title: An Investigation into the Immunological Mechanisms of Immune Related Adverse Events Associated with Oncological Immune Checkpoint Inhibitors
Creators: name: Olsson-Brown, Anna
Publisher: name: University of Liverpool Repository
Year: 2023

description: Introduction Oncological immune checkpoint inhibitors (ICIs) are now considered standard of care for the treatment of numerous malignancies. On-target off-tissue effects can lead to immune-related adverse events (irAEs) affecting multiple organ systems with severe or life-threatening toxicity occurring in 20-60% of cases. With the increasing use of ICIs, the impact of irAEs is becoming a significant concern. Despite this, the real-world experience of irAEs and current understanding of pathological mechanisms remains poor and treatments generic and non-evidence based. Methods Local, dual- and multi-centre studies were established to assess the real world manifestation of irAEs. Deep phenotyping was subsequently conducted for specific irAEs of interest including ICI-induced colitis and thyroid dysfunction. Mechanistic evaluation of irAEs was undertaken utilising a multiomic approach. Genomic evaluation via human leucocyte antigen (HLA) typing was undertaken to determine if HLA predisposes to the development of irAEs. Transcriptomic peripheral blood mRNA analysis, proteomic analysis of cytokines and both longitudinal and paired peripheral-end organ cytometric analysis was undertaken to determine key mediators of irAEs. Results The real-world incidence of irAEs showed that the use of combination immune checkpoint inhibitors and pre-existing autoimmune disease predispose to irAEs. Advancing age was not related to increasing severity of toxicity. The incidence of irAEs in the real world population was reflective of clinical trials and appeared to be tumour agnostic. There was an apparent relationship between efficacy and toxicity with improvement in survival in patients experiencing irAEs. Deep phenotyping revealed that there are numerous pathological subtypes within each organ-specific irAE. HLA analysis highlighted the potential relevance of both HLADR4 and HLADQ8 phenotypes in ICI-induced myocarditis. No other irAEs were associated with specific HLA subtypes. Elevated baseline levels of haemoglobin and albumin were found to be associated with irAEs as were early changes in neutrophil: lymphocyte ratios. Within the setting of ICI-induced colitis, differential levels of CD45+CD3-CD16+CD56+ natural killer cells, CD45+CD3+CD4+ (including CD25+CD127- T regulatory cells) and CD45+CD3+CD8+ were seen in individuals experiencing toxicity. Activated CD8+ cells and activated memory CD8+ cells were elevated in the circulation in patients with colitis. Activated memory CD8+ cells and tissue resident memory CD8+ were elevated in colonic tissue. . The expression of the colonic-homing proteins α4β7 integrin was increased in patients with severe, corticosteroid refractory ICI-induced colitis. The cellular changes were accompanied by increased activity of Toll-like receptor proteins and decreased SMAD3 expression. The levels of TNFα, TGFβ1, TGFβ2, IFN-γ and IL-6 were increased in colitis patients, but further work is required to assess the utility of cytokine clustering. Conclusions This study has identified multiple potential predictors and mediators of irAEs including HLA subtypes, cellular subpopulations, transcription factors, cell signalling complexes and cytokines. Validation of these mediators alongside robust clinical phenotyping in larger sample sizes will promote more precise identification of the relevant mediators and enable therapeutic stratification.