PACMA 31 is an irreversible, orally active protein disulfide isomerase ( PDI ) inhibitor with an IC 50 of 10 μM. PACMA 31 forms a covalent bond with the active site cysteines of PDI . PACMA 31 shows tumor targeting ability and significantly suppresses ovarian tumor growth without causing toxicity to normal tissues. PACMA 31 is a click chemistry reagent, it contains an Alkyne group and can undergo copper-catalyzed azide-alkyne cycloaddition (CuAAc) with molecules containing Azide groups.