NPDC1

Ozuriftamab vedotin (CAB-ROR2-ADC) granted Fast Track Designation by FDA in squamous cell carcinoma of the head and neck (SCCHN); anticipate FDA meeting for SCCHN potential registrational trial in 2H 2024Evalstotug (CAB-CTLA-4 antibody) demonstrated a similar low incidence and severity of immune-related adverse events across both Phase 1 and 2 studies; Phase 2 combination with pembrolizumab study continues to enroll and on track for initial data readout in 2H 2024Mecbotamab vedotin (CAB-AXL-ADC) Phase 2 trial in NSCLC showed trend for improved overall survival among treated patients with tumors expressing mutated KRAS variants compared to KRAS wildtype; anti-tumor activity across multiple KRAS mutation variants including G12A, G12C, and G12V Current cash balance projected to fund operations through Q3 2025 sufficient to deliver clinical readouts in multiple indications, position our programs for one or more potentially registrational trials, and enhance our position in advancing strategic collaboration discussions Management to host conference call and webcast today at 4:30 PM Eastern Time SAN DIEGO, Aug. 08, 2024 (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 financial results for the second quarter ended June 30, 2024, and provided highlights on its clinical programs. “BioAtla continues to execute across our CAB portfolio, highlighted by ongoing positive clinical responses and a potentially differentiated safety profile observed with our CAB Phase 2 assets,” said Jay M. Short, Ph.D., Chairman, Chief Executive Officer and co-founder of BioAtla, Inc. “We are pleased to receive Fast Track Designation for ozuriftamab vedotin in the treatment of recurrent or metastatic head and neck cancer and are on track to meet with the FDA this year. The clinical profile of evalstotug, in particular the low incidence and severity of immune-related AEs, supports a potentially best-in-class CTLA-4 antibody for the treatment of multiple solid tumors. Further, we are encouraged with the emerging clinical profile of mecbotamab vedotin in patients with NSCLC harboring KRAS mutation variants. The company remains well-positioned for multiple FDA meetings by year end to discuss potentially registrational trials while we continue to advance discussions with potential strategic partners.” Key Developments, Operational Updates and Upcoming Milestones Phase 2 Trials of ozuriftamab vedotin, CAB-ROR2-ADC in treatment-refractory SCCHN (NCT05271604) (median 3 prior lines of treatment) In the 29 evaluable patients to date, a total of 11 responses at the combined 2Q3W and Q2W dose regimens Fast Track Designation granted by FDAData to be presented at upcoming poster presentation at ESMO in September Phase 1/2 dose-escalation trial of evalstotug, CAB-CTLA-4 (NCT05180799) across multiple solid tumor types (median 3 prior lines of treatment) Phase 1 dose-escalation study evaluated evalstotug in combination with nivolumab in patients who experienced failure of prior PD1 treatment Confirmed responses (3/8) with evalstotug (350 mg) in combination with PD-1Patients treated with ≥350mg evalstotug received more doses (mean, 7.2) compared with reported ipilimumab (3.4) or tremelimumab (4.3); no dose reductions occuredMultiple patients on therapy without progression for >1 year Initial Phase 2 monotherapy data readout with two scans in treatment-refractory solid tumors at 350 mg (n=17) or 700 mg (n=2) (5 or 10 mg/kg for 70 kg person, respectively) to evaluate safety and immune-related adverse events Study ongoingAcross 14 different tumor types, 10 patients with stable disease following monotherapy treatment; multiple patients experienced prolonged PFS (>10 months) to date Combined Phase 1 and Phase 2 safety (n=40) demonstrated low rate of grade 3 immune-related adverse events (irAEs) (4/40); no related grade 4 or 5 events; incidence and severity of irAEs consistent across Phase 1 and Phase 2 studiesData to be presented as oral presentation at the Society for Melanoma Research Congress in October and a poster presentation at the Society for Immunotherapy of Cancer in NovemberPhase 2 first-line melanoma and first-line NSCLC patients at 700 mg (10 mg/kg for 70 kg person) in combination with pembrolizumab and in combination with pembrolizumab plus chemotherapy continues to enroll; on track for initial melanoma data readout in 2H 2024 Phase 2 trial of mecbotamab vedotin, CAB-AXL-ADC (NCT04681131) in NSCLC (median 3 prior lines of treatment) Additional expansion cohort (n=33) 2Q3W evaluating AXL expression, dose, subtype and safetySubgroup results: AXL expression ≥1% correlated with anti-tumor activity in both Q2W and 2Q3W dosing regimensAnti-tumor activity with multiple confirmed responses among patients with tumors expressing mutated KRAS: Overall survival benefit trend observed among treated patients whose tumors express mutated KRAS compared to those with wildtype KRAS genotypeResponses observed across patients with tumors expressing multiple KRAS mutation variants to date, including G12A, G12C, and G12VResponse observed in a patient whose tumor expressed a mutated KRAS G12C variant who had experienced prior failure of sotorasibOne patient treated in combination with PD-1 antibody remains in complete response for greater than 2 yearsmKRAS variants represent 30% of all NSCLC patients and is highly correlated with AXL expression Manageable safety continues with no new safety signals identified Phase 1/2 dose-escalation for CAB-EpCAM x CAB-CD3 TCE (BA3182, NCT05808634) Study is progressing and ongoing; on track for data readout of Phase 1 study in 2H 2024 Second Quarter 2024 Financial Results Research and development expenses were $16.2 million for the quarter ended June 30, 2024 compared to $31.0 million for the same quarter in 2023. The decrease of $14.8 million was primarily due to completion of pre-clinical development for our Nectin-4 ADC which received IND clearance in May 2024, and the impact of prioritization of our clinical programs in 2023 resulting in less expense for our pre-clinical programs in 2024. Our clinical program expense decreased related to completion of Phase 2 enrollment for our ongoing ADC trials for mecbotamab vedotin and ozuriftamab vedotin. We expect our R&D expenses to continue to decrease in the near-term as we complete our planned Phase 2 clinical trials and meet with the FDA to discuss potentially registrational trials for our Phase 2 programs. General and administrative expenses were $5.8 million for the quarter ended June 30, 2024 compared to $6.2 million for the same quarter in 2023. The $0.5 million decrease was primarily due to lower stock based compensation expense. Net loss for the quarter ended June 30, 2024 was $21.1 million compared to a net loss of $35.8 million for the same quarter in 2023. Net cash used in operating activities for the six months ended June 30, 2024 was $50.0 million compared to net cash used in operating activities of $46.7 million for the same period in 2023. Our cash used for the quarter ended June 30, 2024 was $19.0 million in line with guidance, compared to $30.8 million during the quarter ended March 31, 2024. Cash and cash equivalents as of June 30, 2024 were $61.7 million, compared to $111.5 million as of December 31, 2023. We expect current cash and cash equivalents to fund planned operations through Q3 of 2025 which is sufficient to deliver clinical readouts in multiple indications, position our programs for one or more potentially registrational trials, and enhance our position in advancing strategic collaboration discussions. Second Quarter 2024 Conference Call and Webcast Details The management of BioAtla, Inc. will host a conference call and webcast for the investment community today, August 8, 2024, at 4:30 pm Eastern Time. A live webcast may be accessed here: https://viavid.webcasts.com/starthere.jsp?ei=1677714&tp_key=f44f1624a8. The conference call can be accessed by dialing toll-free (800) 579-2543 (domestic) or (785) 424-1789 (international). The passcode for the conference call is BIOATLA. A replay of the webcast and slides with topline interim clinical data referenced on the call will be available through “Events & Presentations” in the Investors section of the company’s website after the conclusion of the presentation and will be archived on the BioAtla website for one year. About Ozuriftamab Vedotin (BA3021) Ozuriftamab vedotin, CAB-ROR2-ADC, is a conditionally and reversibly active antibody drug conjugate directed against ROR2, a transmembrane receptor tyrosine kinase that is present across many different solid tumors including head and neck, lung, TNBC and melanoma. Overexpression of ROR2, a noncanonical wnt5A signaling receptor, forms a cancer axis that is associated with poor prognosis and resistance to chemo- and immunotherapies. This Phase 2 stage clinical asset is targeting multiple solid tumor indications, including the treatment of SCCHN patients who have previously progressed on PD-1/L1 therapies with or without platinum chemotherapy. About Evalstotug (BA3071) Evalstotug, is a CAB anti-CTLA-4 antibody that is being developed as an immuno-oncology agent with the goal of delivering efficacy at least comparable to the approved anti-CTLA-4 antibodies, but with lower toxicities due to the CAB's tumor microenvironment-restricted activity. This may enable safer anti-CTLA-4 antibody combination therapies, such as with anti-PD-1 antibody checkpoint inhibitors, and potentially broaden the patient population tolerant to combination therapy and deliver greater efficacy. Like our other CAB candidates, this Phase 2 clinical asset is designed to be conditionally and reversibly active in the tumor microenvironment. Evalstotug is being developed as a potential therapeutic for multiple solid tumor indications that are known to be responsive to CTLA-4 treatment in combination with a PD-1 blocking agent. About Mecbotamab Vedotin (BA3011) Mecbotamab vedotin, CAB-AXL-ADC, is a conditionally and reversibly active antibody drug conjugate targeting the receptor tyrosine kinase AXL. This Phase 2 stage clinical asset is targeting multiple solid tumor indications, including the treatment of soft tissue and bone sarcoma and non-small cell lung cancer (NSCLC) patients who have previously progressed on PD-1/L1, EGFR or ALK inhibitor therapies. The Office of Orphan Products Development (OOPD) at FDA granted Orphan Drug Designation to mecbotamab vedotin for the treatment of soft tissue sarcoma. About CAB-EpCAM x CAB-CD3 Bispecific T-cell Engager Antibody (BA3182) BioAtla is developing BA3182 as a potential anticancer therapy for patients with advanced adenocarcinoma. BA3182 is a (CAB) EpCAM x (CAB) CD3 bispecific T cell engager antibody that contains two binding sites for EpCAM and two binding sites for CD3ε. The binding sites for EpCAM and CD3ε have been designed to bind their respective targets specifically and reversibly under the conditions found in the tumor microenvironment (TME) and to have reduced binding outside of the TME. The CAB selective binding to both the CAB EpCAM and CAB CD3ε arms are required to activate the T cell engagement against the tumor, thus enabling the combined selectivity of each CAB binding arm in the bispecific antibody. BioAtla continues to advance the ongoing Phase 1 study to evaluate the safety, pharmacokinetics, and efficacy of BA3182 in advanced adenocarcinoma patients. 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 and bispecific antibodies 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 greater than 765 active patent matters, more than 500 of which are issued patents. 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, mecbotamab vedotin, mecbotamab vedotin, a novel conditionally active AXL-targeted antibody-drug conjugate (CAB-AXL-ADC), and ozuriftamab vedotin, a novel conditionally active ROR2-targeted antibody-drug conjugate (CAB-ROR2-ADC). The Phase 2 stage CAB-CTLA-4 antibody, evalstotug, 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. The company’s first dual CAB bispecific T-cell engager antibody, BA3182, is currently in Phase 1 development. BA3182 targets EpCAM, which is highly and frequently expressed on many adenocarcinomas while engaging human CD3 expressing T cells. BioAtla has an FDA-cleared IND for its next-gen CAB-Nectin4-ADC, BA3361, the Company’s first glycoconjugate. To learn more about BioAtla, Inc. visit www.bioatla.com. Forward-looking statementsStatements 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 BioAtla’s business plans and prospects and whether its clinical trials will support registration; achievement of milestones; results, conduct, progress and timing of our research and development programs and clinical trials; expectations with respect to enrollment and dosing in its clinical trials, plans and expectations regarding future data updates, clinical trials, regulatory meetings and regulatory submissions; the potential regulatory approval path for its product candidates; expectations about the sufficiency of its cash and cash equivalents to fund operations and expectations regarding R&D expenses and cash burn. 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; 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 successful selection and prioritization of assets to focus development on selected product candidates and indications; our ability to form collaborations and partnerships with third parties and the success of such collaborations and partnerships; 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; potential adverse impacts due to any resurgence of COVID-19 and its variants; 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 March 26, 2024, in our Quarterly Report on Form 10-Q filed with the SEC on May 14, 2024, and August 8, 2024 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 BioAtla, Inc. Unaudited Condensed Statements of Operations and Comprehensive Loss(in thousands) Three Months Ended June 30, Six Months Ended June 30, 2024 2023 2024 2023 Operating expenses: Research and development expense$16,198 $30,960 $35,050 $52,657 General and administrative expense 5,774 6,241 11,379 13,474 Total operating expenses 21,972 37,201 46,429 66,131 Loss from operations (21,972) (37,201) (46,429) (66,131)Other income: Interest income 900 1,460 2,123 2,940 Other expense — (11) — (21)Total other income 900 1,449 2,123 2,919 Net loss and comprehensive loss$(21,072) $(35,752) $(44,306) $(63,212)Net loss per common share, basic and diluted (0.44) (0.75) (0.92) (1.33)Weighted-average shares of common stock outstanding, basic and diluted 48,214,893 47,706,426 48,151,176 47,639,977 BioAtla, Inc.Condensed Consolidated Balance Sheets Data(in thousands) June 30,2024 December 31,2023 (unaudited) Cash and cash equivalents $61,662 $111,471Total assets 68,638 119,658Total current liabilities 17,462 28,344Total liabilities 37,268 48,986Total stockholders’ equity 31,370 70,672Total liabilities and stockholders’ equity 68,638 119,658

Ozuriftamab vedotin (CAB-ROR2-ADC) Phase 2 data in squamous cell carcinoma of the head and neck (SCCHN) showed multiple confirmed responses and manageable safety profile; anticipate FDA meeting for SCCHN potential registrational trial in 2H 2024Evalstotug (CTLA-4 antibody) Phase 1 study progressing well, anticipate clearing dose-limiting toxicity (DLT) observation period with 1 gram (14.2 mg/kg) in 2Q 2024 and initial Phase 2 monotherapy data readout on track for 2Q 2024 and in combination with pembrolizumab in 2H 2024; anticipate FDA meeting for first-line, metastatic or unresectable, BRAF-mutated melanoma potential registrational trial in 2H 2024Mecbotamab vedotin (CAB-AXL-ADC) initial 20 patients in Phase 2 potentially registrational study in undifferentiated pleomorphic sarcoma (UPS) enrolled; anticipate FDA meeting to discuss remaining portion of the trial in 2H 2024CAB-EpCAM x CAB-CD3 (BA3182) Phase 1 dose-escalation data readout and potential initiation of Phase 2 study expected in 2H 2024CAB-Nectin4-ADC (BA3361) FDA IND clearance in MayCash balance of $80.6 million as of March 31, 2024 is expected to fund operations into 2H 2025Management to host conference call and webcast today at 4:30 PM Eastern Time SAN DIEGO, May 14, 2024 (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 financial results for the first quarter ended March 31, 2024, and provided highlights on its clinical programs. “We have had a productive start to the year, highlighted by positive clinical responses and a manageable safety profile observed with our CAB Phase 2 assets, including ozuriftamab vedotin and evalstotug. In particular, we are encouraged to see multiple responses with single agent ozuriftamab vedotin in a difficult to treat head and neck cancer population with a median of 3 prior lines of therapy and intend to schedule a meeting with the FDA later this year for a potential randomized registrational trial in this indication,” said Jay M. Short, Ph.D., Chairman, Chief Executive Officer and co-founder of BioAtla, Inc. “We also continue to be encouraged with the early clinical profile being observed with evalstotug across multiple solid tumors and will be seeking FDA guidance on a potentially registrational study in first-line, metastatic or unresectable, BRAF-mutated melanoma in the second half of this year. As we near completion of several of our Phase 2 clinical trials, we remain well-positioned to deliver on multiple important milestones throughout the remainder of the year.” Key Developments, Operational Updates and Upcoming Milestones Phase 2 Trials of ozuriftamab vedotin, CAB-ROR2-ADC in treatment-refractory SCCHN (NCT05271604) and treatment-refractory melanoma (NCT03504488) SCCHN patients (n=33) dosed at the 1.8 mg/kg 2Q3W (n=21) and Q2W (n=12) regimens; 29 evaluable patients (median 3 prior lines of treatment): To date, a total of 11 responses at the combined 2Q3W and Q2W dose regimens (5 confirmed, including 1 complete response)Among the 5 confirmed and 6 unconfirmed responders, the median number of prior treatments was 2 and 3, respectively, indicating that less heavily pretreated responders were generally more likely to receive confirmational scansDisease Control Rate (DCR) is 86%Anticipate FDA meeting in 2H 2024 for potential registrational trial in SCCHN Melanoma patients (n=29) dosed at the 1.8 mg/kg Q2W regimen (1 received 3 mg/kg Q3W in phase 1); 27 evaluable patients (median 2 prior lines of treatment). To date, a total of 5 responses (2 confirmed, including 1 complete response)DCR is 67% Ozuriftamab vedotin continues to have a manageable safety profile with no new safety signals observed Phase 1/2 dose-escalation trial of evalstotug, CAB-CTLA-4 (NCT05180799) across multiple solid tumor types responsive to CTLA-4 Phase 1 study Meaningful antitumor activity at 350 mg dose in combination with PD-1 inhibitor; new PR reported in a patient with metastatic melanomaEvolving safety data are consistent with what was previously reported with low incidence of immune mediated adverse eventsPhase 1 data to be presented at upcoming ASCO Annual Meeting in JuneAnticipate clearing DLT observation period at 1 gram (14.2 mg/kg for 70 kg person) in 2Q 2024 Initial Phase 2 monotherapy data readout in approximately 20 patients with two scans in treatment-refractory solid tumors at 350 mg or 700 mg (5 or 10 mg/kg for 70 kg person, respectively) on track for 2Q 2024Currently enrolling first-line melanoma and first-line NSCLC patients at 700 mg (10 mg/kg for 70 kg person) in combination with pembrolizumab and in combination with pembrolizumab plus chemotherapy, respectively; on track for data readout in 2H 2024Anticipate FDA meeting in 2H 2024 for potential registrational trial in first-line, metastatic or unresectable, BRAF-mutated melanoma Phase 2 Trials of mecbotamab vedotin, CAB-AXL-ADC: UPS (NCT03425279) ongoing potentially registrational trial Completed enrollment of initial 20 patients at 1.8 mg/kg 2Q3W regimen with encouraging compliance and manageable safetyAnticipate meeting with the FDA for guidance on the remaining portion of the potentially registrational trial in 2H 2024 NSCLC (NCT04681131) Dosed 33 target-agnostic patients at the 1.8 mg/kg 2Q3W regimen across squamous and non-squamous patientsStudy remains on track to evaluate initial clinical benefit in the target-agnostic, non-squamous, EGFR wild-type patient population in 2Q 2024 Phase 1/2 dose-escalation for CAB-EpCAM x CAB-CD3 TCE (BA3182, NCT05808634) On track for full dataset readout of Phase 1 study in 2H 2024Potential initiation of Phase 2 study in 2H 2024 Anti-Nectin-4-ADC (BA3361) FDA IND clearanceBA3361 is the first CAB molecule containing one of BioAtla’s novel NextGen ADC glyco-linkers with highly improved stability and tumor specific payload release. First Quarter 2024 Financial Results Research and development (R&D) expenses were $18.9 million for the quarter ended March 31, 2024 compared to $21.7 million for the same quarter in 2023. The decrease of $2.8 million was primarily due to the completion of pre-clinical development related to our Nectin-4 IND and prioritization of our clinical programs during 2023. We expect our R&D expenses to continue to decrease overall in the near-term due to recently completed enrollment in clinical trials for data sets expected to enable potentially registrational trials for our ADC programs, ozuriftamab vedotin and mecbotamab vedotin. General and administrative (G&A) expenses were $5.6 million for the quarter ended March 31, 2024 compared to $7.2 million for the same quarter in 2023. The $1.6 million decrease was primarily due to lower stock-based compensation and professional fees. Net loss for the quarter ended March 31, 2024 was $23.2 million compared to a net loss of $27.5 million for the same quarter in 2023. Net cash used in operating activities for the quarter ended March 31, 2024 was $30.8 million compared to net cash used in operating activities of $22.7 million for the same period in 2023. Cash used for the quarter ended March 31, 2024 included approximately $5.0 million in annual payments that typically only occur during our first fiscal quarter. We expect our operating cash burn to be approximately $20 million for the quarter ending June 30, 2024, and to continue to decrease in the second half of the year as we complete treatments and report findings in several of our ongoing ADC clinical trials. Cash and cash equivalents as of March 31, 2024 were $80.6 million, compared to $111.5 million as of December 31, 2023. We expect our current cash and cash equivalents will be sufficient to fund operations into the second half of 2025. First Quarter 2024 Conference Call and Webcast Details The management of BioAtla, Inc. will host a conference call and webcast for the investment community today, May 14, 2024, at 4:30 pm Eastern Time. A live webcast may be accessed here: https://viavid.webcasts.com/starthere.jsp?ei=1665384&tp_key=d63cb7a0e8. The conference call can be accessed by dialing toll-free (877) 425-9470 or (201) 389-0878 (international). The passcode for the conference call is 13745807. A replay of the webcast and slides with topline interim clinical data referenced on the call will be available through “Events & Presentations” in the Investors section of the company’s website after the conclusion of the presentation and will be archived on the BioAtla website for one year. About Mecbotamab Vedotin (BA3011) Mecbotamab vedotin, CAB-AXL-ADC, is a conditionally and reversibly active antibody drug conjugate targeting the receptor tyrosine kinase AXL. This Phase 2 stage clinical asset is targeting multiple solid tumor indications, including the treatment of soft tissue and bone sarcoma and non-small cell lung cancer (NSCLC) patients who have previously progressed on PD-1/L1, EGFR or ALK inhibitor therapies. The Office of Orphan Products Development (OOPD) at FDA granted Orphan Drug Designation to mecbotamab vedotin for the treatment of soft tissue sarcoma. About Ozuriftamab Vedotin (BA3021) Ozuriftamab vedotin, CAB-ROR2-ADC, is a conditionally and reversibly active antibody drug conjugate directed against ROR2, a receptor tyrosine kinase that is overexpressed across many different solid tumors including lung, head and neck, melanoma and breast. This Phase 2 stage clinical asset is targeting multiple solid tumor indications, including melanoma patients who have previously progressed on PD-1/L1 therapy and SCCHN patients who have previously progressed on PD-1/L1 therapies with or without platinum chemotherapy. About Evalstotug (BA3071) Evalstotug, is a CAB anti-CTLA-4 antibody that is being developed as an immuno-oncology agent with the goal of delivering efficacy at least comparable to the approved anti-CTLA-4 antibodies, but with lower toxicities due to the CAB's tumor microenvironment-restricted activity. This may enable safer anti-CTLA-4 antibody combination therapies, such as with anti-PD-1 antibody checkpoint inhibitors, and potentially broaden the patient population tolerant to combination therapy and deliver greater efficacy. Like our other CAB candidates, this Phase 2 clinical asset is designed to be conditionally and reversibly active in the tumor microenvironment. Evalstotug is being developed as a potential therapeutic for multiple solid tumor indications that are known to be responsive to CTLA-4 treatment in combination with a PD-1 blocking agent. About BA3182 BioAtla is developing BA3182 as a potential anticancer therapy for patients with advanced adenocarcinoma. BA3182 is a (CAB) EpCAM x (CAB) CD3 bispecific T cell engager antibody that contains two binding sites for EpCAM and two binding sites for CD3ε. The binding sites for EpCAM and CD3ε have been designed to bind their respective targets specifically and reversibly under the conditions found in the tumor microenvironment (TME) and to have reduced binding outside of the TME. The CAB selective binding to both the CAB EpCAM and CAB CD3ε arms are required to activate the T cell engagement against the tumor, thus enabling the combined selectivity of each CAB binding arm in the bispecific antibody. BioAtla continues to advance the ongoing Phase 1 study to evaluate the safety, pharmacokinetics, and efficacy of BA3182 in advanced adenocarcinoma patients. About BA3361 BA3361, CAB-Nectin4-ADC, is a conditionally and reversibly active antibody drug conjugate directed against Nectin4, a cell-cell adhesion molecule overexpressed in multiple human malignancies. The Nectin4-binding domains of BA3361 have been optimized for binding under tumor microenvironment (TME) conditions and reduced binding under normal physiological conditions. BA3361 is the first molecule containing one of BioAtla’s novel NextGen ADC glyco-linkers with highly improved stability and tumor specific payload release. BA3361 demonstrated complete tumor regression observed in several cell line derived xenograft models, superior efficacy to an enfortumab vedotin analogue in a patient-derived xenograft pancreatic cancer model, and reduced toxicity through CAB selectivity. 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 and bispecific antibodies 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 greater than 765 active patent matters, more than 485 of which are issued patents. 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, mecbotamab vedotin, mecbotamab vedotin, a novel conditionally active AXL-targeted antibody-drug conjugate (CAB-AXL-ADC), and ozuriftamab vedotin, a novel conditionally active ROR2-targeted antibody-drug conjugate (CAB-ROR2-ADC). The Phase 2 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. The company’s first dual CAB bispecific T-cell engager antibody, BA3182, is currently in Phase 1 development. BA3182 targets EpCAM, which is highly and frequently expressed on many adenocarcinomas while engaging human CD3 expressing T cells. BioAtla has an FDA-cleared IND for its next-gen CAB-Nectin4-ADC, BA3361, the Company’s first glycoconjugate. 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 and whether our clinical trials will support registration; plans to form collaborations and other strategic partnerships for selected assets; achievement of milestones; 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 and expectations 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 to fund operations; and expectations regarding R&D expenses and cash burn. 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; 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 successful selection and prioritization of assets to focus development on selected product candidates and indications; our ability to form collaborations and partnerships with third parties and the success of such collaborations and partnerships; 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; potential adverse impacts due to any resurgence of COVID-19 and its variants; 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 March 26, 2024 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.com858.356.8945 External Contact: Bruce MackleLifeSci Advisors, LLCbmackle@lifesciadvisors.com BioAtla, Inc.Unaudited Condensed Statements of Operations and Comprehensive Loss(in thousands, except share data) Three Months EndedMarch 31, 2024 2023Operating expenses: Research and development expense $18,852 $21,697 General and administrative expense 5,605 7,233 Total operating expenses 24,457 28,930 Loss from operations (24,457) (28,930)Other income: Interest income 1,223 1,480 Other expense — (10)Total other income 1,223 1,470 Net loss and comprehensive loss $(23,234) $(27,460)Net loss per common share, basic and diluted $(0.48) $(0.58)Weighted-average shares of common stock outstanding, basic and diluted 48,087,460 47,578,418 BioAtla, Inc.Condensed Consolidated Balance Sheets Data(in thousands) March 31,2024 December 31,2023 (unaudited) Cash and cash equivalents $80,630 $111,471 Total assets 89,197 119,658 Total current liabilities 19,260 28,344 Total liabilities 39,481 48,986 Total stockholders’ equity 49,716 70,672 Total liabilities and stockholders’ equity 89,197 119,658

Observed additional clinical responses and FDA feedback supports path forward for CAB-AXL-ADC (BA3011) non-small cell lung cancer (NSCLC) registrational study; detailed interim Phase 2 data to be presented at upcoming IASLC conference in early December and discussed at KOL event on December 4, 2023Observed new PRs with CAB-ROR2-ADC (BA3021) Q2W dosing regimen in the Phase 2 melanoma study and a new PR with BA3021 2Q3W in the Phase 2 head and neck studyInitiated Phase 2 CAB-CTLA-4 (BA3071) study; First Patient In (FPI) completed; Phase 1 data to be presented at upcoming R&D Day on December 13, 2023Phase 1 study for CAB-EpCAM x CAB-CD3 bispecific T-cell engager (TCE), BA3182, ongoing; data readout remains on track in 2024Cash balance of $141.3 million now expected to fund operations into 2H 2025 Management to host conference call and webcast today at 4:30 PM Eastern Time SAN DIEGO, Nov. 07, 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 financial results for the third quarter ended September 30, 2023, and provided an update on its clinical programs. “At BioAtla, our highest priority is to deliver innovative, life-changing therapies to cancer patients with significant unmet medical needs. We have consistently observed multiple clinical responses in treatment-refractory NSCLC populations with CAB-AXL-ADC, BA3011. In addition, we recently have observed new PRs with CAB-ROR2-ADC, BA3021 in melanoma and head and neck cancer as we continue to dose patients, further underscoring our promising CAB-ADC opportunities,” said Jay M. Short, Ph.D., Chairman, Chief Executive Officer and co-founder of BioAtla, Inc. “We are also advancing our CAB-CTLA-4, BA3071, and now have initiated the Phase 2 study and will provide an update at our upcoming R&D day in December. As we have obtained data to support several value inflection points across our CAB portfolio, we believe that forming one or more strategic collaborations with major pharmaceutical partners can accelerate development of selected assets and maximize their market opportunities.” CAB-ADC Clinical-Stage Programs Phase 2 Trial of Mecbotamab Vedotin, BA3011: NSCLC In treatment-refractory patients (median 3 prior lines of therapy) receiving BA3011 Q2W monotherapy who previously experienced PD-1 treatment failure and were evaluable for efficacy at 12 weeks, the observed objective response rate was 27.8%In treatment-refractory patients with epidermal growth factor receptor (EGFR) wild-type, non-squamous NSCLC who previously experienced PD-1 treatment failure, 33.3% had a partial response (PR) to BA3011 monotherapyContinue to observe clinical benefit in patients, including multiple PRs at a TmPS score of 1% and exploring the potential clinical benefits in AXL TmPS negative patientsBased upon our meeting with the FDA in October, we believe the FDA is supportive of our registrational path forward; details forthcoming at IASLC conference and KOL event in early December Undifferentiated Pleomorphic Sarcoma (UPS) Phase 2 potentially registrational study ongoing Bone and soft tissue sarcomas All cohorts completed with additional subtypes achieving the predefined efficacy and safety criteriaPlanned submission of data to medical meeting in 2024 Phase 2 Trials of Ozuriftamab Vedotin, BA3021: All dosing to be completed before year-end 2023Melanoma Completed enrollment Q2W targeted cohort who previously progressed on PD-1/L1 therapyTo date, eight melanoma monotherapy patients are evaluable with reported first scan data across Phase 1 and Phase 2. Among these, we observed four responses, two stable disease and two progressive disease with at least one response observed in a ROR2 TmPS negative patient. The remainder of patients in the targeted cohort will have had the opportunity to have first scan by year end.Continue to collect data in ongoing study Squamous Cell Carcinoma of Head and Neck (SCCHN) On track to complete all dosing regimens enrollment by year-end 2023; new PR observed in the first Phase 2 patient scanned at 2Q3W (ROR2 TmPS negative)Continue to collect data in ongoing study NSCLC Clinical benefit observed and tumor volume reduction in Q2W dosing regimen but did not meet our internal criteria for advancing at this dose; currently no plans to internally explore additional dosing regimens Phase 2 Investigator-initiated Trial of platinum-resistant ovarian cancer Interim analysis of n=10 patients in each BA3011 and BA3021 Q2W cohorts demonstrated modest disease control, but did not meet our internal criteria for advancing at this dose; currently no plans to internally explore additional dosing regimensData disclosure planned for future medical meeting at investigator’s discretion CAB-CTLA-4 I/O Clinical-Stage Program Phase 1/2 dose-escalation trial of CAB-CTLA-4, BA3071 basket trial: Phase 1 data readout and path forward at upcoming R&D Day on December 13Initiated Phase 2; FPI completed CAB-T-Cell Engager Clinical-Stage Program Phase 1/2 dose-escalation for CAB-EpCAM x CAB-CD3 TCE, BA3182: Progressing Phase 1 study for the treatment of advanced adenocarcinomaAnticipated completion of Phase 1 and data readout remains on track in 2024 Presentations Upcoming poster presentation at the IASLC North America Conference on Lung Cancer (NACLC), titled “Phase 2 Trial of Mecbotamab Vedotin (BA3011), a CAB-AXL-ADC, Alone or in Combination With Nivolumab in Patients With Non-Squamous NSCLC”, in early DecemberKOL event planned for December 4 following conclusion of the IASCL conference, to discuss detailed interim Phase 2 data on CAB-AXL-ADC, BA3011, in NSCLCR&D Day planned for December 13 to discuss CAB-CTLA-4 (BA3071) Phase 1/2 basket trial Third Quarter 2023 Financial Results Cash and cash equivalents as of September 30, 2023 were $141.3 million, compared to $215.5 million as of December 31, 2022. We expect current cash and cash equivalents will be sufficient to fund planned operations including prioritized CAB programs into second half of 2025. Research and development (R&D) expenses were $28.4 million for the quarter ended September 30, 2023 compared to $19.8 million for the same quarter in 2022. The increase of $8.6 million was primarily driven by a $6.3 million increase in our clinical product development expenses primarily related to the launch of our AXL UPS potentially registrational trial, and a $1.8 million increase in preclinical product development expenses primarily related to our CAB B7H3 x CD3 bispecific T-cell engager. We expect our R&D expenses to remain variable from quarter to quarter as we continue to advance our clinical programs, then decreasing after we complete enrollment and focus development on selected high potential indications. General and administrative (G&A) expenses were $6.6 million for the quarter ended September 30, 2023 compared to $6.3 million for the same quarter in 2022. The $0.3 million change was attributable to an increase in professional services and consulting expenses for the 2023 period. We expect our G&A expenses to remain flat to moderately increasing to support development of our prioritized CAB programs. Net loss for the third quarter ended September 30, 2023 was $33.3 million compared to a net loss of $25.8 million for the same quarter in 2022. Net cash used in operating activities for the nine months ended September 30, 2023 was $74.1 million compared to net cash used in operating activities of $66.1 million for the same period in 2022. The increase in net cash used in operating activities for the first nine months of 2023 is primarily due to an increase in research and development expenses related to our program development efforts as compared to the first nine months of 2022. Third Quarter 2023 Conference Call and Webcast Details The management of BioAtla, Inc. will host a conference call and webcast for the investment community today, November 7, 2023, at 4:30 pm Eastern Time. A live webcast may be accessed here: https://viavid.webcasts.com/starthere.jsp?ei=1635568&tp_key=63f5901bb0. The conference call can be accessed by dialing toll-free (888) 886-7786 or (416) 764-8658 (international). The passcode for the conference call is 05202391. A replay of the webcast and slides with topline interim clinical data referenced on the call will be available through “Events & Presentations” in the Investors section of the company’s website after the conclusion of the presentation and will be archived on the BioAtla website for one year. About Mecbotamab Vedotin (BA3011) Mecbotamab vedotin, CAB-AXL-ADC, is a conditionally and reversibly active antibody drug conjugate targeting the receptor tyrosine kinase AXL. This Phase 2 stage clinical asset is targeting multiple solid tumor types, including soft tissue and bone sarcoma and non-small cell lung cancer (NSCLC) that have previously progressed on PD-1/L1, EGFR or ALK inhibitor therapies. The Office of Orphan Drug Products (OODP) at FDA granted Orphan Drug Designation to mecbotamab vedotin for the treatment of soft tissue sarcoma. About Ozuriftamab Vedotin (BA3021) Ozuriftamab vedotin, CAB-ROR2-ADC, is a conditionally and reversibly active antibody drug conjugate directed against ROR2, a receptor tyrosine kinase that is overexpressed across many different solid tumors including breast, lung, head and neck and melanoma. This Phase 2 stage clinical asset is targeting multiple solid tumor types, including NSCLC that have previously progressed on PD-1/L1, EGFR or ALK inhibitor therapies, melanoma that have previously progressed on PD-1/L1 therapy and SCCHN that have previously progressed on PD-1/L1 therapies with or without platinum chemotherapy. About BA3071 BA3071, is a CAB anti-CTLA-4 antibody that is being developed as an immuno-oncology agent with the goal of delivering efficacy at least comparable to the approved anti-CTLA-4 antibodies, but with lower toxicities due to the CAB's tumor microenvironment-restricted activity. This may enable safer anti-CTLA-4 antibody combination therapies, such as with anti-PD-1 antibody checkpoint inhibitors, and potentially broaden the patient population tolerant to combination therapy and deliver greater efficacy. Like our other CAB candidates, this Phase 2 clinical asset is designed to be conditionally and reversibly active in the tumor microenvironment. BA3071 is being developed as a potential therapeutic for multiple solid tumor indications that are known to be responsive to CTLA-4 treatment in combination with a PD-1 blocking agent. About BA3182 BioAtla is developing BA3182 as a potential anticancer therapy for patients with advanced adenocarcinoma. BA3182 is a conditionally active biologic (CAB) EpCAM/CD3 bispecific T cell engager antibody that contains two binding sites for EpCAM and two binding sites for CD3ε. The binding sites for EpCAM and CD3ε have been designed to bind their respective targets specifically and reversibly under the conditions found in the TME and to have reduced binding outside of the TME. The CAB selective binding to both the CAB EpCAM and CAB CD3ε arms are required to activate the T cell engagement against the tumor, thus enabling the combined selectivity of each CAB binding arm in the bispecific antibody. BioAtla continues to advance the ongoing Phase 1 study to evaluate the safety, pharmacokinetics, and efficacy of BA3182 in advanced adenocarcinoma patients. About EpCAM EpCAM is involved in the maintenance of epithelial integrity, and its expression is associated with proliferation during morphogenesis, tissue regeneration, and stem cell maintenance. Expression levels of EpCAM vary amongst different organs and cell types, with epithelia of colon, small intestine, lung, pancreas, liver and gall bladder expressing the highest levels of EpCAM protein. Given the functions and properties of EpCAM protein, high levels of EpCAM expression have been found in many carcinomas. EpCAM is highly and frequently expressed in the vast majority of carcinomas and their metastases and has been considered as a potential prognostic and therapeutic marker for many carcinomas. 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 and bispecific antibodies 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 greater than 700 patents filed, more than 400 of which have been issued. 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, 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 2 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. The company’s first bispecific T-cell engager antibody, BA3182, is currently in Phase 1 development. BA3182 targets EpCAM, which is highly and frequently expressed on many adenocarcinomas while engaging human CD3 expressing T cells. 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 and whether our clinical trials will support registration; achievement of milestones; 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 and expectations regarding future data updates, clinical trials, regulatory meetings and regulatory submissions; plans to form collaborations or other strategic partnerships for selected assets; the potential regulatory approval path for our product candidates; expectations about the sufficiency of our cash and cash equivalents to fund planned operations, which includes plans to not explore additional dosing regimens, delaying certain pre-clinical development programs and to prioritize and focus development on selected assets and indications; 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; 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 successful selection and prioritization of assets to focus development on selected product candidates and indications; our ability to form collaborations and partnerships with third parties and the success of such collaborations and partnerships; 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; potential adverse impacts due to any resurgence of COVID-19 and its variants 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 March 23, 2023, in our Quarterly Report on Form 10-Q filed with the SEC on May 11, 2023, August 1, 2023 and November 7, 2023 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 BioAtla, Inc. Unaudited Condensed Statements of Operations and Comprehensive Loss(in thousands) Three Months Ended September 30, Nine Months Ended September 30, 2023 2022 2023 2022 Operating expenses: Research and development expense$28,400 $19,839 $81,057 $57,473 General and administrative expense 6,620 6,340 20,094 22,107 Total operating expenses 35,020 26,179 101,151 79,580 Loss from operations (35,020) (26,179) (101,151) (79,580)Other income (expense): Interest income 1,734 370 4,674 601 Other income (expense) (39) 30 (60) 40 Total other income (expense) 1,695 400 4,614 641 Net loss and comprehensive loss$(33,325)$(25,779) $(96,537)$(78,939) BioAtla, Inc.Condensed Consolidated Balance Sheets Data(in thousands) September 30,2023 December 31,2022 Cash and cash equivalents $141,282 $215,507Total assets 151,362 225,736Total current liabilities 35,602 23,131Total liabilities 56,659 45,397Total stockholders’ equity 94,703 180,339Total liabilities and stockholders’ equity 151,362 225,736