Moreover, the O6-methylguanine-DNA methyltransferase (MGMT) promoter methylation markedly prevalent in SDH-deficient GISTs has represented some proof of concept about the potential role of alkylating agents in this subset of GISTs [50], whereas a phase II trial on temozolomide in advanced SDH-GISTs is still ongoing (NCT03556384); a prolonged disease stability after 18 consecutive cycles of temozolomide has been recently reported in a female metastatic and progressive SDH-deficient GIST 45. Here, SDHB is linked to gastrointestinal stromal tumor.