The present invention involves the pharmaceutical field, including integrin antagonists, which have the capacities of inhibiting angiogenesis of tumors, binding integrin. These antagonists are a kind of polypeptide, which was modified by polyethylene glycol and after modification, it can be used to treat tumors. The sequence and structure of these antagonists is mPEG-SC20k-Ile-Val-Arg-Arg-Ala-Asp-Arg-Ala-Ala-Val-Pro-Gly-Gly-Gly-Gly-Arg-Gly-As p, which demonstrates it is scientific, reasonable and feasible in tumor treatment and greatly expands the treatment spectrum. It can provide new ideas and perspectives for drug development and has significant social and market value.
