Impact of immune-related adverse events on survival in patients with advanced non-small cell lung cancer treated with immune checkpoint inhibitors: A real-world perspective.
Authors: Rizwan Saleha , Alhamad Khaled , Abel Stephen , Bakalov Veli , Rodriguez Robin Raquel , Sethi Ashish , Khan Talal , Attah Abraham Attah , Yasir Muhammad , Shankar Karthik , Lo Herman , Friday Andrew , Finley Gene Grant 
Published: June 2021

e21213 Background: Lung cancer is the leading cause of death in males and females in the United States. Approximately 85% of all cases are classified as non-small cell lung cancer (NSCLC) with majority diagnosed at an advanced stage. Unfortunately, response to traditional chemotherapy (ChT) has been poor with a five-year survival rate of 6% in metastatic NSCLC. Immune checkpoint inhibitors (ICI) have changed the therapeutic landscape for advanced NSCLC and are being utilized alone or in combination with ChT as the standard first-line therapy. With widespread use of ICIs, immune-related adverse events (irAE) are commonly seen and in some studies their occurrence correlates with improved outcomes. The aim of our study was to evaluate whether development of irAEs has an impact on survival in NSCLC. Methods: We performed a retrospective analysis on stage IV NSCLC patients treated with ChT, ChT plus ICI, or ICI monotherapy from December 2016 to December 2019. Univariable and multivariable analyses identified characteristics predictive of progression-free survival (PFS) and overall survival (OS). OS was calculated using Kaplan Meier curves. Log-rank statistics were used to assess statistical significance between groups. Multivariable logistic regression was performed to identify predictors of survival. Results: 193 patients were evaluated out of which 92 (47.2%) received ChT plus pembrolizumab, 69 (35.4%) received pembrolizumab alone and 32 (16.4%) received ChT alone. 130 patients were found to have no irAEs compared to 57 patients who were noted to have any grade of irAE. The median PFS was 17.4 months (irAE group) vs. 8.5 months (non-irAE group) with hazard ratio (HR) of 0.58 (95% CI: 0.41 to 0.80, p = 0.001). The median OS was 29.4 months (irAE group) vs. 14.4 months (non-irAE group) with HR of 0.56 (95% CI: 0.39 to 0.82, p = 0.0026). A multivariate analysis was performed for age, gender, ECOG performance status, insurance status, BMI, PDL1 status and smoking history, amongst other variables. Worse survival outcomes were noted with an ECOG performance status ≥ 2, no history of smoking, and involvement of palliative care. Multivariable logistic regression analysis showed that PDL-1 expression > 50% was the only predictor of developing an irAE. Of note, receipt of ChT in combination with pembrolizumab compared to pembrolizumab alone did not predict for development of irAE. Conclusions: Development of irAEs was associated with doubling of PFS and OS, regardless of whether the ICI was administered alone or in combination with ChT. The differences were statistically significant regardless of age, gender, race, BMI, insurance status or performance status. Our study highlights the correlation between development of irAEs and improved survival outcomes in advanced NSCLC patients treated with ICIs.