Corticosteroid (CS) use and risk of adverse events (AEs) in patients (pts) treated for metastatic hormone-sensitive prostate cancer (mHSPC).

e17097 Background: Treatment (Tx) of mHSPC involves intensifying androgen-deprivation therapy (ADT) with androgen receptor pathway inhibitors (ARPIs; abiraterone, darolutamide, enzalutamide, apalutamide) with/without docetaxel (D). Abiraterone and D are typically co-administered with CS to mitigate AEs, while other ARPIs are administered without CS. CS exposure is associated with AEs such as infection, cardiovascular events, and endocrine disorders in pts with castration-resistant prostate cancer (CRPC). This study evaluated the association between CS exposure and AEs in pts with mHSPC. Methods: Per a predefined protocol, an observational cohort study was conducted using Medicare Parts A, B, and D data among pts ≥65 years old initiating mHSPC Tx from 6/1/2017. Pts were followed up from time of Tx initiation until time of first AE, initiation of a different Tx, diagnosis of mCRPC, death, end of enrollment, or 12/31/2023. Multivariable Cox proportional hazards models were used to evaluate the association between CS exposure (binary time-varying variable, defined as ≥1 daily dose of ≥5 mg prednisone-equivalent CS during the follow-up period) and risk of prespecified AEs and death, adjusted for baseline demographic and clinical characteristics, AEs, and healthcare utilization in the 1 year prior to index, as well as average daily dose of CS over all available times prior to index. Results: Overall, 24,857 pts with mHSPC (51% CS exposed and 49% not CS exposed) were included in the analysis. Median age was 78 (IQR: 12) years. First-line Tx for mHSPC included ADT alone (17%), ADT + ARPI +/− D or ADT + nonsteroidal antiandrogen (NSAA) (37%), and other Tx (ADT + D, NSAA alone, etc.) (46%). Pts exposed to CS during follow-up tended to be younger, had fewer prior hospitalizations, and had less history of heart failure, diabetes, and anemia before the index date than those not exposed to CS. Compared with pts not exposed to CS, those exposed to CS were at significantly higher risk of all AE types, except ophthalmic AEs (Table), and had a 34% higher risk of all-cause death (adjusted HR [95% CI], 1.34 [1.27–1.42]). The greatest increase in risk was observed for infections, fluid and electrolyte disturbances, and hematologic AEs. The effect of CS exposure on AE risk was similar for younger (i.e., ≥65 to <75 years) and older pts (≥75 years). Conclusions: Among pts with mHSPC, CS exposure was associated with increased risk of nearly all categories of AEs and death. These data can help guide pt counseling and Tx selection. AE type Adjusted HR (95% CI), Exposed vs Unexposed Infection 1.52 (1.44–1.61) Fluid and electrolyte disturbance 1.46 (1.40–1.53) Hematologic 1.35 (1.28–1.43) Gastrointestinal 1.22 (1.04–1.44) Musculoskeletal 1.21 (1.15–1.28) Endocrine and metabolic 1.17 (1.12–1.22) Dermatologic 1.14 (1.08–1.21) Cardiovascular 1.08 (1.04–1.12) Ophthalmic 1.06 (0.98–1.13)