Atypical retinoids: An expanding series of anti-leukemia and anti-cancer agents endowed with selective apoptotic activity

Retinoid-related molecules (RRMs) are an interesting class of novel molecules endowed with remarkable and selective apoptotic activity against various leukemia and cancer cell types. ST1926 is the most promising molecule and is active in vivo on numerous experimental models of leukemia and cancer. This has led to the development of a compound that will soon undergo phase I clinical trials. Although the primary molecular targets of RRMs' apoptotic activity are still unknown, ST1926 and congeners are characterized by a peculiar mechanism of action that centers on the mitochondrion and is associated with alterations in the homeostasis of intracellular calcium.