8/15/2013
1
Beyond HAART:
Approaches to HIV Eradication
8 August 2013
Adam Spivak MD Visiting Instructor, Division of Infectious Diseases
University of Utah School of Medicine
I have no financial conflicts of interest to disclose
Outline
• The promise of antiretroviral therapy
• The limits of antiretroviral therapy
• HIV persistence and latency
• The ‘Berlin’ and ‘Mississippi’ patients
• Eradication strategies to date
Which of the following best describes your opinion about HIV eradication?
1 2 3 4
0% 0%0%0%
1. We are likely to see feasible HIV cure strategies in the next 5-10 years
2. We should keep looking into curing HIV, but it is a long shot
3. Curing HIV should not be a priority and we should focus efforts on treatment and prevention
4. HIV cure is not something I spend much time thinking about (no opinion)
Outline
• The promise of antiretroviral therapy
• The limits of antiretroviral therapy
• HIV persistence and latency
• The ‘Berlin’ and ‘Mississippi’ patients
• Eradication strategies to date
1996
HIV-1 Time Line
1981 1983 1985 1987 1995
First descriptions of a novel immunodeficiency syndrome
First descriptions of a novel retrovirus isolated from patients with AIDS
HIV-1 antibody ELISA approved for diagnostic use
AZT receives FDA approval for HIV-1 treatment
FDA approval of first protease inhibitor, allowing for combination antiretroviral therapy
Pre-HAART Era HAART Era
http://www.time.com/time/covers/0,16641,19961230,00.html accessed 6 August 2012
8/15/2013
2
http://www.cdc.gov/hiv/topics/surveillance/resources/slides/trends/index.htm Accessed 11 August 2011
1. Entry 2. Reverse Transcription
3. Integration
4. Assembly, Budding, Release 5. Maturation
What is HAART in 2013? • Three drugs from two drug classes
• 2 nucleoside analogs + NNRTI / INSTI / PI
• 1-4 pills by mouth daily
• Well tolerated with minimal side effects
• 85-90% achieve viral suppression and T cell
count recovery
Viral dynamics on monotherapy
0.001
0.01
0.1
1
10
100
1000
10000
100000
1000000
0 100 200 300
Time on Therapy (days)
Start Therapy
Slide courtesy of Robert Siliciano
Treatment failure due to
viral resistance is rapid
and guaranteed when
a single drug is used
Viral dynamics in pts on HAART
0.001
0.01
0.1
1
10
100
1000
10000
100000
1000000
0 100 200 300
Time on HAART (days)
Limit of Detection
(50 copies/ml)
Eradication in 2 to 3 years?
t1/2 = 1 day
t1/2 = 14 days
Start HAART
Perelson et al., Nature, 1997 Gulick et al., NEJM, 1997 Hammer et al., NEJM, 1997 Slide courtesy of Robert Siliciano
Viral dynamics on HAART
0.001
0.01
0.1
1
10
100
1000
10000
100000
1000000
0 100 200 300
Time on HAART (days)
Limit of
Detection
(50 copies/ml)
Start HAART
Perelson et al., Nature, 1997
Gulick et al., NEJM, 1997
Hammer et al., NEJM, 1997 Slide courtesy of Robert Siliciano
Where is this low-level
viremia coming from?
Patients on HAART are viremic
0.001
0.01
0.1
1
10
100
1000
10000
100000
1000000
0 100 200 300
Start Therapy
† † †
a m l
Time on HAART (days)
l
Slide courtesy of Robert Siliciano
8/15/2013
3
How does HAART work?
• Combined effect of 3 antiretroviral drugs inhibits ongoing viral replication
• Mutations conferring resistance to all 3 drugs unlikely to be present on the same genome
Two competing theories:
Does ART block all viral replication from occurring?
1 2 3
0% 0%0%
1. Yes – ART stops viral replication and the virus persists by hiding in a dormant state in T cells
2. No – the virus is able to continue to make copies of itself despite ART
3. Not sure (no opinion)
Intensifying HAART
• Subjects: patients on stable three drug HAART with undetectable viral loads
• Intervention: addition of a fourth agent from different drug class than current regimen for two months
• Outcome measure: frequent viral load quantification by single copy assay
Dinoso et al, PNAS 2009
Add ATV/r
Time (weeks)
Effect of intensification
0.1
1
10
100
1000
8 6 2 10 4 -4 0 -2 12
50 copies/ml
1 copy/ml
Dinoso et al, PNAS 2009
a
Slide courtesy of Bob Siliciano
Add ATV/r
Time (weeks)
ATV levels in study patients
8 6 2 10 4 -4 0 -2
0.1
1
10
Limit of Detection
0.01
12
Cmax
Cmin
Dinoso et al, PNAS 2009 Slide courtesy of Bob Siliciano
0.1
1
10
100
1000
0.01
0.001 HAART Intensification HAART
ATV/r LPV/r EFV
Effect of intensification
Phase of study Dinoso et al, PNAS 2009 Slide courtesy of Bob Siliciano
8/15/2013
4
Intensification Results
We have reached the theoretical limit of HAART
Intensifying Agent Result Reference
ATVr / LPVr / EFV No change Dinoso et al., PNAS, 2009
RAL No change McMahon et al, Clin Infect Dis, 2010
RAL No change Gandhi et al, PLoS One, 2010
RAL No change Yukl et al, AIDS, 2010
RAL / T20 No change Archin et al, PLoS One, 2010
Treatment intensification will not lead to cure
Durand et al. Trends Immunol 2012
The Clinical Implications of HIV-1 Latency
We have reached the limit
of HAART
What are the limits of HAART?
• Replication competent, untranscribed HIV-1 proviral DNA is stably integrated into the host genome of resting memory CD4+ T cells in all patients on HAART
• HAART must be continued indefinitely to prevent viral outgrowth and disease progression
• Incident infections are outpacing treatment, particularly in resource-limited settings
Outline
• The promise of antiretroviral therapy
• The limits of antiretroviral therapy
• HIV persistence and latency
• The ‘Berlin’ and ‘Mississippi’ patients
• Eradication strategies to date
Beyond HAART…
What is the nature of persistent HIV-1 in the setting of durable suppression of viral replication?
Is complete viral eradication possible?
Patients on HAART are viremic
0.001
0.01
0.1
1
10
100
1000
10000
100000
1000000
0 100 200 300
Start Therapy
a m
Time on HAART (days)
l
Slide courtesy of Robert Siliciano
8/15/2013
5
Reservoir Discovery
Resting memory CD4+ T cells harbor replication competent HIV-1 proviral DNA
Every patient demonstrated evidence of HIV-1 proviral DNA in a minority of these cells
Range of infected cell frequency = 0.5 to 16.2 cells per 106 resting CD4+ T cells (IUPM)
0.0001
0.001
0.01
0.1
1
10
100
1000
10000
0 1 2 3 4 5 6 7
Time on HAART (years)
Freq
uen
cy
(p
er 1
06 c
ells
)
Slow decay of latently infected CD4+ T cells
-
Time to eradication > 73.4 years
0.00001
Chun et al., Nature Med., 1995 Chun et al., Nature, 1997 Finzi et al., Science, 1997
Wong et al. Science, 1997 Chun et al., PNAS, 1997
Finzi et al., Nature Med., 1999 Siliciano et al., Nature Med., 2003 Slide courtesy of Bob Siliciano
Understanding the Latent Reservoir
• Resting memory CD4+ T cells are the best characterized reservoir of replication competent unexpressed HIV-1 proviral DNA; others may exist
Richman et al, Science 2009
• In HAART pts ~1 out of 106 resting CD4+ T cells harbor HIV-1 proviral DNA
Chun et al, Nature 1997
• HAART pts treated for >10 years show no decrease in reservoir size
Siliciano et al, Nat Med 2003
Understanding the Latent Reservoir
• HIV-1 proviral DNA integrates into actively transcribed genes Han et al, J Virol 2004
Vatakis et al J Virol 2009
• Multiple restrictions on HIV transcription initiate and maintain viral latency – LTR promoter region requires positive feedback loop involving viral Tat
protein Karn, Curr Opin HIV AIDS 2011
– Tat cofactor P-TEFb and cellular transcription factors NF-κB and NFAT are sequestered in cytoplasm in resting T cells
Brooks et al, PNAS 2003
Williams et al, J Virol 2007
Outline
• The promise of antiretroviral therapy
• The limits of antiretroviral therapy
• HIV persistence and latency
• The ‘Berlin’ and ‘Mississippi’ patients
• Eradication strategies to date
Cohen, Science 2011
8/15/2013
6
The Berlin Patient
40 y/o man with well-controlled HIV presents with AML T cells are 415 /uL and viral load is undetectable over last four years on HAART (CCR5 tropic virus); treated with chemo AML relapses and allo-SCT performed with HLA-identical donor cells lacking functional CCR5 gene after TBI, ATG No rebound in plasma viremia, no HIV present in tissues 5 years after treatment
Hutter et al. NEJM 2009
Is The Berlin Patient cured of HIV
Infection?
1 2 3
0% 0%0%
1. Yes
2. No
3. Not sure
In Search of Persistent HIV
Slide Courtesy of Sarah Palmer
Summary of Virology Results Sample Measure Lab Consensus Avg levels in
ART-
suppressed pt
Fold
difference BSRI NIH Sweden UCSD JH UCSF
Plasma HIV RNA - + + +/- Intermittent +
<1 c/ml
1-2 c/ml 2-20
PBMC HIV DNA - - - - ND
≤1 in 106-7
750 in 106 >750-7500
HIV RNA - - - ND
≤1 in 106-7
66 in 106 >66-660
IUPM - - ND
≤1 IU in 107-9
1 IU in 106 >10-1000
Rectum HIV DNA + Positive
8 c/106 cells
780-3300 in
106
97-413
HIV RNA - ND
<1 in 107
21-57 in 106 210-570
CSF HIV RNA - - ND
≤0.1 c/ml
? ?
HIV DNA - ND ? ?
Slide Courtesy of Sarah Palmer
Summary
1) Most assays for HIV were negative: – No HIV DNA or RNA was detected in PBMC – No infectious virus was isolated from peripheral CD4+T
cells – No HIV was detected in CSF fluid or cells
2) However, 3 different labs were able to detect HIV (2 from plasma, 1 from gut) at 4 different time points: – Levels were lower than typical ART-suppressed patients
and close to the limit of the most sensitive assays. – Sequence data are not available from plasma or gut.
3) HIV-specific Ab levels were readily detectable, but detuned assays tended to show a decrease in Ab over time.
Slide Courtesy of Sarah Palmer
Is The Berlin Patient cured of HIV Infection?
A. Yes
B. No
C. Not sure
8/15/2013
7
2013 CROI: “The Mississippi Patient”
2013 CROI: “The Mississippi Patient”
• Child born 35 weeks gestation (2.5kg) NVD
• Mother HIV-1 rapid test positive during labor
• No ART during labor (precipitous delivery)
• Baby transferred to UMMC by 30 hours of age
• HIV-1 plasma DNA and RNA positive
• AZT / 3TC / NVP started at 31 hrs; therapeutic dosing
Maternal HIV-1 Results
• At delivery
– Rapid test positive (no previous testing)
– Standard HIV-1 testing: ELISA and WB positive
– HIV RNA VL = 2,423 copies / ml
– CD4+ T cells = 664 / uL
• Post-partum
– HIV genotype: pan-susceptible clade B virus
Infant HIV-1 Results and Treatment
• HIV-1 DNA in peripheral blood (30 hrs of life)
– positive
• HIV-1 RNA in peripheral blood (31 hrs)
– 19,812 copies / mL
• AZT/3TC continued and NVP switched to LPV/r at therapeutic dosing
Slide capture from Debbie Persaud’s presentation CROI 2013 Atlanta, GA
Mississippi Patient Follow Up
• Infant lost to follow up at 18 months of age
• At 23 months follow up resumes at UMMC
• Mom reports ART discontinuation at 18 months
– VL undetectable
– Standard HIV-1 ELISA negative
– Standard HIV-1 DNA PCR negative
8/15/2013
8
Slide capture from Debbie Persaud’s presentation CROI 2013 Atlanta, GA
Slide capture from Debbie Persaud’s presentation CROI 2013 Atlanta, GA
Slide capture from Debbie Persaud’s presentation CROI 2013 Atlanta, GA
• Western blot at 24 months (at least 6 months off therapy) are negative
• HIV-1 specific CD8 and CD4 T cell immune responses negative
• PCR recovers viral fragments (sequencing underway and not reported to date)
• No virus recovered from viral outgrowth co-culture assays
Mississippi Patient Follow Up
Slide capture from Debbie Persaud’s presentation CROI 2013 Atlanta, GA
Was The Mississippi Patient cured of HIV Infection?
1 2 3 4
0% 0%0%0%
1. Yes – early ART did not allow reservoirs to develop
2. No – the virus is likely to return over time
3. Not relevant - the baby was not infected in the first place
4. Not sure (no opinion)
8/15/2013
9
Outline
• The promise of antiretroviral therapy
• The limits of antiretroviral therapy
• HIV persistence and latency
• The ‘Berlin’ and ‘Mississippi’ patients
• Eradication strategies to date
Why Look For A Cure?
Which of the following is the most compelling reason for an HIV cure?
A. Improve life expectancy of HIV positive
patients
B. Eliminate the burden of daily medications
C. Reduce long-term health problems
D. Remove the stigma of living with HIV
E. Lessen the risk of infecting others
Which of the following is the most compelling reason for an HIV cure?
A. Improve life expectancy of HIV positive
patients [9th]
B. Eliminate the burden of daily medications [7th]
C. Reduce long-term health problems [1st]
D. Remove the stigma of living with HIV [4th]
E. Lessen the risk of infecting others [3rd]
Verdult F. IAS 2012 Verdult F. IAS 2012
8/15/2013
10
Verdult F. IAS 2012 Verdult F. IAS 2012
Verdult F. IAS 2012 Verdult F. IAS 2012
Gene Therapy: How to recapitulate the Berlin patient
• Myeloablative chemotherapy and GVH are not feasible for most HIV-1 patients
• Small trials with lymphoma patients are combining chemotherapy and engineered autologous HSCT
• Zinc-finger endonucleases (ZFN) are human proteins that cleave small unique DNA sequences
• An ongoing trial is harvesting CD4+ T cells from HIV-1 patients and using a CCR5-specific ZFN to render them resistant to infection once re-infused
• Two HIV+ patients undergo allo-HSCT for lymphoma
• Transplant conditioning regimen is non-myeloablative
• ART is continued during and after transplant
• Significant reduction in HIV DNA in cells noted after transplant
engraftment
• Both patients underwent clinically significant episodes of GVHD
Henrich, JID 2013
8/15/2013
11
• 2-4 year follow up: HIV cannot be detected in blood or gut
lymphoid tissue
• ART interruption approved by IRB
• As of July 2013, 8-15 weeks off ART – no viral rebound, no
detectable virus in blood cells, gut lymphoid tissue
• Functional cure vs. eradication? …time will tell
Henrich, IAS 2013
Directly Targeting the Latent Reservoir
Durand et al. Trends Immunol 2012
In vitro models of the latent reservoir allow for screening assays to identify drugs that can reactivate dormant virus If given in combination with HAART these latency-reversing drugs could reduce the size of the reservoir
One class of drugs that inhibit histone de-acetylation (HDAC inhibitors) have shown promise in multiple screens
Archin et al. Nature 2012
A single 400mg dose of the HDAC inhibitor vorinostat was given to patients on HAART PCR assays demonstrate an increase in viral RNA in latently infected cells in all eight patients The latent reservoir size was not measured in this study Further HDACi studies are under way
Glass Half Full?
>60,000,000 Number of people infected during HIV-1 pandemic
Number of people cured (?) 4
Acknowledgements
University of Utah
Sankar Swaminathan Vicente Planelles Alberto Bosque Laura Martins Jeff Chumley
Bea Silva Marylinda Famiglietti
Maria Abad Camille Novis
Patrick Cassiday Peter Ramirez
Johns Hopkins
Robert Siliciano Joel Blankson Janet Siliciano Evelyn Eisele
Robert Buckheit III Jun Lai
Margene Kennedy Adriana Andrade
John Bartlett Joel Gallant Stuart Ray
Charlie Weiner Myron Weisfeldt
UCSF
Steve Deeks Rebecca Hoh Joseph Wong
Peter Bacchetti
Top Related