Abstract

PURPOSE: Gastrointestinal stromal tumor (GIST) is the most common sarcoma of the gastrointestinal tract with mutant succinate dehydrogenase (SDH) subunits (A-D) comprising less than 7.5% (i.e. 150-200/year) of new cases annually in the United States. Contrary to GISTs harboring KIT or PDGFRA mutations, SDH-mutant GISTs affect adolescents/young adults, often metastasize, and are frequently resistant to tyrosine kinase inhibitors (TKIs). Lack of human models for any SDH-mutant tumors, including GIST, has limited molecular characterization and drug discovery.EXPERIMENTAL DESIGN: We describe methods for establishing novel patient-derived SDH-mutant (mSDH) GIST models and interrogated the efficacy of temozolomide on these tumor models in vitro and in clinical trials of mSDH GIST patients.RESULTS: Molecular and metabolic characterization of our patient-derived mSDH GIST models revealed that these models recapitulate the transcriptional and metabolic hallmarks of parent tumors and SDH-deficiency. We further demonstrate that temozolomide elicits DNA damage and apoptosis in our mSDH GIST models. Translating our in vitro discovery to the clinic, a cohort of SDH-mutant GIST patients treated with temozolomide (n=5) demonstrated a 40% objective response rate and 100% disease control rate suggesting that temozolomide represents a promising therapy for this subset of GIST.CONCLUSION: We report the first methods to establish patient-derived mSDH tumor models, which can be readily employed for understanding patient-specific tumor biology and treatment strategies. We also demonstrate that temozolomide is effective in mSDH GIST patients who are refractory to existing chemotherapeutic drugs (namely TKIs) in clinic for GISTs, bringing a promising treatment option for these patients to clinic.

View details for DOI 10.1158/1078-0432.CCR-21-2092

View details for PubMedID 34426440