Withdrawal of Denosumab in Patients With Primary Hyperparathyroidism: A Follow-up Report of the DENOCINA Study

ObjectivesWe investigated the development in the primary outcomes: changes in bone mineral density (BMD) measured by dual x-ray absorptiometry at the lumbar spine, total hip, and femoral neck after 2 years.MethodsIn patients with primary hyperparathyroidism, we investigated the effects of 30-mg cinacalcet per day plus 60 denosumab every 6 months for 1 year (Deno group), versus denosumab plus placebo for 1 year (DenoPlacebo-group), versus placebo plus placebo injection for 1 year (Placebo group). After the study’s termination, most patients receiving denosumab were switched to bisphosphonate treatment.ResultsForty-three out of 45 participants were subject to follow-up. A total of 35 patients completed a 2-year follow-up dual x-ray absorptiometry-scan (Deno: n = 13; DenoPlacebo: n = 12; and Placebo: n = 10). None of the groups showed statistically significant changes in BMD or experienced decreases in mean BMD below the study’s baseline level. Overall, the changes in T-scores from the final study measurement to follow-up were similar among the groups (P = .38 for lumbar spine T-score, .63 for total hip, and .97 for femoral neck by 1-way ANOVA). P-calcium was not different over time (P = .20 for change over time and P = .08 for the difference between the groups by repeated measures ANOVA). A total of 5 participants suffered a fracture during the study or follow-up periods, all but one was in the placebo group.ConclusionEvidence suggests that it is possible to at least maintain BMD, and thus potentially lower the fracture risk by a short course of denosumab followed by antiresorptive therapy, where applicable in patients with primary hyperparathyroidism.