Temozolomide (TMZ) In Advanced Succinate Dehydrogenase (SDH)-Mutant/Deficient Gastrointestinal Stromal Tumor (GIST)

This oncology study will be a phase 2 study for patients with advanced or metastatic GIST. This study will determine overall response rate at 6 months for TMZ therapy in patients with SDH-mutant/deficient GIST. Treatment will continue for 6 months (with option to continue if benefiting treatment) or until disease progression or unacceptable toxicity (whichever occurs first). All patients will have regular evaluations for assessment of safety parameters. Temozolomide dose may be held and/or modified for the management of adverse treatment effects according to pre-specified criteria. Patients will have radiographic imaging (CT or MRI) every 8 weeks to assess tumor resection. An end of treatment visit for clinical evaluations and safety assessments will be performed approximately 28 days (7 days) after the last dose of study drug. Patients discontinuing study treatment will be followed every 3-6 months for disease recurrence and survival.