Glivec is indicated for the treatment of...adult patients with advanced hypereosinophilic syndrome (HES) and / or chronic eosinophilic leukaemia (CEL) with FIP1L1-PDGFRa rearrangement.

Gleevec is a kinase inhibitor indicated for the treatment of:…Adult patients with hypereosinophilic syndrome (HES) and/or chronic eosinophilic leukemia (CEL) who have the FIP1L1-PDGFRα fusion kinase (mutational analysis or FISH demonstration of CHIC2 allele deletion) and for patients with HES and/or CEL who are FIP1L1­ PDGFRα fusion kinase negative or unknown.

This study evaluated the efficacy and safety of imatinib in chronic eosinophilic leukaemia (CEL, n = 23) and hypereosinophilic syndrome (HES, n = 13)...Complete molecular remission (CMR) was seen in 75% (12/16) of cases with FIP1L1‐PDGFRA positive CEL by 6 months, and in 87% (13/15) after 12 months. CMR was achieved in three of five PDGFRB fusion positive patients after 3, 9 and 18 months respectively...These data confirmed the long‐term efficacy of imatinib for PDGFR‐rearranged CEL patients...