Therapeutic targets in gastrointestinal stromal tumors

摘要

Gastrointestinal stromal tumors(GISTs) are the most common type of mesenchymal tumor of the gastrointestinal tract. The tumorigenesis of GISTs is driven by gain-of-function mutations in KIT or plateletderived growth factor receptor α(PDGFRA),resultingin constitutive activation of the tyrosine kinase and its downstream signaling pathways. Oncogenic KIT or PDGFRA mutations are compelling therapeutic targets for the treatment of GISTs,and the KIT/PDGFRA inhibitor imatinib is the standard of care for patients with metastatic GISTs. However,most GIST patients develop clinical resistance to imatinib and other tyrosine kinase inhibitors. Five mechanisms of resistance have been characterized:(1) acquisition of a secondary point mutation in KIT or PDGFRA;(2) genomic amplification of KIT;(3) activation of an alternative receptor tyrosine kinase;(4) loss of KIT oncoprotein expression; and(5) wild-type GIST. Currently,sunitinib is used as a secondline treatment for patients after imatinib failure,and regorafenib has been approved for patients whose disease is progressing on both imatinib and sunitinib. Phase Ⅱ/Ⅲ trials are currently in progress to evaluate novel inhibitors and immunotherapies targeting KIT,its downstream effectors such as phosphatidylinositol 3-kinase,protein kinase B and mammalian target of rapamycin,heat shock protein 90,and histone deacetylase inhibitor. Other candidate targets have been identified,including ETV1,AXL,insulin-like growth factor 1 receptor,KRAS,FAS receptor,protein kinase c theta,ANO1(DOG1),CDC37,and aurora kinase A. These candidates warrant clinical evaluation as novel therapeutic targets in GIST.