Atara Biotherapeutics : Investor Presentation

INVESTOR PRESENTATION

Q3 2023

NOVEMBER 1, 2023

Nasdaq: ATRA

Forward-Looking Statements

This presentation and the accompanying oral presentation contain forward-looking statements 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, including statements regarding our future results of operations and financial position, future transactions, business strategy, product, product candidates, correspondence and discussions with regulatory authorities, regulatory submissions, regulatory approvals, the initiation, timing, progress and results of preclinical studies and clinical trials and our research and development programs, the mechanistic link between EBV and multiple sclerosis and the ability of ATA188 to specifically target such link, ability to sell, manufacture or otherwise commercialize our product and product candidates, research and development costs, timing and likelihood of success, plans and objectives of management for future operations, any royalty payments, our ability to obtain and maintain intellectual property protection for our product and product candidates, and the sufficiency of Atara's cash, cash equivalents, short-term investments to fund its planned operations are forward-looking statements of Atara Biotherapeutics, Inc. ("Atara" or the "Company"). These statements involve known and unknown risks, uncertainties and other important factors that may cause our actual results, performance or achievements to be materially different from any future results, performance or achievements expressed or implied by the forward-looking statements. In some cases you can identify these statements by forward-looking words such as "believe," "may," "will," "estimate," "continue," "anticipate," "intend," "could," "would," "project," "predict," "plan," "expect" or the negative or plural of these words or similar expressions. These forward-looking statements are subject to risks and uncertainties, including those discussed in Atara's filings with the Securities and Exchange Commission (SEC), including in the "Risk Factors" and "Management's Discussion and Analysis of Financial Condition and Results of Operations" sections of the Company's most recently filed periodic reports on Form 10-K and Form 10-Q and subsequent filings and in the documents incorporated by reference therein. These risks and uncertainties include, without limitation, risks and uncertainties associated with the costly and time-consuming pharmaceutical product development process and the uncertainty of clinical success; the COVID-19 pandemic, and the wars in Ukraine and the Middle East, which may significantly impact (i) our business, research, clinical development plans and operations, including our operations in Southern California, Denver and at our clinical trial sites, as well as the business or operations of our third-party manufacturer, contract research organizations or other third parties with whom we conduct business,

1. our ability to access capital, and (iii) the value of our common stock; the impact of future and pending legislation and regulations; the use of our information technology and communication systems and cybersecurity attacks; the sufficiency of our cash resources and need for additional capital, and other factors that may cause our or our industry's actual results, levels of activity, performance or achievements to be materially different from those anticipated by the forward-looking statements. Because forward-looking statements are inherently subject to risks and uncertainties, some of which cannot be predicted or quantified and some of which are beyond our control, you should not rely on these forward-looking statements as predictions of future events. The events and circumstances reflected in our forward-looking statements may not be achieved or occur and actual results could differ materially from those projected in the forward-looking statements. Except as required by applicable law, we do not plan to publicly update or revise any forward-looking statements contained herein, whether as a result of any new information, future events, changed circumstances or otherwise.

Certain information contained in this presentation and statements made orally during this presentation relate to or are based on studies, publications, surveys and other data obtained from third-party sources and Atara's own internal estimates and research. While Atara believes these third-party studies, publications, surveys and other data to be reliable as of the date of this presentation, it has not independently verified, and makes no representation as to the adequacy, fairness, accuracy or completeness of, any information obtained from third-party sources. In addition, no independent source has evaluated the reasonableness or accuracy of Atara's internal estimates or research and no reliance should be made on any information or statements made in this presentation relating to or based on such internal estimates and research.

The content of this presentation is subject to copyright, which will be asserted by Atara and no part of this presentation may be reproduced, stored in a retrieval system, or transmitted in any form or by any means without prior permission in writing from Atara.

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ATARA IS THE FIRST TO DELIVER ON THE TRANSFORMATIVE

POTENTIAL OF ALLOGENEIC T-CELL THERAPY

First Company to Obtain Regulatory Approval for an Allogeneic T-cell Immunotherapy

EbvalloTM (tab-cel®) approved by EMA in December 2022; BLA submission expected Q2 2024

Potential Transformative MS Treatment Uniquely Targeting Root Cause of Disease

ATA188: Phase 2 EMBOLD study primary analysis readout in early November 2023

Best-in-Class Opportunity with Next-Generation Allogeneic CAR T Programs

Leveraging EBV T Cells

ATA3219: IND cleared for Atara's first allogeneic CAR T with preliminary clinical data anticipated in H2

2024

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Highly Experienced Executive Team Dedicated to Transforming the Lives of Patients

Pascal Touchon

President and

Chief Executive Officer

Eric Hyllengren

Chief Financial Officer

Dan Maziasz

Chief Business Officer

AJ Joshi, M.D.

Chief Medical Officer

Cokey Nguyen, PhD

Chief Scientific &

Technical Officer

Jill Henrich

Global Head Regulatory

Affairs & Quality

4

Expanded Global Tab-cel® Partnership with Pierre Fabre Laboratories

Pierre Fabre Laboratories to expand its tab-cel activities to the US and all remaining markets with a global development, manufacturing and commercialization license for up to $640 million in additional consideration and significant double-digit tiered royalties

Substantially all tab-celmanufacturing, clinical, and regulatory activities planned to transfer to Pierre Fabre Laboratories at time of BLA transfer

Atara to receive ~$30 million in upfront cash and initial inventory purchases at closing, and $100 million in potential regulatory milestones through BLA approval

Pierre Fabre Laboratories to reimburse Atara for expected tab-celglobal development costs through BLA approval, and purchase current and future tab-celinventory through BLA transfer

Partnership will expand reach of tab-cel'slife-saving potential to patients worldwide and grow future

revenues for Atara

The companies anticipate a closing date in December 2023 subject to
customary closing conditions including HSR	5

Robust T-Cell Immunotherapy Pipeline

Program	Indication	Target	Preclinical	Phase 1	Phase 2	Phase 3	Registration	Next Milestone
	RR EBV+ PTLD following HCT	EBV		ALLELE	Study		EU Approved	Q2 2024: BLA
Tab-cel® or	and SOT			submission expected
EbvalloTM
(tabelecleucel)	Multi-Cohort(Label-Expansion):	EBV						Dec 2023: Initial Phase 2
	EBV+ cancers(1)						data at ESMO-IO
ATA188	Progressive MS	EBV(2)	EMBOLD Study				Early Nov 2023: Phase 2
			primary analysis readout
ATA3219	B-cell malignancies, including NHL	CD19						H2 2024: Preliminary
						NHL Phase 1 clinical
(Allogeneic)	Autoimmune disease
						data expected
ATA3431	Off-the-shelf, allogeneic CAR T	CD19/CD20						Dec 2023: Preclinical
(Allogeneic)	B-cell malignancies						data presentation at ASH
ATA2271	Autologous CAR T	Mesothelin						Phase 1 study ongoing
(Autologous)	Solid tumors(3,4)
ATA3271	Off-the-shelf, allogeneic CAR T	Mesothelin						Development path
(Allogeneic)	Solid tumors(3)						pending ATA2271 data

Excluding EbvalloTM in EU, these investigational agents are not approved by any regulatory agencies and efficacy and safety have not been established.

EBV+ PTLD: EBV-AssociatedPost-Transplant Lymphoproliferative Disease; RR: rituximab relapsed/refractory; HCT: allogeneic hematopoietic cell transplant; SOT: solid organ transplant; NHL: non-Hodgkin's lymphoma

Atara has entered into an agreement with Pierre Fabre to commercialize Tab-cel® for EBV+ cancers worldwide

Other programs: EBV vaccine and other solid tumor programs

1. Phase 2 multi-cohort initiated in Q3 2020, with possible indications including EBV+ PTLD with CNS involvement, EBV+ PID/AID LPD, EBV+ LMS and other potential EBV-associated diseases
2. Targeted antigen recognition technology; Phase 2 Randomized Controlled Trial
3. Mesothelin is expressed at high levels on the surface of cells in aggressive solid tumors including mesothelioma, triple-negative breast cancer, esophageal cancer, pancreatic cancer and non-small cell lung cancer
4. Atara's CAR T collaboration with MSK will focus on development of a next-generation,mesothelin-targeted CAR T using novel 1XX CAR signaling and PD-1 dominant negative receptor (DNR) checkpoint inhibition technologies.

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Cash, Combined with Certain Anticipated Payments from the Expanded Global Partnership, Sufficient to Fund Planned Operations into Q3 2025

$102.4 million

Cash, cash equivalents, and short-term investments as of September 30, 2023

$71.8 million

Q3 2023

Total Costs and Operating

Expenses

Nasdaq:

ATRA

Atara

Biotherapeutics,

Inc.

101.9 million

Shares Outstanding

as of September 30, 2023*

$51.3 million

Q3 2023

Net Cash Used in Operating

Activities

* Does not include 4.9 million pre-funded common stock warrants outstanding.

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Tab-cel® (EbvalloTM)

Tab-cel® or EbvalloTM (tabelecleucel)

Investigational T-cell	FDA Breakthrough	EU Approval Received in
immunotherapy for	Designation (BTD); BLA	December of 2022
EBV-associated	submission expected in	Followed by UK Approval
ultra-rare diseases	Q2 2024	in May 2023

ATA188

CAR T

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Tab-cel® (Ebvallo™) Addresses Highly Fatal Cancer with Compelling Efficacy and Safety

ASH 2021 data confirm tab-cel® long-term survival benefit

Interim Analysis for Phase 3 pivotal study (ASH 2022)

Updated data from multicenter Expanded Access Program in Europe (ASCO 2023)

86-87%		55 months
2-year OS in CRs &		Median overall
PRs		survival

Tab-cel® Estimated OS Data

S. Prockop et al. ASH 2021 (n=76)

	50% ORR		51.7% ORR
	N = 14		N = 29

HCTSOT

Estimated 1 year OS rate in Responders:

100%

75.2%

• 43 patients (14 HCT, 29 SOT) with EBV+ PTLD R/R to rituximab ± chemotherapy were treated with tab-cel®
• The ORR in all patients was 51% (22/43), with a best overall response of CR (28%; n=12) or PR (23%; n=10)
• Rapid Response: 1-month median time to
  response (range: 0.7-4.7)
• Long Duration of Response: 23-month median DOR in responders (n=22)
• Favorable Safety Profile: No CRS, ICANS , GvHD or organ rejection related to treatment

• Real-World Results Demonstrate

Objective Response Rate (ORR) 67% of 67% in 24 EBV+ PTLD Patients

• 91% Overall Survival (OS) at One	91%
Year for Patients Responding to
Tab-cel Compared to 34% for Non-	34%
Responders

Tab-cel Effectiveness and Safety Profile

Consistent with

Phase 3 ALLELE Study Findings

CRS: cytokine release syndrome; DOR: Duration of Response; GvHD = graft vs host disease; ICANS = immune effector cell-associated neurotoxicity syndrome; HCT: allogeneic hematopoietic cell transplant; SOT: solid organ transplant; Objective response rate (ORR) = complete response (CR) + partial response (PR); OS = overall survival; PD = progressive disease

Prockop et al. ASH 2022, datacut from Q4 2021; Sanz J et al. ASH 2021. Abstract #1454. 2. Dharnidharka V et al. ASH 2021. Abstract #2528.

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Patients in Europe Now Receiving EBVALLOTM in the Commercial Setting

Phased Launch		Transformative
	Value
Country-by-country pricing
	Significant impact for
and reimbursement
Meaningful Commercial	patients and value for
negotiations underway
healthcare system
	Opportunity
	PTLD first, followed
	by potential Multi-Cohort label
	expansion

European commercialization activities to led by Pierre Fabre Laboratories

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