BioAtla Investor Presentation Deck

Undifferentiated Pleomorphic Sarcoma (UPS): Phase 1 & 2 Change in Target Lesion and Progression Free Survival (1.8mg/kg; n=10) 100 80 60 40 20 ■ -20 -40 -60 -80 -100 Baseline Week 6 Change Target Lesion From Baseline (%) Week 12 Week 20 Week 28 Week 36 Combo Week 44 Week 52 Week 60 Interim data- Data cut-off of Oct 17, 2022 Week 68 Week 76 Week 84 Week 92 Week 100 Week 108 1.0 0.8- 0.6 0.4 0.2- 0.0- T T 0 1 2 3 Number at Risk All Patients 10 10 8 4 4 5 4 Progression-free Survival All Patients 6 7 Combined Phase 1 & 2: enrolled = 10; efficacy evaluable = 8; on-going with 1 scan = 2 4/8 patients achieved PRs, with an ORR of 50% and PFS rate at 3 months of 50% Responses to BA3011 treatment are durable, with partial responders remaining on treatment for extended periods of time Interim results satisfied the pre-defined Go criteria of UPS cohort into part 2 of the Phase 2 study bicatla 8 9 4 4 3 3 Events n(%) 7(70.0) 10 11 12 13 Median (mos) (95% CI) 6.8 (1.4 - NE) 14 15 16 17 18 Months from First Dose 33 2 2 2 2 1 1 1 1 19 1 20 1 PFS 3mo % (95%CI) 50.0 (18.4, 75.3) 21 22 23 24 1 1 0 BioAtla| Overview 12

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