A single-centre experience of immune checkpoint inhibitors in patients with cancer in the Top End of the Northern Territory, Australia from 2016 to 2021.
Authors: Miller Abigail Rose , Balino Aries , Tun Min Sandy , Butt Sabeeh , Karanth Narayan Vaderahobali , Charakidis Michail 
Published: June 2023

e18841 Background: Immune checkpoint inhibitors (ICI) have transformed the oncological landscape, but are associated with immune-related adverse events (irAE) of varying frequency and severity. This regional single-centre experiential study evaluates the real-world incidence of irAE in patients in the Top End of the Northern Territory of Australia. The Top End represents a diverse population with high proportions of Aboriginal and Torres Strait Islander (ATSI) patients and patients living in remote and very remote areas. This captured cohort is under-represented in clinical trials. Methods: We identified all patients with solid tumours who were prescribed ICI between January 2016 and December 2021. We manually reviewed electronic and paper hospital records to record patient characteristics, treatments received, irAE, irAE treatment and patient outcomes. Results: 226 patients across 11 solid tumour streams received ICI. Of these, 58% had lung cancer, 27% melanoma, 5% head & neck cancer, 4% renal cell carcinoma, and the remainder other tumour streams. 70% were male and the median age at diagnosis was 63 years [28-84 years]. 16% identified as ATSI(compared to 2.8% ATSI nation-wide and 26.3% ATSI in the Northern Territory). Of the investigational cohort, 13% were treated in the adjuvant and 87% in the palliative setting. 11% received combination versus 89% single-agent ICI. 30% of patients had concurrent chemotherapy. 122 patients (54%) experienced any grade irAE as documented by the treating oncologist in the medical records. 59 patients (26%) had a severe (grade 3, 4, or 5) irAE. The fatality rate was 0.88% (2 patients); both were treated with a PD-L1 inhibitor for non-small cell lung cancer (NSCLC) and diagnosed with immune-related pneumonitis. The most common irAE were rash (18%), colitis (16%), arthralgia/myalgia (13%), pneumonitis (12%), thyroiditis/hypothyroidism (12%), hepatitis (9%), and adrenal insufficiency (7%). 24% of irAE required hospitalisation and 32% led to discontinuation of treatment. The median number of irAE per patient was 1. Among patients with the most common tumour types (melanoma and NSCLC), rates of irAE were, in both cases, 59% any grade irAE and 20% severe irAE. When compared to published literature, real-world rates of any grade adverse event were significantly lower than reported number in trials – likely due to exclusion of common non-immune-related adverse events in our data set. Rates of severe and fatal irAE were in line with published data. Conclusions: Immune-related adverse events are common among patients in the Top End and reflect rates in the published literature. We did not identify any safety concerns in our cohort of patients – including amongst ATSI patients and those living in remote and very remote areas. Further data analysis is needed to assess frequency and severity of irAE by specific tumour type and ICI.