title: Comparison of immunofixation, serum free light chain, and immunophenotyping for response evaluation and prognostication in multiple myeloma.
abstract: OBJECTIVE
  To investigate the impact of immunophenotypic response (IR) versus complete response (CR) and CR plus normal serum free light chain (sFLC) ratio (stringent CR) in elderly patients with multiple myeloma (MM) treated with novel agents.
  
  
  METHODS
  From a total of 260 elderly patients newly diagnosed with MM included in the GEM05>65y trial, 102 patients achieving at least a partial response with ≥ 70% reduction in M-component after the six planned induction cycles were simultaneously analyzed by immunofixation, sFLC, and multiparameter flow cytometry (MFC) immunophenotyping; this population is the focus of this study.
  
  
  RESULTS
  Forty-three percent of patients achieved CR, 30% achieved stringent CR, and 30% achieved IR. Patients in stringent CR showed no significant survival advantage compared with those in CR, whereas patients in IR showed significantly increased progression-free survival (PFS) and time to progression (TTP) compared with those in stringent CR or CR; this was confirmed by multivariate analysis (hazard ratio, 4.1; P = .01 for PFS). Discrepancies between the three techniques were relatively common. Notably, in all seven patients achieving IR but remaining immunofixation positive, the M-component disappeared in follow-up analysis. In contrast, MFC-positive patients who were immunofixation negative (n = 20) showed a tendency toward early reappearance of the M-component (median, 3 months). Similarly, in five of 11 stringent CR but MFC-positive patients, symptomatic disease progression was recorded at a median of 13 months after induction.
  
  
  CONCLUSIONS
  Achieving an IR translates into superior PFS and TTP compared with conventional CR or stringent CR. These techniques provide complementary information and thus, an effort should be made to refine response criteria in MM.
authors.affiliation: Hospital Universitario de Salamanca, Salamanca, Spain.
authors.forename: Bruno
authors.initials: B
authors.lastname: Paiva
authors.forename: Joaquin
authors.initials: J
authors.lastname: Martinez-Lopez
authors.forename: Maria-Belen
authors.initials: MB
authors.lastname: Vidriales
authors.forename: Maria-Victoria
authors.initials: MV
authors.lastname: Mateos
authors.forename: Maria-Angeles
authors.initials: MA
authors.lastname: Montalban
authors.forename: Elena
authors.initials: E
authors.lastname: Fernandez-Redondo
authors.forename: Lourdes
authors.initials: L
authors.lastname: Alonso
authors.forename: Albert
authors.initials: A
authors.lastname: Oriol
authors.forename: Ana-Isabel
authors.initials: AI
authors.lastname: Teruel
authors.forename: Raquel
authors.initials: R
authors.lastname: de Paz
authors.forename: José-Garcia
authors.initials: JG
authors.lastname: Laraña
authors.forename: Enrique
authors.initials: E
authors.lastname: Bengoechea
authors.forename: Alejandro
authors.initials: A
authors.lastname: Martin
authors.forename: Joaquin Diaz
authors.initials: JD
authors.lastname: Mediavilla
authors.forename: Luis
authors.initials: L
authors.lastname: Palomera
authors.forename: Felipe
authors.initials: F
authors.lastname: de Arriba
authors.forename: Joan
authors.initials: J
authors.lastname: Bladé
authors.forename: Alberto
authors.initials: A
authors.lastname: Orfao
authors.forename: Juan-Jose
authors.initials: JJ
authors.lastname: Lahuerta
authors.forename: Jesus F
authors.initials: JF
authors.lastname: San Miguel
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D000971:Antineoplastic Combined Chemotherapy Protocols / Q000627:therapeutic use; D014408:Biomarkers, Tumor / Q000097:blood*; D018572:Disease-Free Survival; D005260:Female; D005434:Flow Cytometry; D005455:Fluorescent Antibody Technique; D006801:Humans; D007147:Immunoglobulin Light Chains / Q000097:blood*; D007158:Immunologic Techniques; D016130:Immunophenotyping; D053208:Kaplan-Meier Estimate; D008297:Male; D009101:Multiple Myeloma / Q000188:drug therapy / Q000276:immunology* / Q000401:mortality; D009391:Nephelometry and Turbidimetry; D011237:Predictive Value of Tests; D016016:Proportional Hazards Models; D011446:Prospective Studies; D018570:Risk Assessment; D012307:Risk Factors; D013030:Spain; D015996:Survival Rate; D013997:Time Factors; D016896:Treatment Outcome
chemical_list: D014408:Biomarkers, Tumor; D007147:Immunoglobulin Light Chains