Soluble c‐Met in serum of patients with multiple myeloma: correlation with clinical parameters

Objectives: The receptor tyrosine kinase c‐Met and its ligand, hepatocyte growth factor (HGF), play key roles in tumour genesis and metastasis and contribute in multiple myeloma pathogenesis. Substantial data support that a soluble extracellular fragment of c‐Met may function as a decoy receptor that downregulates the biological effects of HGF and c‐Met. We examined serum levels of soluble c‐Met in patients with myeloma and healthy individuals and investigated a possible relationship with clinical disease parameters and survival. Methods: The concentration of c‐Met and HGF was measured by enzyme‐linked immunosorbent assay in serum ( n  = 49) and bone marrow plasma ( n  = 16) from patients with multiple myeloma and in serum from healthy controls ( n  = 26). Results: The median serum concentration of soluble c‐Met was 186 ng/mL (range 22–562) in patients with multiple myeloma and 189 ng/mL (range 124–397) in healthy individuals. There was a significant negative correlation between serum c‐Met levels and disease stage, bone marrow plasma cell percentage and serum concentration of M‐protein. Conclusion: We have for the first time examined the concentration of soluble c‐Met in serum from patients with myeloma and found equal median levels in patients with myeloma as a group and healthy individuals. Still, serum levels of soluble c‐Met correlated negatively with parameters of disease burden in patients with myeloma. We suggest that a possible role for the c‐Met ectodomain as a negative regulator of HGF/c‐Met activity should be examined in multiple myeloma.