Kinesin spindle protein (KSP) inhibitors. 9. Discovery of (2S)-4-(2,5-difluorophenyl)-n-[(3R,4S)-3-fluoro-1-methylpiperidin-4-yl]-2-(hydroxymethyl)-N-methyl-2-phenyl-2,5-dihydro-1H-pyrrole-1-carboxamide (MK-0731) for the treatment of taxane-refractory cancer

J Med Chem. 2008 Jul 24;51(14):4239-52. doi: 10.1021/jm800386y. Epub 2008 Jun 25.


Inhibition of kinesin spindle protein (KSP) is a novel mechanism for treatment of cancer with the potential to overcome limitations associated with currently employed cytotoxic agents. Herein, we describe a C2-hydroxymethyl dihydropyrrole KSP inhibitor ( 11) that circumvents hERG channel binding and poor in vivo potency, issues that limited earlier compounds from our program. However, introduction of the C2-hydroxymethyl group caused 11 to be a substrate for cellular efflux by P-glycoprotein (Pgp). Utilizing knowledge garnered from previous KSP inhibitors, we found that beta-fluorination modulated the p K a of the piperidine nitrogen and reduced Pgp efflux, but the resulting compound ( 14) generated a toxic metabolite in vivo. Incorporation of fluorine in a strategic, metabolically benign position by synthesis of an N-methyl-3-fluoro-4-(aminomethyl)piperidine urea led to compound 30 that has an optimal in vitro and metabolic profile. Compound 30 (MK-0731) was recently studied in a phase I clinical trial in patients with taxane-refractory solid tumors.

MeSH terms

  • ATP Binding Cassette Transporter, Subfamily B, Member 1 / metabolism
  • Antineoplastic Agents / pharmacology*
  • Antineoplastic Agents / therapeutic use
  • Enzyme Inhibitors / pharmacology*
  • Enzyme Inhibitors / therapeutic use
  • Humans
  • Kinesin / antagonists & inhibitors*
  • Neoplasms / drug therapy
  • Neoplasms / enzymology*
  • Piperidines / pharmacology*
  • Pyrroles / pharmacology*
  • Taxoids / pharmacology*
  • Taxoids / therapeutic use


  • 4-(2,5-difluorophenyl)-N-(3-fluoro-1-methylpiperidin-4-yl)-2-(hydroxymethyl)-N-methyl-2-phenyl-2,5-dihydro-1H-pyrrole-1-carboxamide
  • ATP Binding Cassette Transporter, Subfamily B, Member 1
  • Antineoplastic Agents
  • Enzyme Inhibitors
  • KIF11 protein, human
  • Piperidines
  • Pyrroles
  • Taxoids
  • Kinesin