A study led by USC researchers found that high-dose corticosteroid use in non-small cell lung cancer (NSCLC) patients undermines the efficacy of immune checkpoint inhibitors (ICIs). The steroids impede maturation of T cells, critical for immune-mediated tumor attack, resulting in reduced tumor shrinkage and survival. This mechanistic insight helps explain clinical observations of immunotherapy failure in steroid-treated patients and underscores careful management of corticosteroid therapy during cancer immunotherapy, as reported in Cancer Research Communications.