The present invention relates to the use of pyrimidylaminobenzamide derivatives for the preparation of a drug for the treatment of FIP1L1-PDGFR.alpha.-induced or TEL-PDGFR.beta.-induced myeloproliferative diseases, especially for the curative and/or prophylactic treatment of hypereosinophilic syndrome and hypereosinophilc syndrome with resistance to imatinib, and to a method of treating hypereosinophilic syndrome, chronic eosinophilic leukemia and hypereosinophilic syndrome with resistance to imatinib, or other diseases associated with FIP1L1-PDGFR.alpha., TEL-PDGFR.beta. or similar mutations that activate PDGFR.
