OPAL immunotherapy for HIV

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OPAL immunotherapy for HIV

• Stephen Kent
• University of Melbourne

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Immune Control of HIV

• The immune system helps partially control HIV
• After initial infection, a 99 reduction in virus
  occurs
• Most scenarios of HIV control linked to T cell
  immunity
• Whats the best way to measure effective T cells?
• In vivo clearance of infected cells?
• Can natural control of HIV be mimicked by a
  vaccine immunotherapy?

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In vivo killing assay
Are the Gag-dyed cells being eliminated?
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Overlapping peptides spanning whole virus proteins
Protein amino acid sequence (e.g. HIV Gag)
IEEKKFGAEVVPGFQALSEGCTPYDINQMLNCVGDHQAAMQIIRDIINE
EAADWDLQHPQPAPQQGQLREPSGSDIAGTTSSVDEQIQWMY
IEEKKFGAEVVPGFQ

KFGAEVVPGFQALSE

EVVPGFQALSEGCTP


GFQALSEGCTPYD
LSEGCTPYDINQMLN

CTPYDINQMLNCVGD
DINQMLNCVGDHQAA

MLNCVGDHQAAMQII


VGDHQAAMQIIRDII

QAAMQIIRDIINEEA


QIIRDIINEEAADWD

DIINEEAADWDLQHP


EEAADWDLQHPQPAP


DWDLQHPQPAPQQGQ


QHPQPAPQQGQLREP


PAPQQGQLREPSGSD



QGQLREPSGSDIAGT


REPSGSDIAGTTSSV



GSDIAGTTSSVDEQI



AGTTSSVDEQIQWMY

• Overlapping peptides
• 15 amino acids long
• Overlapping by 11 amino acids

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Killing of Gag and Pol labeled cells in immune
animals early after SHIV infection
Control 1.0
Pol 1.0
Gag 1.0
Unimmunized monkey
SNARF
CFSE
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Implications of the in vivo killing data.

• If the blood cells labelled with the overlapping
  HIV peptides are being recognised and killer by
  the T cells of the immune system..might they
  also stimulate and expand the T cells? (i.e. act
  like a vaccine)

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IMMUNOGENIC?
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Boost in T-cell responses analysed by Elispot
GAG
POL
GAG
POL
Pre- Peptide- pulsed cell infusion
1 week later
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Boost in responses to whole inactivated SIV
IFNg spot forming cells per 106
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Boost in both CD4 and CD8 responses by ICS
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OPAL immunotherapyEnhancing cellular immunity
by the infusion of Overlapping Peptide-pulsed
Autologous celLs
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• Does whole blood work instead of isolating PBMC?
• Pulsing whole blood is more practical
• Less time-consuming

Gag pool
Pol pool etc
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Can responses be boosted against almost all SHIV
proteins?

• Macaques chronically infected with SHIVmn229
• Infused with 3 monthly doses fresh autologous
  blood pulsed with Gag, Pol, Env, Tat, Rev, Nef,
  Vpu (gt87 of virus).

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Can span nearly the whole proteome?Boosting of
broad SHIV-specific T cell responses by 3
infusions of peptide pulsed blood
CD4 responses CD8 responses
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Conclusions

• Pulsing whole blood with overlapping peptides is
  highly T-cell immunogenic
• Peptide dose used 5µg/mL
• Advantages
• Simple
• Large breadth of immunity
• Boosts pre-primed responses
• Can induce new responses
• CD4 and CD8
• Dont need to know MHC type
• Dont need to know epitopes
• No antigen presentation machinery required
• No manipulation/selection of APCs

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Safety in macaques

• Only peptides and autologous cells/blood
• No organ toxicity/deaths
• No reductions in activity or food intake
• No remarkable findings on physical examinations
  at times of blood sampling
• No weight loss attributable to procedure
• No unexpected blood test abnormalities
• Toxicology study of peptides made under GMP-like
  conditions underway

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Limitation high VL and low total CD4 T cells
()
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Can OPAL reduce VL?

• Monkey studies so far underpowered to detect
  differences
• Compounded by variable immunodeficiency
• Large study of 36 ARV-treated animals underway

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Anecdote Control of viremia in OPAL boosted
animal
But Recrudesence of viremia after CD8 depletion!
copies per mL)
SHIV Viral load
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(Log
Week post SHIVMN229 Infection
Day post CD8 T cell depletion
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Controlled again .. by massive SHIV-specific CD4
and CD8 T cell response
copies per mL)
SHIV Viral load
10
(Log
Week post SHIVMN229 Challenge
Day post CD8 T cell depletion
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Summary

• Interesting discovery
• Immunogenic
• Advanced development through non-human primates
• No mouse model!
• Safe
• Can it reduce virus levels?
• Will it work in people?

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Many thanks

• Socheata Chea, Jane Dale, Rob De Rose
• Liyen Loh, Viv Peut, Vinca Alcantara, Bridget
  Pratt, Miranda Smith, Erik Rollman, Caroline
  Fernandez, Rosie Mason, Kim Szalnowski
• Amanda Handley, Mark Sullivan, Jim Ackland OPAL
  Therapeutics