Aims: Atezolizumab was listed on the pharmaceutical benefits scheme in March 2020 for use in combination with carboplatin and etoposide for first line treatment of extensive stage small cell lung cancer (ES-SCLC) based on the IMpower133 study. We aimed to investigate the survival benefits of additional Atezolizumab to platinum doublet chemotherapy for ES-SCLC in the real-world setting.
Methods: Retrospective single centre study. Patients were identified from hospital databases. Group A commenced chemotherapy alone from September 2018 to March 2020 while Group B commenced treatment with chemotherapy plus Atezolizumab between March 2020 to June 2021. Data collection variables included patient demographics, date of diagnosis, number of cycles received, reason for stopping treatment and date of death. All patients were followed for 15 months. Results were analysed through a Kaplan-Meier method.
Results: Thirty-one patients were included in the study, fifteen in group A (chemotherapy) and sixteen in group B (Atezolizumab). Patients in both groups received carboplatin and etoposide. The median age at diagnosis was 69.5 years, similar for both groups. The median overall survival was 6 months for group A compared to 8.1 months for group B. Overall survival rate at 15 months was 13.3% in group A compared to 25% in group B. In the IMpower133 study, the overall survival outcome was 10.3 months in platinum-doublet chemotherapy and 12.3 months in Atezolizumab combination with chemotherapy. Three patients were continuing maintenance Atezolizumab at the end of the study period. Ten patients stopped Atezolizumab due to disease progression and three patients due to toxicity.
Conclusion: The addition of Atezolizumab to platinum-doublet chemotherapy for treatment of ES-SCLC at our institute resulted in increased median overall survival. Although the survival times are shorter in both groups compared to IMpower133, we demonstrate a comparative benefit of adding Atezolizumab in the real-world setting.