BioAtla Investor Presentation Deck

Encouraging Phase 1 results with Mecbotamab Vedotin (BA3011) in refractory sarcoma ■ Confirmed TmPS* ≥70; 1.8mg/kg Q3W or 2Q3W Maximum % Change from Baseline in Sum of Target Lesions 100 80 60 40 20 -20 -40 -60 -80 -100 AXL+ TmPS-90$ bicatla 1.8mg/kg d1,8 Leiomyosarcoma (LMS) AXL+ TmPS=100 1.8mg/kg d1,8 Synovial² Sarcoma AXL+ TmPS=100 1.8mg/kg d1,8 Uterine LMS r Confirmed Partial Response (PR) AXL+ TmPS-90 1.8mg/kg LMS * (NED¹) AXL+ TmPS-95 1.8mg/kg d1,8 UPS AXL+ TmPS-70 1.8mg/kg d1,8 UPS AXL+ TmPS=100 1.8mg/kg Ewing I Change in Target Lesion from Baseline (%) Evaluable Patients in Phase 1 at All Doses 100 80 60 40 20 -20 -40 -60 -80 -100 0 10 Notes: All patients: Multiple cycles of antineoplastic agents received prior to starting treatment with BA3011 *AXL Tumor membrane Percent Score or TmPS = % Score 21+; $Tissue biopsy from resection, over 1 year old prior to trial entry 1 NED = No evidence of disease; 2 Synovial sarcoma patient delayed treatment due to unrelated SAE led to progression 20 = PR was achieved in 4/7 high TmPS patients receiving the clinically-meaningful 1.8 mg/kg dose Antitumor activity correlates with higher levels of AXL tumor membrane expression in sarcoma patients 30 High TmPS ≥70 Low TmPS ≤70 or Not Evaluable 40 Time (weeks) 50 60 70 BioAtla| Overview 10

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