Modulation of the ATP-adenosine signaling axis combined with radiotherapy facilitates anti-cancer immunity in brain metastasis

Summary The immunosuppressive microenvironment in the brain poses a major limitation to successful therapy for brain metastases. Here we report that blockade of the ATP-to-adenosine-converting enzymes CD39 and CD73 and the adenosine receptor A2AR in combination with radiotherapy attenuates tumor progression in a breast-to-brain metastasis model by facilitating anti-cancer immunity. Immunophenotyping revealed loss of exhausted T cells and higher abundance of anti-cancer effector T cell populations. This effect was accompanied by a decrease of immunosuppressive lipid-laden macrophages and an expansion of CD14CD33high macrophages associated with antigen presentation. Analyses of human brain metastases samples supports a role of the ATP-adenosine signaling axis in modulating tumor inflammation and identified expression of CD39 and adenosine deaminase as predictive markers for patient survival and/or immune infiltration. Our findings demonstrate that the adenosine axis represents a druggable pathway to achieve local immunomodulation and treatment response, opening a new therapeutic avenue for brain metastases patients.