South Korea’s Celltrion has secured formulary agreements with one of the three largest U.S. pharmacy benefit managers (PBMs) for its osteoporosis treatment Stoqullo–Osenbelt (denosumab), gaining preferred-drug status ahead of the product’s first full year on the market.
The company said on December 1 that the biosimilar will be listed across all public and commercial insurance formularies managed by the PBM, with preferred placement beginning January 2025. The designation enables immediate patient reimbursement and is expected to accelerate early prescription uptake.
Stoqullo–Osenbelt is currently the only denosumab biosimilar listed by a top-three PBM in the United States. The listing signals strong confidence in Celltrion’s product competitiveness from one of the most influential players in the U.S. pharmaceutical supply chain, a critical factor in determining commercial success.
Celltrion’s U.S. subsidiary has also signed a preferred formulary agreement with another top-five PBM, covering all public and commercial insurance plans administered by that organization. Reimbursement for this agreement is also set to begin in January.
With these two contracts in place, Stoqullo–Osenbelt now has an estimated 30% coverage of the U.S. denosumab market, a notable milestone given that the product launched only four months ago. Because PBM agreements are essential for obtaining reimbursement in the high-cost U.S. drug market, early access to two major PBMs reflects strong expectations for the biosimilar’s commercial potential.
Celltrion is advancing additional formulary discussions with the remaining major PBMs. In the commercial insurance segment, Osenbelt has already secured coverage, and final steps remain for adding Stoqullo to those formularies. The company aims to quickly complete public-insurance agreements as well, with the goal of achieving comprehensive coverage across all large PBMs.
Beyond PBM contracts, Celltrion plans to aggressively pursue the U.S. “open market,” which accounts for roughly 30% of denosumab prescriptions and is largely unaffected by insurer or PBM controls. Success in this channel depends heavily on a manufacturer’s direct sales capabilities. Celltrion has already shown competitive strength here with its oncology biosimilar Vegzelma (bevacizumab), which has captured around 9% market share as of October.
Thomas Nusbickel, Chief Commercial Officer of Celltrion USA, said the rapid completion of major PBM listings provides a strong foundation to deliver high-quality biologics to U.S. patients at more accessible prices. He added that the company intends to leverage its commercial network to quickly establish a foothold in the U.S. bone-disease treatment market and drive further growth.
