David W. ScottDepartment of Medicine

Uniformed Services University of the Health SciencesBethesda, MD, USA

10th Open Scientific EIP SymposiumImmunogenicity of Biopharmaceuticals

Lisbon, Portugal, February 26, 2019

Modulation of immunogenicity by engineered antigen-specific regulatory T cells:

Fighting fire with fireman or police CARs

Our lab has focused on developing novel approaches to induce specific unresponsiveness (“immune tolerance”) and applying these to modulate human diseases and prevent/reverse adverse immune responses.

One such approach is regulatory T-cell therapy, which has been proposed to treat autoimmune diseases, allergy and transplant rejection, as well as to suppress undesirable antibody responses to bio-therapeutics, such as FVIII.

Dealing with immunogenicity and

adverse responses

Clinical studies with expanded human regulatory T-cell therapy are already in progress. However, these are polyclonal T cells that include a diverse repertoire of relativities.

Caveats:

The frequency of relevant regulatory T cells (Tregs) may be quite low.

Expanded polyclonal Tregs (multiple specificities) may be non-specifically immunosuppressive.

Rationale and issues

• Enrich and expand Tregs with antigen/tetramer, etc.

Possible solution based on chimeric antigen receptor (CAR) therapy for cancer:

Engineer specificity into polyclonal Tregs via retroviral transduction of specific “receptors”, e.g.:

T-cell receptor (TCR) CAR (scFv) or Antigen (B-cell antibody receptor=BAR)

Approaches

Approach to transduce

expanded polyclonal Tregs

Transduced antigen-specific polyclonal Tregs

Engineering antigen-specificity into polyclonal T cells:

Four flavors

Antigen-

specific

B cell

BARSignaling domains

Treg

*BAR Treg

BAR

Antigen-

specific

B cell

Signaling domains

CD8

*BAR CD8CAR Treg

Treg

ScFv

?

CARSignaling domains

APC

Teff

TCR Treg

TCRCD3

CD4

Treg

Signaling domains

*B-cell antibody receptor=BAR

Engineering antigen-specificity into polyclonal T cells:

TCR V-regions

APC

Teff

TCR

CD3

CD4

Treg

Signaling domains

TCR Treg effects

Aihong (Allan) Yong ChanZhang Kim

FVIII in hemophilia A

MBP in multiple sclerosis

Multiple systems:

Hemophilia inhibitors (FVIII)

Autoimmunity, e.g., MS (MBP) or Type 1 diabetes

Allergy (OVA)

Future targets (ADA’s)

Systems and targets

Hemophilia

X-linked blood clotting disorder

FVIII mutations cause Hemophilia A*

FIX mutations cause Hemophilia B

“Tenase” complex

*Deletions, inversions, missense, stop codons

Hemophilia

X-linked blood clotting disorder

FVIII mutations cause Hemophilia A*

FIX mutations cause Hemophilia B

“Tenase” complex

*Deletions, inversions, missense, stop codons

What is standard treatment for bleeds?

The unwelcome response to a human protein, FVIII

Hemophilia A patients can mount an immune response

to FVIII depending, in part, on the nature of their

mutation

Because they lack FVIII, they did not develop immune

tolerance to therapeutic FVIII

Specific antibodies against FVIII inhibit clotting by binding to domains required its bio-activity (“inhibitors”)

A1 A2

1 372 740

NH 22 B A3 C1 C2 COOH

1649 1689 2019 2173

A3

Application in Hemophilia A

Immunology 101: The immune Response to FVIII

Antigen presenting cells

FVIII protein

FVIII peptide

Cytokines

Activated FVIII-specific B cells

Activated FVIII-specific T cells

FVIII-specific plasma cells

FVIII peptide

FVIII-specific TCR

FVIII-neutralizing

inhibitor antibody

FVIII protein

FVIII-specific helper T cell

FVIII-specific regulatory T cell

aka “Police CARs”

Treg

(CD4+CD25hiCD127l)

T naive (helper)

(CD4+CD25-CD45RA+)

►FSC

►S

SC

►CD4►

CD

25

►CD127

►C

D2

5

►CD4

►C

D4

5R

A

►C

D2

5

►CD127

►CD127 ►CD4

►C

D2

5

►C

D4

5R

A

►Helios

►F

oxp

3

►Helios

►F

oxp

3

Tnaive

Treg

Isolation of naive T cells and regulatory T cells

from normal donor PBMC

Induction of Foxp3 and GARP

Mock

17195

Fo

xp

3

GARP

OVA

peptide

FVIII

peptide Anti-CD3e

GITRLAP

GF

P+

Mo

ck

GF

P+

17195

No antigen

pC2 (2191-2210)

Induction of LAP and GITR

Antigen-specific upregulation of Treg markers in 17195 Tregs

FVIII-C2-specific immunosuppression by Treg17195

Teff : Treg ratio

0.5 1 2 4 8 No Treg

Teff/Treg ratioYC Kim et al. Blood 125: 1107, 2015.

Can this approach work to prevent or reverse inhibitor responses in

hemophilia A mice ?

Protocol of FVIII-specific suppression of secondary antibody formation by

engineered FVIII-specific human Tregs

n wks

No FVIII + FVIII

7 d

ays

HLA.DR1XE16

Immunization in vivo Reactivation in vitro

rFVIII

ELIspot assay to detect anti-FVIII antibody

spleen

FVIII

Immunized mice

17195* Mock

TregsNo FVIII + FVIII

0

1/2

1/4

1/8

1/16

Tregs

SHOW FIGURE QUANTITATION

*TCR vs. C2 domain peptide

Kim YC et al. Blood 125: 1107, 2015.

Engineering antigen-specificity into polyclonal T cells:

Single chain (scFv) CARs

APC

Teff

TCR Treg

TCRCD3

CD4

Treg

Signaling domains

CAR Treg

Treg

ScFv

?

CARSignaling domains

CAR Treg

?

CARScFv vs. antigen

Treg

Signaling domains

What about CAR (chimeric single chain Fv) Tregs?

Antigen on B cell or APC or endothelial cell surface

Both TCR- or scFv engineered human Tregs suppress the

secondary anti-FVIII response in vitro

scFv TCR(A2) (C2)

Yoon et al., Blood, 129: 238-245, 2017.

Jeongheon Yoon

Anja N. Schmidt

TCR- or scFv engineered human Tregs suppress the anti-FVIII response

in vivo

MockTCR vs. C2scFv vs. A2

Scheme for bystander suppression of multiple

T-cell clones by a single Treg

17195 TCR

A2

C1

C2

T effector

Treg

APC

?

?

?

xxx

Question:

Can antigen-expressing “BAR” T-cell

therapy modulate antibody responses by

directly engaging antigen-specific B cells?

“BAR” = B-cell antibody receptor

FVIII-specific B cell

BAR (B-cell Antibody Receptor) Treg

FVIII-specific

BAR Treg/CD8

Structure of BAR

(B-cell Antibody Receptor)

Treg or CD8 cell

FVIII domain

KalpanaParvathaneni

Engineering antigen-specificity into polyclonal T cells:

Targeting the B cell

APC

Teff

TCR Treg CAR Treg

Treg

ScFvTCRCD3

CD4

?

Treg

CARSignaling domains

Signaling domainsBAR

FVIII-

specific

B cell

Signaling domains

Treg

BAR Treg

FVIII-

specific

B cell

BARSignaling domains

CD8

BAR CD8

A2/C2 BAR mCD8-mediated elimination of anti-FVIII B cells from E16-mouse spleen cells stimulated with LPS

OVA BARNo CD8No LPS

LPS (1 μg/mL) E/T ratio: 5:1

A. αFVIII IgM+ ELISPOT assay by LPS-stimulated E16 B cells B. Quantification of number of spots

no CD8s A2 /C2 BAR OVA BAR no LPS0

500

1000

1500

2000

2500

Naive B cells + LPS 1mg/mL

# o

f S

po

ts p

er

1xE

6 C

ells

BAR-CD8 mediated Elimination of a FVIII IgM+ B Cells

A2/ C2 BAR

FVIII-coated wells

A2 BARControl 2 3 4 5

Day 18

Day 25

Day 10

OVA BARControl 2 3 4 5

Survival of 2JLO-injected NSG mice with BAR CD8 T-cell therapy

CD8

FVIII-

specific

B cell

BAR CD8

Can “BAR” engineered CD4 Tregs target and suppress FVIII-

specific B cells

Treg

FVIII-

specific

B cell

BAR Treg

FVIII

domain

Prevention of anti-FVIII antibody development in naïve E16 mice by BAR human Tregs in vivo

An

ti-F

VII

I a

nti

bo

dy

(µ

g/m

l)

1 4 2 1 2 8 3 5 4 2 4 9 5 6 6 3 7 0

0

5

1 0

1 0 0

2 0 0

3 0 0 O b 2 F 3 h T re g s

F V III B A R h T re g s

Multiple systems:

Hemophilia inhibitors (FVIII)

Autoimmunity, e.g., MS (MBP) or Type 1 diabetes

Allergy (OVA)

Future targets (ADA’s)

Systems and targets

BAR (B-cell Antibody Receptor) TregCan BAR Tregs be used to modulate allergy?

Mast cell with FceROVA-specific B

cell

Allergic response

Isolated

T cells

Viral

systems

Generic donor

Suppression of specific

T and B cells

Virally

Transduced T

cells

Engineered T

cells

Future: CAR or BAR cell therapy not only for hemophilia, but

also for allergy, transplantation, autoimmunity or other

monogenic diseases (and ADA?)

• Antigen-specific TCRs, single chain Fvs and antigen domains (BARs)

have now been engineered for retroviral transduction into human T

effectors and human (mouse) Tregs.

• These Tregs specifically suppressed both proliferation and cytokine

production by antigen-specific T effectors, and antibody formation in vitro

and in vivo in multiple model systems.

• Recent data with “BAR” CD8’s and Tregs (expressing antigen domains)

may allow multiple approaches to regulate adverse immune responses.

e.g., Ovalbumin-BAR iTregs are able to suppress both active and

passive anaphylaxis.

• Expansion of these studies to Tregs in a larger species (hemophilic

dogs) is in progress, with human clinical studies on the horizon.

Summary

Acknowledgements

Yongchan Kim Jeongheon Yoon

KalpanaParvathaneni

MahaAbdeladhim

Allan Zhang

Edward Mitre Laura Kropp

USUHS USUHS

Anja Schmidt

Frankfurt

Chris KönigsFrankfurt

Ethan ShevachNIH

Kate PrattUSUHS

Kai Wucherpfennig

Harvard

Supported by NIH/NHLBI grants RO1 HL126727 and R21 HL127495and NMSS RG1606-24524

ObrigadoGracias