Financial Data and Key Metrics Changes - The company reported a confirmed overall response rate (ORR) of 68% and a disease control rate of 93% across all dose levels in the ongoing clinical trial for ZL1310 [12][21] - The median follow-up for the efficacy evaluable patients was 3.4 months, with some patients remaining in response for over 9 months [22][43] Business Line Data and Key Metrics Changes - ZL1310, the investigational DLL3 targeted antibody-drug conjugate, demonstrated promising clinical activity in patients with relapsed or refractory extensive stage small cell lung cancer [6][19] - The safety profile of ZL1310 was reported as manageable, with only 16% of patients in the low-dose group requiring dose interruptions [10][19] Market Data and Key Metrics Changes - Small cell lung cancer accounts for approximately 15% of all lung cancers, affecting around 372,000 patients worldwide, with a poor prognosis and a median overall survival of about 13 months [6][19] - The estimated global prevalence of DLL3 expressing neuroendocrine carcinomas is roughly 350,000 to 400,000 patients, indicating a significant market opportunity for ZL1310 [26] Company Strategy and Development Direction - The company plans to initiate a registrational study in second-line small cell lung cancer later this year, with overall survival as the primary endpoint [22][23] - There is a strategy to expand ZL1310 into first-line small cell lung cancer and other DLL3 expressing solid tumors, aiming to reduce treatment burden for patients [25][26] Management's Comments on Operating Environment and Future Outlook - Management expressed confidence in the potential for accelerated approval based on the promising data and ongoing discussions with the FDA [56][57] - The company is optimistic about the efficacy of ZL1310 in the competitive landscape, particularly in comparison to existing therapies [48][49] Other Important Information - The company is exploring combination therapies with ZL1310, including carboplatin and atezolizumab, to enhance treatment efficacy [38][39] - The company has received fast track designation from the FDA, which may facilitate the development process [32] Q&A Session Summary Question: Can you comment on the therapeutic window and confidence in the selected dose for pivotal studies? - Management indicated that the 1.6 mg/kg dose shows a good balance of efficacy and safety, with a slight attrition in response at higher doses [29][30] Question: What is the dosing strategy and safety consideration for the combination trial? - The company is methodically exploring combinations with existing chemotherapy regimens and is confident in the competitive activity of ZL1310 [37][38] Question: How does the durability of ZL1310 compare to competitors in refractory small cell lung cancer? - Management noted that the durability of response is clinically meaningful, with a median follow-up of 6.9 months for the most mature data set [42][43] Question: What gives confidence in potential accelerated approval for ZL1310? - Ongoing discussions with the FDA suggest that accelerated approval is a viable option, contingent on the results of the randomized trial [56][57] Question: What are the remaining items to align with the FDA before initiating the pivotal study? - The main focus is to finalize the dosing strategy and ensure alignment on study design with the FDA [65][66]

Summary of Zai Lab (ZLAB) Update / Briefing June 02, 2025 Company and Industry Overview - **Company**: Zai Lab (ZLAB) - **Industry**: Oncology, specifically focusing on small cell lung cancer (SCLC) and DLL3 targeted therapies Key Points and Arguments Clinical Data and Efficacy - **ZL1310**: Investigational DLL3 targeted antibody-drug conjugate (ADC) showing promising clinical activity in patients with recurrent SCLC [4][8] - **Patient Demographics**: 89 patients enrolled in the trial, with 47% having one prior line of therapy and 53% having failed at least two prior lines [10] - **Efficacy Results**: - Confirmed overall response rate (ORR) of 68% and disease control rate (DCR) of 93% across all dose levels [14] - In second-line patients, ORR remains robust at 67% with a DCR of 97% [15] - Notably, the 1.6 mg/kg dose arm achieved an unconfirmed ORR of 79% and a 100% DCR [16] - **Intracranial Activity**: 68% ORR in patients with brain metastases, with 86% response in those without prior cranial radiation [21] Safety Profile - **Safety Analysis**: ZL1310 demonstrated a well-tolerated safety profile, with only 16% of patients in the low-dose group requiring dose interruptions [12] - **Adverse Events**: Most common treatment-related adverse events included anemia (40%), neutropenia (30%), and nausea (26%) [13] - **High-Grade Adverse Events**: Only 6% experienced grade three or greater toxicity in the lower dose group [12] Future Development Plans - **Phase III Trial**: A registrational study in second-line SCLC is planned to start later this year, comparing ZL1310 against investigator's choice of therapy [24][25] - **Combination Studies**: Exploring combinations with checkpoint inhibitors and chemotherapy, aiming to demonstrate competitive efficacy [40] - **Expansion into Other Tumors**: Plans to pursue opportunities in first-line SCLC and neuroendocrine carcinoma, targeting DLL3 expressing tumors [27] Regulatory Considerations - **Accelerated Approval**: Discussions with the FDA indicate potential for accelerated approval based on response rates in the randomized trial [58] - **Study Design**: The pivotal study will include patients with extensive stage SCLC who have progressed after first-line platinum-based therapy [25][66] Additional Important Insights - **Therapeutic Window**: The 1.6 mg/kg dose shows a promising balance of efficacy and tolerability, with ongoing discussions about dose optimization [33][34] - **Durability of Response**: Median follow-up for responders is 6.9 months, with a significant number of patients remaining in response [44] - **Comparison with Competitors**: ZL1310 is positioned as a more easily administered outpatient option compared to other therapies like pirilatumab, which may have logistical challenges [52] This summary encapsulates the critical findings and future directions for Zai Lab's ZL1310 program, highlighting its potential impact on the treatment landscape for small cell lung cancer.