Biomarkers of bone remodeling in multiple myeloma patients to tailor bisphosphonate therapy

Patients with multiple myeloma may be susceptible to osteonecrosis of the jaw (ONJ) and stress fractures due to long-term aminobisphosphonate (aBP) therapy. However, it is unknown whether urinary N-telopeptide (NTX) or other bone biomarkers are predictive of skeletal-related events (SRE) or the impact of cessation of aBP therapy on bone remodeling.

We studied markers of bone turnover over a 6-month period after a single dose of zoledronic acid in 29 patients with multiple myeloma in remission who previously received 8 to 12 doses of pamidronate or zoledronate (NCT00577642). Our primary objective was to determine the duration of time urinary NTX levels remain suppressed after a single dose of zoledronate. A secondary objective was to identify and correlate other markers of bone remodeling with NTX changes. Thirty cytokines, based on their possible role in bone remodeling, were tested using cytokine arrays. Candidates were confirmed by ELISA.

All patients had continued suppression of NTX levels, except 1 patient who had an increase in NTX levels associated with an SRE. GDF-15 and decorin were found to decrease, whereas bone-specific alkaline phosphatase (BSALP) increased. Although not significant in aggregate, osteopontin and osteoprotegerin levels increased in at least half of the patients.

Our data show that NTX levels continue to be suppressed after aBP therapy, and suggest that suppressed NTX levels may be predictive of freedom from SRE in this patient population. Furthermore, osteoblast suppression by aBP may be reversible in myeloma. These data provide the basis for less frequent dosing of aBPs.