Costly vs. inexpensive BRI
The study found no difference in the OS benefit between the different BRIs used, that is, between that seen with zoledronic acid versus denosumab.
The editorialists suggested that this finding is important, even though it “must be considered preliminary given the limitations of a retrospective study.” These results add “to data suggesting that these agents are comparably beneficial; thus, decisions between them should focus on clinical factors, such as kidney function, patient preference, and cost.”
The two agents differ mechanistically, they added, with zoledronic acid preferentially inhibiting osteoclast proliferation and denosumab inhibiting an important factor in osteoclast maturation.
In terms of having differentiating characteristics, the editorialists say that zoledronic acid is “more often associated with acute phase reactions and required monitoring of kidney function” while “denosumab conferred a higher risk of hypocalcemia.” Rates of osteonecrosis of the jaw are comparable.
International guidelines endorse the use of either agent for the treatment of men with mCRPC. But “some argue that the marginal benefit of denosumab must be weighed against its dramatically higher cost (the annual cost of zoledronic acid is approximately $140 vs. $29,000 for denosumab),” the editorialists said.
The dramatically higher cost of denosumab versus zoledronic acid has also been noted by other oncologists treating patients with other cancers, including multiple myeloma.
In addition to drug costs, there is another issue at stake: the prescribing oncologist is reimbursed by Medicare Part D at 6% for whichever drug is chosen, which represents a “financial conflict” for oncologists, said Vincent Rajkumar, MD, professor of medicine and a hematologist/oncologist at the Mayo Clinic, Rochester, Minn.
There is also a difference in how the drugs are administered, which may influence patient preference, the myeloma experts noted. Zoledronic acid is given intravenously every 3 months and requires a 15-minute infusion at a center, while denosumab needs to be given more frequently (every month) but is administered by subcutaneous injection.
Dr. Francini reported receiving grants from Roche Italia and personal fees for research travel from Janssen-Cilag outside the submitted work. A number of other authors disclosed financial ties to Janssen or Amgen, makers of abiraterone and denosumab, respectively. The editorialists reported no relevant financial relationships.
A version of this article first appeared on Medscape.com.
