Rationally Engineered Adenosine A2A Decoy Receptor for Reversing Immunosuppression of Breast Cancer.

The hypoxia-adenosine axis drives tumor immune evasion by activating A2AR on immune cells, and current therapeutic strategies predominantly rely on small-molecule antagonists. However, these agents face limitations including short plasma half-life, off-target effects on other adenosine receptors, and inability to remodel the physical barriers of solid tumors. To overcome these challenges, this work designs a novel adenosine-A2AR protein inhibitor, A2ARQTY-Fc, which demonstrates a notably high binding affinity for NECA and exhibits good water solubility and stability both in vitro and in vivo. This protein effectively blocks T cell A2AR signaling and restores cytokine production disrupted by NECA. Furthermore, given that the immune rejection microenvironment of solid tumors can impede the physical contact-dependent tumor immune killing, this work designs a hydrogel drug delivery system based on human hair keratin. In a mouse model of 4T1 breast cancer, in situ injection of A2ARQTY-Fc loaded keratin hydrogel significantly inhibited tumor growth, reduced extracellular matrix density, and promoted immune cell infiltration. These findings demonstrate that combining the A2ARQTY-Fc with keratin hydrogel-mediated delivery not only disrupts the hypoxia-adenosine immunosuppressive axis, but also physically remodels the tumor microenvironment, thereby establishing a dual-targeted therapeutic paradigm for overcoming GPCR-mediated immune evasion and matrix barriers in solid tumors.