Co-targeting the CD73-adenosinergic axis enhances the anti-tumor efficacy of anti-PD-L1 immunotherapy in bladder cancer

Immune checkpoint inhibitors have significantly improved advanced bladder cancer care, but resistance remains a significant challenge. Adenosinergic signaling is an immunosuppressive mechanism hindered by tumor cells to escape from immune surveillance and suppress antitumor immune responses. Herein, we investigate whether co-targeting the adenosine pathway can modulate tumor immunity and enhance the efficacy of anti-PD-L1 therapy in an orthotopic murine bladder cancer model. We observed higher expression of the ectonucleotidases CD39 and CD73 in tumor cells and CD4⁺ and CD8⁺ T cells within the tumor microenvironment and peripheral circulation and upregulation of the adenosine receptors A2A and A2B in tumor cells, further confirming the activation of the adenosinergic pathway in this murine model. CD39 inhibition demonstrated no therapeutic benefits nor synergistic effect with anti-PD-L1 immunotherapy in tumor-bearing mice. On the contrary, CD73 inhibition reduced tumor progression and synergized with anti-PD-L1, leading to complete remission in 38 % of cases and a significant reduction in tumor mass in the remainder compared to anti-PD-L1 monotherapy. This combination resulted in favorable systemic immune modulation, including increased circulating CD4⁺ and CD8⁺ T cells and a decreased neutrophil-to-lymphocyte ratio. These findings suggest that the adenosinergic pathway limits the efficacy of anti-PD-L1 immunotherapy in invasive bladder cancer. Targeting the CD73 adenosinergic axis may enhance its effectiveness, offering a promising strategy to overcome resistance.