Zentalis Pharmaceuticals Enters into Clinical Collaboration and Supply Agreement with GlaxoSmithKline to Evaluate its Oral WEE1 Inhibitor, ZN-c3, in Combination with Niraparib, a PARP Inhibitor

NEW YORK and SAN DIEGO, April 12, 2021 (GLOBE NEWSWIRE) -- Zentalis Pharmaceuticals, Inc. (Nasdaq: ZNTL), a clinical-stage biopharmaceutical company focused on discovering and developing small molecule therapeutics targeting fundamental biological pathways of cancers, today announced a clinical collaboration agreement with GlaxoSmithKline (“GSK”) in which Zentalis will evaluate the combination of ZN-c3, Zentalis’ oral WEE1 inhibitor product candidate, and ZEJULA (niraparib), GSK’s poly (ADP-ribose) polymerase (PARP) inhibitor, in patients with advanced epithelial ovarian cancer. Zentalis is currently conducting clinical studies with ZN-c3 both as a monotherapy and in combination with certain standard of care therapies.

“This clinical collaboration and supply agreement with GSK allows us to investigate the broader potential of our WEE1 inhibitor when used as part of a combination treatment with niraparib, a PARP inhibitor,” commented Dr. Anthony Sun, Chairman and Chief Executive Officer of Zentalis Pharmaceuticals. “As demonstrated in our preclinical studies, ZN-c3 is designed to have significant advantages over other investigational WEE1 inhibitor therapies. We believe this combination has the potential to meaningfully improve the outcomes for patients with ovarian cancer.”

PARP inhibitors prevent DNA damage repair in cancer cells. Similar to PARP, WEE1 plays a role in cellular regulation and repair, allowing cells with DNA damage to repair and survive. Inhibition of WEE1 causes dysregulation of DNA replication and subsequently induces apoptosis. Based on these complementary mechanisms of action, the use of WEE1 and PARP inhibitors could potentially have synergistic anti-tumor activity.

More than 300,000 women worldwide are diagnosed with ovarian cancer each year, leading to over 180,000 fatalities¹. While substantial progress has been made in the treatment of this disease, there is an urgency to address the remaining unmet need through the development of innovative combination treatments.

Under the terms of the non-exclusive collaboration, Zentalis is responsible for conducting the study with GSK providing all required doses of niraparib. Zentalis maintains full ownership of ZN-c3.

¹www.cancerresearch.org

About ZN-c3

ZN-c3 is an oral inhibitor of WEE1 in development for the treatment of advanced solid tumors. The inhibition of WEE1, a DNA damage response protein, aims to generate sufficient DNA damage in cancer cells, causing cell death, thereby preventing tumor growth and potentially causing tumor regression. Zentalis is currently conducting a Phase 1/2 clinical trial in patients with advanced solid tumors and reported initial data from the Phase 1 portion at the AACR Annual Meeting 2021. In addition, the Company is also conducting a Phase 1b trial evaluating ZN-c3 in combination with chemotherapy in patients with advanced ovarian cancer, with plans to initiate a Phase 1/2 trial in combination with GSK’s niraparib in patients with advanced ovarian cancer, a Phase 1/2 trial in combination with chemotherapy in osteosarcoma and a Phase 2 trial investigating ZN-c3 as a monotherapy in patients with uterine serous carcinoma in 2021.

About ZEJULA (niraparib)

GSK’s ZEJULA (niraparib) is an FDA and EMA-approved oral, once-daily poly (ADP-ribose) polymerase inhibitor that is currently being evaluated in multiple pivotal trials. GSK is building a robust niraparib clinical development programme by assessing activity across multiple tumour types and by evaluating several potential combinations of niraparib with other therapeutics. The ongoing development programme for niraparib includes several combination studies, including Phase III studies in ovarian and non-ovarian indications.

About Zentalis

Zentalis Pharmaceuticals, Inc. is a clinical-stage biopharmaceutical company focused on discovering and developing small molecule therapeutics targeting fundamental biological pathways of cancers. The Company is developing a broad pipeline of potentially best-in-class oncology candidates, all internally discovered, which include ZN-c5, an oral selective estrogen receptor degrader (SERD) for ER+/HER2- breast cancer, ZN-c3, a WEE1 inhibitor for advanced solid tumors, ZN-d5, a BCL-2 inhibitor for hematologic malignancies, and ZN-e4, an EGFR inhibitor for non-small cell lung carcinoma (NSCLC). Zentalis has licensed ZN-c5, ZN-c3 and ZN-d5 to its majority-owned joint venture, Zentera Therapeutics, to develop and commercialize these candidates in China. Zentalis has operations in both New York and San Diego.

For more information, please visit www.zentalis.com. Follow Zentalis on 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 Private Securities Litigation Reform Act of 1995. All statements contained in this press release that do not relate to matters of historical fact should be considered forward-looking statements, including without limitation statements regarding our expectations surrounding the development, potential, safety, efficacy, and regulatory and clinical progress of our product candidates in the Unites States and globally, and activities in connection with our clinical collaboration agreement with GlaxoSmithKline. 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: the outbreak of the novel coronavirus disease, COVID-19, has adversely impacted and may continue to adversely impact our business, including our preclinical studies and clinical trials; 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 our lead product candidate; failure to identify additional product candidates and develop or commercialize marketable products; the early stage of our development efforts; 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 significant costs as a result of operating as a public company. These and other important factors discussed under the caption “Risk Factors” in our Annual Report on Form 10-K for the quarterly period ended December 31, 2020 filed with the U.S. Securities and Exchange Commission (SEC) and our other filings with the SEC could cause actual results to differ materially from those indicated by the forward-looking statements made in this press release. 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.

Investor Contact:

Thomas Hoffmann

Solebury Trout

1.646.378.2931

thoffmann@soleburytrout.com

Media Contact:

Julia Deutsch

Solebury Trout

1.646.378.2967

jdeutsch@soleburytrout.com