The present invention relates to chemical compounds that can in particular be used as structural mimetics of proline-rich peptides. The compounds of the present invention are capable of selectively inhibiting ena/VASP-EVH1-mediated protein-protein interactions. The invention further relates to the use of said compounds as pharmaceutical agents and to the use of the pharmaceutical agents to treat tumor diseases. The chemical compounds of the present invention can significantly inhibit the chemotaxis and motility of invasive tumor cells and can therefore be used in the treatment and/or prevention of tumor metastases.