Celltrion Inc. announced that the U.S. Food and Drug Administration (FDA) has granted approval for STOBOCLO® (denosumab-bmwo) and OSENVELT® (denosumab-bmwo) as interchangeable biosimilar products to their reference XGEVA® (denosumab) and PROLIA® (denosumab) for all approved indications. This approval became effective on October 29, 2025. This designation allows pharmacists to substitute these biosimilar products for their reference products without prescriber consultation, in accordance with state laws.
The interchangeability approval was supported by clinical evidence from comprehensive Phase III clinical trials in postmenopausal women with osteoporosis. These studies confirmed the equivalence of pharmacodynamics, safety, pharmacokinetics, and efficacy parameters compared to the reference denosumab products.
STOBOCLO® is a receptor activator of NF-kB ligand (RANKL) inhibitor, which is similar to the PROLIA® product. It is approved for the treatment of postmenopausal women and men with osteoporosis at high fracture risk, glucocorticoid-induced osteoporosis, and bone loss associated with hormonal therapies for cancer. It is contraindicated in patients with hypersensitivity to denosumab, during pregnancy, and in those with hypoglycemia. A boxed warning highlights the risk of severe hypocalcemia in individuals with chronic kidney disease-mineral bone disorder (CKD-MBD). The most common adverse effects include back pain and cystitis, as well as musculoskeletal pain.
OSENVELT® is also a RANKL inhibitor that acts via a mechanism similar to XGEVA®. It is approved to prevent skeletal-related events among patients with bone metastases from solid tumors or multiple myeloma. This product is approved to treat giant cell tumors of bone and to manage hypercalcemia of malignancy refractory to bisphosphonate therapy. Warnings include the risk of hypoglycemia, embryo-fetal toxicity, and atypical fractures. The common side effects include edema, diarrhea, fatigue, anemia, nausea, and back pain.
Both products were launched in the U.S. in July 2025. OSENVELT® is supplied as a 70mg/mL formulation, whereas STOBOLCO® is available as a 60 mg/mL formulation. According to recent FDA guidelines, biosimilar developers can now apply for their interchangeability designations based on existing Biologics License Application (BLA) data.
Thomas Nusbickel, Chief Commercial Officer, Celltrion USA, stated that “this decision enhances confidence among healthcare professionals and supports affordable access to therapies for skeletal diseases, while potentially reducing the healthcare expenses.”
Celltrion’s achievement marks a significant milestone in expanding biosimilar availability in the U.S. market. The dual interchangeability status of OSENVELT® STOBOCLO® underscores the company’s leadership in biosimilar commitment to innovation, accessibility, and cost efficiency in the treatment of skeletal and bone disorders.
Reference: Celltrion. U.S. FDA grants interchangeability designation to Celltrion’s denosumab biosimilars, STOBOCLO® (denosumab-bmwo) and OSENVELT® (denosumab-bmwo). Published October 30, 2025. Accessed October 31, 2025. U.S. FDA grants interchangeability designation to Celltrion’s denosumab biosimilars, STOBOCLO® (denosumab-bmwo) and OSENVELT® (denosumab-bmwo) > Press Release | CelltrionUSA
