Celltrion, Inc., a leading global biopharmaceutical company, announced that the USA Food and Drug Administration (FDA) has designated Stoboclo (denosumab-bmwo) and Osenvelt (denosumab-bmwo) as interchangeable biosimilars to the reference products Prolia (denosumab) and Xgeva (denosumab), respectively, for all approved indications.

The interchangeability (IC) designation allows Stoboclo and Osenvelt to be substituted at the pharmacy level for their reference biologics without requiring prescriber consultation, in accordance with state pharmacy laws.

“Today’s interchangeability designations reinforce confidence in Stoboclo and Osenvelt among physicians and pharmacists, enabling a more seamless transition from the reference products to our denosumab biosimilars,” said Thomas Nusbickel, Chief Commercial Officer, Celltrion USA. “Building on our strong biosimilar heritage, Celltrion remains dedicated to delivering affordable, high-quality treatment options for patients with skeletal diseases, while creating opportunities for significant healthcare savings.”

The FDA’s decision was based on comprehensive analytical and clinical data, including results from Phase III clinical trials in postmenopausal women with osteoporosis. These studies evaluated the efficacy, pharmacodynamics (PD), pharmacokinetics (PK), safety, and immunogenicity of Celltrion’s denosumab biosimilars compared to their reference products.

Both products were launched in the USA market in July 2025 — Stoboclo is available as a 60 mg/mL injection, while Osenvelt is supplied as a 120 mg/1.7 mL (70 mg/mL) injection.

Recent FDA draft guidance allows biosimilar applicants to request interchangeability designations using existing data from their Biologics License Application (BLA), marking a shift from previous requirements that demanded additional switching studies.