welcome to uw i-tech hiv/aids clinical seminar series july 24th, 2008 hiv lifecycle and mechanisms...
TRANSCRIPT
Welcome to UW I-TECH HIV/AIDS Clinical Seminar Series
July 24th, 2008
HIV Lifecycle and Mechanisms of Antiretroviral Therapy
David Spach, MD
DHS/PP
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
DHS/PP
DHS/PP
HIV Structure and Life Cycle
HIV: Basic Structure
DHS/PP
HIV RNA
HIV: Basic Structure
DHS/PP
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?
DHS/PP
HIV Enzymes
DHS/PP
Reverse Transcriptase Integrase Protease
Host (Human) Cell: Key HIV Receptors
DHS/PP
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?
DHS/PP
CCR5-∆32
DHS/PP
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
DHS/PP
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?
DHS/PP
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
DHS/PP
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
DHS/PP
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
DHS/PP
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?
DHS/PP
Rationale for Earlier Antiretroviral Therapy
• More effective regimens
• More convenient regimens
• Less toxic regimens
• Expanding data suggesting benefit of earlier therapy
DHS/PP
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?
DHS/PP
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
DHS/PP
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
DHS/PP
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?
DHS/PP
DHS/PP
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
DHS/PP
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
DHS/PP
gp120
gp41
Envelope
HIV: Envelope
DHS/PP
gp41
HIV
gp120
CD4 Binding Groove
V3 Region
HIV: gp41
DHS/PP
HIV
gp41
Host Cellular ReceptorsCD4, CCR5, & CXCR4
DHS/PP
Host Cell Membrane
CD4 Receptor
Extracellular Space
Intracellular Space
CCR5 CXCR4
HIV Cell Binding and Entry
DHS/PP
HIV
CCR5
CD4 Receptor
CD4 Receptor
Host Cell Membrane
Extracellular Space
Intracellular Space
gp120
HIV Cell Binding and Entry
DHS/PP
Host Cell Membrane
CD4 Receptor
Extracellular Space
Intracellular Space
HIV
CCR5
HIV Cell Binding and Entry
DHS/PP
Host Cell Membrane
CD4 Receptor
Extracellular Space
Intracellular Space
HIV
CCR5
V3 Region
HIV Cell Binding and Entry
DHS/PP
Host Cell Membrane
CD4 Receptor
Extracellular Space
Intracellular Space
HIV
CCR5
HIV Cell Binding and Entry
DHS/PP
Host Cell Membrane
Extracellular Space
HIV
CCR5
CD4 Receptor
Intracellular Space
gp41
HIV Cell Binding and Entry
DHS/PP
Host Cell Membrane
Extracellular Space
HIV
Intracellular Space
gp41
HIV Cell Binding and Entry
DHS/PP
Host Cell Membrane
Extracellular Space
HIV
Intracellular Space
Heptad Repeat 1 [HR1]
Heptad Repeat 2 [HR2]
HR1
HR2gp41
HIV Cell Binding and Entry
DHS/PP
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
DHS/PP
R5-Tropic HIV
CCR5
CD4 Receptor
CD4 Receptor
Host Cell Membrane
Extracellular Space
Intracellular Space
CXCR4
V3 Region
X4-Tropic Virus: Binds to CXCR4
DHS/PP
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
DHS/PP
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?
DHS/PP
Entry InhibitorsCCR5 Inhibitor: Maraviroc (Selzentry)
DHS/PP
Host Cell Membrane
CD4 Receptor
Extracellular Space
Intracellular Space
R5 HIV
CCR5
Maraviroc
NOTE: Blocks Human Protein
DHS/PP
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
DHS/PP
$1960
Entry InhibitorsFusion Inhibitor: Enfuvirtide (Fuzeon)
DHS/PP
HIV
Heptad Repeat 1
Heptad Repeat 2
Fusion Peptide
Heptad Repeat 2
Enfuvirtide36 amino acid peptide
DHS/PP
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?
DHS/PP
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
DHS/PP
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
DHS/PP
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
DHS/PP
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?
DHS/PP
Baseline NNRTI Resistance & Response to Etravirine DUET 1 & 2 Studies
DHS/PP
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
DHS/PP
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
DHS/PP
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
DHS/PP
* 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
DHS/PP
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
DHS/PP
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)
DHS/PP
DHS/PP
Questions
Welcome to UW I-TECH HIV/AIDS Clinical Seminar Series
Next session: July 31st, 2008
Marcia Weaver, Debbie Winters, MaryAnn Vitello
Task Shifting