Investor presentation 42nd Annual j.p. morgan healthcare conference monday, January 8, 2024 Nasdaq: ATRA Exhibit 99.1

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First Company to Obtain Regulatory Approval for an Allogeneic T-cell Immunotherapy EbvalloTM Approved by EMA in December 2022; BLA submission expected in Q2 2024 Expanded global tab-cel® partnership with Pierre Fabre closed in December 2023 Near-Term Milestones with ATA3219, Allogeneic CD19 CAR T Cell Incorporating Clinically-Validated Technologies Lupus nephritis IND filing anticipated Q1 2024 IND cleared in relapsed/refractory B-cell NHL with initial clinical data anticipated H2 2024  Focused Operational Activities and Associated Strategic Restructuring Extends Cash Runway into 2027 ATARA IS THE FIRST TO DELIVER ON THE TRANSFORMATIVE POTENTIAL OF ALLOGENEIC T-CELL THERAPY

Expanded Global Tab-cel® Partnership with Pierre Fabre Laboratories Closed in December 2023 Pierre Fabre Laboratories license for tab-cel global development, manufacturing and commercialization, with up to $640 million in potential consideration and significant double-digit tiered royalties Pierre Fabre Laboratories to reimburse Atara for tab-cel global development costs through BLA approval, and purchase current and future tab-cel inventory through BLA transfer Substantially all tab-cel® clinical, regulatory and manufacturing activities planned to transfer to Pierre Fabre Laboratories at time of BLA transfer Atara received ~$27 million in upfront cash and initial inventory purchases at closing (Dec 2023), and will receive additional $100 million in potential regulatory milestones through BLA approval Partnership will expand reach of tab-cel’s life-saving potential to patients worldwide and provide future revenues for Atara

Tab-cel BLA Submission on Track for Q2 2024 Based on Strong Clinical File Latest Phase 3 ALLELE data cut analysis reinforces confidence in tab-cel BLA filing package 49% ORR (p<0.0001) in patient population aligned with intended U.S. label Favorable and consistent safety profile Other findings consistent with previous results, including DOR and estimated OS Separate pooled analysis including patients from ongoing tab-cel multicohort EBVision trial presented at ESMO-IO1 77.8% ORR in 18 EBV+ CNS PTLD patients, including first line PTLD setting Long-term survival, and favorable and consistent safety profile 1Annals of Oncology (2023) 20 (suppl_1): 100520-100520. 10.1016/iotech/iotech100520 ORR – Objective Response Rate; DOR – Durability of Response; OS – Overall Survival

Allogeneic EBV T-Cell Next-gen Allogeneic CAR T The Only Allogeneic T-cell Platform With an Approved Product Designed to target root cause of EBV-driven diseases No gene editing of the TCR Minimal HLA matching required Favorable safety profile Robust manufacturing process Retains beneficial features of EBV T-cell with no gene editing of TCR CAR-targeted activity and can be modified to express dual targets and/or engineered to armor CAR T Leverages novel CD3ζ signaling domain (1XX) with more physiologic levels of T-cell signaling EBV T Cell CAR T Chimeric Antigen Receptor EBV TCR EBV TCR CAR Manufacturing Viral Vector Healthy Donor Cells EBV = Epstein-Barr Virus; HLA = Human Leukocyte Antigen; CAR = Chimeric Antigen Receptor; TCR = T-cell Receptor Tab-cell® (EbvalloTM) is only approved in the European Union

Strategic Focus on Allogeneic CAR T Programs for Heme Malignancies and Various Autoimmune Conditions Develop best-in-class allogeneic programs for NHL and B-cell malignancies Establish promise of allogeneic CAR T across autoimmune diseases, starting in Lupus Nephritis ` ` Hematological Malignancies B-cell Driven Autoimmune Disease Hematological Malignancies B-cell Driven Autoimmune Diseases ATA3219  CD19 CAR – IND Cleared in NHL and IND for Lupus in Q1’24 ATA3431 CD19 / 20 CAR – IND-enabling studies

Other Allogeneic CAR Platforms Atara’s Allogeneic CAR T Platform is Differentiated and has Potential to be Best-in-Class CAR Αβ T (gene-edited) CAR-NK CAR γδ Safety Safer than auto CAR T  Some require high and prolonged lymphodepletion Expansion Moderate Minimal; high dose needed Minimal Persistence ~3-4 weeks < 3 weeks Suboptimal Durability Moderate Suboptimal Suboptimal Other Allogeneic CAR T Platforms ScFv EBV TCR MHC Persistence: Endogenous TCR Expansion and persistence: 1XX, no genetic editing or stealth approaches Safety: Minimal HLA matching Objective is to deliver deep and durable clinical responses with a well-tolerated product profile Atara’s CAR Platform Durability: Less differentiated phenotype of unedited T cells Novel 1XX costimulatory domain Atara’s Allogeneic CAR T Platform Αβ – alpha beta; NK = natural killer; γδ – gamma delta

1. Park, JH et al. Poster 163A. ASH 2022. 2. Curran KJ, et al. ASH 2023. 3. Barba, P et al. Poster 439. ASH 2022. 9 Clinical Validation From Industry Leaders  Substantiates Key Attributes of Our Allogeneic CAR T Platform TAK-940 CD19 auto CAR T with 1XX Dose level 1 (25M) resulted in ORR 89%, CR 78% (n=9)1 Memorial Sloan Kettering Allogeneic EBV CD19 CAR T  Overall survival up to 3 years in post-transplant patients2 YTB323 Stem-enriched auto CD19 CAR T 69% durable CRs at 6 months (DL2 – 12.5M, n=30)3 1 2 3 Less differentiated T Cells Durability 1XX signaling domain Expansion and persistence Endogenous TCR & minimal HLA matching Persistence and safety

Our Allogeneic CAR T Cell Programs Incorporates Clinically Validated Technologies Target: CD19+ B-cell malignancies, Autoimmune Target: CD19/CD20+ B-cell malignancies, Autoimmune EBV TCR Partially Matched MHC Novel 1XX costimulatory domain Novel 1XX costimulatory domain Partially Matched MHC EBV TCR CD19 ScFv CD19/CD20 ScFv ATA3219 (CD19 CAR) ATA3431 (CD19 / 20 CAR)

Access challenges for auto CAR T Only ~10-20% of DLBCL patients receive autologous CD19 CAR T today, despite being eligible1,2 Durability challenges for auto CAR T Only ~30-40% of those who receive autologous CD19 CAR T therapy have durable response at 6 months3† 10-20% 30-40% ~15,000 CD19 CAR T-cell addressable patients in 2L+ DLBCL in U.S.1,2 12023 ClarivateTM, 2GlobalData, 3Atallah-Yunes, SA, et al. (2022). Note: Estimates for 2022 do not include full impact of ongoing 2nd Line CAR T utilization. †Estimate derived from PIs of approved auto CART; includes reported and extrapolated information. RHS – press searches ATA3219 in NHL: Opportunity To Compete With a Differentiated Profile Given Limitations With Other CD19-Targeted Therapies Durability and persistence challenges for allogeneic CD19 CAR cell therapy Efficacy and safety challenges for bispecifics Products entering the market, however questions on level of adoption given risk/benefit profile Unmet Need Despite Approved Auto CAR T Bispecifics & Allo CAR T Yet to Deliver Limited durability of remission with no clinically superior  platform

ATA3219 pre-clinical data demonstrated long-term in vivo expansion, polyfunctional phenotype, and efficient targeting of CD19 expressing tumor cells with low alloreactivity5 ATA3219 in NHL: IND Cleared and Phase 1 Study Commencing for Atara's First Allogeneic CAR T   1. Park, JH et al. Poster 163A. ASH 2022. 2. Stenger D, et al. Blood 2020. 3. Barba, P et al. Poster 439. ASH 2022. 4. Shahid, S et al. Poster presented at ASH; 2023. 5. Pham, C, et all. Abstract presented at Transplantation & Cellular Therapy (TCT) Meetings; 2023. Less differentiated T- cell phenotype clinically correlated to improved and durable clinical responses3 1XX signaling domain associated with favorable response rates, durability, and safety1 Retention of the well-defined, endogenous TCR, essential for the longevity of the response2 Proof-of-principle: An academic clinical study of an earlier-generation allogeneic CD19 targeted CAR EBV T-cell construct showed overall survival of up to three years in 12 patients with relapsed/refractory B-cell malignancies after hematopoietic cell transplant4 2 1 3 Novel 1XX costimulatory domain EBV TCR CD19 ScFv Partially Matched MHC 2 1 3 ATA3219: Next-generation off-the-shelf, allogeneic CD19-1XX CAR+ EBV T cell incorporates multiple clinically-validated technologies

ATA3219 in NHL: Potential "Best-in-Class" Profile as Pre-Clinical Data Supports Superior Persistence and Anti-Tumor Efficacy  Pham, C, et al. Abstract presented at Transplantation & Cellular Therapy (TCT) Meetings; 2023 Note: T-cell infusion on day 3 day after tumor implantation (day 0); infusion timepoint represented as a vertical line on the center graph. Less differentiated T Cells for ATA3219 Longer persistence in tumor model versus auto CD19 CAR benchmark1 Superior anti-tumor efficacy versus auto CD19 CAR benchmark1 Nalm6 model ATA3219 Auto Benchmark PBS NTD Days post-tumor implantation Percent survival 0 1 0 2 0 3 0 4 0 5 0 6 0 0 5 0 10 0 VCN normalized to input Auto CD19 CAR Benchmark ATA3219 Percent survival CCR7 CD45RO Nalm6 model

Timeline Planned IND in Lupus Nephritis in Q1’ 24 ATA3219 in Autoimmune: In a Field With Growing Momentum, Atara is Rapidly Advancing in Lupus Nephritis Unmet Need High unmet medical need in Lupus Nephritis; standard of care and approved products have limited efficacy Proof of Concept Compelling validation from autologous CAR T academic study (8/8 patients with >1 year post CAR T cell infusion attaining remission in Lupus1) and emerging industry data  Novel Approach No B-cell targeted allogeneic product clinical data in Lupus or autoimmune disease yet  Rationale for CD19 CAR T in Lupus Nephritis ATA3219 is Well Positioned Efficacy Robust and specific B cell depletion in Lupus model, with associated cytokine response Less differentiated phenotype and 1XX drive cellular fitness Potential to enable rapid & deep B-cell depletion Safety Limited non-specific activity in Lupus model No gene editing required – significant safety experience in more than 500 patients across diseases with allogeneic EBV T cells 1XX designed to be less inflammatory Numerous other autoimmune conditions could potentially benefit from ATA3219  1. Blood (2023) 142 (Supplement 1): 220.

ATA3431: Off-the-Shelf Allogeneic CD19/CD20 CAR T Program Progressing With IND-Enabling Studies Positive preclinical data presented at American Society of Hematology meeting in December 20231 Targeting CD19 and CD20 reduces probability of relapse due to CD19 antigen loss, hypothesized to be a major cause of treatment resistance or disease relapse after CD19 CAR T treatment Targeting CD19 and CD20 provides potential incremental efficacy benefit and 1XX co-stimulation for enhanced persistence Autologous CD19/CD20 dual CAR T has shown promising efficacy and safety in clinical trials (IMPT-314) ATA3431 preclinical data demonstrates a competitive profile based on potent antitumor activity, long-term persistence, and superior tumor growth inhibition EBV TCR Partially Matched MHC Novel 1XX costimulatory domain CD19/CD20 ScFv Cha, S et al. Poster 4800. ATA3431: Allogeneic CD19/CD20 Bispecific CAR EBV T Cells for the Treatment of B-Cell Malignancies. ASH 2023.

ATA3431: Compelling Proof-of-Concept and Competitive Profile Challenging CD19low / CD20+ Raji model ATA3431 advancing into IND-enabling studies Greater Anti-Tumor Efficacy vs CD19/CD20 Autologous Benchmark Cha, S et al. Poster 4800. ATA3431: Allogeneic CD19/CD20 Bispecific CAR EBV T Cells for the Treatment of B-Cell Malignancies. ASH 2023.

Differentiated Allogeneic T-Cell Immunotherapy Pipeline 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-Associated Post-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 Phase 2 multi-cohort initiated in Q3 2020, with possible indications including EBV+ PTLD with CNS involvement, EBV+ PID/AID LPD, and other potential EBV-associated diseases Targeted antigen recognition technology; Phase 2 Randomized Controlled Trial Program Indication Target Preclinical Phase 1 Phase 2 Phase 3 Registration Next Milestone Tab-cel® or EbvalloTM (tabelecleucel) RR EBV+ PTLD following HCT and SOT EBV Q2 2024: BLA submission expected Multi-Cohort (Label-Expansion): EBV+ cancers(1) EBV Ongoing enrollment ATA3219 (Allogeneic) B-cell malignancies, including NHL CD19 H2 2024: Preliminary NHL Phase 1 clinical data expected Autoimmune disease, including Lupus Nephritis Q1 2024: planned IND submission ATA3431 (Allogeneic) B-cell malignancies CD19/CD20 Advancing into IND-enabling studies Autoimmune disease ATA188 Progressive MS EBV(2) Evaluating strategic options EMBOLD Study EBVision Study EU Approved ALLELE Study

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