pimitespib pimitespib pimitespib (trade name jeselhy) is a drug for the treatment of gastrointestinal stromal tumors. it was discovered and developed by taiho pharmaceutical co. the mechanism of action of pimitespib involves inhibition of heat shock protein 90 (hsp90). pimitespibclinical datatrade namesjeselhyother namestas 116legal statuslegal status rx in japan identifierscas number1260533-36-5uniiplo044mudzkeggd11920chemical and physical dataformulac25h26n8omolar mass454.538 g·mol−13d model (jsmol)interactive image smiles o=c(n)c1=cc=c(c(=c1)cc)n2n=c(c=3c2=nc=cc3n4c=nc(=c4)c=5c=nn(c5)c)c(c)c in june 2022, it received approval in japan for gastrointestinal stromal tumors that have progressed after chemotherapy.