Loss of Heterozygosity and Mutations in the RAS-ERK Pathway Genes in Tumor Cells of Various Loci in Multiple Myeloma.

Multiple myeloma (MM) is a disease characterized by spatiotemporal heterogeneity of tumor clones. Different genetic aberrations can be observed simultaneously in tumor cells from different loci, and as the disease progresses, new subclones may appear. The role of liquid biopsy, which is based on the analysis of tumor DNA circulating in the blood plasma, continues to be explored in MM. Here, we present an analysis of the STR profiles and mutation status of the KRAS, NRAS, and BRAF genes, evaluated in plasma free circulating tumor DNA (ctDNA), CD138+ bone marrow cells, and plasmacytomas. The prospective single-center study included 97 patients, with a median age of 55 years. Of these, 94 had newly diagnosed symptomatic MM, and three had primary plasma cell leukemia. It should be noted that if mutations were detected only in ctDNA, "non-classical" codons were more often affected. A variety of adverse laboratory and clinical factors have been associated with the detection of rare KRAS or NRAS gene mutations in bone marrow or ctDNA, suggesting that these mutations may be factors of an unfavorable prognosis for MM. Liquid biopsy studies provide undeniable fundamental information about tumor heterogeneity and clonal evolution in MM. Moreover, we focus on using liquid biopsy to identify new high-risk factors for MM.

Results of Autologous Hematopoietic Stem Cell Transplantation in Patients with Multiple Myeloma(MM) and Renal Impairment: A Retrospective Single-Center Study.

Background: To assess the efficacy of autologous hematopoietic stem cell transplantation (auto-HSCT) in multiple myeloma (MM) patients with acute renal failure. Materials and Methods: A retrospective single-center study included 64 patients (30 men, 34 women) with MM and kidney damage at the onset of the disease, aged 19 to 65 years (median 54), who underwent auto-HSCT from 2013 to 2019. 23 patients (36%) were dialysis-dependent at the time of diagnosis. The analysis was carried out in two groups: the "HD-" group (patients who were independent of hemodialysis during auto-HSCT, n = 54), and the "HD +" group (patients who underwent auto-HSCT while treated with programmed hemodialysis, n = 10). Research results were statistically processed using the Statistica software (version 10.0); the data obtained were presented graphically. Statistical analysis was performed using survival analysis (using the Kaplan-Meier method, with a Log-Rank Test) and frequency analysis (using contingency tables and Fisher's test). Results: The patients dependent on hemodialysis were significantly more likely to require red blood cell transfusions compared to the dialysis-independent patients (100% versus 35%, p = 0.0001). Reactivation of a herpes viral infection and reversible toxic encephalopathy developed significantly more often in the patients from the "HD +" group compared with the patients from the "HD-" group (30% versus 6%, p = 0.04 and 20% versus 0%, p = 0.02, respectively). As a result of the treatment (induction + auto-HSCT), 14 patients (61%) became hemodialysis-independent. There was no transplant-related mortality. With a median follow-up of 48 months, the 5-year overall survival (OS) and progression-free survival (PFS) were 70% and 42%, respectively. Conclusion: Auto-HSCT is a safe and effective treatment for patients with MM complicated by acute kidney injury. Fourteen of 23 (61%) patients became dialysis-independent.

Loss of Heterozygosity in the Circulating Tumor DNA and CD138+ Bone Marrow Cells in Multiple Myeloma.

Multiple myeloma (MM) is characterized by heterogeneity of tumor cells. The study of tumor cells from blood, bone marrow, plasmacytoma, etc., allows us to identify similarities and differences in tumor lesions of various anatomical localizations. The aim of this study was to compare the loss of heterozygosity (LOH) by tumor cells by assessing STR profiles of different MM lesions. We examined paired samples of plasma circulating tumor DNA (ctDNA) and CD138+ bone marrow cells in MM patients. For patients with plasmacytomas (66% of 38 patients included), the STR profile of plasmacytomas was also studied when biopsy samples were available. Diverse patterns of LOH were found in lesions of different localization for most patients. LOH in plasma ctDNA, bone marrow, and plasmacytoma samples was found for 55%, 71%, and 100% of patients, respectively. One could expect a greater variety of STR profiles in aberrant loci for patients with plasmacytomas. This hypothesis was not confirmed-no difference in the frequency of LOH in MM patients with or without plasmacytomas was found. This indicates the genetic diversity of tumor clones in MM, regardless of the presence of extramedullar lesions. Therefore, we conclude that risk stratification based on molecular tests performed solely on bone marrow samples may not be sufficient for all MM patients, including those without plasmacytomas. Due to genetic heterogeneity of MM tumor cells from various lesions, the high diagnostic value of liquid biopsy approaches becomes obvious.