While immune checkpoint blockade (ICB) (CTLA4/ PD1) therapy has resulted in durable responses in patients with advanced stage cutaneous melanoma, some patients do not benefit from this, due to... Show moreWhile immune checkpoint blockade (ICB) (CTLA4/ PD1) therapy has resulted in durable responses in patients with advanced stage cutaneous melanoma, some patients do not benefit from this, due to resistance mechanisms. This thesis aims to improve response of a subset of melanoma patients to immunotherapy. Firstly, mouse melanoma tumor models are developed that closely resemble some of the resistance mechanisms occurring in patient tumors, which are useful for research. Thereafter, a prognostic biomarker is used to identify the subset of melanoma patients that are unlikely to benefit from ICB therapy. It is then evaluated whether this subset of patients would benefit from combining histone deacetylase inhibitor with ICB. Despite encouraging pre-clinical results showing enhanced anti-tumor immune responses using this combination, this did not result in improved responses in the clinic. Furthermore, this thesis focuses on an immune cell subset, namely regulatory T cells (Tregs), which are known to suppress anti-tumor immune responses. Thus, their presence in the tumor microenvironment (TME) is detrimental to tumor cell killing. This thesis provides an increased understanding of the metabolic adaptation of Tregs to conditions in the TME and propose that targeting these adaptations might overcome the suppression by Tregs and enhance responses to immunotherapy. Show less
Metabolic reprogramming of cancer cells generates a tumour microenvironment (TME) characterised by nutrient restriction, hypoxia, acidity and oxidative stress. While these conditions are... Show moreMetabolic reprogramming of cancer cells generates a tumour microenvironment (TME) characterised by nutrient restriction, hypoxia, acidity and oxidative stress. While these conditions are unfavourable for infiltrating effector T cells, accumulating evidence suggests that regulatory T cells (Tregs) continue to exert their immune-suppressive functions within the TME. The advantages of Tregs within the TME stem from their metabolic profile. Tregs rely on oxidative phosphorylation for their functions, which can be fuelled by a variety of substrates. Even though Tregs are an attractive target to augment anti-tumour immune responses, it remains a challenge to specifically target intra-tumoral Tregs. We provide a comprehensive review of distinct mechanistic links and pathways involved in regulation of Treg metabolism under the prevailing conditions within the tumour. We also describe how these Tregs differ from the ones in the periphery, and from conventional T cells in the tumour. Targeting pathways responsible for adaptation of Tregs in the tumour microenvironment improves anti-tumour immunity in preclinical models. This may provide alternative therapies aiming at reducing immune suppression in the tumour. Show less
Multiomic profiling of several cohorts of patients treated with immune checkpoint blockade highlights the presence and potential role of B cells and tertiary lymphoid structures in promoting... Show moreMultiomic profiling of several cohorts of patients treated with immune checkpoint blockade highlights the presence and potential role of B cells and tertiary lymphoid structures in promoting therapy response.Treatment with immune checkpoint blockade (ICB) has revolutionized cancer therapy. Until now, predictive biomarkers(1-10) and strategies to augment clinical response have largely focused on the T cell compartment. However, other immune subsets may also contribute to anti-tumour immunity(11-15), although these have been less well-studied in ICB treatment(16). A previously conducted neoadjuvant ICB trial in patients with melanoma showed via targeted expression profiling(17) that B cell signatures were enriched in the tumours of patients who respond to treatment versus non-responding patients. To build on this, here we performed bulk RNA sequencing and found that B cell markers were the most differentially expressed genes in the tumours of responders versus non-responders. Our findings were corroborated using a computational method (MCP-counter(18)) to estimate the immune and stromal composition in this and two other ICB-treated cohorts (patients with melanoma and renal cell carcinoma). Histological evaluation highlighted the localization of B cells within tertiary lymphoid structures. We assessed the potential functional contributions of B cells via bulk and single-cell RNA sequencing, which demonstrate clonal expansion and unique functional states of B cells in responders. Mass cytometry showed that switched memory B cells were enriched in the tumours of responders. Together, these data provide insights into the potential role of B cells and tertiary lymphoid structures in the response to ICB treatment, with implications for the development of biomarkers and therapeutic targets. Show less
