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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

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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

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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

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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

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10

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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

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Start Therapy

† † †

a m l

Time on HAART (days)

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Slide courtesy of Robert Siliciano

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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

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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

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0.1

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10000

100000

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0 100 200 300

Start Therapy

a m

Time on HAART (days)

l

Slide courtesy of Robert Siliciano

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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

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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

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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

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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

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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)

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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

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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

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• 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