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Clin Cancer Res. 2011 May 1;17(9):2799-806. doi: 10.1158/1078-0432.CCR-10-2580. Epub 2011 Mar 9.

MK-1775, a potent Wee1 inhibitor, synergizes with gemcitabine to achieve tumor regressions, selectively in p53-deficient pancreatic cancer xenografts.

Author information

  • 1Department of Oncology, Johns Hopkins University School of Medicine, Baltimore, Maryland, USA. rnv1@jhmi.edu

Abstract

PURPOSE:

Investigate the efficacy and pharmacodynamic effects of MK-1775, a potent Wee1 inhibitor, in both monotherapy and in combination with gemcitabine (GEM) using a panel of p53-deficient and p53 wild-type human pancreatic cancer xenografts.

EXPERIMENTAL DESIGN:

Nine individual patient-derived pancreatic cancer xenografts (6 with p53-deficient and 3 with p53 wild-type status) from the PancXenoBank collection at Johns Hopkins were treated with MK-1775, GEM, or GEM followed 24 hour later by MK-1775, for 4 weeks. Tumor growth rate/regressions were calculated on day 28. Target modulation was assessed by Western blotting and immunohistochemistry.

RESULTS:

MK-1775 treatment led to the inhibition of Wee1 kinase and reduced inhibitory phosphorylation of its substrate Cdc2. MK-1775, when dosed with GEM, abrogated the checkpoint arrest to promote mitotic entry and facilitated tumor cell death as compared to control and GEM-treated tumors. MK-1775 monotherapy did not induce tumor regressions. However, the combination of GEM with MK-1775 produced robust antitumor activity and remarkably enhanced tumor regression response (4.01-fold) compared to GEM treatment in p53-deficient tumors. Tumor regrowth curves plotted after the drug treatment period suggest that the effect of the combination therapy is longer-lasting than that of GEM. None of the agents produced tumor regressions in p53 wild-type xenografts.

CONCLUSIONS:

These results indicate that MK-1775 selectively synergizes with GEM to achieve tumor regressions, selectively in p53-deficient pancreatic cancer xenografts.

©2011 AACR.

PMID:
21389100
[PubMed - indexed for MEDLINE]
PMCID:
PMC3307341
Free PMC Article
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