On 6 November 2025, Amgen filed two separate BPCIA litigation suits in the US District Court for the District of New Jersey, against each of Dr Reddy’s/Alvotech and Amneal/mAbxience, asserting infringement of 31 US patents covering denosumab, pharmaceutical compositions of denosumab, methods of manufacturing therapeutic proteins like denosumab, and denosumab products.
The litigation follows the FDA’s March 2025 acceptance for review of both Alvotech/Dr Reddy’s Biologics Licence Application (BLA) for AVT03 and Amneal/mAbxience’s BLA for its denosumab biosimilars (MB09).
Under a partnership announced in October 2023, Amneal/mAbxience’s denosumab biosimilars are being developed and manufactured by mAbxience, with Amneal pursuing regulatory approval and having exclusive US commercialisation rights. In May 2024, Dr Reddy’s and Alvotech entered into a licence and supply agreement for the commercialisation of AVT03, under which Alvotech develops and manufactures the product and Dr Reddy’s will commercialise it exclusively in the US, and semi-exclusively in the EU and UK.
The filing of the two new complaints means Amgen currently has four US proceedings pending regarding denosumab biosimilars, including lawsuits against Hikma/Gedeon Richter and Shanghai Henlius/Organon, commenced on 25 June 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™.