<prompt> Which of the following agents is recommended as first line drug for treatment of gastrointestinal stromal tumors GIST?SorafenibGeftinibImatinibErlotinib  <response>: Imatinib is drug of choice for GIST. Imatinib resistant cases can be treated with sunitinib. Tumors resistant to both imatinib and sunitinib are treated with regorafenib. 