Protein Target(s) Name: BET proteins BRD4, BRD3, BRD2

Mechanism of Action: PROTAC degrader

Description: VH032 (VHL) based and IBET-726 based PROTAC that degrades BET proteins in cells. MZP-55 exhibits preferential degradation of BRD3 and BRD4 at nM concentrations over BRD2 (1). 

Chemical Name: (2S,4R)-1-((S)-1-(4-((2S,4R)-1-acetyl-4-((4-chlorophenyl)amino)-2-methyl-1,2,3,4-tetrahydroquinolin-6-yl)phenyl)-18-(tert-butyl)-1,16-dioxo-5,8,11,14-tetraoxa-2,17-diazanonadecan-19-oyl)-4-hydroxy-N-(4-(4-methylthiazol-5-yl)benzyl)pyrrolidine-2-carboxamide

CAS Number: 2010159-48-3

In vitro pharmacology*: MZP-55 reduces BET protein levels in human cells: Brd4 pDC50 | Dmax (%) in HeLa cells (24 h) = 8.1 | 95; Brd3 pDC50 | Dmax (%) in HeLa cells (24 h) = 7.7 | 92
MZP-55 shows antiproliferative and Myc-suppression activity in AML MV4;11 and HL60 cells: pEC50 in MV4;11 | HL-60 cells (48 h) = 7.1 | 6.4
Data from ref. (1)

*DC50: concentration in molar causing 50% reduction of protein level relative to vehicle control treatment.
Dmax: maximum reduction of protein level relative to vehicle control treatment.
EC50: effective concentration in molar causing 50% reduction of cell viability relative to vehicle control treatment. 

Biophysical binding data: Binary Kd (Brd4-BD2) = 8 nM; Binary Kd (VHL) = 110 nM; Ternary Kd (VHL, in the presence of Brd4-BD2) = 180 nM; cooperativity (alpha) = 0.6
Data from ref. (1)
Ternary complex VHL:MZP-55:Brd4-BD2 t1/2 (SPR) = 1 s. Data from ref. (2

In vivo PK data: not available

Crystal Structure: not available

Negative control: not available


Primary References: 

  1. Chan et al. (2018) Impact of Target Warhead and Linkage Vector on Inducing Protein Degradation: Comparison of Bromodomain and Extra-Terminal (BET) Degraders Derived From Triazolodiazepine (JQ1) and Tetrahydroquinoline (I-BET726) BET Inhibitor Scaffolds. J. Med. Chem. 61, 504.  DOI: 10.1021/acs.jmedchem.6b01912; PMID: 28595007
  2. Roy et al. (2019) SPR-Measured Dissociation Kinetics of PROTAC Ternary Complexes Influence Target Degradation Rate. ACS Chem. Biol. 14, 361. DOI: 10.1021/acschembio.9b00092; PMID: 30721025


Articles that have used MZP-55:

  1. 2018 Chan J Med Chem
  2. 2019 Roy ACS Chem Biol
  3. 2020 Klein ACS Med Chem Lett
  4. 2021 Castro RSC Med Chem
  5. 2021 Weng J Med Chem


More information on our chemical probes can be found from the Chemical Probes portal, and from commercial vendors such as Tocris Bio-Techne.