Immunophenotypic Markers Associated with Minimal Residual Disease Status and Outcome in Patients with Multiple Myeloma Undergoing Autologous Stem Cell Transplantation

Multiple Myeloma (MM) is one of the most common hematologic malignancies, with a heterogeneous prognosis. Therefore, the recognition of biomarkers can be useful to understand the differences in patient outcomes. Minimal Residual Disease (MRD) has been considered a very important prognostic factor in MM. In parallel, the prognostic value of immunophenotypic markers expressed in MM Plasma Cells (PCs) has also been described. The aim of this study was to assess the impact of CD27, CD28, CD45, CD56, CD117 and β2-microglobulin expressions on the outcome of 154 MM patients undergoing Autologous Stem Cell Transplantation (ASCT). The relation of each marker studied with the Overall Survival (OS) and Progression-Free Survival (PFS) was assessed, alone and in association with pre-ASCT MRD. Scores of good (GPM) and poor Prognostic Markers (PPM) were established, according to their respective survival curves. The expressions of CD27 and CD45 were associated to longer OS (p=0.013 and p=0.00, respectively) and PFS (p=0.00) as well as the absence of CD28 (OS p=0.026; PFS p=0.001) and CD56 (OS p=0.004; PFS p=0.009), in patients with undetectable MRD. The number of GPM showed an inverse correlation with the level of MRD (p=0.04), while a higher number of PPM was observed in patients with higher levels of MRD (p=0.04), which were also significantly associated with OS and PFS. In conclusion, although pre-ASCT MRD is a powerful prognostic factor in MM, these biomarkers can provide additional prognostic information and be used in the follow-up of MM patients.