HSP90AA1 and gastrointestinal stromal tumor: To date, not a single Hsp90 inhibitor has received final approval from the US FDA for treatment of human cancers and targeting Hsp90 chaperones in cancer remains a work in progress2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12 (note: the approval of Hsp90 inhibitor Pimitespib/TAS-116 as an oral, instead of systemic, treatment of reoccurred and late-stage gastrointestinal stromal tumor [GIST] by the Ministry of Health, Labor and Welfare of Japan in 202213 will be specifically discussed in a later section of this article).