Zai Lab to Present Data from Phase 1 Trial of DLL3-Targeted Antibody-Drug Conjugate (ADC) ZL-1310 at 2025 ASCO Annual Meeting

- Zai Lab will highlight potential of ZL-1310 as a promising, best-in-class Delta-like ligand (DLL3-targeted) ADC for patients with extensive-stage small cell lung cancer (ES-SCLC)

- Investor conference call and webcast to discuss data and clinical trial plans on June 2, 2025, at 7:00 a.m. CT / 8:00 a.m. ET / 8:00 p.m. HKT

Zai Lab Limited (NASDAQ: ZLAB; HKEX: 9688) today announced that updated data from an ongoing, global Phase 1a/1b clinical trial (NCT06179069) evaluating ZL-1310, the Company’s potential first-in-class and best-in-class, Delta-like ligand (DLL3) antibody-drug conjugate (ADC) for the treatment of extensive-stage small cell lung cancer (ES-SCLC), will be presented during a poster session at the 2025 American Society of Clinical Oncology (ASCO) Annual Meeting taking place May 30-June 3, 2025 in Chicago, Illinois. The updated results will include additional patients and follow-up from the ongoing trial of ZL-1310 in patients with previously treated ES-SCLC after at least one prior platinum-based chemotherapy regimen.

“ZL-1310 reflects our company’s commitment to develop differentiated oncology therapies that address current limitations with many first-generation and current standard-of-care treatments,” said Rafael G. Amado, M.D., President, Head of Global Research and Development, Zai Lab. “We are focused on the development of ZL-1310, and we look forward to presenting updated results at ASCO 2025.”

Details regarding the webcast and conference call are as follows:

Zai Lab will hold an investor conference call and webcast to highlight updated ZL-1310 data at ASCO and outline the next steps in clinical development.

Date/Time: Monday, June 2, 2025, at 7:00 a.m. CT / 8:00 a.m. ET / 8:00 p.m. HKT, please register at:

Webcast presentation (preferred): https://edge.media-server.com/mmc/p/jnqqzjod;

Dial-in: https://register-conf.media-server.com/register/BIc7326906f3764306accd7708d21d2ecb.

Presenter: Rafael G. Amado, M.D., President, Head of Global Research and Development, Zai Lab

Details regarding the ZL-1310 poster presentation are as follows:

Title: ZL-1310, a DLL3 ADC, in patients with extensive stage small cell lung cancer: Ph1 trial update

Presenter: Manish R. Patel, M.D., Florida Cancer Specialists/Sarah Cannon Research Institute, Sarasota, FL

Session Title: Poster Session - Developmental Therapeutics - Molecularly Targeted Agents and Tumor Biology

Date/Time: Monday, June 2, 2025, from 1:30 p.m. - 4:30 p.m. CT

Location: McCormick Place Convention Center, Hall A – Posters and Exhibits

Published Abstract Number: 3041

Poster Board: 356

About Small Cell Lung Cancer and ZL-1310

Small cell lung cancer (SCLC) is one of the most aggressive and lethal solid tumors, accounting for ~15% of the approximately 2.5 million patients diagnosed with lung cancer worldwide each year^1,2. Additionally, two-thirds of all SCLC patients are diagnosed at extensive stage³.

DLL3 is an antigen overexpressed in many neuroendocrine tumors, such as SCLC, and is often associated with poor clinical outcomes. ZL-1310 comprises a humanized anti-DLL3 monoclonal antibody connected via a cleavable linker to a novel camptothecin derivative (a topoisomerase 1 inhibitor) as its payload. The compound was designed with a novel ADC technology platform called TMALIN^®, which leverages the tumor microenvironment to overcome challenges associated with first-generation ADC therapies.

ZL-1310 received an Orphan Drug Designation from the U.S. Food and Drug Administration (FDA) in January 2025, recognizing its potential to treat patients with SCLC.

About the Webcast and Conference Call

All participants must use the link provided above to complete the online registration process in advance of the conference call. Dial-in details will be in the confirmation email which the participant will receive upon registering.

A replay will be available shortly after the call and can be accessed by visiting the Company's website.

About Zai Lab

Zai Lab (NASDAQ: ZLAB; HKEX: 9688) is an innovative, research-based, commercial-stage biopharmaceutical company based in China and the United States. We are focused on discovering, developing, and commercializing innovative products that address medical conditions with significant unmet needs in the areas of oncology, immunology, neuroscience and infectious disease. Our goal is to leverage our competencies and resources to positively impact human health worldwide.

For additional information about Zai Lab, please visit www.zailaboratory.com or follow us at www.X.com/ZaiLab_Global, www.twitter.com/ZaiLab_Global.

Zai Lab Forward-Looking Statements

This press release contains forward-looking statements relating to our future expectations, plans, and prospects, for Zai Lab, including, without limitation, statements relating to our prospects and plans for developing and commercializing next generation ADCs, including ZL-1310, the potential benefits of ZL-1310, and the potential treatment of SCLC and neuroendocrine tumors. These forward-looking statements may contain words such as “aim,” “anticipate,” “believe,” “could,” “estimate,” “expect,” “forecast,” “goal,” “intend,” “may,” “plan,” “possible,” “potential,” “will,” “would,” and other similar expressions. Such statements constitute forward-looking statements within the meaning of the Private Securities Litigation Reform Act of 1995. Forward-looking statements are not statements of historical fact or guarantees or assurances of future performance. Forward-looking statements are based on our expectations and assumptions as of the date of this press release and are subject to inherent uncertainties, risks, and changes in circumstances that may differ materially from those contemplated by the forward-looking statements. Actual results may differ materially from those indicated by such forward-looking statements as a result of various important factors, including but not limited to (1) our ability to successfully commercialize and generate revenue from our approved products, (2) our ability to obtain funding for our operations and business initiatives, (3) the results of our clinical and pre-clinical development of our product candidates, (4) the content and timing of decisions made by the relevant regulatory authorities regarding regulatory approvals of our product candidates, (5) risks related to doing business in China, and (6) other factors identified in our most recent annual and quarterly reports and in other reports we have filed with the U.S. Securities and Exchange Commission (SEC). We anticipate that subsequent events and developments will cause our expectations and assumptions to change, and we undertake no obligation to update or revise any forward-looking statements, whether as a result of new information, future events, or otherwise, except as may be required by law. These forward-looking statements should not be relied upon as representing our views as of any date subsequent to the date of this press release.

Our SEC filings can be found on our website at www.zailaboratory.com and on the SEC’s website at www.sec.gov.

References:

¹ J Thorac Oncol. 2023 Jan;18(1):31-46; Lung Cancer Foundation of America.

² WHO Globocan 2022.

³ Sabari JK, et al. Nat Rev Clin Oncol. 2017;14:549-561.

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