#1ތކތކޓރކFކށީނނި ހކއކކޗރޓަހކރކ1 ބދށަގނޑއ ހކރރއހރއނދއނަ އނ އދގެ އދއޖހވރވ ކމއ ދހހހހހށަހދއށައވރވއދއތ ތ، މ.އއާ ނ ހރ ހހހހހހ. non Conditionally Active Biologics: Transforming Cancer Therapy Corporate Presentation May 2023 bicatla#2Important Notices & Disclaimers This presentation (the "Presentation") by BioAtla, Inc. ("we", "us", "our", "BioAtla", or the "Company") contains "forward-looking statements" within the meaning of the Private Securities Litigation Reform Act of 1995 relating to our business, operations and financial conditions, including but not limited to current beliefs, expectations and assumptions regarding the future of our business, future plans and strategies, results of clinical trials and other future conditions. Words such as, but not limited to, "anticipate", "believe", "could", "estimate", "expect", "intend", "may", "plan", "potential", "predict", "project", "should", "will", "would" or the negative of those terms, and similar expressions that convey uncertainty of future events or outcomes, identify forward-looking statements. These forward-looking statements reflect management's beliefs and views with respect to future events and are based on estimates and assumptions as of the date of this Presentation and are subject to risks and uncertainties, including those described in the Company's filings with the SEC, including but not limited to the Company's latest Quarterly Report on Form 10-Q. Moreover, the Company operates in a very competitive and rapidly changing environment. New risks emerge from time to time. It is not possible for management to predict all risks, nor can the Company assess the impact of all factors on its business or the extent to which any factor, or combination of factors, may cause actual results to differ materially from those contained in any forward-looking statements we may make. Given these uncertainties, you should not place undue reliance on these forward-looking statements. The Company qualifies all the forward-looking statements in this Presentation by these cautionary statements. Except as required by law, the Company undertakes no obligation to publicly update any forward-looking statements, whether as a result of new information, future events or otherwise. Statements contained herein are made as of the date of this Presentation unless stated otherwise, and this Presentation shall not under any circumstances create an implication that the information contained herein is correct as of any time after such date or that the information will be updated or revisited to reflect information that subsequently becomes available or changes occurring after that date hereof. Certain information contained in this Presentation relates to or is based on statistical and other industry and market data obtained from independent industry publications and research, surveys and studies conducted by independent third parties as well as the Company's own estimates of the prevalence of certain diseases and conditions. The market data used in this Presentation involves a number of assumptions and limitations, and you are cautioned not to give undue weight to such data. Industry publications and third-party research, surveys and studies generally indicate that their information has been obtained from sources believed to be reliable, although they do not guarantee the accuracy or completeness of such information. The Company's estimates of the patient population with the potential to benefit from treatment with any product candidates the Company may develop include several key assumptions based on its industry knowledge, industry publications and third-party research, which may be based on a small sample size and may fail to accurately reflect the addressable patient population. While the Company believes that its internal assumptions are reasonable, no independent source has verified such assumptions. This Presentation may contain trademarks, trade names, or service marks belonging to other entities. The Company does not intend the use or display of other parties' trade names, trademarks or service marks to imply a relationship with, or endorsement or sponsorship of, or by these other parties. None of the Company or any of its directors, officers, employees, contractors, agents, consultants, advisors or other representatives makes any representation or warranty, express or implied, as to the accuracy or completeness of the information contained in this Presentation. bicatla BioAtla| Overview 2#3BioAtla® is a clinical stage company focused on transforming cancer therapy with Conditionally Active Biologics (CABS) Proprietary technology Broad applicability in solid tumors Increases therapeutic bicatla window Two Phase 2 CAB-ADCs, one Phase 1 CAB-I/O and one Phase 1 CAB-bispecific T-cell engager BA3011 advancing potentially registrational studies in sarcoma and NSCLC Diversified pipeline Clinical readouts for multiple indications through 2023 Strategic optionality Strong cash position $192.7 million in cash and cash equivalents as of 03/31/23 Sufficient through key clinical milestones into 2025 BioAtla| Overview 3#4Leadership Team Jay Short, Ph.D. Chairman, CEO and Cofounder STRATAGENE DIVERSA HARNESSING THE POWER OF ENZYMES bicatla life technologies Richard Waldron, M.B.A. Chief Financial Officer SYNTHETIC GENOMICS INTREXON GeneMedicine, Inc. COWEN Cathy Chang, Ph.D. Sr. VP, Research & Development DIVERSA HARNESSING THE POWER OF ENZYMES STRATAGENE AND COMPANY Philippe Martin, M.S., M.B.A. Chief of Clinical Dev & Operations Colame Aventis op Schering-Plough Celgene William Boyle, Ph.D. Sr. Research Fellow Anaptys Bio AMGEN salk Where cures begin. Sheri Lydick Sr. VP, Commercial Strategy STRATAGENE Celgenel Bristol Myers Squibb ALTANA Monica Sullivan Sr. VP, Intellectual Property & Contracts DIVERSA BARNESSING THE POWER OF ENZYMES CapalP senomyx Eric Sievers, M.D. Chief Medical Officer OSeattleGenetics ZYMOGENETICS A Bristol-Myers Squibb Company Susie Melody Sr. VP, Human Resources Biogen. BCG BioAtla| Overview FRED HUTCH CURES START HERE 4#5Board of Directors' and Advisors bicatla Jay Short, Ph.D. Chairman, Chief Executive Officer & Cofounder Board of Director Scott Smith Board of Director James Allison, Ph.D. MD Anderson Cancer Center Scientific Advisor Mary Ann Gray, Ph.D. Board of Director Lawrence Steinman, MD Board of Director Padmanee Sharma, MD, Ph.D. MD Anderson Cancer Center Scientific Advisor Sylvia McBrinn Board of Director Lawrence Fong, MD Cancer Immunotherapy Program, UCSF Scientific Advisor Susan Moran, MD, MSCE Board of Director Eddie Williams Board of Director Michael Manyak, MD GlaxoSmithKline Scientific Advisor BioAtla| Overview 5#6Selective and targeted CAB technology widens therapeutic window, thus has the potential to enhance clinical outcomes in multiple tumor types సం bicatla BioAtla discovered that acidic pH at the cancer cell surface unveils binding sites that are shielded at normal pH of healthy cells BioAtla invented CAB technology, creating antibodies that bind only to these unveiled sites on cancer cells CAB binding region is not masked or caged and thus different from prodrugs that require irreversible enzymatic cleavage to become activated CAB antibodies have the potential for increased efficacy with improved safety relative to traditional antibodies Alkaline Healthy Cell Membrane Glycocalyx Basic pH BARZO 2 HEALTHY CELL Intracellular Mildly Acidic pH No CAB Binding H H REMENSE Acidic Cancer Cell Membrane CANCER CELL Intracellular Mildly Basic pH CAB Binding H+ H H H H Glycocalyx Acidic pH H H Chang, H.W., Frey, G., Liu, H., Xing, C., Steinman, L, Boyle, B.J., & Short, J.M. (2021) PNAS 118(9): 1-10, Suppl. 1-19. BioAtla| Overview 6#7Broad applicability of BioAtla's CAB platform across several antibody types has the potential to treat multiple solid tumors Targets: AXL, ROR2 ADCs Widely expressed in a variety of tumor types, AXL and ROR2 overexpression correlates with poor prognosis, metastasis, and drug resistance to PD-1 and EGFR therapies CAB-Tumor Cell Target bicatla Cytotoxic payload and linker Naked Antibodies I/O ADC - antibody drug conjugate; 10 - immuno-oncology; TCE - T-cell engager Target: CTLA-4 CTLA-4 blockade activates effector T cells, thereby enhancing anti- tumor immunity CAB-CTLA4 CAB-CTLA4 Bispecific TCE Target: EpCAM & CD3 Bispecific antibodies bridge cancer cells and cytotoxic T lymphocytes, activating T cells and promoting cancer cell lysis Tumor Cell Target T Cell Target CAB-EPCAM CAB-CD3 BioAtla| Overview 7#8Focused pipeline with broad applicability of differentiated CAB assets designed to deliver near-term value CAB-ADCs Bispe CAB- CAB- cific TCE O/I CAB CAB Program BA3011 Mecbotamab Vedotin BA3021 Ozuriftamab Vedotin BA3071 BA3182 Additional programs bicatla Target AXL ROR2 CTLA-4 EpCAM x CD3 Various Indications STS & Bone Sarcoma NSCLC Ovarian Cancer* NSCLC SCCHN Melanoma Ovarian Cancer* Multiple tumor types** Adenocarcinoma** Multiple tumor types** Multiple tumor types** IND Enabling Pre-Clinical Phase 1 Clinical IIT, investigator-initiated trial; IND, investigational new drug; NSCLC, Non-small Cell Lung Cancer; SCCHN, Squamous Cell Carcinoma of the Head and Neck; STS, Soft Tissue Sarcoma; FPI, First Patient In. Phase 2 Clinical Anticipated Milestones ● ✓ Initiated UPS Phase 2, part 2 potentially registrational study (1H) ● ● Submitted Exposure-Response analysis to medical meeting (1H) Enrolling more frequent dosing regimens in NSCLC as part of Phase 2, part 1 (1H) ● Request FDA feedback re: Phase 2, part 2 NSCLC potentially registrational study design (1H) Receive FDA feedback re: Phase 2, part 2 NSCLC (2H) Initiate Phase 2, part 2 NSCLC potentially registrational study (2H) Phase 2 IIT interim data ovarian (2H) ✓ FPI SCCHN Phase 2 (1H) Initiated NSCLC Phase 2 more frequent, dose intensive regimens (1H) Prioritize registration indications (2H) Phase 2 IIT interim data ovarian (2H) Phase 1 data (2H) Initiate Phase 2 (2H) ✓ Phase 1 IND clearance (1H) ✓ Initiate Phase 1 (1H) Additional INDS, 2023 / 2024 *Phase 2 investigator-initiated trial for Ovarian Cancer ** Indications based upon tumor target expression BioAtla| Overview 8#9bicatla CAB-AXL-ADC Platform BA3011 Mecbotamab Vedotin: Sarcoma and NSCLC#10Potential market opportunity in sarcoma 2nd most common Soft Tissue Sarcoma (STS) subtype (~15% of all STS)¹ UPS Other Subtypes bicatla 1 2 3 High-grade aggressive subtype with high recurrence rates¹ 3k 4k AXL+ addressable patients per year in the U.S.1,2 - - Current Treatments Chemotherapy, chemoradiation or regional limb therapy for unresectable cases No approved therapies specifically for UPS Approved treatments for sarcoma ORR ~15%³ 1 Osteosarcoma - most common malignant primary bone tumor (30% of all such malignancies)4 2 Liposarcoma - one of the largest soft tissue sarcoma subtypes (15% - 20% of all STS)5 3 Synovial sarcoma - smaller subtype, but high recurrence rate (~50% of patients) 4 Limited effective treatment options across all sarcoma subtypes ¹Undifferentiated Pleomorphic Sarcoma - StatPearls - NCBI Bookshelf (nih.gov); Annals of Oncology 30: 1143-1153, 2019; ²Company estimates; ³Product USPIs; 4https://www.cancernetwork.com/view/bone-sarcomas. 5https://rarediseases.org/rare-diseases/liposarcoma/; "https://www.sciencedirect.com/science/article/pii/S0923753419386727 ORR, objective response rate (best objective response as confirmed complete response or partial response); STS, soft tissue sarcoma; UPS, undifferentiated pleomorphic sarcoma. BioAtla| Overview 10#11Encouraging Phase 1 results with Mecbotamab Vedotin (BA3011) in refractory sarcoma ■ Confirmed TmPS* ≥70; 1.8mg/kg Q3W or 2Q3W Maximum % Change from Baseline in Sum of Target Lesions 100 80 60 40 20 -20 -40 -60 -80 -100 AXL+ TmPS-90$ bicatla 1.8mg/kg d1,8 Leiomyosarcoma (LMS) AXL+ TmPS=100 1.8mg/kg d1,8 Synovial² Sarcoma AXL+ TmPS=100 1.8mg/kg d1,8 Uterine LMS r Confirmed Partial Response (PR) AXL+ TmPS-90 1.8mg/kg LMS * (NED¹) AXL+ TmPS-95 1.8mg/kg d1,8 UPS AXL+ TmPS-70 1.8mg/kg d1,8 UPS AXL+ TmPS=100 1.8mg/kg Ewing I Change in Target Lesion from Baseline (%) Evaluable Patients in Phase 1 at All Doses 100 80 60 40 20 -20 -40 -60 -80 -100 0 10 All patients: Multiple cycles of antineoplastic agents received prior to starting treatment with BA3011 *AXL Tumor membrane Percent Score or TmPS = % Score 21+; $Tissue biopsy from resection, over 1 year old prior to trial entry ¹NED = No evidence of disease; 2Synovial sarcoma patient delayed treatment due to unrelated SAE led to progression 20 = 30 High TmPS ≥70 Low TmPS ≤70 or Not Evaluable PR was achieved in 4/7 high TmPS patients receiving the clinically-meaningful 1.8 mg/kg dose Q3W and 2Q3W Antitumor activity correlates with higher levels of AXL tumor membrane expression in sarcoma patients 40 Time (weeks) 50 60 70 BioAtla| Overview 11#12Undifferentiated Pleomorphic Sarcoma (UPS): ORR 50%, Median PFS 10.9 months Phase 1 & Phase 2, part 1 change in target lesion and progression free survival (1.8mg/kg; n=10) % Change in Target Lesions 80 ■ 60 40 20 0 -20 -40 -60 -80 -100 O 10 Change Target Lesion From Baseline (%) 20 30 50 40 Time (Weeks) Combined Phase 1 & 2: efficacy evaluable = 10 TmPS ≥ 50% 60 70 80 90 5/10 patients achieved PRs, with an ORR of 50% and PFS rate at 3 months of 60% Responses to BA3011 treatment are durable, with DOR currently exceeding 8 months Interim results satisfied the pre-defined Go criteria of UPS cohort into part 2 of the Phase 2 study Average prior lines of systemic therapy = 3 bicatla ■ ■ Progress-Free Survival Probability 1.0 0.8 0.6 - 0.4- 0.2 0.0 T 0 1 1 T T 2 3 Number at Risk All Patients 10 10 8 4 4 4 Progression-free Survival All Patients 5 6 T T 7 8 Events n(%) 6 (60.0) Median (mos) (95% CI) 10.9 (1.4 - NE) T T T T 9 10 11 12 13 14 15 Months from First Dose 4 4 3 3 3 3 2 2 2 2 1 Interim data- Data cut-off of Jan 18, 2023 *Votrient package insert, accessed March 2023. **DOI: 10.1200/JCO.2019.37.15_suppl. 11015 Journal of Clinical Oncology 37, no. 15_suppl (May 20, 2019) 11015-11015. TmPS, tumor membrane percent score; ORR, objective response rate; PFS, progression free survival; DOR, duration of response. 16 PFS 3mo % (95% CI) 60.0 (18.4, 75.3) T T T T T 17 18 19 20 21 22 23 24 1 1 1 1 1 1 10 Phase 3 randomized study of pazopanib versus placebo in metastatic soft-tissue sarcoma ("other" cohort that included UPS), progressing despite previous chemotherapy, reported a median PFS of 4.6 months for pazopanib and 1.0 months for placebo.* Single-arm SARC028 study of pembrolizumab in advanced UPS, reported median PFS of 3.0 months** Limitations of cross trial comparison should be taken into account when comparing studies BioAtla| Overview 12#13Sarcoma update • Initiated UPS Phase 2, part 2 potentially registrational study Based on safety and exposure-response of our CAB-ADCs, we believe that we can further maximize benefit while maintaining an acceptable and differentiated safety profile with more frequent dosing Enrolling total of ~80 AXL-expressing UPS patients in Phase 2, part 2 o FDA supportive of investigating a more frequent dosing regimen (3Q4W 44% and 2Q3W 38% increased exposure over Q2W) o First 40 patients with a TmPS >=50% will be randomized 1:1 to 3Q4W or 2Q3W dosing regimen o Additional 40 patients will be enrolled at the selected dose Primary efficacy endpoint is objective response rate (ORR) per RECIST v1.1 o Primary efficacy analysis will be based on ~60 patients treated at the selected dosing regimen - Prior systemic regimens limited to <3 Currently studying 3Q4W dosing regimen in LMS / UPS Phase 2, part 1 cohorts (combined n = ~10-15) First 6 patients cleared DLT period using the more frequent dosing (3Q4W) - completed Q1'23 bicatla UPS = Undifferentiated Pleomorphic Sarcoma; LMS = Leiomyosarcoma BioAtla| Overview 13#14Phase 2, part 1 topline interim analysis results confirm Phase 1 signal following BA3011 in refractory sarcoma subtypes BA3011 Monotherapy (n=78) Combination with PD-1 (n=26) bicatla Phase 2, Part 1 STS Bone CD20 (BA3011 + Opdivo) Leiomyosarcoma (n=19)* Synovial sarcoma (n=5)* Liposarcoma (n=8)* Other Soft Tissue / UPS (n=18/8)* Osteosarcoma (n=8)* Ewing sarcoma (n=9)* Others (chondro/chordo) (n=11 [6/ 3])* CD 20 Positive (n=14)* CD 20 Negative (n=12)* Interim Results Leiomyosarcoma; Enrolling 3Q4W Synovial PFS rate 12W 54% Liposarcoma PFS rate 12W 67% UPS Enrolling 3Q4W Osteosarcoma; PFS rate 12W 67% Ewing sarcoma Pending Others (chondro/chordo) Pending Combo w/ PD-1; PR = 1/1 (UPS)** & PFS rate 12W (combo overall) 32% Combo w/ PD-1, 1 PR (LMS); PFS rate 12W 31% Cohorts in gray continue to interim read-out Advance Phase 2, Part 2 Evaluating Go - Label Expansion Go - Label Expansion Go - Initial Indication Go - Label Expansion 1 Not advancing Not advancing Interim results satisfied pre-defined 'Go' criteria into part 2 of the Phase 2 BA3011 study in multiple sarcoma subtypes: UPS - clear guidance from FDA, enrolling phase 2, part 2 as initial indication Osteosarcoma, liposarcoma and synovial - pursue registration post UPS approval Pre-defined criteria for each subgroup up to 10 patients: 'No Go' if 0 CR/PR and PFS rate at 3 months <40%; 'Go' if ≥1 CR/PR or PFS rate at 3 months >40%. * enrollment as of Feb 28, 2022; Cohorts in gray continuing enrollment until sufficient sample size is achieved. **Included in UPS cohort. BA3011 dose 1.8 mg/kg Q2W. PFS, progression-free survival; PR, partial response; UPS, undifferentiated pleomorphic sarcoma. BioAtla| Overview 14#15Continued promising safety and tolerability profile in sarcoma Phase 2 at the RP2D 1.8 mg/kg Q2W Characteristic Any Adverse Events (AES) Related AEs with CTCAE¹ Grade 3 or 4² Any related serious AEs² Related AEs leading to death² Related AEs leading to treatment discontinuation² bicatla Constipation Peripheral Neuropathy BA3011 (N=73) 69 (94%) 20 (27%) 5 (7%) Diarrhea 0 4 (5%) BA3011 + Opdivo (N=26) 24 (92%) 10 (39%) 5 (19%) 0 Grade 1-2 (21%) Grade 3 (1%) All Grade 1-2 (16%) 1 (4%)^ Grade 3-4 (0%) Grade 1-2 (16%) Grade 3-4 (0%) Low-grade constipation observed is consistent with baseline levels seen in advanced cancer patients ■ ■ I No treatment-related deaths Few treatment-related SAESs, consistent with MMAE-based toxicity, including reversible myelosuppression, transient liver enzyme elevation, metabolic disturbances Very few related AEs leading to treatment discontinuation No clinically meaningful on-target toxicity observed over background Differentiated profile due to avoiding on-target off-tumor toxicity Interim data- Data cut-off of Jan 18, 2023 1CTCAE: Common Terminology Criteria for Adverse Events. The NCI Common Terminology Criteria for Adverse Events is a descriptive terminology which is utilized for Adverse Event (AE) reporting. A grading (severity) scale is provided for each AE term. 2As assessed by the investigator. Missing responses are counted as related. §Grade 2 peripheral neuropathy; pancreatitis; ^grade 2 lleus BioAtla| Overview 15#16Potential market opportunity in metastatic NSCLC ~75-80% ● >540K ● people in the U.S. living with lung cancer¹ bicatla non-squamous represents majority of NSCLC patients ³ ~200K 2L+ newly diagnosed patients / year (U.S.) - majority advanced / metastatic² despite advances in 1L care, majority of patients progress4 Available Treatment: 1L: Chemo + ICI 50% ORR5 2L+: SOC 14% -23% ORR6: median PFS 4.5 months6 Target population: ~50K AXL+ addressable 2L+ patients/year in the U.S.7, based on AXL positivity rate of ~35% Internal success threshold: 2L+ ORR of ~20% (approvability bar based on precedent); 25%+ (commercially relevant) following BA3011 monotherapy small-cell/statistics, ¹https://www.lung.org/lung-health-diseases/lung-disease-lookup/lung-cancer/resource-library/lung-cancer-fact-sheet 2https://www.cancer.net/cancer-types/lung-cancer-non- ³https://thoracickey.com/carcinomas-of-the-lung-classification-and-genetics/#F1-72, 4Wang F, Wang S and Zhou Q (2020) The Resistance Mechanisms of Lung Cancer Immunotherapy. Front. Oncol. 10:568059. doi: 10.3389/fonc.2020.568059, 5Transl Lung Cancer Res 2021;10(7):3093-3105. 6Cyramza package insert (accessed March 2023) Clarivate, Disease Landscape and Forecast: NSCLC (2022). 1L, first line; 2L+, second line or greater; NSCLC, non-small cell lung cancer; ORR, objective response rate (best objective response as confirmed complete response or partial response), SOC, standard of care (docetaxel alone, docetaxel + ramucirumab) BioAtla| Overview 16#17Encouraging Phase 1 results with Mecbotamab Vedotin (BA3011) in refractory NSCLC patients Maximum Change From Baseline (%) 100 80 60 40 20 0 -20 -40 -60 -80 -100 bicatla AXL- TmPS=0 1.5mg/kg d1,8 Response at Variable Dosing AXL- TmPS=0 1.2mg/kg d1,8 *1.8mg/kg d1,8 = 2Q3W dosing regimen Not Evaluable 1.2mg/kg d1 Confirmed PR Stage IV adenocarcinoma (multiple chemo PKIs and pembrolizumab failure) AXL+ TmPS-80 1.8mg/kg d1,8* A partial response was achieved in the AXL+ NSCLC patient refractory to multiple chemo PKIs and pembrolizumab failure BioAtla| Overview 17#18Phase 2 study design with BA3011 (Mecbotamab Vedotin) in refractory NSCLC patients Interim analysis AXL+ ≥1 TmPS Monotherapy and in Combination with PD-1/L1 All patients refractory to PD-1/L1, EGFR and / or ALK inhibitors Use to determine TmPS cut- off and P2, part 2 dose Next step Applying exposure-response learnings Request FDA feedback re: Phase 2, part 2 Complete interim analysis* and select Phase 2, part 2 conditions Following FDA feedback, initiate Phase 2, part 2 (potentially registrational trial) *To be presented at a medical meeting. Phase 2, part 2 bicatla progression-free survival; SAE, serious adverse event; TTR, time to response. Monotherapy (BA3011), PD-1 failure NSQ NSCLC Potentially registrational Phase 2, part 2 patient number TBD pending discussion with FDA Endpoints Primary endpoints Confirmed ORR per RECIST v1.1 AES or SAEs Secondary endpoints DOR, PFS, ORR, DCR, TTR, OS NSQ, nonsquamous; AE, adverse event; BOR, best overall response; DCR, disease control rate; DOR, duration of response; ORR, objective response rate; OS, overall survival; PFS, BioAtla| Overview 18#19Phase 2, part 1 BA3011 NSCLC initial interim analysis supports advancing preparations for part 2 potentially registrational study in PD-1 failure NSCLC ORR (%) bicatla 50 45 40 35 30 25 20 15 10 5 0 25% 5/20 NSQ+SQ Interim data- Data cut-off of Jan 4, 2023 Average prior lines of therapy = 3 NSQ - non-squamous; SQ - squamous 28% 5/18 All NSQ 40% 4*/10 NSQ monotherapy PD-1 or EGFR failure 44% 4*/9 NSQ monotherapy PD-1 failure only Responses include 4 partial responses (*) and one complete response (**) 13% 1**/8 NSQ BA3011 + nivolumab 0/2 SQ BioAtla| Overview 19#20Change from baseline in sum of target lesions Non-Squamous / PD-1 Failure 60 40 // 20 -20 -40 -60 -80 -100 bicatla % Change in Target Lesions (Best Response) Non-Squamous & PD1 Failure Comb-non-Sq Mono-non-Sq Interim data- Data cut-off of Jan 4, 2023 Graphs represent patients who have had the opportunity to be followed for 12 weeks or more % Change in Target Lesions frm Baseline *Combo patients: 5 out of 7 patients discontinued due to either AEs related to nivolumab leading to treatment interruption and withdrawal (discontinued after 1 cycle; n=3) or worsening of existing brain metastasis (n=2). 60 40 20 -20 -60 -80 -100 0 5 сл % Change in Sum of Target Lesions Non-Squamous & PD1 Failure 10 15 20 Time (Weeks) 25 30 Mono Combo* 35 40 BioAtla| Overview 20#21Promising safety and tolerability profile continues to emerge in NSCLC Phase 2 at the RP2D 1.8 mg/kg Q2W Characteristic Any Adverse Events (AEs Related AEs with CTCAE¹ Grade 3 or 4² Any related serious AEs² Related AEs leading to death² Related AEs leading to treatment discontinuation² Constipation Peripheral Neuropathy BA3011 (N=18) 17 (94%) 5 (28%) 2 (11%)* Diarrhea 0 2 (11%) BA3011 + Opdivo (N=9) 9 (100%) 2 (22%) 3 (33%)^ All Grade 1-2 (11%) All Grade 1-2 (15%) All Grade 1-2 (15%) No grade 3 - 4 AEs related to constipation, peripheral neuropathy or diarrhea observed. Low-grade constipation observed is consistent with baseline levels seen in advanced cancer patients. 0 0 ■ ■ ■ ■ No treatment-related deaths Few treatment-related SAEs Few AEs leading to treatment discontinuation No clinically meaningful on-target toxicity observed over background Differentiated profile due to avoiding on-target off-tumor toxicity Interim data- Data cut-off of Dec 21, 2022 ¹CTCAE: Common Terminology Criteria for Adverse Events. The NCI Common Terminology Criteria for Adverse Events is a descriptive terminology which is utilized for Adverse Event (AE) bicatla reporting. A grading (severity) scale is provided for each AE term. 2As assessed by the investigator. Missing responses are counted as related. "DKA & infusion reaction "creatinine increase, diplopia unrelated to BA3011 post data transfer) & acute kidney injury; § DKA & infusion reaction BioAtla| Overview 21#22BA3011 Phase 2, part 1 NSCLC Key Takeaways ● Impressive response in monotherapy NSQ PD-1 failure population Promising durability of response Emerging safety profile continues to be differentiated Preparing for FDA interactions in 1H; while awaiting FDA feedback, evaluating more frequent, dose-intensive regimen similar to sarcoma NSQ PD-1 failure population represents a significant unmet need and commercial opportunity bicatla NSQ = nonsquamous BioAtla| Overview 22#23Dosing regimens under evaluation for CAB-AXL-ADC BA3011 Mecbotamab Vedotin All cycles (28 days) All cycles (21 days) Cycle 1 (21 days) Cycle 2 (28 days) and subsequent cycles bicatla Source: Form 10-K Q2W 2Q3W 3Q4W Day1 1.8 mg/kg Day 8 1.8 mg/kg 1.2 mg/kg Dose no drug 1.8 mg/kg 1.8 mg/kg 1.2 mg/kg 1.2 mg/kg Day 15 1.8 mg/kg no drug 1.2 mg/kg 1.2 mg/kg Day 22 no drug no drug BioAtla| Overview 23#24Summary of Dosing Regimens for Phase 2 Clinical Studies with CAB-AXL-ADC BA3011 Mecbotamab Vedotin Indication Soft tissue and bone sarcoma LMS UPS NSCLC Ovarian* bicatla Dose Q2W monotherapy and combo w/ nivolumab 3Q4W monotherapy 2Q3W monotherapy 3Q4W monotherapy Q2W monotherapy Q2W in combo w/ nivolumab 2Q3W monotherapy 3Q4W monotherapy Q2W in combo w/ durvalumab *Investigator-initiated trial. LMS, leiomyosarcoma; UPS, undifferentiated pleomorphic sarcoma; NSCLC, non small cell lung cancer. Patient # ~15 per cohort N~ 15 N~ 20 N~ 20 N~ 20 N~ 20 N~ 20 N~ 20 N~ 20 BioAtla| Overview 24#25bicatla CAB-ROR2-ADC Platform BA3021 Ozuriftamab Vedotin - NSCLC, Melanoma, SCCHN#26Potential market opportunity in metastatic NSCLC >540K ~75-80% ● people in the U.S. living with lung cancer¹ bicatla non-squamous represents majority of NSCLC patients ³ ~200K 2L+ newly diagnosed patients / year (U.S.) - majority advanced / metastatic² despite advances in 1L care, majority of patients progress4 Available Treatment: 1L: Chemo + ICI 50% ORR5 2L+: SOC 14% -23% ORR6: median PFS 4.5 months6 Target population: ~25K ROR2+ addressable 2L+ patients/year in the U.S.7, based on ROR2 positivity rate of ~20% Internal success threshold: 2L+ ORR of 20% (approvability bar based on precedent); 25%+ (commercially relevant) following BA3021 monotherapy small-cell/statistics, ¹https://www.lung.org/lung-health-diseases/lung-disease-lookup/lung-cancer/resource-library/lung-cancer-fact-sheet 2https://www.cancer.net/cancer-types/lung-cancer-non- ³https://thoracickey.com/carcinomas-of-the-lung-classification-and-genetics/#F1-72, 4Wang F, Wang S and Zhou Q (2020) The Resistance Mechanisms of Lung Cancer Immunotherapy. Front. Oncol. 10:568059. doi: 10.3389/fonc.2020.568059, 5Transl Lung Cancer Res 2021;10(7):3093-3105. 6Cyramza package insert (accessed March 2023) 'Clarivate, Disease Landscape and Forecast: NSCLC (2022). 1L, first line; 2L+, second line or greater; NSCLC, non-small cell lung cancer; ORR, objective response rate (best objective response as confirmed complete response or partial response), SOC, standard of care (docetaxel alone, docetaxel + ramucirumab) BioAtla| Overview 26#27Encouraging Phase 1 results with BA3021 (Ozuriftamab Vedotin) in refractory patients with NSCLC Maximum % Change from Baseline in Sum of Target Lesions bicatla 30% 20% 10% 0% -10% -20% -30% -40% -50% -60% ROR2 + (**TmPS=100) 1.2mg/kg d1,8 I I I I I Suboptimal dose (1.2mg/kg 2Q3W) ROR2 - (**TmPS=0) 3mg/kg d1 Patient experienced tumor shrinkage prior to progression of metastatic bone lesions Response at Variable Dosing ROR2 + (**TmPS=45) 3.3mg/kg d1 NSCLC squamous tumor: 10mm to 0mm on first scan Note: Not Evaluable (Strong, extensive fibroblastic stromal positivity reported) Not Evaluable 1.5mg/kg d1,8 ROR2 + (**TmPS=95) 3.3mg/kg d1 I ROR2 + (**TmPS=70) 3mg/kg d1 ¶ PR **Suboptimal dose 1.2 mg/kg 2Q3W. Tumor shrinkage occurred prior to progression of metastatic bone lesions. NSCLC squamous tumor 10mm to 0mm on first scan. ■ Two out of three ROR2+ patients had a partial response following ozuriftamab vedotin treatment BioAtla| Overview 27#28Potential market opportunity in metastatic melanoma ~1.3MM ● ~50% people in the U.S. living with melanoma¹ bicatla do not respond to PD-1 therapy in 1L setting² ~100K 30-40% newly diagnosed invasive cases / year (U.S.)¹ initial responders progress² Available Treatment 1L: ICIs 33% - 50% ORR³; (BRAF / Mek inhibitors for BRAF+) 2L+: ICIS 9% -28% ORR (mono - combo, respectively)4 Target population: ~5K ROR2+ addressable 2L+ patients/year in the U.S.1, based on a ROR2 positivity rate of ~10% Internal success threshold: 2L+ ORR of ~20% (approvability bar based on precedent); 25% + (commercially relevant) following BA3011 monotherapy ¹Clarivate, Disease Landscape and Forecast: Malignant Melanoma (2022). www.cancer.net; www.cancer.org; 2Oncology (Williston Park). 33(4):141-8. ³Keytruda USPI accessed June 2022; Opdivo USPI accessed June 2022. 4VanderWalde A, Moon J, Bellasea S, et al. Ipilimumab plus nivolumab versus ipilimumab alone in patients with metastatic or unresectable melanoma that did not respond to anti-PD-1 therapy. Presented at: 2022 AACR Annual Meeting; April 8-13, 2022; New Orleans, LA. Abstract CT013. 1L, first line; 2L+, second line or greater; ICIS - Immune checkpoint inhibitors. BioAtla| Overview 28#29Phase 1 & 2 results in stage IV multi-refractory melanoma complete response observed in 2 out of 2 ROR2+ evaluable patients %change in Target Lesions 100 80 60 40 20 0 -20 -40 -60 -80 -100 0 bicatla 20 Data on file. ROR2 + Phase 2 Patient (on treatment) 40 60 80 Time (weeks) 100 120 140 ROR2 + Phase 1 Patient 160 Phase 1 Patient Details: ✓ Prior treatment failure: nivolumab followed by nivolumab + ipilimumab combination ✓Clearance of pulmonary metastases followed by normalization of adenopathy ✓ Continued CR off-treatment for over 2 yrs Oo Phase 2 Patient Details: ✓ Prior treatment failure: nivolumab followed by dacarbazine ✓ Complete Response on 1st scan (3 doses) BioAtla| Overview 29#30Potential market opportunity in SCCHN ● >400K ~50% people living with head and bicatla neck cancer (U.S.)¹1 with locally advanced disease develop recurrent or refractory disease² ~66K 2L+ newly diagnosed cases / year (U.S.)¹ limited effective options post IL³ Available Treatment 1L: Pembro, cetuximab, platinum 36% ORR4 2L+: ICIS 13% -16% ORR4 Target population: ~12K ROR2+ addressable 2L+ patients/year in the U.S.1, based on a ROR2 positivity rate of ~60% Internal success threshold: 2L+ ORR of ~15% (approvability bar based on precedent); 15% + (commercially relevant) following BA3011 monotherapy ¹Clarivate, Disease Landscape and Forecast: SCCHN (2022). www.cancer.net; 2Argiris A, et al. (2017) Evidence-Based Treatment Options in Recurrent and/or Metastatic Squamous Cell Carcinoma of the Head and Neck. Front. Oncol. 7:72; ³Future Oncology, Jan. 2019. Vol. 15, No. 8; 4Ketruda USPI accessed June 2022; Opdivo USPI access June 2022. SCCHN, squamous cell carcinoma of the head and neck; 1L, first line; 2L, second line; 2L+, second line or greater; ICIS - Immune checkpoint inhibitors. BioAtla| Overview 30#31Phase 1 results with BA3021 support advancing into Phase 2 in multiple indications ROR2+ Tumor Types NSCLC Melanoma SCCHN bicatla Results ▪ PR in 2/3 patients who previously experienced failure on PD-1 and who received Phase 2 dose or higher ▪ CR in 1 / 1 patient who previously experienced failure on PD-1 - Clearance of pulmonary metastases followed by normalization of adenopathy ▪ Continued CR off treatment for over 2 years ▪ PR in 1/1 ROR2+ refractory to four prior lines of therapy including cetuximab and PD-1 (pembrolizumab) Promising safety and tolerability profile across multiple tumor types No ROR2 ADC or small molecules in the clinic to date, suggesting CAB-ROR2-ADC is a first-in-class therapy across multiple tumor types BioAtla| Overview 31#32Phase 2 study design with BA3021 (Ozuriftamab Vedotin) in refractory patients for each indication: Melanoma, NSCLC and SCCHN bicatla Total patients (n = 100) ● Phase 2 - Melanoma / NSCLC ● Melanoma: PD1 failure - (n = 40) Q2W NSCLC: PD1, EGFR or ALK failure - (n = 60) Q2W or 3Q4W Monotherapy and Combination with PD-1/L1 Use to determine TmPS cut-off and potential registrational study design Phase 2 - SCCHN Total patients (n = 40) SCCHN: Prior treatment with a PD-1/L1 inhibitor either administered alone (n = 20) or in combination with Platinum (n = 20) - Q2W ● Monotherapy Use to determine TmPS cut-off and potential registrational study design BioAtla| Overview 32#33Dosing regimens under evaluation for CAB-ROR2-ADC BA3021 Ozuriftamab Vedotin All cycles (28 days) All cycles (21 days) Cycle 1 (21 days) Cycle 2 (28 days) and subsequent cycles bicatla Source: Form 10-K Q2W 2Q3W 3Q4W Day 1 1.8 mg/kg Day 8 2.0 mg/kg 1.3 mg/kg Dose no drug 1.8 mg/kg 1.8 mg/kg 1.3 mg/kg 1.3 mg/kg Day 15 1.8 mg/kg no drug 1.3 mg/kg 1.3 mg/kg Day 22 no drug no drug BioAtla| Overview 33#34Summary of Dosing Regimens for Phase 2 Clinical Studies with CAB-ROR2-ADC BA3021 Ozuriftamab Vedotin bicatla Indication NSCLC Melanoma Head and Neck Ovarian* *Investigator-initiated trial. NSCLC non small cell lung cancer Dose Q2W monotherapy Q2W in combo w/ nivolumab 3Q4W monotherapy Q2W monotherapy Q2W in combo w/ nivolumab Q2W monotherapy Q2W in combo w/ durvalumab Patient # N~ 20 N~ 20 N~ 20 N~ 20 N~ 20 N~ 40 N~ 20 BioAtla| Overview 34#35Naked Antibody I/O Platform: CTLA-4 (BA3071) - Basket Trial bicatla#36BA3071 (CAB-CTLA-4) Best-in-class and potential for disruption of the I/O Market Research demonstrates challenges and opportunity in combining two Immune Checkpoint Inhibitors* I - Improves efficacy, but increases adverse events Greater % of patients discontinue therapy relative to monotherapy In NHP study, BA3071 achieved similar exposure levels to Ipi analog with significantly less toxicity in combination with nivo** bicatla Clinical Endpoint Progression Free Survival Grade 3 or 4 Adverse Events Discontinued Treatment Vehicle Control Nivo + Ipi Positive Control Nivo + CAB- BA3071 #1 #2 #3 #4 #5 #1 #2 #3 #**#*#4 Study date 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 Cvno # #1 or #2 #5 #1 #2 #3 #5 ●●● Nivolumab (PD-1) *Larkin et al., New Eng. J. Med.,373: 23-34, 2015; **Chang et al., PNAS 118 (9): 1-10, 2021 Nivo: 20mg/kg QW (12X human dose); Ipi or CAB-CTLA: 15mg/kg QW (45 - 60X human dose) Once weekly for four weeks exposure to Nivo + Ipi or CAB CTLA4 AUC168 = Area under the serum drug concentration-time curve from time zero to 168 hours; Cmax = Highest drug concentration observed in serum 6.9 months 16.3% 7.7% Nivolumab (PD-1) + Ipilimumab (CTLA4) 11.5 months 55.0% 36.4% GI Symptoms A Liquid feces Non-formed feces Other Gl symptoms BioAtla| Overview 36#37Phase 1/2 trial design for CAB-CTLA-4 Naked Antibody (BA3071) in tumors known to be responsive to CTLA-4 treatment FPI 3Q 2022 BA3071 7 mg Q3W (n=1-6) BA3071 21 mg Q3W (n=1-6) BA3071 70 mg Q3W* (n=1-6) BA3071 monotherapy Objectives (DLT period) BA3071 210 mg Q3W (n=3-6) ✓ I BA3071 in combination with nivolumab ■ BA3071 350 mg Q3W (n-3-6) BA3071 700 mg Q3W (n-3-6) RP2D selection bicatla *Dose equivalent to approved ipilimumab dose (1 mg/kg); Status as of May 4, 2023 Phase 2 Expansion in 2H 2023 Select Up to Two for Potential Phase 2 Dose Expansion Cohorts RCC n=40 Melanoma n=40 NSCLC n=40 SCLC n=40 Bladder n=40 ■ Determine Phase 2 dose and MTD Characterize safety and clinical activity of BA3071 monotherapy and in combination with a PD-1 inhibitor (Nivolumab) Characterize PK, ADA and biomarkers Gastric n=40 aHCC n=40 Cervical n=40 BioAtla | Overview 37#38bicatla Bispecific Platform CAB-EpCAM X CAB-CD3 (BA3182) - Adenocarcinoma#39BA3182 - CAB-EpCAMxCAB-CD3 significant opportunity for safe and effective EpCAMXCD3 bispecific EpCAM expressed on normal epithelial cells and overexpressed in a wide range of tumors (adenocarcinoma) CD3-bispecifics have demonstrated beneficial effects but hampered by dose-limiting toxicity, namely, cytokine release syndrome (CRS) 2500 Tumor volume (mm³) bicatla 2000 1500 1000 500 0 0 Tumor shrinkage Isotype x WT CD3 -EpCAM x WT CD3 ACAB EpCAM x CAB CD3 10 20 bispecific T-Cell Engager (TCE) 30 40 Study Days MiXeno Model with HCT116= Colorectal Cancer Cell Line 1mg/kg twice/week in mice (equivalent to 0.25mg/kg in non-human primates) 50 ● BA3182 exhibits efficient tumor shrinkage with superior safety profile • In non-GLP and GLP tox studies in NHP, dual selection results in high selectivity ► 160-fold TI increase MTD not reached (5mg/kg highest dose studied=NOAEL) No Cytokine release observed or other EpCAM or CD3 known related toxicities Safety Profile WT-EpCAM x WT-CD3 *0.025mg/kg = 2 ill *0.05 mg/kg = 2 expired *Single Dose - non-GLP Toxicity Study WT = wild type; *from independent experiments MTD Maximum Tolerated Dose TI = Therapeutic Index CAB-EpCAM x CAB-CD3 (BA3182) *0.25mg/kg = 2 normal *1.0 mg/kg = 2 normal *2.5 mg/kg = 2 normal *2.5 mg/kg = 10 normal *5.0 mg/kg 10 normal *QW x 4 weeks - GLP Toxicity Study = BioAtla | Overview 39#40FDA cleared IND for Phase 1/2 trial design in advanced adenocarcinoma Group A Accelerated Titration Convert to standard titration when any grade 22 AE (except AE due to the underlying disease or an extraneous cause) or a DLT DL8A: 125 µg/kg DL7A: 40 µg/kg ↑ DL6A: 12.5 µg/kg DL5A: 4 µg/kg DL4A: 1.25 µg/kg DL3A: 0.4 µg/kg DL2A: 0.125 µg/kg DL1A: 0.04 µg/kg bicatla ● ● • CAB-EpCAMXCAB-CD3 bispecific TCE (BA3182) Grade 22 AE or DLT Group B Standard Titration Dose escalation using the Bayesian Optimal Interval (BOIN) design MTD or PAD DL4B DL3B ↑ DL2B ↑ DL1B: highest dose tested in Group A Group C Standard Titration with Priming If one Grade > 2 CRS is observed, initiate priming dose evaluation Grade 22 CRS Priming Dose D1 PDLXC PDL2C PDLIC 1 ↑ CIDI MTD/PAD DL2C DL1C DLIA: MABEL based starting dose 0.04 µg/kg The actual number of dose levels (cohorts) in Accelerated Titration will depend on the dose level at which the first Grade 22 AE or DLT occurs MTD: Maximum tolerated dose; PAD: Pharmacologically active dose Dosing schedule: every week (QW) initially, every two weeks (Q2W) may also be explored PDL1C: first priming dose level; PDLxC: final priming dose level Part 1: Up to 128 patients with advanced adenocarcinoma ● ● Up to 8 patients in the accelerated titration Up to 60 in each of the 2-treatment schedules for 10 planned standard titration dose levels Part 2: Open-label study to evaluate the efficacy and safety of BA3182 in patients with advanced adenocarcinoma who have a qualifying EpCAM- expressing tumor membrane percent score (TmPS) (to be determined based on Part 1 data). BioAtla| Overview 40#41Many key milestones and catalysts throughout 2023 Submit BA3011 Exposure-Response analysis to medical meeting FPI BA3021 SCCHN Phase 2 1H Initiate BA3182 Phase 1 study Enrolling more frequent dosing regimens in BA3011 NSCLC Phase 2, part 1 FPI BA3011 UPS Phase 2, part 2 potentially registrational study Request FDA feedback re: BA3011 NSCLC Phase 2, part 2 potentially registrational study design FPI BA3021 NSCLC Phase 2 more frequent dosing regimens bicatla *Phase 2 Investigator-initiated trial combination with PD-1 (n=20) in platinum failure patients. FPI, First Patient In; LMS, Leiomyosarcoma 2023 Receive FDA feedback re: BA3011 NSCLC Phase 2, part 2 potentially registrational study design Initiate BA3011 NSCLC Phase 2, part 2 potentially registrational study 2H Prioritize BA3021 registration indications BA3071 Phase 1 data Initiate BA3071 Phase 2 study BA3011 Phase 2, part 1 LMS data BA3011 Phase 2 IIT* interim data (n=10) in platinum-resistant ovarian cancer BA3021 Phase 2 IIT* interim data (n=10) in platinum-resistant ovarian cancer BioAtla| Overview 41#42BioAtla® is a clinical stage company focused on transforming cancer therapy with Conditionally Active Biologics (CABS) Proprietary technology Broad applicability in solid tumors Increases therapeutic bicatla window Two Phase 2 CAB-ADCs, one Phase 1 CAB-I/O and one Phase 1 CAB-bispecific T-cell engager BA3011 advancing potentially registrational studies in sarcoma and NSCLC Diversified pipeline Clinical readouts for multiple indications through 2023 Strategic optionality Strong cash position $192.7 million in cash and cash equivalents as of 03/31/23 Sufficient through key clinical milestones into 2025 BioAtla| Overview 42#43Appendix bicatla#44BA3011 ADC Concentration vs Time Profiles from Different Dosing Regimens bicatla Cmax = SAFETY 50.00 20.00 10.00 5.00 2.00 1.00 0.50 0.20 0.10 0.05 Cmin & Frequency = EFFICACY 0 7 14 21 28 35 Median 1.8 mg/kg Q2W Median 1.8 mg/kg 2Q3W Median 1.2 mg/kg 3Q4W (1.8 mg/kg Starting Dose) 42 49 56 Nominal Time Since First Dose (days) ADC = antibody-drug conjugate; 2QW = every two weeks; 2Q3W = twice every 3 weeks; 3Q4W = three times every 4 weeks Cmax: maximum concentration, Cmin: minimum concentration 63 70 77 BioAtla| Overview 44