Rapid onset of osteonecrosis of the jaw in patients switching from bisphosphonates to denosumab

Objective. The aim of this study was to determine whether osteonecrosis of the jaw (ONJ) developed more rapidly in patients who switched from bisphosphonates (BP) treatment to denosumab than in patients who received only denosumab. Study Design. This was a retrospective cohort study conducted at a tertiary referral center. Thirty-one patients with ONJ met the inclusion criteria. Results. Twenty-two patients who had been on BP were switched to denosumab (BP + D), whereas 9 patients received only denosumab. Both groups were similar for the known ONJ risk factors, that is, age, diabetes mellitus, and smoking. The number and cumulative doses of denosumab before the onset of ONJ symptoms were significantly lower among the BP + D group compared with the denosumab-only group (P = .025 and .018, respectively). In the BP + D group, ONJ symptoms developed in 9 patients (41%) following the administration of <= 3 denosumab doses compared with ONJ developing in only 1 patient (11%) who was naive to BP. ONJ developed spontaneously without any known triggering event in 72.7% of patients in the BP + D group and in 77.8% of patients in the denosumab-only group. Conclusions. Denosumab-induced ONJ might develop rapidly in patients previously treated with BP. ONJ developed spontaneously in most patients treated with denosumab. In light of our sample being small, there is need for further investigation on our conclusions.