Critical analysis of the stringent complete response in multiple myeloma: contribution of sFLC and bone marrow clonality

Data de publicació: 13/08/2015

Autors de IIS La Fe

Lourdes Cordón Gallego

Autor

Autors aliens a IIS La Fe

Martínez-López J
Paiva B
López-Anglada L
Mateos MV
Cedena T
Vidríales MB
Sáez-Gómez MA
Contreras T
Oriol A
Rapado I
Teruel AI
Blanchard MJ
Bengoechea E
Palomera L
de Arriba F
Cueto-Felgueroso C
Orfao A
Bladé J
San Miguel JF
Lahuerta JJ
Spanish Multiple Myeloma Group / Program for the Study of Malignant Blood Diseas

Grups d'Investigació

Hematología y Hemoterapia

Investigador Principal

Javier De La Rubia Comos

Abstract

Stringent complete response (sCR) criteria are used in multiple myeloma as a deeper response category compared with CR, but prospective validation is lacking, it is not always clear how evaluation of clonality is performed, and is it not known what the relative clinical influence is of the serum free light chain ratio (sFLCr) and bone marrow (BM) clonality to define more sCR. To clarify this controversy, we focused on 94 patients that reached CR, of which 69 (73%) also fulfilled the sCR criteria. Patients with sCR displayed slightly longer time to progression (median, 62 vs 53 months, respectively; P = .31). On analyzing this contribution to the prognosis of sFLCr or clonality, it was found that the sFLCr does not identify patients in CR at distinct risk; by contrast, low-sensitive multiparametric flow cytometry (MFC) immunophenotyping (2 colors), which is equivalent to immunohistochemistry, identifies a small number of patients (5 cases) with high residual tumor burden and dismal outcome; nevertheless, using traditional 4-color MFC, persistent clonal BM disease was detectable in 36% of patients, who, compared with minimal residual disease-negative cases, had a significantly inferior outcome. These results show that the current definition of sCR should be revised.