Gilead Sciences is planning to close its Durham, North Carolina office by the end of the year, laying off 150 employees, the Triangle Business Journal reports. About 20 percent of the employees were offered relocation packages, said company spokesperson Amy Flood.

"This comes after a lengthy review," Flood said. "We will be consolidating our R&D activities in our Foster City, [California] headquarters."

The Durham closure leaves Gilead with no presence in North Carolina.

Gilead is a bioscience company that conducts anti-viral research and development. The Durham office conducted hepatitis B and C clinical research.