It was only one interview to secure the job. I was interviewed by two senior staffs. The interviewed consisted of behavioral questions combined with a bit knowledge of project management experience. There are some case studies but it's not a big deal since it seemed they just want to test our logical thinking. One thing for sure: they scrutinized your resume and kept digging the information on that. Don't forget to learn about Amgen and its recent news in advance as it would make you stand out compare to other candidates.