Discovery and canine preclinical assessment of a nontoxic procaspase-3-activating compound

Quinn P. Peterson, Danny C. Hsu, Chris J. Novotny, Diana C. West, Dewey Kim, Joanna M. Schmit, Levent Dirikolu, Paul J. Hergenrother, Timothy M. Fan

Research output: Contribution to journalArticlepeer-review

47 Scopus citations


A critical event in the apoptotic cascade is the proteolytic activation of procaspases to active caspases. The caspase autoactivating compound PAC-1 induces cancer cell apoptosis and exhibits antitumor activity in murine xenograft models when administered orally as a lipid-based formulation or implanted s.c. as a cholesterol pellet. However, high doses of PAC-1 were found to induce neurotoxicity, prompting us to design and assess a novel PAC-1 derivative called S-PAC-1. Similar to PAC-1, S-PAC-1 activated procaspase-3 and induced cancer cell apoptosis. However, S-PAC-1 did not induce neurotoxicity in mice or dogs. Continuous i.v. infusion of S-PAC-1 in dogs led to a steady-state plasma concentration of ∼10 μmol/L for 24 to 72 hours. In a small efficacy trial of S-PAC-1, evaluation of six pet dogs with lymphoma revealed that S-PAC-1 was well tolerated and that the treatments induced partial tumor regression or stable disease in four of six subjects. Our results support this canine setting for further evaluation of small-molecule procaspase-3 activators, including S-PAC-1, a compound that is an excellent candidate for further clinical evaluation as a novel cancer chemotherapeutic.

Original languageEnglish (US)
Pages (from-to)7232-7241
Number of pages10
JournalCancer research
Issue number18
StatePublished - Sep 15 2010

ASJC Scopus subject areas

  • Oncology
  • Cancer Research


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