Carfilzomib is a tetrapeptide epoxyketone and an analog of epoxomicin, acting as a selective proteasome inhibitor, such as the chymotrypsin-like β5 subunit of the constitutive 20S proteasome (IC50 = 5.2 nM) and the β5i subunit of the immunoproteasome 20Si (LMP7; IC50 = 14 nM). It has been used as an injectable antineoplastic agent (IV only).
https://www.bocsci.com/carfilzomib-cas-868540-17-4-item-305419.html