Atara Biotherapeutics : Investor Presentation

INVESTOR PRESENTATION

Q2 2023

AUGUST 8, 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 current war in Ukraine, 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, (ii) 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

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 in relapsed/refractory B-cell NHL

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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

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Landmark Achievement: EbvalloTM is Now Approved in

Europe for the Treatment of EBV+ PTLD!

First ever allogeneic	Groundbreaking
T-cell therapy approval -	achievement validates
addresses high-unmet	our EBV approach
medical need	and platform

First of several		Unique expertise and
anticipated value-		know-how to advance
creating milestones		allogeneic cell
for the company		therapies to approval

Commercialization activities to be led by our EU partner Pierre Fabre

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Note: EBV = Epstein-Barr Virus; EBV+ PTLD = EBV-AssociatedPost-Transplant Lymphoproliferative Disease