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2014 “Towards an HIV Cure” Symposium, Melbourne “The Role of Therapeutic Vaccination in HIV Cure Strategies” Viral Persistence: Obstacles and Opportunities.

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Presentation on theme: "2014 “Towards an HIV Cure” Symposium, Melbourne “The Role of Therapeutic Vaccination in HIV Cure Strategies” Viral Persistence: Obstacles and Opportunities."— Presentation transcript:

1 2014 “Towards an HIV Cure” Symposium, Melbourne “The Role of Therapeutic Vaccination in HIV Cure Strategies” Viral Persistence: Obstacles and Opportunities in Overcoming AIDS Virus Infection J.D. Lifson AIDS and Cancer Virus Program Leidos Biomedical Research, Inc. Frederick National Laboratory AIDS and Cancer Virus Program

2 new-hope-of-a-cure-for- hiv.html?pagewanted=all&_r=0 aids-hero-martin-delaney-dies-california

3 Definitions Reservoir: Virus that persists despite apparently effective suppressive cART, and is capable of giving rise to recrudescent infection if/when cART is stopped Cure (definitive treatment beyond lifetime cART): Eradication: Elimination through treatment of all virus capable of giving rise to recrudescent infection if/when cART is stopped Functional Cure (sustained off treatment remission): Not complete elimination of reservoir, but reduction of reservoir to levels sufficiently low, with sufficient host control, to limit/abrogate pathogenesis and minimize/eliminate risk of transmission

4 Challenges for HIV Cure Residual virus replication (“active reservoir”) Long lived/self renewing infected cells Latent reservoirs – Epigenetic and transcriptional mechanisms of latency – Anatomic and cell lineage compartments Pharmacological or immunological sanctuary sites Must eliminate or control “last virus” capable of initiating recrudescence

5 Approaches to HIV Cure: Mechanism Based and Empirical cART intensification Transcriptional activators Epigenetic modulators Immune modulators – Cytokines – Immune checkpoints Immune targeting (require viral expression) – mAbs – Adoptive cell therapy (engineered cells; effector, resistance) – Therapeutic vaccination Combinations

6 Dr. Lifson will see you now….

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8 Animal (NHP) Models in HIV Cure Research: Strengths, Role, Limitations Experimental Control and Flexibility Identity, timing, route, amount of viral inoculum; sequence tagged “synthetic swarm” Flexibility for sampling: Blood (incl ‘pheresis), tissues - Longitudinal - Scheduled euthanasia/necropsy cART regimen: Compliance, flexibility for initiation, interruption Flexibility for experimental interventions: Preliminary proof of concept, risk/benefit Monkeys are not people, HIV is not SIV/SHIV

9 cART in NHP Drug Considerations Activity/potency vs. SIV Drug delivery: Dosage, Route (“compliance”) Bioavailability, PK (plasma and tissue levels!) Toxicity Sustainability over experimental duration Drug availability/cost : Regimens able to achieve and sustain suppression of SIVmac239 to < 30 RNA copies/mL

10 Evaluation of Pharmacologic Interventions (HDACi/SAHA) in cART Suppressed NHP (Merck) Test SAHA, establish NHP model cART regimens In vitro/Ex vivo validation – SIV vs. HIV, macaque cells vs. human cells Safety In vivo activity SIVmac239 cARTNecropsy 4 wk wk 3 wk 6-7 wk 3 wk 5-6 wk SAHA 45mg/kg/day SAHA 57 mg/kg/day

11 Ex Vivo SAHA Treatment Increases Histone Acetylation and Induces SIV Expression from CD4+ T Cells From SIV-Infected Macaques on Suppressive cART

12 cART + SAHA in NHP cART treatment for > 1 yr SAHA safe; cumulative 84 doses Treatment effects; histone acetylation, SIV transcriptional ratio (vRNA:vDNA) Results complex; PK/PD; decr. response with repeat dosing Despite activity, extensive dosing, no viral clearance HDACi may have role, but alone unlikely to meaningfully impact reservoirs without other interventions Romidepsin also studied (Gilead); histone acetylation, incr PVL, but not viral clearance Similarities to emerging clinical data support utility/relevance of NHP models

13 Activity (potency, specificity) PK/PD Fractional hit rate per dose/cycle Interpretation/significance of readouts Fate of “induced” cells Toxicity/off target effects Must eliminate/control “last virus”; potential role for immune surveillance, immune clearance Role for therapeutic vaccination? Cellular vs. Ab HIV Cure: Limitations of “Pharmacological Only” Approaches

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15 HIV Cure: Therapeutic Vaccination (TVX) Limitations of conventional TVX: Kinetics: – Transient vaccine Ag – Later responses depend on Ag from infection; responses chase the virus Specificity: – Limited breadth vs. sequence diversity, viral plasticity – MHC allele dependence – Potential boosting of responses to already escaped epitopes

16 And now, for something completely different….

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18 Extremely high frequency of CD4+ and CD8+ T cell responses Effector memory biased Indefinitely persistent Widely distributed, incl mucosal effector sites, viral portals of entry Capable of locally containing, aborting infection? Clearly different from other approaches; even if it doesn’t protect, likely to learn something! Exploiting the Evolutionarily Acquired Immune Wisdom of CMV: Predicted Properties of T Cell Responses to CMV-Vectored Vaccines

19 Kinetic Mismatch Barrier for AIDS Vaccines: “Too Little, Too Late” Picker, LJ, Hansen, SG, and Lifson, JD, Ann Rev Med, 2011 Rh-rCMV

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21 “Prophylactic” Rh-CMV/SIV Vaccination: Properties and Mucosal Challenge Cumulative Results No superinfection block Uniquely broad CD4 + (TNF +, IFN-  +, IL-2 +, MIP-1  +  ) and CD8 + (TNF +, IFN-  +, MIP-1  +, CD107 + ) T EM responses Maintained indefinitely Widely distributed, incl mucosal effector sites No NAb responses Post-acquisition control of infection in > 50% of vaccinated macaques

22 rRh-CMV Vectored SIV Vaccines: Additional Findings Unusual breadth of CD4+ and CD8+ T cell responses, but missing responses to immunodominant epitopes “Protected animals” (i.r., ivag) clearly infected; repeat challenged until transient viremia, immune responses to non-vaccine SIV antigens SIV specific CD4 cells not lost Control of infection, not “sterile protection” Durable control with extended follow up

23 Zinkernagel-D’Oh-erty Revisted

24 “…when you have eliminated the impossible, whatever remains, however improbable, must be the truth…” S. Holmes, The Sign of the Four

25 Extremely broad CD8 responses; no canonical immunodominant epitopes, indefinitely persistent 2/3 of CD8 responses restricted by MHC-II, NOT MHC-I Promiscuous Supertopes: Epitopes presented by multiple MHC-II allomorphs; Multiple peptides presented by individual MHC-II allomorphs Atypical MHC-I restricted responses presented by minimally polymorphic MHC-I-E, not MHC-I A,B (nef resistant) RhCMV 68.1 vector dependent alternative antigen priming: Rh189 (US11) Rh157.5, Rh157.4, and Rh157.6 (UL128, UL130, and UL131) Mechanism? Importance for protection? Vectors provide opportunities for response customization ; Unusual Properties of CD8+ T Cell Responses to Rh-CMV/SIV Vaccines

26 130 RhCMV Vector-elicited CD8+ T Cell Responses: Epitope Recognition

27 Viral control after i.r, i.vag., i.v. challenge Control of disseminated infection, not just at portal of entry Progressive decline of infection dependent T cell responses, clearance of virus over time, including from tissue sites “Functional cure” and apparent eradication

28 Longitudinal Analysis of Rh-CMV/SIV Mediated Protection After Intravaginal Infection

29 Longitudinal Analysis of Rh-CMV/SIV Mediated Protection After Intravaginal Infection: Tissue Viral Load SIV RNA SIV DNA

30 Adoptive Transfer to Naïve Hosts: No Evidence of Residual Infectious Virus

31 ?

32 Implications of Apparent Viral Clearance for Therapeutic Vaccination Can TVX with RhCMV/SIV clear infection in SIVmac239 infected macaques on cART? Indefinitely persistent immune surveillance, broad, atypical T cell responses Considerations for evaluation of therapeutic vaccination Effective, sustainable cART in NHP Timing of cART initiation Duration of cART Vaccine immunogenicity in infected NHP on cART Virological readouts (Bx vs. Nx) - qPCR/qRT PCR - Virus recovery culture - Adoptive transfer - cART interruption

33 Therapeutic rhCMV/SIV Immunization In RM Started on cART in Early Chronic SIV Infection SIVmac239X* *Del Prete, Keele BF. et al, J Virol May 7 cART Rh-CMV/SIV Rh-CMV/Empty ATI n=12 n=6 d 0 d 42 d 240 d 330 d ~ 600

34 Immunization Therapeutic rhCMV/SIV Immunization of RM Started on cART in Early Chronic SIV Infection

35 Rh-CMV/SIV Vaccination of SIV-Infected Macaques on cART Increases CD4+ and CD8+ T Cell Responses to Vaccine (gag) but Not Non-Vaccine (vif) SIV Antigens RhCMV/SIV vaccinated (n=12) RhCMV/empty vaccinated (n=6)

36 Timing of cART Initiation Profoundly Influences “Reservoir” Establishment Okoye, et al, submitted

37 Rebound Competent Reservoir Established Early Okoye, et al, submitted

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39 Therapeutic rhCMV/SIV Immunization of RM Started on cART in Acute SIV Infection SIVmac239X* *Del Prete, Keele BF. et al, J Virol May 7 cART Rh-CMV/SIV Rh-CMV/Empty ATI n=17 d 0 d 7-10 d 70 d 160 d ~ 550

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41 Unusual immunology; vector dependent alternate priming Control after infection via i.r., i.vag., i.v. routes Control infection disseminated to tissues, not just portal of entry Indefinitely persistent immune surveillance; progressive viral clearance to functional cure, apparent eradication Extremely broad epitope coverage; epitopes not recognized in natural infection, including promiscuous supertopes; advantages for both prophylactic and therapeutic vaccination Timing of cART initiation Future plans (addtl NHP studies, clinical development): - Prophylactic vaccination - Therapeutic vaccination, with addtl immuno- or pharmacologic interventions to enhance/accelerate viral clearance CMV-Vectored AIDS Virus Vaccines: Summary/Future

42 Viral Persistence in T FH in Follicles: A Potential Obstacle to Complete Viral Clearance Fukazawa, et al, submitted

43 COLLABORATORS Contract HHSN E Louis Picker Scott Hansen Afam Okoye Abigail Ventura Roxanne Gilbride Colette Hughes Julia Ford Matthew Lewis Awbrey Gilliam George Xu Andy Sylwester Haesun Park Shoko Hagen Yoshinori Fukazawa Richard Lum LASP/LBRI/FNL/NCI Jeremy Smedley Rhonda Macallister Mercy Gathuka Solomon Wangari Klaus Fruh Jonah Sacha Patrizia Caposio Jay Nelson Emily Marshall Daniel Malouli Jennie Hines Dan Streblow Michael Axthelm Alfred Legasse Ben Burwitz Shannon Planer Tonya Swanson John Turner Michael Jarvis Christoph Kahl Mike Piatak, Jr. Jake Estes Brandon Keele Greg Del Prete Randy Fast Kelli Oswald Becca Shoemaker Yuan LI Doug Schneider Vicky Coalter Adam Wiles Rodney Wiles Brandi Freemire William Bosche Brian Berkemeier Carolyn Reid Laura Newman Leslie Lipkey RO1 AI060392; P01 AI094417; R01 AI095113; R01 DE ACVP/LBRI/FNL/NCIVGTI/OHSU/ONPRC Daria Hazuda Chris Tan John Wai Rosa Sanchez Romas Geleziunas Joe Hesselgesser Jillian Hattersley Bei Li DMSI/NCI-F Greg Alvord Octavio Quinones


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