A turning point for cancer treatment: monocytes boost T-cells in immunotherapy

Scientists led by Anna Obenauf at the Research Institute of Molecular Pathology (IMP) now discovered the crucial role of a type of immune cell—inflammatory monocytes—in reactivating cancer-killing T cells within tumours. The findings, published in the journal Nature, make monocytes a promising target to boost immunotherapies, potentially benefitting patients affected by a range of cancers, including melanoma, lung, pancreatic, and colorectal cancer.

Computer-rendered image showing T cells (red) interacting with monocytes (yellow) and dendritic cells (blue) in the tumour microenvironment. These interactions help T cells to fully mature and effectively target and kill cancer cells. The scale bar (white) represents 10 micrometres (µm), indicating the size of the tumour regions shown.

Over the past decades, immunotherapy has transformed cancer treatment, offering effective options for diseases once considered uncurable, such as melanoma, lung, and bladder cancers. What began as laboratory research has now moved to real-world clinical applications, providing new possibilities for patients facing a range of challenging conditions.

Immunotherapy works by harnessing the body’s own immune system to eliminate cancer cells, either by broadly enhancing immune activity or by targeting specific pathways to recognise, attack, and destroy these cells.

While immunotherapy has made remarkable progress in treating patients, significant challenges persist. Chief among these is cancer’s ability to evade the immune system—by altering its cells to avoid detection and suppressing immune responses through the establishment of an immune-evasive tumour microenvironment. As a result, a substantial number of patients do not respond to current therapies. For example, over 50 percent in the case of those affected by melanoma, the most aggressive form of skin cancer.

Much of how cancer evades the immune response remains unknown, largely due to the complex cascade of molecular events in the interactions between cancer and immune cells. Understanding the nuances of these processes will be key to developing more effective therapies.

In a study led by Anna Obenauf, Senior Group Leader at the Research Institute of Molecular Pathology (IMP), an international team of researchers integrated cutting-edge tools, including melanoma mouse models, single-cell RNA sequencing, and advanced functional genetics and imaging technologies, to push the boundaries of our understanding of the immune system’s role in fighting cancer. The study, now published in the journal Nature, reveals an additional type of immune cell involved in stimulating the immune response against cancer, opening up possibilities for new strategies to boost immunotherapy and potentially expand its benefits to more patients.

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