title: Potent activity of carfilzomib, a novel, irreversible inhibitor of the ubiquitin-proteasome pathway, against preclinical models of multiple myeloma.
abstract: The proteasome has emerged as an important target for cancer therapy with the approval of bortezomib, a first-in-class, reversible proteasome inhibitor, for relapsed/refractory multiple myeloma (MM). However, many patients have disease that does not respond to bortezomib, whereas others develop resistance, suggesting the need for other inhibitors with enhanced activity. We therefore evaluated a novel, irreversible, epoxomicin-related proteasome inhibitor, carfilzomib. In models of MM, this agent potently bound and specifically inhibited the chymotrypsin-like proteasome and immunoproteasome activities, resulting in accumulation of ubiquitinated substrates. Carfilzomib induced a dose- and time-dependent inhibition of proliferation, ultimately leading to apoptosis. Programmed cell death was associated with activation of c-Jun-N-terminal kinase, mitochondrial membrane depolarization, release of cytochrome c, and activation of both intrinsic and extrinsic caspase pathways. This agent also inhibited proliferation and activated apoptosis in patient-derived MM cells and neoplastic cells from patients with other hematologic malignancies. Importantly, carfilzomib showed increased efficacy compared with bortezomib and was active against bortezomib-resistant MM cell lines and samples from patients with clinical bortezomib resistance. Carfilzomib also overcame resistance to other conventional agents and acted synergistically with dexamethasone to enhance cell death. Taken together, these data provide a rationale for the clinical evaluation of carfilzomib in MM.
authors.affiliation: Lineberger Comprehensive Cancer Center and Department of Medicine, Division of Hematology/Oncology, University of North Carolina, Chapel Hill, NC, USA.
authors.forename: Deborah J
authors.initials: DJ
authors.lastname: Kuhn
authors.forename: Qing
authors.initials: Q
authors.lastname: Chen
authors.forename: Peter M
authors.initials: PM
authors.lastname: Voorhees
authors.forename: John S
authors.initials: JS
authors.lastname: Strader
authors.forename: Kevin D
authors.initials: KD
authors.lastname: Shenk
authors.forename: Congcong M
authors.initials: CM
authors.lastname: Sun
authors.forename: Susan D
authors.initials: SD
authors.lastname: Demo
authors.forename: Mark K
authors.initials: MK
authors.lastname: Bennett
authors.forename: Fijs W B
authors.initials: FW
authors.lastname: van Leeuwen
authors.forename: Asher A
authors.initials: AA
authors.lastname: Chanan-Khan
authors.forename: Robert Z
authors.initials: RZ
authors.lastname: Orlowski
mesh_terms: D000970:Antineoplastic Agents / Q000494:pharmacology / Q000627:therapeutic use; D017209:Apoptosis / Q000187:drug effects; D001897:Boronic Acids / Q000494:pharmacology; D000069286:Bortezomib; D049109:Cell Proliferation / Q000187:drug effects; D004353:Drug Evaluation, Preclinical; D019008:Drug Resistance, Neoplasm / Q000187:drug effects; D006801:Humans; D008954:Models, Biological; D009101:Multiple Myeloma / Q000188:drug therapy* / Q000473:pathology*; D009842:Oligopeptides / Q000494:pharmacology* / Q000627:therapeutic use*; D011480:Protease Inhibitors / Q000494:pharmacology / Q000627:therapeutic use; D061988:Proteasome Inhibitors; D011719:Pyrazines / Q000494:pharmacology; D015398:Signal Transduction / Q000187:drug effects; D014407:Tumor Cells, Cultured; D025801:Ubiquitin / Q000037:antagonists & inhibitors / Q000378:metabolism
chemical_list: D000970:Antineoplastic Agents; D001897:Boronic Acids; D009842:Oligopeptides; D011480:Protease Inhibitors; D061988:Proteasome Inhibitors; D011719:Pyrazines; D025801:Ubiquitin; D000069286:Bortezomib; C524865:carfilzomib