Zai Lab's DLL3 ADC Shows 68% Response Rate in Small Cell Lung Cancer, Advances to Global Registrational Study
核心洞察
Zocilurtatug pelitecan (搜索) demonstrated a 68% overall response rate at 1.6 mg/kg dose in second-line extensive-stage small cell lung cancer (搜索) patients.
The DLL3 (搜索)-targeted antibody-drug conjugate showed meaningful activity in brain metastases (搜索) with an 80% response rate in untreated cases.
Zai Lab initiated a global registrational study in second-line+ ES-SCLC based on the promising Phase 1 data presented in October 2025.
Zai Lab's investigational DLL3 (搜索)-targeted antibody-drug conjugate zocilurtatug pelitecan (搜索) has demonstrated significant clinical activity in extensive-stage small cell lung cancer (搜索), prompting the company to advance the therapy into a global registrational study for second-line and beyond treatment.
Promising Efficacy Data Supports Registrational Study
In October 2025, Zai Lab presented updated Phase 1 results at the AACR-NCI-EORTC International Conference, showing a best overall response rate of 68% at the 1.6 mg/kg dose in second-line extensive-stage small cell lung cancer (搜索). The estimated median duration of response of 6.1 months across all doses and all lines of therapy represents encouraging activity for a monotherapy in this heavily pre-treated and difficult-to-treat patient population.
The data revealed particularly notable activity in patients with brain metastases (搜索), including an 80% response rate in patients with untreated brain metastases. This finding addresses a critical unmet need, as brain metastases are common in small cell lung cancer and represent a significant clinical challenge.
Favorable Safety Profile Enables Dose Advancement
The safety profile at the 1.6 mg/kg dose proved well-tolerated, with Grade ≥3 treatment-related adverse events occurring in only 13% of patients. Importantly, the study reported no Grade ≥2 interstitial lung disease and no drug discontinuations, addressing key safety concerns that have affected other therapies in this class.
"Together, these results reinforce zoci's best-in-class potential and support the initiation of the global registrational study," according to the company's announcement. The favorable risk-benefit profile enabled Zai Lab to initiate the global registrational study of zocilurtatug pelitecan (搜索) monotherapy in second-line+ extensive-stage small cell lung cancer (搜索) in October 2025.
Expanding Development Program
Beyond the second-line setting, Zai Lab is advancing zocilurtatug pelitecan (搜索) across multiple indications. The company plans to provide data readout from a Phase 1 study evaluating combination therapy with atezolizumab and/or chemotherapy in first-line ES-SCLC in the first half of 2026, with plans to advance into a registrational study in 2026 based on emerging data.
The development program also includes exploration in other neuroendocrine carcinomas (搜索), with a global Phase 1/2 study in patients with selected solid tumors expected to provide data readout in the first half of 2026.
Strong Financial Performance Supports Pipeline Advancement
Zai Lab reported total revenues of $116.1 million in the third quarter of 2025, representing 14% year-over-year growth. The company's operating loss improved by 28% year-over-year to $48.8 million, and by 42% to $28.0 million on an adjusted basis. Based on this performance, Zai Lab revised its total revenue guidance for the full year 2025 to at least $460 million.
"With zoci moving into pivotal development less than two years after IND and multiple differentiated global programs progressing in parallel, we are demonstrating the speed, scientific rigor, and global ambition of our R&D engine," said Dr. Samantha Du, Founder, Chairperson, and CEO of Zai Lab.
Broader Pipeline Progress
The company is simultaneously advancing other high-potential global programs, including the initiation of a global Phase 1 study for ZL-1503, an IL-13xIL-31R bispecific antibody, and a planned IND submission for ZL-6201, an LRRC15 (搜索) ADC, by year-end 2025.
Zai Lab's cash position remains strong with $817.2 million in cash and cash equivalents, short-term investments, and current restricted cash as of September 30, 2025, providing financial flexibility to support its expanding pipeline and commercial operations.