[Research Advance in Light Chain Escape of Multiple Myeloma -Review].

More than 80% of patients with MM is present as intact monoclonal immunoglobulin (Ig). Usually, the patients with intact immunoglobulin MM (IIMM) show parallel fluctuations of their intact Ig and FLCs or BJP. In the era of novel agents, including thalidomide, lenalidomide and bortezomib, the natural disease development and classic relapse patterns have been changed, the relapse was characterized by an increase in sFLC or BJP without a corresponding increase in paraprotein level, a phenomenon termed "light chain escape", indicates a worse outcome in patients with MM. This review focuses on the mechanism, clinical significance and early diagnosis of light chain escape.