Secondary patents prove to be key in biosimilar blocking strategies, researchers find
While the US biosimilars industry has generally been a disappointment since its inception, with FDA approving 33 biosimilars since 2015, just a fraction of those have immediately followed their approvals with launches. And more than a handful of biosimilars for two of the biggest blockbusters of all time — AbbVie’s Humira and Amgen’s Enbrel — remain approved by FDA but still have not launched because of legal settlements.
Part of the reason that many of these brand-name biologic companies have proven successful at blocking biosimilar competition is through their use of patent fortresses, designed to make it impossible, or extremely expensive, to wage legal battle.
In 2018, for example, AbbVie’s Humira was covered by 132 patents, Roche’s Avastin (which now has biosimilar competition) was covered by 86 patents and Herceptin (which also now has biosimilar competition) by 108 patents.
Researchers are now uncovering the extent to which secondary patents (i.e., not the ones covering the active ingredient) have played a major role in stunting the growth of the biosimilars industry.
“Among patents asserted in US biosimilar litigation, only 6% covered the active ingredient in the biologic drug, while the vast majority covered uses or peripheral features of the drug, such as its manufacturing processes or delivery devices. The median time of patent filing was more than a decade after approval of the originator biologic, and one-fifth of the patents had no equivalents — either patents or patent applications — in the European Union, Canada or Japan,” researchers at Harvard Medical School and the Cumming School of Medicine at the University of Calgary wrote in a new Nature Biotechnology investigation.
While noting that secondary patents filed a median of more than a decade after a biologic’s approval “were predominantly involved in the litigation affecting the market entry of biosimilars for nine key biologic drugs,” they also said their findings underscore concerns about the weaknesses of the US patent system, adding:
Although patenting standards are similar across jurisdictions, their application by US patent examiners can be less stringent, a trend that has been attributed to suboptimal resource allocation among other reasons. For example, three examiners evaluate a patent application in the European Union compared to one in the United States. Patent examiners in the United States also process more than double the number of patents or claims annually than European Patent Office examiners. While our study found that many secondary patents are at issue in biosimilar efforts to enter the US market, another study found the main hurdle to market entry of biosimilars for 9 top-selling monoclonal antibodies in Europe was the key patent on the originator product, not secondary patents.
But some who track the biosimilar industry closely don’t have nearly as ominous of an outlook as others, some of whom think biosimilars should just be scrapped for biologic price controls after a certain cut-off date.

Bernstein analyst Ronny Gal said in a note last summer that while the US market has been stagnant recently, he predicted it will return to growth as new molecules launch, with biosimilars to Lucentis and Humira coming in the next 12 months.
“If this sounds to some of you like the generic market circa 2005, we tend to agree,” he wrote. “Further, we suspect this was not lost on some of some of the early winners in the biosimilar market. They seem to be beginning to pursue next-stage strategies, e.g. Novartis going to mid-size biosimilars, Coherus entry to follow-on PD1, Pfizer and Amgen launching late-entrant biosimilars at prices above the market. There is another decade of growth here (the generics peaked in 2015) but the days of just developing the largest five drugs and being successful because competitors made mistakes are probably reaching their end.”