BioAtla IPO Presentation Deck

BA3011: Encouraging Results in AXL High (TmPS 270) Sarcoma Patients at 1.8mg/kg Sarcoma (confirmed TmPS** 270; 1.8mg/kg Q3W or 2Q3W) Maximum % Change from Baseline in Sum of Target Lesions 100 80 -40 -80 -100 AXL+ TmPS-90¹1 I 1.8mg/kg d1,8 Tumor may not accurately represent AXL. expression at time of treatment due to outdated age of tissue sample AXL+ TmPS=100 1.8mg/kg d1,8 Leiomyosarcoma Uterine I (LMS) LMS TmPS-90 1.8mg/kg LMS (NED") * Confirmed Partial Response (PR) Out of 61 sarcoma patients screened for AXL Tumor Membrane Expression: • 35 had a TmPS ≥ 70 (57%) AXL+ TmPS=70 1.8mg/kg d1,8 UPS Patient case study on right side AXL+ TmPS-95 1.8mg/kg d1,8 UPS AXL+ TmPS-100 1.8mg/kg Ewing 4 partial responses out of 6 for sarcoma patients with TmPS 270 at the optimal dosing levels Note: "AXL Tumor membrane Percent Score or TmPS = % Score 21+ *Tissue biopsy from resection, over 1 year old prior to trial entry All patients: Multiple cycles of antineoplastic agents received prior to starting treatment with BA3011; INED = No evidence of disease bicatla LMS Patient Case Study Pre-treatment Post-treatment, week 18 Scan 37% tumor reduction . Tumor mass reduced enough to enable successful surgical resection resulting in NED¹ 12

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