#1Breakthrough antibody technology to broaden therapeutic window of anti-cancer drugs December 2020 bigatla#2Important Notices & Disclaimer bicatla This presentation (the "Presentation") is not a prospectus and it shall not constitute an offer to sell or the solicitation of an offer to buy, nor shall there be any sale of, the securities in any state or jurisdiction in which such an offer, solicitation or sale would be unlawful prior to registration or qualification under the securities laws of such state or jurisdiction. BioAtla, Inc. ("we", "us", "our", "BioAlla", or the Company") has filed a registration statement (File No. 333-250093), which includes a preliminary prospectus, with the Securities and Exchange Commission (SEC") for the offering to which this Presentation relates. The registration statement has not yet become effective. Our securities may not be sold, nor may offers to buy be accepted, prior to the time the registration statement becomes effective. Before you invest in any such securities, you should read the preliminary prospectus in that registration statement and other documents we have filed with the SEC for more complete information about us and this offering. You may obtain these documents for free by visiting EDGAR on the SEC website at www.sec.gov. Alternatively, copies of the preliminary prospectus may be obtained from J.P. Morgan Securities LLC, c/o Broadridge Financial Solutions, 1155 Long Island Avenue, Edgewood, New York 11717, Attention: Prospectus Department or by calling (866) 803-9204; Jefferies LLC, Attention: Equity Syndicate Prospectus Department, 520 Madison Avenue, 2nd Floor, New York, NY 10022, or by telephone at 877-547-6340 or by email at Prospectus [email protected]; or Credit Suisse Securities (USA) LLC (Attention: Prospectus Department, 6933 Louis Stephens Drive, Morrisville, NC 27560, or by telephone at (800) 221-1037, or by email at [email protected]). The Presentation does not purport to be a prospectus, to be complete or to contain all of the information you may desire. This Presentation 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. 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 of 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 neither this Presentation, nor any sale of securities, shall 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 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 contains 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. 2#3Offering Summary Issuer: Ticker/ Exchange: Base offering size: Overallotment option: Use of proceeds: Bookrunners: Co-manager: Expected pricing: Lock-up: Note: Conditionally Active Biologic (CAB) BioAtla, Inc. BCAB/Nasdaq Global Market 9,400,000 shares (-$150.0 million, 100% primary) 1,410,000 shares (100% primary, 15% of base deal) BioAtla intends to use the net proceeds from this offering as follows: • Fund the clinical development of BA3011 in soft tissue and bone sarcoma patients through a Phase 2 clinical trial, and for the treatment of NSCLC patients through Phase 2 bicatla • Fund clinical development of BA3021 for the treatment of NSCLC and for the treatment of melanoma, each through Phase 2 • Fund IND-enabling studies and initial Phase 1 clinical supply of our first two CAB¹ bispecific candidates BTIG • Fund ongoing efforts to develop additional clinical product candidates from BioAtla's CAB platform • Working capital and other general corporate purposes J.P. Morgan, Jefferies, Credit Suisse Tuesday, December 15th, 2020 180 days for the Company, directors, officers and all other pre-IPO shareholders#4BioAtla at a Glance The Company Proprietary CAB technology creates antibodies that conditionally and reversibly bind to tumors, but not normal cells, enabling increased antibody potency and reduced toxicity Strong intellectual property rights, with 257 patents issued, 8 allowed applications, and 214 pending applications ⠀ 54 employees and contractors, with 10 employees holding Ph.D. degrees, and 1 with an M.D. degree · Reputable investor base with $166 million raised to date, with $72.5 million in recent Series D financing Committed BeiGene collaboration with $25 million received to date, and eligible to receive up to $225.5 million in future milestone payments Headquartered in San Diego, California in a -43,000 square foot office and lab facility Investor Base BOXER CAPITAL CORMORANT ASSET MANAGEMENT FARALLON Janus Henderson INVESTORS bicatla HBM Healthcare Investments Pfizer Ventures pappas CAPITAL SOLEUS CAPITAL#5Highly Experienced Management Team Jay Short, Ph.D. Chairman, CEO and Cofounder DIVERSA STRATAGENE life Eric Sievers, M.D. Chief Medical Officer SeattleGenetics ZYMOGENETICS Philippe Martin, M.S., M.B.A. Chief of Clinical Development & Operations William Boyle, Ph.D. Research Fellow FRED HUTCH Cogene op Schering-Plough Aventis Anaptys Bio AMGEN salk Scott Smith, M.S., M.B.A. President Celgene Cathy Chang, Ph.D. VP, Research & Development, Asia SYNTHETIC GENOMICS BIOVAIL Capia P DIVERSA Carolyn Anderson Short Chief of IP & Strategy and Cofounder DIVERSA Richard Waldron, M.B.A. Chief Financial Officer bicatla INTREXON GeneMedicine, Inc. PHARMACIA STRATAGENE Pacific STRATAGENE Biotech COWEN Experienced Team with Protein Discovery and Evolution, Clinical Development and Intellectual Property Expertise 5#6BioAtla - Exceptional Opportunity to Create Value Proprietary CAB Antibody Platform Advantages over traditional antibodies ■ Conditional and reversible binding enables increased antibody potency and reduced toxicity Increased drug exposure and improved pharmacokinetics Broader universe of tumor-specific antigen targets Significant Potential for Clinical Assets Two Phase 2 CAB ADCs¹ (AXL & ROR2) Phase 1 data show highly differentiated benefit/risk in patients Significant commercial potential for both assets ■ Initiated Phase 2 dosing ADC (Antibody Drug Conjugate); Immuno-oncology (1/O) Validating Global Collaboration CAB CTLA-4 BeiGene collaboration CAB CTLA-4 could be integral to future 1/0² combinations ■ $25 million in payments received from BeiGene to date; $225.5 million in potential milestones ■ Tiered royalties with highest tiers >20% bicatla Broad Development Pipeline Other differentiated CAB molecules ■ Productive platform capable of bringing forward unique CAB molecules ■ Pipeline focus on naked antibodies, bispecifics and ADCs ■Broad set of potential products#7Type ADC Robust Pipeline of Antibody-Based Therapeutics CAB Program CTLA-4 Bispecific Bispecific BA3011 AXL (AXL-ADC) Positive BA3021 ROR2 (ROR2-ADC) Positive BA3071 (CTLA-4) Target BA3182 (Bispecific) CTLA-4 EGFR (Bispecific) EpCAM / CD3 BA3142 87-H3 (Bispecific) / CD3 Target EGFR /CD3 Nectin-4 (Bispecific) /CD3 Nectin-4 Indications Research and Discovery Product Candidates Туре CAB Program Indications STS & Bone Sarcoma, NSCLC, Ovarian Cancer (Mono & Combo w/ PD-1) NSCLC, Melanoma, Ovarian Cancer (Mono & Combo w/ PD-1) RCC, NSCLC, SCLC, HCC, Melanoma, Bladder, Gastric, Cervical Cancer (Mono & Combo w/ PD-1) NSCLC, SCLC, Colorectal, Ovarian, TNBC, Prostate Cancer** NSCLC, SCLC, HNC, Melanoma, Sarcoma, Pancreatic, Prostate Cancer** NSCLC, HNC, Pancreatic, TNBC, Colorectal Cancer** Bladder, TNBC, Pancreatic Cancer** Discovery Discovery IND Enabling IND Enabling Phase 1 Phase 1 Phase 2 BeiGene Phase 2 Phase 3 Phase 3 H Expected Upcoming ■ " H " I bicatla Milestones H Ph2 interim data 2021 Ph2 registration data 2022 H Ph1 dose escalation trial to be initiated in 2021 Ph2 interim data 2021 Ph2 registration data 2022 US IND in 1H 2022 US IND In 2022 Expected Upcoming Milestones US IND in 2022 " US IND In 2022 Abbreviations: STS = Soft Tissua Sarcoma, NSCLC = Non-small Call Lung Cancer, RCC = Renal Call Carcinoma, SCLC = Small Call Lung Cancer, HCC = Hapatocellular Carcinoma, TNBC = Triple- Negative Breast Cancer, HWC-Head and Neck Cancer: "Ph2 investigator initiated trial for Ovarian Cancer expected to be initiated by the end of 2020 or early 2021 ** Anticipated indications based upon tumor target expression 7#8CAB Technology Leverages Differential pH of Cancer Cells bicatla Normal Human Environments Typically Have Alkaline pH Arterial Blood 7.4-7.45 Capillary Blood 7.35-7.4 Venous Blood 7.35-7.45 Bile 7.8 Saliva 6.0-7.4 Brain Heart 7.0-7.4 Gastric Secretion. 1.0-3.5 Liver 7.2 Pancreatic Secretion 8.0-8.3 • Small intestine Secretion 7.5-8.0 Skeletal Muscle 6.9-7.2 Urine. 4.5-8.0 Bone. 7.4 Antibodies cannot access Saliva, Gastric Secretions, or Urine pH of normal environments that antibodies access Segmented image Tumor Environments Are Acidic With Lower pH Levels pHLIP intensity heat map <pH6.5 1 CAB antibodies allow for selective targeting of cancer tumor cells, based on pH, while generally not binding to normal tissue 2+ Acidic Cells • 87% oxygenated cells . 68-82% replicating cells 27-41% non-dividing cells Tumor-stroma boundary 2 This leads to the potential for enhanced therapeutic exposure & reduced toxicity compared to traditional antibodies MIT Study: Rohani, et al (2019) CancerRes 79:1952. (eg. Breast Cancer Cells) 8#9CABS Bind Selectively and Reversibly Based on the TME, Enhancing Exposure and Reducing Toxicity CABS Bind Selectively in the Lower pH TME CAB and Affinity Matched (AM) non-CAB AXL mAbs 2.5- ELISA Data OD450nm 1.5- Ab-ADC (ng/mL) 1.0- 0.5- 0.0- 5.5 10000 1000 Enhanced ADC Therapeutic Exposure AXL ADCs-1mg/kg dose 100 6.0 6.5 7.0 pH value 10 Blood 50 Non-CAB CAB 7.4 is pH of normal cell 150 100 Time (Hours) • CAB improves pharmacokinetics by eliminating TMDD CAB-ADC male CAB-ADC female 200 AM-ADC male AM-ADC female Selective Binding Reduced ADC Toxicity ALT (u/L) 1500 1000- Focused Tumor Killing 500- Pre- Treatment Post- Treatment bicatla Normal Cells Preserved AM Non-CAB AXL-ADC CAB AXL-ADC Day -3 Day 3 Study Day . CAB ADC resulted in minimal increase in ALT, supporting that on- target, off-tumor toxicity is reduced with the CAB ADC Unlike prodrugs, CABS are reversible, enhancing the therapeutic index Note: OD450nm = optical density measurements using a microplate reader with a 450nm filter: TME = Tumor Micro Environment; mABs = monoclonal antibodies; Data above based on non-human primate studies; AM= affinity matched, ALT or alanine aminotransferase is a sign of liver toxicity; TMDD = Tissue Mediated Drug Deposition#10AXL: Well-Validated Target Among Multiple Indications 1 Disease Progression AXL's higher expression associated with disease progression in several indications, including: - Sarcoma, NSCLC, ovarian cancer, breast cancer, pancreatic cancer, glioblastoma, melanoma, RCC, prostate cancer, and esophageal cancer Tumor type Sarcoma (STS & Bone) NSCLC Ovarian Cancer 2 Patient treatment phase Stage III/IV Stage III/IV (PD-1/L1 experienced) Stage III/IV Platinum resistant Tumor Resistance AXL expression associated with tumor resistance to: - Chemotherapy, PD- 1/L1 inhibitors, molecular targeted therapy, and radiation therapy 10,000-15,000 Initial US Addressable Patient Population Est. corresponding US patient population 66,000² 3 12,000 Clinical Validation AXL has been clinically validated as a target: - Multiple assets in the clinic including non-specific small molecules and antibody ADCs - Some anti-AXL antibodies in the clinic have shown encouraging signs of antitumor activity: however, adverse events may limit clinical utility and/or potency Est. AXL positivity rate¹ 50% 30% 30-40% Source: BioAtla IHC assay validation results & phase 1 AXL testing data, GlobalData-Opportunity Analysis and Forecasts, SEER database Based on TmPS (Tumor membrane Percent Score) 275% of these patients generally switch to a new therapy bigatla Est. US target population at launch 5,000-7,500 15,000 4,000 10#11AXL Targeting: Opportunity to Fill Treatment Void in Sarcomas bicatla Unmet need drives lower regulatory hurdles and higher market demand, representing opportunity -57% of our Sarcoma patients are AXL positive (TmPS ≥ 70)¹, supporting AXL opportunity BA3011 (AXL-ADC) has high potential to treat sarcoma successfully and fulfill opportunity Unmet Need for Sarcomas • Bone sarcomas have no approved therapies after failure of frontline regimens • No targeted therapies available for most soft tissue sarcoma • Low 5-year survival rates (-16.4% for late-stage metastatic soft tissue sarcoma) Lower Regulatory Hurdles for Sarcoma Treatments • Approved therapies generally show improved ORRS² of less than 15% 100% 75% 50%- 25% Pembrolizumab Nivolumab Eribulin Pazopanib Dacarbazine Figitumumab Aldoxorubican Yondelis Pembrolizumab //// Doxorubicin Apatinib Tazemeostat * Approved Gemacitabine *Docetaxel Cabozantinib 15% ORR Large and Under-Appreciated Commercial Opportunity • Lilly's olaratumab given accelerated approval for combination treatment for sarcoma in 2016 • Before withdrawal from market for failing Phase 3, olaratumab had sales of $562 million with a 50% CAGR, in less than 2 years Note: TmPS-Tumor membrane Percent Score- Scores range from 0 to 100, "Objective response rates (ORR) is defined as the proportion of patients with tumor size reduction of a predefined amount and for a minimum time period and is comprised of complete responses and partial responses; Pembrolizumab ORR data from 2015-2016 Pembrolizumab ORR data from 2017 SORR for Gemcitabine treatment in combination with Docetaxel 11#12BA3011: Encouraging Results in AXL High (TmPS 270) Sarcoma Patients at 1.8mg/kg Sarcoma (confirmed TmPS** 270; 1.8mg/kg Q3W or 2Q3W) Maximum % Change from Baseline in Sum of Target Lesions 100 80 -40 -80 -100 AXL+ TmPS-90¹1 I 1.8mg/kg d1,8 Tumor may not accurately represent AXL. expression at time of treatment due to outdated age of tissue sample AXL+ TmPS=100 1.8mg/kg d1,8 Leiomyosarcoma Uterine I (LMS) LMS TmPS-90 1.8mg/kg LMS (NED") * Confirmed Partial Response (PR) Out of 61 sarcoma patients screened for AXL Tumor Membrane Expression: • 35 had a TmPS ≥ 70 (57%) AXL+ TmPS=70 1.8mg/kg d1,8 UPS Patient case study on right side AXL+ TmPS-95 1.8mg/kg d1,8 UPS AXL+ TmPS-100 1.8mg/kg Ewing 4 partial responses out of 6 for sarcoma patients with TmPS 270 at the optimal dosing levels Note: "AXL Tumor membrane Percent Score or TmPS = % Score 21+ *Tissue biopsy from resection, over 1 year old prior to trial entry All patients: Multiple cycles of antineoplastic agents received prior to starting treatment with BA3011; INED = No evidence of disease bicatla LMS Patient Case Study Pre-treatment Post-treatment, week 18 Scan 37% tumor reduction . Tumor mass reduced enough to enable successful surgical resection resulting in NED¹ 12#13BA3011: Encouraging Results in NSCLC AXL High (TmPS 270) Patient at 1.8mg/kg Maximum Change From Baseline (%) 100 80 80 18 0 A 9 8 -100 AXL- TmPS=0 NSCLC (All Patients) TmPS=0 Not Evaluable Confirmed PR Stage IV adenocarcinoma (multiple chemo PKIs and pembrolizumab failure) AXL + TmPS=80 bicatla Note: All patients: Multiple cycles of antineoplastic agents received prior to starting treatment with BA3011 Stage IV adenocarcinoma patient case study • Patient experienced multiple failures of prior treatments . Prior treatment with PD- 1 inhibitor (pembrolizumab) failed -70% tumor reduction after BA3011 dosed at 1.8 mg/kg 2Q3W Out of 4 NSCLC patients, partial response achieved in the one patient with TmPS ≥ 70 13#14BA3011 is Well Tolerated at 1.8mg/kg Q3W or 2Q3W Overview of adverse events in BA3011 Phase 1 trial Few grade 3 or greater AES AEs consistent with MMAE-based toxicity, including: - reversible myelosuppression - transient liver enzyme elevation - metabolic disturbances None of the related AEs led to treatment discontinuation Patients administered 1.8mg/kg Q3W (d1) or 2Q3W (d1,8) (safety population) Characteristic Any Adverse Events (AES) Related AEs with CTCAE¹ Grade 3 or 4² Any related serious AEs AEs leading to death Related AEs leading to death? Related AEs leading to treatment discontinuation² BA3011 BA3011 1.8 mg/kg Q3W 1.8 mg/kg 2Q3W (N=9) (N=20) 9 (100%) 17 (85%) 2 (22%) 6 (30%) 3 (15%) 0 0 1 (11%) 1 (11%) 0 0 0 Cross-Trial Comparison Constipation Enapotamab vedotin (AXL-ADC) • Grade 1-2 (49%) • Grade 3-4 (9%) bicatla BA3011 (CAB AXL-ADC) • Grade 1-2 (16%) Grade 3-4 (4%) Constipation is believed to be an on-target mediated effect Peripheral Neuropathy³ Enapotamab vedotin (AXL-ADC) • PN rates (38%) BA3011 (CAB AXL-ADC) • PN rates (18%) Difference believed due to advantageous pharmacokinetic characteristics of CAB ADC vs. non-CAB ADC Note: "CTCAE: 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. As assessed by the investigator. Missing responses are counted as related. 14#15BA3011 AXL-ADC Phase 2 Clinical Program Potentially Registration-Enabling Phase 2 Trials (RP2D: 1.8mg/kg Q2W) STS Bone sarcoma STS & Bone sarcoma Phase 2 - Sarcoma-mono and/or combo with PD-1; BA3011 dose: 1.8mg/kg Q2W; AXL TmPS 270; 3rd line n=165-240 BA3011 Monotherapy (n=40) BA3011 Monotherapy (n=30) Combo with PD-1 (n=20) CD20 positive and negative Phase 2 NSCLC mono & combo with PD-1 in PD-1 exposed patients (n=20) Timeline Sarcoma: • 3rd line patients (chemotherapy failure) Interim analysis Selected ST5 & bone subtypes (n-150) mono &/or combo w PD-1 AXL positive Primary endpoint: ORR Matching population synthetic arm Phase 2 Population Proof Of Concept read-out (POC) Secondary endpoints: "PFS; OS Data read-out Ovarian Investigator-Initiated Trial (IIT) not shown NSCLC: • Prior disease progression on PD- 1/L1 inhibitor Note: "TmPS= Tumor membrane Percent Score-Scores range from 0 to 100; "PFS progression-free survival, OS = overall survival bicatla 15#16ROR2 Targeting: Significant Commercial Opportunity ROR2 Over-expression 1 Over-expressed across many solid tumors, including NSCLC, melanoma, ovarian, TNBC, and HNC Tumor type NSCLC Melanoma Ovarian Cancer Enhanced ROR2 Expression 2 Patient treatment phase Stage III/IV (PD-1/L1 inhibitor) Immune checkpoint inhibitor Stage III/IV Platinum resistant Enhanced ROR2 expression with prior PD-1/L1 treatment Initial US Addressable Patient Population Est. corresponding US patient population 66,000² 25,000² 12,000 3 Nascent Competition Est. ROR2 positivity rate¹ 30% No other ROR2 ADC or small molecules in the clinic yet, but competition is emerging 20-30% 30-40% Source: BioAtia IHC assay validation results & phase 1 AXL testing data, GlobaiData-Opportunity Analysis and Forecasts, SEER database; Based on TmPS (Tumor membrane Percent Score) 75% of these patients generally switch to a new therapy bicatla Est. US target population at launch 15,000 5,000 4,000 16#17BA3021: Encouraging Results in Stage IV PD-1 Refractory NSCLC Patients All evaluable NSCLC patients enrolled in BA3021 Phase 1 trial Maximum % Change from Baseline in Sum of Target Lesions 30% 20% 10% -10% -20% -30% -40% -50% -60% ■ ROR2 + **TmPS-100 ROR2- (**TmPS D Suboptimal dose (1.2mg/kg 2Q3W) ROR2 + Not (**TmPS-45) Evaluable Patient experienced tumor shrinkage prior to progression of metastatic bone lesions 1.2mg/kg d1,8 NSCLC squamous tumor: 10mm to 0mm on first scan 11.5mg/kg d1,8 ROR2 + 13.3mg/kg di * PR ROR2 + (**TmPS-70) 3mg/kg di bicatla Clinical results show promise in refractory patients 2 All NSCLC patients who enrolled in this trial had previously been treated with PD-1 therapy ROR2 expression strongly correlates with anti-tumor response Note: Not Evaluable (Strong, extensive fibroblastic stromal positivity reported) **TmPS= Tumor membrane Percent Score-Tumor membrane target expression calculated by summing the percentages of intensities at either 21+, 22+ or 23+, Scores range from 0 to 100, 17#18BA3021: Encouraging Results in Stage IV PD-1 Melanoma Patient All evaluable metastatic melanoma patients enrolled in BA3021 Phase 1 trial by ROR2 TmPS 0.6 mg/kg (d1) 3.0 mg/kg (d1) Change in target lesion from baseline (%) 100 50 0 -50 -100 0 10 O Visible tumor Confirmed PR 20 Time (weeks) Pre-treatment CT scan ROR2- Pre-treatment posterior occipital lymph node biopsy: Active melanoma "Biopsy: consistent with metastatic melanoma... consists of fibrous stroma and a relatively pure population of malignant melanoma cells... One of two melanoma patients enrolled in the BA3021 Phase 1 dose escalation trial achieved a partial response (Purple line) • Patient with PR experienced failure of both nivolumab & nivolumab + ipilimumab; now continuing BA3021 > 1 yr, consistent with results below bicatla 30 Lung lesion no longer visible ROR2 Not evaluable 40 On-treatment; Week 6 Scan On-treatment posterior occipital lymph node biopsy: No melanoma detected "Final pathology results: dense fibrous connective tissue with abundant melanin-laden macrophages, no melanoma seen..." 18#19BA3021: ROR2 Safety Profile at 1.8mg/kg Q3W or 2Q3W bigatla Overview of adverse events in BA3021 Phase 1 trial AEs consistent with MMAE-based toxicity, including: - reversible myelosuppression - transient liver enzyme elevation - metabolic disturbances Characteristic Any AEs Related AES with CTCAE Grade 3 or 4¹ Any related serious AEs¹ Related AEs leading to death¹ Related AEs leading to treatment discontinuation¹ Few grade 3 or greater AES Patients administered 1.8mg/kg Q3W (d1) or 2Q3W (d1,8) (safety population) BA3021 1.8 mg/kg (Q3W) (N=3) 3 (100%) 1 (33%) Note: "As assessed by the investigator. Missing responses are counted as related 0 0 None of the related AEs led to treatment discontinuation 0 BA3021 1.8 mg/kg (2Q3W) (N=7) 7 (100%) 3 (43%) 2 (29%) 0 0 19#20BA3021 ROR2-ADC Phase 2 Clinical Program Potentially Registration-Enabling Phase 2 Trials (RP2D: 1.8mg/kg Q2W) Timeline Phase 2 Program- NSCLC mono & combination w PD-1 ROR2 Positive: PD1-refractory n=200 Phase 2 Program-melanoma mono & combination w PD-1 ROR2 Positive; PD1-refractory n=200 1 NSCLC: Prior disease progression on PD- 1/L1 inhibitor Interim analysis n=20 Primary endpoint: ORR Population matched synthetic arm Note: Ovarian IIT not shown Phase 2 population Data read-out Melanoma: Prior disease progression on PD- 1/L1 inhibitor bicatla 20#21CAB ADC Phase 1 Program Summary ✔ ✔ Encouraging Results BA3011 (CAB-AXL-ADC) 5 PRs: 4 in sarcoma & 1 in NSCLC (PD-1 refractory) Durable response (8+ months) Tumor reduction results: - 4 Sarcoma PRs = -37%, -45%, -50%, -90% reduced - 1 NSCLC PR = -70% reduced ✔ ✔ BA3021 (CAB-ROR2-ADC) 4 PRs: 2 in NSCLC, 1 in melanoma, and 1 in HNC Durable response (8+ months) Tumor reduction results: - 2 NSCLC PRs = -31% and -49% reduced F - 1 Melanoma PR = -80% reduced -1 HNC PR = -54% reduced bicatla Promising Safety Profile > BA3011: Significant decrease in on-target, off-tumor toxicity and favorable safety profile vs. enapotamab vedotin > BA3021: Generally well- tolerated and did not observe AEs that appear to be related to on-target injury of normal, ROR2 expressing tissues > Limited on-target toxicity (AXL or ROR2) identified to date Phase 2 underway with interim data planned 2021; Phase 2 registration data planned 2022 21#22CAB CTLA-4: Potential for Disruption of the I/O Market Opportunity exists for a "safer" CTLA-4 inhibitor Outcomes • Traditional combination of anti-PD- 1 and anti-CTLA-4 checkpoint inhibitor led to improved outcomes Clinical Endpoint Progression Free Survival Grade 3 or 4 Adverse Events Discontinued Treatment Adverse Events Combination associated with increase in adverse events and treatment discontinuations Nivolumimab (PD-1)¹ 6.9 months 16.3% 7.7% Source: Larkin et al., New Eng: J. Med 373:23-34, 2015 X Unmet Need • A safe combo of PD-1/CTLA-4 has potential across many immunogenic tumors • Usage and dosage of ipilimumab (CTLA-4 inhibitor) highly limited due to its safety profile (average # of cycles on therapy does not exceed 4 cycles) bicatla Nivolumimab (PD-1) + Ipilimumab (CTLA-4)¹ 11.5 months 55.0% 36.4% • Ipilimumab dose in combination with Nivolumimab is 1/3 to 1/10 the monotherapy level, but still results in high toxicity BeiGene Global collaboration with BeiGene in place to maximize value 22#23BA3071: Equivalent Results and Enhanced Safety in Preclinical Models Results in human CTLA-4 engineered mouse model 4000 Isotype control (0/8 CR) Ipi-Analogue (1/8 CR) 3000- BA3071 (2/8 CR) *** Tumor volume (mm) 2000- 1000- Nivo +Ipi Positive Control Animal # #1 Vehicle Control #3 Nivo CAB-BA3071 #2 2 Combination I/O Non-Human Primate Toxicity Study Results Study date #4 #5 10 Study Day #1 or #2 02 #3 #4 #5 #1 #2 # 3 #4 # 5 15 20 Primate dosing levels (Nivo + Ipi) and (Nivo + BA3071): • PD-1 = 20mg/kg QW . CTLA-4= 15mg/kg QW bicatla Primate dosing ratio Compared to std. human dose • PD-1 dosed at 12x . CTLA-4 dosed at 45 - 60x 1 Despite high doses, Nivo + CAB-BA3071 demonstrates impressive safety results, especially compared to Nivo + Ipi BA3071 demonstrates similar results to Ipi, but exhibits more selective targeting, which is associated with fewer toxicities 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 GI Symptoms Liquid feces Non-formed feces Other Gl symptoms Chart reflects once weekly exposure 23#24BA3071: Global Strategic Collaboration BeiGene Demonstrated BeiGene Commitment • BeiGene holds an exclusive global license to BA3071 • BioAtla has received $25 million in upfront payments & reimbursement • BioAtla eligible to receive up to $225.5 million for subsequent regulatory and development milestones • BioAtla eligible to receive tiered royalties of up to low 20's on worldwide sales Note: 'Equivalent to 10mg/kg of ipilimumab Clinical Development Timeline bicatla Expected Phase 1 dose escalation trial in 2021 • Doses of 7mg Q3W to 700mg Q3W¹ as monotherapy and in combination with tislelizumab . Tislelizumab is an anti-PD-1 antibody in late-stage development by BeiGene Collaboration & Support • BeiGene leads Development, Manufacturing and Commercialization activities 24#25BioAtla's Butterfly CAB Bispecific Platform (CAB)*-TAA CAB-CD3 Higher safety, longer T1/2 simple manufacturing CABS have potential to reduce systemic activation for greater safety and efficacy A Reduced cytokine release syndrome and neurological toxicity Note: "Optional CAB directed against the tumor associated antigen (TAA) Tumor cell (CAB)*-TAA CAB-CD3 T cell Enables T cell engaging therapies with high potency while limiting T cell exhaustion bicatla Four active bispecific programs (BA3182, BA3142, EGFR, Nectin-4) 25#26Tumor volume (mm³) CAB-EpCAM x CAB-CD3 Bispecific Antibody Exhibits Comparable Results, While Maintaining Superior Safety Profile bicatla Commentary IL-6 (pg/mL) CAB EpCAM bispecific demonstrates tumor shrinkage 2500 2000 1500 1000 500 0 2000 1500 1000 CAB EpCAM exhibits lower IL-6 levels 600 400 200 5 0 -Vehicle -EpCAM x WT CD3 CAB EDCAM x CAB CD3 -Isotype x WT CD3 20 Study days Xenograft Model with HCT116= Colorectal Cancer Cell Line 2.5mg/kg twice/week in mice (roughly equivalent to 0.2mg/kg in non-human primates) 10 15 0.05mg/kg 25 EpCAM x WT CD3 EpCAM x CAB CD3 BF3 30 35 • CAB EpCAM bispecific antibodies have long lives and maintained comparable results to non-CAB bispecific antibodies . Low toxicity observed and lower levels of IL-6, an inflammatory cytokine, after treatment with EpCAM x CAB-CD3 vs EPCAM x WT-CD3 antibody Non-CAB EpCAM Bispecific Safety Results Non-human Primates 0.25mg/kg = 2 expired 0.05mg/kg = 1 expired; 1 ill (recovered) 0.025mg/kg = 2 ill (recovered) * Marked increase in ALP, ALT, AST, TBIL, CK were noted, with Gl and kidney function impacted * Hepatocellular and cholestatic injury was identified CAB EpCAM Bispecific Safety Results Non-human Primates 0.25mg/kg = 1 healthy; 1 ill (recovered) 0.05mg/kg = 2 healthy 0.025mg/kg = 2 normal ✓ Only high doses create early signs of toxicity Low toxicity observed at the lower doses Lower levels of IL-6 generated and no deaths 26#27Upcoming Inflection Points Expected Multiple Near-term Regulatory, Clinical Safety and Efficacy Read-outs Program BA3011 (AXL) BA3021 (ROR2) BA3071 (CTLA-4) Bi- specific 1H Note: "Ovarian IT not shown 2020 2H 1H 2021 2H Phase 2 in Soft Tissue & Bone Sarcoma Phase 2 NSCLC (n=20) Phase 2 Interim Data Readout¹ Phase 2 Interim Data Readout¹ Phase 2 in NSCLC & Melanoma Phase 2 Interim Data Readout¹ Phase 1 Dose Escalation 1H IND Filling BA3182 2022 2H bicatla Phase 2 Pivotal Data Readout Phase 2 Data Readout IND Filing BA3142. EGFR. Nectin-4 27#28BioAtla's Pioneering Work Yields Substantial IP Portfolio bicatla 257 Issued Patents 8 Allowed Patent Applications 214 Pending Patent Applications Note: Information as of December 2020 BioAtla's CAB Technology and Products Patent Coverage Worldwide patent coverage with issued and pending applications in all major market/manufacturing countries . Broad patent coverage including: methods of making and screening CAB antibodies different formats (e.g. ADC, multi- & bi-specific, CAR-T, mAbs and proteins) specific antibodies (composition of matter) Broad coverage provides a patent minefield where products are not dependent on a single patent for protection 28#29Financial Overview Strongly capitalized with support from reputable investors BOXER $166 million raised since inception $72.5 million Series D financing round raised in July 2020 CAPITAL HBM Healthcare Investments CORMORANT ASSET MANAGEMENT Janus Henderson Pfizer Ventures -INVESTORS- FARALLON pappas CAPITAL SOLEUS CAPITAL bicatla 29#30Summary and Conclusions BioAtla is well positioned to develop a strong franchise of CAB-enabled treatments ID 肿 Innovative CAB technology platform, with clinically-validated antibodies, that conditionally activate at optimal exposure levels, exhibit high potency, and possess ideal safety profiles Multiple clinical assets demonstrating differentiated CAB technology and strong results for challenging targets, leading to novel therapeutics that can fulfill previously unmet patient needs, and resulting in a broad and diverse pipeline Strong intellectual property foundation that provides worldwide coverage and multiple diversified patents for each product bicatla Talented and experienced management team, with a strong track record and over 20 years of experience on average with leading biopharmaceutical companies Strong financial support through a global collaboration with BeiGene and backing of reputable investors such as Pfizer Ventures, Soleus Capital, and HBM Healthcare Investments 30#31www.BioAtla.com bicatla