title: Potential pitfalls of serum free light chain analysis to assess treatment response for multiple myeloma.
abstract: Response to treatment in patients with a plasma cell disorder is typically measured by evaluating the bone marrow and myeloma markers, including monoclonal protein spike and immunofixation (IFE) in blood and urine, and serum free light chains (sFLCs). Stringent complete response criteria for Multiple Myeloma (MM) patients require a normal FLC ratio and absence of clonal cells in bone marrow by immunohistochemistry or immunofluorescence. We performed a retrospective chart review to further evaluate these criteria. A total of 142 patient charts were analysed. Of these, 17 patients were found to have an abnormal sFLC ratio, but no other evidence of disease, including normal flow cytometry and normal fluorescence in situ hybridization (FISH) analysis on highly selected plasma cells. In all patients, the abnormal sFLC ratio was caused by abnormalities in the serum kappa light chains. These results suggest that current definitions may need to be revised to take aberrancies related to abnormal immune recovery into account.
authors.affiliation: Division of Hematology/Oncology and Blood & Marrow Transplantation, Department of Internal Medicine, University of Iowa Hospitals and Clinics, Iowa City, IA, USA.
authors.forename: Kamal Kant Singh
authors.initials: KK
authors.lastname: Abbi
authors.affiliation: Division of Hematology/Oncology and Blood & Marrow Transplantation, Department of Internal Medicine, University of Iowa Hospitals and Clinics, Iowa City, IA, USA.
authors.forename: Margarida
authors.initials: M
authors.lastname: Silverman
authors.affiliation: Division of Hematology/Oncology and Blood & Marrow Transplantation, Department of Internal Medicine, University of Iowa Hospitals and Clinics, Iowa City, IA, USA.
authors.forename: Umar
authors.initials: U
authors.lastname: Farooq
authors.affiliation: Division of Hematology/Oncology and Blood & Marrow Transplantation, Department of Internal Medicine, University of Iowa Hospitals and Clinics, Iowa City, IA, USA.
authors.forename: Annick
authors.initials: A
authors.lastname: Tricot
authors.affiliation: Division of Hematology/Oncology and Blood & Marrow Transplantation, Department of Internal Medicine, University of Iowa Hospitals and Clinics, Iowa City, IA, USA.
authors.forename: Lindsey
authors.initials: L
authors.lastname: Dozeman
authors.affiliation: Division of Hematology/Oncology and Blood & Marrow Transplantation, Department of Internal Medicine, University of Iowa Hospitals and Clinics, Iowa City, IA, USA.
authors.forename: Kalyan
authors.initials: K
authors.lastname: Nadiminti
authors.affiliation: Department of Pathology, University of Iowa Hospitals and Clinics, Iowa City, IA, USA.
authors.forename: Matthew D
authors.initials: MD
authors.lastname: Krasowski
authors.affiliation: Division of Hematology/Oncology and Blood & Marrow Transplantation, Department of Internal Medicine, University of Iowa Hospitals and Clinics, Iowa City, IA, USA.
authors.forename: Guido J
authors.initials: GJ
authors.lastname: Tricot
mesh_terms: D000328:Adult; D000368:Aged; D005260:Female; D005434:Flow Cytometry; D006801:Humans; D007147:Immunoglobulin Light Chains / Q000032:analysis*; D007145:Immunoglobulin kappa-Chains / Q000097:blood; D007146:Immunoglobulin lambda-Chains / Q000097:blood; D017404:In Situ Hybridization, Fluorescence; D008297:Male; D008875:Middle Aged; D009101:Multiple Myeloma / Q000175:diagnosis* / Q000276:immunology; D010950:Plasma Cells / Q000473:pathology; D012189:Retrospective Studies; D016896:Treatment Outcome
chemical_list: D007147:Immunoglobulin Light Chains; D007145:Immunoglobulin kappa-Chains; D007146:Immunoglobulin lambda-Chains
keywords: multiple myeloma; response criteria; serum free light chains