Drug Repurposing Identifies a Synergistic Combination Therapy with Imatinib Mesylate for Gastrointestinal Stromal Tumor

摘要

Gastrointestinal Stromal Tumor (GIST) is a rare and therefore often neglected disease. Introduction of the kinase inhibitor, imatinib mesylate (IM) radically improved the clinical response of patients with GIST; however, its effects are often short-lived, with GISTs demonstrating a median time to progression of approximately two years. Although many investigational drugs, approved first for other cancers, have been subsequently evaluated for the management of GIST, few have greatly impacted the overall survival of patients with advanced disease. We employed a novel, focused, drug repurposing effort for GIST including IM-resistant GIST evaluating a large library of FDA-approved drugs regardless of current indication. As a result of the drug repurposing screen, we identified eight FDA-approved drugs including fludarabine phosphate (F-AMP) that showed synergy with and/or overcame resistance to IM. F-AMP induces DNA damage, annexin V and caspase 3/7 activities as the cytotoxic effects on GIST cells, including IM-resistant GIST cells. F-AMP and IM combination treatment showed greater inhibition of GIST cell proliferation when compared to IM alone and F-AMP alone. Successful in vivo experiments confirmed the combination of IM with F-AMP enhanced the antitumor effects compared to IM alone. Our results identified F-AMP as a promising, repurposed drug therapy for the treatment of GISTs, with potential to be administered in combination with IM or for treatment of IM-refractory tumors.