Gilead Sciences, Inc. announced that the US Patent & Trademark Office (PTO) has completed the first of four re-examination proceedings and has confirmed the patentability of US Patent No. 6,043,230, which covers a method of use for Viread (tenofovir disoproxil fumarate). The US PTO has not announced its ruling on the remaining three Viread patents under review.

The four US PTO review proceedings were initiated July 2007 in response to a challenge issued by the Public Patent Foundation (PUBPAT) in March 2007 for US Patents No. 5,922,695; 5,977,089; 5,935,946; and 6,043,230. In its request for the re-examinations, PUBPAT claimed that prior art existed that would have impacted the issuance of the original patents.

Upon completion of the first re-examination proceeding, the US PTO has confirmed the patentability of US Patent No. 6,043,230 with no reduction in the scope of the claims.

"We are pleased that the US PTO, following a detailed and comprehensive analysis, has concluded this first re-examination," said Gregg Alton, senior vice president and general counsel. "We have always believed that the US PTO would recognize that Viread is a novel product, and we remain confident that the office will rule similarly on the remaining three patents under review."

Gilead Sciences is a biopharmaceutical company that discovers, develops and commercializes innovative therapeutics in areas of unmet medical need. The company's mission is to advance the care of patients suffering from life-threatening diseases worldwide.