ZLAB Status Update Presentation

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Forward-Looking Statements This presentation contains forward-looking statements about future expectations, plans, and prospects for Zai Lab, including, without limitation, statements regarding product candidates in our pipeline including ZL-1310 and related clinical trials and preclinical studies, the potential benefits and safety and efficacy of ZL-1310, and the potential treatment of small cell lung cancer (SCLC) and other DLL3-expressing tumors. Theseforward- looking statements may contain words such as “aim,” “anticipate,” “believe,” “continue,” “could,” “estimate,” “expect,” “forecast,” “goal,” “intend,” “may,” “plan,” “possible,” “potential,” “target,” “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 presentation 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 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 discussed in our most recent annual and quarterly reports and 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 presentation. Our SEC filings can be found on our website at www.zailaboratory.com and on the SEC’s website at http://www.sec.gov. This presentation does not constitute an offer to sell or the solicitation of an offer to buy any securities of Zai Lab Limited.

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ZL-1310 (DLL3 ADC) Highlights from ASCO 2025 Next Steps and Conclusions Manish R. Patel, MD Director of Drug Development, Florida Cancer Specialists Associate Director of Drug Development, Sarah Cannon Research Institute Q&A with Dr. Amado and Dr. Spira 4 • Hematologist/Medical Oncologist • Subspecializes in Early Phase clinical trials based out of Sarasota, Florida • Directs three Phase 1 units as part of the Florida program and provides care for all malignancies on Phase 1 clinical trials • Received medical degree from the University of Miami School of Medicine and completed Internal Medicine residency training at Vanderbilt University in Nashville, TN • Fellowship in Hematology/Oncology at the H. Lee Moffitt Cancer Center & Research Institute/University of South Florida in Tampa, FL Agenda

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Structure of ZL-13104 A: Humanized anti-DLL3 IgG1 mAb B: Cleavable tripeptide-based linker C: Camptothecin derivative payload, C24; DAR=8 • Small cell lung cancer (SCLC) accounts for ~15% of the lung cancer overall with ~270,000 annual deaths worldwide with a high unmet medical need1-2 • SCLC is a high-grade neuroendocrine tumor with a high proliferation rate, early metastases, and poor prognosis3 • DLL3 is a validated target for neuroendocrine tumors and is highly expressed in SCLC4 • Zocilurtatug pelitecan or ZL-1310, a DLL3-targeted antibody drug conjugate (ADC), demonstrates promising clinical activity in patients with relapsed/refractory (r/r) ES-SCLC 5 - Potent topoisomerase 1 inhibitor payload - High picomolar antibody affinity - Drug-to-antibody ratio (DAR) of 8 - Stable, cleavable tripeptide-based linker - Strong bystander antitumor effect Notes: (1) Siegel RL et al. Cancer statistics, 2018. CA Cancer J Clin. 2018; 68:7-30; (2) Gazdar AF et al. Nat Rev Cancer. 2017;17(12):725-37.Rudin et al. Nat Rev Dis Primers. 2021 Jan 14;7(1):3; (3) Rudin CM. Nat Rev Dis Primers. 2021 Jan 14;7(1):3; (4) Petrelli F, et al. Mol Clin Oncol. 2021;15(4):218; (5) Liu LN, et al. Poster presented at: European Lung Cancer Congress; March 2024; Prague, Czech Republic. ZL-1310: Novel Delta-Like Ligand 3 (DLL3) Targeting ADC 5

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• Phase I, open-label, dose-escalation and expansion study of ZL-1310 as monotherapy and in combination with atezolizumab for r/r metastatic SCLC • We report data updated ZL-1310 monotherapy data with additional patients and follow-up from the ongoing Phase I trial Study Design of the Ongoing Phase 1 Study in ES-SCLC (Monotherapy) 6

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0.8 mg/kg (N=4) 1.2 mg/kg (N=11) 1.6 mg/kg (N=35) 2.0 mg/kg (N=29) 2.4 mg/kg (N=7) 2.8 mg/kg (N=3) Total (N=89) Median age, years (range) 67.0 (59, 69) 68.0 (55, 80) 65.0 (36, 77) 63.0 (52, 77) 66.0 (59, 79) 60.0 (58, 73) 65.0 (36, 80) Sex, n (%) Male 2 (50%) 5 (45%) 23 (66%) 19 (65%) 2 (29%) 1 (33%) 52 (58%) Female 2 (50%) 6 (55%) 12 (34%) 10 (35%) 5 (71%) 2 (67%) 37 (42%) Race, n (%) Asian 1 (25%) 0 13 (37%) 9 (31%) 2 (29%) 3 (100%) 28 (32%) White 3 (75%) 9 (82%) 21 (60%) 20 (69%) 5 (71%) 0 58 (65%) ECOG, n (%) 0 1 (25%) 2 (18%) 15 (43%) 9 (31%) 2 (29%) 0 29 (33%) 1 3 (75%) 9 (82%) 20 (57%) 20 (69%) 5 (71%) 3 (100%) 60 (67%) Brain metastasis, n (%)* Yes 2 (50%) 4 (36%) 8 (23%) 9 (31%) 2 (29%) 2 (67%) 27 (30%) No. of prior therapy line, n (%) 1 2 (50%) 7 (64%) 16 (46%) 11 (38%) 4 (57%) 2 (67%) 42 (47%) 2 2 (50%) 3 (27%) 11 (31%) 11 (38%) 1 (14%) 1 (33%) 29 (33%) ≥3 0 1 (9%) 8 (23%) 7 (24%) 2 (29%) 0 18 (20%) With prior anti-PD-(L)1 therapy, n (%) 4 (100%) 10 (91%) 31 (89%) 25 (86%) 7 (100%) 3 (100% ) 80 (90%) With prior topotecan/irinotecan, n (%) 0 2 (18%) 7 (20%) 9 (31%) 1 (14%) 1 (33%) 20 (23%) With prior lurbinectedin, n (%) 1 (25%) 2 (18%) 4 (11%) 5 (17%) 0 0 12 (14%) With prior DLL3 bi-specific Ab, n (%) 0 2 (18%) 4 (11%) 3 (10%) 1 (14%) 0 10 (11%) As of 1 Apr 2025, 89 pts were enrolled across 6 dose cohorts: - 47% pts received 1 prior line of therapy, 53% pts received 2 or more - 1.6, 2.0 and 2.4 mg/kg arms included 23%, 24% and 29% pts, respectively, had 3 or more prior lines - 90% pts received prior anti-PD- (L)1 therapy - 30% pts presented with brain metastasis at baseline, of which 8 were untreated Note: *Patients with brain metastases listed as target or non-target lesion, includes both previously treated and untreated lesions. Baseline and Disease Characteristics Baseline & Disease Characteristics 7

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Safety 8 TEAE, n (%) <2.0mg/kg (N=50) ≥2.0mg/kg (N=39) Total (N=89) Any TEAE 42 (84%) 37 (95%) 79 (89%) Grade ≥3 9 (18%) 17 (44%) 26 (29%) Leading to Dose Interruption 8 (16%) 17 (44%) 25 (28%) Leading to Dose Reduction 2 (4%) 4 (10%) 6 (7%) Leading to Drug Discontinuation 0 5 (13%) 5 (6%) Leading to Death 0 2 (5%) 2 (2%) Serious TEAE 11 (22%) 8 (21%) 19 (21%) TEAEs Related to ZL-1310 29 (58%) 36 (92%) 63 (73%) Grade ≥3 3 (6%) 17 (44%) 20 (23%) Leading to Dose Interruption 3 (6%) 14 (36%) 17 (19%) Leading to Dose Reduction 2 (4%) 4 (10%) 6 (7%) Leading to Drug Discontinuation 0 5 (13%) 5 (6%) Leading to Death 0 1 (3%) 1 (1%) Serious TEAE Related to ZL-1310 2 (4%) 5 (13%) 7 (8%) Safety Summary • As of 1 Apr 2025, 89 pts received at least one dose of ZL-1310 and included in the safety analysis • ZL-1310 demonstrated a well-tolerated safety profile • In doses < 2.0mg/kg: - Grade ≥3 TRAEs of 6% (3) - Serious TRAEs of 4% (2) - No TRAEs leading to drug discontinuation or death

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• Grade ≥3 hematologic toxicity was - Minimal in the low-dose group (4% neutropenia) - Manageable even at the higher dose levels (26% neutropenia) • In doses < 2.0mg/kg: - No Grade ≥3 ILD - 2 patients with ILD were Grade 1 and have been resolved and resumed ZL-1310 treatment TRAEs in ≥ 10% of the Patients n (%) <2.0mg/<kg (N=50) ≥2.0mg/kg (N=39) Total (N=89) All Grade Grade ≥3 All Grade Grade ≥3 All Grade Grade ≥3 Any TRAE 29 (58%) 3 (6%) 36 (92%) 17 (44%) 65 (73%) 20 (23%) Anemia 15 (30%) 1 (2%) 21 (54%) 9 (23%) 36 (40%) 10 (11%) Neutropenia* 7 (14%) 2 (4%) 20 (51%) 10 (26%) 27 (30%) 12 (14%) Nausea 10 (20%) 0 13 (33%) 0 23 (26%) 0 Leukopenia* 4 (8%) 0 16 (41%) 3 (8%) 20 (23%) 3 (3%) Thrombocytopenia* 2 (4%) 0 13 (33%) 4 (10%) 15 (17%) 4 (5%) Decreased appetite 8 (16%) 0 5 (13%) 0 13 (15%) 0 Fatigue 4 (8%) 0 6 (15%) 1 (3%) 10 (11%) 1 (1%) Lymphopenia* 3 (6%) 0 6 (15%) 2 (5%) 9 (10%) 2 (2%) Pneumonitis/ ILD 2 (4%) 0 7 (18%) 2 (5%) 9 (10%) 2 (2%) Note: *Neutropenia includes neutrophil decrease; Leukopenia includes white blood cell count decrease; Thrombocytopenia includes platelet count decrease; Lymphopenia includes lymphocyte count decrease. Safety (Cont’d) 9

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Efficacy – Dose Escalation Cohort 10 • For the 28 pts in dose escalation: - Confirmed ORR of 68% - mDOR not yet reached • Of the 19 responders in dose escalation: - 10 remain in response between 2.8 and 9.1 months from initial response - Half of ongoing responders are in response at approximately 6 months or above 0.8 mg/kg (N=4) 1.6 mg/kg (N=8) 2.0 mg/kg (N=6) 2.4 mg/kg (N=7) 2.8 mg/kg (N=3) Total (N=28) Best Overall Response – n (%) CR* 0 0 0 1 (14%) 0 1 (4%) PR* 3 (75%) 5 (63%) 4 (67%) 3 (43%) 3 (100%) 18 (64%) Stable Disease 0 3 (38%) 2 (33%) 2 (29%) 0 7 (25%) Progressive Disease 1 (25%) 0 0 1 (14%) 0 2 (7%) ORR* – n (%) 3 (75%) 5 (63%) 4 (67%) 4 (57%) 3 (100%) 19 (68%) Disease Control Rate – n (%) 3 (75%) 8 (100%) 6 (100%) 6 (86%) 3 (100%) 26 (93%) Best Overall Response in Dose Escalation (N=28) Notes: *All the responses are confirmed for 28 patients in the dose escalation cohort. As of data cut-off: Median follow-up time was 6.9 months (95% CI 2.4, 12.2)

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Efficacy by Lines of Therapy 11 Best Overall Response Across Lines of Therapy in All Patients (Dose Escalation and Dose Expansion, N=74) • 74 pts have had the opportunity to be followed to at least 1 post baseline tumor assessment • In 2L SCLC: - ORR* of 67% - DCR of 97% • Across all lines of therapy: - Of the 38 responders, 29 remain on study - Response rates declined in later lines of therapy - 27 of 31 pts (87%) with stable disease remain on study 2nd Line (N = 33) 3rd Line (N=26) > 3rd Line (N=15) All (N=74) Best Overall Response – n (%) CR1 2 (6%) 0 0 2 (2%) PR2 20 (61%) 11 (42%) 5 (34%) 36 (49%) Stable Disease 10 (30%) 13 (50%) 8 (53%) 31 (42%) Progressive Disease 1 (3%) 2 (8%) 2 (13%) 5 (7%) ORR – n (%) 22 (67%) 11 (42%) 5 (33%) 38 (51%) Confirmed 16 (49%) 7 (27%) 4 (27%) 27 (37%) Pending confirmation3 6 (18%) 4 (15%) 1 (6%) 11 (14%) Disease Control Rate – n (%) 32 (97%) 24 (92%) 13 (87%) 69 (93%) Notes: *Includes confirmed and unconfirmed responses. (1) Included 1 patient with confirmed CR and 1 patient with unconfirmed CR in patients with 1 prior line; (2) Included 15 patients with confirmed PR and 5 patients with unconfirmed PR in patients with 1 prior line; 7 patients with confirmed PR and 4 patients with unconfirmed PR in patients with 2 prior lines; 4 patients with confirmed PR and 1 patient with unconfirmed PR in patients with 3+ prior lines; (3) As the study is still ongoing, these responses are pending confirmation at the time of next tumor scan. As of data cut-off: Median treatment exposure was 2.8 months (95% CI 2.5, 3.4); Median follow-up time was 3.4 months (95% CI 2.8, 3.7)

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Efficacy by Dose Levels in Patients with 1 Prior Line 12 0.8 mg/kg (N=2) 1.6 mg/kg (N=14) ≥2.0 mg/kg (N=17) Total (N=33) Best Overall Response – n (%) CR1 0 0 2 (12%) 2 (6%) PR2 2 (100%) 11 (79%) 7 (41%) 20 (61%) Stable Disease 0 3 (21%) 7 (41%) 10 (30%) Progressive Disease 0 0 1 (6%) 1 (3%) ORR – n(%) 2 (100%) 11 (79%) 9 (53%) 22 (67%) Confirmed 2 (100%) 8 (57%) 6 (35%) 16 (49%) Pending confirmation3 0 (0%) 3 (22%) 3 (18%) 6 (18%) Disease Control Rate – n (%) 2 (100%) 14 (100%) 16 (94%) 32 (97%) • 1.6 mg/kg in 2L SCLC: - ORR* of 79% - DCR of 100% • All doses in 2L SCLC: - ORR* of 67% - DCR of 97% Best Overall Response in Patients with 1 Prior Line (N=33) Notes: *Includes confirmed and unconfirmed responses. (1) Included 1 patient with unconfirmed CR in 2.0 mg/kg cohort and 1 patient with confirmed CR in 2.4 mg/kg cohort; (2) Included 2 patients with confirmed PR in 0.8 mg/kg cohort; 8 patients with confirmed PR and 3 patients with unconfirmed PR in 1.6 mg/kg cohort; 3 patients with confirmed PR and 2 patients with unconfirmed PR in 2.0 mg/kg cohort; and 2 patients with confirmed PR in 2.8 mg/kg cohort; (3) As the study is still ongoing, these responses are pending confirmation at the time of next tumor scan. As of data cut-off: Median follow-up time was 3.7 months (95% CI <1, 12.2)

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Efficacy - Waterfall Plot 13 70 60 50 40 30 20 10 0 -10 -20 -30 -40 -50 -60 -70 -80 -90 -100 -110 -120 Best Percentage Change from Baseline in the Sum of the Diameters of Target Lesion (%) Waterfall Plot of Best Change in Sum of Target Lesions by Dose Levels (N=74) • Most pts had a decrease in target tumor lesion (89%) • 55% (17/31) of stable disease patients have tumor reduction and treatment is still ongoing • Longest patients remaining on study at 48+ weeks

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Efficacy - Spider Plot Spider Plot of Sum of Target Lesions over Time by Dose Levels (N=74) Percentage Change from Baseline in the Sum of the Diameters of Target Lesion % 50 40 30 20 10 0 -10 -20 -30 -40 -50 -60 -70 -80 -90 -100 0 6 12 18 24 30 36 42 48 54 60 Weeks After Treatment Initiation • Large reduction in target lesions seen in majority of patients across doses and lines of therapy • Majority of patients had tumor reduction by 6 weeks with median time to response of 5.57 weeks 14

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Efficacy - Spider Plot (Patients with 1 Prior Line) 15 Spider Plot of Sum of Target Lesions for 1 Prior Line (N=33) Percentage Change from Baseline in the Sum of the Diameters of Target Lesion % 0 6 12 18 24 30 36 42 48 54 60 50 40 30 20 10 0 -10 -20 -30 -40 -50 -60 -70 -80 -90 -100 Weeks After Treatment Initiation • In 2L SCLC: - 64% of patients with 1 prior line remain on study - Longest patient in response has been on study approaching 48 weeks - Longest patient at 1.6 mg/kg in response has been on study for over 36 weeks

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Efficacy – Patients with Brain Metastases Best Overall Response for Patients with Brain Metastases at Study Entry (N=22) • Pts with brain metastases at baseline (N=22) had an ORR* of 68% • Pts with brain metastases without prior radiation had an ORR* of 86% • 100% (4/4) pts with brain lesions who either had no prior radiation or received radiation more than 6 months earlier experienced intracranial tumor shrinkage All Pts w/ Brain Mets (N=22) Pts w/o prior radiation (N=7) Pts w/ prior radiation (N=15) Best Overall Response – n (%) CR1 1 (5%) 0 1 (7%) PR2 14 (64%) 6 (86%) 8 (53%) Stable Disease 5 (23%) 0 5 (33%) Progressive Disease 2 (9%) 1 (14%) 1 (7%) ORR – n (%) 15 (68%) 6 (86%) 9 (60%) Confirmed 10 (46%) 5 (71%) 5 (33%) Pending confirmation3 5 (22%) 1 (15%) 4 (27%) Notes: *Includes confirmed and unconfirmed responses. (1) Unconfirmed CR; (2) Included 10 patients with confirmed PR and 4 patients with unconfirmed PR in all patients with brain metastases; among patients without prior radiation, 5 patients with confirmed PR and 1 patient with unconfirmed PR; among patients with prior radiation, 5 patients with confirmed PR and 3 patients with unconfirmed PR; (3) As the study is still ongoing, these responses are pending confirmation at the time of next tumor scan. 16

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Conclusions Zai Lab Confidential. All Rights Reserved. • ZL-1310 demonstrated an acceptable safety profile with low rates of drug withdrawal and low-rates of high- grade adverse events • ZL-1310 presented encouraging anti-tumor activity in patients with relapsed or recurrent ES-SCLC, including those with brain metastases • Insufficient follow-up precludes computation of mDOR, but most patients with stable disease had tumor regression and 55% (17/31) of stable disease patients have tumor reduction and treatment is still ongoing • Responses were especially notable among patients who had undergone one line of prior platinum-based systemic therapy at the 1.6 mg/kg dose • Based on the Phase 1 trial data, a Phase 3 pivotal trial assessing ZL-1310 in ES-SCLC patients who have progressed during or after platinum-based therapy is planned to start later this year 17

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ZL-1310 (DLL3 ADC) Highlights from ASCO 2025 Next Steps and Conclusions Q&A with Dr. Amado and Dr. Spira 18 Rafael Amado, MD President, Head of Global Research and Development, Zai Lab

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ZL-1310 (Randomized study dose) Investigator’s choice of therapy R 1:1 Eligible Patients • ES-SCLC • Must have progressed following the platinum-based regimen • Received only 1 line of prior systemic therapy • At least one measurable lesion • ECOG 0-1 Stratification factors • Brain mets : Yes vs No • CTFI ≥90 days: Yes vs No • Investigator’s choice: Topo vs Lurb / Amru Primary endpoints • BICR-ORR • OS Secondary endpoints • DOR • PFS, TTR • Safety • QoL 2L ES-SCLC Development Strategy 19 Abbreviations: Chemotherapy free-interval (CTFI), topotecan (Topo), lurbinectedin (lurb), amrubicin (amru), quality of life (QoL). • Dose Optimization in 2L+ SCLC continuing with 1.2 mg/kg and 1.6 mg/kg • Randomized, registrational trial initiating in 2H’25 - Primary endpoint: OS, ORR (for accelerated approval)

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Rapidly Advancing ZL-1310 in SCLC and Other DLL3-Expressing Tumors 20 Combo1 Dose Escalation Combo1 Dose Optimization Combo Pivotal Study US BLA submission (AA) US BLA approval (AA) Enrolling Enrolling Follow up Notes: The estimate of development timeline is subject to FDA feedback. (1) Including doublet and triplet; decision will be based on the available data. 20272025 2026 2028+ 2L+ SCLC  Initiation of pivotal study in 2H’25 1L SCLC  Data update for ZL-1310 combo by YE’25 Other DLL3-expressing tumors  Ph1/2 study ongoing Key Catalysts 1L SCLC 2L+ SCLC Other Solid tumors Phase 1/2 Potentially Registrational Study Mono dose Optimization Mono Pivotal Study Enrolling

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ZL-1310 – Potential First-in-Class and Best-in-Class DLL3 ADC • 2L+ SCLC – High confirmed ORR of 68% across all doses in dose escalation (n=28) • 2L SCLC – Confirmed and unconfirmed ORR of 67% across all doses (n=33), with 1.6 mg/kg (n=14) demonstrating strongest response rate thus far with ORR of 79% • Potential best-in-class safety profile in doses <2.0 mg/kg (n=50), with Grade ≥3 TRAEs of 6%, no Grade ≥3 ILD and no TRAEs leading to drug discontinuation or death • Compelling intracranial activity for patients with brain metastases of 68% ORR (n=22); 86% ORR (n=6) in patients with brain metastases without prior radiation • ZL-1310’s safety and efficacy profile remains highly competitive in 2L SCLC, and advancing into 1L ES- SCLC as combination therapy • Other NECs – Global Phase 1/2 study ongoing Next Steps: Randomized, pivotal trial in 2L SCLC to initiate in H2 2025 with 1.6 mg/kg* Note: * Pending FDA agreement.

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ZL-1310 (DLL3 ADC) Highlights from ASCO 2025 Next Steps and Conclusions Q&A with Dr. Amado and Dr. Spira 22 Rafael Amado, MD President, Head of Global Research and Development, Zai Lab Alex Spira, MD, PhD, FACP, FASCO Co-Director, Virginia Cancer Specialists Research Institute

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