---- Evergreening -- Pharma companies exploit strong patent protection by layering new patents onto old drugs

Definition Evergreening, also known as patent “layering” or “life-cycle management,” is a practice by which drug innovators allegedly seek “to prolong their effective periods of patent protection through ... strategies that add new patents to their quivers as old ones expire.”377 As discussed above, because different aspects of pharmaceutical products (and improvements thereon) are patentable,378 dozens of different patents can protect a single pharmaceutical product. The average number of patents per drug has steadily increased since the Hatch-Waxman Act became law in 1984.379 On average, there are about 3 patents listed for each pharmaceutical product listed in the Orange Book. 380 Particularly profitable drugs are usually protected by more patents than average,381 and some of those patents may be added to the Orange Book relatively late in the life cycle of a drug (as opposed to when a new drug has just come to market). Because later-issued patents generally have later expiration dates (presuming they arise from a later patent application), these later patents, if valid, may extend the total effective exclusivity period for a drug or biologic. One comprehensive study of evergreening found that 78% of the drugs that had new patents added to their Orange Book listing were for existing drugs—not new market drugs just coming to market—and that such “evergreening” was particularly common for best-selling drugs.382 For example, a 2020 report from the U.S. House of Representatives Committee on Oversight and Reform investigated the pricing of Revlimid, a top-selling plasma cell myeloma drug made by Celgene Corporation.383 The staff report concluded that Celgene “stifled generic competition by filing for” numerous patents—including ten patents on Revlimid’s REMS program—“and enforcing those patents against potential generic competitors.”384 Another House Committee on Oversight and Reform investigation into Amgen’s biologic Enbrel, used to treat rheumatoid arthritis, concluded that “Amgen has leveraged its patent and lifecycle management strategies to prevent competitors from introducing lower-priced biosimilar versions of Enbrel.”385