CO-101 is designed to improve uptake of gemcitabine in patients with low hENT1 expression.

Ventana Medical Systems is to develop a companion diagnostic for use in ongoing clinical trials of Clovis Oncology’s lead anticancer candidate, Phase II-stage CO-101. The human equilibrative nucleoside transporter 1 (hENT1) immunohistochemistry assay will be leveraged to identify patients with low level tumor expression of the hENT1 protein. Clovis says that if CO-101 development is successful and submitted for registration in major markets, Ventana will also submit the hENT1 assay for PMA as a Class III device.

CO-101 is a lipid-conjugated form of gemcitabine in development initially as a treatment for pancreatic cancer. Clovis licensed the product from Clavis Pharma ( in November 2009. The deal included a $15 million up-front payment and could bring Clavis another $365 million in development, regulatory, and sales milestones as well as tiered double-digit sales royalties.

Clovis estimates that up to two-thirds of pancreatic cancer patients have limited cellular uptake of gemcitabine due to deficient expression of hENT1. CO-101 was designed to improve the efficacy of gemcitabine by enabling the drug to enter cancer cells without requiring uptake by its specific transporter molecule.

An ongoing international Phase II trial is comparing CO-101 with gemcitabine therapy in some 250 newly diagnosed patients with advanced pancreatic cancer. Expression of hENT1 in tumor tissue will be measured during the trial, and patients will be categorized into hENT1-high or hENT1-low groups prior to final analysis. In addition to evaluating overall patient survival, study results will be analyzed in relation to levels of hENT1 expressed by individual  patients’ tumors.  The emphasis will be on comparative overall survival in participants with low levels of tumor hENT1 expression. Data from the trial is expected in the first half of 2012.

Clovis is also evaluating potential development opportunities of CO-101 in additional indications including relapse refractory pancreatic adenocarcinoma and other solid tumors. The drug has been granted orphan drug status for the treatment of pancreatic cancer in the EU and the U.S.

Clovis is an oncology company founded by former executives of Pharmion, which was acquired by Celgene in 2008 for $2.9 billion. Clovis raised $146 million in start-up financing during May 2009.

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