Orally Bioavailable Small Molecule CD73 Inhibitor Reverses

Immunosuppression by Reduction of Adenosine Production

(Abstract #1242)

Xiaohui Du ORIC PharmaceuticalsAACR Annual Meeting 4/2020

Disclosure

• Xiaohui Du is an employee of ORIC Pharmaceuticals

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CD73 is required for adenosine production and linked to therapy resistance

3

T cell priming

T cell expansion

T cell activation / cytolytic activity

DC maturation / activation

Macrophage M1 polarization

NK degranulation

Therapeutic Hypothesis

• CD73 inhibition may enhance activity of chemotherapy and immunotherapy

• Small molecule approach may differentiate in dosing regimen and tumor penetration

• Overexpressed across cancer

types driving local elevation of

adenosine

• Overexpression correlated with

poor prognosis

• Mediates immunosuppression

and chemoresistance via

adenosine production

CD73

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Surveying linker region towards exo phosphonate led to novel starting point

4

Biochem IC50 :

Rat PO :

0.52 nM Biochem IC50 :

Rat PO Cmax :Rat PO AUCinf :

25 nM

0.12 µM

0.56 µM*hrNo oral exposure

Biochem IC50 :

Rat PO Cmax :

Rat PO AUCinf :

328 nM

ND

ND

Biochem IC50 :

Rat PO Cmax :

Rat PO AUCinf :

88 nM

ND

ND

Biochem IC50 :

Rat PO Cmax :

Rat PO AUCinf :

29 nM

0.11 µM

0.66 µM*hr

• Replace bisphosphonate motif to reduce overall polar surface area and charge

• Internal-capped phosphonate tolerated; linker length to exo phosphonate important

• Ether-linked phosphonic acid shows early signs of oral bioavailability

Muller J. Med. Chem. 2015, 58, 6248.

Biochem IC50 :

Rat PO :

2996 nM

No oral exposure

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Co-crystal structure of 5 with CD73 provided possible directions for potency

improvement

5

• Can a-substitution further improve potency?

5: IC50 = 29 nM

substitution?

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a-Substitution identified key functional groups to increase potency

6

• The oxygen in CH2OR possibly interacts with CD73

• Disubstituted analogs 21 and 22 are more potent than mono-substituted 8 and 9

10 11 12 13 14

28 559 108 193 387

Compound 6 7 8 9

CD73 IC50

(nM) 11 18 2.4 0.96

H

Compound 15 16 17

CD73 IC50

(nM) 1.3 >5000 97

18 19 20 21 22

10 23 31 0.57 0.53

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Discovery of potent and orally bioavailable CD73 Inhibitor OP-5244

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Compound Structure

Biochem H1568 EMT6 Mouse PO (200mg/kg)

IC50

(nM)

EC50

(nM)

EC50

(nM)

AUCinf

(µM*h)

Cmax

(µM)t1/2 (hr)

1 0.52 - - no oral exposure

AB680* 0.86 3.3 198Clinical trial (IV

formulation)

23

OP-52440.25 0.79 14 45.1 42.2 3.3

24 1.0 10.4 - -

*Bowman C.E. et al, Biochemistry

2019, 58, 3331-3334.

• OP-5244 has comparable potency to bisphosphonic acid series

• OP-5244 shows good oral bioavailability in mouse

Co-crystal structures confirmed key interactions for potency

improvement of OP-5244

8

• CH2OH/CH2OMe H-bonds with Arg 354/395

• Replaced the phosphonate H-bond interactions

OP-5244: IC50 = 0.25 nM

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OP-5244 fully suppresses ADO Production

9

• OP-5244 inhibited ADO production from AMP in tumor cells & CD8+ T Cell (EC50 = 0.22 nM)

• A CD73-targeted antibody incompletely inhibits AMP conversion to ADO

10 -2 100 102 104

0

20

40

60

80

100

CD73-driven Adenosine Production

Concentration (nM)

% m

ax A

den

osin

e

H1568

EMT6

CD8+

T cells

H1568

OP

-52

44

anti-C

D73

mA

b

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OP-5244 rescues immunosuppressive effects of AMP on T cells

10

acti

vate

d

25u

M A

MP

1000

nM

333

nM

111n

M

37

nM

12.3

nM

4.1

nM

0

10

20

30

40

50

60

70

80

90

100

% T

Ce

lls

Pro

life

rati

ng

OP-5244+AMP

OP-5244 rescued CD8+ T cell proliferation and cytokine (IFNg and TNFa) production

in the presence of AMP

T cell proliferation

ac

tiv

ate

d

25

uM

AM

P

10

00

nM

33

3.3

nM

11

1.1

nM

37

.0n

M

12

.3n

M

4.1

nM

0

1000

2000

3000

4000

5000

IFNg

pg

/ml

ac

tiv

ate

d

25

uM

AM

P

10

00

nM

33

3.3

nM

11

1.1

nM

37

.0n

M

12.3

nM

4.1

nM

0

50

100

150

200

250

300

TNFa

pg

/ml

OP-5244+AMP OP-5244+AMP

Cytokines

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OP-5244 reduces tumor size, ADO/AMP ratio and reverses immunosuppression

in vivo

11

Veh

icle

OP-5

244

0

100

200

300

Tu

mo

r V

olu

me (

mm

3)

✱

Veh

icle

OP-5

244

0

5

10

15

20

25

Ra

tio

of

Ad

en

os

ine

/AM

P ✱✱✱✱

Pla

sma

Tumor

0.01

0.1

1

10

Un

bo

un

d C

on

c.

(M

)

EMT6 Cell ADO EC90,unb

Veh

icle

OP-5

244

0

500

1000

1500

Tu

mo

r V

olu

me (

mm

3)

Veh

icle

OP-5

244

0

5

10

1530

35

% C

D8

+ o

f to

tal

CD

45

+

✱

Veh

icle

OP-5

244

0

2

4

6

15

20

25

CD

8 /

Tre

g r

ati

o

✱✱

EMT-6 Murine Breast Cancer Model

in BALB/c Mice

E.G7-OVA Murine T Cell Lymphoma Model

in C57BL6 Mice

• OP-5244 exhibits anti-tumor effects as a single agent

• OP-5244 modulates intra-tumoral adenosine pathway

• OP-5244 activates tumor-mediated immune response

Tumor Size ADO/AMP Modulation Exposure of OP-5244 Tumor Size CD8+/Treg RatioCD8+ Cytotoxic T cells

• OP-5244: 150 mg/kg, BID x 16, PO

• Tumor measurement on Day 15

• TIL analysis on Day 16

• *, p<0.05: **, p<0.01 by t-test

• OP-5244: 15 mg/kg/day mini pump infusion

• Tumor measurement on Day 13

• Tumor adenosine, exposure measurement on Day 13

• *, p<0.05: ****, p<0.0001 by t-test

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Upcoming AACR presentations featuring ORIC-533 development candidate

12

• Poster #10268: An orally bioavailable inhibitor of CD73 reverts intratumoral immunosuppression and

promotes anti-tumor responses

– Significant single agent anti-tumor activity of ORIC-533 associates with reversed immunosuppression

• Poster #4317: CD73 inhibition with a novel orally bioavailable small molecule blocks adenosine production

and rescues T-cells activation in high AMP conditions

0 5 10 15 20

0

500

1000

1500

2000

days post implantation

Tu

mo

r V

olu

me

(m

m3) Vehicle

ORIC-533 150 mg/kg, QD, PO

Tumor Adenosine

Veh

icle

150

mg/k

g

0

100

200

300

400

AD

O C

on

c.

(µM

)

Tumor Growth Inhibition Tumor T Cell Modulation

Veh

icle

150

mg/k

g

0

5

10

15

%CD8+ of CD45+

% o

f C

D45

+

*

Veh

icle

150

mg/k

g

20

40

60

80

100

%Mem/Eff of CD8+

% C

D62L

- of

CD

8+ T

*****

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Conclusions

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• Designed novel orally bioavailable mono-phosphonic acid CD73 inhibitors

• Ether phosphonic acids with a,a-disubstitution gained additional interactions with CD73

and further potency enhancement

– equipotent relative to the bisphosphonic acid series

• Small molecule CD73 inhibitor represents a potential therapeutic approach to reverse

immunosuppression within the tumor microenvironment

– OP-5244 fully rescues T cell proliferation and cytokine production from ADO-mediated

suppression in vitro

– OP-5244 reduces tumor size, modulates intra-tumoral ADO pathway and reverses

immunosuppression in vivo

– OP-5244 is a prototype for further optimization/clinical candidate identification

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Acknowledgements of the ORIC CD73 team

14

Wayne Kong

Xi Chen

Xiaohui Du

Yuping Chen

Zhensheng Wang

PepTech

Proteros biostructures Gmbh

Jessica Sun

John Eksterowicz

Lori Friedman

Melissa R. Junttila

Natalie Yuen

Qiuping Ye

Tatiana Zavorotinskaya

Todd Metzger

Tom Huang

Valeria Fantin

Bob Warne

Brenda Chan

Brian Blank

Chudi Ndubaku

Daqing Sun

Dena Sutimantanapi

Erica Jackson

Frank Duong

Jae Chang

Jared Moore

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