Efficacy and safety of envafolimab plus carboplatin and etoposide as first-line treatment for extensive-stage small-cell lung cancer: A prospective, single-arm, phase II trial.

8090 Background: Extensive-stage small cell lung cancer (ES-SCLC) is related to high malignancy and the poor prognosis. At present, immunotherapy combined with chemotherapy resulted in favorable therapeutic efficacy, and had been established as the standard treatment regimen for first-line treatment of ES-SCLC. However, some patients may still experience intolerable AEs over the course of treatment, such as immune-related pneumonitis and enteritis. Additionally, currently marketed ICIs were administered by continuous intravenous infusion, which is inconvenient for patients. This trial aimed to evaluate the efficacy and safety of envafolimab, which is a subcutaneously administered fusion protein of humanized anti-PD-L1 monodomain antibody, plus chemotherapy as a first-line treatment for ES-SCLC. Methods: This prospective, single-arm, phase II trial was conducted at the Fifth Medical Center of Chinese PLA General Hospital. Eligible patients with histologically or cytologically confirmed ES-SCLC were consecutively enrolled. Patients were given four cycles of carboplatin (5-6 mg/mL/min, day 1 of each cycle) and etoposide (80-100 mg/m², days 1-3 of each cycle) with envafolimab (300 mg, Q3W, day 3 post-chemotherapy of each cycle), followed by envafolimab maintenance until disease progression or intolerable toxicity. The primary endpoint was progression-free survival (PFS), and the secondary endpoint included objective response rate (ORR), disease control rate (DCR), and safety. Results: Between October 2021 and November 2022, a total of 32 patients were enrolled in this study. 32 patients were included for safety analysis, and 31 patients were included for efficacy analysis. As of the data cutoff (September 15, 2024), the median follow-up was 27.7 months. The ORR was 87.1% (95% CI, 70.2-96.4%), and the DCR was 100% (95% CI, 88.8-100%). The median DoR was 5.47 months (95% CI, 3.43-10 months). The median PFS was 6.43 months (95% CI, 4.83-7.67 months), and median OS was 20 months (95% CI, 14.7-NA). Treatment-related adverse events (TRAEs) of any grade were reported in 59.4% of patients, with grade ≥ 3 TRAEs in 15.6% patients. No treatment-related deaths occurred. Conclusions: First-line envafolimab in combination with carboplatin and etoposide yielded favorable clinical efficacy with a manageable safety profile for patients with ES⁃SCLC, representing a promising treatment modality. Clinical trial information: ChiCTR2100044981 .