Zai Lab Limited (NASDAQ: ZLAB; HKEX: 9688) has shared the first data on zocilurtatug pelitecan (zoci, formerly ZL-1310). The global Phase 1b trial tests zoci with atezolizumab, with and without carboplatin. Researchers are studying the regimen as a first-line treatment for extensive-stage small cell lung cancer (ES-SCLC). Zai Lab is an innovation-driven, global biopharma company. The company will present the results at the European Society for Medical Oncology (ESMO) Congress 2026 in Madrid, Spain.
At the recommended Phase 3 dose (RP3D) of 1.6 mg/kg, zoci plus atezolizumab produced a confirmed objective response rate (ORR) of 81.8% (27/33). Moreover, the estimated six-month progression-free survival (PFS) rate reached 81.9% (n=33). The Phase 1b data show that the doublet was well tolerated. Grade ≥3 adverse events (AEs) related to zoci occurred in 9.1% (3/33) of patients at 1.6 mg/kg.
Zai Lab also plans to start a global, randomized Phase 3 study in first-line ES-SCLC by year-end 2026. Meanwhile, the company will host an investor conference call and webcast today, October 23, at 8:00 a.m. ET / 8:00 p.m. HKT. The call will cover the ESMO 2026 data and the zoci clinical trial plans.
Rafael G. Amado, M.D., President, Head of Global Research and Development at Zai Lab, commented on the results.
“Despite advances in treatment, extensive-stage small-cell lung cancer remains a devastating disease, with many patients experiencing disease progression within approximately five months of initiating standard first-line treatment,” said Rafael G. Amado, M.D., President, Head of Global Research and Development at Zai Lab. “The high confirmed response rate, encouraging durability, and well-tolerated safety profile we are seeing with a standard chemotherapy-free regimen are particularly compelling. We believe zoci’s combination of efficacy and safety positions it to become an ADC backbone of choice in small-cell lung cancer, including in combination with immunotherapies. We are preparing to initiate a global Phase 3 trial of zoci and an Immuno-Oncology (IO) regimen and continue to evaluate the potential of combinations with T-cell engagers and IO.”
Zoci Plus Atezolizumab Doublet: Efficacy and Safety Details
The data cut-off for the ESMO presentation is September 2026. The analysis covers 33 patients who received zoci 1.6 mg/kg with atezolizumab every three weeks. Investigator assessment confirmed an ORR of 81.8% (95% CI: 64.5–93.0). In addition, the six-month PFS rate stood at 81.9%.
Fifteen patients were followed for at least 6 months on the 1.6 mg/kg dose. Their answers were quite resilient. Median progression-free survival (mPFS) was not reached at a median follow-up of 10 months. Thus, most patients will continue to benefit from treatment. At data cut-off, 10 of these 15 patients (66.7%) were progression-free or alive. Similarly, median duration of response (mDOR) has not yet been reached in this population.
The doublet also showed a favorable safety profile over a chemo plus IO regimen by indirect comparison. Notably, investigators observed no dose-limiting toxicities during dose escalation. The most common zoci-related treatment-emergent adverse events (TEAEs) of all grades (≥20%) at 1.6 mg/kg included:
- Anemia (48.5%)
- Nausea (36.4%)
- Leukopenia (30.3%)
- Decreased appetite, ALT increase and neutropenia (27.3% each)
- Lymphopenia (21.2%)
Most AEs were Grade 1 or 2 and non-serious. Grade ≥3 AEs related to zoci occurred in 3/33 (9.1%) patients. No patients discontinued treatment because of treatment-related AEs. Furthermore, the trial recorded only one Grade 1 interstitial lung disease (ILD)/pneumonitis case.
Triplet Regimen Results and the Current Standard of Care
The trial also tested zoci with atezolizumab and carboplatin as first-line therapy. Thirteen patients received this triplet across three dose levels. It included two dose levels of zoci and two dose levels of carboplatin. The triplet delivered a high ORR of 92.3%. Across all dose levels, mPFS reached 8.4 months (95% CI: 3.7-NA), and mDOR reached 7.7 months (2.6, NA).
However, the triplet carried a heavier safety burden than the doublet. Patients had more frequent Grade ≥3 TEAEs, including study-drug related hematological AEs. They also had a higher rate of dose interruptions. Grade ≥3 TEAEs reached 21.2% for the doublet at 1.6 mg/kg. By contrast, the rate was 76.9% for the triplet across all doses.
Today’s standard of care for first-line SCLC is a checkpoint inhibitor plus chemotherapy. This approach delivers a 60-70% response rate and an mPFS of about 5 months. Grade >3 treatment-related AEs occur in around 60% of patients. In contrast, a platinum-free regimen could offer better tolerability. Zoci combined with an IO or other novel agents could also allow longer treatment than the typical four to six cycles of platinum-based induction chemotherapy. Additionally, it could improve control of brain metastases.
Pedro Rocha, M.D., Ph.D., study investigator and medical oncologist at Vall d’Hebron University Hospital in Barcelona, Spain, also weighed in.
“The zoci and atezolizumab doublet demonstrated substantial early antitumor activity with high, durable responses and a favorable safety profile, which are very encouraging results for patients with extensive-stage small cell lung cancer,” said Pedro Rocha, M.D., Ph.D., study investigator and medical oncologist at Vall d’Hebron University Hospital in Barcelona, Spain. “Importantly, this platinum-free regimen may allow patients to stay on treatment longer with potentially fewer side effects. These results support further exploration of zoci in combination regimens. I look forward to seeing how this profile evolves as the clinical program advances.”
Based on the data from this trial, Zai Lab is preparing to initiate a global Phase 3 randomized study. The study will evaluate a zoci and IO regimen in first-line treatment of ES-SCLC.
Explore Health Tech Insiders for the latest medical innovations and reliable strategic insights driving the future of technology-driven healthcare transformation.
News Source: Businesswire.com
