(Repeats with "UPDATE 3" tag in headline with no changes to text)
* FDA does not ask Coherus for additional trial
* Coherus predicts roughly one-year delay
* Coherus shares tumble 30 pct, Amgen up slightly
By Divya Grover
June 12 (Reuters) - Coherus BioSciences Inc said on Monday the U.S. Food and Drug Administration (FDA) declined to approve its biosimilar copy of Amgen Inc's blockbuster treatment, Neulasta, which is used to fight infections in cancer patients.
Shares of Coherus tumbled 30 percent to $14.47 in morning trading, while Amgen's shares were up slightly at $164.19.
Drug developers including Redwood City, California-based Coherus are racing to make the first biosimilar copy of Neulasta, which generated about $4.6 billion or a fifth of Amgen's sales last year.
Amgen expects biosimilar competition for the drug by the fourth quarter of 2017, it said earlier this year.
The FDA last year declined to approve Novartis AG's copycat for Neulasta, while its decision on Mylan NV and Biocon Ltd's biosimilar is expected by October.
Biotech drugs such as Neulasta are made inside living cells, so it is impossible to make exact generic copies, as is possible with simple pills. As a result, regulators are approving products that are "similar" enough to do the same job.
Developing biosimilars requires considerable expertise and is relatively costly, but investment in the field is growing as many blockbuster biotech medicines start to go off patent.
Coherus on Monday said the FDA had not asked it to conduct another trial on its Neulasta copy, but instead requested a re-analysis of some existing data with a more sensitive assay. An assay is a tool used to detect a marker of disease or risk in a sample taken from a patient.
It would take Coherus up to six months to address the FDA's concerns, and the FDA could take another six months to review the company's submission, Coherus Chief Executive Dennis Lanfear said on a call with analysts.
Amgen earlier this year filed a lawsuit against Coherus alleging that Coherus poached its employees and encouraged them to use Amgen's trade secrets to speed up production of biosimilars. Coherus denies the charge.
Lanfear was previously Amgen's vice president of market development, while Coherus's chief scientific officer once managed Amgen's analytical R&D department.
Amgen won approval for Neulasta in 2002 as a longer-lasting version of its earlier drug, Neupogen. Both drugs are designed to boost infection-fighting white blood cells following chemotherapy.
Coherus, which is developing various biosimilars, has also submitted an application to market its Neulasta copy in Europe. (Reporting by Divya Grover in Bengaluru and Toni Clarke in Washington; Editing by Saumyadeb Chakrabarty and Sai Sachin Ravikumar)