Assay Screens Blood and Tissues for HBV

In October 2006 the U.S. Food and Drug Administration (FDA) granted marketing approval for the Gen-Probe (San Diego, CA, USA) Procleix Ultrio assay to run on the company's semi-automated instrument system. The assay was approved to screen donated blood, plasma, organs, and tissue for HIV-1 and hepatitis C virus (HCV) in individual blood donations or in pools of up to 16 blood samples, and to detect the presence of hepatitis B virus (HBV).

However, the Procleix Ultrio assay was not approved to screen donated blood for HBV, as the initial study for the assay was not designed to, and did not, demonstrate yield. Yield is defined as HBV-infected blood donations that were intercepted by the assay, but that were initially negative based on serology tests for HBV surface antigen and core antibodies. Based on discussions with the FDA, Gen-Probe agreed to conduct a post-marketing study of the Procleix Ultrio assay to demonstrate the HBV yield required for a donor-screening claim.

We are pleased that we continue to make positive regulatory progress toward fully commercializing our Procleix Ultrio assay on the Tigris system in the United States, said Henry L. Nordhoff, Gen-Probe's chairman, president and CEO. Our goal is to offer customers the capability to intercept three dangerous viruses at once in donated blood, using a fully automated, high-throughput system that maximizes the efficiency of testing and minimizes the potential for human error. The Procleix Tigris system can process 1,000 blood samples in about 14 hours, a level of productivity that facilitates testing in smaller pool sizes, which in turn increases assay sensitivity and increases blood safety.

The FDA has recently given Gen-Probe feedback on the draft design of this post-marketing study. The duration of the study will depend on the rate at which HBV yield is identified. Based on the outcome of the study, the company intends to submit a regulatory application to the FDA seeking a donor-screening claim for HBV for the Procleix Ultrio assay. As a result, Gen-Probe believes it is likely to earn a US$10 million milestone from Chiron (Dublin, Ireland), the company's blood screening partner, in 2008. This milestone is due upon full approval of the Procleix Ultrio assay on the Tigris system in the United States.

Outside the United States, where the Procleix Ultrio assay has been approved since early 2004, blood bank customers have routinely intercepted HBV-infected donations that otherwise would have been transfused into blood recipients. Recent scientific reports from Europe have documented yield rates as high as approximately one in 50,000 individual donations, a much higher rate than is observed with either HIV-1 or HCV.

In addition, many US blood screening customers use the Procleix Tigris system to test for the West Nile virus (WNV) under an investigational new drug application. Gen-Probe's regulatory application to test for WNV on the Procleix Tigris system is under review by the FDA.



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