Targeting the Isoprenoid Biosynthetic Pathway in Multiple Myeloma.

Multiple myeloma (MM) is a plasma cell malignancy for which there is currently no cure. While treatment options for MM have expanded over the last two decades, all patients will eventually become resistant to current therapies. Thus, there is an urgent need for novel therapeutic strategies to treat MM. The isoprenoid biosynthetic pathway (IBP) is responsible for the post-translational modification of proteins belonging to the Ras small GTPase superfamily, such as Ras, Rho and Rab family members. Given the important roles these GTPase proteins play in various cellular processes, there is significant interest in the development of inhibitors that disturb their prenylation and consequently their activity in MM cells. Numerous preclinical studies have demonstrated that IBP inhibitors have anti-MM effects, including the induction of apoptosis in MM cells and inhibition of osteoclast activity. Some IBP inhibitors have made their way into the clinic. For instance, nitrogenous bisphosphonates are routinely prescribed for the management MM bone disease. Other IBP inhibitors, including statins and farnesyltransferase inhibitors, have been evaluated in clinical trials for MM, while there is substantial preclinical investigation into geranylgeranyl diphosphate synthase inhibitors. Here we discuss recent advances in the development of IBP inhibitors, assess their mechanism of action and evaluate their potential as anti-MM agents.