BioAtla Results Presentation Deck

Continued Promising Safety and Tolerability Profile in Phase 2 at the RP2D PHASE 2 AEs Overview ■ ■ ■ AEs consistent with MMAE-based toxicity, including: Reversible myelosuppression Transient liver enzyme elevation Metabolic disturbances Few related SAEs Few related AEs leading to treatment discontinuation Mecbo - BA3011 CAB AXL-ADC Dosing 1.8mg/kg Q2W (safety population Phase 2) Characteristic Any Adverse Events (AES) Related AEs with CTCAE¹ Grade 3 or 4²2 Any related serious AEs² Related AEs leading to death² Related AEs leading to treatment discontinuation² BA3011 (N=68) 61 (90%) 16 (23%) 6 (9%) Mecbo - BA3011 Peripheral Neuropathy ● Constipation ● Constipation is believed to be an on-target mediated effect Diarrhea Grade 1-2 (18%) Grade 3-4 (0%) All Grade 1-2 (23%) Grade 1-2 (19%) Grade 3-4 (0%) bicatla No clinically meaningful on-target toxicity observed over background Differentiated profile due to advantageous pharmacokinetic characteristics of CAB ADCs 2 (3%) Note: 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 Interim data- Data cut-off of March 31, 2022 8

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