By Ben Hirschler

LONDON (Reuters) – Europe has approved a fifth copy of AbbVie’s $18-billion-a-year biologic drug Humira – the world’s best-selling prescription medicine – ramping up competition among makers of less-expensive biotech drugs.

Mylan and Fujifilm Kyowa Kirin Biologics said on Thursday they had won a European Commission green light to market their version of the injectable medicine, known as Hulio. They intend to launch it in Europe on or after Oct. 16, when AbbVie’s primary European patent on Humira expires.

The large number of Humira copies reflects intense rivalry for a slice of a huge market as demand for so-called biosimilars takes off in Europe, where adoption of the cut-price products has been much faster than in the United States.

Europe accounted for around $4.4 billion of Humira’s global sales in the 12 months to June 30, 2018, according healthcare data consultancy IQVIA.

Amgen, Novartis’s generics wing Sandoz, South Korea’s Samsung Bioepis and Germany’s Boehringer Ingelheim have already won approval for four other biosimilars to Humira.

Humira is used to treat a range of conditions including rheumatoid arthritis, Crohn’s disease, ulcerative colitis and psoriasis.

Its commercial success and popularity among patients means it has become a major cost for health systems across Europe, and health administrators say they will waste no time in exploiting the arrival of cheaper biosimilars to drive down bills.

Because injectable biologic drugs such as Humira are made in living cells, they cannot be exact replicas of the original medicine, so regulators have come up with the notion of biosimilars – drugs that are similar enough to do the job.

The conventional wisdom has been that biosimilar uptake would be slow and price discounts modest, since these products are expensive to develop and doctors may be wary about using a medicine that isn’t identical to the original.

But Europe’s recent experience with the first wave of biosimilar antibody drugs – the biggest section of the biologic market – has upended expectations, suggesting AbbVie will face fierce competition.

Still, analysts don’t expect global Humira sales to fall off a cliff just yet, since there are delays in the arrival of biosimilars in the all-important U.S. market.

While expiry of the Humira patent opens the door to biosimilars in Europe, such copies are not expected to launch in the United States until 2023.

(For a graphic on ‘AbbVie’s Humira riding high, for now’ click

(Reporting by Ben Hirschler; editing by Jason Neely and David Stamp)