Amgen Inc. plans to lay off 70 workers at its Thousand Oaks headquarters, mostly in information technology jobs. The pharmaceutical company announced the cuts in an email, specifying that the positions are predominantly in the information systems department with a small number elsewhere. “The majority of the positions were eliminated due to recently outsourced work,” spokeswoman Kristen Davis said in the email released Thursday. “Each of the individuals notified was offered comprehensive severance benefits that provide cash, health insurance and career transition services.” The company employs about 6,000 people at its Thousand Oaks campus. This round of layoffs is the second this year for Amgen. In March, the company announced 252 job cuts in sales and operations. Shares closed up 8 cents, or a fraction of 1 percent, at $117.82 on the Nasdaq.