ANPEP and plasma cell myeloma: This compound, considered a pro-drug activated by aminopeptidases expressed in multiple myelomas (such as APN, leucyl aminopeptidase 3 (LAP3), arginyl aminopeptidase (RNPEP), and leukotriene A4 hydrolase (LTA4H) [58,155]) has been studied in phase I/II (HORIZON, ANCHOR) [156,157] and phase III (OCEAN) [157,158] trials [57,58].