BioAtla IPO Presentation Deck

BA3011 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

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