Zai Lab presents updated data from Phase 1a/1b trial evaluating ZL-1310

Zai Lab (ZLAB) announced that updated data from an ongoing, global Phase 1a/1b clinical trial evaluating zocilurtatug pelitecan, or ZL-1310, the Company’s potential first-in-class, Delta-like ligand antibody-drug conjugate for patients with extensive-stage small cell lung cancer, ES-SCLC, will be presented today during a poster session at the 2025 American Society of Clinical Oncology, ASCO, Annual Meeting. Key efficacy results include: Across all dose levels in the 2L treatment setting, the unconfirmed objective response rate in patients was 67% and the disease control rate was 97%. The most promising combination of response and tolerability was observed in the 1.6 mg/kg arm with a uORR of 79% and a DCR of 100%. Across all doses and lines of therapy, of 38 patients with confirmed and unconfirmed ORR, 29 remain on study, with the longest responder surpassing nine months of treatment. Eighty-nine percent of patients experienced a reduction in their tumor burden. Response rates declined with increased prior treatment burden and higher dose levels, consistent with more advanced disease and potential tolerability limitations above 2.0 mg/kg. Of the 22 response-evaluable patients with baseline brain metastases, a 68% ORR was observed. In patients without prior cranial irradiation, ORR was 86%. Responses were seen in patients following treatment with a prior DLL3 bi-specific across lines of therapy. Median length of follow-up is immature at 3.4 months, making median duration of response not estimable.