ArQule starts dosing in Ph I ARQ 621 trial

US drug developer ArQule has commenced patient dosing in a Phase I trial of ARQ 621, its second-generation, small molecule inhibitor of the Eg5  kinesin motor protein.

In preclinical studies, the agent potently and selectively inhibited Eg5  while sparing other members of the kinesin protein superfamily. Exposure  to ARQ 621 causes apoptosis and cell death in multiple human cancer cell  lines in vitro and in vivo. At efficacious doses in animal studies,  there is no observed evidence of hematological changes and bone marrow  toxicity, the same side effects that have hampered the development of  first-generation Eg5 inhibitors by virtue of limiting dosing  regimens.