339 POSTER Identification of XL413, a selective Cdc7 kinase inhibitor which induces cell cycle arrest and exhibits potent antitumor activity

Cdc7 overexpression is an independent prognostic marker and a potential therapeutic target in colorectal cancer

Background

Cdc7 is a widely expressed protein kinase implicated in cell division, cell cycle checkpoint mechanisms and cancer progression. Recently, it has been suggested as a target for anti-cancer therapy.

Methods

To determine the relationship of Cdc7 protein expression with tumor phenotype, molecular features and prognosis, 1800 colorectal carcinomas were analyzed by immunohistochemistry on a tissue microarray.

Results

Cdc7 expression was considered negative in 33.6 %, weak in 57.2 % and strong in 9.2 % of 1711 interpretable CRCs. Loss of Cdc7 expression was significantly associated with high tumor stage (p < 0.0001) and high tumor grade (p = 0.0077), but was unrelated to the nodal status (p = 0.5957). Moreover, a link between Cdc7 expression and the tubular histological tumor type was seen (p < 0.0001). p53 and Cdc7 expression were significantly linked to each other (p = 0.0013). In a multivariate survival analysis, strong Cdc7 expression of CRC was an independent marker of improved patient survival (p = 0.0031).

Conclusion

Our data show that Cdc7 is highly expressed in CRC and a potential therapeutic target in a subset of cancers with high p53 expression. Moreover, our findings strongly argue for a clinical utility of Cdc7 immunostaining as an independent prognostic biomarker in colorectal cancer enabling to select patients for adjuvant treatment.

Targeting cell division cycle 7 kinase: a new approach for cancer therapy

The cell division cycle 7 (Cdc7) is a serine-threonine kinase, originally discovered in budding yeast, required to initiate DNA replication. Human Cdc7 phosphorylates the minichromosome maintenance protein 2 (Mcm2), a component of the DNA replicative helicase needed for genome duplication. Inhibition of Cdc7 in cancer cells impairs progression through S phase, inducing a p53-independent apoptotic cell death, whereas in normal cells, it does not affect cell viability. Small molecule compounds able to interfere with Cdc7 activity have been identified and shown to be effective in controlling tumor growth in animal models. Two Cdc7 inhibitors are currently in phase I clinical development. Inhibition of Cdc7 kinase activity in cancer cells restricts DNA replication and induces apoptotic cell death by an unprecedented molecular mechanism of action.

Cell division cycle 7 kinase inhibitors: 1H-pyrrolo[2,3-b]pyridines, synthesis and structure-activity relationships

Cdc7 kinase has recently emerged as an attractive target for cancer therapy and low-molecular-weight inhibitors of Cdc7 kinase have been found to be effective in the inhibition of tumor growth in animal models. In this paper, we describe synthesis and structure-activity relationships of new 1H-pyrrolo[2,3-b]pyridine derivatives identified as inhibitors of Cdc7 kinase. Progress from (Z)-2-phenyl-5-(1H-pyrrolo[2,3-b]pyridin-3-ylmethylene)-3,5-dihydro-4H-imidazol-4-one (1) to [(Z)-2-(benzylamino)-5-(1H-pyrrolo[2,3-b]pyridin-3-ylmethylene)-1,3-thiazol-4(5H)-one] (42), a potent ATP mimetic inhibitor of Cdc7 kinase with IC(50) value of 7 nM, is also reported.