title: The role of serum immunoglobulin free light chain in response and progression in waldenstrom macroglobulinemia.
abstract: BACKGROUND
  The serum free light chain (sFLC) has been widely used in the assessment of response in patients with multiple myeloma and other plasma cell dyscrasias. However, its use in Waldenstrom macroglobulinemia (WM) has not been previously assessed. We sought to examine the role of sFLC in response and progression of patients with WM.
  
  
  METHODS
  This study was conducted in a cohort of 48 patients with a diagnosis of WM, untreated (n = 20) or relapsed/refractory (n = 28), prospectively treated on a bortezomib and rituximab trial.
  
  
  RESULTS
  Involved FLC (iFLC) response occurred in 79% patients versus 60% by M-spike protocol criteria. The median time to response was shorter with iFLC than per protocol (2.1 and 3.7 months; P = 0.05). Progression defined using iFLC also correlated well to progression in the protocol (κ = 0.63). However, the median time to progression (TTP) was more rapid by iFLC than per protocol (13.7 and 18.9 months). We also confirmed that a flare in iFLC in post-rituximab therapy did not correlate with lack of response or shorter TTP.
  
  
  CONCLUSIONS
  Involved sFLC may be a useful marker of tumor measurement, showing earlier response and progression compared with IgM or M-spike measurements.
authors.affiliation: Department of Medical Oncology, Dana-Farber Cancer Institute and Harvard School of Public Health, Boston, Massachusetts, USA.
authors.forename: Xavier
authors.initials: X
authors.lastname: Leleu
authors.forename: Wanling
authors.initials: W
authors.lastname: Xie
authors.forename: Meghan
authors.initials: M
authors.lastname: Bagshaw
authors.forename: Ranjit
authors.initials: R
authors.lastname: Banwait
authors.forename: Renee
authors.initials: R
authors.lastname: Leduc
authors.forename: Nitin
authors.initials: N
authors.lastname: Roper
authors.forename: Edie
authors.initials: E
authors.lastname: Weller
authors.forename: Irene M
authors.initials: IM
authors.lastname: Ghobrial
mesh_terms: D058846:Antibodies, Monoclonal, Murine-Derived / Q000008:administration & dosage / Q000009:adverse effects; D000971:Antineoplastic Combined Chemotherapy Protocols / Q000009:adverse effects / Q000627:therapeutic use; D014408:Biomarkers, Tumor / Q000097:blood / Q000502:physiology; D001897:Boronic Acids / Q000008:administration & dosage / Q000009:adverse effects; D000069286:Bortezomib; D015331:Cohort Studies; D018450:Disease Progression; D005260:Female; D006801:Humans; D007147:Immunoglobulin Light Chains / Q000097:blood* / Q000502:physiology*; D008297:Male; D011719:Pyrazines / Q000008:administration & dosage / Q000009:adverse effects; D000069283:Rituximab; D016896:Treatment Outcome; D008258:Waldenstrom Macroglobulinemia / Q000097:blood* / Q000175:diagnosis* / Q000188:drug therapy* / Q000473:pathology
chemical_list: D058846:Antibodies, Monoclonal, Murine-Derived; D014408:Biomarkers, Tumor; D001897:Boronic Acids; D007147:Immunoglobulin Light Chains; D011719:Pyrazines; D000069283:Rituximab; D000069286:Bortezomib