Oprozomib (ONX 0912) is an orally bioavailable inhibitor for CT-L activity of 20S proteasome β5/LMP7 with IC50 of 36 nM/82 nM. 

The anti-MM activity of Oprozomib is associated with activation of caspase-8, caspase-9, caspase-3, and PARP, as well as inhibition of migration of MM cells and angiogenesis. Oprozomib is demonstrated an absolute bioavailability of up to 39% in rodents and dogs. It is well tolerated with repeated oral administration at doses resulting in >80% proteasome inhibition in most tissues and elicited an antitumor response in multiple human tumor xenograft and mouse syngeneic models.