The Role of the Ecto-Nucleotidases CD73 and CD39 in Chemo- and Immunotherapy

Immunotherapy, particularly effective in tumors with a high mutational burden, is very often administered in combination with chemotherapy. Several tumor types with a high mutational rate include melanoma and non-small cell lung cancer (NSCLC), which are particularly sensitive to immunotherapy. For NSCLC, conventional platinum-based doublet chemotherapy has been extended with drugs targeting signaling pathways (such as the epidermal growth factor receptor) and immune checkpoint inhibitors (ICI) directed against PD-1 and PD-L1. This review highlights the potential role of the membrane antigens CD73 and CD39 in enhancing the efficacy of combined immuno-chemotherapy. These ecto-nucleotidases catalyze the degradation of extracellular ATP to AMP and subsequently to adenosine (Ado), a potent immunosuppressive metabolite that acts through adenosine receptors. Consequently, CD73 and CD39 function as key downregulators of immunogenic signaling. Both CD73 and CD39 are highly expressed not only on tumor cells but also on immune and endothelial cells within the tumor microenvironment. Conventional chemotherapy may further upregulate their expression, contributing to drug resistance and impaired immune responses. To counteract these effects, inhibitors of CD73 and CD39, both monoclonal antibodies and small molecules, are currently under clinical evaluation, with early results indicating potential therapeutic benefit. Although this evidence supports the involvement of CD73 and CD39 in modulating responses to immunotherapy, particularly in combination with chemotherapy, the precise mechanisms underlying these interactions remain unclear. Elucidating these pathways will be critical for optimizing treatment strategies and improving clinical outcomes in malignancies such as NSCLC. This review highlights the critical role of these pathways in optimizing treatment strategies and improving clinical outcomes in malignancies such as NSCLC.