Discovery and optimization of 3-(2-(Pyrazolo[1,5-a]pyrimidin-6-yl)ethynyl)benzamides as novel selective and orally bioavailable discoidin domain receptor 1 (DDR1) inhibitors

J Med Chem. 2013 Apr 25;56(8):3281-95. doi: 10.1021/jm301824k. Epub 2013 Apr 10.


Discoidin domain receptor 1 (DDR1) is an emerging potential molecular target for new anticancer drug discovery. We have discovered a series of 3-(2-(pyrazolo[1,5-a]pyrimidin-6-yl) ethynyl)benzamides that are selective and orally bioavailable DDR1 inhibitors. The two most promising compounds (7rh and 7rj) inhibited the enzymatic activity of DDR1, with IC50 values of 6.8 and 7.0 nM, respectively, but were significantly less potent in suppressing the kinase activities of DDR2, Bcr-Abl, and c-Kit. Further study revealed that 7rh bound with DDR1 with a Kd value of 0.6 nM, while it was significantly less potent to the other 455 kinases tested. The S(35) and S(10) selectivity scores of 7rh were 0.035 and 0.008, respectively. The compounds also potently inhibited the proliferation of cancer cells expressing high levels of DDR1 and strongly suppressed cancer cell invasion, adhesion, and tumorigenicity. Preliminary pharmacokinetic studies suggested that they possessed good PK profiles, with oral bioavailabilities of 67.4% and 56.2%, respectively.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Benzamides / chemical synthesis
  • Benzamides / pharmacokinetics
  • Benzamides / pharmacology*
  • Biological Availability
  • Cell Line, Tumor
  • Discoidin Domain Receptors
  • Fusion Proteins, bcr-abl / antagonists & inhibitors
  • Humans
  • Inhibitory Concentration 50
  • Protein Kinase Inhibitors / chemical synthesis
  • Protein Kinase Inhibitors / pharmacokinetics
  • Protein Kinase Inhibitors / pharmacology*
  • Proto-Oncogene Proteins c-kit / antagonists & inhibitors
  • Pyrimidines / chemical synthesis
  • Pyrimidines / pharmacokinetics
  • Pyrimidines / pharmacology*
  • Receptor Protein-Tyrosine Kinases / antagonists & inhibitors*
  • Receptors, Mitogen / antagonists & inhibitors*


  • Benzamides
  • Protein Kinase Inhibitors
  • Pyrimidines
  • Receptors, Mitogen
  • Discoidin Domain Receptors
  • Proto-Oncogene Proteins c-kit
  • Receptor Protein-Tyrosine Kinases
  • Fusion Proteins, bcr-abl