t-cell hiv vaccines giuseppe pantaleo, m.d. professor of medicine director, swiss vaccine research...

T-cell HIV Vaccines

Giuseppe Pantaleo, M.D.Professor of MedicineDirector, Swiss Vaccine Research InstituteLausanne, Switzerland

Challenges In The Development Of An HIV Vaccine

Identification of immune correlates of protection

Induction of a broad neutralizing antibody response

Induction of effective T cell responses

Viral diversity

Viral escape

Super-infection

Influence of genetic background

Induction of mucosal and systemic immunity

Complexity of immunization regimens

Vaccine Concepts and Designs

Live Vectors DNA Combination of Elements Peptide Epitopes (limited immunogenicity) Pseudovirions (pre-clinical) Live-Attenuated (Not Under Study in

Humans) Whole-Killed (Not Under Study in Humans) Recombinant Viral Proteins

Due to the Lack of Protein-Based Env

Vaccines Able To Induce Neutralizing

Antibodies, Candidate HIV Vaccines Have

Been Designed Primarily to Induce T-Cell

Immune Responses

T-cell Vaccines Do Not Prevent Infection

But They Will Be Eventually Associated

with Control of Virus Replication and

Prevention of HIV-Associated Disease

T-cell HIV Vaccines Concept

T-Cell HIV Vaccine Concept

Help CTL

Vaccine

----Virus

Placebo

Virus

exposure

Rationale for the Effectiveness of HIV

T-Cell Vaccines

- Certain experimental vaccines confer protection in monkeys infected

with SIV

- There is evidence that HIV-1-specific T-cell responses may confer

protection (e.g. exposed non-infected subjects)

- A small percentage (<5%) of HIV-1-infected subjects show no signs of

disease progression (e.g. long-term nonprogressors)

- A decrease in viral load is associated with clinical benefit

Low responder High responder

Effective immunity induced by rAd5 HIV (SIV) vaccine in a SIV challenge model

Interpretation This cell-mediated immunity vaccine did not prevent HIV-1 infection or reduce early viral level.

Mechanisms for insufficient efficacy of the vaccine and the increased HIV-1 infection rates in subgroups of vaccine

recipients are being explored.

Vol. 307 November 29, 2008

Vol. 307 November 29, 2008

Interpretation Consistent with previous trials, the MRKAd5 HIV-1 gag/pol/nefvaccine was highly immunogenic for inducing HIV-

specific CD8+ T cells. Our findings suggest that future candidate vaccines have to elicit responses that either exceed in magnitude or

differ in breadth or function from those recorded in this trial.

Messages from the Step Study

The Step study marks the end of the HIV T-cell vaccine concept (at least of the Ad5 vector used alone)

It draws the attention on the potential danger of pre-existing immunity

It shows a potential sinergy between Ad5 pre-existing immunity and circumcision with regard to the observed increased in HIV acquisition

It indicates that the magnitude and the quality (breadth) of the vaccine-induced T-cell responses (particularly CD8 T-cell responses) are not optimal

CONCLUSIONS

This ALVAC-HIV and AIDSVAX B/E vaccine regimen may reduce the risk of HIV infection in a

community-based population with largely heterosexual risk. Vaccination did not affect the viral load or

CD4+ count in subjects with HIV infection. Although the results show only a modest benefit, they offer

insight for future research. (ClinicalTrials.gov number, NCT00223080.)

Major Messages from the RV-144 Study

The vaccine combination is potentially more effective (61% reduction of HIV acquisition at 1 year post vaccination)

The vaccine protective effect is waning over time (31.2% at 3 years post-vaccination)

The delta in the reduction of the number of infections is 18 (30 in the placebo vs. 12 in the vaccine group) at 1 year and 23 (74 in the placebo vs. 51 in the vaccine group) at 3 years

Therefore, most of the protective effect is gained during the 1st year post-vaccination

RV-144 Results and Immunological Issues

The limited set of immunological results of the RV-144 trial do not allow to rule out or to favor any specific cellular or humoral mechanism of protection.

In this regard:• The same protein component of the vaccine combination was not

associated to protection when used alone in the Vaxgen phase III trial. However, due to differences in the target population, i.e. high risk IVDU population in the Vaxgen trial versus low risk in the RV-144 trial, the two studies cannot be compared.

• The poxvirus component of the vaccine, i.e. ALVAC, was never previously tested in phase III trial.

RV-144 Results and Immunological Issues

The results of the RV-144 trial re-underscore a number of immunological issues that have been repetitively raised in the recent past but have never been concretely addressed. These include:• the need of developing an integrated vaccine-induced immune

response (innate plus humoral plus adaptive)• the exploration of additional mechanisms of protection beyond

the conventional CD4 and cytotoxic CD8 T-cell and neutralizing antibody responses

What Is Next?

Improvement of the Current Vaccine Combination

Augment (above the 61% efficacy observed at 1 year post-infection) the overall protection from infection

Induce durable protection Improve both components of the vaccine, i.e. the

priming component (ALVAC) and the boosting component (the Env protein)

20

What Is Next?

Vaccine candidates Poxvirus-based vectors

- NYVAC- MVA- ALVAC

Adenovirus- Ad26- Ad35

DNA vectors Protein

- gp140 monomer or trimer

November 15, 2008, Vol. 198

DNA-C + NYVAC-C PlatformHarari et al. JEM, 2008; Bart et al., Vaccine, 2008; McCormack, Vaccine, 2008

Supported by the European Union, EuroVacc, ANRS and CAVD

TVDCPoxvirus T Cell Vaccine Discovery

Consortium

Clinical Trial Design

Randomized trial with a parallel group design

Open to the participants and investigators but blind to laboratory personnel

Attendance to clinics at least 14 occasions over 72 weeks

0 4 8 20 24 28 48 72Weeks

Group 1 (n=74)

Group 2 (n=73)

DNA-C (4 mg) priming at week 0, 4 and 8 for group 1 at week 0 and 4 for group 2

NYVAC-C (107.5

PFUs) boosting at week 24 for group 1 and at week 20 and 24 for group 2


Consortium

Proportion of Responders at Primary Endpoints (Week 26/28)

ITT Analysis 3 x DNAn = 70

2 x DNAn = 70

Total n = 140

Response 64 (91%) 56 (80%) 120 (86%)

PP Analysis 3 x DNAn = 67

2 x DNAn = 68

Total n = 135

Response 63 (94%) 55 (81%) 118 (87%)

Chi2 Test: p = 0.053; Risk difference: 11.4% (95% CI 0.0 – 22.9%)



Consortium

Proportion of Responders Over Time


Consortium

Magnitude of IFN-g ELISpot Responses at Week 26/28 Overall (SFUs/106 cells)

Week 26 Week 28

ITT Analysis3 x DNA

n=582 x DNA

n=503 x DNA

n=612 x DNA

n=54

Mean (SD)Median

(IQR;range)

774 (622) 545

(340-1101;75-3454)

398 (318) 328

(178-488;63-1514)

597 (519) 445

(170-855; 88-2773)

357 (319) 235

(123-505;60-1326)

Mann-Whitney test

p<0.001 p<0.001

Note: Sum of SFU/Mio cells from all peptide pools with a positive response per participant


Consortium30

Magnitude of IFN-g ELISpot Responses at Week 26/28 (ITT)

0

200

400

600

800

1000

1200

1400

1600

1800

2000

2200

ENV Other ENV Other ENV Other ENV Other

3 x DNA 2 x DNA

SFUs/Mio cells

Week 28Week 26Week 28Week 26

Note: Magnitude statistically different between groups for Env at both weeks but not for

Gag/Pol/Nef (Other)


Consortium

Functional Profile of HIV-Specific T-Cell Responses

Neg

Env 1

Env 2

Subject#1042

Gr#1

0 10

2

10

3

10

4

10

5

<APC-A>

0

10

2

10

3

10

4

10

5

0.033 2.99e-3

1.2e-31000 10

2

10

3

10

4

10

5

<APC-A>

0

10

2

10

3

10

4

10

5

0.013 2.39e-3

1.79e-3100

0 10

2

10

3

10

4

10

5

0

10

2

10

3

10

4

10

5

0.05 0.019

1.65e-399.90 10

2

10

3

10

4

10

5

0

10

2

10

3

10

4

10

5

0.031 0.017

3.71e-399.9

0 10

2

10

3

10

4

10

5

0

10

2

10

3

10

4

10

5

0.069 0.13

7.13e-399.8

0 10

2

10

3

10

4

10

5

0

10

2

10

3

10

4

10

5

0.04 0.11

0.03299.8

IL-2

IFN-

TN

F-α

CD4 T-cell responses

0 10

2

10

3

10

4

10

5

0

10

2

10

3

10

4

10

5

0.036 0.013

0100

0 10

2

10

3

10

4

10

5

0

10

2

10

3

10

4

10

5

8.5e-3 0

8.5e-3100

0 10

2

10

3

10

4

10

5

0

10

2

10

3

10

4

10

5

0.093 0.22

4.18e-399.7

0 10

2

10

3

10

4

10

5

0

10

2

10

3

10

4

10

5

0.019 0.077

0.1299.8

0 10

2

10

3

10

4

10

5

0

10

2

10

3

10

4

10

5

0.067 0.027

3.54e-399.9

0 10

2

10

3

10

4

10

5

0

10

2

10

3

10

4

10

5

0.016 2.66e-3

0.017100IL

-2 TN

F-α

IFN-

CD8 T-cell responses


Consortium

Group = Gr1 Group = Gr2

0

0.1

0.2

0.3

0.4

IFNgIL-2

TNFa(Pies)(Bar#)

+++

++-

+-+

+--

-++

5

-+-

--+

---

Excluded values: stimulation = SEB; stimulation = NEGAveraged over: patients ID; stimulationThreshold = 0

Group = Gr1Group = Gr2


0

0.1

0.2

0.3

0.4

IFNgIL-2

TNFa(Pies)(Bar#)

+++

++-

+-+

+--

-++

5

-+-

--+

---



0

0.1

0.2

0.3

0.4

IFNg

IL-2

TNFa

+

+

+

+

+

-

+

-

+

+

-

-

-

+

+

-

+

-

-

-

+


0

0.1

0.2

0.3

0.4

IFNgIL-2

TNFa(Pies)(Bar#)

+++

++-

+-+

+--

-++

5

-+-

--+

---




0

0.1

0.2

0.3

0.4

IFNgIL-2

TNFa(Pies)(Bar#)

+++

++-

+-+

+--

-++

5

-+-

--+

---



0

0.1

0.2

0.3

0.4

IFNg

IL-2

TNFa

+

+

+

+

+

-

+

-

+

+

-

-

-

+

+

-

+

-

-

-

+

Gr#1

Gr#2

Gr#1

Gr#2

Gr#1 Gr#2 Gr#1 Gr#2

Fre

qu

en

cy o

f C

D4

T-ce

lls

Fre

qu

en

cy o

f C

D8

T-ce

lls

CD4 T-cell responses CD8 T-cell responses

Functional Profile of HIV-Specific T-Cell Responses


Consortium

Number of Pools Recognized

P=0.02

0

2

4

6

8

Nu

mb

er

of

resp

on

ses

pe

r su

bje

ct

CD4 T c

ells

CD8 T c

ells

CD4 T c

ells

CD8 T c

ells

Gr1

N=14

Gr2

N=11

Median


Consortium

Distribution of HIV Regions Targeted By CD4 T-Cell Responses

ENV n o n -EN V

0

5

10

15

20

25

30

Gr#1

N=44 responses

Gr#2

N=28 responses

GAG

POL

NEF

ENV

Nu

mb

er

of

res

po

ns

es

ENV Gag, Pol or Nef

P=0.06

Gr#1

Gr#2


Consortium

Distribution of HIV Regions Targeted By CD8 T-Cell Responses

ENV n o n -EN V

0

2

4

6

8

10

12

14

Gr#1

N=22 responses

Gr#2

N=8 responses

Nu

mb

er

of

res

po

ns

es

ENV Gag, Pol or Nef

P=0.01

GAG

POL

NEF

ENV

Gr#1

Gr#2


Consortium

Total Magnitude of T-Cell Responses (Sum of Responding Pools)

CD4 T c

ells

CD8 T c

ells

CD4 T c

ells

CD8 T c

ells

0.0

0.5

1.0

1.5

2.0

Per

cen

tag

e o

f T-

cells

Gr1

N=14

Gr2

N=11


Consortium

EV03/ANRS VAC20: NYVAC- and HIV-Specific CD4 and CD8 T-Cell Responses in the Gut

0 10 2 10 3 10 4 10 5

0

10 3

10 4

10 5

0.87

0 10 2 10 3 10 4 10 5

0

10 3

10 4

10 5

11.9

0 10 2 10 3 10 4 10 5

0

10 3

10 4

10 5

6.42

0 10 2 10 3 10 4 10 5

0

10 3

10 4

10 5

0.52

0 10 2 10 3 10 4 10 5

0

10 3

10 4

10 5

10.1

0 10 2 10 3 10 4 10 5

0

10 3

10 4

10 5

1.13

unstimulated NYVAC HIV

Blood

Gut

Gated on CD3+CD4+

CFSE

CD

4

0 10 2 10 3 10 4 10 5

0

10 3

10 4

10 5

0.34

0 10 2 10 3 10 4 10 5

0

10 3

10 4

10 5

24

0 10 2 10 3 10 4 10 5

0

10 3

10 4

10 5

10.6

0 10 2 10 3 10 4 10 5

0

10 3

10 4

10 5

0.5

0 10 2 10 3 10 4 10 5

0

10 3

10 4

10 5

4.85

0 10 2 10 3 10 4 10 5

0

10 3

10 4

10 5

0.57

Gated on CD3+CD8+

unstimulated NYVAC HIV

Blood

Gut

CFSE

CD

8

38

What Is Next?

Potential vaccine commbinations (with novel env protein

candidates) Poxvirus-based vaccine combinations

- NYVAC (2X or 4X) plus gp120/140 (2X or multiple)- DNA (3X) plus NYVAC (1X) plus gp120/140 (2X or multiple)- ALVAC (4X) plus gp120/140 (2X or multiple)

Adenovirus-based vaccine combinations- Ad26 (1X) plus Ad35 (1X) plus gp120/140 (2X or multiple)- Ad26 (2X) plus MVA (1X) plus gp120/140 (2X or multiple)

TVDC

Current and Future Poxvirus Vectors Portfolio

571 passages

In CEF cells

Deletion of 18

ORFs

200 passages

in CEF cells

Vaccinia Virus

Ankara (MVA)

Vaccinia Virus

Copenhagen

Canarypox

virus

MVA NYVACALVAC

Gene deletion

Combined NYVAC

Rc Plus

Gene deletion

NYVAC

Attenuated

Rc NYVAC KC

Reinsertion of

K1L & C7L

Gene deletion

mutants

40

Conclusions

T-cell vaccines remain an important component of the overall HIV vaccine strategy

They serve as the priming component in combination regimens with env proteins

It is conceivable that improved T-cell vaccines may substantially impact the magnitude, quality and durability of the antibody response induced by env protein vaccines

The Step and RV-144 efficacy trials have indicated that the current NHPs challenge model is not suitable for the prediction of the clinical efficacy of vaccine candidates in humans

The evaluation of improved vaccine combinations in efficacy clinical trials is the only strategy for the correct evaluation of the vaccine effectiveness

AcknowledgementsVaccine Immunotherapy CentreDiv. of Immunology and Allergy CHUV – Lausanne, Switzerland Pierre-Alexandre Bart Erika Castro David Bonnet

Kim Ellefsen-Lavoie Alexandre Harari

St. Mary Hospital,Imperial College London, UK Jonathan Weber Rebecca Chandler Lucy Garvey Ken Legg Ngaire Latch

University of Regensburg, Germany Bernd Salzberger Ralf Wagner Hans Wolf Birgit Fritsch Falitsa Mandraka Gabriele Birkenfeld Caspar Franzen Josef Köstler

ANRS Jean-Francois

Delfraissy Yves Levy Anne de Saunière Véronique Rieux

EuroVacc Foundation Song Ding

Sanofi Pasteur, France Jim Tartaglia Claude Meric

Collaboration for AIDSVaccine Discovery (CAVD) Nina Russell Jose Esparza

European Commission

EuroVacc Foundation

ANRS

CAVD

&

All Study Volunteers

Cochin, Paris, France

Odile Launay

Pierre Loulergue

Yvette Henin

Henri Mondor, Paris,

France

Yves Lévy

Jean-Daniel Lelièvre

Christine Lacabaratz

Tenon, France

Gilles Pialoux

Marseille, France

Isabelle Poizot-Martin

Catherine Farnarier

Toulouse, France

Lise Cuzin

Florence Nicot

INSERM CTU U897, France

Genevieve Chene

Philippe Reboud

Inga Tschöpe

Carine Grondin

Valérie Boilet

MRC CTU, London, UK

Sheena McCormack

Abdel Babiker

Wolfgang Stöhr

Liz Brodnicki

Patrick Kelleher

Mary Rauchenberger

Shabana Khan


Consortium

Proportion of Responders at Week 26/28 per Peptide Group

ITT Analysis 3 x DNAn = 70

2 x DNAn = 70

Total n = 140

Env 63/70 (90%) 54/69 (78%) 117/139 (84%)

Gag/Pol/Nef 27/70 (39%) 17/70 (24%) 44/140 (31%)


2 x DNAn = 68

Total n = 135

Env 62/67 (93%) 53/67 (79%) 115/134 (86%)

Gag/Pol/Nef 26/67 (39%) 17/68 (25%) 43/135 (32%)


Consortium

Primary Immunogenicity Endpoints ITT Analysis 3 x DNA

n = 702 x DNAn = 69

Total n = 139

Response 26 (37%) 15 (22%) 41 (30%)


2 x DNAn = 67

Total n = 134

Response 25 (37%) 15 (22%) 40 (30%)


Risk atio: 1.7 (95% CI 1.0 – 2.9)

Chi2 Test: p = 0.059; Risk difference: 14.9% (95% CI -0.3 – 30.2%)

Risk ratio: 1.7 (95% CI 1.0 – 2.9)


Consortium

Magnitude of IFN-g ELISpot Responses at Week 26/28 by Peptide Group (median (IQR) SFUs/106 cells)

Week 26 Week 28

ITT analysis3 x DNA

n=212 x DNA

n=133 x DNA

n=212 x DNA

n=13

Gag/Pol/Nef180 (120-331) 109 (85-174) 145 (83-229) 113 (83-218)

p=0.12 P=0.82

Week 26 Week 28

ITT analysis3 x DNA

n=582 x DNA

n=483 x DNA

n=592 x DNA

n=54

Env 539 (315-1013) 294 (182-496) 442 (170-833) 217 (123-488)

p<0.001 p=0.003

Challenges in HIV Vaccine Development

30 commercially available effective vaccines 16 vaccine derived from live replcation

competent attenuated pathogens 12 vaccine derived from pathogen

modifications Only 2 vaccines, HPV and HBV derived from

synthetic products

t-cell hiv vaccines giuseppe pantaleo, m.d. professor of medicine director, swiss vaccine research...

Documents

candidate hiv vaccines

specific tcell responses

prevention of hiv

based env vaccines able

neutralizing antibodies

control of virus replication

exposed noninfected

lack of protein