Does using atezolizumab with more combination chemotherapy prolong survival in small cell lung cancer?

Aim: For nearly 50 years, the standard first-line treatment for small cell lung cancer (SCLC) has been platinum-based chemotherapy combined with etoposide regimen. The use of atezolizumab in combination with chemotherapy in the first-line treatment of extensive-stage SCLC has recently been shown to improve survival in a randomized trial. Patients with SCLC not treated with immunotherapy received standard 6 cycles of platinum-based chemotherapy with the most effective survival results, whereas in the randomized trial of atezolizumab, standard 4 cycles of chemotherapy were administered. This retrospective study aims to present real-life data of atezolizumab combined with 6 cycles of chemotherapy in the first-line treatment of extensive-stage SCLC. Material and Methods: The study included patients diagnosed with disseminated SCLC in our clinic who received a minimum of 6 cycles of treatment with carboplatin-etoposide plus atezolizumab in the first-line induction phase. Patients who completed the induction phase received atezolizumab 1200 mg every 3 weeks in the maintenance phase. Patients who received less than 6 cycles of chemotherapy combined with atezolizumab in the induction phase and patients with missing laboratory data were excluded from the study. Characteristics of the patients, treatments administered, response rates and survival data were analyzed. Kaplan-Meier test was used to determine survival data and the effects of metastasis sites were analyzed using log-rank test. Results: Twenty-four patients fulfilling the criteria were included. The median age was 64 years and two thirds had comorbid disease. The median number of chemotherapy cycles was 6 (6-12) and atezolizumab cycles was 8 (6-54). After a median follow-up of 9.4 months, the median progression-free survival (PFS) and overall survival (OS) were 9.5 months (95% CI 0.0-25.8) and 30.1 months (95% CI 3.26-57.004), respectively. The overall response rate was 87.5%. There was no significant difference between the number of metastatic sites (p = 0.77) and OS. Grade 3 side effects were observed in more than half of the patients. The most common side effects were hematological toxicities, and all toxicities were manageable. Conclusion: These real-life data confirm the efficacy and safety of atezolizumab combined with at least six cycles of chemotherapy in the induction phase in the first-line treatment of extensive-stage SCLC