Delanzomib, also known as CEP-18770, is An orally bioavailable synthetic P2 threonine boronic acid inhibitor of the chymotrypsin-like activity of the proteasome, with potential antineoplastic activity. Proteasome inhibitor CEP 18770 represses the proteasomal degradation of a variety of proteins, including inhibitory kappaBalpha (IkappaBalpha), resulting in the cytoplasmic sequestration of the transcription factor NF-kappaB; inhibition of NF-kappaB nuclear translocation and transcriptional up-regulation of a variety of cell growth-promoting factors; and apoptotic cell death in susceptible tumor cell populations.