Gen-Probe Incorporated has submitted to the US Food and Drug Administration (FDA) a supplemental regulatory application for the additional use of the Procleix Ultrio assay to screen donated blood for the hepatitis B virus (HBV). The FDA approved the assay to screen donated blood for HIV-1 and the hepatitis C virus (HCV) in late 2006.

The company is seeking approval to use the assay to screen for HBV on both its semi-automated instrument platform and on the fully automated, high-throughput TIGRIS system.

"Demonstrating that our Procleix Ultrio assay is able to identify HBV-infected blood donations that serological tests miss and submitting this supplemental Biologics License Application (BLA) to the FDA are major milestones for our blood screening business, and may further safeguard the US donated blood supply," said Hank Nordhoff, chairman and chief executive officer, Gen-Probe.

Gen-Probe's blood screening products are marketed worldwide by Chiron, a business unit of Novartis Vaccines and Diagnostics, Inc.

In October of 2006, the FDA approved the Procleix Ultrio assay to screen donated blood, plasma, organs and tissue for HIV-1 and HCV on Gen-Probe's semi-automated instrument system. In May 2007, the FDA granted a similar approval to use the assay on the TIGRIS system.

However, the Procleix Ultrio assay was not approved to screen donated blood for HBV, as the initial pivotal study for the assay was not designed to, and did not, demonstrate HBV yield. Yield is defined as HBV-infected blood donations that were intercepted by the Procleix Ultrio 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 and Chiron agreed to conduct a post-marketing study of the Procleix Ultrio assay to demonstrate the HBV yield required for a donor-screening claim.

Gen-Probe began this post-marketing study in early 2007. To date, approximately 500,000 blood donations have been screened in the study, and two HBV yield cases have been identified. Data on these two yield cases comprise the foundation of the Company's supplemental BLA.

HBV is the most common serious liver infection in the world and is transmitted through contact with blood and body fluids. HBV infection can lead to liver failure, cirrhosis or cancer. According to the World Health Organization, more than 350 million people worldwide are chronically infected with HBV. More than one million people die annually as a result of HBV infections.

Gen-Probe Incorporated is a global leader in the development, manufacture and marketing of rapid, accurate and cost-effective nucleic acid tests (NATs) that are used primarily to diagnose human diseases and screen donated human blood.