Serum free light chain evaluation as a marker for the impact of intra-clonal heterogeneity on the progression and treatment resistance in multiple myeloma
Menée sur 520 patients atteints d'un myélome multiple, cette étude évalue l'intérêt de dosages sériques réguliers des chaînes légères libres pour prédire une récidive
Intra-clonal heterogeneity has recently been described in Multiple Myeloma (MM), but as yet the full clinical impact of this on disease progression and relapse has not been entirely explored. The immunoglobulin type produced by the plasma cells provides an excellent marker, which can be used to address this issue by allowing us to follow clonal sub-structure over time. We have prospectively evaluated serial paraprotein and serum free light chain (FLC) measurements and found that 258/520 and 54/520 patients who presented with a whole paraprotein relapsed with paraprotein only (PO) and "FLC escape", respectively. The median OS of PO patients was longer, when compared to patients whose relapse manifested as an increase in FLC both alone and in association with a whole paraprotein, as a result of a significantly shorter survival from relapse of the latter groups. These observations fit with a model in which one clone is able to produce a complete antibody, while the other secretes only FLC. In such a model the type of relapse represents the outgrowth of different clones, some of which are more resistant to therapy. To our knowledge this is the largest series describing patients who have relapsed with FLC escape and highlights the importance of monitoring FLC when there is a suspicion of clinical relapse. This study was registered at www.isrctn.org, identifier: ISRCTN68454111.
Blood , résumé, 2014