Bortezomib-based chemotherapy can improve renal and tubular functions in patients with light chain-associated Fanconi syndrome.

Light chain-associated Fanconi syndrome (LCFS) is a disorder of renal proximal tubule due to immunoglobulin light chains. Cases of LCFS are rare and mostly sporadically reported, and treatment of this entity is still controversial. This single-center retrospective study included 22 patients diagnosed with LCFS in Peking Union Medical College Hospital. Monoclonal gammopathy of undetermined significance was diagnosed in 13 patients, and overt multiple myeloma in six patients, with two smoldering myeloma and one Waldenstrom macroglobulinemia. Light chain was mostly kappa type (90.9%). Baseline median estimated glomerular filtration rate was 66 (13-126) ml/min/1.73 m2, with one patient presented as end-stage renal disease. After a median follow-up of 37 months, three patients died. Twelve patients were treated with chemotherapy, including 7 with bortezomib-based regimens. Renal function was significantly improved in the group of patients who received chemotherapy (p = 0.026). Compared with other chemotherapy regimens, patients with bortezomib-based treatment had a better hematological response (p = 0.027) as well as a better proximal tubule outcome (p = 0.015). Chemotherapy likely outweighs supportive treatment in patients with LCFS. Bortezomib-based regimen seems to be a safe first-line therapy for management of those patients.