In some embodiments the present disclosure pertains to a method of activating an anti-tumor immune response for the treatment of a cancer. In some embodiments, such a method comprises detecting CD26 expression in a subject in need thereof. In some embodiments, the method comprises administering to the subject a therapeutically effective amount of a composition comprising adenosine deaminase. In some embodiments, the adenosine deaminase stimulates T cell proliferation and activates maturation of macrophages or dendritic cells. In some embodiments, the present disclosure pertains to a method for targeted reduction of adenosine or deoxyadenosine in a tumor microenvironment of a solid tumor.
