CPI-203 is a potent, selectivie and competitive small molecule inhibitor of BET bromodomain with a mean GI50 value of 0.23μM in MCL cell lines [1].
As an inhibitor of BET proteins, CPI-203 inhibits BRD4 in vitro and in cells. It inhibits the specific Ser2 phosphorylation of both endogenous BRD4 and exogenous mutant BRD4 (BRD4 FEE-AAA) in vivo, thus blocking the recruitment of BRD4 to chromatin. CPI-203 is shown to suppress cell growth of 9 MCL cell lines. And in REC-1 cells, treatment of CPI-203 causes the effects of IRF4 expression. CPI-203 marginally activates the apoptotic program in these cells. The CPI-203-lenalidomide combination is reported to be a promising strategy in MCL cases refractory to proteasome inhibition [1, 2].
References:
[1] Moros A, Rodríguez V, Saborit-Villarroya I, Montraveta A, Balsas P, Sandy P, Martínez A, Wiestner A, Normant E, Campo E, Pérez-Galán P, Colomer D, Roué G. Synergistic antitumor activity of lenalidomide with the BET bromodomain inhibitor CPI203 in bortezomib-resistant mantle cell lymphoma. Leukemia. 2014 Mar 18.
[2] Devaiah BN, Lewis BA, Cherman N, Hewitt MC, Albrecht BK, Robey PG, Ozato K, Sims RJ 3rd, Singer DS. BRD4 is an atypical kinase that phosphorylates serine2 of the RNA polymerase II carboxy-terminal domain. Proc Natl Acad Sci U S A. 2012 May 1;109(18):6927-32.