CEP-18770

Delanzomib (CEP-18770) is a potent chymotrypsin-like proteasome inhibitor with an IC50 of 3.8 nM. Delanzomib (CEP-18770) prevents the proliferation of several tumor cell lines, such as A2780 ovarian cancer cells, PC3 prostate cancer, H460, LoVo colon cancer, RPMI8226 multiple myeloma cancer and HS-Sultan anaplastic non-Hodgkin lymphoma with IC50 of 13.7, 22.2, 34.2 11.3, 5.6 and 8.2 nM, respectively. The IC50 values of Delanzomib (CEP-18770) are similar to those of bortezomib, with the chymotryptic and caspase-like activities being inhibited at low-nanomolar concentrations. Delanzomib (CEP-18770) blocks the ubiquitin-proteasome pathway in several MM and in the chronic myelogenous leukemia cell line, K562. Delanzomib (CEP-18770) gives rise to an accumulation of ubiquitinated proteins over 4 to 8 hours with a profile similar to that observed after bortezomib treatment.Delanzomib (CEP-18770) completely blocks the degradation of IκBα. Delanzomib (CEP-18770) markedly decreases high levels of NF-κB activity in both RPMI-8226 and U266 cells. The time- and concentration-dependent suppression of NF-kB DNA-binding activity in MM cell lines by Delanzomib (CEP-18770) leads to a decrease of several NF-κB-modulated genes mediating the growth and survival of tumor cells including IkBα itself, the X-chromosome-linked inhibitor-of-apoptosis protein (XIAP), the pro-inflammatory cytokines TNF-α and interleukin-1β (IL-1β), the intracellular adhesion molecule (ICAM1), and the pro-angiogeneic factor vascular endothelial growth factor. The proapoptotic activity of Delanzomib (CEP-18770) against MM is not limited solely to tumor-derived MM cell lines, but extends to primary MM explants from relapsed or refractory patients including those previously treated with bortezomib. In addition, the combination of Delanzomib (CEP-18770) with melphalan or bortezomib generates synergistic prevention of MM cell viability in vitro. Delanzomib (CEP-18770) reveals sustained and dose-related relative tumor weight inhibition. Delanzomib (CEP-18770) leads to dose-related induction of complete tumor regressions, as compared with bortezomib treatment, which results in a 50% incidence of CR at its maximally tolerated dose (MTD) of 1.2 mg/kg intravenously.In contrast to bortezomib, Delanzomib (CEP-18770) reveals dose-related increases in the incidence of tumor-free mice by the completion of these studies (120 days after tumor transplantation). Oral administration of Delanzomib (CEP-18770) yields a marked decrease of tumor weight and notable dose-related incidence of complete tumor regression with minimal changes in animal body weight over the course of 120 day studies. Relative to bortezomib, equiactive doses of Delanzomib (CEP-18770) reveals a greater and more sustained dose-related inhibition of tumor proteasome activity, corresponding temporally with maximum induction of caspase-3 and 7 activity.The maximum apoptotic signal is 2.5 fold greater for Delanzomib (CEP-18770) versus bortezomib.