AZD5153 6-hydroxy-2-naphthoic acid

Unlike previously described monovalent inhibitors, AZD5153 ligates two bromodomains in BRD4 simultaneously. AZD5153 treatment markedly affects transcriptional programs of MYC, E2F, and mTOR. Of note, mTOR pathway modulation is associated with cell line sensitivity to AZD5153. AZD5153 potently disrupts BRD4 foci in U2OS cells with an IC50 value of 1.7 nmol/L. AZD5153 efficiently downregulates MYC protein levels across the cell line panel irrespective of their sensitivity to AZD5153. AML, MM, and DLBCL cell lines are highly sensitive to AZD5153^[1].

Apoptosis was analyzed by flow cytometry using CellEvent Caspase 3/7 Green detection reagent. MV-4-11, MM.1S, and K562 cells were pretreated with AZD5153 or I-BET762 for 48 hours in culture media. Cells were collected and stained with 5 μmol/L final concentration of CellEvent for 30 minutes at 37°C. Flow cytometry was done on a BD Fortessa using the Blue laser and FITC filter set.

In vivo administration of AZD5153 leads to tumor stasis or regression in multiple xenograft models of acute myeloid leukemia, multiple myeloma, and diffuse large B-cell lymphoma. AZD5153 modulates MYC and HEXIM1 in AML xenograft tumors and human whole blood^[1]. AZD5153 is administered orally to mice bearing MV-4-11 xenografts, and pharmacodynamic activity (intratumoral levels of c-Myc) is measured at 2, 4, and 8 h postdose. A considerable decrease in c-Myc expression is observed out to 8 h post dose at free plasma levels of compound <0.2 μM. This decrease in c-Myc expression after treatment with AZD5153 is consistent with other published BET inhibitors^[2].