1284PReal world outcomes of immune-related adverse events (irAEs) among patients receiving immune checkpoint inhibitors (ICIs) in hospital settings

Abstract Background With the increased use of ICIs among cancer patients, there is growing interest in understanding the outcome and management of irAEs. This study addressed this knowledge gap by examining the real-world outcomes in patients experiencing irAEs. Methods An observational study was conducted using the Premier Healthcare Database, a US national hospital discharge database (Mar 2015-Dec 2017). Twenty-eight distinct types of irAEs per the ASCO practice guidelines were identified. Patients with ICD-9/10 codes for NSCLC, RCC, UC, or MCC and one of 28 irAEs during the study period were included. Index irAE visits were defined as the first visit with a confirmed ICI usage during a 90-day look-back period from the first irAE. Patients were then followed for 90 days post-irAE to determine irAE-related inpatient admissions, all-cause in-hospital mortality, and ICI re-initiation. Results 15,277 distinct irAEs occurred across 13,030 patients, with 5,732 (38%) of irAE events with an inpatient index visit. Among the 6590 patients having ≥1 irAEs, 44% had 1 irAE of any type, 25% had 2, 14% had 3, and 17% had ≥4 irAEs. Among the 28 types of irAEs, inpatient index visits were most common for myocarditis, transverse myelitis, and toxic epidermal necrolysis (all 100%), and least common for acquired hemophilia (0%), polymyalgia-like syndrome (10%), and adrenal insufficiency (10%). During the follow-up period, patients with inpatient index admissions had higher (p Conclusions Approximately half of patients receiving an ICI experienced an irAE that required clinical management in inpatient or outpatient setting. Occurrence of irAEs was associated with treatment discontinuation. Overall, irAE cases with inpatient index visits tended to have poor outcomes and required more follow-up management. Table . 1284P Index Visit Type Clinical outcome: 90 days following index irAE All Inpatient Outpatient irAE-related inpatient admission 23% 26% * 19% * No ICI re-initiation 47% 70% ** 28% ** All-cause inpatient mortality 12% 23% *** 6% *** * p ** p *** p Legal entity responsible for the study EMD Serono, Inc. Funding This study was sponsored by EMD Serono, Inc, a business of Merck Healthcare KGaA, Darmstadt, Germany, and is part of an alliance between EMD Serono/Merck Healthcare KGaA, Darmstadt, Germany and Pfizer Inc., New York, NY, USA. Disclosure S. George: Advisory / Consultancy, Research grant / Funding (institution): Bayer; Advisory / Consultancy, Research grant / Funding (institution): BMS; Research grant / Funding (institution): Novartis; Advisory / Consultancy: Exelixis; Advisory / Consultancy: Janssen; Advisory / Consultancy, Research grant / Funding (institution): Corvus; Advisory / Consultancy: Genentech; Advisory / Consultancy: Sanofi/Genzyme; Advisory / Consultancy, Research grant / Funding (institution): Pfizer, Inc; Research grant / Funding (institution): Acceleron; Research grant / Funding (institution): Merck ; Research grant / Funding (institution): Agensys; Research grant / Funding (institution): Eisai; Advisory / Consultancy: EMD Serono, Inc. Y. Zheng: Full / Part-time employment, current employment (self): EMD Serono, Inc; Full / Part-time employment, previous employment (self) : Janssen; Licensing / Royalties, Full / Part-time employment, spouse and immediate family: Shire (now Takeda); Full / Part-time employment, spouse: Eli Lilly. R. Kim: Full / Part-time employment: Pfizer, Inc.; Shareholder / Stockholder / Stock options: Exelixis. T. Yu: Full / Part-time employment: EMD Serono, Inc. J. Dreyfus: Shareholder / Stockholder / Stock options, Full / Part-time employment: Premier, Inc. J.A. Gayle: Full / Part-time employment: Premier, Inc. C. Wassel: Full / Part-time employment: Premier, Inc. H. Phatak: Full / Part-time employment: EMD Serono, Inc.