BioAtla Investor Presentation Deck

CAB-CTLA-4 (BA3071) - Phase 1 Dose Titration Ongoing 3 patients dosed at 700 mg Q3W in combination with nivolumab Cancer Type Renal cell Gastro-esophageal NSCLC Age Prior Tx bicatla 78 66 76 5 4 7 Adverse Events G1 fever and chills; G2 transient hypoxia G1 fever and chills G1 fever and chills; G2 transient hypoxia No No DLT Yes (atrial fibrillation) Cycles Completed 6 2 2 Overall Response SD SD SD Disposition Ongoing DC-Subject Decision DC-AE • Renal cell patient commenced prophylactic tocilizumab cycle 4 onward, now post 6 cycles and tolerating continued therapy • Further evaluation of 700 mg and potentially 1000 mg both with prophylactic tocilizumab BioAtla| Overview 21

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