Kinesin inhibitor marches toward first-in-class pivotal trial

The key to treating cancer is to put a stop to the out-of-control cell growth that leads to tumor formation. One way to do this is to go after the microtubules that help coordinate this rampant cell division. Yet because microtubules function in both dividing and non-dividing cells—for example, in non-dividing neurons they’re involved in intracellular transport—drugs that target microtubules directly tend to cause nerve pain and other side effects. That’s why researchers have been on the lookout for more specific targets in the microtubule machinery—ones that are only active in rapidly growing cells during mitosis.

The kinesin spindle protein (KSP), a molecular motor that crawls along the microtubules to help the cells divide, provides one such candidate target. To date, drugs designed to block this protein (which is also known as Eg5) have failed to live up to their potential, with something of a KSP inhibitor graveyard littered with failed and abandoned products from companies including Cytokinetics, AstraZeneca, Eli Lilly and others. Read more in Nature Medicine.