Crystal structure of ARQ 531 in complex with the kinase domain of BTK

Experimental Data Snapshot

  • Resolution: 1.15 Å
  • R-Value Free: 0.150 
  • R-Value Work: 0.131 

wwPDB Validation   3D Report Full Report

Ligand Structure Quality Assessment 

This is version 1.3 of the entry. See complete history


The BTK Inhibitor ARQ 531 Targets Ibrutinib-Resistant CLL and Richter Transformation.

Reiff, S.D.Mantel, R.Smith, L.L.Greene, J.T.Muhowski, E.M.Fabian, C.A.Goettl, V.M.Tran, M.Harrington, B.K.Rogers, K.A.Awan, F.T.Maddocks, K.Andritsos, L.Lehman, A.M.Sampath, D.Lapalombella, R.Eathiraj, S.Abbadessa, G.Schwartz, B.Johnson, A.J.Byrd, J.C.Woyach, J.A.

(2018) Cancer Discov 8: 1300-1315

  • DOI: https://doi.org/10.1158/2159-8290.CD-17-1409
  • Primary Citation of Related Structures:  

  • PubMed Abstract: 

    Targeted inhibition of Bruton tyrosine kinase (BTK) with the irreversible inhibitor ibrutinib has improved outcomes for patients with hematologic malignancies, including chronic lymphocytic leukemia (CLL). Here, we describe preclinical investigations of ARQ 531, a potent, reversible inhibitor of BTK with additional activity against Src family kinases and kinases related to ERK signaling. We hypothesized that targeting additional kinases would improve global inhibition of signaling pathways, producing more robust responses. In vitro treatment of patient CLL cells with ARQ 531 decreases BTK-mediated functions including B-cell receptor (BCR) signaling, viability, migration, CD40 and CD86 expression, and NF-κB gene transcription. In vivo , ARQ 531 was found to increase survival over ibrutinib in a murine Eμ-TCL1 engraftment model of CLL and a murine Eμ-MYC/TCL1 engraftment model resembling Richter transformation. Additionally, ARQ 531 inhibits CLL cell survival and suppresses BCR-mediated activation of C481S BTK and PLCγ2 mutants, which facilitate clinical resistance to ibrutinib. Significance: This study characterizes a rationally designed kinase inhibitor with efficacy in models recapitulating the most common mechanisms of acquired resistance to ibrutinib. Reversible BTK inhibition is a promising strategy to combat progressive CLL, and multikinase inhibition demonstrates superior efficacy to targeted ibrutinib therapy in the setting of Richter transformation. Cancer Discov; 8(10); 1300-15. ©2018 AACR. This article is highlighted in the In This Issue feature, p. 1195 .

  • Organizational Affiliation

    Department of Internal Medicine, Division of Hematology, Comprehensive Cancer Center, The Ohio State University, Columbus, Ohio.

Find similar proteins by:  (by identity cutoff)  |  3D Structure
Entity ID: 1
MoleculeChains Sequence LengthOrganismDetailsImage
Tyrosine-protein kinase BTK290Homo sapiensMutation(s): 0 
UniProt & NIH Common Fund Data Resources
Find proteins for Q06187 (Homo sapiens)
Explore Q06187 
Go to UniProtKB:  Q06187
PHAROS:  Q06187
GTEx:  ENSG00000010671 
Entity Groups  
Sequence Clusters30% Identity50% Identity70% Identity90% Identity95% Identity100% Identity
UniProt GroupQ06187
Sequence Annotations
  • Reference Sequence
Small Molecules
Binding Affinity Annotations 
IDSourceBinding Affinity
HRA Binding MOAD:  6E4F IC50: 0.85 (nM) from 1 assay(s)
Experimental Data & Validation

Experimental Data

  • Resolution: 1.15 Å
  • R-Value Free: 0.150 
  • R-Value Work: 0.131 
  • Space Group: P 21 21 2
Unit Cell:
Length ( Å )Angle ( ˚ )
a = 72.485α = 90
b = 104.422β = 90
c = 38.089γ = 90
Software Package:
Software NamePurpose
XDSdata reduction
Aimlessdata scaling
PDB_EXTRACTdata extraction

Structure Validation

View Full Validation Report

Ligand Structure Quality Assessment 

Entry History 

Deposition Data

  • Released Date: 2018-09-05 
  • Deposition Author(s): Eathiraj, S.

Revision History  (Full details and data files)

  • Version 1.0: 2018-09-05
    Type: Initial release
  • Version 1.1: 2018-10-03
    Changes: Data collection, Database references
  • Version 1.2: 2018-10-10
    Changes: Data collection, Database references, Structure summary
  • Version 1.3: 2024-03-13
    Changes: Data collection, Database references, Structure summary