Comparative effect of zoledronic acid versus denosumab on serum sclerostin and dickkopf-1 levels of naive postmenopausal women with low bone mass: a randomized, head-to-head clinical trial.

CONTEXT

Decreased bone formation due to a coupling effect limits bone mass increases after antiresorptive treatment.

OBJECTIVE

The purpose of this study was to compare the effects of 2 potent antiresorptive agents with different mechanism of action on serum levels of Wnt antagonists, sclerostin and dickkopf-1 (Dkk-1).

DESIGN

This was an interventional, parallel assignment, open-label, randomized clinical trial.

SETTING

The study was conducted at the outpatient clinics for metabolic bone diseases of 424 General Military Hospital, Thessaloniki, Greece.

PATIENTS AND INTERVENTIONS

Naive postmenopausal women with low bone mass were assigned to zoledronic acid infusion (n = 46) or denosumab injection (n = 46). One woman in the zoledronic acid group was lost to follow-up.

MAIN OUTCOME MEASURES

Serum sclerostin and Dkk-1 levels were the main outcomes. Secondary measurements were serum osteoprotegerin, receptor activator of nuclear factor κB ligand, procollagen type 1 N-terminal propeptide, and C-terminal cross-linking telopeptide of type 1 collagen.

RESULTS

Serum sclerostin levels significantly decreased in the zoledronic acid (P < .001) but increased in the denosumab group (P = .003). Dkk-1 levels significantly decreased in the zoledronic acid group (P = .006) but did not change in the denosumab group (P = .402). Serum osteoprotegerin remained essentially unchanged in either group, whereas receptor activator of nuclear factor κB ligand decreased in the zoledronic acid group (P = .004) but increased in the denosumab group (P = .037). Bone markers (procollagen type 1 N-terminal propeptide, C-terminal cross-linking telopeptide of type 1 collagen, and total serum alkaline phosphatase) decreased in both groups (all P < .001).

CONCLUSIONS

Although they both decrease bone resorption, zoledronic acid and denosumab exert opposite effects on Wnt signaling: the former decreases serum levels of both sclerostin and Dkk-1, whereas the latter increases sclerostin and does not affect Dkk-1.