ASCO-GI: Ongoing ARC-8 Dose-escalation Overview – January 15, 2021

OUR VISION: COMBINING TO CURE

WITH BEST-IN-CLASS CANCER THERAPIES

ASCO-GI: ONGOING ARC-8DOSE-ESCALATION OVERVIEW

JANUARY 2021

NYSE: RCUS

Forward-looking Statements/Safe Harbor

This presentation contains forward-looking statements about Arcus Biosciences, Inc. ("we," "Arcus" or the "Company") made pursuant to the safe harbor provisions of the Private

Securities Litigation Reform Act of 1995. All statements other than statements of historical facts contained in this presentation are forward-looking statements, including statements about our strategy, advantages, progress and pace of our development programs, anticipated milestones and associated timing, potential benefits associated with our Gilead and AstraZeneca collaborations, and expectations regarding our available cash and investments. These forward-looking statements are subject to a number of risks, uncertainties and assumptions that may cause actual results to differ materially from those contained in any forward-looking statements we may make, including, but not limited to: risks associated with preliminary or interim data and the emergence of adverse events or other undesirable side effects; differences in interpretation of our clinical trial results; risks associated with our collaboration arrangement with Gilead including our dependence on Gilead for the successful development and commercialization of our investigational products; the inherent uncertainty associated with pharmaceutical product development and clinical trials; risks associated with the impact of the COVID-19 pandemic; delays in our clinical trials due to difficulties or delays in the regulatory process, enrolling subjects or manufacturing or supplying product for such clinical trials; changes in the competitive landscape; our limited operating history and our ability to manage our growth; and risks regarding our license and collaboration agreements and our ability to obtain and maintain intellectual property protection for our product candidates.

We operate in a very competitive and rapidly changing environment. New risks emerge from time to time. It is not possible for our management to predict all risks, nor can we assess the impact of all factors on our business or the extent to which any factor, or combination of factors, may cause actual results to differ materially and adversely from those anticipated or implied in the forward-looking statements. Further information on these and other factors that could affect the forward-looking statements made herein are described in our most recent Annual Report on Form 10-K and Quarterly Report on Form 10-Q filed with the U.S. Securities and Exchange Commission.

You should not rely upon forward-looking statements as predictions of future events. Except as required by law, neither we nor any other person assumes responsibility for the accuracy and completeness of the forward-looking statements. We undertake no obligation to update publicly any forward-looking statements for any reason after the date of this presentation to conform these statements to actual results or to changes in our expectations.

The Arcus name and logo are the property of Arcus. All other trademarks included herein are the property of their respective owners and are used for reference purposes only. Such use should not be construed as an endorsement of Arcus.

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© Arcus Biosciences 2021

2021 Will Be a Pivotal Year for Arcus

• Four clinical-stage product candidates rapidly advancing towards registrational trials
• • Two essential backbone antibodies:
  • • AB154 (Domvanalimab): Anti-TIGIT mAb - randomized interim-analysisread-out for ARC-7 planned in 2Q:21 (in 1L NSCLC, PD-L1 ≥ 50%); Advancing ARC-10 into registrational trial (to support both Dom + Zim and Zim approvals)
    • AB122 (Zimberelimab): Anti-PD-1 mAb with clear line-of-sight to commercialization; enables portfolio combination strategies
  • Two internally discovered small molecules targeting the adenosine axis:
  • • AB928 (Etrumadenant): First dual A2aR / A2bR antagonist to enter the clinic
    • AB680: First small-molecule CD73 inhibitor to enter clinical development; both IV and oral formulations in development
• Six Arcus sponsored randomized trials are ongoing or soon-to-be initiated with preliminary data from several of these randomized trials expected in 2021
• At least two additional product candidates expected to enter clinical development in 2021
• • AB308: TIGIT antibody (FcR enabled) to target heme malignancies
  • Small molecule programs targeting HIF2a, Axl and PAK4 are approaching development candidate selection
• Well-positionedto unlock the value of our pipeline
• • ~$785M in cash as of 9/30/20 and funding into at least 2023
  • "All-in"Gilead partnership provides significant financial and other resources to more fully exploit our portfolio
  • Recently announced clinical collaboration with AstraZenca for PACIFIC-8 (Phase 3 trial in Stage III NSCLC) further validates the therapeutic potential of domvanalimab

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© Arcus Biosciences 2021

Broad Clinical Program Targeting Major Cancers, Including Those Not Responsive to PD-(L)1 Therapy

WT 1L

EGFRm 2L+

NSCLC

WT 1L

PD-L1 High

Stage 3

1L

CRPC 2L+ 2L+

2L

CRC 3L

>3L

PDAC 1L

Phase 1		Phase 1b		Randomized - Phase 2		Pivotal/Phase 3

Zim ± Dom ± Etruma

Zim + Carbo/Pem ± Etruma

Dom + Zim vs. Zim vs. Chemo

Durva ± Dom1	PACIFIC-8

Etruma + Zim + Enza

Etruma + Zim + Doce

Etruma + Zim ± AB680

Etruma + Zim + FOLFOX* vs.

FOLFOX*

Etruma + Zim + FOLFOX* vs. Rego

Etruma Combinations

AB680 + Zim + Gem/Nab-pac

	Zim: zimberelimab; Dom: domvanalimab; Etruma: etrumadenant; Rego: regorafenib	PLANNED 2021
	Gem: gemcitabine; FOLFOX: (folinic acid, fluorouracil; oxaliplatin); Nab-pac:nab-paclitaxel; Doce: docetaxel;
	Carbo: carboplatin; Pem: pemetrexed, Durva: durvalumab; Enza: enzalutamide
4	NSCLC: non-small cell lung cancer; CRPC: castrate-resistant prostate cancer; CRC: colorectal cancer; PDAC: pancreatic ductal adenocarcinoma
1Clinical collaboration with AstraZeneca; AZ will be the primary sponsor of PACIFIC-8.	© Arcus Biosciences 2021
	* +/- biologic

Multiple Important Readouts Are Expected In 2021

	COMBINATION / ARMS	SETTING	MILESTONE	ANTICIPATED TIMING
	AB680 + Zim +	1L Pancreatic Cancer	- Initial dose-escalation	▪	January 2021
	Gem/Nab-pac		data		(ASCO GI)
			- Additional data from	▪	2H21
			dose-escalation
	Zim + Dom vs. Zim vs.	1L NSCLC (PD-L1 ≥ 50%)	- Conduct of interim	▪	2Q21
	Zim + Dom + Etruma		analysis
			- Presentation of IA data	▪	2H21
	Etruma + Zim + Carbo/Pem	TKI R/R EGFR+ NSCLC	- Initial randomized data	▪	2H21
	vs. Zim + Carbo/Pem
	Etruma + Zim + SOC	Metastatic castrate-	- Preliminary data from	▪	2Q21
	vs. SOC	resistant prostate cancer	initial cohorts
		(mCRPC)	- Initial randomized data	▪	2H21
	Etruma + Zim + FOLFOX	2L/3L/3L+ Colorectal	- Initial randomized data	▪	1H22
	vs. SOC	cancer	for 2L/3L cohorts; single-
			arm data for 3L+

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© Arcus Biosciences 2021

The Adenosine Axis Plays a Well-Established and Critical

Role in Suppression of the Immune Response

				Adenosine production leads to significant
		immunosuppression in the tumor microenvironment
Extracellular ATP is released by					A2aR
dying cells, particularly when
triggered by immunogenic	Adenosine is generated from		NK Cells			↓ cytotoxicity
chemotherapy
ATP by the enzymatic action
	of CD39 and CD73
		A2aR
	ATP	AMP	T Cells
ATP		Adenosine
				↓ effector function
							↓ cytotoxicity
ATP				DC, TAM,	A2bR A2aR		↓ DC / T-cell activation
	CD39	CD73
	MDSC

6 AB928: Dual A2aR/A2bR receptor antagonist; AB680: Small-molecule CD73 inhibitor

© Arcus Biosciences 2021

Arcus is a Leader in the Development of Therapeutics that

Target the Adenosine Axis

AB680 inhibits CD73, an enzyme that plays a key role in the conversion

of AMP to adenosine, therefore acting upstream of etruma

Etruma blocks adenosine from binding to A2aR

and A2bR, blocking immunosuppression

Extracellular ATP is released by
dying cells, particularly when
triggered by immunogenic	AB680 blocks the function
chemotherapy
of CD73, preventing the
	conversion of AMP to adenosine

ATP	AMP
ATP	Adenosine
	AB680

ATP

CD39

A2aR

Etruma

NK Cells

↑ cytotoxicity

A2aR

T Cells

Etruma

↑ effector function ↑ cytotoxicity

	A2bR A2aR		Etruma
DC, TAM,			↑ DC / T-cell activation
MDSC

7 Etruma: Dual A2aR/A2bR receptor antagonist; AB680: Small-molecule CD73 inhibitor

© Arcus Biosciences 2021

AB680 is a Unique, Highly Potent and Selective Small

Molecule CD73 Inhibitor

AB680 is a tight-binding, reversible CD73 inhibitor (Ki hCD73 = 4.9 pM)

Ki determined in collaboration with Prof. Rafael Guimaraes da Silva, Univ. of St. Andrews

Biochemistry, 2019, 58, 3331-3334

Extreme Potency of AB680

Against CD73

Target	IC50 (nM)
hCD73-CHO	0.070
hCD73	0.043
(soluble)
Human CD8+	0.008
T Cells
hPBMC	0.011

Other features:

IV administration (oral formulation also in development)

Extremely long (~4 days) half-life, enabling dosing every two weeks

8 X-ray data collected by N. Sträter; Univ. of Leipzig

© Arcus Biosciences 2021

Mechanism of AB680 Potentially Offers Several Advantages

Over CD73 Antibodies

CD73 Antibodies Have Limitations		AB680 (Small Molecule)

The most advanced antibodies in the clinic are being developed by AZN (Oleclumab) and BMS

• As antibodies, unlikely to achieve a small molecule's permeability of tumor tissue (important since adenosine exerts its biology where it is formed by CD73)
• Antibodies are unable to completely inhibit CD73 enzymatic activity and are even less effective against soluble CD73

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• First small-molecule inhibitor of CD73 to enter the clinic
• Extremely potent and selective against bothtumor and soluble CD73 and orders of magnitude more potent than CD73 antibodies
• Established safety profile as a single agent in healthy volunteers andin combination with chemo/anti-PD-1 in pancreatic cancer patients
• PK/PD profile has shown complete target coverage 24/7 in humans
• Flexibility to use as IV or oral formulation

© Arcus Biosciences 2021

AB680 Monotherapy Inhibits Intratumoral CD73 and Delays

Tumor Growth in Mouse Tumor Models

AB680 Inhibits CD73 Enzymatic

Activity Within Tumors

)
(%	1 0 0
is	8 0
r o ly s
6 0
H y d
4 0
A M P
2 0
-
5
C	0
3
1	0 .1	1	1 0	1 0 0	1 0 0 0

L o g [A B 6 8 0 ], n M

AB680 Monotherapy Inhibits

Tumor Growth

6 0 0

V e h i c l e

)

3

m	A B 6 8 0 1 0 m g / k g
( m
4 0 0
m e
* *
V o l u
o r	2 0 0
T u m

0
0	5	1 0	1 5	2 0

D a y s p o s t i m p l a n t a t i o n

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© Arcus Biosciences 2021

Healthy Volunteer Study Demonstrated AB680 Achieved Complete Target Coverage with Q2W Dosing

Target coverage was achieved, even at 25mg every two weeks

(Q2W), given the exquisite potency of AB680

Plasma Concentration (ng/mL)

10000

1000

100

10

1

0.1

0

2

4

6

8

10

12

14

Time (day)

					Initial dose for
					ARC-8 dose
				25 mg (t1/2 ~ 4 days)
				escalation
					study
				16 mg
				8.0 mg
				4.0 mg
				2.0 mg
				0.6 mg
				0.1 mg

11 aAB680 was administered (30-60 min) by i.v. infusion on day 0.

© Arcus Biosciences 2021

Pancreatic Cancer Was Selected as the Initial Indication

for AB680 Given High CD73 Expression

High CD73 levels in PDAC may be a reflection of the observed correlation between CD73 expression and oncogenic

drivers such as KRAS

Oncogenic Drivers of CD73 Expression

12 Analysis of Tumor Cancer Genomic Atlas (TCGA) performed by Arcus

© Arcus Biosciences 2021

Phase 1/1b Clinical Study in Advanced 1L Metastatic

Pancreatic Ductal Adenocarcinoma (PDAC)

• Dose escalation and dose expansion study
• Preliminary data on safety and early clinical activity from the dose-escalation portion were presented at ASCO GI
• Explored four escalating doses of AB680 in combination with Zimberlimab (anti-PD-1) and SOC chemotherapy (Nab-Pac/Gem)
• Dose-expansionphase has been initiated and expected to enroll quickly given high investigator enthusiasm

13 Presented at ASCO-GI 2021 (GA Manji et al. Abstract #404)

PDAC Background

• Devastating disease with a 5-year survival rate of just 9%
• Abraxane®, in combination with gemcitabine (NP/Gem), was the last treatment approved (in 2013) based on an ORR of 23%(1)
• PD-1antibodies have not shown any benefit to date when combined with chemotherapy(2)(3)
• Very few new therapies in development

The low ORR w/ SOC and high prevalence of activated / mutated KRAS pathway (>90%) (4) makes PDAC an ideal tumor type for AB680

1. Von Hoff DD, et al. N Eng J Med. 2013; 369(18):1691-1703.
2. Zev A., et al., Clin Cancer Res. 2020; 26(18): 4814.
3. Weiss GJ, et al., Invest New Drugs. 2018; 36(1):96.
4. Waters and Der, Cold Spring Harb Perspect Med 2018;8:a031435.

© Arcus Biosciences 2021

Dose Escalation Designed to Identify the RDE and

Detect Evidence of Clinical Activity (ORR / PFS)

IV, intravenously; Gem, gemcitabine; NP, nab-paclitaxel; PDAC, pancreatic ductal adenocarcinoma; Q2W, every 2 weeks; R, randomization;

RDE, recommended dose for expansion; Zim, zimberelimab.

14 Presented at ASCO-GI 2021 (GA Manji et al. Abstract #404)

© Arcus Biosciences 2021

Ph1/1b Clinical Study in Front-line Metastatic PDAC

Patients

Patient Baseline Characteristics

15 Presented at ASCO-GI 2021 (GA Manji et al. Abstract #404); DCO: Nov. 11, 2020

© Arcus Biosciences 2021

Preliminary Safety Data Demonstrate AB680

Adds Minimal Toxicity to Chemotherapy

Summary of Treatment Emergent AEs

• 1 DLT (Gr2 autoimmune hepatitis) in the 50mg AB680 cohort; resolved completely with steroid treatment and the patient resumed treatment
• The most common TEAEs were fatigue (68%), anemia (53%), alopecia (42%), diarrhea (42%) and neutrophil count decreased (42%)
• Study drug-related TEAEs were reported by 8/19 (42%) patients; 4 patients had Gr 1 or 2 study-drug related TEAEs and 4 patients experienced Gr 3 study drug- related TEAEs
• There were no patients who discontinued study treatment due to TEAEs

No significant toxicity has been observed over that expected for the NP/Gem backbone alone

16 Presented at ASCO-GI 2021 (GA Manji et al. Abstract #404); Nov. 11, 2020

© Arcus Biosciences 2021

Time on Treatment and RECIST v1.1 Response

17 Presented at ASCO-GI 2021 (GA Manji et al. Abstract #404); Dec. 9, 2020

© Arcus Biosciences 2021

Waterfall Plot of Best Percent Change from Baseline

in Sum of Target Lesions

88% (15/17) of Evaluable Patientsin the Dose-Escalation Portion Experienced Tumor Shrinkage

IV, intravenously; NP/Gem, nab-paclitaxel/gemcitabine; Q2W, every 2 weeks; Zim, zimberelimab.

18 Presented at ASCO-GI 2021 (GA Manji et al. Abstract #404); Dec. 9, 2020

*

*

*

* Confirmed Response

© Arcus Biosciences 2021

Spider Plot of Percentage Change from Baseline

in Sum of Target Lesions

7 of 10 Patients with Stable Disease at First Disease Evaluation

Experienced Further Shrinkage at the Next Evaluation

IV, intravenously; NP/Gem, nab-paclitaxel/gemcitabine; Q2W, every 2 weeks; Zim, zimberelimab.

19 Presented at ASCO-GI 2021 (GA Manji et al. Abstract #404); Dec. 9, 2020

© Arcus Biosciences 2021

BOR, ORR & DCR Across All Dosed Cohorts

Best Overall Response#	Dose-escalation Cohorts

Number (%) of Subjects
25mg	50mg	75mg	100mg	Overall
	(N=4)	(N=6)	(N=3)	(N=4)	(N=17)
Complete Response (CR)	0	0	0	0	0
Partial Response (PR)	1 (25)*	2 (33)	1 (33)	3 (75)	7 (41)
Stable Disease (SD)	1 (25)	4 (67)	2 (67)	1 (25)	8 (47)
Progressive Disease (PD)	1 (25)**	0	0	0	1 (6)
Not Evaluable	1 (25)***	0	0	0	1 (6)
Objective Response Rate	1 (25)	2 (33)	1 (33)	3 (75)	7 (41)
Disease Control Rate§	2 (50)	6 (100)	3 (100)	§	11/13 (85)

*PR has converted to a full CR post poster submission **Patient was noted by investigator to be SD; continues on therapy ***Patient progressed prior to first disease assessment

#Investigator Assessed; ORR is defined as the percentage of participants with a best overall response (BOR) of CR or PR based on RECIST 1.1 as assessed by the investigator §Disease control rate represents any PR, CR or SD for 16 weeks or more. No patient in the 100mg treatment group has been on study >16 weeks; all remain on study treatment.

20 Presented at ASCO-GI 2021 (GA Manji et al. Abstract #404); DCO: Dec. 9th, 2020

© Arcus Biosciences 2021

Illustrative Patient Who Experienced a Significant

Reduction in Tumor Size and CA 19-9

• CA 19-9 is a circulating blood marker that is elevated in patients with active pancreatic cancer. Pancreatic cancer patients who experience a reduction in 19-9 with treatment frequently have extended survival compared with patients who do not (1)
• This patient, and others on the ARC-8 study, have experienced a reduction in disease burden, reduction in symptoms associated with pancreatic cancer and important clinical benefit in this devastating disease

21	Presented at ASCO-GI 2021 (GA Manji et al. Abstract #404); Dec. 9, 2020	(1) Chiorean EG, et al. Ann Oncol. 2016 Apr; 27(4): 654-660.

© Arcus Biosciences 2021

Preliminary Dose-Escalation Data Demonstrate

Early Signs of Clinical Activity for AB680

• AB680, in combination with NP/Gem and zimberelimab, has a manageable safety profile consistent with that expected for each agent alone and demonstrated early signals of clinical activity
• AB680 combination therapy in 17 efficacy-evaluablepatients resulted in a 41% objective response rate(7/17)1 which compares favorably with chemotherapy (23% ORR for NP/Gem)2
• 83% (10/12) of evaluable patients from the first three cohorts continue on treatment as of DCO of 12/9/20 with a median time on treatment of 180 days
• 100mg q2w was selected as the recommended dose for expansion (RDE), which is currently ongoing

Presented at ASCO-GI 2021 (GA Manji et al. Abstract #404)

1Of the partial responses (PRs), 3 are confirmed responses and of the 4 unconfirmed responders, 3 responded at the first tumor assessment and the fourth responded at the second tumor assessment, and all remain on study

22 2Von Hoff DD, et al NEJM 369(18):1691-1703 (2013)

© Arcus Biosciences 2021

Near-term Plans for AB680 and ARC-8

Next Steps for ARC-8

• In December, we initiated the Phase 1b dose-expansion portion of the study using the 100mg q2W dose of AB680
• Given the lack of additive toxicity with AB680, a 125mg dosing cohort will be explored in the ongoing dose- escalation portion
• A control arm of AB680 + NP/Gem is expected to open shortly

Next Data Read-outs for ARC-8

• Duration of Response (DoR) and PFS data from the dose-escalation portion are expected to be presented
  at a medical conference later in the year

23 Presented at ASCO-GI 2021 (GA Manji et al. Abstract #404); 1Von Hoff DD, et al. NEJM 369(18):1691-1703(2013)

© Arcus Biosciences 2021

Data Provide Important POC for the Molecule and

Therapeutic Hypothesis

As CD73 is ubiquitous in cancer, AB680 has broad development potential

Already Planned Addition to		Additional		Novel, Intra-portfolio
Existing Platform Trials		Tumor Types		Combinations

Objective: Efficiently explore the potential synergy between AB680 and Etruma

AB680 + Etruma +/-

Zimberelimab arm

AB680 + Etruma +

Zimberelimab arm

Objective: Evaluate AB680 in other tumor types associated with high levels of CD73, e.g. CRC, NSCLC, Gastric / Esophageal

Objective: Rationally combine AB680 with other Arcus- controlled molecules and/or existing therapies

Setting	Potential Combination
	▪	Etruma
Arcus Molecules	▪	Zim
▪	Dom
	▪	Others
SOC	▪	Chemotherapy
▪	Radiation

24 Analysis of Tumor Cancer Genomic Atlas (TCGA) performed by Arcus

© Arcus Biosciences 2021

ADDITIONAL ONGOING ADENOSINE-AXIS TRIALS

Study to Evaluate Etruma (AB928) + Zim + Chemotherapy in EGFRmut Non-Small Cell Lung Cancer

• Study design schema for dose-escalation and dose-expansion of Etruma + anti-PD- 1 + Carboplatin/Pemetrexed (chemo) in NSCLC patients

• Dose-expansion phase:

‒ Participants must have a sensitizing
EGFR mutation and failed treatment
with 1 TKI (or 1-2 TKIs for tumors with
T790M mutation)
‒ Previous treatment with chemotherapy
or PD-1/PD-L1 therapy is not allowed
‒ Preliminary data presented at ESMO
2020	Dose Expansion & Randomization
‒ Control arm opened after passing
futility assessment	Zimberelimab IV Q3W + C/P +/-
• Next Steps:		Etrumadenant
	(n ≤ 40 both arms)
‒ Initial randomized data to be
presented 2H21
	C/P: carboplatin/pemetrexed; RDE: recommended dose for escalation; TKI: tyrosine kinase inhibitor

26 A. Spira et al, ESMO (2020); presentation no.1309P; NCT03846310

© Arcus Biosciences 2021

Platform Study to Evaluate Etruma (AB928) across Multiple Lines of Therapy in mCRPC

• Platform study in mCRPC to assess the safety and efficacy of the addition of Etruma (AB928) + Zim to standard of care Enzalutamide and Docetaxel
• • Supports early randomization and proof of concept if activity signal is seen in Stage 1
• Evaluating Etruma novel combinations for late-line patients without available standard of care
• • Preliminary data from initial cohorts 2Q21
  • Expansion of these cohorts based on initial signals

Stage 1 / Phase 1b

Etrumadenant

+ Zimberelimab R

+ Enzalutamide

Etrumadenant

+ Zimberelimab R

+ Docetaxel

	Etrumadenant + Zimberelimab
R	Etrumadenant + Zimberelimab
+ AB680

Stage 2 / Phase 2

Etrumadenant + Zimberelimab

• Enzalutamide
  SOC

Etrumadenant + Zimberelimab

• Docetaxel
  SOC

Etrumadenant + Zimberelimab

Etrumadenant + Zimberelimab + AB680

Etrumadenant + AB680

Etrumadenant + AB680

27 Subudhi e.t al, ESMO (2020); presentation no.687TiP; NCT04381832

© Arcus Biosciences 2021

Platform Trial in 2L and 3L mCRC

Initial randomized data for 2L/3L cohorts; single-arm data for 3L+ in 1H22

Adenosine Receptor Antagonist + Checkpoint Inhibitor + Platinum-based

Chemotherapy Combination Therapy for non-MSI-H/TMB mCRC

Cohort A

Cohort B

Cohort C

Safety Run-in cohort

2L	Post-FOLFOX/FOLFIRI

3L	Post-Oxali and Irino

>3L	Post-Oxali and Irino

AB928 + Zimberelimab + FOLFOX + Bev* (n=6-12)

		AB928 + Zimberelimab +
		FOLFOX + Bev* (n=60)					PFS
R
FOLFOX + Bev* (n=30)
		AB928 + Zimberelimab +					PFS
		FOLFOX + Bev* (n=70)
R					+
		Regorafenib (n=35)					OS
						Crossover
						at progression
						allowed
		Stage 1					Stage 2
	AB928 + Zimberelimab + Agent X				Expand to n=40
		(n=15)
	AB928 + Zimberelimab + Agent Y				Expand to n=40
		(n=15)

*Bev will be included for all patients in whom it is not contraindicated

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© Arcus Biosciences 2021