Amgen’s stock price continued to rise after...

Amgen’s stock price continued to rise after the Newbury Park biotechnology company received a patent this week for its process for making recombinant erythropoietin, a protein that stimulates production of red blood cells. Amgen’s stock rose $2.50 a share Thursday to $22.75 in over-the-counter trading, adding to a $2.88-a-share increase on Wednesday, the day the patent was announced. Analysts have estimated potential annual sales for erythropoietin at $300 million. Amgen also filed two patent infringement lawsuits this week in federal court in Massachussetts against three companies developing erythropoietin.