Apotex must face a Roche Holding lawsuit claiming its generic version of Valcyte, which treats a virus that afflicts transplant patients and people with AIDS, infringes a Roche patent that expires in 2015.
U.S. District Judge Jeffrey White in San Francisco on Monday denied Apotex's request for a ruling in its favor without trial, according to a court filing. Roche Holding's South San Francisco-based Genentech unit alleged the generic would infringe its patents because the product is, at least in part, in crystalline form.
Apotex said tests performed by Genentech showing evidence of crystallinity were suspect and that the amount of crystalline product is so small it doesn't constitute infringement.
White said he couldn't conclude the testing was invalid and that the results raise a factual question that should be decided by a jury.
Elie Betito, a spokesman for Apotex, didn't immediately comment on the ruling.
Apotex, based in Toronto, told Genentech in 2011 that it had applied for approval from the U.S. Food and Drug Administration to make a generic of Valcyte, according to the complaint.
Genentech said the plan to market the generic will cause "massive infringement" of its patent covering the drug.
The company seeks a court order declaring that the Apotex generic is a patent-infringing drug, blocking the FDA from approving it until Genentech's patent expires in 2015 and barring Apotex from engaging in commercial activity that would infringe the Genentech patent.