A study led by Keck Medicine USC revealed that corticosteroid use among non-small cell lung cancer (NSCLC) patients impairs the effectiveness of immune checkpoint inhibitors (ICI). High-dose steroids administered before or during immunotherapy correlated with less tumor shrinkage and shorter survival. The team identified that steroids hinder T cell maturation, offering a mechanistic explanation for diminished ICI response. These findings have significant implications for managing NSCLC treatments where steroids are commonly used to alleviate symptoms or treatment side effects.