SAN DIEGO, CA., April 3, 2002 — Gen-Probe Incorporated announced today that the United States Court of Appeals for the Federal Circuit has affirmed a lower court decision dismissing a patent infringement lawsuit brought against it in 1999 by Enzo Biochem, Inc. The suit claimed that Gen-Probe's products for the detection of Neisseria gonorrhoeae infringed U.S. patent 4,900,659. The suit also named Chugai Pharmaceutical Co., Ltd., Chugai Pharma, U.S.A., bioMerieux, Inc., bioMerieux SA and Becton-Dickinson and Co. as defendants. The lower court decision, announced January 24, 2001 by Judge Alvin Hellerstein in the United States District Court for the Southern District of New York, granted the defendants' motion for a summary judgment that all of the claims in the Enzo patent are invalid. The Appeals Court affirmed Judge Hellerstein's ruling that Enzo had failed to adequately describe its claimed inventions in writing as required by the patent laws.

Henry L. Nordhoff, president and chief executive officer of Gen-Probe said, "The Appeals Court ruling confirms Gen-Probe's long-held position that Enzo's patent is invalid. We are pleased that we were able to win this case on summary judgment and avoid the substantial burden of having to go to trial to disprove Enzo's claims. While Enzo has the right to request a rehearing or to seek an appeal of the decision to the Supreme Court, we are confident that today's decision is consistent with the law and will be upheld."

Gen-Probe Incorporated, a San Diego-based company, is a recognized world leader in the development, manufacture and commercialization of diagnostic products based on its patented genetic probe technologies. The company has received 40 FDA clearances for genetic probe tests to detect a wide range of microorganisms, including those causing sexually transmitted diseases, tuberculosis, strep throat, pneumonia and fungal infections. Gen-Probe recently received FDA approval of its amplified viral nucleic acid tests for screening the blood supply for HIV-1 and hepatitis C viruses. These tests are currently used to screen over 70% of blood donations in the United States. Gen-Probe recently launched its new amplified Aptima™ Combo 2 test for the detection of Chlamydia infections and gonorrhea.

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