Immune Landscape and Tumour Heterogeneity in Ovarian Cancer: Insights From Single-Cell RNA Sequencing

Tumour heterogeneity is a key factor in cancer progression, with immune responses within the tumour microenvironment (TME) contributing significantly to treatment resistance and immunotherapy outcomes. Recent advances in single-cell RNA sequencing (scRNA-seq) have provided unprecedented insights into the diverse immune cell populations infiltrating tumours, including both innate immune cells like dendritic cells, neutrophils, macrophages, and natural killer (NK) cells, as well as adaptive immune cells such as T lymphocytes. The immune landscape of tumours is complex and dynamic, characterised by a mixture of activated and suppressed immune states that evolve over time. The degree of immune cell infiltration varies among tumour types and disease stages, influencing tumour response to therapies. For example, ovarian cancer typically exhibits weaker immune infiltration compared to cancers like melanoma and non-small cell lung cancer. Increased CD8+ T cell infiltration is generally associated with favourable prognosis, while elevated regulatory T cells (Tregs) can suppress anti-tumour immune responses. The use of scRNA-seq has enabled detailed profiling of immune cells, revealing the roles of exhausted T cells and immunosuppressive macrophages in the TME. This high resolution approach facilitates the identification of distinct immune cell subsets and their functional states, providing a platform for developing more targeted, personalised immunotherapies. The findings offer promising avenues for improving clinical outcomes in ovarian cancer and other malignancies through refined immune profiling.