Serum free light chains, not urine specimens, should be used to evaluate response in light-chain multiple myeloma - Université de Rennes Access content directly
Journal Articles Blood Year : 2016

Serum free light chains, not urine specimens, should be used to evaluate response in light-chain multiple myeloma

Odile Luycx
  • Function : Author
Olivier Allangba
  • Function : Author
Laurence Legros
  • Function : Author
Mamoun Dib
  • Function : Author
Brigitte Pegourie
  • Function : Author
Frederique Orsini-Piocelle
  • Function : Author
Laurent Garderet
  • Function : Author
  • PersonId : 949876
Mohamad Mohty
  • Function : Author
  • PersonId : 953688
Nathalie Meuleman
  • Function : Author
Chantal Doyen
  • Function : Author
Xavier Leleu
  • Function : Author
Philippe Moreau
Cyrille Hulin
  • Function : Author
Philippe Rodon
  • Function : Author
Carla Araujo
  • Function : Author

Abstract

Guidelines for monitoring multiple myeloma (MM) patients expressing light chains only (light-chain MM [LCMM]) rely on measurements of monoclonal protein in urine. Alternatively, serum free light chain (sFLC) measurements have better sensitivity over urine methods, however, demonstration that improved sensitivity provides any clinical benefit is lacking. Here, we compared performance of serum and urine measurements in 113 (72κ, 41λ) newly diagnosed LCMM patients enrolled in the Intergroupe Francophone du Myélome (IFM) 2009 trial. All diagnostic samples (100%) had an abnormal κ:λ sFLC ratio, and involved (monoclonal) FLC (iFLC) expressed at levels deemed measurable for monitoring (≥100 mg/L). By contrast, only 64% patients had measurable levels of monoclonal protein (≥200 mg per 24 hours) in urine protein electrophoresis (UPEP). After 1 and 3 treatment cycles, iFLC remained elevated in 71% and 46% of patients, respectively, whereas UPEP reported a positive result in 37% and 18%; all of the patients with positive UPEP at cycle 3 also had elevated iFLC levels. Importantly, elevated iFLC or an abnormal κ:λ sFLC ratio after 3 treatment cycles associated with poorer progression-free survival (P = .006 and P < .0001, respectively), whereas positive UPEP or urine immunofixation electrophoresis (uIFE) did not. In addition, patients with an abnormal κ:λ sFLC ratio had poorer overall survival (P = .022). Finally, early normalization of κ:λ sFLC ratio but not negative uIFE predicted achieving negative minimal residual disease, as determined by flow cytometry, after consolidation therapy (100% positive predictive value). We conclude that improved sensitivity and prognostic value of serum over urine measurements provide a strong basis for recommending the former for monitoring LCMM patients.

Domains

Genetics

Dates and versions

hal-01439375 , version 1 (18-01-2017)

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Charlotte Fontan, Mourad Tiab, Pascal Godmer, Odile Luycx, Olivier Allangba, et al.. Serum free light chains, not urine specimens, should be used to evaluate response in light-chain multiple myeloma. Blood, 2016, 128 (25), pp.2941-2948. ⟨10.1182/blood-2016-07-726778⟩. ⟨hal-01439375⟩
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