FDA-Approved Denosumab Biosimilars Expand Oncology Options in US

Celltrion USA has announced the US commercial launch of denosumab-bmwo (Stoboclo) and denosumab-bmwo (Osenvelt), biosimilars referencing denosumab (Prolia and Xgeva). These 2 products are among the first wave of denosumab biosimilars to enter the US market.¹

Both biosimilars received FDA approval in March 2025 for all the indications of their reference products. Stoboclo is approved for several forms of osteoporosis and bone loss, while Osenvelt is indicated for the prevention of skeletal-related events (SREs) in patients with cancer, including those with bone metastases or multiple myeloma.

Results from a phase 3 trial (NCT04757376) evaluating efficacy, pharmacodynamics (PD), pharmacokinetics (PK), safety, and immunogenicity for Stoboclo provided the basis for this approval.²

“We are proud to introduce our denosumab biosimilars to the US market, offering patients and healthcare professionals a valuable alternative treatment option,” said Thomas Nusbickel, chief commercial officer at Celltrion USA, in a press release.¹ "Building on our strong heritage in biosimilars, Celltrion remains committed to being a trusted partner for both patients and physicians, while contributing to the overall sustainability of healthcare systems."

Stoboclo (60 mg/mL injection) is a RANKL inhibitor with proven bioequivalence to Prolia. The drug is indicated for postmenopausal women with osteoporosis at high risk for fracture, men with osteoporosis at high risk for fracture, men and women on glucocorticoid therapy at high risk for fracture, men receiving androgen deprivation therapy for nonmetastatic prostate cancer, and women receiving aromatase inhibitors for breast cancer who are at high risk for fracture.

Osenvelt (120 mg/1.7 mL injection) is a denosumab biosimilar referencing Xgeva and is indicated for the management of skeletal complications associated with cancer. It is approved for the prevention of skeletal-related events in patients with multiple myeloma, the treatment of bone metastases from solid tumors, the management of giant cell tumor of bone in adults and skeletally mature adolescents where surgery is not feasible, and the treatment of hypercalcemia of malignancy refractory to bisphosphonates.

Denosumab’s unique mechanism targets the RANKL-RANK interaction, which plays a central role in osteoclast activation and bone resorption. By interrupting this process, Osenvelt helps reduce the incidence of debilitating skeletal complications in cancer patients.

Clinicians must monitor for hypocalcemia, osteonecrosis of the jaw, and femoral fractures. A specific warning notes the potential for clinically significant hypercalcemia following discontinuation, especially in pediatric and growing adolescent populations with giant cell tumors of bone. Oncology providers should develop a discontinuation plan that includes close monitoring and calcium/vitamin D management.

Osenvelt also carries a warning for embryo-fetal toxicity, and pregnancy status should be verified prior to treatment initiation. Effective contraception is recommended during treatment and for 5 months following the last dose.

Integrating Biosimilars Into Practice

Stoboclo and Osenvelt are supported by Celltrion’s patient support services, including Celltrion CONNECT and the Celltrion CARES co-pay assistance program. These services aim to facilitate treatment adherence, affordability, and patient education, particularly for those facing financial or insurance barriers.

By offering cost-effective alternatives without compromising therapeutic quality, Celltrion’s biosimilars may help improve access to essential therapies across multiple disciplines, including oncology, endocrinology, and rheumatology.

For oncologists treating patients with bone metastases, multiple myeloma, or hypercalcemia of malignancy, Osenvelt provides a new biosimilar option that may reduce cost burdens and ensure continuity of care. Similarly, Stoboclo enables more patients with osteoporosis to access a proven therapy through potentially lower-cost treatment channels.

REFERENCES:

1. Celltrion USA announces U.S. launch of denosumab biosimilars, STOBOCLO® and OSENVELT® (denosumab-bmwo). News release. Celltrion USA. July 7, 2025. Accessed July 10, 2025. https://tinyurl.com/3bkvyvu5

2. Celltrion receives U.S. FDA approval for STOBOCLO® (denosumab-bmwo) and OSENVELT® (denosumab-bmwo) biosimilars referencing PROLIA® and XGEVA®. Prnewswire.com. March 3, 2025. Accessed July 10, 2025. https://tinyurl.com/yv8hp2s6