title: Evaluation of the serum free light chain (sFLC) analysis in prediction of response in symptomatic multiple myeloma patients: rapid profound reduction in involved FLC predicts achievement of VGPR.
abstract: BACKGROUND
  Observational data from clinical studies indicate that the goal of first-line therapy in newly diagnosed patients with symptomatic multiple myeloma (MM) should be very good partial response (VGPR) or better, preferably before high-dose treatment. We evaluated the value of early measurements of involved free light chains (iFLC) in prediction of high-quality responses. Measuring iFLC has a potential advantage due to a short half-life compared to the half-life of the M-protein.
  
  
  METHODS
  In 36 multiple myeloma (MM) patients, we measured serial changes in iFLC and M-protein after start of treatment. iFLC and M-protein were measured before treatment, the following 5 wk days, 2, 3 and 6 wks after start of treatment.
  
  
  RESULTS
  Median iFLC and M-protein half-life was 2.75 and 11.9 d, respectively. All patients with an iFLC >75 mg/L had an initial significant reduction (>20%) in iFLC, even patients with no response to treatment. The mean per cent reduction in iFLC 3 d after start of treatment was 52.3% and 23.6% (P = 0.021) in patients achieving ≥VGPR and PR, respectively. The mean per cent reduction in M-protein in patients achieving ≥VGPR and PR was not significantly different in the 6-wk study period. As a predictor of VGPR, an 80% reduction in iFLC at day 21 resulted in a sensitivity of 87.5% and a specificity of 100%.
  
  
  CONCLUSIONS
  Changes in iFLC could be a tool for early identification of responders to anti-myeloma therapy. Early, sequential measurements of iFLC within the first week after start of treatment are not meaningful.
authors.affiliation: Department of Haematology, Odense University Hospital, Odense, Denmark.
authors.forename: Charlotte T
authors.initials: CT
authors.lastname: Hansen
authors.forename: Per T
authors.initials: PT
authors.lastname: Pedersen
authors.forename: Lars C
authors.initials: LC
authors.lastname: Nielsen
authors.forename: Niels
authors.initials: N
authors.lastname: Abildgaard
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D000971:Antineoplastic Combined Chemotherapy Protocols; D001897:Boronic Acids / Q000008:administration & dosage; D000069286:Bortezomib; D003520:Cyclophosphamide / Q000008:administration & dosage; D003907:Dexamethasone / Q000008:administration & dosage; D016903:Drug Monitoring; D005260:Female; D006207:Half-Life; D006801:Humans; D007147:Immunoglobulin Light Chains / Q000097:blood*; D000077269:Lenalidomide; D008297:Male; D008558:Melphalan / Q000008:administration & dosage; D008875:Middle Aged; D009101:Multiple Myeloma / Q000097:blood / Q000175:diagnosis* / Q000188:drug therapy* / Q000473:pathology; D009194:Myeloma Proteins / Q000378:metabolism*; D011241:Prednisone / Q000008:administration & dosage; D011446:Prospective Studies; D011719:Pyrazines / Q000008:administration & dosage; D012680:Sensitivity and Specificity; D013792:Thalidomide / Q000008:administration & dosage / Q000031:analogs & derivatives; D016896:Treatment Outcome
chemical_list: D001897:Boronic Acids; D007147:Immunoglobulin Light Chains; D009194:Myeloma Proteins; D011719:Pyrazines; C085016:multiple myeloma M-proteins; D013792:Thalidomide; D000069286:Bortezomib; D003907:Dexamethasone; D003520:Cyclophosphamide; D000077269:Lenalidomide; D008558:Melphalan; D011241:Prednisone
keywords: half-life; immunoglobulin light chains; multiple myeloma; treatment outcome