Hopes Dashed For Biosimilar Enbrel?

Not a happy start, we think, to the Thanksgiving break for the likes of biosimilar hopefuls Merck & Co., Celltrion, Teva and Hospira. Late on Nov. 22, Amgen declared, in a thoughtfully-timed, rather succinct missive, that the patent life on RA and psoriasis blockbuster Enbrel (etanercept) had just been extended by 17 years.

Enbrel had been widely touted as one of the first complex biological likely to appear in biosimilar form, with protection assumed to expire in late 2012 in the U.S., and three years later in Europe. It was going to mark the start of the real returns for biosimilars, after their lackluster first round. Now it may be that the frontrunner copycats' race may have been futile.

Ok, so we're not patent lawyers. But U.S. patent 8,063,182, issued to Roche (and via exclusive license to Amgen), “describes and claims the fusion protein that is etanercept, and by statute, the ‘182 patent has a term of 17 years from today.” It looks pretty real to us, and composition of matter patents (which is what this is) are usually stronger than the kinds of formulation and process patents that had apparently been defending the drug to date.

Merck in June 2011 signed a deal committing it to pay up to $720 million for Korean Hanwha’s Phase III copy of the fusion protein (up-front money wasn’t revealed, nor whether this patent was factored in, so we won't get too hung up on numbers. But let's just say it has been an expensive week for Merck). It was one of the “eight to ten” compounds in Merck’s biosimilars pipeline that BioVentures chief Mike Kamarck has been particularly excited about.

Merck doesn’t feel it’s appropriate at the moment to share its feeling towards ‘182.

Others do. “This is HUGE,” declared one senior lawyer who has followed biosimilars for many years. And although the new U.S FDA 351 (k) pathway for biosimilar drugs in theory allows for patent litigation to begin, and thus potentially be resolved, early (e.g. before the product is launched), it also has some serious drawbacks that make it unclear how widely it will be used. (Kamarck, however, has said that Merck plans to use 351 (k).)

Perhaps Merck has anticipated and figured its way around this patent; after all, it was filed back in 1995. And even if not, '182 needn’t stop Enbrel competitors, such as Abbott’s Humira, Roche’s Rituxan or J&J’s Simponi from facing generics. Nor need it stop generic Enbrel in Europe.

Either way, any resulting litigation from the unexpected issuing of ‘182 could provide a meaty test for the dispute-resolution provisions in the new FDA biosimilar pathway.