Biosimilar denosumab could save $0.59 per member per month

Even a small discount of 5% for a biosimilar that references Xgeva and Prolia could mean millions of dollars of savings for a health plan, according to a budget impact model published online at the Journal of Medical Economics in October 2025.

“In a hypothetical health plan covering 1 million lives, adding biosimilar denosumab to a health plan formulary may contribute to significant cost savings; savings can be reinvested to further expand access to biosimilar denosumab,” the authors wrote.

Denosumab is a monoclonal antibody that slows bone resorption, which is the process by which bone tissue is broken down and released into the bloodstream. When this happens excessively, it can lead to complications such as osteoporosis and bone fractures. Osteoporosis is a natural part of aging for many women who have gone through menopause, but certain cancer treatments can also weaken bone structure.

Prolia (used to treat women with osteoporosis) and Xgeva (used to prevent bone-related events in people with multiple myeloma and bone metastases) are the branded denosumab products. They were developed and are marketed by Amgen.

As of November, eight pairs of denosumab biosimilars have been approved by the FDA, and five pairs have been launched in the United States. Wyost and Jubbonti, the first set of denosumab approved by the FDA in March 2024, are interchangeable for the reference products and are approved for all of the same indications in bone cancer and osteoporosis and have the same dosage form, route of administration, and dosing regimen as the reference medicines.

Sandoz launched Wyost and Jubbonti in June 2025. Wyost (for multiple myeloma and bone metastases) and Jubbonti (for osteoporosis) were both priced at $26.74 per mg. This is 7% lower than Xgeva and 14.5% lower than Prolia, a company spokesperson said at the time. Wyost and Jubbonti have the same Medicare Part B (fee for service) coverage as Prolia and Xgeva, with no step edits or prior authorization required. This accounts for 35% to 40% of the market, according to the spokesperson.

In the Journal of Medical Economics study, which was sponsored by Sandoz, researchers wanted to understand the potential financial impact of adding biosimilar denosumab to the formulary. This study was led by Jeanine Flanigan, Pharm.D., who was previously with Sandoz and is now a pharmacist with the Allegheny Health Network. Flanigan and her colleagues looked at the cost of switching from original denosumab to biosimilar denosumab.

They conducted an economic analysis of the impact of incorporating biosimilar denosumab into a plan formulary for oncology indications. Researchers also wanted to assess the costs associated with skeletal-related events such as fractures, bone destruction, and pain. Patients with cancers such as prostate, breast, and multiple myeloma are at high risk of skeletal-related events.

They developed a hypothetical model that assumed a health plan covering 1 million lives, with a target population including patients with metastatic breast cancer, prostate cancer, multiple myeloma, and solid tumors.

The first analysis calculated the direct cost savings from converting patients from the branded products (Prolia and Xgeva) to a biosimilar. A second model explored a reinvestment scenario where the realized savings were used to transition patients currently treated with zoledronic acid to biosimilar denosumab. Zoledronic acid slows the loss of calcium in the bone and is used to prevent and treat osteoporosis and Paget’s disease.

Researchers in this analysis found that in these scenarios, payers who adopted biosimilar denosumab were able to achieve savings. In the base case scenario, which assumed a medium market conversion rate reaching 57.30% for oncology indications and 81.79% for osteoporosis indications by year five, the total cost savings was $38,677,606, or $0.59 per member per month (PMPM).

The investigators also modeled high- and low-conversion scenarios to account for market variability. A high conversion rate yielded a five-year net savings of approximately $55.9 million ($0.85 PMPM), while a low conversion rate still resulted in savings of roughly $23 million ($0.35 PMPM).

Even with a conservative 5% price reduction relative to the reference product, this hypothetical plan saved more than $5.7 million. On the other end of the spectrum, an 85% price reduction resulted in projected savings of nearly $97 million over the five-year horizon.

Other biosimilar denosumabs on the U.S. market include:

• Celltrion’s Osenvelt and Stoboclo, which launched in July 2025
• Fresenius Kabi’s Bomyntra and Conexxence, which launched in July 2025
• Biocon Biologics Aukelso and Bosaya, which launched in October 2025
• Accord BioPharma’s Jubereq and Osvyrti, which launched in October 2025

The approved denosumab biosimilars that have not yet launched are:

• Gedeon Richter/Hikma Pharmaceuticals’ Xtrenbo and Enoby
• Shanghai Henlius Biotech/Organon’s Bilprevda and Bildyos
• Samsung Bioepis’ Xbryk and Ospomyv