Integrated cellular, proteomic and metabolomic profiling of immune-related adverse events in non-small cell lung cancer.

Introduction: Immune checkpoint inhibitor (ICI) therapy has become standard of care for late stage non-small cell lung cancer (NSCLC), producing durable responses in a subset of patients. However, inflammatory side eKects termed immune-related adverse events (irAEs) occur in up to 40% of ICI-treated NSCLC patients. Current approaches to alleviate irAEs include treatment with immune-suppressing corticosteroids. However, these treatments may undermine the eKicacy of ICIs by suppressing both the irAE and the anti-tumour immune response. To identify more specific therapeutic targets, a better understanding of the complex immunopathology underlying the development of irAEs in NSCLC is required. Methods: In this study, pre-treatment blood samples were prospectively collected from 72 NSCLC patients, including 23 who subsequently developed irAEs. Of these 72 samples, PBMCs from 59 were characterised using high-parameter mass cytometry. Plasma from 30 samples was analysed using the SomaScan platform that provides in depth characterisation of over 10,000 proteins, and the plasma metabolome of 30 samples was explored using liquid chromatograph-mass spectrometry (LC-MS). Results: A unique peripheral immunophenotype was observed in patients who subsequently developed irAEs, characterised by decreased memory B cell abundance, heightened Th2 immunity, and an increase in plasma cytokines. Investigation into baseline metabolites revealed dysregulation of fatty acid metabolism associated with development of irAEs. Analysis of additional paired PBMC (n = 17) and plasma (n = 12) samples collected early on treatment allowed exploration of the immunological, proteomic, and metabolic changes associated with irAE development. ICItreatment of patients who developed irAEs induced a significant increase in the abundance of CD8 memory cells and plasma histones. This points to the induction of a strong and potentially pathogenic immune response early following ICI treatment in patients who subsequently develop overt toxicity. Discussion: Overall, through application of a high-parameter multiomic approach, we have identified key cellular, proteomic and metabolomic features that predispose patients to developing immunotherapy toxicity. These findings provide insight into the complex biology underlying the development of ICI-related adverse events and inform potential treatment strategies.