BioAtla Provides Clinical Program Updates and Upcoming 2023 Milestones

• Mecbotamab vedotin (BA3011) Phase 2 part 1 interim results in PD-1 failure NSCLC continues to show strong antitumor activity in a highly refractory population with additional patients enrolled

• BA3011 Undifferentiated Pleomorphic Sarcoma (UPS) Phase 2 part 2 of the potentially registrational study is being initiated; anticipate first patient dosed this quarter

• BA3071 Phase 1 study ongoing with first two dose escalation cohorts completed; third cohort (70mg) on-going

• CAB clinical programs continue to progress with multiple significant inflection points expected in 2023

SAN DIEGO, Jan. 10, 2023 (GLOBE NEWSWIRE) — BioAtla, Inc. (Nasdaq: BCAB), a global clinical-stage biotechnology company focused on the development of Conditionally Active Biologic (CAB) antibody therapeutics for the treatment of solid tumors, today announced its recent accomplishments for its clinical pipeline and provided upcoming 2023 milestones. Company updates and 2023 milestones will be presented in a fireside chat at 41^st Annual J.P. Morgan Healthcare Conference, January 10, 2023.

“BioAtla made significant progress and growth in 2022 and we continue to see encouraging data from both our preclinical and clinical studies. We anticipate 2023 as a promising year ahead with important milestones from multiple clinical programs,” said Jay M. Short, Ph.D., Chairman, Chief Executive Officer and co-founder of BioAtla, Inc.

“We are excited with the continued antitumor activity and differentiated safety profile of BA3011, particularly as monotherapy in PD-1-refractory NSCLC patients in our ongoing part 1 of the phase 2 study,” said Scott Smith, President of BioAtla. He continued, “We also remain encouraged with the progress we have made in our Phase 2 part 2 UPS study and BA3071 CAB-CTLA-4 Phase 1 study. Our solid cash runway funds us into 2025, seeing us through to multiple value-generating milestones as we continue to execute and pursue indications with the highest unmet medical need that have significant impact for patients and our shareholders worldwide.”

Clinical Program Updates

• Phase 2 Trial of Mecbotamab Vedotin (BA3011, NCT03425279) in Patients with:
  • AXL-positive NSCLC
    • Part 1 of the trial ongoing in patients who have previously experienced failure of PD-1/L1, EGFR, or ALK inhibitor therapy (average failure 3 lines of therapy)
    • 29 patients enrolled to date (as of January 2023)
      • 20 efficacy-evaluable patients (18 in the non-squamous adenocarcinoma group and 2 in the squamous cell carcinoma group)
        • In the non-squamous group, 10 of 18 had monotherapy and 8 of 18 had combination therapy with nivolumab
      • All CR / PRs observed were in the non-squamous group
        • 4 PRs were in the monotherapy group (4 of 10, ORR 40%)
        • 4 PRs were in the monotherapy PD-1 failure group (4 of 9, ORR 44%)
        • 1 CR in combination therapy, (1 of 8, ORR 12.5%)
    • Following BA3011 in both monotherapy and in combination with nivolumab in advanced NSCLC patients, the safety profile continues to be differentiated, with no new safety signals observed
  • AXL-positive Soft Tissue and Primary Bone Sarcomas
    • Following FDA feedback to the proposed Phase 2 part 2 of the potentially registrational sarcoma study, protocol for UPS study design, including primary endpoint and size of study, finalized and the study is being initiated.
    • Part 1 of the Phase 2 study:
      • Study is progressing with continued efficacy in UPS with 50.0% PFS at 12 weeks (n=10 patients)
      • Study ongoing in patients with liposarcoma, synovial sarcoma, and osteosarcoma with continued, encouraging PFS at 12 weeks
        • Liposarcoma – 66.7% PFS (n=8)
        • Synovial sarcoma – 53.5% PFS (n=5)
        • Osteosarcoma – 66.7% PFS (n=7)
    • In refractory sarcomas, BA3011 in both monotherapy and in combination with nivolumab is generally well-tolerated with no new safety signals observed
• Phase 1/2 Dose-Escalation Trial of CAB-CTLA-4 (BA3071) Across Multiple Solid Tumor Types responsive to CTLA-4
  • Trial ongoing with two of three cohorts completed without any DLTs or SAEs reported

Expected Timing for Key 2023 Milestones

• 1H23
  • Phase 2 study of mecbotamab vedotin (BA3011, NCT03425279) in patients with AXL-positive NSCLC
    • Initiating preparations for discussions with the FDA regarding the potentially registrational part 2 of the study in AXL-positive NSCLC patients.
    • Submission of Phase 2 part 1 interim data for presentation at ASCO
  • First patient dosed in Phase 2 part 2 study in AXL-positive UPS patients
  • Interim data in the Phase 2 part 1 ROR-2 positive NSCLC study
  • CAB-EpCAM x CAB-CD3 TCE (BA3182) Phase 1 study initiation
• 2H23
  • Phase 2 part 2 of the BA3011 study in NSCLC patients anticipated initiation
  • Interim data in the Phase 2 part 1 ROR-2 positive melanoma study
  • Interim data in the Phase 2 part 1 ROR-2 positive SCCHN study
  • Phase 1 data and Phase 2 initiation in CAB-CTLA-4 (BA3071) study

About BioAtla^®, Inc.
BioAtla is a global clinical-stage biotechnology company with operations in San Diego, California, and in Beijing, China through our contractual relationship with BioDuro-Sundia, a provider of preclinical development services. Utilizing its proprietary Conditionally Active Biologics (CAB) technology, BioAtla develops novel, reversibly active monoclonal antibody and other protein therapeutic product candidates. CAB product candidates are designed to have more selective targeting, greater efficacy with lower toxicity, and more cost-efficient and predictable manufacturing than traditional antibodies. BioAtla has extensive and worldwide patent coverage for its CAB technology and products with 704 patents (430 issued, 5 allowed, and 269 pending). Broad patent coverage in all major markets include methods of making, screening and manufacturing CAB product candidates in a wide range of formats and composition of matter coverage for specific products. BioAtla has two first-in-class CAB programs currently in Phase 2 clinical testing in the United States, mecbotamab vedotin, BA3011, a novel conditionally active AXL-targeted antibody-drug conjugate (CAB-AXL-ADC), and ozuriftamab vedotin, BA3021, a novel conditionally active ROR2-targeted antibody-drug conjugate (CAB-ROR2-ADC). The Phase 1 stage CAB-CTLA-4 antibody, BA3071, is a novel CTLA-4 inhibitor designed to reduce systemic toxicity and potentially enable safer combination therapies with checkpoint inhibitors such as anti-PD-1 antibody. To learn more about BioAtla, Inc. visit www.bioatla.com.

Forward-looking statements
Statements in this press release contain “forward-looking statements” that are subject to substantial risks and uncertainties. Forward-looking statements contained in this press release may be identified by the use of words such as “anticipate,” “expect,” “believe,” “will,” “may,” “should,” “estimate,” “project,” “outlook,” “forecast” or other similar words. Examples of forward-looking statements include, among others, statements we make regarding our business plans and prospects, including whether our clinical trials will support registration; results, conduct, progress and timing of our research and development programs and clinical trials; expectations with respect to enrollment and dosing in our clinical trials, plans regarding future data updates, clinical trials, regulatory meetings and regulatory submissions; the potential regulatory approval path for our product candidates; expectations about the sufficiency of our cash and cash equivalents; and expected R&D and G&A expenses. Forward-looking statements are based on BioAtla’s current expectations and are subject to inherent uncertainties, risks and assumptions, many of which are beyond our control, difficult to predict and could cause actual results to differ materially from what we expect. Further, certain forward-looking statements are based on assumptions as to future events that may not prove to be accurate. Factors that could cause actual results to differ include, among others: potential delays in clinical and pre-clinical trials due to the global COVID-19 pandemic; other potential adverse impacts due to the global COVID-19 pandemic such as delays in regulatory review, manufacturing and supply chain interruptions, adverse effects on healthcare systems and disruption of the global economy; the uncertainties inherent in research and development, including the ability to meet anticipated clinical endpoints, commencement and/or completion dates for clinical trials, regulatory submission dates, or regulatory approval dates, as well as the possibility of unfavorable new clinical data and further analyses of existing clinical data; whether regulatory authorities will be satisfied with the design of and results from the clinical studies or take favorable regulatory actions based on results from the clinical studies; our dependence on the success of our CAB technology platform; our ability to enroll patients in our ongoing and future clinical trials; the success of our current and future collaborations with third parties; our reliance on third parties for the manufacture and supply of our product candidates for clinical trials; our reliance on third parties to conduct our clinical trials and some aspects of our research and preclinical testing; and those other risks and uncertainties described in the section titled “Risk Factors” in our Annual Report on Form 10-K filed with the Securities and Exchange Commission (SEC) on February 28, 2022 and in our Quarterly Reports on Form 10-Q filed with the SEC on May 5, 2022, August 9, 2022 and November 4, 2022 and our other reports as filed with the SEC. Forward-looking statements contained in this press release are made as of this date, and BioAtla undertakes no duty to update such information except as required under applicable law.

Internal Contact:
Richard Waldron
Chief Financial Officer
BioAtla, Inc.
rwaldron@bioatla.com
858.356.8945
External Contact:
Bruce Mackle
LifeSci Advisors, LLC
bmackle@lifesciadvisors.com