The Dynamics of Nucleotide Variants in the Progression from Low-Intermediate Myeloma Precursor Conditions to Multiple Myeloma: Studying Serial Samples with a Targeted Sequencing Approach.

Multiple myeloma (MM), or Kahler's disease, is an incurable plasma cell (PC) cancer in the bone marrow (BM). This malignancy is preceded by one or more asymptomatic precursor conditions, monoclonal gammopathy of undetermined significance (MGUS) and/or smoldering multiple myeloma (SMM). The molecular mechanisms and exact cause of this progression are still not completely understood. In this study, the mutational profile underlying the progression from low-intermediate risk myeloma precursor conditions to MM was studied in serial BM smears. A custom capture-based sequencing platform was developed, including 81 myeloma-related genes. The clonal evolution of single nucleotide variants and short insertions and deletions was studied in serial BM smears from 21 progressed precursor patients with a median time of progression of six years. From the 21 patients, four patients had no variation in one of the 81 studied genes. Interestingly, in 16 of the 17 other patients, at least one variant present in MM was also detected in its precursor BM, even years before progression. Here, the variants were present in the pre-stage at a median of 62 months before progression to MM. Studying these paired BM samples contributes to the knowledge of the evolutionary genetic landscape and provides additional insight into the mutational behavior of mutant clones over time throughout progression.

Archival May-Grünwald-Giemsa-Stained Bone Marrow Smears Are an Eligible Source for Molecular DNA Research.

Biobanking is increasingly important in studying complex heterogeneous diseases. Therefore, it is essential to ensure the sample quality after long-term storage for reliable downstream analyses. The Clinical Biobank of the Jessa Hospital and the University Biobank Limburg (UBiLim) hold a continuously growing collection of hematological samples, including May-Grünwald-Giemsa (MGG)- and Perls' Prussian Blue (PPB)-stained bone marrow (BM) smears, stored at room temperature (RT) for up to 20 years. In this study, we investigated the effect of short- and long-term storage on the quality of DNA and RNA extracted from these BM smears to assess their fitness-for-purpose in downstream molecular applications, including agarose gel electrophoresis, bio-analyzer analysis, quantitative polymerase chain reaction (qPCR), and targeted next-generation sequencing (NGS). The RNA quality was very low for all samples, independent of storage time or staining method. The DNA from PPB-stained BM smears was already degraded after 1 year of storage and correspondingly could not be used for reliable downstream molecular analysis. In contrast, DNA extracted from MGG-stained BM smears stored for up to 10 years was able to generate high-quality data in qPCR and targeted NGS analyses. Longer storage periods (>15 years) of these samples revealed a high degree of degradation and a significant amount of DNA transitions and transversions. In conclusion, the DNA extracted from archival MGG-stained BM smears with a storage time up to at least 10 years was qualitatively good and fit for downstream analysis, including targeted NGS. This indicates that these samples are an eligible source for molecular DNA research and for studying complex diseases.

Prognostic Biomarkers in the Progression From MGUS to Multiple Myeloma: A Systematic Review.

Multiple myeloma (MM), characterized by malignant plasma cells in the bone marrow, is consistently preceded by asymptomatic premalignant stage monoclonal gammopathy of undetermined significance (MGUS). These MGUS patients have an annual risk of 1% to progress to MM. Clinical, imaging, and genomic (genetic and epigenetic) factors were identified, whose presence increased the risk of progression from MGUS to MM. In this systematic review we summarize the currently identified clinical, imaging, and genomic biomarkers suggested to increase the progression risk or shown to be differentially expressed/present between both cohorts of patients. Despite the wide range of proposed markers, there are still no reliable biomarkers to individually predict which MGUS patient will progress to MM and which will not. Research on biomarkers in the progression from MGUS to MM will give more insight in the unknown pathogenesis of this hematological malignancy. This would improve research by elucidating new pathways and potential therapeutic targets as well as clinical management by closer follow-up and earlier treatment of high-risk MGUS patients.