BERKELEY, Calif., September 3, 2008--(Business Wire)--Plexxikon Inc. today announced that it has initiated a Phase 1 human clinical trial for PLX5568, a novel kinase inhibitor targeted for the treatment of at least two major indications with unmet medical needs: pain as well as polycystic kidney disease (PKD). PLX5568 has demonstrated robust preclinical efficacy in multiple pain models, including neuropathic pain as well as acute and inflammatory pain. In addition, PLX5568 has demonstrated compelling efficacy in multiple preclinical models of PKD.