Abstract: Provided are an antigen binding protein capable of binding to PD-1 and a fusion protein thereof, and corresponding preparation method therefor and the use thereof. The fusion protein is capable of targeting PD-1 and CD73.

Abstract: Provided an isolated antigen binding protein having one or more of the following properties: a. capable of binding to both human CD73 and Cynomolgus monkey CD73; b. capable of inhibiting 5?ectonucleotidase activity of CD73; c. capable of mediating CD73 internalization; d. capable of promoting T cell proliferation; e. with a relatively stable concentration in serum; and f. capable of inhibiting tumor growth and/or tumor cell proliferation. In addition, provided a method for producing the isolated antigen binding protein as well as pharmaceutical uses of the isolated antigen binding protein in preventing, alleviating and/or treating tumor.