West Virginia College of Law professor S. Sean Tu published new scholarship in the New England Journal of Medicine. The article is titled "Clearing Dense Drug-Patent Thickets ". Professor Tu's co-authors are: Bernard Chao, University of Denver Sturm College of Law; Ryan Whalen, University of Hong Kong; and Aaron S. Kesselheim, Brigham and Women’s Hospital. The article was published online by the journal on November 27, 2024 and subsequently in print on December 12, 2024.
From the abstract:
Brand-name drug firms often maintain market exclusivity by creating large patent thickets that generic and biosimilar firms must challenge before reaching the market. By delaying market entry, these patent thickets can limit patient access to medications and drive-up health care costs. Drug thickets are typically comprised of follow-on innovation based on a special type of patent (continuation patent) that does not disclose any new information. Continuation patents frequently encounter obviousness-type double patenting (OTDP) rejections during patent examinations, which rejects a patent because it is an obvious variation of a previous patent. To overcome this rejection, patentees file a “terminal disclaimer,” which links the patents so that they will expire at the same time.
Both Congress and the United States Patent and Trademark Office (USPTO) are acutely aware of this problem and have recently proposed solutions to address patents thickets that include secondary patents linked by OTDP rejections and terminal disclaimers. On May 10, 2024, the USPTO proposed a new rule to prevent thickets on the front end by invalidating all patents in a thicket if any one of those patents is invalidated. Accordingly, all patents in a thicket would rise and fall together when linked by a terminal disclaimer. By contrast, a bi-partisan Congressional bill introduced on January 12, 2024, focuses on reducing the back-end harm caused by thickets in patent litigation. The bill would reduce the litigation costs of defending against multiple patents by permitting patentees to enforce only one patent per group connected by terminal disclaimers.
This study reviews how these two reforms would affect Humira’s notoriously large biologic drug patent thicket. We find that the PTO rule could reduce Humira’s patent thicket by as much as 43% while the Congressional bill would allow enforcement of only 24 of Humira’s 105 litigated patents. Similarly, we find that the PTO rule could reduce Revlimid’s small-molecule drug patent thicket by as much as 70% while Congressional bill would allow enforcement of only 12 of Revlimid’s 30 patents listed in the Orange Book.
Find more of Professor Tu's scholarship on SSRN.