Dynamics of tumor-specific cfDNA in response to therapy in multiple myeloma patients.

OBJECTIVES: Progress in multiple myeloma treatment allows patients to achieve deeper responses, for which the assessment of minimal residual disease (MRD) is critical. Typically, bone marrow samples are used for this purpose; however, this approach is site-limited. Liquid biopsy represents a minimally invasive and more comprehensive technique that is not site-limited, but equally challenging. METHODS: While majority of current data comes from short-term studies, we present a long-term study on blood-based MRD monitoring using tumor-specific cell-free DNA detection by ASO-qPCR. One hundred and twelve patients were enrolled into the study, but long-term sampling and analysis were feasible only in 45 patients. RESULTS: We found a significant correlation of quantity of tumor-specific cell-free DNA levels with clinically meaningful events [induction therapy (P = .004); ASCT (P = .012)]. Moreover, length of cfDNA fragments is associated with better treatment response of patients. CONCLUSIONS: These results support the concept of tumor-specific cell-free DNA as a prognostic marker.

Cell-free DNA - Minimally invasive marker of hematological malignancies.

Although tumor cells are the most reliable source of tumor DNA, biopsy of the tumor is an invasive procedure that should be avoided in some cases. The main limitation of any biopsy is sampling of one tumor site, which may not represent all malignant clones due to the heterogeneity of the tumor. These clones respond to treatment differently and thus directly influence survival of the patient. Circulating cell-free DNA (cfDNA) is released from multiple tumor sites, reflects overall heterogeneity of the tumor, and correlates with its progression. Detection of tumor-specific genetic and epigenetic aberrations in cfDNA could have a direct impact on molecular diagnosis, prognosis, follow-up of disease, monitoring of minimal residual disease, and response to treatment. While most cfDNA data are still experimental, they are very promising. This review focuses on cfDNA in hematological malignancies.

Deregulated expression of long non-coding RNA UCA1 in multiple myeloma.

OBJECTIVES: Long non-coding RNAs (lncRNAs) are RNA transcripts longer than 200 nucleotides that are not translated into proteins. They are involved in pathogenesis of many diseases including cancer and have a potential to serve as diagnostic and prognostic markers. We aimed to investigate lncRNA expression profiles in bone marrow plasma cells (BMPCs) of newly diagnosed multiple myeloma (MM) patients in comparison to normal BMPCs of healthy donors (HD) in a three-phase biomarker study. METHODS: Expression profile of 83 lncRNA was performed by RT2 lncRNA PCR Array (Qiagen), followed by quantitative real-time PCR using specific TaqMan non-coding RNA assays analyzing 84 newly diagnosed MM patients and 25 HD. RESULTS: Our analysis revealed dysregulation of two lncRNAs; NEAT1 (sensitivity of 55.0% and specificity of 79.0%) and UCA1 (sensitivity of 85.0% and specificity of 94.7%). UCA1 levels correlated with albumin and monoclonal immunoglobulin serum levels, cytogenetic aberrations, and survival of MM patients. CONCLUSION: Our study suggests a possible prognostic impact of UCA1 expression levels on MM patients.

Circulating microRNA as Biomarkers in Hematological Malignancies.

Hematopoiesis is a highly regulated process controlled by a complex network of molecular mechanisms that simultaneously regulate differentiation, proliferation, and apoptosis of hematopoietic stem cells. Aberrant microRNA (miRNA) expression could affect normal hematopoiesis, leading to the development of hematological malignancies. Hematologic cancers, which are caused by malignant transformation of cells of the bone marrow and the lymphatic system, are usually divided into three major groups: leukemias, lymphomas, and monoclonal gammopathies. Hematologic malignancies are highly aggressive diseases with high morbidity and mortality. For these reasons, early and easily obtainable markers for diagnosis, risk stratification, and follow-up are essential for improvement of outcome and survival of these patients. Recent studies have provided new insights about the diagnostic value of expression patterns of miRNAs in serum/plasma in these diseases. While the use of circulating miRNAs is only at the experimental level, it appears to have a great potential. This chapter deals with the use of circulating miRNAs as minimally invasive biomarkers in hematologic malignancies.

MicroRNAs in urine are not biomarkers of multiple myeloma.

BACKGROUND: In this study, we aimed to identify microRNA from urine of multiple myeloma patients that could serve as a biomarker for the disease. RESULTS: Analysis of urine samples was performed using Serum/Plasma Focus PCR MicroRNA Panel (Exiqon) and verified using individual TaqMan miRNA assays for qPCR. We found 20 deregulated microRNA (p < 0.05); for further validation, we chose 8 of them. Nevertheless, only differences in expression levels of miR-22-3p remained close to statistical significance. CONCLUSIONS: Our preliminary results did not confirm urine microRNA as a potential biomarker for multiple myeloma.

Extramedullary relapse of multiple myeloma defined as the highest risk group based on deregulated gene expression data.

BACKGROUND: Multiple myeloma (MM) is characterized by malignant proliferation of plasma cells (PC) which accumulate in the bone marrow (BM). The advent of new drugs has changed the course of the disease from incurable to treatable, but most patients eventually relapse. One group of MM patients (10-15%) is considered high-risk because they relapse within 24 months. Recently, extramedullary relapse of MM (EM) has been observed more frequently. Due to its aggressivity and shorter survival, EM is also considered high-risk. AIMS: The goal of this study was to determine if the so-called high-risk genes published by the University of Arkansas group (UAMS) are even more deregulated in EM patients than in high-risk MM patients and if these patients may be considered high-risk. METHODS: Nine samples of bone marrow plasma cells from MM patients as well as 9 tumors and 9 bone marrow plasma cells from EM patients were used. Quantitative real-time PCR was used for evaluation of expression of 15 genes connected to the high-risk signature of MM patients. RESULTS: Comparison of high-risk plasma cells vs extramedullary plasma cells revealed 4 significantly deregulated genes (CKS1B, CTBS, NADK, YWHAZ); moreover, comparison of extramedullary plasma cells vs extramedullary tumors revealed significant differences in 9 out of 15 genes. Of these, 6 showed significant changes as described by the UAMS group (ASPM, SLC19A1, NADK, TBRG4, TMPO and LARS2). CONCLUSIONS: Our data suggest that increasing genetic abnormalities as described by the gene expression data are associated with increased risk for EM relapse.