Sintilimab combined with anlotinib and chemotherapy as second-line or later therapy in extensive-stage small cell lung cancer: a phase II clinical trial

Treatment options for patients with relapsed extensive-stage small cell lung cancer (ES-SCLC) remain scarce. This study aims to evaluate the efficacy and safety of combining anlotinib and sintilimab plus chemotherapy as a second line or later therapy for ES-SCLC patients. This is a phase II clinical trial (ChiCTR2100049390) conducting at Shandong Cancer Hospital. Patients with ES-SCLC and received at least one prior systemic treatment were enrolled. The trial design involved a combination therapy (sintilimab, anlotinib, and nab-paclitaxel) administered over six 21-day cycles, followed by maintenance sintilimab therapy. The primary endpoint was objective response rate (ORR). Circulating tumor DNA sequencing was employed for exploratory analysis. From July 2021 to April 2023, 25 eligible patients were enrolled. The confirmed ORR was 60% (95% CI: 38.7–78.9%) and the DCR was 76% (95% CI: 54.9–90.6%). The mPFS was 6.0 months (95% CI: 5.4–9.7), and the 6-month PFS rate was 49.2%. The mOS was 13.4 months (95% CI: 11.8-NR), with a 12-month survival rate of 62.2%. Treatment-related adverse events (TRAEs) of any grade occurred in 80% of patients, with the most common being fatigue (40%) and nausea (32%). TRAEs of Grade 3 or higher were reported in 12% of patients. ctDNA analysis indicated that low on-treatment blood tumor mutation burden was associated with longer PFS and OS and a potential role of KMT2D mutation in treatment resistance. This combination therapy shows promising efficacy and a manageable safety profile as a second-line or later treatment for ES-SCLC, with genomic insights providing potential biomarkers for treatment response.