Amgen Expands Patent Litigation Against Denosumab Biosimilar Developers in Latest BPCIA Filings
Key Insights
Amgen filed three new BPCIA lawsuits in November 2025 against multiple companies developing biosimilars of its blockbuster denosumab products Prolia® and Xgeva®.
The litigation targets Dr. Reddy's/Alvotech's AVT03, Amneal's MB09, and Alkem's ENZ215 biosimilars, asserting 31-35 patents per case covering manufacturing and composition claims.
These cases represent Amgen's eighth through tenth denosumab biosimilar litigations, with five previous cases having settled and several others ongoing.
Amgen Inc. has intensified its patent protection strategy for denosumab by filing three new Biologics Price Competition and Innovation Act (BPCIA) lawsuits in November 2025, targeting multiple companies developing biosimilar versions of its osteoporosis (search) and cancer (search) bone treatment drugs Prolia® and Xgeva®.
Latest Legal Actions Target Multiple Biosimilar Developers
On November 6, 2025, Amgen filed two cases in the U.S. District Court for the District of New Jersey: one against Dr. Reddy's Laboratories and Alvotech regarding their AVT03 biosimilar, and another against Amneal Pharmaceuticals and its partners regarding the MB09 biosimilar. Eight days later, on November 14, 2025, Amgen filed a third case against Alkem Laboratories, Ascend Laboratories (search), and Enzene Biosciences (search) concerning their proposed ENZ215 biosimilar.
The FDA had previously accepted the biologics license applications (BLAs) for these competing products, with Amneal's MB09 accepted on March 12, 2025, and Dr. Reddy's/Alvotech's AVT03 accepted on March 18, 2025. The acceptance date for Alkem's ENZ215 was not disclosed.
Extensive Patent Portfolio Assertions
The lawsuits demonstrate Amgen's comprehensive patent strategy, with the company asserting 31 patents against both Dr. Reddy's/Alvotech and Amneal, and 35 patents against Alkem. The patent portfolios largely overlap across cases, covering 29-31 manufacturing patents, four composition of matter patents, and additional composition and host cell patents in each case.
Notably, one patent, U.S. Patent No. 9,320,816, was asserted for the first time against Amneal, while the remaining patents have been previously litigated in other denosumab biosimilar cases.
Manufacturing Process Disclosure Disputes
Beyond patent infringement claims, Amgen alleges that defendants in both the Dr. Reddy's/Alvotech and Amneal cases failed to comply with BPCIA requirements under § 262(l)(2)(A) by not adequately disclosing manufacturing process information. This procedural violation claim adds another layer to the legal disputes.
Broader Litigation Landscape
These three new cases bring Amgen's total denosumab biosimilar litigations to ten, following previous lawsuits against Sandoz, Celltrion, Samsung Bioepis/Samsung Biologics, Fresenius, Accord Biopharma, Hikma (search) Pharmaceuticals, Shanghai Henlius Biotech, and Biocon Biologics. Of the earlier cases, five have reached settlements, while litigation against Gedeon Richter/Hikma, Henlius/Organon, and Accord/Intas remains ongoing.
Market Context and Commercial Stakes
The aggressive litigation strategy reflects the substantial commercial value of Amgen's denosumab franchise. The company reported FY24 U.S. sales of $2.885 billion for Prolia® and $1.507 billion for Xgeva®, totaling $4.392 billion in combined revenue.
Despite the ongoing patent disputes, biosimilar competition has already begun entering the market. In October 2025, the FDA approved Gedeon Richter/Hikma (search)'s Enoby (search)™/Xtrenbo (search)™ (denosumab-qbde) as the seventh approved Prolia®/Xgeva® biosimilar.
Therapeutic Significance
Denosumab functions as a RANK ligand (search) (RANKL (search)) inhibitor, playing a crucial role in reducing bone fracture risk and skeletal-related events in patients with osteoporosis (search) or cancer (search). The drug's mechanism targets the bone remodeling pathway, making it an important therapeutic option for managing bone health in vulnerable patient populations.
In each lawsuit, Amgen seeks judgment of infringement, permanent injunctions preventing future infringement until patent expiration, damages for post-verdict infringement, and attorney fees, indicating the company's commitment to defending its intellectual property position in this lucrative therapeutic area.