dBET1

Treatment with dBET1 elicits a comparable, modest effect on MYC and PIM1 expression. Its treatment downregulates MYC and PIM1 transcription, suggestive of secondary transcriptional effects and transcription of BRD4 and BRD3 are unaffected, consistent with post-transcriptional effects. Transcription of BRD2 is affected by dBET1 and protein stability of the BRD2 gene product is influenced by dBET1. dBET1 induces a potent and superior inhibitory effect on MV4;11 cell proliferation at 24 hours (measured by ATP content, IC50 = 0.14 μM). Exposure of primary leukemic patient blasts to dBET1 elicits dose-proportionate depletion of BRD4 and induction of apoptosis^[1]. dBET1-mediated targeted degradation of BET proteins robustly dampens pro-inflammatory responses in LPS-stimulated microglia, that is, depletion of BRD2 and BRD4 with dBET1 is associated with dramatically reduced LPS-induced COX-2 and iNOS protein levels and pro-inflammatory gene transcription of Nos2, Il-1β, Il-6, Tnfα, Ccl2, Ptgs2, and Mmp9^[2].

Immunoblot analysis

Administration of dBET1 attenuates tumor progression and decreases tumor weight assessed post-mortem in murine xenograft model of human MV4;11 leukemia cells. Pharmacokinetic studies of dBET1 (50 mg/kg IP) corroborate adequate drug exposure in vivo (Cmax = 392 nM, Tmax=0.5 hr, terminal t_1/2=6.69 hr, AUC_last=2109 hr*ng/ml, AUC_INF=295 hr*ng/ml). Two weeks of dBET1 is well tolerated by mice without a meaningful effect on weight, white blood count, hematocrit or platelet count^[1].