Merck & Co is said to be planning a job cull involving around 120 employees at recently-acquired Cubist Pharmaceuticals.

The cuts are being made at Cubist’s drug discovery site in Lexington, Massachusetts, and reportedly represent around 20% of its workforce in the state.

Merck closed its $9.5-billion acquisition of Cubist earlier this year. Lainie Keller, director of global communications at the firm, told the Boston Business Journal that the "difficult decision" on the layoffs was prompted by a review of its assets.

All of Cubist's experimental antibiotics in clinical trials will continue to be developed, she told the paper, and noted that some in the preclinical stage will be developed at other sites.