A Phase II Study of QL1706 With Anti-angiogenesis Therapy and Chemotherapy in Extensive-stage Small Cell Lung Cancer.

This single-arm, open-label, Phase II study assesses first-line QL1706 + bevacizumab (anti-VEGF) + platinum/etoposide chemotherapy to treat naïve ES-SCLC patients.The main questions it aims to answer are: Evaluate efficacy and safety of this quadruplet regimen in ES-SCLC Explore correlations between tumor biomarkers and treatment efficacy Participants will: Histologically or cytologically confirmed, treatment-naïve extensive-stage small cell lung cancer (ES-SCLC). Willing to provide archived or fresh tumor tissue samples. If unavailable, enrollment may proceed per investigator assessment. At least one measurable lesion per RECIST v1.1

Small cell lung cancer (SCLC) is a highly aggressive malignancy, accounting for 13-15% of all lung cancers. Approximately two-thirds of patients present with distant metastases at diagnosis, defined as extensive-stage SCLC (ES-SCLC). Prognosis remains poor, with median overall survival (mOS) of 12-15 months despite standard first-line chemotherapy using etoposide plus cisplatin/carboplatin (EP/EC), which offers limited benefit (mOS \~10 months; median progression-free survival \[mPFS\] \~5 months). Immune checkpoint inhibitors (ICIs) have improved outcomes modestly. IMpower133, KEYNOTE-604, RATIONALE-312, and EXTENTORCH trials confirmed the benefit of adding PD-1/PD-L1 inhibitors to chemotherapy, but the survival plateau remains. Dual immune checkpoint blockade strategies, including PD-1/PD-L1 with CTLA-4 inhibitors, have not significantly improved outcomes and pose higher toxicity, as seen in CASPIAN and CheckMate451 studies. Antiangiogenic therapy offers another promising direction. Studies such as SALUTE, ACTION-2, and BEAT-SC have explored bevacizumab or anlotinib combined with chemo-immunotherapy, showing potential survival gains. Notably, the ETER701 study using a four-drug combination achieved mOS of 19.3 months, although with increased adverse events. QL1706 (Aito combination antibody) is a novel bifunctional antibody targeting PD-1 and CTLA-4 in a 2:1 fixed ratio, designed to optimize synergy while reducing CTLA-4 toxicity. Approved in 2024, it has demonstrated efficacy and tolerability in multiple solid tumors. In NSCLC, QL1706 combined with chemotherapy and antiangiogenic therapy showed mPFS up to 8.5 months and mOS of 26.5 months. To date, no clinical data exist for QL1706 combined with antiangiogenic therapy and chemotherapy in ES-SCLC. A phase II, open-label, single-arm clinical trial is proposed to evaluate its efficacy and safety as first-line treatment. This study aims to explore a new therapeutic strategy to overcome the current survival limitations in ES-SCLC.