On Friday, Zai Lab Ltd (ZLAB.US) saw its shares climb nearly 10% at the market open before settling to a gain of more than 2%, trading at $22.62.

On October 23, Zai Lab Ltd released global Phase Ib clinical trial data for its investigational antibody-drug conjugate (ADC) Zocilurtatug Pelitecan (referred to as "Zoci," formerly known as ZL-1310) in first-line extensive-stage small cell lung cancer. The results are scheduled to be presented on October 26 at the 2026 European Society for Medical Oncology (ESMO) Congress.

The data showed that at the recommended Phase III dose of 1.6 mg/kg, Zoci combined with atezolizumab in 33 patients achieved a confirmed objective response rate (ORR) of 81.8%, with an estimated 6-month progression-free survival rate of 81.9%. Among 15 patients followed for at least 6 months, after a median follow-up of 10 months, both median progression-free survival and median duration of response had not yet been reached, indicating that most patients continue to benefit from the treatment.

In terms of safety, among the 33 patients who received the dual-agent regimen, the incidence of Grade 3 or higher adverse events related to Zoci was 9.1%. Additionally, the triple combination of Zoci plus atezolizumab and carboplatin achieved an objective response rate of 92.3% in 13 patients treated at various doses, with a median progression-free survival of 8.4 months and a median duration of response of 7.7 months. However, the incidence of Grade 3 or higher treatment-emergent adverse events for the triple regimen reached 76.9%, higher than the 21.2% observed with the dual-agent regimen.

Currently, the first-line standard of care for extensive-stage small cell lung cancer is immune checkpoint inhibitors combined with chemotherapy. Zai Lab Ltd stated that these findings support further exploration of ADC plus immunotherapy as a replacement for traditional platinum-based chemotherapy regimens. The company plans to initiate a global randomized Phase III clinical trial before the end of 2026 to evaluate the efficacy and safety of Zoci combined with immunotherapy for first-line treatment of extensive-stage small cell lung cancer.