Exhibit 99.1 TRANSFORMING CANCER THERAPY April 2022 Needham & Co Annual Healthcare Conference 1 `

Important 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 Annual Report on Form 10-K. 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. 2

© BioAtla is a clinical-stage biotech company focused on transforming cancer therapy with Conditionally Active Biologics (CABs) THE COMPANY TECHNOLOGY CLINICAL & TEAM FINANCE & INFRASTRUCTURE Proprietary CAB technology that Broad clinical and development Building on successful 2020 IPO, conditionally and reversibly bind to pipeline with two 1st-in-class P2 over $290MM in gross proceeds, cancer cells, but not to normal CAB-ADCs for multiple indications (including $75.0 MM raised 9/21). cells, enabling increased antibody and CAB-CTLA-4 initiated P1 clinical $245MM cash at EOY 2021 funds potency and reduced toxicity studies operations into 2024 Strong intellectual property rights: Headquartered in San Diego in a - 621 patents (360 issued, 9 Over 60 employees with exceptional ~43,000 square foot office and lab allowed, and 252 pending) experience in innovative research facility with a contract lab in and clinical development Beijing 3

Tumor cell acidity enables selective, reversible CAB binding via the novel TM* physiological-occurring PaCS molecule mechanism THE TECHNOLOGY In Acidic Cancer Cell Membranes In Alkaline Healthy Cell Membranes… BioAtla CAB antibodies In normal tissue (+) charged In the acidic TME the PaCS selectively target these (+) 1 amino acid residues shield 3 molecules are neutralized protein targets from drug by H+, exposing targets to charged amino acids on The Warburg Effect attack by binding to (-) drug attack. With no targets only available in the TM charged PaCS molecules. requirement for activation. acidic TME. Cancer cells divide rapidly, 2 requiring high rates of glycolysis**, resulting in an acidic TME (pH 5.8-6.7). + H + H + H Binding + H + H + H + H + H TM *PaCS = Protein-associated Chemical Switches **Glycolysis underpins the success of PET scanning 4 Prodrugs and masked antibodies require activation. Once activated, they cannot become inactive circulating from diseased to normal tissues. 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..

Leveraging advantages of CAB technology Anticipated advantages of CAB technology Examples of CAB technology’s broad application Improved safety and efficacy Targeting CTLA4 1 (BA3071 – Naked Antibody) Enhanced pharmacologic properties Targeting EpCAM x CD3 2 (BA3182 – Bispecific) Develop therapeutics against validated pathways Targeting Nectin-4 3 Expand target universe nd ¥ (BA3361 – 2 Gen ADC ) ¥ 2nd Gen ADC features complementing CAB Technology: Enable differentiated combination and 1. conjugation without sequence modification of antibody at DAR 4 and higher bispecific immuno-oncology therapies 2. high serum stability and high solubility with sugar-based linker 3. cleavage only in the lysosome with potential to reduce risk of neutropenia and neuropathy 5

BA3071 (CAB-CTLA4): best-in-class and potential for disruption of the I/O Market Nivolumimab Nivolumimab (PD-1) + Research demonstrates challenges and Clinical Endpoint (PD-1) Ipilumimab (CTLA4) opportunity in combining two Immune Progression Free Survival 6.9 months 11.5 months Checkpoint Inhibitors* Grade 3 or 4 Adverse 16.3% 55.0% • Improves efficacy, but increases adverse events Events • Greater % of patients discontinue therapy relative Discontinued Treatment 7.7% 36.4% to monotherapy Vehicle Control In NHP study, BA3071 achieved similar Nivo + Ipi exposure levels to Ipi analog with significantly Positive Control less toxicity in combination with nivo** Nivo + CAB- GI Symptoms BA3071 Liquid feces Non-formed feces Other GI symptoms *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) 6 Once weekly for four weeks exposure to Nivo + Ipi or CAB CTLA4

CAB-EpCAM x CAB-CD3 bispecific antibody exhibits comparable tumor shrinkage with superior safety profile CAB EpCAM x CAB CD3 bispecific Dual selection results in high selectivity demonstrates efficient tumor shrinkage Tumor Cell Target CAB-EpCAM CAB-CD3 T Cell Target Bispecific Safety Results (Non-GLP; Non-human Primates) MiXeno Model with HCT116 = Colorectal Cancer Cell Line WT-EpCAM x WT-CD3 1mg/kg twice/week in mice CAB-EpCAM x CAB-CD3 (BA3182) (equivalent to 0.25mg/kg in non-human primates) *0.25mg/kg = 2 normal *0.025mg/kg = 2 ill *1.0 mg/kg = 2 normal *0.05 mg/kg = 2 expired *2.5 mg/kg = 2 normal *2.5 mg/kg = 10 normal *5.0 mg/kg = 10 normal • >160x higher therapeutic index *Single Dose – non-GLP Toxicity Study *QW x 4 weeks – GLP Toxicity Study • MTD not yet reached WT = wild type; *from independent experiments MTD = Maximum Tolerated Dose 7 3 Tumor volume (mm )

Robust pipeline of differentiated CAB assets designed to deliver near-, mid- and long-term value IND Enabling Phase 1 Phase 2 Program Target Lead Indications Pre-Clinical Clinical BA3011 ✓ STS & Bone Sarcoma ✓ NSCLC (Mono & Combo w/ PD-1) Mecbotamab Vedotin AXL ✓ Ovarian Cancer* ✓ NSCLC BA3021 ✓ Melanoma (Mono & Combo w/ PD-1) ROR2 ✓ HNC Ozuriftamab Vedotin ✓ Ovarian Cancer* ▪ RCC▪ Bladder BA3071 ▪ NSCLC / SCLC▪ Gastric CTLA-4 ▪ HCC▪ Cervical Cancer Naked Antibody ▪ Melanoma (Mono & Combo w/ PD-1) ▪ Colorectal BA3182▪ Prostate Cancer** ▪ NSCLC / SCLC EpCAM & CD3 ▪ TNBC Bispecific ▪ Ovarian ▪ HNC▪ Pancreatic BA3142 ▪ Melanoma▪ Prostate Cancer** B7-H3 & CD3 Bispecific ▪ NSCLC / SCLC▪ Sarcoma ▪ Colorectal Cancer** BA3361▪ Pancreatic ▪ HNC Nectin-4 nd ▪ TNBC 2 Gen ADC ▪ NSCLC ▪ Breast BA3151 ▪ Ovary ▪ Colon B7-H4 nd▪ Prostate 2 Gen ADC ▪ Kidney ▪ Bladder BA3311 ▪ Pancreatic Cancer** EGFR & CD3 Bispecific ▪ TNBC 8 * Ph2 investigator-initiated trial for Ovarian Cancer ** Anticipated indications based upon tumor target expression Abbreviations: STS = Soft Tissue Sarcoma, NSCLC = Non-small Cell Lung Cancer, RCC = Renal Cell Carcinoma, SCLC = Small Cell Lung Cancer, HCC = Hepatocellular Carcinoma, TNBC = Triple-Negative Breast Cancer, HNC = Head and Neck Cancer

Strong execution and compounding momentum through 2021 2021 LOOKBACK Initiated four Phase 2 Entered into clinical potentially collaboration with BMS to Secured $75m registration-enabling evaluate two CAB-ADCs in through private ® studies across two combination with Opdivo placement different assets ✓ Mecbotamab Vedotin (AXL BA3011) Initiated CAB-CTLA4 ✓ Ozuriftamab Vedotin (ROR2 BA3021) Presented Phase 1 (BA3071) Phase 1 trial data in refractory sarcoma patients for Advanced two CAB- Mecbotamab Vedotin bispecific antibodies nd (BA3011) at CTOS and two 2 Gen ADCs to IND enabling studies 9

Four potentially registration-enabling Phase 2 trials ongoing with lead CAB-ADCs, Mecbotamab Vedotin & Ozuriftamab Vedotin Trial Status (Feb. ‘22) # PHASE 2 Sarcoma (STS & Bone) 26 sites activated Ongoing mono & combo w/ PD-1; AXL TmPS*≥50 & ≥70 70 pts fully enrolled rd 3 Line (n=200-275) Mecbo – BA3011 NSCLC 42 sites activated mono & combo w/ PD-1; AXL TmPS*≥50 Actively dosing in PD-1, EGFR or ALK failure patients (n=40) Melanoma 16 sites activated Actively dosing mono & combination w/ PD-1; ROR2 positive ROR2 TmPS*≥ 1; PD1 failure patients (n=200) Ozurif – BA3021 39 sites activated NSCLC Actively dosing mono & combination w/ PD-1; ROR2 positive ROR2 TmPS*≥ 1; PD1, EGFR or ALK patients (n=200) Initiated Head & Neck (SCCHN) Initial sites activated, mono & combination w/ PD-1 (n=80-100); ROR2 positive Ozurif – BA3021 dosing 1H 2022 ROR2 TmPS*≥ 1; Platinum or PD-1 failure patients Ovarian (Investigator-Initiated Trial) Initial sites activated, BA3011 & BA3021 combination w/ PD-1 (n=60); ROR2 positive dosing 1H 2022 ROR2 TmPS*≥ 1; Platinum failure patients 10 # Note: STS = Soft Tissue Sarcoma; *TmPS= Tumor membrane Percent Score- Scores range from 0 to 100

Significant opportunity to fill treatment void in sarcomas Mecbo – BA3011 SARCOMA Unmet Need for Sarcomas Large and Under-Appreciated ✓ No targeted therapies available for most soft tissue Commercial Opportunity sarcoma ✓ Bone sarcomas have no approved therapies after failure of frontline regimens ✓ Low 5-year survival rates (~16.4% for late-stage • ~17,000 diagnosed unresectable / metastatic cases in 2021 metastatic soft tissue sarcoma) • Before withdrawal from market for failing Phase 3, Lilly’s olaratumab had sales of $562 million with a 50% CAGR, in less than 2 years Lower Regulatory Hurdles for Sarcoma Treatments 100% • Approved therapies show improved 75% 1 ORRs of less than 15% 50% 25% 15% * * * * * * * ORR 0% * Approved Source: DRG. Soft tissue sarcoma. Epi dashboard. 2020 1 Note: Objective response rates (ORR) is defined as the proportion of patients with tumor 5 size reduction of a predefined amount and for a minimum time period and is comprised of Median progression-free survival (PFS) for approved therapies ranges from 2 – 7 months 2 complete responses and partial responses; Pembrolizumab ORR data from 2015-2016 11 3 4 Pembrolizumab ORR data from 2017 ORR for Gemcitabine treatment in combination with 5 Docetaxel CA CANCER J CLIN 2020;70:200–229

Encouraging Phase I results with Mecbotamab Vedotin in refractory sarcoma Mecbo – BA3011 PHASE 1 - SARCOMA Confirmed TmPS* ≥70; 1.8mg/kg Q3W or 2Q3W Evaluable Patients in Phase 1 at All Doses High TmPS ≥70 AXL+ 100 Low TmPS ≤70 or Not Evaluable $ TmPS=90 1.8mg/kg 80 Confirmed Partial Response (PR) d1,8 60 AXL+ TmPS=100 40 1.8mg/kg AXL+ AXL+ AXL+ AXL+ AXL+ d1,8 TmPS=100 TmPS=90 TmPS=95 TmPS=70 TmPS=100 20 1.8mg/kg 1.8mg/kg 1.8mg/kg 1.8mg/kg 1.8mg/kg d1,8 d1,8 d1,8 0 2 Leiomyosarcoma Synovial Uterine (LMS) Sarcoma -20 LMS -40 LMS * -60 1 (NED ) UPS * -80 UPS * Ewing -100 * Notes: All patients: Multiple cycles of antineoplastic agents received prior to starting treatment with BA3011 $ *AXL Tumor membrane Percent Score or TmPS = % Score ≥1+; Tissue biopsy from resection, over 1 year old prior to trial entry 1 2 NED = No evidence of disease; Synovial sarcoma patient delayed treatment due to unrelated SAE led to progression 12 Maximum % Change from Baseline in Sum of Target Lesions

Predefined Interim Analysis: Decision Tree Mecbo – BA3011 PHASE 2 - SARCOMA ~10 patients w TmPS>=70 LMS Syn ~10 patients w TmPS>=70 STS Lipo For each Subgroup ~10 patients w TmPS>=70 up to 10 patients Others Monotherapy ~10 patients w TmPS>=70 No Go if 0 CR/PR and PFR12 week < 40% Osteo ~10 patients w TmPS>=70 Go if ≥ 1 CR/PR or Bone Ewing ~10 patients w TmPS>=70 PFR12 week ≥ 40% ~10 patients w TmPS>=70 Others ~10 patients w CD20 pos Combo with PD-1 ~10 patients w CD20 neg 13

Preliminary observations from Phase 2 sarcoma study with Mecbotamab Vedotin Mecbo – BA3011 PHASE 2 - SARCOMA • Study enrolling as per plan with initial interim cohort of ~70 pts enrolled at EOY • Reported good clinical activity in advanced refractory sarcoma population to date • Several cohorts already qualified to move into part 2 of the P2 study • Safety profile continues to be well-differentiated st • Full interim P2 study data cut made on March 31 w/ a targeted two scans per patient th • Clinical data analysis underway – topline interim update scheduled for May 4 earnings call • Patient enrollment expected to continue through upcoming P2 interim stage FDA discussions 14

Complete response in 1/1 ROR2+ patient in stage IV multi-refractory melanoma and partial response in 1/1 ROR2+ patient in head and neck squamous cell cancer (HNC) Ozurif – BA3021 Phase 1 - MELANOMA Two evaluable metastatic melanoma patients enrolled in Phase 1 trial 100 0.6 mg/kg (d1) 80 3.0 mg/kg (d1) 60 40 ROR2 - 20 0 -20 -40 -60 ROR2 + -80 -100 120 140 0 10 20 30 40 Time (weeks) Details: ROR+ Patient ✓ Prior treatment failure: nivolumab followed by nivolumab + ipilimumab combination achieved ✓ Melanoma confirmed by biopsy immediately prior to BA3021 trial entry Complete ✓ Clearance of pulmonary metastases followed by normalization of adenopathy Response ✓ Continued CR Off treatment for approximately one year Phase 1 - HEAD and NECK SQUAMOUS CELL CANCER (HNC): Additionally, Partial Response (-54%) observed in 1 / 1 ROR2 + (TmPS = 16%) HNC patient (refractory to four prior lines of therapy including cetuximab and pembrolizumab) 15 Change in target lesion from baseline (%) »

Encouraging Phase I results in NSCLC refractory patients Phase 1 - NSCLC Mecbo – BA3011 Ozurif – BA3021 Response at Variable Dosing Response at Variable Dosing 30% ROR2 + ROR2 – ROR2 + Not ROR2 + ROR2 + (**TmPS=100) (**TmPS=0) (**TmPS=45) Evaluable (**TmPS=95) (**TmPS=70) 1.2mg/kg d1,8 3mg/kg d1 3.3mg/kg d1 1.5mg/kg d1,8 3.3mg/kg d1 3mg/kg d1 20% 10% AXL – AXL – Not AXL + TmPS=0 TmPS=0 Evaluable TmPS=80 0% 1.5mg/kg d1,8 1.2mg/kg d1,8 1.2mg/kg d1 1.8mg/kg d1,8 PR -10% Suboptimal dose (1.2mg/kg 2Q3W) -20% • Patient experienced tumor shrinkage prior to -30% progression of metastatic * bone lesions Confirmed PR -40% Stage IV • NSCLC squamous tumor: adenocarcinoma 10mm to 0mm on first scan -50% (multiple chemo PKIs and * pembrolizumab failure) -60% Note: Not Evaluable (Strong, extensive fibroblastic stromal positivity reported) 16 Maximum Change from Baseline (%) Maximum % Change from Baseline in Sum of Target Lesions

Promising safety and tolerability profile emerging PHASE 1 AEs for all doses CAB AXL-ADC Mecbo – BA3011 (all patients n=64) Overview Grade 1-2 (26%) ▪ AEs consistent with MMAE-based toxicity, including: Constipation o Reversible myelosuppression Grade 3 (3%) o Transient liver enzyme elevation Peripheral Neuropathy o Metabolic disturbances All Grade 1-2 (28%) ▪ Few related SAEs Grade 1-2 (19%) ▪ Few related AEs leading to treatment discontinuation Diarrhea Grade 3-4 (3%) Constipation is believed to be an on-target mediated effect PHASE 1 & 2 AEs at P2-relevant doses • No clinically meaningful on-target toxicity observed over background CAB AXL-ADC Mecbo – BA3011 Dosing 1.8mg/kg Q3W, Q2W, or 2Q3W (d1,8) • Differentiated profile due to advantageous pharmacokinetic (safety population Phase 1 & 2) characteristics of CAB ADCs BA3011 Characteristic (N=38) Any Adverse Events (AEs) 38 ( 100%) 1 2 15 ( 39%) Related AEs with CTCAE Grade 3 or 4 2 Any related serious AEs 4 ( 11%) Ozurif – BA3021 2 0 Related AEs leading to death Related AEs leading to treatment • Similar safety profile observed § 2 (5%) 2 discontinuation 17 1 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 2 § grading (severity) scale is provided for each AE term. As assessed by the investigator. Missing responses are counted as related. Grade 2 fatigue and peripheral neuropathy at 1.8mg/kg 2Q3W

Many value-creating milestones in 2022 Key Clinical Updates Mecbotamab Vedotin (BA3011) Mecbotamab Vedotin (BA3011) NSCLC Ozuriftamab Vedotin (BA3021) Sarcoma Phase 2 Interim Update Phase 2 Interim Analysis (1H 2022); NSCLC and Melanoma Phase 2 (1Q earnings call – May 4, 2022) Interim Update (2Q earnings call) Interim Update (mid-year / 2H 2022) CAB-EpCAM x CAB-CD3 CAB-CTLA-4 (BA3071) bispecific (BA3182) IND Phase 1/2 Trial Dosing Submission and Phase 1 Clinical Advancements (H1 2022) initiation (H2 2022) Mecbotamab Vedotin Ozuriftamab Vedotin Mecbotamab Vedotin (BA3011) and Ozuriftamab (BA3021) Head and Neck (BA3011) Phase 2 Sarcoma Vedotin (BA-3021) Ovarian Cancer Phase 2 Trial Dosing Final Data (2023) IIT Dosing (H1 2022) (H1 2022) 18

2022 BioAtla corporate priorities Execute on clinical programs Create long-term sustainable value Create long-term sustainable value Build core commercial capabilities 19