Background: Bone involvement is frequently observed in multiple myeloma (MM) patients both at diagnosis and during the course of the disease. The evaluation of biochemical markers of bone turnover could allow a dynamic evaluation of the effects of a given therapy on bone metabolism.
Methods: In the present study, markers of bone resorption [urinary free pyridinoline (PYD), deoxypyridinoline (DPYD), N-terminal telopeptide of collagen I (NTX) and C-terminal telopeptide (serum crosslaps)] and of bone formation [bone alkaline phosphatase (BAP) and osteocalcin] were evaluated at diagnosis and after induction therapy in 40 patients (23M, 17F, median age = 53.5 yr) enrolled in the 'Bologna 2002' clinical trial. By study design, all patients received 4 months of combined thalidomide (100 mg/d for 2 wk then 200 mg/d), dexamethasone (40 mg/d on days 1-4, 9-12, 17-20/28 on odd cycles and on days 1-4 on even cycles) and zoledronic acid (4 mg/28 d).
Results: At diagnosis, although bone resorption markers were increased in more than 40% of the patients, only NTX (P = 0.029) and crosslaps (P = 0.000) were significantly related to the extent of skeletal lesions, as assessed by X-ray. After 4 months of therapy, a significant decrease in mean (+/-SE) urinary NTX (52.7 +/-6.9 nmol/mmol creatinine +/-6.9 vs. 14 +/- 1.42 nmol/mmol creatinine, P = 0.000) and serum crosslaps (6242.4 +/-945 pmol/L vs. 1414.9 +/- 173.8 pmol/L, P = 0.000) was observed in patients obtaining > or =partial response, at variance to what has been detected in patients showing <partial response.
Conclusions: Among all bone resorption markers, urinary NTX and serum crosslaps seem to be strictly related to the extent of bone involvement in MM. Combined thalidomide + dexamethasone and zoledronic acid seem to be highly effective in reducing bone resorption in sensitive patients, although the relative contribution of each drug cannot yet be determined.