BioAtla Investor Presentation Deck

Continued 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

View entire presentation