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.

Investor Presentation January 11, 2021

Nasdaq: ATRA Exhibit 99.1

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, business strategy, product candidates, regulatory approvals, the initiation, timing, progress and results of preclinical studies

and clinical trials and our research and development programs, ability to sell, manufacture or otherwise commercialize our product candidates, research and development costs, timing and likelihood of success, plans and objectives of management for

future operations, any royalty payments, and our ability to obtain and maintain intellectual property protection for our product candidates, are forward-looking statements. 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. These forward-looking statements

are subject to risks and uncertainties, including those discussed in Atara Biotherapeutics' 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. 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 relates to or is 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

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Ola PTLD champion Ayden PTLD champion

Jon PTLD champion Doug PTLD champion Jessica PTLD champion 1982-2019 Atara mourns the loss of Jessica, who passed away on September 25, 2019 while awaiting a new heart and kidney transplant. Her memory continues to fuel our urgency in developing new

therapies for devastating diseases. Our mission is to transform the lives of patients with serious diseases through pioneering science, teamwork and a commitment to excellence Pioneering Off-the-Shelf, Allogeneic T-cell Immunotherapies Dan MS

Highly Experienced Executive Team

Dedicated to Transforming the Lives of Patients Kristin Yarema, Ph.D. Chief Commercial Officer Pascal Touchon President and Chief Executive Officer Joe Newell Chief Operations Officer AJ Joshi, M.D. Chief Medical Officer Utpal Koppikar Chief

Financial Officer Jakob Dupont, M.D. Head of Research and Development

We Are a Leading Allogeneic T-Cell

Immunotherapy Company ATA188: Potentially Transformative MS Treatment in Randomized Controlled Trial Tab-cel : First-In-Kind, Late-Stage, Oncology Program Differentiated Allogeneic Cell Therapy Platform Next-Gen

Allogeneic CAR T Portfolio, Validated by Bayer Collaboration on Mesothelin-Targeted CAR T Scalable EBV T Cell platform and technologies to develop multiple allogeneic cell therapies BLA completion expected in Q3 2021,

underpinned by strong clinical data Competitive programs designed to address current limitations of autologous and allogeneic CAR T Working towards placebo-controlled data, expected within ~2 years, to enable pivotal studies and partnering

opportunities Advanced process science and wholly owned pre-commercial manufacturing capabilities attractive to potential partners Proven Technical Capabilities EBV = Epstein-Barr Virus; BLA = Biologics License Application; BTD = Break Through

We Are Rapidly Advancing Across

Multiple Fronts Today Within Next 24 months Tab-cel ATA188 CAR T Allogeneic T-cell Platform Expertise Nearing BLA initiation Potential for first allogeneic T-cell immunotherapy on the market in 2022 Growing open label clinical dataset

suggesting transformative potential in MS Disability improvement data from RCT has potential to unlock multi-billion-dollar opportunity Technologically differentiated portfolio of high-potential, preclinical assets Multiple programs with clinical

data in both liquid and solid tumors Commercially scaled and validated allogeneic T-cell therapy platform Integrated, proven, pre-commercial manufacturing and R&D platform BLA = Biologics License Application; RCT = Randomized Controlled

Platform Potential to Treat a Wide

Range of EBV-Associated Diseases or Hematological / Solid Tumors Through Engineered CAR or TCR Healthy Donor Cells Minimal HLA matching needed Designed to target root cause of EBV-driven diseases Favorable safety profile Robust manufacturing

process No genetic engineering EBV T-Cell Off-the-Shelf CAR T or TCR T Next-Gen CAR Technologies Retains beneficial features of EBV T-cell CAR-targeted activity and durability Can be modified to express engineered receptors to armor CAR T for

solid tumors EBV-Targeting T-Cell Products: Tab-cel and ATA188 Engineered Oncology Products: Next-gen CAR T or TCR T EBV TCR HLA EBV TCR HLA CAR manufacturing EBV = Epstein-Barr Virus; HLA = Human Leukocyte Antigen; CAR = Chimeric Antigen

Receptor; TCR = T Cell Receptor

Our Vision is to Transcend the

Limitations of Current Cell Therapy by Harnessing the Power of EBV T-cells Autologous Cell Therapy Other Allogeneic Cell Therapy No GvHD but other risks Individually manufactured Long manufacturing time, high COGM, complex logistics Low GvHD but

other risks if need for prolonged lymphodepletion Durable response in PTLD and PMS Favorable safety profile and low GvHD Scale-up potential but unvalidated Variable TCR engineering may contribute to cell exhaustion Preserve "natural

state" cells with adapted phenotype Scaled-up, flexible, off-the-shelf Manufacturing and distribution unproven at scale Proven ability to deliver within 3 days from inventory Limited long-term clinical data Proven only in some heme cancer

Limited Use So Far Complex and Early Optimized and Validated In Clinic Durable Efficacy Tolerability Persistence Scalability Product Supply Patient Access and Experience GvHD = Graft Versus Host Disease; TCR = T Cell Receptor; PMS = Progressive

Multiple Sclerosis; COGM = Cost of Goods Manufactured Complex patient experience with weeks to wait Off-the-shelf Off-the-shelf, convenient, flexible to satisfy patient needs Atara Bio Allogeneic Cell Therapy

Program Indication Target Preclinical

Phase 1 Phase 2 Phase 3 Registration Next Milestone Tab-cel (tabelecleucel) RR EBV+ PTLD following HCT and SOT EBV Q3 2021: Rolling BLA completion Multi-Cohort: EBV+ cancers(1) EBV 2023: Ph2 Study data expected Nasopharyngeal carcinoma(2) EBV

2021: Add'l translational data ATA188 Progressive MS EBV(3) Q1 2021: RCT enrollment and regulatory update ATA2271 Autologous CAR T Solid tumors(4,5,6) Mesothelin Q4 2021: Safety/efficacy data ATA3271 Off-the-shelf, allogeneic CAR T Solid

tumors(4,6) Mesothelin Q2 - Q3 2022: IND filing ATA3219 Off-the-shelf, allogeneic CAR T B-cell malignancies CD19 Q4 2021 - Q1 2022: IND filing Other Programs AML, B-cell malignancies, solid tumors & inf diseases Various Undisclosed Robust T-Cell

Immunotherapy Pipeline These investigational agents are not approved by any regulatory agencies. Efficacy and safety have not been established. EBV+ PTLD: EBV-Associated Post-Transplant Lymphoproliferative Disease; RR: rituximab relapsed/refractory;

HCT: allogeneic hematopoietic cell transplant; SOT: solid organ transplant Other programs: ATA2321 (AML), ATA2431 (B-cell malignancies), and ATA368 (HPV) 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 Phase 1b/2 study in combination with anti-PD-1 therapy, KEYTRUDA (pembrolizumab), in patients with platinum-resistant or recurrent EBV-associated NPC.

Targeted antigen recognition technology; Randomized Controlled Trial 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 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. Worldwide license agreement and research, development and manufacturing collaboration with Bayer to develop Atara's allogeneic off-the-shelf mesothelin CAR T program (ATA3271) and autologous program (ATA2271) ALLELE Study RCT

Dedicated, expandable manufacturing

facility Flexibility to produce multiple T-cell and CAR T immunotherapies Designed to meet global regulatory standards Commercial manufacturing validation activities near completion Robust manufacturing process with data confirming

potential scale up into perfusion bioreactors enabling biologics-like Cost of Goods Manufactured to supply thousands of patients Product being delivered rapidly to patients across three continents from finished product inventory Our Platform is

Nearing Commercial Scale Readiness

Three Strategic Priorities Driving

Long-Term Value Tab-cel ATA188 Next-Gen CAR T BTD program for high unmet need in ultra rare population, with meaningful label expansion potential Compelling efficacy profile in Phase 2 and Phase 3 IA with favorable safety profile Next

Step: Initiate rolling BLA and complete BLA submission in Q3 2021 First-in-Kind Allogeneic T-Cell Therapy Preparing for Historic Regulatory Filing High unmet medical need for the ~1 million progressive MS patients worldwide Clinical data

support potential to halt or reverse disease progression in progressive MS Next Step: Phase 1a OLE data (ongoing), RCT enrollment and regulatory updates (Q1 2021) Transformative MS Treatment in Randomized Controlled Trial (RCT) Urgent need for new

treatment options across solid and liquid tumor indications Portfolio of next-generation CAR T with robust pre-clinical evidence supporting advanced capabilities in solid tumors Next Step: First allogeneic CAR T program IND (Q4 2021 / Q1 2022)

Next-Generation Allogeneic CAR T Programs Leveraging EBV T-Cells IA = Interim AnalysisOLE = Open-label ExtensionBLA = Biologics License Application MS = Multiple SclerosisBTD = Break Through DesignationIND = Investigational New Drug CAR = Chimeric

Antigen ReceptorEBV = Epstein-Barr Virus

Tab-cel (tabelecleucel) ATA188 Update on long-term clinical data from Phase 1a OLE study in an appropriate forum H1 and H2 2021 Present top-line Phase 1 data for mesothelin-targeted autologous CAR T for patients with advanced mesothelioma

Q4 2021 ATA2271 Q3 2021 Complete FDA Biologics License Application (BLA) rolling submission for patients with EBV+ PTLD Q4 2021 Present Phase 3 ALLELE data at an appropriate congress Conduct interim analysis to assess efficacy and safety from Phase

2 randomized, double-blind, placebo-controlled study in patients with progressive forms of MS H1 2022 Submit next-generation off-the-shelf, allogeneic CD-19 targeted CAR T IND for patients with B-cell malignancies Q4 2021 / Q1 2022

ATA3219 Upcoming Key Catalysts Over the Next 24 Months Q4 2021 Submit EU Marketing Authorization Application (MAA) for patients with EBV+ PTLD Complete enrollment of Phase 2 randomized, double-blind, placebo-controlled study in patients with

progressive forms of MS H1 2022 Submit next-generation off-the-shelf, mesothelin-targeted allogeneic CAR T IND for patients with advanced mesothelioma Q2 2022 / Q3 2022 ATA3271 H1 2022 Anticipated U.S. approval of BLA for patients with EBV+ PTLD H2

2022 Anticipated EU approval of MAA for patients with EBV+ PTLD

Atara is Well-Capitalized With

Planned Cash Runway Into 2023 $327.2 million Cash, cash equivalents, and short-term investments as of Sept 30, 2020 $544.2 million Proforma cash, cash equivalents, and short-term investments as of Sept 30, 2020 - including Bayer collaboration

upfront and Dec 7, 2020 follow on offering $74.7 million Q3 2020 Operating Expenses $53.0 million Q3 2020 Net Cash Used in Operating Activities 77.2 million Shares Outstanding as of Sept 30, 2020 * 82.3 million Proforma Shares Outstanding

after Dec 7, 2020 follow on offering ** Nasdaq: ATRA Atara Biotherapeutics, Inc. ** Does not include 7,796,303 of pre-funded common stock warrants * Does not include 5,755,487 of pre-funded common stock warrants includes net offering

proceeds of ~$164M and net proceeds to date from Bayer collaboration of ~$53M

Atara Strategic Priorities to Create

Value: Tab-cel ATA188 CAR T Tab-cel (tabelecleucel) Investigational T-cell immunotherapy for EBV-associated ultra-rare diseases FDA breakthrough designation and EMA PRIME for EBV+ PTLD

Virus-EBV-Causes Rare and Serious Cancers In Patients With Impaired Immune Function EBV is a common driver of IA-LPDs EBV is a ubiquitous yet typically dormant virus Once infected, healthy patients harbor lifelong infection that is

usually kept in check by their immune systems In patients with impaired immune function, uncontrolled growth of EBV-infected cells can lead to lymphomas (IA-LPDs) Such EBV-driven cancers have no approved therapies and poor prognosis with

limited life expectancy for patients Patients with impaired immune function include those who have: Conditions requiring immunosuppressive medication (e.g. post-transplant patients, patients with serious autoimmune diseases)

Diseases that lower immunity (e.g. HIV) Inborn genetic immune deficiency (e.g. PIDs) EBV: Epstein Barr virus; IA-LPDs: Immunodeficiency-associated lymphoproliferative disorders; PIDs: Primary immunodeficiencies AID = acquired immunodeficiency PID =

primary immunodeficiency Phase 2 multicohort study populations include: AID-LPD; PID-LPD; 1L treatment inappropriate PTLD; CNS PTLD; sarcoma, including LMS; viremia with HLH Ph 3 ALLELE study in previously treated EBV+ PTLD Phase 2 multicohort study

underway covering six additional patient populations, with aim to expand tab-cel's label Tab-cel specifically targets and kills EBV-infected cells, addressing disease at the source Tab-cel has the potential to transform the lives of

thousands of patients each year

EBV-Associated Post-Transplant

Lymphoproliferative Disease Aggressive, Often Deadly Cancer with No Approved Therapy Average age under 40 years vs. around 65 years for NHL Bone marrow transplant (HCT) EBV+ PTLD risk up to recovery of immune system (~1 year) Solid organ transplant

(SOT) Chronic risk of PTLD from immunosuppression; Highest risk within ~1 year of transplant(1) High mortality in rituximab chemo relapsed/refractory patients Median survival HCT: 1.7 months(2) SOT: 3.3 months(3) Rare B-cell lymphoma that

occurs in immunosuppressed patients after transplant NHL: Non-Hodgkin Lymphoma Dierickx D, Habermann TM. N Engl J Med. 2018 Feb 8;378(6):549-562. Soci , G. et al. In: Proceedings of the 46th Annual Meeting of the European Society for Blood and

Marrow Transplantation; 2020 Aug 30-Sep 2; Virtual. EBMT 2020; Abstract B208 Zimmermann, H. et al. Presented at the 24th Congress of European Hematology Association; 2019 June 13; Amsterdam, The Netherlands. EHA 2019; Poster Ayden PTLD

Outcomes for Patients with EBV+ PTLD in Phase 2 and EAP Studies(1,2) Few treatment-related serious adverse events (SAEs): 12 possibly related Serious Adverse Events (SAEs) among 173 patients: no infusion related toxicities, no CRS (cytokine release

syndrome) and three possibly related graft vs. host disease (GvHD); Safety data on file as of December 2017. NCT00002663 and NCT01498484; Prockop, S., et al. EHA 2018. Prockop, S., et al. Abstract 4071, ASH 2019. In a subgroup of 22 patients who

would have likely met eligibility criteria for Atara's ongoing tab-cel Phase 3 studies Phase 2 SOT Phase 2 HCT All, n=14, 1-yr OS=64.3% Non Response, n=7, 1-yr OS=28.6% Response, n=7, (2CRs, 5PRs) 1-yr OS=100% 14 (0) 7 (7) 9 (5) 9 (5) 7

(7) 6 (8) 6 (8) 6 (8) 4 (8) 4 (8) 2 (9) 7 (0) 1 (6) 2 (5) 2 (5) 1 (6) 1 (6) 1 (6) 1 (6) 1 (6) 1 (6) 0 (7) 7 (0) 6 (1) 7 (0) 7 (0) 6 (1) 5 (2) 5 (2) 5 (2) 3 (2) 3 (2) 2 (2) Overall Survival Time (Months) Median + Censored Number at Risk (Event): All

Non Response Response 0 6 12 18 24 30 36 42 48 54 60 0.0 0.6 0.8 0.4 0.2 1.0 Probability of Survival Probability of Survival 0 6 12 18 24 30 36 42 48 54 60 Number at Risk (Event): 35 (0) 18 (14) 23 (11) 26 (9) 17 (14) 14 (14) 13 (15) 12 (15) 6 (15)

3 (15) 3 (15) All 11 (0) 0 (10) 2 (8) 4 (7) Non Response 24 (0) 18 (4) 21 (3) 22 (2) 17 (4) 14 (4) 13 (5) 12 (5) 6 (5) 3 (5) 3 (5) Response + Censored Median All, n=35, 1-yr OS=68.3% Non Response, n=11, 1-yr OS=24.2% Response, n=24, (20CRs, 4PRs)

1-yr OS=87.5% Overall Survival Time (Months) 0.0 0.6 0.8 0.4 0.2 1.0 Phase 2 overall survival at 2 years in responders 83% EAP overall survival at 2 years for all patients(3) 79% Phase 2 overall survival at 2 years in responders 86% EAP overall

survival at 2 years for all patients(3) 81%

Tab-cel Achieved 50% Objective

Response Rate in Pivotal Phase 3 Study Interim Analysis by Independent Oncologic and Radiographic Assessment 50% N = 35 N = 14 HCT SOT 69% 82% 55% N = 11 N = 11 EAP EAP Phase 2 Phase 2 Investigator Assessed: Phase 2 and EAP ORR for EBV+ PTLD