Denosumab Biosimilars Conexxence and Bomyntra Receive Interchangeability Designation

The FDA designated 2 denosumab biosimilars, Conexxence and Bomyntra (denosumab-bnht; Fresenius Kabi), as interchangeable biosimilars to their respective reference products, Prolia and Xgeva (Amgen).¹

Following Bildyos (denosumab-nxxp injection 60 mg/mL) and Bilprevda (denosumab-nxxp 120 mg/1.7 mL; Shanghai Henlius Biotech, Organon) and Bosaya (denosumab-kyqq 60 mg/mL subcutaneous injection) and Aukelso (denosumab-kyqq 120 mg/1.7 mL; Biocon Biologics Ltd.), this is the third pair of denosumab biosimilars to receive interchangeability designations from the FDA since September 2, 2025.^2,3

Like Prolia, Conexxence is approved for use in various adult patients who are at high risk for fractures, including those with osteoporosis, patients undergoing certain cancer treatments that impact bone density, and patients receiving long-term glucocorticoid therapy. In the US, Conexxence has a boxed warning and includes a Risk Evaluation and Mitigation Strategy (REMS) program, with the goal to educate prescribers and patients about the risk of severe hypocalcemia in patients with advanced chronic kidney disease, including those on dialysis. This biosimilar is contraindicated in patients with hypocalcemia, during pregnancy, and in cases of known hypersensitivity to denosumab products.¹

Bomyntra is also approved for the prevention of skeletal-related events in patients with multiple myeloma and in patients with bone metastases from solid tumors, like Xgeva. Additionally, it is indicated for the treatment of hypercalcemia of malignancy that is refractory to bisphosphonate therapy and the treatment of adults and skeletally mature adolescents with giant cell tumor of bone that is either unresectable or where surgical resection is likely to result in severe morbidity. Like Conexxence, Bomyntra is contraindicated in patients with hypocalcemia and those with known hypersensitivity to denosumab products; however, the manufacturers did not state whether it is contraindicated for pregnant patients.¹

The designation was announced the day after the Department of Health and Human Services (HHS), FDA, and Centers for Medicare and Medicaid Services (CMS) announced a strategy to accelerate approvals for biosimilars. The aim, according to the agencies, is to reduce the number of human clinical trials required for certain biosimilars and alter the interchangeability process.⁴

Such a process will involve the FDA releasing a new draft guidance for biosimilar development that states companies do not need to conduct large, expansive, comparative human trials in lieu of advanced testing to determine equivalence. The agency released streamlined draft guidance outlining recommendations for comparative efficacy studies (CES) for biosimilars. In the guidance, the FDA notes that CESs have lower sensitivity than comparative analytical assessments, meaning the removal of resource-intensive human clinical studies can enable more efficient, cheaper development. Marty Makary, MD, MPH, FDA Commissioner, stated that the new strategy is projected to “cut the development time of biosimilars from 5 to 8 years in half while lowering drug prices.”⁴

The FDA also stated its plan to eliminate “bureaucratic” switching studies for interchangeability status to take a “strong stand instead to advance and promote interchangeability.” Such additional studies can slow the development of biosimilars and create confusion regarding their safety. Loosening interchangeability regulations will provide pharmacists and patients with more access to biosimilars.⁴

“Fresenius Kabi is pleased to receive this interchangeable designation for Conexxence and Bomyntra to create access for patients and health care professionals to important, high-quality therapies at a reduced cost,” Sang-Jin Pak, MD, president of Biopharma and member of the Fresenius Kabi Management Board, said in a news release from the manufacturer.¹

REFERENCES

1. Fresenius Kabi. FDA Grants Interchangeable Designation to Fresenius Kabi’s Biosimilars Conexxence® and Bomyntra® (denosumab-bnht). News release. October 30, 2025. Accessed October 30, 2025. https://www.fresenius-kabi.com/us/news-and-events/interchangeable-designation-granted-conexxence-bomyntra

2. McGovern G. FDA Approves Bildyos and Bilprevda, Biosimilars of Reference Denosumab. Pharmacy Times. September 2, 2025. Accessed October 30, 2025. https://www.pharmacytimes.com/view/fda-approves-bildyos-and-bilprevda-biosimilars-of-reference-denosumab

3. McGovern G. FDA Approves Bosaya and Aukelso, Biosimilars to Reference Denosumab. Pharmacy Times. September 17, 2025. Accessed October 30, 2025. https://www.pharmacytimes.com/view/fda-approves-bosaya-and-aukelso-biosimilars-to-reference-denosumab

4. Halpern L. FDA, HHS Move to Accelerate Biosimilar Approvals. Pharmacy Times. October 29, 2025. Accessed October 30, 2025. https://www.pharmacytimes.com/view/fda-hhs-move-to-accelerate-biosimilar-approvals