While MI-503 has been shown to decrease Ewing sarcoma cell proliferation and tumor growth, VTP50469, a menin inhibitor that displays significant tumor-suppressive activity in leukemia, had only a modest effect on Ewing sarcoma tumor growth in a xenograft mouse model [354], indicating that only specific menin inhibitors may be effective for treating Ewing sarcoma. This evidence concerns the gene MEN1 and Ewing sarcoma.