(Reuters) – The U.S. Food and Drug Administration said on Friday it had approved a biosimilar to Roche Holding AG’s blockbuster breast cancer treatment, Herceptin.

The biosimilar, Ontruzant, is sold by Merck Sharp & Dohme Corp, a unit of Merck & Co Inc, and is developed by Samsung Bioepis Co Ltd, which is a joint venture between Samsung BioLogics and Biogen Inc.

The approval https://twitter.com/FDA_Drug_Info/status/1086327386059157504 comes just a few weeks after the health regulator gave Celltrion Inc’s Herzuma – another biosimilar to Herceptin – its nod to market it commercially.

Herceptin, which generated sales of 7.01 billion Swiss francs in 2017, is one of the world’s most successful antibody drugs and has been a mainstay of Roche profits for many years.

Herceptin and other complex medicines called biologics are made from living cells, making them difficult to copy with precision. Their similar versions are called biosimilars, instead of generics.

The FDA had declined to approve Pfizer’s biosimilar of Herceptin in April.

(This story corrects paragraph 2 to say Ontruzant is “sold” by Merck Sharp & Dohme and Corp not “co-developed”. Also removes reference to Merck from headline)

(Reporting by Aakash Jagadeesh Babu in Bengaluru; Editing by Maju Samuel)