11136 Background: Immune checkpoint inhibitors (ICIs) are a mainstay of treatment for many cancers but can cause immune-related adverse events (irAEs) that require prompt recognition and management. In 2017, we developed an online interactive decision support tool [www.clinicaloptions.com/immuneAEtool] for healthcare providers (HCPs) with case-specific recommendations for managing irAEs from a medical oncology expert. In 2019 and 2023, we updated the tool to offer recommendations from the latest National Comprehensive Cancer Network (NCCN) Guidelines. Here, we report a comparison of self-reported irAE management from HCPs using the 2023 tool vs NCCN recommendations and a comparison of practice patterns between the 2023 and 2019 tools. Methods: To use the online tool, HCPs entered the affected organ system, symptom grade/severity, and their planned management strategy. The tool showed the NCCN management recommendation for that irAE and then asked if the recommendation changed their intended management approach. Results: From July to December 2023, 172 HCPs entered 241 case scenarios into the tool; 53% treated <10 patients/month with ICIs, and 38% of HCPs practiced in the United States. The most common irAEs involved the gastrointestinal (GI)/hepatobiliary (hep)/pancreatic (29% of cases) or dermatologic/oral (19%) systems. Overall, the planned irAE management strategy of HCPs matched the NCCN recommendations in 55% of cases, an increase from the 49% concordance rate in our 2019 analysis. In the current analysis, the lowest concordance was observed for infusion-related reactions (20%), musculoskeletal irAEs (46%), and dermatologic/oral mucosa irAEs (46%; Table). Furthermore, US HCPs had a lower overall concordance rate (46%) than non-US HCPs (66%). Approximately one half (56%) of all HCPs indicated that the NCCN recommendations in the tool changed their management plan. Conclusions: These data suggest that many HCPs are challenged to optimally manage irAEs and are not managing their patients in concordance with NCCN guidelines. A detailed analysis of HCP irAE management vs NCCN recommendations, including by organ system and severity, along with a comparison of 2023 vs 2019 practice patterns, will be presented. [Table: see text]