Background: The effects of the bisphosphonate derivative zoledronic acid (ZA) on the circulating levels of matrix metalloproteinase-2 (MMP-2), matrix metallo-proteinases-9 (MMP-9), cathepsin B (Cath B) and urokinase-type plasminogen activator (uPA) in patients with bone metastasis (BMTS) and the possible correlation with the symptomatic response induced by this drug in these patients were evaluated.
Patients and methods: Proteinase levels were determined by enzyme-linked immunosorbent assay (ELISA) in the plasma of 30 patients with painful bone metastases from breast or prostate cancer undergoing multiple treatment with ZA (4 mg i.v., every 4 weeks). Healthy subjects (HS) of both genders (12 female and 30 male) served as the control group. The symptomatic response to ZA was assessed by the visual analog scale score (VAS).
Results: The median MMP-2 and MMP-9 pretreatment levels were more elevated in BMTS as compared to HS (p < or = 0.0001). Conversely, uPA levels were lower in BMTS p = 0.0033; no significant difference was observed for Cath B. ZA administration was associated with a symptomatic response (VAS score < or =4) in 25/30patients (83.3%) (p < 0.0001). This phenomenon paralleled a decrease of Cath B and MMP-2 plasma concentrations from baseline values on week 12 (p = 0.05). A similar trend, although not statistically significant, was also noted for MMP-9 and uPA. However, no direct relationship was observed between the analgesic effect induced by ZA and changes in the circulating levels of these enzymes.
Conclusion: These data show that ZA administration may provide relief from bone pain in patients with diffuse skeletal metastases and confirm a possible implication of cysteine proteinases and matrix metalloproteinases in bone metastasis formation, but not in the pathogenesis of metastatic bone pain.