Discovery of a potent and orally active hedgehog pathway antagonist (IPI-926)

J Med Chem. 2009 Jul 23;52(14):4400-18. doi: 10.1021/jm900305z.


Recent evidence suggests that blocking aberrant hedgehog pathway signaling may be a promising therapeutic strategy for the treatment of several types of cancer. Cyclopamine, a plant Veratrum alkaloid, is a natural product antagonist of the hedgehog pathway. In a previous report, a seven-membered D-ring semisynthetic analogue of cyclopamine, IPI-269609 (2), was shown to have greater acid stability and better aqueous solubility compared to cyclopamine. Further modifications of the A-ring system generated three series of analogues with improved potency and/or solubility. Lead compounds from each series were characterized in vitro and evaluated in vivo for biological activity and pharmacokinetic properties. These studies led to the discovery of IPI-926 (compound 28), a novel semisynthetic cyclopamine analogue with substantially improved pharmaceutical properties and potency and a favorable pharmacokinetic profile relative to cyclopamine and compound 2. As a result, complete tumor regression was observed in a Hh-dependent medulloblastoma allograft model after daily oral administration of 40 mg/kg of compound 28.

MeSH terms

  • Administration, Oral
  • Animals
  • Antineoplastic Agents / administration & dosage
  • Antineoplastic Agents / chemistry
  • Antineoplastic Agents / pharmacokinetics
  • Antineoplastic Agents / pharmacology
  • Cell Line
  • Drug Discovery*
  • Hedgehog Proteins / antagonists & inhibitors*
  • Hedgehog Proteins / metabolism*
  • Humans
  • Liver / cytology
  • Medulloblastoma / drug therapy
  • Medulloblastoma / pathology
  • Microsomes / drug effects
  • Microsomes / metabolism
  • Signal Transduction / drug effects*
  • Stereoisomerism
  • Veratrum Alkaloids / administration & dosage*
  • Veratrum Alkaloids / chemistry
  • Veratrum Alkaloids / pharmacokinetics
  • Veratrum Alkaloids / pharmacology*


  • Antineoplastic Agents
  • Hedgehog Proteins
  • IPI-926
  • Veratrum Alkaloids
  • cyclopamine