

From: Cahn P, et al. 2007 ICAAC. Abstract H-717.

Background - Pooled data from DUET 1 & 2

Patients (N = 599) - ARV experienced & failed NNRTI regimen - 3 or more PI mutations - HIV RNA > 1,000 copies/ml

Etravirine Associated Mutations (n = 13) - V90I - A98G - L100I - K101E/P - V106I, - V179D/F - Y181C/I/V - G190S/A

Study Design

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Integrase Inhibitors

HIV: Life Cycle

HIV RNA HIV DNA

HIV

Nucleus

Host Cell

CD4

CCR5

HIV

mRNA

Gag

Gag-Pol

Myr

Integrase Inhibitors

Spach

Raltegravir Strand Transfer Inhibitor

Enzyme Active SiteDDE Catalytic Triad

Raltegravir (Isentress)Strand Transfer

Inhibitor

Catalytic Core Domain

Integrase Inhibitor

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OBT + Placebo

Eligibility - HIV-infected - Treatment Experienced (Median 10 years)

- HIV RNA > 1,000 copies/ml - Randomized, double-blind - Resistance to 3 classes of ARV drugs

OBT + Raltegravir 400 mg bid

From: Cooper DA, et al. 15th CROI 2008. Abstract 788. Steigbigel R, et al. 14th CROI 2008. Abstract 789.

Raltegravir in ARV-Experienced PatientsBENCHMRK-1 & 2 Studies

BENCHMRK 1: N = 350 (Europe, Asia, Peru)

BENCHMRK 2: N = 349 (North & South America)

1x

2x

From: Cooper DA, et al. 15th CROI 2008. Abstract 788. Steigbigel R, et al. 14th CROI 2008. Abstract 789.

Raltegravir in ARV-Experienced PatientsBENCHMRK-1 & 2 Study: 48 Week Data

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* CD4 counts higher in LPV-RTV arms

39

76

33

63

0

20

40

60

80

100

Pa

tie

nts

(%

)

HIV RNA < 400 copies/ml HIV RNA < 50 copies/ml

OBT + Placebo

OBT + Raltegravir

P < 0.001 P < 0.001

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Protease Inhibitors

HIV: Life Cycle

HIV RNA HIV DNA

HIV

Nucleus

Host Cell

CD4

CCR5

HIV

mRNA

Gag

Gag-Pol

Myr

Protease Inhibitors

HIV: Life Cycle

Nucleus

Host Cell

Host DNA HIV Precursor Polyprotein

HIV Protease

HIV: Life Cycle

Nucleus

Host Cell

Host DNA HIV Precursor Polyprotein

Proteins

HIV Protease

HIV Protease Inhibitor

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Protease Inhibitor

Protease Inhibitor

HIV Protease Inhibitor

Active Site

Recent Studies with Ritonavir-Boosted PIs

• KLEAN Trial- Fosamprenavir + Ritonavir = Lopinavir + Ritonavir (Kaletra)

• CASTLE Trial- Atazanavir + Ritonavir = Lopinavir + Ritonavir (Kaletra)

• GEMINI Trial- Saquinavir + Ritonavir = Lopinavir + Ritonavir (Kaletra)

• TITAN and ARTEMIS Trials- Darunavir + Ritonavir > Lopinavir + Ritonavir (Kaletra)

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Questions

Thank you!Next session: July 31st, 2008

Listserv: itechdistlearning@u.washington.eduEmail: DLinfo@u.washington.edu

Welcome to UW I-TECH HIV/AIDS Clinical Seminar Series

Next session: July 31st, 2008

Marcia Weaver, Debbie Winters, MaryAnn Vitello

Task Shifting