Impact of corticosteroid exposure on long-term immune checkpoint inhibitor responses in solid tumors.

12160 Background: Multiple analyses offer conflicting evidence regarding the implications of immune related adverse events (irAE) on survival of patients with solid tumors treated with immune checkpoint inhibitor(s) (ICIs). Furthermore, the treatments used to manage irAEs also have an unclear impact on progression free survival (PFS) and overall survival (OS) on patients with solid tumors treated with ICIs. We present the PFS, OS and tumor specific survival (TSS) for pts with metastatic solid tumors treated with ICIs at an academic cancer center. Methods: 848 pts with metastatic solid tumors diagnosed between 2014 through January 2026 were identified via retrospective chart review. PFS was defined as the time from starting ICIs to progression or death, OS was defined as the time from starting ICIs to death and TSS was defined as the time from starting ICIs to death from malignancy (when available). The corticosteroid (CS) exposure was defined as low if prednisone (or equivalent) < 1mg/kg/day and/or length of exposure < / = 21 days. The CS exposure was defined as high if prednisone (or equivalent) was > / = 1mg/kg/day and/or length of exposure > / = 22 days. The CS exposure was defined as very high if prednisone (or equivalent) > 20mg/day and length of exposure was > 42 days. Steroid sparing agents were considered low impact if given once and within 14 days of starting CS. Steroid sparing agents were considered high impact if given more than once. Steroid sparing agents were considered very high impact if given more than once and/or given after 14 days of starting CS. Acute irAE was defined if symptom and immunosuppression resolved within 42 days. Chronic irAE was defined if symptom and/or immunosuppression continued beyond 42 days. The effects of CS, steroid sparing agent exposure on PFS, OS, TSS were evaluated using multivariable Cox proportional hazards models. The effect of acute irAE versus chronic irAE on PFS, OS, TSS were evaluated using multivariable Cox proportional hazards models. Results: 64.8% of patients experienced an irAE and 44.7% of patients developed G3-4 irAE requiring corticosteroids +/- steroid sparing agent. The low impact corticosteroid exposure did not affect PFS, OS or tumor specific survival. The very high impact CS exposure was associated with decrease in PFS (p = 0.02) but not with OS or TSS (p = 0.3). The high impact steroid sparing agent was associated with decrease in PFS (not significant) but the very high impact steroid sparing agent was associated with decrease in PFS. The chronic irAE was associated with slight improvement in PFS (not significant). Conclusions: The presence of an irAE was not significantly associated with PFS, OS or tumor specific survival treated with ICIs. There was a negative impact on the length of corticosteroid exposure and steroid sparing agents on PFS, TSS. The delay or interruption in treatment due to irAE did not affect survival.