(Adds details on Herceptin, background)
April 23 (Reuters) - Pfizer Inc said on Monday U.S. regulators declined to approve the company's biosimilar of Roche's blockbuster treatment for breast cancer, Herceptin, and sought additional technical information.
The company said the requested information did not relate to safety or clinical data submitted in the application.
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.
Herceptin, which generated sales of 7.01 billion Swiss francs ($7.18 billion) in 2017, is one of the world's most successful antibody drugs and has been a mainstay of Roche profits for many years.
FDA in December approved Mylan's biosimilar of Herceptin. ($1 = 0.9758 Swiss francs) (Reporting by Akankshita Mukhopadhyay in Bengaluru; Editing by Anil D'Silva and Sriraj Kalluvila)