(C-224) Impact of Systemic Corticosteroid Use on Survival Outcomes in Non-Small Cell Lung Cancer Patients Receiving Immune Checkpoint Inhibitors: A Retrospective Cohort Study

Background: Immune Checkpoint Inhibitors (ICIs) are used as first-line or subsequent therapy options for eligible patients with metastatic Non-Small Cell Lung Cancer (NSCLC). Systemic corticosteroids are commonly used in ICI-treated NSCLC patients for managing immune-related adverse events, cancer-related symptoms, and underlying diseases; however, evidence supporting their appropriate use remains inconclusive.

Objectives: We aimed to evaluate the impact of concomitant systemic corticosteroid use on survival outcomes in ICI-treated NSCLC patients.

Methods: This study was a retrospective cohort study utilizing the Common Data Model (CDM) based on electronic medical records (EMRs) from Seoul National University Bundang Hospital(SNUBH). A validation study was conducted using the same design and CDM framework with EMRs from Seoul St. Mary’s Hospital. The study population included patients with NSCLC who received their first ICI treatment between December 31, 2014, and December 31, 2021. The primary outcome was the 2-year overall survival (OS), while the secondary outcome was metastasis-free survival (MFS). Time-dependent propensity score matching was used to match corticosteroid non-user to corticosteroid users. Kaplan-Meier survival analysis and time-dependent Cox proportional hazards regression models were employed to estimate hazard ratios (HRs) for OS and MFS. A directed acyclic graph (DAG) was drawn to recognize confounding factors and to guide the multivariable regression model.

Results: In SNUBH, the full cohort included 659 ICI-treated NSCLC patients. A total of 109 steroid non-users were matched to 109 steroid users based on the propensity score. Kaplan-Meier analysis revealed significantly lower OS (log rank p = 0.009) and MFS (log rank p = 0.008) in corticosteroid users compared to non-users. The multivariable-adjusted hazard ratio (aHR) for corticosteroid use was 2.010 (95% confidence interval(CI): 1.865 – 2.166, p < 0.001) for the OS and 1.970 (95% CI: 1.843 – 2.106, p < 0.001) for the MFS, adjusted for immune-related adverse events identified via DAG. In a validation cohort from Seoul St. Mary’s Hospital comprising 237 ICI-treated NSCLC patients, propensity score matching resulted in two groups of 49 steroid users and 49 non-users. In the Kaplan-Meier curve, the OS (log rank p = 0.004) and MFS (log rank p = 0.005) were significantly lower in corticosteroid users. The adjusted HRs were 1.384 (95% CI: 1.285-1.491, p < 0.001) for the OS and 1.336 (95% CI: 1.241 – 1.437, p < 0.001) for the MFS.

Conclusions: The findings from our study suggested that concomitant administration of corticosteroids and ICIs may be associated with poor survival outcomes in NSCLC patients.