Zai Lab's Zocilurtatug Pelitecan (Zoci, Formerly ZL-1310) Demonstrates High Response Rates, Encouraging Durability and Well-Tolerated Safety Profile in First-Line Extensive-Stage Small Cell Lung Cancer

Zai Lab's zoci, an antibody-drug conjugate (ADC), combined with the immuno-oncology agent atezolizumab, demonstrated promising early results in a Phase 1b trial for first-line extensive-stage small cell lung cancer. At the recommended Phase 3 dose, the combination reportedly achieved an 81.8% confirmed objective response rate among 33 patients, with an estimated 81.9% six-month progression-free survival rate.

These findings suggest a potential improvement over the current standard of care, which typically involves a checkpoint inhibitor plus chemotherapy. That regimen is cited as delivering a 60-70% response rate and a median progression-free survival of approximately five months, with Grade > 3 treatment-related adverse events in about 60% of patients.

In contrast, the zoci and atezolizumab combination was reported to be well-tolerated, with Grade > 3 adverse events related to zoci occurring in 9.1% of patients. The trial also indicated encouraging durability, as median progression-free survival and median duration of response were not yet reached after a median follow-up of 10 months among 15 patients with at least six months of follow-up.

This platinum-free approach could allow for longer treatment durations compared to chemotherapy and potentially offer a better tolerability profile, which Zai Lab believes positions zoci as a potential ADC backbone in this cancer type. While these early results from a Phase 1b trial are encouraging, they are based on a relatively small patient cohort and require validation in larger, randomized Phase 3 studies.