Prolia Fracture Risk Leads Public Citizen to Call For Black Box Warning

The consumer watchdog group Public Citizen is asking federal regulators to add a black box warning to Prolia, an osteoporosis drug that has been linked to an increased risk of bone fractures.

Public Citizen filed a petition (PDF) with the FDA on April 16, calling for the agency to require stronger warnings about the Prolia fracture risk.

The group indicates that information about the risk of fractures from Prolia after a user stops taking the drug should be placed in a prominent black box on the drug label, which is the strongest warning the FDA can require.

Prolia (denosumab) was introduced by Amgen in 2010, and was the first drug approved by the FDA for the treatment of postmenopausal osteoporosis.

Public Citizen first warned of potential link between Prolia and bone fractures in 2013, saying there were concerns about the drug even before it hit the market. Canadian drug regulators issued a warning of sudden femur fractures linked to Prolia in late 2012.

Amgen acknowledges there is an increased risk of fractures after a patient stops taking the drug, but company officials say they believe the benefits to patients outweigh the risks. However, Public Citizen’s petition says the science is pointing to those risks being bigger than first believed.

“There is a growing body of evidence showing that cessation of Prolia is associated with an increased risk of multiple vertebral fractures,” the petition states. “The risk of this serious adverse effect could be mitigated with a prominent boxed warning and an updated risk evaluation and mitigation strategy (REMS) that together would increase physician and patient awareness about the risks associated with treatment cessation. It also would discourage abrupt cessation of treatment or introduction of drug holidays without adequate consideration of alternative antiresorptive treatment options to protect patients from vertebral fractures.”

Public Citizen’s petition also includes what the group thinks would be appropriate and effective language for the boxed warning:

WARNING: MULTIPLE VERTEBRAL FRACTURES FOLLOWING DISCONTINUATION OF PROLIA TREATMENT

Following discontinuation of Prolia treatment, the risk of vertebral fractures, including the risk of multiple vertebral fractures, rapidly increases. Cessation of Prolia treatment results in markers of bone resorption increasing above pretreatment values then returning to pretreatment values 24 months after the last dose of Prolia. In addition, bone mineral density returns to pretreatment values within 18 months after the last injection [see Pharmacodynamics (12.2) and Clinical Studies (14.1)].

New vertebral fractures occurred as early as 7 months (on average 19 months) after the last dose of Prolia. Prior vertebral fracture was a predictor of multiple vertebral fractures after Prolia discontinuation. Evaluate an individual’s benefit-risk profile before initiating treatment with Prolia. Data from case series strongly suggests that vertebroplasty is not an effective treatment for vertebral fractures that occur following cessation of denosumab treatment and can cause additional vertebral fractures.

If Prolia treatment is discontinued, the patient should promptly receive a bisphosphonate or other alternative antiresorptive therapy to mitigate the increased risk of vertebral fracture [see Adverse Reactions (6.1)].