The Prevalence and Management of Multiple Myeloma-Induced Kidney Disease in China.

BACKGROUND: Multiple myeloma (MM) is a clonal B-cell malignancy of the bone marrow. Renal impairment is a common complication of MM. So far, there is no systematic overview of MM-induced kidney disease in China.
SUMMARY: The incidence of MM is 0.6/100,000 in China. Twenty-four, 19.7, and 30.8% of all patients with MM had renal insufficiency [defined by serum creatinine (Scr) ≥2 mg/dl] at diagnosis in China mainland, Hong Kong and Taiwan, respectively. Novel criteria based on the estimated glomerular filtration rate measurements are recommended for the assessment of renal function in patients with MM with stabilized Scr. It is reported that 78% of the MM patients had a creatinine clearance rate (Ccr) <90 ml/min, and 30.5% had a Ccr <30 ml/min. The IgG type was the most prevalent in MM patients; the light-chain and IgD type usually had a higher rate of kidney damage than others. New more effective drugs, blood purification technology and peripheral blood autologous stem cell transplantation have been introduced in clinical practice. Unfortunately, the studies conducted in the patients with renal insufficiency were almost all retrospective, had a small sample size and a short follow-up time. Although new treatments such as bortezomib are more widely used than before, traditional chemotherapy is still used, also because of economic constraints. The RIFLE criteria, which seem to be appropriate to define the severity of acute kidney injury (AKI), have been extensively validated worldwide but rarely in patients with MM. It was the first time to apply the RIFLE system to analyze the natural history of MM patients with AKI retrospectively in our unit. The severity of AKI defined by using the RIFLE criteria (OR = 2.04, p = 0.06) was associated with a marginal better long-term outcome. KEY MESSAGES: Novel criteria of renal insufficiency should be introduced into practice when treating MM. The treatment of MM patients with kidney disease has been greatly improved recently. It is necessary to conduct further large randomized controlled trials of the long-term outcome in China. FACTS FROM EAST AND WEST: (1) An Scr level >2 mg/dl has been reported in 16, 21, 24, and 33% of patients with MM in cohort studies of Japan, Europe, China, and Korea, respectively. A Ccr <30 ml/min was observed in 30 and 15% of patients in Chinese and Western MM cohorts, respectively. The commonest cause of severe renal impairment (RI) in patients with MM is myeloma cast nephropathy. (2) The efficacy of novel treatments (bortezomib, carfilzomib, thalidomide, and lenalidomide) has predominantly been assessed in Western patients. Bortezomib and dexamethasone are the current standard of care for MM and severe RI in the West. Severe RI is not a contraindication to autologous stem cell transplantation (ASCT). Most of the data are from the West; there are case reports from China describing good outcomes with ASCT. The removal of free light chain by high cutoff hemodialysis is under evaluation in randomized controlled trials (RCTs) in the West. Studies in this area are not yet conducted in China. In China, new treatments, such as bortezomib, are more widely used than before and favorable results are being reported; however, RCT studies are still needed in this area to confirm the efficacy and safety of this and other novel treatments.