ZAI LAB (09688.HK): Zoci Plus Atezolizumab in First-Line ES-SCLC Yields 81.8% Confirmed ORR

NewTimeSpace News: On 23 October 2026, Zai Lab Limited (the "Company") announced, pursuant to Rule 13.09(2)(a) of the Listing Rules and the inside information provisions under Part XIVA of the Securities and Futures Ordinance (Chapter 571 of the Laws of Hong Kong), the first data from a global Phase 1b clinical study evaluating zocilurtatug pelitecan (zoci, formerly ZL-1310) in combination with atezolizumab (with or without carboplatin) for the first-line treatment of extensive-stage small cell lung cancer (ES-SCLC), which will be presented at the European Society for Medical Oncology (ESMO) 2026 Congress in Madrid, Spain. The announcement stated that the regimen demonstrated a high response rate, encouraging durability and a well-tolerated safety profile in first-line ES-SCLC.

The announcement disclosed that, at the recommended Phase 3 dose (RP3D) of 1.6 mg/kg, based on data as of the September 2026 data cut-off, among patients receiving zoci 1.6 mg/kg plus atezolizumab every three weeks (n=33), the investigator-assessed confirmed objective response rate (ORR) reached 81.8% (27/33; 95% CI: 64.5-93.0) and the six-month progression-free survival (PFS) rate was 81.9% (n=33). Among patients treated with zoci 1.6 mg/kg plus atezolizumab with at least six months of follow-up (n=15), after a median follow-up of 10 months, median PFS (mPFS) and median duration of response (mDOR) had not yet been reached; at the data cut-off, 10 of these 15 patients (66.7%) remained free of disease progression or death.

The Company stated that no dose-limiting toxicities were observed during dose escalation of the doublet; at the 1.6 mg/kg dose, the common (>=20%) zoci-related treatment-emergent adverse events (TEAEs) of any grade were anaemia (48.5%), nausea (36.4%), leukopenia (30.3%), decreased appetite, increased ALT and neutropenia (27.3% each) and lymphopenia (21.2%), most of which were grade 1 or 2 and non-serious; zoci-related grade 3 or higher adverse events occurred in 3/33 patients (9.1%), with no treatment-related discontinuations and only one grade 1 case of interstitial lung disease/non-infectious pneumonitis. An indirect comparison showed that zoci plus atezolizumab has a favourable safety profile relative to chemotherapy plus immuno-oncology (IO) regimens. In addition, patients who received the triplet of zoci plus atezolizumab and carboplatin as first-line treatment (n=13; three dose levels) showed a high ORR of 92.3%, with median PFS across all dose levels of 8.4 months (95% CI: 3.7 to not reached) and median DOR of 7.7 months.

The Company stated that a global randomised Phase 3 study in first-line ES-SCLC is expected to be initiated before the end of 2026. Zoci is an antibody-drug conjugate (ADC) targeting delta-like ligand 3 (DLL3), which is overexpressed in small cell lung cancer, and has the potential to become the Company's first globally marketed oncology product. In addition to the Phase 3 combination study being prepared, the Company is conducting the Phase 3 DLLEVATE study evaluating zoci against physician's choice of chemotherapy in previously treated ES-SCLC, and a Phase 1/2 study in neuroendocrine carcinoma (NEC) and other DLL3-positive solid tumours. The Company has also entered into a global clinical research collaboration with Amgen to evaluate zoci in combination with IMDELLTRA (tarlatamab), a DLL3/CD3 bispecific T-cell engager, in ES-SCLC, and a clinical research collaboration with Boehringer Ingelheim to evaluate zoci in combination with obrixtamig in small cell lung cancer and other neuroendocrine carcinomas.