1540P Real-world analysis of outcomes of first-line chemo-immunotherapy in patients with extensive disease small cell lung cancer (ED-SCLC)

Abstract

SCLC accounts for approximately 13% of lung cancer diagnoses. For the more than 70% of patients diagnosed with ED-SCLC the standard of care 1L-treatment is platinum and etoposide in combination with PD-L1 blockade, based on the 2-month improvement in median overall survival (OS) in two randomized phase III trials. Yet, the efficacy and safety of first-line chemo-immunotherapy in patients with ED-SCLC in a real-world setting remains unclear. Patients with ED-SCLC who received first-line ICI in combination with platinum-based chemotherapy at ten cancer centers in Switzerland were included in this retrospective analysis. Responses were assessed by the local investigators using standard RECIST v1.1 criteria. Progression-free survival (PFS) and OS were analyzed by the Kaplan-Meier method. 200 patients were included between October 2018 and October 2021. Mean age was 67 years, 117 (58.5%) were males, 125 patients (62.5%) were current and 68 (34.0%) former smokers. 39 patients (25.3%) had a performance status (PS) ≥2. 185 patients (92.5%) were diagnosed with ED-SCLC, 15 patients (7.5%) had a relapse after initial limited disease stage treatment. The majority of patients was treated with atezolizumab (n=190, 95.5%) in combination with chemotherapy, 4.5% received durvalumab. 69 patients (35.2%) had undergone radiotherapy (RT) prior to or during ICI. At the time of analysis, 132 patients (66.0%) have died. Median duration of response was 2.6 months. Median PFS and OS were 6.1 and 11.0 months, respectively. The overall response rate was 75.2%. Immune-related adverse events were seen in 25.0% of patients with no new safety signals. Most frequent sites of tumor progression were lung (21.5%), lymph nodes (19.5%) and brain (15.4%). 112 patients (56.6%) received another systemic therapy after combined chemo-immunotherapy. This is the largest retrospective analysis of outcomes of 1L chemo-immunotherapy in patients with ED-SCLC in the real-world setting also including patients with ECOG PS ≥2. Outcomes in this real-world cohort are comparable to data in the pivotal trials. It will be important to better characterize the patient population that benefits most from this treatment strategy.