title: Prediction of response and progression in multiple myeloma with serum free light chains assay: corroboration of the serum free light chain response definitions.
abstract: BACKGROUND
  The International Myeloma Working Group (IMWG) proposed response and progression criteria using serum free light chain (sFLC) testing for patients with nonsecretory multiple myeloma (MM). We attempt to validate these criteria by comparing paraprotein responses with sFLC responses in patients with secretory myeloma.
  
  
  METHODS
  Prospectively entered data for 89 patients with MM enrolled on various clinical trials at the Cleveland Clinic between April 2004 and December 2006 were reviewed.
  
  
  RESULTS
  By standard paraprotein criteria, 4 patients had complete remission (CR), 22 had partial remission (PR), 34 had stable disease (SD), 26 had progressive disease (PD), and 3 were inevaluable. Only 43 patients (48%) had an involved sFLC > or = 10 mg/dL (which is considered evaluable by the IMWG), of which 14 had PR, 8 had SD, 18 had PD, and 3 were inevaluable. The sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) for sFLC in predicting response were 81%, 83%, 64%, and 92% respectively. The sensitivity, specificity, PPV, and NPV for sFLC in predicting progression were 93%, 80%, 72%, and 95% respectively.
  
  
  CONCLUSIONS
  sFLC reliably predicts response and progression in MM. However, half of the patients had inevaluable disease by sFLC, thus limiting the utility of sFLC testing in patients with nonmeasurable disease by electrophoretic methods.
authors.affiliation: University of Michigan Hematology and Oncology Fellowship Program, Ann Arbor, MI, USA.
authors.forename: Rami
authors.initials: R
authors.lastname: Khoriaty
authors.forename: Mohamad A
authors.initials: MA
authors.lastname: Hussein
authors.forename: Beth
authors.initials: B
authors.lastname: Faiman
authors.forename: Megan
authors.initials: M
authors.lastname: Kelly
authors.forename: Matt
authors.initials: M
authors.lastname: Kalaycio
authors.forename: Rachid
authors.initials: R
authors.lastname: Baz
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D016026:Bone Marrow Transplantation; D003404:Creatinine / Q000097:blood; D018450:Disease Progression; D005260:Female; D006801:Humans; D007147:Immunoglobulin Light Chains / Q000097:blood*; D008297:Male; D008875:Middle Aged; D009101:Multiple Myeloma / Q000097:blood* / Q000401:mortality; D011379:Prognosis; D011446:Prospective Studies
chemical_list: D007147:Immunoglobulin Light Chains; D003404:Creatinine