SDHB and gastrointestinal stromal tumor: dSDH wtGIST are a heterogeneous tumour subtype, typically presenting at a younger age and more frequently metastatic at presentation than TK-mutant GIST or SDH preserved wild-type GIST17 In contrast to TK mutant GIST, dSDH wtGIST can be indolent for long periods and median overall survival is often measured in many years,5 highlighting the need for well-tolerated therapies that are most likely to yield benefit for the individual patient.