A rare bit of good news for the beleaguered biotech, which is laying off employees, grappling with lower Medicare reimbursement and responding to government probes. A federal jury in Boston decided that a key patent on its best-selling Arnaesp and Epogen anemia meds is valid, which means Roche may be prevented from selling its own version. Called Mircera, Roche’s drug is due to receive FDA approval next month.

Earlier this month, William Burns, who heads Roche’s pharma business, told analysts on a conference call that the Swiss drugmaker wouldn’t attempt to launch Mircera in the US if Amgen were to win the trial, Reuters reminds us. UPDATE: However, a Roche spokeswoman says the drugmakers is “evaluating…legal options, including the possibility of an appeal.”

“The verdict is disappointing because in the end, it is US patients with chronic kidney disease who lose,” Burns says in a statement. “Amgen has had an extended monopoly for the last 20 years in the U.S. blocking new therapeutic options to treat anaemia from being introduced.”

UPDATE: Wall Street seems to think Roche is finished. “We consider this to be a key victory for Amgen, which has successfully defended its EPO patent estate for the third time against yet another formidable competitor,” writes Michael King of Rodman & Renshaw in an investor note this afternoon. “Roche has indicated its intent to appeal the decision; however, we would suggest it will likely be a year or more before a decision, if any, is made on the merits of Roche’s appeal.”

Amgen sued Roche two years ago to prevent competition in the lucrative US makret. Last year, Amgen’s two drugs had combined sales of $6.6 billion, roughly 46 percent of Amgen’s revenue. The trial, which was closely watched, included sensational statements by an Amgen sales director to a doctor to avoid the upcoming Roche drug, leaving the doctor to wonder if he’d visited by the mob.