Efficacy of atezolizumab in combination with carboplatin and etoposide in first-line therapy for advanced small cell lung cancer in real clinical practice: a retrospective single-center study

Objective. To evaluate the efficacy and safety of atezolizumab in combination with carboplatin and etoposide in the first-line treatment of advanced small cell lung cancer (SCLC) in real-life clinical practice. Material and methods. A retrospective single-center cohort study was conducted. The analysis included 58 consecutive patients with advanced SCLC who received atezolizumab plus carboplatin and etoposide in the first-line treatment from SEP/2020 to SEP/2025 at the Irkutsk Regional Oncology Dispensary. Database slice completed as of 04/MAR/2026. The primary endpoints were overall survival (OS) and progression-free survival (PFS); secondary endpoints were objective response rate (ORR), disease control (DCR), completion of the induction phase of therapy, and safety profile. Survival analysis was performed using Kaplan-Meier method. Results. The median age of patients was 63.3 years; 20.7% of patients had ECOG 2, and brain metastases were detected in 13.8% of patients. The ORR was 58.6%, including 3.4% complete responses; DCR reached 82.8%. Median PFS was 7.2 months, median OS was 11.2 months. 75.9% of patients completed the induction stage of 4–6 cycles of therapy, after which they were switched to atezolizumab maintenance therapy. Adverse events or clinically significant laboratory abnormalities were reported in 72.4% of patients and the most common were hematologic complications, including anemia (43.1%) and leukopenia (22.4%). Immune-mediated complications were rare; a single case of myocarditis has been reported. Conclusion. Atezolizumab in combination with carboplatin and etoposide demonstrated clinically significant anti-tumor activity and acceptable tolerability in patients with advanced SCLC in a real-world setting. These results confirm the reproducibility of key effects of the IMpower133 pivotal study in a less selective population and support the use of this regimen as a first-line standard of care.