Real World Efficacy and Safety of First Line Chemo Immunotherapy in Extensive Stage Small Cell Lung Cancer and its association with molecular subtype.

[PURPOSE] Small cell lung cancer (SCLC) is an aggressive malignancy with poor outcomes. IMpower133 and CASPIAN established platinum-etoposide plus anti-PD-L1 antibody as standard first-line therapy for extensive-stage SCLC (ES-SCLC). Real-world data in Korean patients are scarce. We evaluated the effectiveness and safety of first-line chemo-immunotherapy in ES-SCLC and compared outcomes with pivotal trials.

[MATERIALS AND METHODS] We retrospectively reviewed patients diagnosed with ES-SCLC between 2018 and 2021. Overall survival (OS), progression-free survival (PFS), and time to next treatment (TTNT) were analyzed using Kaplan-Meier methods. Multivariate Cox regression identified prognostic factors. Objective response rate (ORR) was assessed by RECIST v1.1, and histological subtypes evaluated.

[RESULTS] Among 177 patients, median age was 66 years (range, 42-91), with 63.8% aged ≥65; most were male (92.7%) and ECOG 0-1 (91.5%). Smoking history was present in 80.8%. Baseline brain and liver metastases occurred in 27.7% and 26%. Median follow-up was 27.2 months (range, 3.9-43.2). ORR was 74.5% (95% CI, 67.1-81.1). Median OS, PFS, and TTNT were 12.4 (95% CI, 11.6-14.9), 5.3 (95% CI, 5.1-5.87), and 5.6 months (95% CI, 1.43-38.27). In 49 patients with brain metastases, ORR was 63.2%, with no difference in efficacy. Local therapy for brain metastases improved OS (HR 0.42; p=0.012), while PFS was not different. Treatment-related adverse events occurred in 90%, primarily grade ≥2 cytopenias; the most common immune-related event was grade 1 rash.

[CONCLUSION] In this real-world Korean cohort, first-line chemo-immunotherapy achieved outcomes comparable to pivotal trials, supporting its role as standard care for ES-SCLC in clinical practice.