RESEARCH POSTER PRESENTATION DESIGN © 2015

www.PosterPresentations.com

• AB154 is a humanized monoclonal antibody that potently inhibits the interaction of TIGIT

and CD155 with sub-nanomolar affinity.

• TIGIT, PD-1, and CD226 expression are correlated in many tumor types and are often co-

expressed on tumor infiltrating lymphocytes (TILs). CD155 is also presented by cancer

types of interest.

• Positive viral status is associated with higher levels of TIGIT, PD-1, and CD226 in head and

neck tumors. CD155 expression is negatively correlated with HPV+ status.

• CD8+ T cells make up the majority of antigen-experienced T cells in advanced head and

neck tumors. Antigen experience occurs alongside markers of immune exhaustion and loss

of CD226 expression.

• AB154-dosed patients had complete receptor coverage on all TIGIT-expressing peripheral

leukocytes in the first cohort of a Phase 1 trial (NCT03628677).

Anderson AE, DiRenzo D, Lee S, Udyavar A, Gerrick K, Singh H, Zhang K, Zhao X, Jin L, Seitz L, Walker NPC, Walters MJ, Tan JBL

Arcus Biosciences, Inc.; 3928 Point Eden Way, Hayward, CA 94545 (USA)

Characterization of AB154, a Humanized Anti-TIGIT Antibody,

For Use in Combination Therapies

AB154 is a humanized antibody that blocks human TIGIT (T-cell immunoreceptor with Ig and

ITIM domains), an inhibitory receptor expressed on natural killer (NK) cells, CD8+ T cells,

CD4+ T cells and regulatory T cells (Treg). CD226 (or DNAX Accessory Molecule-1, DNAM-1)

is an activating receptor that competes with TIGIT for shared ligands CD155 (PVR) and

CD112 (Nectin-2), expressed by cancer and antigen-presenting cells. TIGIT blockade by

AB154 prevents binding to its ligands and shifts the immune balance towards a more

favorable CD226 interaction. AB154 has the potential to promote sustained immune

activation and tumor clearance, particularly in combination with other immunotherapies such

as AB122 (anti-PD1).

In Vitro Assays: AB154 binding affinity was determined in CHO cells over-expressing

human TIGIT. Inhibition of CD155 interaction was quantified using a TIGIT-expressing

reporter gene cell line.

Gene Expression: Expression of TIGIT, PD-1 (PDCD1), CD226, PD-L1 (CD274), and

CD155 (PVR) on select tumor types were derived from RNASeq in The Cancer Genome

Atlas (TCGA) database and displayed as log2 transformed expression of counts per million.

Flow Cytometry on Human Head & Neck Tumors: Dissociated tumor samples were

purchased from Discovery Life Sciences (n = 5). Cells were stained with LIVE/DEAD Fixable

Aqua (ThermoFisher), then stained for surface markers or isotype controls related to T cell

lineage, exhaustion, and activation. Cells were fixed and permeabilized, washed and stained

for intracellular markers prior to data collection.

Immunohistochemistry (IHC): Anti-CD155 antibody (Cell Signaling Technology, D8A5G)

was used to stain FFPE human tissues. Samples were deparaffinized according to standard

methods and heat-induced epitope retrieval was performed using sodium citrate. Anti-rabbit

HRP and DAB chromogen were used for detection.

Clinical / PD: A Phase 1 dose-escalation study is underway to evaluate AB154 as a

monotherapy and in combination with AB122 (anti-PD1) in participants with advanced solid

malignancies. Whole blood was obtained from patients at the first dose level (n = 3) and

receptor occupancy (RO) was determined by flow cytometry using saturating levels of a

competing anti-TIGIT antibody.

Introduction

Figure 1. TIGIT binds to CD155 and results in decreased activation of the TIGIT-

expressing immune cells. AB154 blockade of TIGIT allows CD155 to bind CD226, favoring T

cell and NK cell activation.

TIGIT, PD-1, and CD226 Are Co-Expressed on Human Tumors

Results

Materials and Methods

Conclusions

Interested in a career at Arcus? Visit www.arcusbio.com

AACR 2019

National Meeting; Atlanta

Abstract #1557

T cell and NK

cell Activation

CD155

TIGIT

CD226

(DNAM-1)

T cell and NK

cell Activation

CD155

TIGIT

CD226

(DNAM-1)AB154

Antigen Experienced CD8+ T Cells Isolated from Advanced

Head and Neck Tumors Express Higher TIGIT and PD-1

CD155 Stains Strongly in Cancer Types of Interest

NSCLC HNSCC CervicalTNBC

Figure 5. CD155 immunohistochemistry (IHC) shows membrane and cytoplasmic

localization on cancerous cells in non-small cell lung cancer (NSCLC), head and neck

squamous cell carcinoma (HNSCC), triple negative breast cancer (TNBC), and cervical

carcinoma. Arrows indicate areas of positive staining on tumor cells.

Figure 3. RNASeq data from TCGA reveals high levels of TIGIT and PD-1 (PDCD1) co-

expression across many tumor types. CD226 is often expressed in TIGIThi PD-1hi tumor

types; however, CD155 (PVR) is not strongly correlated with these immune markers.

Positive viral status in HNSCC is associated with higher levels of TIGIT, CD226, and PD-1.

CD155 is negatively correlated with viral status, while PD-L1 (CD274) has no significant

correlation with HPV status. *p ≤ 0.05. **p ≤ 0.01. ***p ≤ 0.001. ****p ≤ 0.0001.

Figure 4. In T cells isolated from advanced head and neck tumors (n = 5), markers of

antigen experience are predominantly found on the CD8+ subset. The CD8+ antigen-

experienced T cells (CD103+CD39+) express higher levels of PD-1 and TIGIT that are

consistent with an “exhausted” phenotype. Expression of CD226 is progressively lost from

the inexperienced CD103-CD39- CD8 T cell population to the experienced CD103+CD39+

CD8 T cell population.

Figure 2. In a CHO cell line expressing human TIGIT, AB154 binds with sub-nanomolar

affinity (0.35 nM). Binding of soluble CD155-Fc to TIGIT was abrogated in the presence of

AB154 with an IC50 of 0.69 nM.

AB154 Binding to Human TIGIT Blocks Interaction with CD155

0.01 0.1 1 10 1000

1×105

2×105

3×105

4×105

AB154 (nM)

MF

I

hTIGIT

EC50 = 0.35 nM

0.01 0.1 1 10 1000

200

400

600

800

1000

AB154 (nM)

MF

I

IC50 = 0.69 nM

hTIGIT

AB154

TIGITFc CD155

CD45

Via

bili

ty

FSC-A

CD

3

CD8

FoxP

3

CD103

CD

39

TregCD4+

CD8+

Treg

CD8+

CD4+

CD103

CD103

TIGIT

CD103- CD39-

CD103+ CD39+

CD103+ CD39-

PD-1 CD226

TIGIT

CD

226

CD8+

Treg CD4+

0

50

100

% o

f C

D3

+

TIGIT PD-1 CD2260

5×103

1×104

1.5×104

Ge

oM

ean

of C

D8

+ T

cells

0

20

40

60

80

100

% o

f C

D8

+ T

cells

CD226-

TIGIT+

CD226+

TIGIT+

CD226-

TIGIT-

CD226+

TIGIT-

CD103- CD39-

CD103+ CD39-

CD103+ CD39+

Total Receptor Coverage Achieved in AB154 Monotherapy Cohort

Figure 6. Complete receptor coverage was observed in all three AB154-dosed patients in

the first cohort of a monotherapy dose escalation study (Dose Level 1). With dosing every

two weeks, AB154 achieved complete inhibition at trough drug levels on all TIGIT-

expressing leukocytes in peripheral blood.

FSC-A

SS

C-A

FSC-A

FS

C-H

CD56

CD

3

CD56

CD

3

CD4

CD

8

CD4

FoxP

3

TregCD8+ T

cells

CD4+ T cellsNK

NKT

T

Pre

-dos

e1h

rD3

D8

D15

D29

D31

D36

D57

0

20

40

60

80

100

120Subject A

Recepto

r O

ccupancy%

(Norm

. to

Pre

-dose)

Pre

-dos

e1h

rD3

D8

D15

D29

D31

D36

D57

0

20

40

60

80

100

120Subject B

Study Time-PointPre

-dos

e1h

rD3

D8

D15

D29

D31

D36

D57

0

20

40

60

80

100

120Subject C

NK cells

T cells

AB154:

Receptor

Occupancy: 0%

CD3

TIG

IT

100%

AB154α-TIGIT(saturating)

Pre-dose Low dose

AB154

High dose

TIGIT-

expressing

cell

TIG

IT (

log2 C

PM

)G

ene E

xpre

ssio

n (

log2 C

PM

)

TIGIT CD155 (PVR) CD226 PD-L1 (CD274) PD-1 (PDCD1)

HNSCC HPV- HPV+ HNSCC HPV- HPV+ HNSCC HPV- HPV+ HNSCC HPV- HPV+ HNSCC HPV- HPV+

ns

***

**

ns

****

****

ns

**

*

ns

ns

ns

ns

****

***

HPV Status in HNSCC (Clinical Test)

CD155

(PVR)