ZNTL

Following U.S. regulatory discussions, accelerated approval strategy remains intact, supported by DENALI Part 2 Enrollment completed in Part 2a and 2b of the DENALI trial; Part 2c is enrolling DENALI Part 2 topline readout expected in 1H 2027 to allow for data maturation post full enrollment $174.6 million in cash, cash equivalents and marketable securities as of June 30, 2026, providing runway into late 2027 to support execution of key milestones SAN DIEGO, Aug. 06, 2026 (GLOBE NEWSWIRE) -- Zentalis® Pharmaceuticals, Inc. (Nasdaq: ZNTL), a clinical oncology innovator advancing late-stage development of an investigational, potentially first-in-class WEE1 inhibitor, azenosertib, as a biomarker-driven treatment approach for ovarian cancer, today announced financial results for the second quarter ended June 30, 2026, and highlighted recent corporate, regulatory and clinical progress and upcoming expected milestones. "We have achieved important milestones on the continued advancement of azenosertib in our registration-intended DENALI Phase 2 and ASPENOVA Phase 3 trials for patients with Cyclin E1-positive platinum-resistant ovarian cancer (PROC), including completing the enrollment of DENALI Part 2b and aligning with the U.S. Food and Drug Administration (FDA) following a Type D meeting on our selected dose and DENALI study population to support potential accelerated approval,” said Julie Eastland, Chief Executive Officer of Zentalis. "We remain as confident as ever that azenosertib has the potential to be an important oral, non-chemotherapy treatment option for the approximately 50% of PROC patients with Cyclin E1-positive tumors, who have limited options. We expect to provide the topline readout of DENALI Part 2 in 1H 2027. We continue to advance the confirmatory ASPENOVA Phase 3 trial with the goal of bringing a potential first-in-class WEE1 therapy to market for this underserved patient population globally. In addition to the lead indication, we see opportunity for expansion of azenosertib into platinum-sensitive settings of ovarian cancer and additional tumor types through combinations." "We are well capitalized as of June 30, 2026 with cash, cash equivalents and marketable securities of $174.6 million to support the execution of key milestones and to continue advancing our regulatory strategy for both accelerated and full approval in PROC,” Ms. Eastland continued. Business Updates Regulatory Update: Met with the FDA in a Type D meeting regarding the Company’s accelerated approval strategy, including dose. The FDA had no objection to the continued study of the selected monotherapy dose of azenosertib at the 400mg once daily on a 5-days-on, 2-days-off schedule (400mg QD 5:2) in patients with Cyclin E1-positive PROC, selected based on a pre-specified interim analysis from DENALI Part 2a. The FDA acknowledged the DENALI Part 2 study population, including the 2c cohort, has the potential to support an accelerated approval pathway, subject to the strength of the data and the landscape of approved agents at the time of regulatory action. DENALI Part 2 Enrollment and Integrated Topline Readout: Enrollment in DENALI Parts 2a and 2b is complete. Earlier this year, the Company expanded DENALI Part 2 to broaden the overall study population and enrich patients previously treated with a taxane-containing regimen for PROC, aligning the study population with the evolving treatment landscape of approved agents. DENALI Part 2c is currently enrolling. The integrated dataset of DENALI Parts 2a, 2b, and 2c is designed to support accelerated approval in the Cyclin E1 biomarker-selected patient population, subject to regulatory review. The Company expects to provide a topline readout in 1H 2027 to allow for data maturation post full enrollment. ASPENOVA Phase 3 First Patient Dosed: In May 2026, announced the first patient was dosed in the Phase 3 ASPENOVA confirmatory trial designed to satisfy FDA requirements for U.S. full approval and to support approval in major ex-U.S. markets. The trial is currently enrolling. ESMO 2026 Abstract Acceptances: Announced that the European Society for Medical Oncology (ESMO) has accepted an abstract for rapid oral presentation at the 2026 ESMO Annual Meeting featuring overall survival analysis from Part 1b of the DENALI study of azenosertib in PROC patients. A second abstract featuring the ASPENOVA Phase 3 trial design has been accepted for a trial-in-progress poster presentation. MUIR Clinical Trial Data Presented at ASCO 2026: Presented results from Part 1 of the Phase 1b MUIR trial at the 2026 American Society of Clinical Oncology (ASCO) Annual Meeting, focusing on an evaluation of azenosertib in combination with paclitaxel in PROC. The data showed combinability and activity of azenosertib in an all-comer PROC setting, demonstrating the potential for azenosertib in multiple lines of ovarian cancer and more broadly in combination with cytotoxic agents in other tumor types. Part 2 enrollment is ongoing for azenosertib in combination with bevacizumab for 2L platinum sensitive ovarian cancer. Expanded Commercial Capabilities: In May 2026, announced the appointments of Shannon Campbell to the Company’s Board of Directors and Sarah Kelly as SVP of Commercial Strategy to support commercialization readiness. Second Quarter 2026 Financial Results Cash Position: Cash, cash equivalents and marketable securities were $174.6 million as of June 30, 2026, compared to $245.9 million as of December 31, 2025. The Company believes that its existing cash, cash equivalents and marketable securities as of June 30, 2026 will be sufficient to fund its operating expenses and capital expenditure requirements into late 2027. Research and Development Expenses: Research and development expenses for the three months ended June 30, 2026 were $35.2 million, compared to $27.6 million for the three months ended June 30, 2025. The increase of $7.6 million was primarily due to a $7.0 million milestone payment to Recurium IP Holdings, LLC required as a result of the commencement of the Phase 3 ASPENOVA clinical trial and an increase of $5.2 million related to clinical expenses and drug manufacturing, including costs associated with advancing the DENALI and ASPENOVA trials. This increase was partially offset by a decrease of $4.5 million for personnel expense, of which $2.1 million was non-cash stock-based compensation, and a decrease of $0.1 million related to allocated overhead. General and Administrative Expenses: General and administrative expenses for the three months ended June 30, 2026 were $9.2 million, compared to $8.4 million during the three months ended June 30, 2025. This increase of $0.8 million was primarily attributable to an increase of $1.7 million for consulting and outside services. This increase was partially offset by a decrease of $0.9 million for non-cash stock-based compensation. Total Operating Expenses: Total operating expenses were $44.4 million for the three months ended June 30, 2026, compared to $36.1 million for the three months ended June 30, 2025. About Azenosertib Azenosertib is an investigational, potentially first-in-class, selective, and orally bioavailable inhibitor of WEE1 currently being evaluated in clinical studies in ovarian cancer and additional tumor types. WEE1 acts as a master regulator of the G1-S and G2-M cell cycle checkpoints, through negative regulation of both CDK1 and CDK2, to prevent replication of cells with damaged DNA. By inhibiting WEE1, azenosertib enables cell cycle progression, despite high levels of DNA damage, thereby resulting in the accumulation of DNA damage and leading to mitotic catastrophe and cancer cell death. Azenosertib is in late-stage development as a potential treatment for Cyclin E1-positive PROC. There is currently no approved treatment option specifically for this biomarker-selected population which comprises approximately 50% of PROC patients. Cyclin E1 protein overexpression has been established as a sensitive and specific predictive biomarker for identifying patients who could potentially derive benefit from azenosertib treatment. About DENALI Clinical Trial DENALI is a multi-part Phase 2 registration-intended clinical trial (NCT05128825) studying azenosertib in PROC patients. Part 1b enrolled patients with PROC regardless of Cyclin E1 protein expression, all treated at 400mg QD 5:2. Part 2 is prospectively enrolling PROC patients with Cyclin E1 protein overexpression based on Zentalis' proprietary immunohistochemistry cutoff. Part 2, in total, is designed to support accelerated approval, pending positive study outcomes and further discussions with the FDA. The study design consists of the following parts: Part 2a: Dose confirmation evaluated two doses, 300mg QD 5:2 and 400mg QD 5:2, with approximately 30 patients enrolled per dose group. 400mg QD 5:2 was selected as the optimal monotherapy dose. Recruitment at the 300mg QD 5:2 dose level has been discontinued. All patients enrolled in Part 2a will contribute to the overall safety database submitted to the FDA. Part 2b: Enrollment expansion at the selected 400mg QD 5:2 dose up to approximately 100 patients, including patients at this dose in Part 2a. This cohort has completed enrollment. Part 2c: Broadening study population, which is expected to include approximately 40 patients previously treated with a taxane-containing regimen for PROC. This cohort is currently enrolling. Zentalis expects to complete enrollment in all cohorts of DENALI Part 2 (2a, 2b, 2c) and provide a topline readout by 1H 2027. For physician and patient information about the DENALI trial, please visit www.denalitrial.com. About ASPENOVA Clinical TrialASPENOVA is a Phase 3 randomized, confirmatory clinical trial designed to support full approval of azenosertib in patients with Cyclin E1-positive PROC. The trial is expected to enroll approximately 420 patients and compare azenosertib monotherapy at 400mg QD 5:2 to investigator's choice of standard-of-care single-agent chemotherapy (paclitaxel, pegylated liposomal doxorubicin [PLD], gemcitabine, or topotecan) in this biomarker-selected population. The primary endpoint is progression-free survival (PFS); key secondary endpoints include overall survival (OS) and overall response rate (ORR). The trial design was based on feedback from the U.S. FDA regarding requirements for seeking approval under the accelerated approval pathway and requirements to support potential conversion to full approval. About MUIR Clinical TrialMUIR (NCT04516447) is a multi-part, open-label Phase 1b clinical trial evaluating the safety, efficacy, and preliminary clinical activity of azenosertib combinations in patients with ovarian cancer. Part 1 enrolled patients with platinum-resistant ovarian cancer (PROC) treated with azenosertib in combination with one of four chemotherapy regimens: carboplatin, gemcitabine, pegylated liposomal doxorubicin, or paclitaxel. Primary objectives are safety and tolerability, with key secondary objectives including clinical activity assessed by objective response rate, duration of response, and progression-free survival per RECIST v1.1. Part 2 is evaluating azenosertib plus bevacizumab as maintenance regimen (first [1L] or second line [2L]) in patients with advanced ovarian, peritoneal, or fallopian tube cancer following platinum-based chemotherapy. The dose expansion portion will evaluate azenosertib at the recommended dose in combination with bevacizumab in patients with platinum-sensitive ovarian cancer in 2L who progressed while on a PARP inhibitor for 1L maintenance. The primary objective is safety and tolerability; secondary objectives include preliminary clinical activity of the combination as assessed by progression-free survival for the dose expansion portion. The dose expansion portion is currently open for enrollment. About Zentalis PharmaceuticalsZentalis is a clinical oncology innovator developing a treatment approach for ovarian cancer and multiple tumor types. Leveraging therapeutics development and biomarker expertise, Zentalis is advancing monotherapy and combination studies of its investigational first-in-class WEE1 inhibitor, azenosertib. Focused on translating WEE1 science into clinical practice, we aim to equip physicians with a targeted, non-chemo, orally available medicine that enhances treatment experience, choice, and outcomes. Our mission: to unburden cancer patients with more convenience and care.​ For more information, please visit www.zentalis.com. Follow Zentalis on LinkedIn at www.linkedin.com/company/zentalis-pharmaceuticals. Forward-Looking StatementsThis press release contains forward-looking statements within the meaning of the U.S. Private Securities Litigation Reform Act of 1995, as amended. All statements contained in this press release that do not relate to matters of historical fact should be considered forward-looking statements, including, but not limited to, statements regarding the potential for azenosertib to be first-in-class; the continued development of azenosertib; the clinical and therapeutic potential of azenosertib, including the potential for azenosertib to be an important treatment option for patients with ovarian cancer or other indications; the Company’s biomarker-driven strategy for azenosertib; the potential to advance research on additional areas of opportunity for azenosertib as maintenance therapy in ovarian cancer and to explore additional tumor types; the Company’s anticipated milestones and the timing thereof, including the anticipated enrollment completion of DENALI Part 2, the topline readout from DENALI Part 2, and the design, conduct and timing of our confirmatory ASPENOVA Phase 3 and MUIR Phase 1b trials; the Company's commercialization planning and readiness activities; the potential for expansion of azenosertib into platinum-sensitive settings and additional tumor types; the Company’s anticipated cash runway; and the Company’s planned regulatory strategy for azenosertib and the timing thereof, including the potential for DENALI Part 2 to support an accelerated approval and for ASPENOVA to support conversion to a full approval and ex-US approval. The terms “anticipate,” “advance,” “believe,” “continue,” “design,” “develop,” “expect,” “focus,” “intend,” “plan,” “potential,” “runway,” “strategy,” “target,” and “will” and similar references are intended to identify forward-looking statements, although not all forward-looking statements contain these identifying words. These statements are neither promises nor guarantees, but involve known and unknown risks, uncertainties and other important factors that may cause our actual results, performance or achievements to be materially different from any future results, performance or achievements expressed or implied by the forward-looking statements, including, but not limited to, the following: our limited operating history, which may make it difficult to evaluate our current business and predict our future success and viability; we have and expect to continue to incur significant losses; our need for additional funding, which may not be available; our substantial dependence on the success of azenosertib; our plans, including the costs thereof, of development of a companion diagnostic; risks relating to the regulatory approval process or ongoing regulatory obligations; the outcome of preclinical testing and early trials may not be predictive of the success of later clinical trials; potential unforeseen events during clinical trials could cause delays or other adverse consequences; our product candidates may cause serious adverse side effects; the interim, initial, “topline,” and preliminary data from our clinical trials may change as more patient data becomes available, and are subject to audit and verification procedures that could result in material changes in the final data; our reliance on third parties; effects of significant competition; the possibility of system failures or security breaches; risks relating to intellectual property; our ability to attract, retain and motivate qualified personnel, and risks relating to management transitions; significant costs as a result of operating as a public company; and the other important factors discussed under the caption “Risk Factors” in our most recently filed periodic report on Form 10-K or 10-Q and subsequent filings with the U.S. Securities and Exchange Commission (SEC) and our other filings with the SEC. Any such forward-looking statements represent management’s estimates as of the date of this press release. While we may elect to update such forward-looking statements at some point in the future, we disclaim any obligation to do so, even if subsequent events cause our views to change. ZENTALIS® and its associated logo are trademarks of Zentalis and/or its affiliates. All website addresses and other links in this press release are for information only and are not intended to be an active link or to incorporate any website or other information into this press release. Contact:Aron FeingoldVP, Investor Relations & Corporate [email protected]

400mg QD 5:2 selected as azenosertib monotherapy pivotal study dose based on favorable benefit-risk profile in DENALI Part 2a, supporting advancement in registration-intended trials DENALI Phase 2 trial topline readout expected by year-end 2026, with potential to support accelerated approval pathway, pending data outcomes and FDA feedback ASPENOVA Phase 3 confirmatory trial in Cyclin E1-positive PROC initiated with first patient dosed; designed to support conversion to PROC full approval and ex-US registrations $211.8 million in cash, cash equivalents and marketable securities as of March 31, 2026, providing runway into late 2027 with funding to support execution of key milestones SAN DIEGO, May 12, 2026 (GLOBE NEWSWIRE) -- Zentalis® Pharmaceuticals, Inc. (Nasdaq: ZNTL), a clinical oncology innovator advancing late-stage development of investigational first-in-class WEE1 inhibitor azenosertib as a biomarker-driven treatment approach for ovarian cancer, today announced financial results for the first quarter ended March 31, 2026, and highlighted recent clinical progress. "This quarter, we built momentum with achievement of key milestones advancing azenosertib in our registration-intended Phase 2 and Phase 3 trials for patients with Cyclin E1-positive platinum-resistant ovarian cancer (PROC),” said Julie Eastland, Chief Executive Officer of Zentalis. "Our core focus is on bringing a convenient, oral, non-chemotherapy treatment option to approximately 50% of PROC patients who are Cyclin E1-positive and may experience poorer prognosis and limited benefit from standard-of-care therapies. Pivotal dose selection supports our regulatory strategy, positioning us to pursue accelerated approval through the DENALI Part 2 trial while simultaneously advancing ASPENOVA as our confirmatory trial—together charting a pathway to bring a potential first-in-class therapy to market for this underserved patient population. Following dose selection, we initiated pre-commercial launch preparedness activities to add commercial capabilities to the organization, scale manufacturing capacity and advance Cyclin E1 companion diagnostic market development. Beyond the lead indication, we see substantial opportunity for strategic expansion of azenosertib into platinum-sensitive or first-line maintenance settings of ovarian cancer, additional tumor types, and combination approaches." "With a cash position of $211.8 million as of March 31, 2026, we have runway into late 2027 and the resources to support execution of key milestones, most importantly the DENALI Part 2 topline readout, and ongoing trials,” Ms. Eastland continued. Clinical Development Progress Pivotal Dose Selected for Registration-Intended Azenosertib Monotherapy Program in Cyclin E1-Positive PROC: In April 2026, selected 400mg once daily on a 5-days-on, 2-days-off schedule (400mg QD 5:2) as the pivotal study dose for azenosertib monotherapy in patients with Cyclin E1-positive PROC based on a pre-specified interim analysis from DENALI Part 2a that showed a meaningful, clearly differentiated response rate at 400mg QD 5:2 and comparable safety profiles across both dose groups. The analysis revealed observed improvements in several key measures, including a discontinuation rate due to adverse events at approximately half the rate reported in DENALI Part 1b and no treatment-related deaths. Concurrently, the Company expanded DENALI Part 2 to include Part 2c, a new cohort broadening inclusion to approximately 40 patients previously treated with a taxane-containing regimen for PROC, to maintain alignment between the study population and the evolving treatment landscape. DENALI Parts 2b and 2c are currently enrolling. DENALI Part 2 is designed to support a potential accelerated approval pathway in the Cyclin E1 biomarker-selected patient population, subject to regulatory review. The Company expects to complete enrollment in all cohorts of DENALI Part 2 and provide a topline readout by year-end 2026. ASPENOVA Phase 3 First Patient Dosed: In May 2026, announced the first patient was dosed in the Phase 3 ASPENOVA confirmatory trial designed to satisfy FDA requirements for potential conversion to full approval and to support approval in major ex-US markets. ASPENOVA is a randomized, controlled Phase 3 trial that is expected to enroll approximately 420 patients and compare azenosertib monotherapy at 400mg QD 5:2 to investigator's choice of standard-of-care single-agent chemotherapy (paclitaxel, pegylated liposomal doxorubicin, gemcitabine, or topotecan) in patients with Cyclin E1-positive PROC. The trial is currently enrolling. MUIR Part 2 dose expansion evaluating azenosertib in combination with bevacizumab as maintenance therapy in ovarian cancer. MUIR is a multi-part, open-label Phase 1b clinical trial evaluating the safety, efficacy and preliminary clinical activity of azenosertib as a combination therapy in patients with ovarian cancer. The dose expansion cohort of Part 2 is currently open for enrollment of azenosertib in combination with bevacizumab in second-line platinum-sensitive ovarian cancer (PSOC) patients for maintenance treatment, whose disease progressed while on a PARP inhibitor. Medical Meeting Presentations Supporting Pipeline Strategy AACR 2026: Presented two posters at the American Association for Cancer Research (AACR) Annual Meeting featuring: (1) compelling preclinical data showing azenosertib combinations can induce complete tumor responses in a model resistant to emerging antibody-drug conjugate (ADC) therapies in triple-negative breast cancer (TNBC), supporting the potential for pipeline expansion beyond ovarian cancer; and (2) real-world data from two independent cohorts demonstrating that Cyclin E1-positive ovarian cancer patients experience significantly worse clinical outcomes, independent of CCNE1 gene amplification status, reinforcing the potential for azenosertib to address the unmet need for these patients. ASCO 2026 Abstract Acceptance: Announced that the American Society of Clinical Oncology (ASCO) has accepted an abstract for presentation at the 2026 ASCO Annual Meeting featuring results from Part 1 of the Phase 1b MUIR trial, focusing on an evaluation of azenosertib in combination with paclitaxel in platinum-resistant ovarian cancer (PROC). The data will showcase combinability and activity in an all-comer setting, demonstrating the broad potential for azenosertib in multiple lines of ovarian cancer and other tumor types. First Quarter 2026 Financial Results Cash Position: Cash, cash equivalents and marketable securities were $211.8 million as of March 31, 2026, compared to $245.9 million as of December 31, 2025. The Company believes that its existing cash, cash equivalents and marketable securities as of March 31, 2026 will be sufficient to fund its operating expenses and capital expenditure requirements into late 2027. Research and Development Expenses: Research and development (R&D) expenses for the three months ended March 31, 2026 were $28.7 million, compared to $27.2 million for the three months ended March 31, 2025. The increase of $1.5 million was primarily due to an increase of $6.8 million related to clinical expenses and drug manufacturing, including costs associated with advancing the DENALI and ASPENOVA trials. This increase was partially offset by decreases of $3.9 million for personnel expense, of which $1.2 million was non-cash stock-based compensation, a decrease of $1.2 million related to a one-time impairment charge recorded in Q1 2025, and a decrease of $0.2 million for allocated overhead. General and Administrative Expenses: General and administrative expenses for the three months ended March 31, 2026 were $9.1 million, compared to $10.6 million during the three months ended March 31, 2025. This decrease of $1.5 million was attributable to a decrease of $2.0 million in personnel expense, of which $1.2 million was non-cash stock-based compensation. The decrease was partially offset by an increase of $0.5 million related to consulting, outside services and other allocated costs. Total Operating Expenses: Total operating expenses were $37.9 million for the three months ended March 31, 2026, compared to $45.6 million for the three months ended March 31, 2025. Total operating expenses for the first quarter of 2025 included a non-recurring $7.8 million expense associated with the strategic restructuring announced in January 2025. About Azenosertib Azenosertib is an investigational, potentially first-in-class, selective, and orally bioavailable inhibitor of WEE1 currently being evaluated in clinical studies in ovarian cancer and additional tumor types. WEE1 acts as a master regulator of the G1-S and G2-M cell cycle checkpoints, through negative regulation of both CDK1 and CDK2, to prevent replication of cells with damaged DNA. By inhibiting WEE1, azenosertib enables cell cycle progression, despite high levels of DNA damage, thereby resulting in the accumulation of DNA damage and leading to mitotic catastrophe and cancer cell death. Azenosertib is in late-stage development as a potential treatment for Cyclin E1-positive platinum-resistant ovarian cancer (PROC). There is currently no approved treatment option specifically for this biomarker-selected population which comprises approximately 50% of PROC patients. Cyclin E1 protein overexpression has been established as a sensitive and specific predictive biomarker for identifying patients who could potentially derive benefit from azenosertib treatment, based on retrospective analysis of azenosertib studies in PROC. Validation of the Cyclin E1 companion diagnostic assay is ongoing in the DENALI and ASPENOVA trials. Azenosertib has been granted Fast Track Designation by the U.S. FDA for the treatment of patients with Cyclin E1-positive platinum-resistant ovarian cancer. Fast Track Designation is intended to facilitate the development and expedite the review of therapies that have the potential to treat serious conditions and address unmet medical needs. About DENALI Clinical Trial DENALI is a multi-part Phase 2 registration-intended clinical trial (NCT05128825) studying azenosertib in PROC patients. Part 1b enrolled patients with PROC regardless of Cyclin E1 protein expression, all treated at 400mg QD 5:2. Part 2 is prospectively enrolling PROC patients with Cyclin E1 protein overexpression based on Zentalis' proprietary immunohistochemistry cutoff. Part 2, in total, is designed to support accelerated approval, pending positive study outcomes and further discussions with the FDA. The study design consists of the following parts: Part 2a: Dose confirmation evaluated two doses, 300mg QD 5:2 and 400mg QD 5:2, with approximately 30 patients enrolled per dose group. 400mg QD 5:2 was selected as the optimal monotherapy dose. Recruitment at the 300mg QD 5:2 dose level has been discontinued. All patients enrolled in Part 2a will contribute to the overall safety database submitted to the FDA. Part 2b: Enrollment expansion at the selected 400mg QD 5:2 dose up to approximately 100 patients, including patients at this dose in Part 2a. This cohort is currently enrolling. Part 2c: Broadening study population, which is expected to include approximately 40 patients previously treated with a taxane-containing regimen for PROC. This cohort is currently enrolling. Zentalis expects to complete enrollment in all cohorts of DENALI Part 2 (2a, 2b, 2c) and provide a topline readout by year-end 2026. For physician and patient information about the DENALI trial, please visit www.denalitrial.com. About ASPENOVA Clinical TrialASPENOVA is a Phase 3 randomized, confirmatory clinical trial designed to support full approval of azenosertib in patients with Cyclin E1-positive PROC. The trial is expected to enroll approximately 420 patients and compare azenosertib monotherapy at 400mg QD 5:2 to investigator's choice of standard-of-care single-agent chemotherapy (paclitaxel, pegylated liposomal doxorubicin [PLD], gemcitabine, or topotecan) in this biomarker-selected population. The primary endpoint is progression-free survival (PFS); key secondary endpoints include overall survival (OS) and overall response rate (ORR). The trial design was based on feedback from the U.S. FDA regarding requirements for seeking approval under the accelerated approval pathway and requirements to support potential conversion to full approval. About MUIR Clinical Trial MUIR (NCT04516447) is a multi-part, open-label Phase 1b clinical trial evaluating the safety, efficacy and preliminary clinical activity of azenosertib combinations in patients with ovarian cancer. Part 1 enrolled patients with platinum-resistant ovarian cancer (PROC) treated with azenosertib in combination with one of four chemotherapy regimens: carboplatin, gemcitabine, pegylated liposomal doxorubicin, or paclitaxel. Primary objectives are safety and tolerability, with key secondary objectives including clinical activity assessed by objective response rate, duration of response, and progression-free survival per RECIST v1.1. Part 2 is evaluating azenosertib plus bevacizumab as maintenance regimen (first [1L] or second line [2L]) in patients with advanced ovarian, peritoneal, or fallopian tube cancer following platinum-based chemotherapy. The dose expansion portion will evaluate azenosertib at the recommended dose in combination with bevacizumab in patients with platinum-sensitive ovarian cancer in 2L who progressed while on a PARP inhibitor for 1L maintenance. The primary objective is safety and tolerability; secondary objectives include preliminary clinical activity of the combination as assessed by progression-free survival for the dose expansion portion. The dose expansion portion is currently open for enrollment. About Zentalis PharmaceuticalsZentalis is a clinical oncology innovator developing a treatment approach for ovarian cancer and multiple tumor types. Leveraging therapeutics development and biomarker expertise, Zentalis is advancing monotherapy and combination studies of its investigational first-in-class WEE1 inhibitor, azenosertib. Focused on translating WEE1 science into clinical practice, we aim to equip physicians with a targeted, non-chemo, orally available medicine that enhances treatment experience, choice, and outcomes. Our mission: to unburden cancer patients with more convenience and care.​ For more information, please visit www.zentalis.com. Follow Zentalis on LinkedIn at www.linkedin.com/company/zentalis-pharmaceuticals. Forward-Looking StatementsThis press release contains forward-looking statements within the meaning of the U.S. Private Securities Litigation Reform Act of 1995, as amended. All statements contained in this press release that do not relate to matters of historical fact should be considered forward-looking statements, including, but not limited to, statements regarding the potential for azenosertib to be first-in-class; the continued development of azenosertib; the clinical and therapeutic potential of azenosertib, including the potential for azenosertib to be an important treatment option for patients with ovarian cancer or other indications; the Company’s biomarker-driven strategy for azenosertib; the potential to advance research on additional areas of opportunity for azenosertib as maintenance therapy in ovarian cancer and to explore additional tumor types; the Company’s anticipated milestones and the timing thereof, including the anticipated enrollment completion of DENALI Part 2, the topline readout from DENALI Part 2, and the design, conduct and timing of our confirmatory APSENOVA Phase 3 and MUIR Phase 1b trials; the Company’s anticipated cash runway; and the Company’s planned regulatory strategy for azenosertib and the timing thereof, including the potential for DENALI Part 2 to support an accelerated approval and for ASPENOVA to support conversion to a full approval and ex-US approval. The terms “anticipate,” “advance,” “believe,” “continue,” “design,” “develop,” “expect,” “focus,” “intend,” “plan,” “potential,” “runway,” “strategy,” “target,” and “will” and similar references are intended to identify forward-looking statements, although not all forward-looking statements contain these identifying words. These statements are neither promises nor guarantees, but involve known and unknown risks, uncertainties and other important factors that may cause our actual results, performance or achievements to be materially different from any future results, performance or achievements expressed or implied by the forward-looking statements, including, but not limited to, the following: our limited operating history, which may make it difficult to evaluate our current business and predict our future success and viability; we have and expect to continue to incur significant losses; our need for additional funding, which may not be available; our substantial dependence on the success of azenosertib; our plans, including the costs thereof, of development of a companion diagnostic; risks relating to the regulatory approval process or ongoing regulatory obligations; the outcome of preclinical testing and early trials may not be predictive of the success of later clinical trials; potential unforeseen events during clinical trials could cause delays or other adverse consequences; our product candidates may cause serious adverse side effects; the interim, initial, “topline,” and preliminary data from our clinical trials may change as more patient data becomes available, and are subject to audit and verification procedures that could result in material changes in the final data;; our reliance on third parties; effects of significant competition; the possibility of system failures or security breaches; risks relating to intellectual property; our ability to attract, retain and motivate qualified personnel, and risks relating to management transitions; significant costs as a result of operating as a public company; and the other important factors discussed under the caption “Risk Factors” in our most recently filed periodic report on Form 10-K or 10-Q and subsequent filings with the U.S. Securities and Exchange Commission (SEC) and our other filings with the SEC. Any such forward-looking statements represent management’s estimates as of the date of this press release. While we may elect to update such forward-looking statements at some point in the future, we disclaim any obligation to do so, even if subsequent events cause our views to change. ZENTALIS® and its associated logo are trademarks of Zentalis and/or its affiliates. All website addresses and other links in this press release are for information only and are not intended to be an active link or to incorporate any website or other information into this press release.  Contact:Aron FeingoldVP, Investor Relations & Corporate [email protected]

On track for DENALI Part 2a dose confirmation in 1H 2026 DENALI Part 2 trial topline readout expected by year end 2026; potential to support accelerated approval On track to initiate the ASPENOVA Phase 3, randomized, confirmatory trial in 1H 2026 Expanding azenosertib potential in ovarian cancer with the ongoing MUIR Part 2 trial evaluating the combination of azenosertib and bevacizumab as maintenance therapy $245.9 million cash, cash equivalents and marketable securities balance as of December 31, 2025, with projected cash runway into late 2027 SAN DIEGO, March 26, 2026 (GLOBE NEWSWIRE) -- Zentalis® Pharmaceuticals, Inc. (Nasdaq: ZNTL), a clinical oncology innovator advancing late-stage development of investigational first-in-class WEE1 inhibitor azenosertib as a biomarker-driven treatment approach for ovarian cancer, today announced financial results for the year ended December 31, 2025, and highlighted recent corporate accomplishments and milestones expected for 2026. “The completion of enrollment for DENALI Part 2a represented a key milestone to enable dose confirmation in the first half of 2026, with topline DENALI Part 2 trial readout anticipated by year-end. Results from the DENALI Part 2 trial could potentially support accelerated approval, pending study outcome,” said Julie Eastland, Chief Executive Officer. “In parallel, we expect to initiate the randomized Phase 3 confirmatory trial to support potential full approval, known as ASPENOVA, in the first half of 2026. The ASPENOVA trial will compare azenosertib to the current standard-of-care single, agent chemotherapy in the Cyclin E1+ PROC population. Beyond the lead indication Cyclin E1-positive platinum-resistant ovarian cancer (PROC), Zentalis is investigating azenosertib in combination with bevacizumab in earlier treatment settings for ovarian cancer in our MUIR study, and we plan to explore additional tumor types where WEE1 inhibition may have therapeutic relevance.” “2026 is expected to be a defining year for Zentalis. With a strong financial foundation, we continue to focus on advancing azenosertib, a potentially first-in-class, non-chemotherapy, oral treatment for patients with Cyclin E1-positive PROC – a group with substantial unmet medical needs.” Ms. Eastland added. Program Updates DENALI: Completed enrollment in DENALI Part 2a, supporting registration-intended development of azenosertib in Cyclin E1-positive PROC. The Company completed enrollment in Part 2a of the Phase 2 DENALI clinical trial (NCT05128825) in 2025. Part 2a is designed to confirm the recommended pivotal study dose for azenosertib monotherapy in Cyclin E1-positive PROC with a target enrollment of up to approximately 30 patients at each of two dose levels with an intermittent single, daily dosing with five days on, two days off dosing schedule: 400mg QD 5:2 and 300mg QD 5:2. ASPENOVA: Aligned with the FDA on Phase 3 ASPENOVA trial design. The Company aligned with the FDA on the design for ASPENOVA, a Phase 3 randomized, confirmatory trial of azenosertib vs. standard-of-care chemotherapy in patients with Cyclin E1-positive PROC to support full approval and meet requirements for the accelerated approval pathway. MUIR: Evaluating the combination of azenosertib and bevacizumab as maintenance therapy in ovarian cancer. MUIR (NCT04516447) is an open-label, phase 1b study, evaluating azenosertib combination regimens in patients with ovarian cancer. Part 1 studied azenosertib in combination with various chemotherapies in PROC patients. In Part 2, azenosertib is studied in combination with bevacizumab as maintenance therapy in patients with ovarian cancer. The Company presented a trial-in-progress e-poster on MUIR Part 2 at the 2026 European Society of Gynecological Oncology annual meeting. Anticipated 2026 Milestones Dose confirmation for azenosertib monotherapy in Cyclin E1-positive PROC expected in the 1H 2026. Phase 3 ASPENOVA trial is expected to initiate in the 1H 2026. DENALI Part 2 topline trial readout on track and expected by year end 2026. DENALI Part 2, if successful, has the potential to support accelerated approval, subject to FDA feedback. Full Year 2025 Financial Results Cash, Cash Equivalents and Marketable Securities: As of December 31, 2025, the Company had cash, cash equivalents and marketable securities of $245.9 million. The Company believes that its existing cash, cash equivalents and marketable securities as of December 31, 2025 will be sufficient to fund its operating expenses and capital expenditure requirements into late 2027, beyond anticipated DENALI topline trial readout. Research and Development Expenses: Research and development, or R&D, expenses for the year ended December 31, 2025 were $107.3 million, compared to $167.8 million for the year ended December 31, 2024. The decrease of $60.5 million was primarily due to decreases of $22.3 million for clinical expenses, $12.9 million for lab services, $8.8 million for drug manufacturing, and $1.3 million for supplies and other expenses. A decrease of $16.4 million from personnel expense, of which $6.5 million was non-cash stock-based compensation, also contributed to the overall reduction in research and development expenses. These decreases were partially offset by an increase of $1.2 million from a one-time, non-cash impairment charge recorded on research and development equipment during the first quarter ended March 31, 2025. General and Administrative Expenses: General and administrative expenses for the year ended December 31, 2025, were $37.7 million, compared to $87.1 million during the year ended December 31, 2024. The decrease of $49.4 million was primarily due to a decrease of $47.1 million of personnel expense, of which $40.8 million was non-cash stock-based compensation. Decreases of $3.3 million related to consulting and outside services also contributed to the overall reduction in general and administrative expenses. These decreases were partially offset by an increase of $1.0 million related to allocated and other costs. About Azenosertib Azenosertib is an investigational, potentially first-in-class, selective, and orally bioavailable inhibitor of WEE1 currently being evaluated in clinical studies in ovarian cancer and additional tumor types. WEE1 acts as a master regulator of the G1-S and G2-M cell cycle checkpoints, through negative regulation of both CDK1 and CDK2, to prevent replication of cells with damaged DNA. By inhibiting WEE1, azenosertib enables cell cycle progression, despite high levels of DNA damage, thereby resulting in the accumulation of DNA damage and leading to mitotic catastrophe and cancer cell death. Azenosertib is in late-stage development as a potential treatment for Cyclin E1-positive platinum-resistant ovarian cancer (PROC). There is currently no approved treatment option specifically for this biomarker-selected population which comprises approximately 50% of PROC patients. Cyclin E1 protein overexpression has been established as a sensitive and specific predictive biomarker for identifying patients who could potentially derive benefit from azenosertib treatment, based on retrospective analysis of azenosertib studies in PROC. Validation of the Cyclin E1 companion diagnostic assay is ongoing in the DENALI and ASEPENOVA trials. About DENALI Clinical Trial DENALI is a multi-part Phase 2 registration-intent clinical trial (NCT05128825) studying azenosertib in platinum-resistant ovarian cancer (PROC) patients. Part 1b enrolled patients with PROC regardless of Cyclin E1 protein expression, all treated at 400mg QD 5:2 (intermittent single, daily dosing with five days on, two days off dosing schedule). Interim results from Part 1b were presented at the Society of Gynecologic Oncology (SGO) 2025 Annual Meeting. Part 2 is prospectively enrolling PROC patients with Cyclin E1 protein overexpression based on Zentalis' proprietary immunohistochemistry cutoff. Part 2 includes Part 2a, a dose confirmation portion evaluating two doses, 300mg QD 5:2 and 400mg QD 5:2, and Part 2b, a portion designed to complete enrollment at the selected dose informed by Part 2a results. The trial design was aligned with the U.S. Food and Drug Administration (FDA). Part 2, in total, is designed for accelerated approval, pending study outcome and discussions with the FDA. About Zentalis Pharmaceuticals Zentalis is a clinical oncology innovator developing a treatment approach for ovarian cancer and multiple tumor types. Leveraging therapeutics development and biomarker expertise, Zentalis is advancing monotherapy and combination studies of its first-in-class WEE1 inhibitor, azenosertib. Focused on translating WEE1 science into clinical practice, we aim to equip physicians with a targeted, non-chemo, orally available medicine that enhances treatment experience, choice, and outcomes. Our mission: to unburden cancer patients with more convenience and care. For more information, please visit www.zentalis.com. Follow Zentalis on LinkedIn at www.linkedin.com/company/zentalis-pharmaceuticals. Forward-Looking Statements This press release contains forward-looking statements within the meaning of the U.S. Private Securities Litigation Reform Act of 1995, as amended. All statements contained in this press release that do not relate to matters of historical fact should be considered forward-looking statements, including, but not limited to, statements regarding the potential for azenosertib to be first-in-class; the significance of the referenced data on the late-stage development of azenosertib; the potential benefits of azenosertib, including the potential for azenosertib to be an important treatment option for patients with ovarian cancer or other indications; the broad potential of azenosertib; the Company’s biomarker-driven strategy for azenosertib; the potential to advance research on additional areas of opportunity for azenosertib as maintenance therapy in ovarian cancer and to explore additional tumor types; our anticipated milestones and the timing thereof, including the anticipated timing of DENALI Part 2a dose confirmation and the topline readout from DENALI Part 2, and the initiation, design, conduct and timing of our confirmatory APSENOVA Phase 3 trial; our anticipated cash runway; and our planned regulatory strategy for azenosertib and the timing thereof, including the potential for DENALI Part 2 to support an accelerated approval. The terms “anticipate,” “advance,” “believe,” “continues,” “design,” “develop,” “expect,” “intent,” “on track,” “plan,” “potential,” “runway,” “strategy,” “target,” and “will” and similar references are intended to identify forward-looking statements, although not all forward-looking statements contain these identifying words. These statements are neither promises nor guarantees, but involve known and unknown risks, uncertainties and other important factors that may cause our actual results, performance or achievements to be materially different from any future results, performance or achievements expressed or implied by the forward-looking statements, including, but not limited to, the following: our limited operating history, which may make it difficult to evaluate our current business and predict our future success and viability; we have and expect to continue to incur significant losses; our need for additional funding, which may not be available; our substantial dependence on the success of azenosertib; our plans, including the costs thereof, of development of a companion diagnostic; risks relating to the regulatory approval process or ongoing regulatory obligations; the outcome of preclinical testing and early trials may not be predictive of the success of later clinical trials; potential unforeseen events during clinical trials could cause delays or other adverse consequences; our product candidates may cause serious adverse side effects; inability to maintain our collaborations, or the failure of these collaborations; our reliance on third parties; effects of significant competition; the possibility of system failures or security breaches; risks relating to intellectual property; our ability to attract, retain and motivate qualified personnel, and risks relating to management transitions; significant costs as a result of operating as a public company; and the other important factors discussed under the caption “Risk Factors” in our most recently filed periodic report on Form 10-K or 10-Q and subsequent filings with the U.S. Securities and Exchange Commission (SEC) and our other filings with the SEC. Any such forward-looking statements represent management’s estimates as of the date of this press release. While we may elect to update such forward-looking statements at some point in the future, we disclaim any obligation to do so, even if subsequent events cause our views to change. ZENTALIS® and its associated logo are trademarks of Zentalis and/or its affiliates. All website addresses and other links in this press release are for information only and are not intended to be an active link or to incorporate any website or other information into this press release. Contact: Aron Feingold VP, Investor Relations & Corporate Communications [email protected]

DENALI Phase 2 trial evaluating azenosertib in patients with Cyclin E1-positive PROC remains on track with topline data anticipated by year end 2026, with the potential to support an accelerated approval, subject to FDA feedback $280.7 million cash, cash equivalents and marketable securities supports runway into late 2027 SAN DIEGO, Nov. 10, 2025 (GLOBE NEWSWIRE) -- Zentalis® Pharmaceuticals, Inc. (Nasdaq: ZNTL), a clinical-stage biopharmaceutical company developing a potentially first-in-class WEE1 inhibitor for patients with ovarian cancer and other tumor types, announced financial results for the third quarter 2025 and highlighted recent operational progress. "We are pleased with our continued disciplined execution of the DENALI clinical trial this quarter, supporting late-stage development of azenosertib as a potential treatment for Cyclin E1-positive platinum-resistant ovarian cancer, and positioning us for an anticipated topline data readout by year end 2026. Our engagement with trial investigators and presence at medical conferences is very encouraging and continues to support our development strategy," said Julie Eastland, Chief Executive Officer of Zentalis. "With $280.7 million in cash providing runway into late 2027, we maintain a robust financial foundation to deliver on our azenosertib objectives." Business Updates Phase 2 DENALI clinical trial remains on track and has the potential to support an accelerated approval, subject to FDA feedback. Enrollment is ongoing in DENALI Part 2a of the Phase 2 DENALI clinical trial (NCT05128825) of azenosertib in patients with Cyclin E1-positive PROC. DENALI Part 2a is designed to confirm the primary dose-of-interest with a target enrollment of up to approximately 30 patients at each of two dose levels: 400mg QD 5:2 (intermittent daily dosing with a five days on, two days off dosing schedule) and 300mg QD 5:2. DENALI Part 2b is designed to enroll approximately 70 patients at a single dose, the selection of which will be informed by the Part 2a results. The Company expects to disclose topline data from DENALI Part 2 (Part 2a and Part 2b) by year end 2026. We believe that DENALI Part 2, if successful, has the potential to support an accelerated approval, subject to FDA review. Poster Presentations at AACR-NCI-EORTC International Conference on Molecular Targets and Cancer Therapeutics support Cyclin E1 biomarker-driven strategy for azenosertib. Presentations feature data from first-in-human Phase 1 study, including Cyclin E1 biomarker findings, supporting late-stage development of azenosertib. TETON Phase 2 trial in uterine serous carcinoma (USC) completed enrollment. Consistent with the Company's previously announced strategic prioritization of azenosertib for the treatment of patients with Cyclin E1-positive PROC, further development in USC will be limited to partnering or the Company's ability to allocate capital to this indication. The Company will continue to support an ongoing investigator-initiated study to explore potential biomarker enrichment strategy in USC. Results from the TETON trial are planned for publication in the first half of 2026. Third Quarter 2025 Financial Results Cash, Cash Equivalents and Marketable Securities Position: As of September 30, 2025, the Company had cash, cash equivalents and marketable securities of $280.7 million. The Company believes that its existing cash, cash equivalents and marketable securities as of September 30, 2025 will be sufficient to fund its operating expenses requirements into late 2027. Research and Development Expenses: Research and development (R&D) expenses for the three months ended September 30, 2025 were $23.0 million, compared to $36.8 million for the three months ended September 30, 2024. The decrease of $13.8 million was primarily due to decreases of $7.6 million for personnel expenses, of which $2.7 million was non-cash stock-based compensation. Decreases of $4.2 million for lab services, $1.2 million for clinical expenses, and $0.8 million for supplies, overhead, and other expense also contributed to the overall reduction in research and development expenses. General and Administrative Expenses: General and administrative expenses for the three months ended September 30, 2025 were $10.8 million, compared to $14.6 million during the three months ended September 30, 2024. This decrease of $3.8 million was attributable to a decrease of $3.8 million in personnel expense, of which $2.8 million was non-cash stock-based compensation. Operating Expenses: Total operating expenses were $33.7 million for the three months ended September 30, 2025, compared to $51.4 million for the three months ended September 30, 2024. About Azenosertib Azenosertib is an investigational, novel, selective, and orally bioavailable inhibitor of WEE1 currently being evaluated as a monotherapy and combination clinical studies in ovarian cancer and additional tumor types. WEE1 acts as a master regulator of the G1-S and G2-M cell cycle checkpoints, through negative regulation of both CDK1 and CDK2, to prevent replication of cells with damaged DNA. By inhibiting WEE1, azenosertib enables cell cycle progression, despite high levels of DNA damage, thereby resulting in the accumulation of DNA damage and leading to mitotic catastrophe and cancer cell death. About DENALI Clinical Trial DENALI is a multi-part Phase 2 clinical trial studying azenosertib in platinum-resistant ovarian cancer (PROC) patients. Part 1b enrolled patients with PROC regardless of Cyclin E1 protein expression, all treated at 400mg 5:2 (intermittent daily dosing with a five days on, two days off dosing schedule). Interim results from Part 1b were presented at the Society of Gynecologic Oncology (SGO) 2025 Annual Meeting. Part 2 is ongoing and is enrolling PROC patients with Cyclin E1 protein overexpression based on Zentalis’ proprietary immunohistochemistry cutoff. Part 2 includes Part 2a, a dose confirmation portion evaluating two doses, 300mg 5:2 and 400mg 5:2, and Part 2b, a portion designed to complete enrollment at the selected dose. Part 2, in total, is designed for accelerated approval, pending study outcome and discussions with the U.S. Food and Drug Administration. About Zentalis Pharmaceuticals Zentalis® Pharmaceuticals, Inc. is a clinical-stage biopharmaceutical company developing azenosertib (ZN-c3), an investigational, potentially first-in-class and best-in-class WEE1 inhibitor for patients with Cyclin E1-positive platinum-resistant ovarian cancer (PROC). Azenosertib is being evaluated as a monotherapy and in combination across multiple tumor types in clinical trials and has broad franchise potential. In clinical trials, azenosertib has been well tolerated and has demonstrated anti-tumor activity as a single agent across multiple tumor types. The Company is also leveraging its extensive experience and capabilities to translate its science to advance research on additional areas of opportunity for azenosertib outside PROC. Zentalis has operations in San Diego. For more information, please visit www.zentalis.com. Follow Zentalis on LinkedIn at www.linkedin.com/company/zentalis-pharmaceuticals Forward-Looking Statements This press release contains forward-looking statements within the meaning of the U.S. Private Securities Litigation Reform Act of 1995, as amended. All statements contained in this press release that do not relate to matters of historical fact should be considered forward-looking statements, including, but not limited to, statements regarding the potential of azenosertib; our anticipated milestones and the timing thereof, including the anticipated timing of clinical data disclosures from DENALI Part 2 and TETON; the potential to advance research on additional areas of opportunity for azenosertib outside PROC, including any further development in USC; our anticipated cash runway; the potential for azenosertib to be first-in-class; the broad franchise potential of azenosertib; the planned design of our clinical trials, including DENALI Part 2; maintaining momentum and remaining on track relating to the execution of DENALI; and our planned clinical development strategy and regulatory strategy for azenosertib and the timing thereof, including the potential for DENALI Part 2 to support an accelerated approval. The terms “advance,” “anticipated,” “believe,” “continue,” “design,” “expect,” “opportunity,” “on track,” “plan,” “position,” “potential,” “runway,” “target,” and “will” and similar references are intended to identify forward-looking statements, although not all forward-looking statements contain these identifying words. These statements are neither promises nor guarantees, but involve known and unknown risks, uncertainties and other important factors that may cause our actual results, performance or achievements to be materially different from any future results, performance or achievements expressed or implied by the forward-looking statements, including, but not limited to, the following: our limited operating history, which may make it difficult to evaluate our current business and predict our future success and viability; we have and expect to continue to incur significant losses; our need for additional funding, which may not be available; our substantial dependence on the success of azenosertib; our plans, including the costs thereof, of development of companion diagnostics; the outcome of preclinical testing and early trials may not be predictive of the success of later clinical trials; failure to identify additional product candidates and develop or commercialize marketable products; potential unforeseen events during clinical trials could cause delays or other adverse consequences; risks relating to the regulatory approval process or ongoing regulatory obligations; failure to obtain U.S. or international marketing approval; our product candidates may cause serious adverse side effects; inability to maintain our collaborations, or the failure of these collaborations; our reliance on third parties; effects of significant competition; the possibility of system failures or security breaches; risks relating to intellectual property; our ability to attract, retain and motivate qualified personnel, and risks relating to management transitions; significant costs as a result of operating as a public company; and the other important factors discussed under the caption “Risk Factors” in our most recently filed periodic report on Form 10-K or 10-Q and subsequent filings with the U.S. Securities and Exchange Commission (SEC) and our other filings with the SEC. Any such forward-looking statements represent management’s estimates as of the date of this press release. While we may elect to update such forward-looking statements at some point in the future, we disclaim any obligation to do so, even if subsequent events cause our views to change. ZENTALIS® and its associated logo are trademarks of Zentalis and/or its affiliates. All website addresses and other links in this press release are for information only and are not intended to be an active link or to incorporate any website or other information into this press release. Contact: Aron Feingold VP, Investor Relations & Corporate Communications [email protected]

DENALI Phase 2 trial evaluating azenosertib in patients with Cyclin E1-positive PROC remains on track with topline data anticipated by year end 2026, with the potential to support an accelerated approval, subject to FDA feedback $303.4 million cash, cash equivalents and marketable securities supports operational runway into late 2027 SAN DIEGO, Aug. 06, 2025 (GLOBE NEWSWIRE) -- Zentalis® Pharmaceuticals, Inc. (Nasdaq: ZNTL), a clinical-stage biopharmaceutical company developing a potentially first-in-class and best-in-class WEE1 inhibitor for patients with ovarian cancer and other tumor types, announced financial results for the second quarter 2025 and highlighted recent operational progress. “This quarter, we continued to execute on our focused strategy to advance the late-stage clinical development of azenosertib in patients with Cyclin E1-positive platinum-resistant ovarian cancer (PROC). There is no approved treatment option specifically for this biomarker selected population, which comprises approximately 50% of PROC patients,” said Julie Eastland, Chief Executive Officer of Zentalis. “We are maintaining momentum with the DENALI Phase 2 clinical trial and remain on track to disclose topline data from DENALI Part 2 by year end 2026.” Business Updates Phase 2 DENALI clinical trial remains on track. Enrollment is ongoing in DENALI Part 2a of the Phase 2 DENALI clinical trial (NCT05128825) of azenosertib in patients with Cyclin E1-positive PROC. DENALI Part 2a is designed to confirm the primary dose-of-interest with a target enrollment of up to approximately 30 patients at each of two dose levels: 400mg QD 5:2 (intermittent daily dosing with a five days on, two days off dosing schedule) and 300mg QD 5:2. DENALI Part 2b is designed to enroll approximately 70 patients at a single dose, the selection of which will be informed by the Part 2a results, subject to FDA feedback. The Company expects to disclose topline data from DENALI Part 2 (Part 2a and Part 2b) by year end 2026. DENALI Part 2, if successful, has the potential to support an accelerated approval, subject to FDA review. Completed strategic restructuring announced in January 2025, supporting late-stage clinical development of azenosertib. The Company has operationally completed the restructuring and does not expect to incur further associated related non-recurring expenses. This restructuring prioritizes the late-stage development of azenosertib and extends the Company’s cash runway into late 2027, beyond the Company’s anticipated DENALI Part 2 topline data. Second Quarter 2025 Financial Results Cash, Cash Equivalents and Marketable Securities Position: As of June 30, 2025, the Company had cash, cash equivalents and marketable securities of $303.4 million, which includes $16.8 million representing the June 30, 2025 fair value of Immunome common stock received by the Company from the sale of its ROR1 antibody-drug conjugate (ADC) product candidate and ADC platform to Immunome in October 2024. The Company believes that its existing cash, cash equivalents and marketable securities as of June 30, 2025 will be sufficient to fund its operating expenses requirements into late 2027. Research and Development Expenses: Research and development (R&D) expenses for the three months ended June 30, 2025 were $27.6 million, compared to $48.4 million for the three months ended June 30, 2024. The decrease of $20.8 million was primarily due to decreases of $15.9 million for clinical expenses, $3.6 million for lab services, $3.4 million for drug manufacturing, $0.6 million related to personnel expenses and $0.4 million of miscellaneous expenses. These decreases were partially offset by an increase in companion diagnostic expense of $3.1 million. General and Administrative Expenses: General and administrative expenses for the three months ended June 30, 2025 were $8.4 million, compared to $16.7 million during the three months ended June 30, 2024. This decrease of $8.3 million was attributable to a decrease of $6.8 million in personnel expense, $1.1 million related to consulting and $0.4 million miscellaneous expenses. Operating Expenses: Total operating expenses were $36.1 million for the three months ended June 30, 2025, compared to $65.1 million for the three months ended June 30, 2024. About Azenosertib Azenosertib is a novel, selective, and orally bioavailable inhibitor of WEE1 currently being evaluated as a monotherapy and combination clinical studies in ovarian cancer and additional tumor types. WEE1 acts as a master regulator of the G1-S and G2-M cell cycle checkpoints, through negative regulation of both CDK1 and CDK2, to prevent replication of cells with damaged DNA. By inhibiting WEE1, azenosertib enables cell cycle progression, despite high levels of DNA damage, thereby resulting in the accumulation of DNA damage and leading to mitotic catastrophe and cancer cell death. About DENALI Clinical Trial DENALI is a multi-part Phase 2 clinical trial studying azenosertib in platinum-resistant ovarian cancer (PROC) patients. Part 1b enrolled patients with PROC regardless of Cyclin E1 protein expression, all treated at 400mg 5:2 (intermittent daily dosing with a five days on, two days off dosing schedule). Interim results from Part 1b were presented at the Society of Gynecologic Oncology (SGO) 2025 Annual Meeting. Part 2 is ongoing and is enrolling PROC patients with Cyclin E1 protein overexpression based on Zentalis’ proprietary immunohistochemistry cutoff. Part 2 includes Part 2a, a dose confirmation portion evaluating two doses, 300mg 5:2 and 400mg 5:2, and Part 2b, a portion designed to complete enrollment at the selected dose. Part 2, in total, is designed for accelerated approval, pending study outcome and discussions with the U.S. Food and Drug Administration. About Zentalis Pharmaceuticals Zentalis® Pharmaceuticals, Inc. is a clinical-stage biopharmaceutical company developing azenosertib (ZN-c3), a potentially first-in-class and best-in-class WEE1 inhibitor for patients with Cyclin E1-positive platinum-resistant ovarian cancer (PROC). Azenosertib is being evaluated as a monotherapy and in combination across multiple tumor types in clinical trials and has broad franchise potential. In clinical trials, azenosertib has been well tolerated and has demonstrated anti-tumor activity as a single agent across multiple tumor types. The Company is also leveraging its extensive experience and capabilities to translate its science to advance research on additional areas of opportunity for azenosertib outside PROC. Zentalis has operations in San Diego. For more information, please visit www.zentalis.com. Follow Zentalis on LinkedIn at www.linkedin.com/company/zentalis-pharmaceuticals Forward-Looking Statements This press release contains forward-looking statements within the meaning of the U.S. Private Securities Litigation Reform Act of 1995, as amended. All statements contained in this press release that do not relate to matters of historical fact should be considered forward-looking statements, including, but not limited to, statements regarding the potential of azenosertib; our anticipated milestones and the timing thereof, including the anticipated timing of clinical data disclosures; the potential to advance research on additional areas of opportunity for azenosertib outside PROC; our anticipated cash runway; the potential for azenosertib to be first-in-class and best-in-class; the broad franchise potential of azenosertib; the planned design of our clinical trials, including DENALI Part 2; maintaining momentum and remaining on track relating to the execution of DENALI; our planned clinical development strategy and regulatory strategy for azenosertib and the timing thereof, including the potential for DENALI Part 2 to support an accelerated approval; and our expectation to not incur further non-recurring expenses associated with the restructuring. The terms “advance,” “anticipated,” “believe,” “continue,” “design,” “expect,” “opportunity,” “potential,” “runway,” “target,” and “will” and similar references are intended to identify forward-looking statements, although not all forward-looking statements contain these identifying words. These statements are neither promises nor guarantees, but involve known and unknown risks, uncertainties and other important factors that may cause our actual results, performance or achievements to be materially different from any future results, performance or achievements expressed or implied by the forward-looking statements, including, but not limited to, the following: our limited operating history, which may make it difficult to evaluate our current business and predict our future success and viability; we have and expect to continue to incur significant losses; our need for additional funding, which may not be available; our substantial dependence on the success of azenosertib; our plans, including the costs thereof, of development of companion diagnostics; the outcome of preclinical testing and early trials may not be predictive of the success of later clinical trials; failure to identify additional product candidates and develop or commercialize marketable products; potential unforeseen events during clinical trials could cause delays or other adverse consequences; risks relating to the regulatory approval process or ongoing regulatory obligations; failure to obtain U.S. or international marketing approval; our product candidates may cause serious adverse side effects; inability to maintain our collaborations, or the failure of these collaborations; our reliance on third parties; effects of significant competition; the possibility of system failures or security breaches; risks relating to intellectual property; our ability to attract, retain and motivate qualified personnel, and risks relating to management transitions; significant costs as a result of operating as a public company; and the other important factors discussed under the caption “Risk Factors” in our most recently filed periodic report on Form 10-K or 10-Q and subsequent filings with the U.S. Securities and Exchange Commission (SEC) and our other filings with the SEC. Any such forward-looking statements represent management’s estimates as of the date of this press release. While we may elect to update such forward-looking statements at some point in the future, we disclaim any obligation to do so, even if subsequent events cause our views to change. ZENTALIS® and its associated logo are trademarks of Zentalis and/or its affiliates. All website addresses and other links in this press release are for information only and are not intended to be an active link or to incorporate any website or other information into this press release. Contact: Aron Feingold VP, Investor Relations & Corporate Communications [email protected]

First patient dosed in DENALI Part 2a clinical trial of azenosertib in patients with Cyclin E1+ PROC Topline data from DENALI Part 2 anticipated by year end 2026 with the potential to support an accelerated approval, subject to FDA feedback $332.5 million cash, cash equivalents and marketable securities supports operational runway into late 2027 SAN DIEGO, May 14, 2025 (GLOBE NEWSWIRE) -- Zentalis® Pharmaceuticals, Inc. (Nasdaq: ZNTL), a clinical-stage biopharmaceutical company developing a potentially first-in-class and best-in-class WEE1 inhibitor for patients with ovarian cancer and other tumor types, announced financial results for the first quarter 2025 and highlighted recent operational progress. "We continued advancement of azenosertib and made solid progress against our strategic goals in the first quarter. The initiation of DENALI Part 2 moves us into a new chapter as a late-stage development company focusing on a significant patient population in platinum-resistant ovarian cancer with limited choices," said Julie Eastland, Chief Executive Officer of Zentalis. “Our team remains focused on the enrollment and execution of DENALI. Zentalis is financially and organizationally well-positioned to continue advancing azenosertib as a potential treatment option for PROC patients.” Program Highlights First patient dosed in Part 2 of the Phase 2 DENALI clinical trial. In April 2025, the Company announced that the first patient had been dosed in Part 2a of the Phase 2 DENALI clinical trial (NCT05128825) of azenosertib in patients with Cyclin E1+ platinum-resistant ovarian cancer (PROC). Part 2a is designed to confirm the primary dose-of-interest with a target enrollment of approximately 30 patients at each of two dose levels: 400mg QD 5:2 and 300mg QD 5:2 (intermittent daily dosing with a five days on, two days off dosing schedule). The Company expects to disclose topline data from DENALI Part 2 (Part 2a and Part 2b) by year end 2026. DENALI Part 2, if successful, has the potential to support an accelerated approval, subject to FDA review. Azenosertib clinical data demonstrated clinically meaningful response rates and a consistent therapeutic profile. Previously disclosed clinical data from Part 1b of the DENALI study showed clinically meaningful results in patients with Cyclin E1+ PROC. As of the January 13, 2025 data cutoff, patients who were response-evaluable (n=43) had an objective response rate (ORR) of 34.9% and a median duration of response (mDOR) of 6.3 months. The mDOR is subject to change as there were patients with ongoing responses as of the cutoff date. Across multiple monotherapy studies of azenosertib with significant sample sizes, as of the December 2, 2024 data cutoff, azenosertib demonstrated meaningful antitumor activity (ORR >30% at 400mg QD 5:2) and a manageable safety profile in Cyclin E1+ PROC patients. Upcoming Events Zentalis plans to participate in the following scientific and medical conference: American Society of Clinical Oncology (ASCO) Annual Meeting – May 30 to June 3 in Chicago, IL NRG Oncology Summer Meeting – July 24 to 26 in Washington, D.C. Zentalis plans to participate and present in the following investor events: H.C. Wainwright 3rd Annual BioConnect Investor Conference – May 20 in New York, NY TD Cowen’s 6th Annual Oncology Innovation Summit – May 27 Virtual Jefferies Healthcare Conference – June 4 in New York, NY First Quarter 2025 Financial Results Cash, Cash Equivalents and Marketable Securities Position: As of March 31, 2025, the Company had cash, cash equivalents and marketable securities of $332.5 million, which includes $12.2 million representing the March 31, 2025 fair value of Immunome common stock received by the Company from the sale of its ROR1 antibody-drug conjugate (ADC) product candidate and ADC platform to Immunome in October 2024. The Company believes that its existing cash, cash equivalents and marketable securities as of March 31, 2025 will be sufficient to fund its operating expenses and capital expenditure requirements into late 2027. Research and Development Expenses: Research and development expenses for the three months ended March 31, 2025 were $27.2 million, compared to $49.6 million for the three months ended March 31, 2024. The decrease of $22.4 million was primarily due to decreases of $10.7 million for clinical expenses, $4.8 million for drug manufacturing, $3.5 million for lab services and $5.1 million related to consulting and personnel expenses, including non-cash stock-based compensation. These decreases were partially offset by a one-time impairment charge of $1.2 million related to the disposal of research and development equipment and an increase of $0.5 million of allocated overhead. General and Administrative Expenses: General and administrative expenses for the three months ended March 31, 2025 were $10.6 million, compared to $15.7 million during the three months ended March 31, 2024. This decrease of $5.1 million was primarily attributable to non-cash stock-based compensation. Operating Expenses: Total operating expenses were $45.6 million for the three months ended March 31, 2025, compared to $65.3 million for the three months ended March 31, 2024. Total operating expenses for the first quarter of 2025 include the non-recurring restructuring expenses of $7.8 million associated with the strategic restructuring announced in January 2025. About Azenosertib Azenosertib is a novel, selective, and orally bioavailable inhibitor of WEE1 currently being evaluated as a monotherapy and combination clinical studies in ovarian cancer and additional tumor types. WEE1 acts as a master regulator of the G1-S and G2-M cell cycle checkpoints, through negative regulation of both CDK1 and CDK2, to prevent replication of cells with damaged DNA. By inhibiting WEE1, azenosertib enables cell cycle progression, despite high levels of DNA damage, thereby resulting in the accumulation of DNA damage and leading to mitotic catastrophe and cancer cell death. About DENALI Clinical Trial DENALI is a multi-part Phase 2 clinical trial studying azenosertib in platinum-resistant ovarian cancer (PROC) patients. Part 1b enrolled patients with PROC regardless of Cyclin E1 protein expression, all treated at 400mg 5:2 (intermittent daily dosing with a five days on, two days off dosing schedule). Interim results from Part 1b were presented at the Society of Gynecologic Oncology (SGO) 2025 Annual Meeting. Part 2 is ongoing and is enrolling PROC patients with Cyclin E1 protein overexpression based on Zentalis’ proprietary immunohistochemistry cutoff. Part 2 includes Part 2a, a dose confirmation portion evaluating two doses, 300mg 5:2 and 400mg 5:2, and Part 2b, a portion designed to complete enrollment at the selected dose. Part 2, in total, is designed for accelerated approval, pending study outcome and discussions with the U.S. Food and Drug Administration. About Zentalis Pharmaceuticals Zentalis® Pharmaceuticals, Inc. is a clinical-stage biopharmaceutical company developing azenosertib (ZN-c3), a potentially first-in-class and best-in-class WEE1 inhibitor for patients with Cyclin E1+ platinum-resistant ovarian cancer (PROC). Azenosertib is being evaluated as a monotherapy and in combination across multiple tumor types in clinical trials and has broad franchise potential. In clinical trials, azenosertib has been well tolerated and has demonstrated anti-tumor activity as a single agent across multiple tumor types. The Company is also leveraging its extensive experience and capabilities to translate its science to advance research on additional areas of opportunity for azenosertib outside PROC. Zentalis has operations in San Diego. For more information, please visit www.zentalis.com. Follow Zentalis on X/Twitter at @ZentalisP and on LinkedIn at www.linkedin.com/company/zentalis-pharmaceuticals Forward-Looking Statements This press release contains forward-looking statements within the meaning of the U.S. Private Securities Litigation Reform Act of 1995, as amended. All statements contained in this press release that do not relate to matters of historical fact should be considered forward-looking statements, including, but not limited to, statements regarding the potential of azenosertib; our anticipated milestones and the timing thereof, including the anticipated timing of clinical data disclosures; the potential to advance research on additional areas of opportunity for azenosertib outside PROC; our anticipated cash runway; the potential for azenosertib to be first-in-class and best-in-class; the broad franchise potential of azenosertib; the planned design of our clinical trials, including DENALI Part 2; our positioning to execute; our planned clinical development strategy and regulatory strategy for azenosertib and the timing thereof, including the potential for DENALI Part 2 to support an accelerated approval; and our plans to participate in conferences and events. The terms “advance,” “anticipated,” “believe,” “continue,” “design,” “expect,” “goal,” “opportunity,” “plan,” “potential,” “progress,” “projected,” “runway,” “target,” “well-positioned,” and “will” and similar references are intended to identify forward-looking statements, although not all forward-looking statements contain these identifying words. These statements are neither promises nor guarantees, but involve known and unknown risks, uncertainties and other important factors that may cause our actual results, performance or achievements to be materially different from any future results, performance or achievements expressed or implied by the forward-looking statements, including, but not limited to, the following: our limited operating history, which may make it difficult to evaluate our current business and predict our future success and viability; we have and expect to continue to incur significant losses; our need for additional funding, which may not be available; our plans, including the costs thereof, of development of companion diagnostics; our substantial dependence on the success of azenosertib; the outcome of preclinical testing and early trials may not be predictive of the success of later clinical trials; failure to identify additional product candidates and develop or commercialize marketable products; potential unforeseen events during clinical trials could cause delays or other adverse consequences; risks relating to the regulatory approval process or ongoing regulatory obligations; failure to obtain U.S. or international marketing approval; our product candidates may cause serious adverse side effects; inability to maintain our collaborations, or the failure of these collaborations; our reliance on third parties; effects of significant competition; the possibility of system failures or security breaches; risks relating to intellectual property; our ability to attract, retain and motivate qualified personnel, and risks relating to management transitions; significant costs as a result of operating as a public company; and the other important factors discussed under the caption “Risk Factors” in our most recently filed periodic report on Form 10-K or 10-Q and subsequent filings with the U.S. Securities and Exchange Commission (SEC) and our other filings with the SEC. Any such forward-looking statements represent management’s estimates as of the date of this press release. While we may elect to update such forward-looking statements at some point in the future, we disclaim any obligation to do so, even if subsequent events cause our views to change. ZENTALIS® and its associated logo are trademarks of Zentalis and/or its affiliates. All website addresses and other links in this press release are for information only and are not intended to be an active link or to incorporate any website or other information into this press release. Contact: Aron Feingold VP, Investor Relations & Corporate Communications [email protected]

Positive azenosertib clinical data demonstrated clinically meaningful results in patients with Cyclin E1+ platinum-resistant ovarian cancer (PROC) Topline data from registration-intent DENALI Part 2 anticipated by year end 2026 Strengthened management team to support execution of highly focused strategy $371.1 million cash, cash equivalents and marketable securities balance as of December 31, 2024, with projected cash runway into late 2027 SAN DIEGO, March 26, 2025 (GLOBE NEWSWIRE) -- Zentalis® Pharmaceuticals, Inc. (Nasdaq: ZNTL), a clinical-stage biopharmaceutical company developing a potentially first-in-class and best-in-class WEE1 inhibitor for patients with ovarian cancer and other tumor types, today announced financial results for the year ended December 31, 2024, and highlighted recent corporate accomplishments. "Zentalis reported significant progress in the development of azenosertib in 2024 and made important advancements this year. We plan to maintain strong execution on the late-stage development of azenosertib," said Julie Eastland, Chief Executive Officer of Zentalis. “The clinical data we recently presented supports rapid advancement of azenosertib as a monotherapy therapy for patients with Cyclin E1+ PROC, and the continued development of azenosertib in other settings of ovarian cancer and other tumor types. With a sharpened focus on clinical development, and strong cash position into late 2027, Zentalis is well-positioned to execute on our objectives with the goal of bringing azenosertib to patients as quickly as possible.” Program Updates and Highlights Updated azenosertib monotherapy clinical data in DENALI Part 1b. Earlier this month, at the Society of Gynecologic Oncology’s 2025 Annual Meeting on Women’s Cancer, Zentalis presented updated clinical data from the DENALI (ZN-c3-005) Part 1b single-arm study evaluating azenosertib monotherapy 400mg QD 5:2 (intermittent daily dosing on a five-day on, two-day off schedule) in patients with Cyclin E1+ PROC tumors. As of the January 13, 2025 data cutoff, patients who were response-evaluable (n=43) had an objective response rate (ORR) of 34.9%, consistent with the Company’s interim results disclosed in January 2025, and an updated median duration of response (mDOR) of 6.3 months. The mDOR is subject to change since there were patients with ongoing responses as of the cutoff date. Clinically meaningful response rates in other azenosertib clinical trials disclosed on January 29, 2025. In the monotherapy arm of the MAMMOTH (ZN-c3-006) study, which evaluated azenosertib in patients with PARP-inhibitor resistant ovarian cancer, Cyclin E1+ patients treated at the primary dose-of interest 400mg QD 5:2 (n=16) had an ORR of 31.3% and an mDOR of 4.2 months as of the December 2, 2024 data cutoff. In the ZN-c3-001 Phase 1, dose-escalation study evaluating azenosertib monotherapy in solid tumors across continuous and intermittent dosing schedules, patients with Cyclin E1+ PROC treated at a total daily dose level ≥300mg at an intermittent schedule (n=23) demonstrated an encouraging ORR of 34.8% and an mDOR of 5.2 months as of the December 2, 2024 data cutoff. Azenosertib demonstrated strong and consistent therapeutic profile. Across all of the above studies, azenosertib demonstrated meaningful antitumor activity (ORR >30% at 400mg QD 5:2) and a manageable safety profile in Cyclin E1+ PROC patients, with a significant sample size as of the December 2, 2024 data cutoff. Aligned with FDA on study design for DENALI Part 2. As previously disclosed, the Company has aligned with the U.S. Food and Drug Administration (FDA) on the design of its DENALI Part 2 study in patients with Cyclin E1+ PROC, which allows for seamless enrollment across Parts 2a and 2b: Part 2a is designed to confirm the primary dose-of-interest, 400mg QD 5:2, with a target enrollment of approximately 30 patients at each of two dose levels: 400mg QD 5:2 and 300mg QD 5:2. Part 2b is designed to enroll approximately 70 additional patients at the selected dose, which will be informed by the Part 2a results, subject to FDA feedback. The Company plans to initiate enrollment of DENALI Part 2 in the first half of 2025 and to disclose topline data from DENALI Part 2 by year end 2026. DENALI Part 2, if successful, has the potential to support an accelerated approval, subject to FDA review. Zentalis plans to treat the same patient population in its Phase 3 randomized confirmatory study, which the Company plans to enroll concurrently with Part 2b, subject to FDA feedback. Continuing patient enrollment across clinical pipeline. The Company is continuing to enroll patients in its ZN-c3-002 Phase 1b dose escalation trial of azenosertib in the combination cohort with bevacizumab for the treatment of patients with platinum sensitive ovarian cancer. Additionally, the Company is continuing to enroll patients in its TETON (ZN-c3-004) Phase 2 clinical trial of azenosertib as a monotherapy for the treatment of uterine serous carcinoma and expects to present data from this study in the first half of 2026. Received Fast Track Designation for azenosertib. In January 2025, the Company announced that the FDA has granted Fast Track Designation for azenosertib for the treatment of patients with PROC who are positive for Cyclin E1 based on immunohistochemistry for protein levels. The FDA grants investigational medicines Fast Track Designation to facilitate the development and expedite the review of medicines that demonstrate the potential to treat serious conditions and fill an unmet medical need. Corporate Updates In November 2024, the Company strengthened its leadership and Board with the appointment of Julie Eastland as Chief Executive Officer, Ingmar Bruns, M.D. as Chief Medical Officer, Haibo Wang as Chief Business Officer, Wendy Chang as Chief People Officer and Scott Myers as Chairman of the Board. Together with the other members of the leadership team, the Company refined and sharpened its pipeline. In January 2025, the Company announced a strategic restructuring to support late-stage clinical development of azenosertib. This restructuring allows the Company to be more efficient in advancing the clinical development of azenosertib and extended the Company’s cash runway into late 2027, beyond the Company’s DENALI Part 2 topline data. The workforce reduction associated with the restructuring is expected to be substantially completed in the second quarter of 2025. Full Year 2024 Financial Results Cash, Cash Equivalents and Marketable Securities Position: As of December 31, 2024, the Company had cash, cash equivalents and marketable securities of $371.1 million, which includes $19.2 million representing the December 31, 2024 fair value of Immunome common stock received by the Company from the sale of its ROR1 antibody-drug conjugate (ADC) product candidate and ADC platform to Immunome in October 2024. The Company believes that its existing cash, cash equivalents and marketable securities as of December 31, 2024 will be sufficient to fund its operating expenses and capital expenditure requirements into late 2027. Research and Development Expenses: Research and development, or R&D, expenses for the year ended December 31, 2024 were $167.8 million, compared to $189.6 million for the year ended December 31, 2023. The decrease of $21.8 million was primarily due to a decrease of $10.7 million for personnel expense, of which $9.7 million is related to non-cash stock-based compensation. There were also decreases of $5.8 million for clinical, $4.5 million for allocable expenses and $4.3 million for consulting, outside services and other expenses. These decreases were partially offset by increases of $3.5 million as a result from changes in cost sharing with Zentera. General and Administrative Expenses: General and administrative expenses for the year ended December 31, 2024 were $87.1 million, compared to $64.4 million during the year ended December 31, 2023. The increase of $22.8 million was primarily attributable to a $27.1 million increase related to personnel expense, of which $22.2 million is related to non-cash stock-based compensation. The Company also had an increase of $3.1 million for facilities and allocable expenses. These increases were partially offset by a decrease of $4.9 million for a non-cash operating lease impairment charge during the twelve months ended December 31, 2023, and $2.5 million for outside services and other expenses. Operating Expenses: Total operating expenses were $258.6 million for the year ended December 31, 2024, compared to $299.5 million for the year ended December 31, 2023. Following the strategic restructuring announced in January 2025, the Company expects to incur the non-recurring expenses associated with the reorganization in the first quarter of 2025, and have reduced operating expenses in the remainder of 2025, supporting the anticipated cash runway into late 2027. About Azenosertib Azenosertib is a novel, selective, and orally bioavailable inhibitor of WEE1 currently being evaluated as a monotherapy and combination clinical studies in ovarian cancer and additional tumor types. WEE1 acts as a master regulator of the G1-S and G2-M cell cycle checkpoints, through negative regulation of both CDK1 and CDK2, to prevent replication of cells with damaged DNA. By inhibiting WEE1, azenosertib enables cell cycle progression, despite high levels of DNA damage, thereby resulting in the accumulation of DNA damage and leading to mitotic catastrophe and cancer cell death. About Zentalis Pharmaceuticals Zentalis® Pharmaceuticals, Inc. is a clinical-stage biopharmaceutical company developing azenosertib (ZN-c3), a potentially first-in-class and best-in-class WEE1 inhibitor for patients with Cyclin E1+ platinum-resistant ovarian cancer (PROC). Azenosertib is being evaluated as a monotherapy and in combination across multiple tumor types in clinical trials and has broad franchise potential. In clinical trials, azenosertib has been well tolerated and has demonstrated anti-tumor activity as a single agent across multiple tumor types. The Company is also leveraging its extensive experience and capabilities to translate its science to advance research on additional areas of opportunity for azenosertib outside PROC. Zentalis has operations in San Diego. For more information, please visit www.zentalis.com. Follow Zentalis on X/Twitter at @ZentalisP and on LinkedIn at www.linkedin.com/company/zentalis-pharmaceuticals Forward-Looking Statements This press release contains forward-looking statements within the meaning of the U.S. Private Securities Litigation Reform Act of 1995, as amended. All statements contained in this press release that do not relate to matters of historical fact should be considered forward-looking statements, including, but not limited to, statements regarding the potential of azenosertib; our anticipated milestones and the timing thereof, including the anticipated timing of initiation of clinical trials and timing of clinical data disclosures; the potential to advance research on additional areas of opportunity for azenosertib outside PROC; our anticipated cash runway; the potential for azenosertib to be first-in-class and best-in-class; the broad franchise potential of azenosertib; our plans to rapidly advance azenosertib as a monotherapy therapy for patients with Cyclin E1+ PROC and our plans to continue developing azenosertib in other settings of ovarian cancer and other tumor types; the estimated timing and impact of our strategic restructuring; our ability to recognize the benefits of our strategic restructuring; the planned design of our clinical trials, including target enrollment numbers; the potential for DENALI Part 2 to be registrational and support an accelerated approval for azenosertib; our positioning to execute; our goal of bringing azenosertib to patients as quickly as possible; our plan to maintain strong execution on the late-stage development of azenosertib; our plans with respect to a Phase 3 confirmatory study of azenosertib in Cyclin E1+ PROC patients; our expectations regarding our expenses; and our planned clinical development strategy and regulatory strategy for azenosertib and the timing thereof, including plans for registration-intent studies and the potential for accelerated approval. The terms “advance,” “anticipated,” “believe,” “beyond,” “continue,” “design,” “expect,” “goal,” “intent,” “opportunity,” “plan,” “potential,” “progress,” “projected,” “target,” and “will” and similar references are intended to identify forward-looking statements, although not all forward-looking statements contain these identifying words. These statements are neither promises nor guarantees, but involve known and unknown risks, uncertainties and other important factors that may cause our actual results, performance or achievements to be materially different from any future results, performance or achievements expressed or implied by the forward-looking statements, including, but not limited to, the following: our limited operating history, which may make it difficult to evaluate our current business and predict our future success and viability; we have and expect to continue to incur significant losses; our need for additional funding, which may not be available; our plans, including the costs thereof, of development of companion diagnostics; our substantial dependence on the success of azenosertib; the outcome of preclinical testing and early trials may not be predictive of the success of later clinical trials; failure to identify additional product candidates and develop or commercialize marketable products; potential unforeseen events during clinical trials could cause delays or other adverse consequences; risks relating to the regulatory approval process or ongoing regulatory obligations; failure to obtain U.S. or international marketing approval; our product candidates may cause serious adverse side effects; inability to maintain our collaborations, or the failure of these collaborations; our reliance on third parties; effects of significant competition; the possibility of system failures or security breaches; risks relating to intellectual property; our ability to attract, retain and motivate qualified personnel, and risks relating to management transitions; significant costs as a result of operating as a public company; and the other important factors discussed under the caption “Risk Factors” in our most recently filed periodic report on Form 10-K or 10-Q and subsequent filings with the U.S. Securities and Exchange Commission (SEC) and our other filings with the SEC. Any such forward-looking statements represent management’s estimates as of the date of this press release. While we may elect to update such forward-looking statements at some point in the future, we disclaim any obligation to do so, even if subsequent events cause our views to change. ZENTALIS® and its associated logo are trademarks of Zentalis and/or its affiliates. All website addresses and other links in this press release are for information only and are not intended to be an active link or to incorporate any website or other information into this press release. Contact: Haibo Wang - Chief Business Officer Ron Moldaver - Investor Relations [email protected]