U.S. patent officials on Thursday denied petitions by Amgen to review two formulation patents on AbbVie's Humira, a potential setback in Amgen efforts to market a biosimilar version of the world's top-selling prescription medicine.
In June, Amgen, the world's biggest biotechnology company, asked the U.S. Patent and Trademark Office for the review, arguing that the patents in question should not have been granted in the first place for Humira, an injected rheumatoid arthritis treatment with annual sales approaching $14 billion.
In declining to review the patents, the agency said "we determine, based on the petition and the accompanying evidence, that Amgen has not shown a reasonable likelihood of prevailing on any of its challenges."
Amgen said it still plans to challenge the legality of the patents.
"Although we are disappointed by the PTO's decision, we continue to question the validity of the patents," the company said in a statement. "We look forward to presenting our position in court."
Amgen in November became the first company to file with U.S. health regulators seeking approval to sell a less expensive biosimilar version of the blockbuster medicine. Several companies are also developing biosimilar versions of Humira.
Amgen has said it expects the first of its several biosimilars in development to reach the market between 2017 and 2019.
AbbVie this week said it sees Humira sales reaching $18 billion by 2020. Based on its various patents, AbbVie said it does not expect competition from biosimilars until 2022.
Unlike chemical medicines, biotech drugs are made from living cells so exact copies are not possible, thus the term biosimilar rather than generic as with copies of pills.
Amgen shares closed up 5.3 percent at $153.16, while AbbVie shares rose 6.6 percent to close at $54.56. Shares of both companies were virtually unchanged in extended trading.
(Additional reporting by Andrew Chung; Editing by David Gregorio and James Dalgleish)