Real-world incidence and spectrum of immune-related toxicity in cancer patients: A registry cohort data from a Central Coast Cancer Centre.

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Background: Immune-checkpoint inhibitors (ICIs) have transformed outcomes across a broad range of solid malignancies, however immune-related adverse events (irAEs) remain a major source of morbidity, treatment interruption and healthcare utilisation. Data from real-world, particularly in regional areas, remains limited. We aimed to characterise the incidence, grading and treatment context of irAEs among patients treated with ICIs across multiple tumour types within a large regional Australian health district. Methods: We conducted a retrospective cohort study of adult patients treated with ICIs between 2017 and 2026 at Gosford and Wyong tertiary hospitals of Australian Central Coast. Eligible patients had a confirmed diagnosis of solid malignancy and received at least one dose of an ICI. Clinical data collected included demographics, cancer type, line of therapy, therapeutic regimen and documented irAEs graded according to CTCAE criteria (version 6.0). Results: A total of N = 974 patients were included. Treatment exposure consisted of single-agent checkpoint inhibitor in 42% (n = 412), chemoimmunotherapy in 43% (n = 419), and combination ICI in 15% (n = 143). Overall, 156 patients (16%) developed at least one irAE. The most common irAEs were dermatologic (38/156), gastrointestinal (29/156), hepatic (25/156), endocrine (21/156) musculoskeletal (18/156) and pulmonary (17/156) toxicities. Rare but clinically significant irAEs included ocular toxicity (2/156), bullous pemphigoid (2/156), neuropathy (3/156), adrenal insufficiency (6/156) and acute kidney injury (8/156). Grade ≥3 irAEs occurred in 20% (31/156) of patients. 8% (12/156) of patients experienced multisystem immune toxicity involving more than one organ system. Treatment interruption due to irAEs occurred in 68% (106/156) and permanent discontinuation in 34% (54/156). Hospitalisation related to irAEs was required in 22% (35/156) of cases, with systemic corticosteroids representing the mainstay of management and selected cases (13/156) requiring escalation to advanced immunosuppressive therapy (infliximab, IVIG, mycophenolate mofetil). Conclusions: Our findings underscore the importance of early recognition, multidisciplinary management and risk stratification in routine practice. This study provides valuable real-world evidence of irAEs from a regional cancer centre highlighting the heterogeneity and clinical burden of toxicity and supports ongoing efforts to optimise toxicity surveillance and management as ICI use continues to expand.