Coherus BioSciences Inc said on Monday the U.S. Food and Drug Administration (FDA) denied the approval of its biosimilar for Amgen Inc's blockbuster treatment, Neulasta, which fights infections in cancer patients.
Coherus' shares fell nearly 25 percent to $15.50 in trading before the bell.
The biosimilar, CHS-1701, is among Redwood City, California-based Coherus' lead experimental drugs.
The FDA's response comes as Amgen gears up for biosimilar competition for Neulasta, which generated about $4.6 billion in sales last year.
Biosimilars aim to copy biologic products, which are made inside living cells, but they can never be exact duplicates, so biosimilar manufacturers need to conduct clinical trials to show their products work as intended.
The FDA requested Coherus for a re-analysis of certain data and asked the drug developer for more manufacturing information, Coherus said, adding that it would work with the agency to address the concerns.
Amgen's shares were up about 1 percent at $165.75 in premarket trading.
(Reporting by Divya Grover in Bengaluru; Editing by Saumyadeb Chakrabarty and Sai Sachin Ravikumar)