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=105) Combination with PD-1 (n=20) bicatla Phase 2 Part 1 STS Bone CD20 (BA3011 + Opdivo) Leiomyosarcoma (n=18)* Synovial sarcoma (n=5)* Liposarcoma (n=6)* Other Soft Tissue / UPS (n=17/8)* Osteosarcoma (n=6)* Ewing sarcoma (n=2)* Others (chondro/chordo) (n=8 [5/ 3])* CD 20 Positive (n=14)* CD 20 Negative (n=10)* Interim Results Leiomyosarcoma; PFS rate 12W 32% Synovial PFS rate 12W 50% Liposarcoma PFS rate 12W 60% UPS PR = 2/6 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) 40% Combo w/ PD-1, CD 20-; PFS rate 12W 16.7% Cohorts in gray continue to interim read-out Advance P2 Part 2 Hold Evaluating Evaluating Go Go III Hold No Go 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%. * As of data cut-off Jul 25, 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. Interim results satisfied pre- defined 'Go' criteria into part 2 of the Phase 2 BA3011 study in multiple sarcoma subtypes: UPS and osteosarcoma advancing as separate cohorts to potentially registration studies (Phase 2 part 2). Additional detail for part 2 ● ■ will become available following FDA written response Liposarcoma and synovial sarcoma next steps under evaluation BioAtla| Overview 11

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