BioAtla IPO Presentation Deck

Tumor volume (mm³) CAB-EpCAM x CAB-CD3 Bispecific Antibody Exhibits Comparable Results, While Maintaining Superior Safety Profile bicatla Commentary IL-6 (pg/mL) CAB EpCAM bispecific demonstrates tumor shrinkage 2500 2000 1500 1000 500 0 2000 1500 1000 CAB EpCAM exhibits lower IL-6 levels 600 400 200 5 0 -Vehicle -EpCAM x WT CD3 CAB EDCAM x CAB CD3 -Isotype x WT CD3 20 Study days Xenograft Model with HCT116= Colorectal Cancer Cell Line 2.5mg/kg twice/week in mice (roughly equivalent to 0.2mg/kg in non-human primates) 10 15 0.05mg/kg 25 EpCAM x WT CD3 EpCAM x CAB CD3 BF3 30 35 • CAB EpCAM bispecific antibodies have long lives and maintained comparable results to non-CAB bispecific antibodies . Low toxicity observed and lower levels of IL-6, an inflammatory cytokine, after treatment with EpCAM x CAB-CD3 vs EPCAM x WT-CD3 antibody Non-CAB EpCAM Bispecific Safety Results Non-human Primates 0.25mg/kg = 2 expired 0.05mg/kg = 1 expired; 1 ill (recovered) 0.025mg/kg = 2 ill (recovered) * Marked increase in ALP, ALT, AST, TBIL, CK were noted, with Gl and kidney function impacted * Hepatocellular and cholestatic injury was identified CAB EpCAM Bispecific Safety Results Non-human Primates 0.25mg/kg = 1 healthy; 1 ill (recovered) 0.05mg/kg = 2 healthy 0.025mg/kg = 2 normal ✓ Only high doses create early signs of toxicity Low toxicity observed at the lower doses Lower levels of IL-6 generated and no deaths 26

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