The skin irritating principle from Thapsia garganica was isolated, named thapsigargin and the structure
elucidated. By inhibiting the sarco/endoplasmic reticulum Ca2+ ATPase (SERCA) thapsigargin provokes
apoptosis in almost all cells. By conjugating thapsigargin to peptides, which are only substrates for either
prostate specific antigen (PSA) or prostate specific membrane antigen (PSMA) prodrugs were created,
which selectively affect prostate cancer cells or neovascular tissue in tumors. One of the prodrug is
currently tested in clinical phase II. The prodrug under clinical trial has been named mipsagargin.