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zentalis Zentalis Pharmaceuticals Reports First Quarter 2021 Financial Results and Operational Update May 17 , 2021 Reported robust initial results from the Phase 1 monotherapy dose escalation trial of its WEE1 inhibitor , ZN - c3 , demonstrating single - agent activity and Exceptional Responses in heavily pre - treated patients Announced clinical collaboration with GlaxoSmithKline ( GSK ) to evaluate ZN - c3 in combination with niraparib , a PARP inhibitor Upcoming milestone review of its clinical product candidates ZN - c5 and ZN - c3 NEW YORK and SAN DIEGO , May 17 , 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 financial results for the first quarter ended March 31 , 2021 and highlighted recent corporate accomplishments . " This quarter , we have made tremendous progress advancing the clinical development of one of our lead programs , ZN - c3 , underscored by strong data recently presented in a late - breaking session at AACR , " commented Dr. Anthony Sun , Chairman and Chief Executive Officer of Zentalis . " These initial results from the Phase 1 monotherapy trial not only demonstrated signals of single - agent efficacy and a superior safety profile compared to other WEE1 inhibitors in development , but also generated multiple confirmed Exceptional Responses across differing solid tumor types . With the recommended dose selected , we look forward to pursuing many planned trials with ZN - c3 this year and exploring its best - in - class potential both as a monotherapy and in combination . " Continued Dr. Sun , " In parallel , we continue to make great headway with the development of our additional differentiated oncology candidates - ZN - c5 , ZN - d5 and ZN - e4 - with numerous trials on track to initiate in 2021. Looking ahead to our catalyst - rich year , we remain focused on executing on our clinical strategy and creating value for our stakeholders , in hopes of delivering innovative treatments to help improve the lives of cancer patients . " Program Highlights : • In April 2021 , Zentalis reported initial results from the Phase 1 portion of a Phase 1/2 trial of ZN - c3 in advanced solid tumors in a late - breaking session at the American Association of Cancer Research ( AACR ) Annual Meeting , which was further discussed at a webcast event with Key Opinion Leaders . ■ ZN - c3 generated three Exceptional Responses in heavily pretreated patients with ovarian cancer , colorectal cancer and non - small cell lung cancer , as well as two unconfirmed Partial Responses in patients with uterine serous carcinoma ; ■ Showcased favorable safety results with a wide therapeutic window ; ■ A Unique Predictive Biomarker was identified for the Exceptional Responders , with plans to further investigate the biomarker in this patient population ; ■ Selected Recommended Phase 2 Dose for ZN - c3 to be 300 mg QD with continuous dosing . • In April 2021 , we entered into a Clinical Trial Collaboration and Supply Agreement with GSK to investigate the combination of ZN - c3 , our oral WEE1 inhibitor , and niraparib , GSK's poly ( ADP - ribose ) polymerase ( PARP ) inhibitor , in patients with advanced epithelial ovarian cancer . The Company expects to initiate a Phase 1b trial with this combination in the second half of 2021 . • Zentera Therapeutics , Zentalis ' majority - owned joint venture , filed four Clinical Trial Applications ( CTAs , China equivalent of IND ) and three have been approved in China to date for ZN - c5 , ZN - c3 , and ZN - c3 in combination . A fourth CTA was submitted earlier this month for ZN - d5 . • In February 2021 , Zentalis entered into a strategic collaboration with Tempus to leverage its patient - derived organoid biological modeling platform to aid Zentalis in discovering and developing novel oncology therapies . The collaboration will assist in the validation of Zentalis ' mechanistic discoveries , initially focusing on its WEE1 inhibitor , ZN - c3 , across patient tumor populations . Anticipated Milestones : • The Company plans to report interim results from numerous ongoing trials with ZN - c5 and to share guidance on future development plans for this product candidate in the second quarter of 2021 . • Zentalis expects to initiate several studies in the coming months , including : • A Phase 2 trial of ZN - c3 in uterine serous carcinoma in the third quarter of 2021 ;