BioAtla Investor Presentation Deck

Phase 2, part 1 topline interim analysis results confirm Phase 1 signal following BA3011 in refractory sarcoma subtypes BA3011 Monotherapy (n=78) Combination with PD-1 (n=26) bicatla Phase 2, Part 1 STS Bone CD20 (BA3011 + Opdivo) Leiomyosarcoma (n=19)* Synovial sarcoma (n=5)* Liposarcoma (n=8)* Other Soft Tissue / UPS (n=18/8)* Osteosarcoma (n=8)* Ewing sarcoma (n=9)* Others (chondro/chordo) (n=11 [6/ 3])* CD 20 Positive (n=14)* CD 20 Negative (n=12)* Interim Results Leiomyosarcoma; Enrolling 3Q4W Synovial PFS rate 12W 54% Liposarcoma PFS rate 12W 67% UPS Enrolling 3Q4W Osteosarcoma; PFS rate 12W 67% Ewing sarcoma Pending Others (chondro/chordo) Pending Combo w/ PD-1; PR = 1/1 (UPS)** & PFS rate 12W (combo overall) 32% Combo w/ PD-1, 1 PR (LMS); PFS rate 12W 31% Cohorts in gray continue to interim read-out Advance Phase 2, Part 2 Evaluating Go - Label Expansion Go - Label Expansion Go - Initial Indication Go - Label Expansion 1 Not advancing Not advancing Interim results satisfied pre-defined 'Go' criteria into part 2 of the Phase 2 BA3011 study in multiple sarcoma subtypes: UPS - clear guidance from FDA, enrolling phase 2, part 2 as initial indication Osteosarcoma, liposarcoma and synovial - pursue registration post UPS approval Pre-defined criteria for each subgroup up to 10 patients: 'No Go' if 0 CR/PR and PFS rate at 3 months <40%; 'Go' if ≥1 CR/PR or PFS rate at 3 months >40%. * enrollment as of Feb 28, 2022; Cohorts in gray continuing enrollment until sufficient sample size is achieved. **Included in UPS cohort. BA3011 dose 1.8 mg/kg Q2W. PFS, progression-free survival; PR, partial response; UPS, undifferentiated pleomorphic sarcoma. BioAtla| Overview 14

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