BioAtla IPO Presentation Deck

CABS Bind Selectively and Reversibly Based on the TME, Enhancing Exposure and Reducing Toxicity CABS Bind Selectively in the Lower pH TME CAB and Affinity Matched (AM) non-CAB AXL mAbs 2.5- ELISA Data OD450nm 1.5- Ab-ADC (ng/mL) 1.0- 0.5- 0.0- 5.5 10000 1000 Enhanced ADC Therapeutic Exposure AXL ADCs-1mg/kg dose 100 6.0 6.5 7.0 pH value 10 Blood 50 Non-CAB CAB 7.4 is pH of normal cell 150 100 Time (Hours) • CAB improves pharmacokinetics by eliminating TMDD CAB-ADC male CAB-ADC female 200 AM-ADC male AM-ADC female Selective Binding Reduced ADC Toxicity ALT (u/L) 1500 1000- Focused Tumor Killing 500- Pre- Treatment Post- Treatment bicatla Normal Cells Preserved AM Non-CAB AXL-ADC CAB AXL-ADC Day -3 Day 3 Study Day . CAB ADC resulted in minimal increase in ALT, supporting that on- target, off-tumor toxicity is reduced with the CAB ADC Unlike prodrugs, CABS are reversible, enhancing the therapeutic index Note: OD450nm = optical density measurements using a microplate reader with a 450nm filter: TME = Tumor Micro Environment; mABs = monoclonal antibodies; Data above based on non-human primate studies; AM= affinity matched, ALT or alanine aminotransferase is a sign of liver toxicity; TMDD = Tissue Mediated Drug Deposition

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