Alternative Serotype Adenovirus Vectors
Dan Barouch
Desired Features of a Next Generation HIV-1 Vaccine
Candidate
• The RV144 study suggests that the development of a safe and effective HIV-1 vaccine is indeed possible
• Improved vaccine regimens and immunogens will likely be required
• Key features that would be desired in a next generation HIV-1 vaccine include:
Vectors that avoid high levels of vector-specific NAbs and can be combined into a heterologous prime-boost regimen
Antigens that elicit both humoral and cellular immunity and that optimize immunologic coverage of global virus diversity
Adenovirus Serotypes 26 and 35
• Ad26 and Ad35 were selected for clinical evaluation following preclinical studies of a series of group B and D Ad serotypes
• Ad26 and Ad35 are biologically substantially different than Ad5
– Baseline NAb titers (Abbink et al. J. Virol. 2007; 81:4654-4663; Mast et al. Vaccine 2010; 28:950-957)
– Cellular receptors (Abbink et al. J. Virol. 2007; 81:4654-4663)
– In vivo tropism (Waddington et al. Cell 2008; 132:397-409)
– Innate immune profile (Barouch et al., unpublished data)
– Adaptive immune phenotype (Liu et al. J. Virol. 2008; 82:4844-4852; Ahmed et al., unpublished data)
• High Ad5 NAb titers have been shown to suppress the immunogenicity of Ad5 vaccine vectors
• Ultimate vaccine target populations
• Infants (N=149; South Africa)
• Schoolchildren (N=185; South Africa)
• Initial clinical trial populations
• Adults (N=199; Africa, low-risk community)
• Adults (N=263; Kenya, high-risk IAVI 01B)
• Adults (N=242; Uganda, low-risk RV172)
• Adults (N=438; Thailand, high-risk VAX003)
• Adults (N=222; United States, low-risk IPCAVD001)
• Adults (N=727; United States, high-risk VAX004)
• Adults (N=405; North/South America, high-risk STEP)
• Adults in Rwanda and South Africa pending
International Ad Seroepidemiology:
Baseline Ad26 and Ad35 NAb Titers Are Substantially
Lower than Ad5 NAb Titers in Multiple International
Ad NAb Titers in Highest Seroprevalent Regions:
High-Risk Populations in Kenya and Thailand
Ad5 Ad26 Ad35
10 100 1000 10000 100000 Ad NAb T it e r
Ad5 Ad26 Ad35
10 100 1000 10000 100000 Ad NAb T it e r
Ad NAb Titers in High-Risk Populations in South Africa:
Interim Analysis of 240 of 1,500 Samples
South Africa (N=240; MIRA)
Ad5 Ad26 Ad35
10 100 1000 10000 100000 Ad NAb T it e
r Titer Ad5 Ad26 Ad35
<18 9 51 89
18-200 26 43 10
200-1000 40 5 2
No Suppression of 4x10
10vp Ad26-Gag/Pol/Env/Nef
in Rhesus Monkeys Pre-Immunized with Ad26-Empty
(Baseline Ad26 NAb Titers 18-200)
0 200 400 600 800 1000 1200 253 265 380 381 383 385 326 459 474 182 218 316 Low Ad26 NAb (18-200) Naïve
SFC / 1 0^ 6 PBMC Gag Pol1 Pol2 Env1 Env2 Nef
IFN-γ ELISPOT Responses at Week 2 Following Immunization
87 191 116 141 34 41 <18 <18 <18 <18 <18 <18 Ad26 NAb Titer
9
V520-018: MRKAd5 gag ELISPOT (SFC/106 PBMC) vs. Baseline Ad5 Titer
by Dose Level (North/South America, Caribbean, South Africa, Thailand)
1x10 9 vp/d gag E LI S P O T 50 500 4608 ≤ 18 200 1000 1 3 10 30 100 300 1000 3000 1 slope = -0.25 p-value < 0.001
Baseline Ad5 Titer
1x10 10 vp/d
50 500 4608
≤ 18 200 1000
slope = -0.03 p-value = 0.558
Baseline Ad5 Titer
1x10 9 vp/d gag E LI S P O T 50 500 4608 ≤ 18 200 1000 1 3 10 30 100 300 1000 3000 1 slope = -0.34 p-value < 0.001 Baseline Ad5 Titer
ELISPOT positive ELISPOT negative
1x10 10 vp/d 50 500 4608 ≤ 18 200 1000 slope = -0.05 p-value = 0.281 Baseline Ad5 Titer Study Week 8 Study Week 30
10
V520-018: MRKAd5 gag ELISPOT (SFC/106 PBMC) vs. Baseline Ad5 Titer
by Dose Level (North/South America, Caribbean, South Africa, Thailand)
1x10 9 vp/d gag E LI S P O T 50 500 4608 ≤ 18 200 1000 1 3 10 30 100 300 1000 3000 1 slope = -0.25 p-value < 0.001
Baseline Ad5 Titer
1x10 10 vp/d
50 500 4608
≤ 18 200 1000
slope = -0.03 p-value = 0.558
Baseline Ad5 Titer
1x10 9 vp/d gag E LI S P O T 50 500 4608 ≤ 18 200 1000 1 3 10 30 100 300 1000 3000 1 slope = -0.34 p-value < 0.001 Baseline Ad5 Titer
ELISPOT positive ELISPOT negative
1x10 10 vp/d 50 500 4608 ≤ 18 200 1000 slope = -0.05 p-value = 0.281 Baseline Ad5 Titer Study Week 8 Study Week 30
• Ultimate vaccine target populations in South Africa
• Ad26 and Ad35 seroprevalence in infants negligible
• Ad26 and Ad35 seroprevalence in adolescents low
• Adult clinical trial populations in US, Africa, and Asia
• Ad seroprevalence higher in adults than children; higher in Africa/Asia than the US; higher for Ad26 than Ad35
• Ad35 seroprevalence low in all regions
• Ad26 seroprevalence substantial in Africa and Asia, but median Ad26 NAb titers 10-fold lower than Ad5 NAb titers
• Similar to recent Merck, HVTN, VRC, U. Penn. studies
• These relatively low NAb titers were minimally suppressive in rhesus monkeys for Ad26 and in humans for Ad5
• These data support further clinical development of Ad26 and Ad35 vectors for HIV-1 in the developing world
International Ad Seroepidemiology:
Conclusions
12 Ahmed, Tan, et al. unpublished
Increased CD127, CD62L, Bcl-2 on T Lymphocytes Elicited
by Ad26-Gag and Ad35-Gag Compared with Ad5-Gag in Mice
38% 2% 60% 47% 49% 4% 57% 38% 5% 49% 37% 5% Ad5 Ad26 Ad48 Ad35 Single – IFN-γ Double – IFN-γ/TNF-α IFN-γ/IL-2 Triple – IFN-γ/TNF-α/IL-2 69% 12% 19% 66% 13% 21% Ad26/35 Ad35/26
Improved Functionality of T Lymphocytes Elicited by
Ad26-Gag and Ad35-Gag Compared with Ad5-Gag in Mice
Ahmed, Tan, et al. unpublished
Improved Proliferative Potential of T Lymphocytes Elicited
by Ad26-Gag and Ad35-Gag Compared with Ad5-Gag in Mice
• Antigen-specific T lymphocytes elicited by Ad26 and Ad35:
• Re-express memory markers (CD127, CD62L, Bcl-2) at a higher frequency compared with Ad5
• Demonstrate increased functionality compared with Ad5
• Exhibit substantially increased proliferative potential compared with Ad5 in liver memory recall studies
• Quality may be more important than quantity of responses
• Antigen-specific T lymphocyte functionality and proliferative potential were further enhanced with Ad35-Ad26 regimens
Ahmed, Tan, et al. unpublished
Adaptive Immune Phenotypes Elicited by Ad
Vectors: Conclusions
Substantial Biological Differences Among Ad5, Ad26,
and Ad35 Vaccine Vectors
Ad5 Ad26 Ad35
• Virus Subgroup Group C Group D Group B
• Seroprevalence1 High Intermediate Low
• NAb Titers1 High Low Low
• Cellular Receptor2 CAR CD46 CD46
• Tropism3 Hepatic Non-hepatic Non-hepatic
• DC Maturation4 Low Intermediate High
• Innate Profile5 Proinflammatory Type I IFN Type I IFN
• Adaptive Phenotype6 IFN-γ Polyfunctional Polyfunctional
• Immunologic Potency7 High High Intermediate
• NHP Protective Efficacy7+ ++ +
• Human Safety8 ? (phase 2b) + (phase 1) + (phase 1)
• Human Immunogenicity8++ ++ +
References:1Thorner et al. J. Clin. Microbiol. 2006 44:3781-3783, Abbink et al. J. Virol. 2007 81:4654-4663, Mast et al.
Vaccine 2010 28:950-957, Barouch et al. submitted; 2Vogels et al. J. Virol. 2003 77:8263-8271, Abbink et al. J. Virol.
2007 81:4654-4663; 3Waddington et al. Cell 2008 132:397-409; 4Lore et al. J. Immunol. 2007 179:1721-1729;5Barouch
et al. unpublished; 6Liu et al. J. Virol. 2008; 82:4844-4852, Ahmed et al. unpublished; 7Liu et al. Nature 2009;
457:87-91; 8Buchbinder et al. Lancet 2008 372:1881-1893, Catanzaro et al. J. Infect. Dis. 2006 194: 1638-1649, Barouch et al.
HIV-1 Vaccine Clinical Development Strategy
1. Develop “prototype” novel Ad vectors expressing a single test antigen (VRC EnvA) for a rapid assessment of vector safety and immunogenicity in humans
2. Develop “complete” vaccine products involving optimal
heterologous prime-boost regimens expressing multiple HIV-1 antigens (mosaic Gag/Pol/Env) for clinical development
IPCAVD 001
A phase 1 randomized, double-blind, placebo controlled
dose escalation clinical trial to evaluate the safety and
immunogenicity of recombinant adenovirus serotype 26
HIV-1 vaccine (
Ad26.ENVA.01
) in healthy, HIV-1
uninfected adults
PI: Lindsey Baden, Brigham & Women’s Hospital
Ad26.ENVA.01 (rAd26): Recombinant adenovirus serotype 26 vector
vaccine is a recombinant product composed of an adenovirus serotype 26
vector (∆E1/E3) that encodes a modified gp140 HIV-1 Clade A Env
Protocol Schema and Study Objectives
• Primary Objective:
– To evaluate the safety and tolerability of Ad26.ENVA.01
• Secondary Objective:
• Data remains blinded vaccine vs placebo
• No serious adverse events (SAEs) and no pattern of vaccine-associated adverse events (AEs) in any group
• Minimal to no reactogenicity in the 109 vp and 1010 vp groups
• In the 1011 vp group, 7 subjects exhibited moderate (N=5) or
severe (N=2) reactogenicity following initial vaccination
– Fatigue, myalgia, chills
– Mild fever of 100.5 F (38.0 C) in one subject
– In all subjects, symptoms resolved within 24-48 hours
– Did not recur after second vaccination
• Reduced frequency and severity of reactogenicity in the 5x1010
vp group as compared with the 1011 vp group
• Reactogenicity with 1011 vp Ad26 comparable with that reported
with 1011 vp Ad5
• Merck Ad5 (Priddy et al. CID 2008; 46:1769-1781)
– 58% HA, 42% chills, 47% fever
• VRC Ad5 (Cantanzaro et al. JID 2006; 194:1638-1649)
– 60% moderate reactogenicity, 40% fever
• Ad26 vaccine safe and generally well tolerated to date at all doses studied
• Data remains blinded vaccine vs placebo
• 36 subjects (10 vaccinees, 2 placebos per group):
– Group 1: 109 vp
– Group 2: 1010 vp
– Group 3: 1011 vp
• Samples (laboratory coded to maintain blinding):
– Immunogenicity assays at weeks 0, 2, 4, 6, 8, 24, 26, 28, 52
– Vaccines administered at weeks 0, 4, 24
• Immunologic Assays:
– EnvA ELISA assay
– EnvA IFN-γ ELISPOT assay (validated)
EnvA ELISA Responses – Group 1 (10
9vp)
No Response: samples #1 and #12
EnvA ELISA Titer
Mean Median Week 6: 1,380 1,778 Week 24: 217 300 Week 26: 6,138 5,623 Week 52: 1,278 1,000 1.0 2.0 3.0 4.0 5.0 1 2 3 4 5 6 7 8 9 10 11 12 Log E nv A E LI S A Ti te r 0 2 4 6 8 24 26 28 52 No Response No Response week 0 2 4 6 8 24 26 28 52 1.0 2.0 3.0 4.0 5.0 Week Log E nv A E LI S A Ti te r
• Consistent Env Ab titers following week 0 and week 4 prime
EnvA ELISA Responses – Group 2 (10
10vp)
No Response: samples #14 and #23
1.0 2.0 3.0 4.0 5.0 13 14 15 16 17 18 19 20 21 22 23 24 Log E nv A E LI S A Ti te r 0 2 4 6 8 24 26 28 52 No Response No Response week *
* samples not available
0 2 4 6 8 24 26 28 52 1.0 2.0 3.0 4.0 5.0 Week Log E nv A E LI S A Ti te r
EnvA ELISA Titer
Mean Median
Week 6: 3,436 3,000
Week 24: 509 300
Week 26: 12,654 10,000
Week 52: 2,726 3,000
• Higher Env Ab titers in Group 2 compared with Group 1
EnvA ELISA Responses – Group 3 (10
11vp)
No Response: samples #29 and #35
1.0 2.0 3.0 4.0 5.0 25 26 27 28 29 30 31 32 33 34 35 36 Log E nv A E LI S A Ti te r 0 2 4 6 8 24 26 28 52 week No Response No Response *
* samples not available
0 2 4 6 8 24 26 28 52 1.0 2.0 3.0 4.0 5.0 Week Log E nv A E LI S A Ti te r
EnvA ELISA Titer
Mean Median
Week 6: 4,406 10,000
Week 24: 759 1,000
Week 26: 12,525 30,000
Week 52: 2,411 3,000
• Comparable Env Ab titers in Group 3 compared with Group 2
EnvA ELISPOT Responses – Group 1 (10
9vp)
No Response: samples #1 and #12
EnvA SFC/106 PBMC Mean Median Week 6: 296 359 Week 24: 172 272 Week 26: 302 327 Week 52: 207 214 1.0 2.0 3.0 4.0 1 2 3 4 5 6 7 8 9 10 11 12 Log S FC / 1 0 ^ 6 P B M C 0 2 4 6 8 24 26 28 52 No Response No Response week 0 2 4 6 8 24 26 28 52 1.0 2.0 3.0 4.0 Week Log S FC / 1 0 ^ 6 P B M C
• Consistent Env T cell responses following week 0 and week 4 prime
EnvA ELISPOT Responses – Group 2 (10
10vp)
No Response: samples #14 and #23
EnvA SFC/106 PBMC Mean Median Week 6: 90 97 Week 24: 91 151 Week 26: 147 112 Week 52: 104 145 1.0 2.0 3.0 4.0 13 14 15 16 17 18 19 20 21 22 23 24 Log S FC / 1 0 ^ 6 P B M C 0 2 4 6 8 24 26 28 52 No Response No Response *
* samples not available
week 0 2 4 6 8 24 26 28 52 1.0 2.0 3.0 4.0 Week Log S FC / 1 0 ^ 6 P B M C
• Comparable Env T cell responses in Group 2 compared with Group 1
EnvA ELISPOT Responses – Group 3 (10
11vp)
No Response: samples #29 and #35 * samples not available
EnvA SFC/106 PBMC Mean Median Week 6: 236 245 Week 24: 307 309 Week 26: 441 417 Week 52: 312 282 1.0 2.0 3.0 4.0 25 26 27 28 29 30 31 32 33 34 35 36 Log S FC / 1 0 ^ 6 P B M C 0 2 4 6 8 24 26 28 52 No Response No Response * week 0 2 4 6 8 24 26 28 52 1.0 2.0 3.0 4.0 Week Log S FC / 1 0 ^ 6 P B M C
• Comparable Env T cell responses in Group 3 compared with Group 1
• Group 4: 5x1010 vp dose, week 0, 24 regimen
• Group 5: 1x1010 vp dose, week 0, 24 regimen
• Aims:
– To “fine tune” Ad26 vector dose for future studies
– To compare 1 (week 0) vs 2 (week 0, 4) priming immunizations
– To assess EnvA-specific T lymphocyte functionality by ICS
Preliminary Comparison of EnvA ELISPOT Responses in
Group 3 (10
11vp; wk 0/4/24) vs Group 4 (5x10
10vp; wk 0/24)
EnvA SFC/106 PBMC
Mean Median
Week 6: 314 437
• Comparable EnvA ELISPOT responses following 1 vs 2 Ad26 primes
EnvA SFC/106 PBMC Mean Median Week 6: 236 245 Week 24: 307 309 Week 26: 441 417 Week 52: 312 282 0 2 4 6 8 24 26 28 52 1.0 2.0 3.0 4.0 Week Log S FC / 1 0 ^ 6 P B M C Group 3 Group 4 TBD 0 2 4 6 8 24 26 28 52 1.0 2.0 3.0 4.0 Week Log S FC / 1 0 ^ 6 P B M C
EnvA IFN-
γ
ICS Responses – Group 4
Total, Central, Effector Memory CD8+ and CD4+ T Cells
0 2 4 6 8 0.001 0.01 0.1 1 10 % CD8 T Ce ll s 0 2 4 6 8 0.001 0.01 0.1 1 10 % CD8 CM T Ce ll s 0 2 4 6 8 0.001 0.01 0.1 1 % CD4 T Ce ll s 0 2 4 6 8 0.001 0.01 0.1 1 % CD4 CM T Ce ll s 0 2 4 6 8 0.001 0.01 0.1 1 % CD4 E M T Ce ll s 0 2 4 6 8 0.001 0.01 0.1 1 10 % CD8 E M T Ce ll s
• Multiple T lymphocyte subpopulations elicited by Ad26.ENVA.01
Week
Effector Memory Central Memory
• Ad26.ENVA.01 is safe and immunogenic in humans at doses of 109, 1010, and 1011 vp
• Reactogenicity reduced with 5x1010 vp dose as compared with
1011 vp dose; supports future studies with 4x1010 vp dose
• Immunogenicity of 109 vp in humans unexpected based on lack
of immunogenicity of 109 vp in NHP studies, suggesting that Ad
vectors are optimal in their natural host species
• Durability of humoral and cellular immune responses >52 weeks
• Responses (humoral>cellular) increased by homologous vector boost immunizations
Ad26 is a promising HIV-1 vaccine vector for further clinical development
First-in-Human Evaluation of a Prototype
Ad26.ENVA.01 Vaccine Vector: Conclusions
Immunogenicity of Heterologous Ad35/Ad26 Regimens
in Rhesus Monkeys
0 2000 4000 6000 0 2 4 12141824 0 2 4 12141824 0 2 4 12141824 0 2 4 12141824Ad5 Ad5 Ad5HVR48
Ad26
Ad35 Ad26 Ad48 Ad26
SFC / 1 0^ 6 PBMC Env Pol Gag week
Prime at week 0; Boost at week 12
High-dose, homologous, IV SIVmac251 challenge studies currently in progress Low-dose, heterologous, IR SIVmac251 challenge studies currently in progress
The Ad26 mosaic vaccine yielded many more Gag, Pol, and Env (A) epitope-specific T lymphocyte responses as well as (B) numbers of epitope
response regions to PTE peptides than did the Ad26 M consensus, clade B + clade C, or optimal natural clade C vaccines
P = 1 x 10-11, Poisson regression
P = 2 x 10-7, Poisson regression
Expanded Breadth by
Mosaic Compared with
Consensus or Natural
Gag/Pol/Env Antigens
in Rhesus Monkeys
Mosaic Env Antigens Elicit Noninferior ELISA and NAb
Responses Compared with Consensus or Natural
Sequence Env Antigens
Barouch et al. Nat. Med. 2010; 16:319-323
The mosaic vaccine elicited comparable ELISA and Tier 1 C (MW965.26) NAb titers (P = NS) and increased Tier 1 B (SF162.LS) NAb titers compared with the M consensus and optimal natural C clade vaccine (P = 0.02)
Proposed Next-Generation HIV-1 Vaccine Candidate:
Heterologous Adenovirus Mosaic Vaccine
NIH IPCAVD U19 AI078526 Program
• We aim to develop a global HIV-1 vaccine candidate for clinical evaluation
Vectors that avoid high levels of vector-specific NAbs and can be combined into a heterologous prime-boost regimen
• Heterologous Ad35/Ad26 prime-boost regimen
Antigens that elicit both humoral and cellular immunity and that optimize immunologic coverage of global virus diversity
• 2-valent mosaic Gag/Pol/Env antigens
• Ad35 and Ad26 vectors expressing mosaic HIV-1 Gag/Pol/Env are currently being manufactured for clinical studies by Crucell
Clinical Development Timeline
• 2010 : Evaluation of prototype Ad35/Ad26 prime-boost vector regimens in US, East Africa, South Africa (IPCAVD004 / IAVIB003)
– Collaborators: IAVI, HVTN, NIAID, Ragon Institute
• 2011 : Evaluation of Ad35/Ad26 mosaic Gag/Pol/Env vaccine
– Collaborators: IAVI, HVTN, NIAID, Ragon Institute
• 2011 : Evaluation of Ad26/MVA mosaic Gag/Pol/Env vaccine
– Collaborators: MHRP (NIAID, US Army)
Acknowledgements
• Beth Israel Deaconess, Harvard Medical School
– Peter Abbink – Kara Brandariz – Annalena La Porte – Jinyan Liu – Lauren Peter – Faye Stephens – Raphael Dolin – Michael Seaman
• New England Primate Research Center – Angela Carville – Keith Mansfield • LANL – Bette Korber • Emory University – Wendy Tan – Rafi Ahmed • Crucell Holland BV – Jaap Goudsmit – Sandra Kik
– Maria Grazia Pau
– Jerry Sadoff
– Hanneke Schuitemaker
– Mo Weijtens
– Gerrit Jan Weverling
– Jort Vellinga • IAVI – Jim Ackland – Jo Cox – Pat Fast – Jill Gilmour – Tom Hassell – Wendy Komaroff – Wayne Koff – Dagna Laufer – Angela Lombardo – Eddy Sayeed – Devika Zachariah • HVTN – Larry Corey – Jim Kublin – Cecilia Morgan • MHRP – Jerome Kim – Mary Marovich – Nelson Michael – Merlin Robb • Ragon Institute of MGH, MIT, and Harvard
– Zaza Ndhlovu
– Bruce Walker
• CAVD, Bill & Melinda Gates Foundation
• DAIDS, NIAID, NIH
– Elizabeth Adams – Chris Butler – Massimo Cardinali – Woody Dubois – Alan Fix – Dale Lawrence
– Mary Ann Luzar
– Rebecca Sheets
– Edith Swann
– Michael Pensiero
• Brigham & Women’s, Harvard Medical School
– Lindsey Baden – Brian Engelson – Patrick Falahee – Jen Johnson – Jane Kleinjan – Kathleen Krause – Caesar Lopez – Jamie Minchelo – Lizanne Noble – Alka Patel – Robert Tucker – Teresa Votto – Stephen Walsh – Marissa Wilck – Daniel Worrall • Safety Monitoring Committee – Paul Goepfert – Michael Keefer – Peter Wright
