Beyond HAART: Outline. HIV-1 Time Line. Outline. Approaches to HIV Eradication 8/15/2013

Transcription

1 8/5/203 Beyond HAART: Approaches to HIV Eradication I have no financial conflicts of interest to disclose 8 August 203 Adam Spivak MD Visiting Instructor, Division of Infectious Diseases University of Utah School of Medicine 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?. We are likely to see feasible HIV cure strategies in the next 5-0 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) 0% 0% 0% 0% Outline The promise of antiretroviral therapy The limits of antiretroviral therapy HIV persistence and latency The Berlin and Mississippi patients Eradication strategies to date HIV- Time Line First descriptions of a novel immunodeficiency syndrome Pre-HAART Era First descriptions of a novel retrovirus isolated from patients with AIDS HIV- antibody ELISA approved for diagnostic use AZT receives FDA approval for HIV- treatment HAART Era 996 FDA approval of first protease inhibitor, allowing for combination antiretroviral therapy accessed 6 August 202

2 8/5/203. Entry 2. Reverse Transcription What is HAART in 203? Three drugs from two drug classes 2 nucleoside analogs + NNRTI / INSTI / PI -4 pills by mouth daily Well tolerated with minimal side effects 85-90% achieve viral suppression and T cell count recovery 3. Integration Accessed August Maturation 4. Assembly, Budding, Release Viral dynamics on monotherapy Viral dynamics in pts on HAART Start Therapy Treatment failure due to viral resistance is rapid and guaranteed when a single drug is used Start HAART Limit of Detection (50 copies/ml) t /2 = day t /2 = 4 days Eradication in 2 to 3 years? Time on Therapy (days) Time on HAART (days) Slide courtesy of Robert Siliciano Slide courtesy of Robert Siliciano Perelson et al., Nature, 997 Gulick et al., NEJM, 997 Hammer et al., NEJM, 997 Viral dynamics on HAART Patients on HAART are viremic Start HAART Limit of Detection (50 copies/ml) Where is this low-level viremia coming from? Start Therapy m l a Time on HAART (days) Time on HAART (days) Slide courtesy of Robert Siliciano Perelson et al., Nature, 997 Gulick et al., NEJM, 997 Hammer et al., NEJM, 997 Slide courtesy of Robert Siliciano 2

3 8/5/203 How does HAART work? Two competing theories: Mutations conferring resistance to all 3 drugs unlikely to be present on the same genome Combined effect of 3 antiretroviral drugs inhibits ongoing viral replication Does ART block all viral replication from occurring?. 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) 0% 0% 0% 2 3 Intensifying HAART Subjects: patients on stable three drug HAART with undetectable viral loads Effect of intensification Add ATV/r 50 copies/ml 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 copy/ml a Time (weeks) Slide courtesy of Bob Siliciano Dinoso et al, PNAS 2009 ATV levels in study patients Effect of intensification 0 C max Add ATV/r ATV/r LPV/r EFV C min 0 0. Limit of Detection Slide courtesy of Bob Siliciano Time (weeks) 2 Dinoso et al, PNAS HAART Intensification HAART Slide courtesy of Bob Siliciano Phase of study Dinoso et al, PNAS

4 8/5/203 Intensification Results Intensifying Agent Result Reference ATVr / LPVr / EFV No change Dinoso et al., PNAS, 2009 RAL No change McMahon et al, Clin Infect Dis, 200 The Clinical Implications of HIV- Latency We have reached the limit of HAART RAL No change Gandhi et al, PLoS One, 200 RAL No change Yukl et al, AIDS, 200 RAL / T20 No change Archin et al, PLoS One, 200 We have reached the theoretical limit of HAART Treatment intensification will not lead to cure Durand et al. Trends Immunol 202 What are the limits of HAART? Replication competent, untranscribed HIV- 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 Outline The promise of antiretroviral therapy The limits of antiretroviral therapy HIV persistence and latency The Berlin and Mississippi patients Eradication strategies to date Incident infections are outpacing treatment, particularly in resource-limited settings Beyond HAART Patients on HAART are viremic What is the nature of persistent HIV- in the setting of durable suppression of viral replication? Is complete viral eradication possible? Start Therapy m l a Time on HAART (days) Slide courtesy of Robert Siliciano 4

5 Frequency (per 0 6 cells) - 8/5/203 Reservoir Discovery Resting memory CD4 + T cells harbor replication competent HIV- proviral DNA Every patient demonstrated evidence of HIV- proviral DNA in a minority of these cells Range of infected cell frequency = 0.5 to 6.2 cells per 0 6 resting CD4 + T cells (IUPM) 0000 Slow decay of latently infected CD4 + T cells Time to eradication > 73.4 years Time on HAART (years) Slide courtesy of Bob Siliciano Finzi et al., Science, 997 Wong et al. Science, 997 Chun et al., PNAS, 997 Chun et al., Nature Med., 995 Chun et al., Nature, 997 Finzi et al., Nature Med., 999 Siliciano et al., Nature Med., 2003 Understanding the Latent Reservoir Understanding the Latent Reservoir Resting memory CD4 + T cells are the best characterized reservoir of replication competent unexpressed HIV- proviral DNA; others may exist Richman et al, Science 2009 In HAART pts ~ out of 0 6 resting CD4 + T cells harbor HIV- proviral DNA Chun et al, Nature 997 HAART pts treated for >0 years show no decrease in reservoir size Siliciano et al, Nat Med 2003 HIV- 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 20 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 20 5

6 8/5/203 The Berlin Patient 40 y/o man with wellcontrolled HIV presents with AML T cells are 45 /ul and viral load is undetectable over last four years on HAART (CCR5 tropic virus); treated with chemo Is The Berlin Patient cured of HIV Infection?. Yes 2. No 3. Not sure AML relapses and allo-sct performed with HLAidentical 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 % 0% 0% 2 3 In Search of Persistent HIV Summary of Virology Results Sample Measure Lab Consensus Avg levels in Fold BSRI ARTsuppressed difference NIH Sweden UCSD JH UCSF pt 750 in 0 6 > Plasma HIV RNA /- Intermittent + -2 c/ml 2-20 < c/ml PBMC HIV DNA ND in HIV RNA ND in in 0 6 > IUPM - - ND IU in IU in 0 6 >0-000 Rectum HIV DNA + Positive 8 c/0 6 cells in HIV RNA - ND < in in CSF HIV RNA - - ND?? 0. c/ml HIV DNA - ND?? Slide Courtesy of Sarah Palmer Slide Courtesy of Sarah Palmer Summary ) 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, 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. Is The Berlin Patient cured of HIV Infection? A. Yes B. No C. Not sure Slide Courtesy of Sarah Palmer 6

7 8/5/ CROI: The Mississippi Patient 203 CROI: The Mississippi Patient Child born 35 weeks gestation (2.5kg) NVD Mother HIV- rapid test positive during labor No ART during labor (precipitous delivery) Baby transferred to UMMC by 30 hours of age HIV- plasma DNA and RNA positive AZT / 3TC / NVP started at 3 hrs; therapeutic dosing Maternal HIV- Results At delivery Rapid test positive (no previous testing) Standard HIV- 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- Results and Treatment HIV- DNA in peripheral blood (30 hrs of life) positive HIV- RNA in peripheral blood (3 hrs) 9,82 copies / ml AZT/3TC continued and NVP switched to LPV/r at therapeutic dosing Mississippi Patient Follow Up Infant lost to follow up at 8 months of age At 23 months follow up resumes at UMMC Mom reports ART discontinuation at 8 months VL undetectable Standard HIV- ELISA negative Standard HIV- DNA PCR negative Slide capture from Debbie Persaud s presentation CROI 203 Atlanta, GA 7

8 8/5/203 Slide capture from Debbie Persaud s presentation CROI 203 Atlanta, GA Slide capture from Debbie Persaud s presentation CROI 203 Atlanta, GA Mississippi Patient Follow Up Western blot at 24 months (at least 6 months off therapy) are negative HIV- 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 coculture assays Slide capture from Debbie Persaud s presentation CROI 203 Atlanta, GA Was The Mississippi Patient cured of HIV Infection?. 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) Slide capture from Debbie Persaud s presentation CROI 203 Atlanta, GA 0% 0% 0% 0%

9 8/5/203 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 [st] D. Remove the stigma of living with HIV [4th] E. Lessen the risk of infecting others [3rd] Verdult F. IAS 202 Verdult F. IAS 202 9

10 8/5/203 Verdult F. IAS 202 Verdult F. IAS 202 Verdult F. IAS 202 Verdult F. IAS 202 Gene Therapy: How to recapitulate the Berlin patient Myeloablative chemotherapy and GVH are not feasible for most HIV- 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- 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 203 0

11 8/5/203 Directly Targeting the Latent Reservoir 2-4 year follow up: HIV cannot be detected in blood or gut lymphoid tissue ART interruption approved by IRB As of July 203, 8-5 weeks off ART no viral rebound, no detectable virus in blood cells, gut lymphoid tissue Functional cure vs. eradication? time will tell Henrich, IAS 203 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 deacetylation (HDAC inhibitors) have shown promise in multiple screens Durand et al. Trends Immunol 202 Glass Half Full? 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 4 (?) >60,000,000 Number of people cured Number of people infected during HIV- pandemic Archin et al. Nature 202 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