BioAtla Investor Presentation Deck

Potential market opportunity in UPS and Osteosarcoma 2nd most common Soft Tissue Sarcoma (STS) subtype (~15% of all STS)¹ UPS Osteosarcoma bicatla 1 2 3 1 2 3 High-grade aggressive subtype with high recurrence rates¹ 3k 4k AXL+ addressable patients per year in the U.S.1,4 Most common malignant primary bone tumor (30% of all such malignancies)² ~20% of patients have metastases at diagnosis; of the remainder, 50% progress to clinical metastasis³ 2k 3k AXL+ addressable patients per year in the U.S.2-4 - - - - Chemotherapy, chemoradiation or regional limb therapy for unresectable cases No approved targeted therapies for UPS Approved treatments for sarcoma ORR ~15%5 Current Treatments ¹Undifferentiated Pleomorphic Sarcoma - StatPearls - NCBI Bookshelf (nih.gov); Annals of Oncology 30: 1143-1153, 2019. ²https://www.cancernetwork.com/view/bone-sarcomas. 3https://www.cancer.org/cancer/osteosarcoma/detection-diagnosis-staging/staging.html; 1st-line surgical resection +/- chemo / radiation No approved therapies for 2L+ Independent Phase 2 study showed PFS rate for placebo at 8 weeks = ~0%6 https://www.texasoncology.com/types-of-cancer/bone-cancer/osteosarcoma- overview/recurrent-osteosarcoma. 4Company estimates 5Product USPIs. "Lancel Oncol 2019 Jan;20(1):120-133. 2L, second line; 2L+, second line or greater; ORR, objective response rate (best objective response as confirmed complete response or partial response); PBO, placebo; STS, soft tissue sarcoma; UPS, undifferentiated pleomorphic sarcoma. Current Treatments BioAtla| Overview 9

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