• The U.S. FDA approved STOBOCLO^® (denosumab-bmwo) and OSENVELT^® (denosumab-bmwo) as interchangeable with the reference products PROLIA^® (denosumab) and XGEVA^® (denosumab), respectively, for all approved indications, effective as of October 29, 2025
• The interchangeability (IC) designations of STOBOCLO and OSENVELT were granted based not only on the comparative clinical data – including pharmacokinetics, efficacy, safety and an immunogenicity study in postmenopausal women with osteoporosis^[1] - but also on analytical data demonstrating similarity of STOBOCLO and OSENVELT versus the reference product
• The IC designations enhance patient access and provider choice in the treatment of osteoporosis-related fracture as well as cancer-related bone loss

Celltrion, Inc.announced that the U.S. 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 is a regulatory designation granted by the FDA, which means STOBOCLO and OSENVELT may now be substituted at the pharmacy for the reference products without consulting the prescriber, subject to state laws.^[2]

"Today's IC designations reinforce confidence in STOBOCLO and OSENVELT among physicians and pharmacists, facilitating a more seamless switch from the reference products to our denosumab biosimilars," said Thomas Nusbickel, Chief Commercial Officer at Celltrion USA. "Building on our strong heritage in biosimilars, Celltrion remains committed to offering more affordable and much-needed treatment options to patients living with skeletal diseases, creating greater potential to deliver savings to patients and the U.S. healthcare system."

The interchangeability designations of STOBOCLO and OSENVELT were based on the comprehensive evidence including the clinical results from Phase III clinical trials in postmenopausal women with osteoporosis designed to evaluate the efficacy, pharmacodynamics (PD), pharmacokinetics (PK), safety and immunogenicity of denosumab biosimilar to its reference product. ^[1]

STOBOCLO and OSENVELT were introduced in the U.S. market in July 2025. STOBOCLO is currently available in 60 mg/mL injection and OSENVELT is offered in 120 mg/1.7 mL (70 mg/mL) injection.

According to recent FDA draft guidance, biosimilar applicants can request an interchangeability designation using existing data from their Biologics License Application (BLA). Previously, the FDA granted this status only to biosimilars that submitted multiple switch studies meeting additional data criteria.