Mass spectrometry vs immunofixation for treatment monitoring in multiple myeloma
Noemí Puig, María-Teresa Contreras, Cristina Agulló, Joaquín Martínez‐López, Albert Oriol, María‐Jesús Blanchard, Rafael Ríos, Jesús Martín, María-Belén Íñigo, Anna Sureda, Miguel-Teodoro Hernández, Javier de la Rubia, Verónica González‐Calle, Isabel Krsnik, Valentín Cabañas, Luis Palomera, José M. Moraleda, Joan Bargay, María‐Teresa Cedena, Bruno Paiva, Laura Rosiñol, Joan Bladé, Jesús F. San Miguel, Juan José Lahuerta, María‐Victoria Mateos
Abstract
Monitoring of the monoclonal protein (M-protein) by electrophoresis and/or immunofixation (IFE) has long been used to assess treatment response in multiple myeloma (MM). However, with the use of highly effective therapies, the M-protein becomes frequently undetectable, and more sensitive methods had to be explored. We applied IFE and mass spectrometry (EXENT&FLC-MS) in serum samples from newly diagnosed MM patients enrolled in the PETHEMA/GEM2012MENOS65 obtained at baseline (n = 223), and after induction (n = 183), autologous stem cell transplantation (n = 173), and consolidation (n = 173). At baseline, the isotypes identified with both methods fully matched in 82.1% of samples; in the rest but 2 cases, EXENT&FLC-MS provided additional information to IFE with regards to the M-protein(s). Overall, the results of EXENT&FLC-MS and IFE were concordant in >80% of cases, being most discordances due to EXENT&FLC-MS+ but IFE- cases. After consolidation, IFE was not able to discriminate 2 cohorts with different median progression-free survival (PFS), but EXENT&FLC-MS did so; furthermore, among IFE- patients, EXENT&FLC-MS identified 2 groups with significantly different median PFS (P = .0008). In conclusion, compared with IFE, EXENT&FLC-MS is more sensitive to detect the M-protein of patients with MM, both at baseline and during treatment, and provides a more accurate prediction of patients' outcome. This trial was registered at www.clinicaltrials.gov as #NCT01916252.