Amgen Inc. will lay off up to 121 workers at its California sites beginning Dec. 31, according to a notice filed in early November with the California Employment Development Department. The multinational biopharmaceutical company – which makes drugs to treat cancer, cardiovascular and inflammatory conditions – expects to cut as many as 200 jobs across its research and development division, with the bulk of the cuts taking place in Thousand Oaks and San Francisco, according to Amgen spokeswoman Kristen Davis. “Given the dynamic nature of our business and the need to ensure greater flexibility across our organization, we must continue to be increasingly efficient in our operational discipline and invest our resources in a way that ensures our continued scientific leadership,” Davis told the Business Journal in an e-mailed statement. “The organizational changes are designed to support those efforts.” Amgen did not break down the number of employees that it anticipates will lose their jobs at its individual California sites. The company does predict that the total number of affected employees in Thousand Oaks will be less than initially expected as workers apply to other positions within the company. Some of the jobs affected by the staff reduction in Thousand Oaks will be relocated to Amgen’s other sites, according to the company’s notice with the employment department. Amgen reported the layoffs to the employment department on Nov. 1. On Tuesday, shares of Amgen (AMGN) fell 85 cents, or about half a percent, to close at $170.13 on the Nasdaq.