Purpose Investigate the efficacy and pharmacodynamic effects of MK-1775, a potent Wee1 inhibitor, in both monotherapy and in combination with gemcitabine using a panel of p53-deficient and p53-wild type human pancreatic cancer xenografts. Experimental design Nine individual patient-derived pancreatic cancer xenografts (six with p53-deficient and three with p53-wild type status) from the PancXenoBank collection at Johns Hopkins were treated with MK-1775, gemcitabine or gemcitabine followed 24 h later by MK-1775 for 4 weeks. Tumor growth rate/regressions were calculated on day 28. Target modulation was assessed by western blot and IHC. Results MK-1775 treatment led to the inhibition of Wee1 kinase and reduced inhibitory phosphorylation of its substrate Cdc2. MK-1775, when dosed with gemcitabine, abrogated the checkpoint arrest to promote mitotic entry and facilitated tumor cell death as compared to control and gemcitabine treated tumors. MK-1775 monotherapy did not induce tumor regressions. However, the combination of gemcitabine with MK-1775 produced robust anti-tumor activity and remarkably enhanced tumor regression response (4.01 fold) compared to gemcitabine treatment in p53-deficient tumors. Tumor re-growth curves plotted after the drug treatment period suggest that the effect of the combination therapy is longer-lasting than that of gemcitabine. None of the agents produced tumor regressions in p53-wild type xenografts. Conclusions These results indicate that MK-1775 selectively synergizes with gemcitabine to achieve tumor regressions, selectively in p53-deficient pancreatic cancer xenografts.

Curcumin or diferuloylmethane is a yellow polyphenol extracted from the rhizome of turmeric (Curcuma longa). A large volume (several hundreds) of published reports has established the anticancer and chemopreventative properties of curcumin in preclinical models of every known major cancer type. Nevertheless, the clinical translation of curcumin has been significantly hampered due to its poor systemic bioavailability, which mandates that patients consume up to 8 to 10 g of the free drug orally each day to achieve detectable levels in circulation. We have engineered a polymeric nanoparticle encapsulated curcumin formulation (NanoCurc) that shows remarkably higher systemic bioavailability in plasma and tissues compared with free curcumin upon parenteral administration. In xenograft models of human pancreatic cancer established in athymic mice, administration of parenteral NanoCurc significantly inhibits primary tumor growth in both subcutaneous and orthotopic settings. The combination of parenteral NanoCurc with gemcitabine results in enhanced tumor growth inhibition versus either single agent, suggesting an additive therapeutic influence in vivo. Furthermore, this combination completely abrogates systemic metastases in orthotopic pancreatic cancer xenograft models. Tumor growth inhibition is accompanied by significant reduction in activation of nuclear factor-κB, as well as significant reduction in expression of matrix metalloproteinase-9 and cyclin D1, in xenografts treated with NanoCurc and gemcitabine. NanoCurc is a promising new formulation that is able to overcome a major impediment for the clinical translation of curcumin to cancer patients by improving systemic bioavailability, and by extension, therapeutic efficacy. Mol Cancer Ther; 9(8); 2255-64. ©2010 AACR.

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