The Real-World Outcome of First Line Atezolizumab in Extensive-Stage Small Cell Lung Cancer: A Multicenter Prospective Cohort Study

Purpose The addition of immune checkpoint inhibitors to chemotherapy has improved survival outcomes in patients with extensive-stage small cell lung cancer (ES-SCLC). However, their real-world effectiveness remains unknown. Therefore, we investigated the effectiveness of atezolizumab plus chemotherapy in ES-SCLC in actual clinical settings.Materials and Methods In this multicenter prospective cohort study, patients with ES-SCLC receiving or scheduled to receive atezolizumab in combination with etoposide and carboplatin were enrolled between June 2021 and August 2022. The primary outcomes were progression-free survival (PFS) and the 1-year overall survival (OS) rate.Results A total of 100 patients with ES-SCLC were enrolled from seven centers. Median age was 69 years, and 6% had an Eastern Cooperative Oncology Group performance status (ECOG PS) ≥ 2. The median PFS was 6.0 months, the 1-year OS rate was 62.2%, and the median OS was 13.5 months. An ECOG PS of 2-3 and progressive disease as the best response were poor prognostic factors for PFS, while an ECOG PS of 2-3 and brain metastasis were associated with poor prognosis for OS. In addition, consolidative thoracic radiotherapy was found to be an independent favorable prognostic factor for OS (hazard ratio, 0.336; p=0.021). Grade ≥ 3 treatment-related adverse events were observed in 7% of patients, with treatment-related deaths occurring in 2% of patients.Conclusion We provided evidence of the favorable real-world effectiveness and safety of atezolizumab plus chemotherapy in ES-SCLC patients, including in the elderly and those with poor ECOG PS. Additional consolidative thoracic radiotherapy may also benefit ES-SCLC patients.