On 14 November 2025, Amgen filed BPCIA proceedings in the US District Court for the District of New Jersey against Alkem Laboratories and its subsidiaries, Ascend Laboratories and Enzene Biosciences, alleging infringement of 35 US patents covering denosumab, pharmaceutical compositions of denosumab, methods of manufacturing therapeutic proteins like denosumab, and denosumab products.
According to Amgen’s complaint, the litigation arises out of a submission to the FDA of a Biologics License Application in relation to Alkem/Ascend’s biosimilars to Amgen’s Prolia® and Xgeva® (denosumab).
The filing of the new complaint means Amgen currently has five US proceedings pending regarding denosumab biosimilars, including lawsuits against Hikma/Gedeon Richter and Shanghai Henlius/Organon, commenced on 25 June 2025, and against Alvotech/Dr Reddy’s and Amneal/mAbxience, commenced on 6 November 2025. Amgen has settled a further six US proceedings relating to denosumab biosimilars with:
- Sandoz: proceedings commenced in May 2023, were resolved in April 2024, with Sandoz launching its denosumab biosimilars, Jubbonti® and Wyost®, in June 2025;
- Fresenius Kabi: proceedings commenced in October 2024 were resolved by a global settlement, resulting in the launch of Fresenius’ Conexxence® and Bomyntra® in early July 2025;
- Celltrion: US proceedings settled in January 2025, with Celltrion launching Stoboclo® and Osenvelt® in July 2025;
- Accord and Intas: US litigation with Amgen settled in July 2025, permitting launch of Accord/Intas’ denosumab biosimilar from 1 October 2025;
- Samsung Bioepis settled in early September 2025, with the terms of that settlement, including launch dates for Samsung Bioepis’ denosumab biosimilars, remaining confidential; and
- Biocon: US proceedings commenced on 30 June 2025 were settled shortly thereafter, permitting Biocon’s 1 October 2025 launch of Bosaya™ and Aukelso™.
Earlier in November 2025, the European Medicine Agency’s CHMP adopted a positive opinion for Enzene/Theramex’s Osqay®, biosimilar to Amgen’s Prolia® (denosumab). Enzene and Theramex entered into an agreement in 2021 under which Enzene will supply Theramex with its denosumab biosimilar for commercialisation in Europe, the UK, Switzerland and Australia.