Improved Screening of Monoclonal Gammopathy Patients by MALDI-TOF Mass Spectrometry.

Monoclonal gammopathies are a group of blood diseases characterized by presence of abnormal immunoglobulins in peripheral blood and/or urine of patients. Multiple myeloma and plasma cell leukemia are monoclonal gammopathies with unclear etiology, caused by malignant transformation of bone marrow plasma cells. Mass spectrometry with matrix-assisted laser desorption/ionization and time-of-flight detection is commonly used for investigation of the peptidome and small proteome of blood plasma with high accuracy, robustness, and cost-effectivity. In addition, mass spectrometry coupled with advanced statistics can be used for molecular profiling, classification, and diagnosis of liquid biopsies and tissue specimens in various malignancies. Despite the fact there have been fully optimized protocols for mass spectrometry of normal blood plasma available for decades, in monoclonal gammopathy patients, the massive alterations of biophysical and biochemical parameters of peripheral blood plasma often limit the mass spectrometry measurements. In this paper, we present a new two-step extraction protocol and demonstrated the enhanced resolution and intensity (>50×) of mass spectra obtained from extracts of peripheral blood plasma from monoclonal gammopathy patients. When coupled with advanced statistics and machine learning, the mass spectra profiles enabled the direct identification, classification, and discrimination of multiple myeloma and plasma cell leukemia patients with high accuracy and precision. A model based on PLS-DA achieved the best performance with 71.5% accuracy (95% confidence interval, CI = 57.1-83.3%) when the 10× repeated 5-fold CV was performed. In summary, the two-step extraction protocol improved the analysis of monoclonal gammopathy peripheral blood plasma samples by mass spectrometry and provided a tool for addressing the complex molecular etiology of monoclonal gammopathies.

Daratumumab with lenalidomide and dexamethasone in relapsed or refractory multiple myeloma patients - real world evidence analysis.

We performed real world evidence (RWE) analysis of daratumumab, lenalidomide and dexamethasone (Dara-Rd) versus lenalidomide and dexamethasone (Rd) treatment in relapsed/refractory multiple myeloma patients (RRMM). In total, 240 RRMM patients were treated with Dara-Rd from 2016 to 2022 outside of clinical trials in all major Czech hematology centers. As a reference, 531 RRMM patients treated with Rd were evaluated. Patients' data were recorded in the Czech Registry of Monoclonal Gammopathies (RMG). Partial response (PR) or better response (ORR) was achieved in significantly more patients in Dara-Rd than in Rd group (91.2% vs. 69.9%; p < 0.001). The median progression free survival (PFS) was 26.9 months in the Dara-Rd and 12.8 months in the Rd group (p < 0.001). Median overall survival (OS) was not reached in the Dara-Rd compared to 27.2 months in the Rd group (p = 0.023). In patients with 1-3 previous treatment lines, there was significant PFS benefit of Dara-Rd compared to Rd (median PFS not reached vs. 13.2 months; p < 0.001). In patients with > 3 previous treatment lines, there was no significant PFS benefit of Dara-Rd treatment (7.8 months vs. 9.9 months; p = 0.874), similarly in patients refractory to PI + IMIDs (11.5 months vs. 9.2 months; p = 0.376). In RWE conditions, the median PFS in RRMM patients treated with Dara-Rd is shorter when compared to clinical trials. In heavily pretreated RRMM patients, efficacy of Dara-Rd treatment is limited; best possible outcomes of Dara-Rd are achieved in minimally pretreated patients.

More Than 2% of Circulating Tumor Plasma Cells Defines Plasma Cell Leukemia-Like Multiple Myeloma.

PURPOSE: Primary plasma cell leukemia (PCL) is the most aggressive monoclonal gammopathy. It was formerly characterized by ≥ 20% circulating plasma cells (CTCs) until 2021, when this threshold was decreased to ≥ 5%. We hypothesized that primary PCL is not a separate clinical entity, but rather that it represents ultra-high-risk multiple myeloma (MM) characterized by elevated CTC levels. METHODS: We assessed the levels of CTCs by multiparameter flow cytometry in 395 patients with newly diagnosed transplant-ineligible MM to establish a cutoff for CTCs that identifies the patients with ultra-high-risk PCL-like MM. We tested the cutoff on 185 transplant-eligible patients with MM and further validated on an independent cohort of 280 transplant-ineligible patients treated in the GEM-CLARIDEX trial. The largest published real-world cohort of patients with primary PCL was used for comparison of survival. Finally, we challenged the current 5% threshold for primary PCL diagnosis. RESULTS: Newly diagnosed transplant-ineligible patients with MM with 2%-20% CTCs had significantly shorter progression-free survival (3.1 v 15.6 months; P < .001) and overall survival (14.6 v 33.6 months; P = .023) than patients with < 2%. The 2% cutoff proved to be applicable also in transplant-eligible patients with MM and was successfully validated on an independent cohort of patients from the GEM-CLARIDEX trial. Most importantly, patients with 2%-20% CTCs had comparable dismal outcomes with primary PCL. Moreover, after revealing a low mean difference between flow cytometric and morphologic evaluation of CTCs, we showed that patients with 2%-5% CTCs have similar outcomes as those with 5%-20% CTCs. CONCLUSION: Our study uncovers that ≥ 2% CTCs is a biomarker of hidden primary PCL and supports the assessment of CTCs by flow cytometry during the diagnostic workup of MM.

Immunomodulatory Agents for Multiple Myeloma.

The treatment of multiple myeloma (MM) has undergone a significant paradigm shift in the last 20 years, from conventional chemotherapy to more tumor-specific treatments, based on the interference with pathogenesis of the malignant clone as well as the bone microenvironment [...].

Involvement of Small Non-Coding RNA and Cell Antigens in Pathogenesis of Extramedullary Multiple Myeloma.

Extramedullary multiple myeloma (EMD) is an aggressive disease; malignant plasma cells lose their dependence in the bone marrow microenvironment and migrate into tissues. EMD is a negative prognostic factor of survival. Using flow cytometry and next-generation sequencing, we aimed to identify antigens and microRNAs (miRNAs) involved in EMD pathogenesis. Flow cytometry analysis revealed significant differences in the level of clonal plasma cells between MM and EMD patients, while the expression of CD markers was comparable between these two groups. Further, miR-26a-5p and miR-30e-5p were found to be significantly down-regulated in EMD compared to MM. Based on the expression of miR-26a-5p, we were able to distinguish these two groups of patients with high sensitivity and specificity. In addition, the involvement of deregulated miRNAs in cell cycle regulation, ubiquitin-mediated proteolysis and signaling pathways associated with infections or neurological disorders was observed using GO and KEGG pathways enrichment analysis. Subsequently, a correlation between the expression of analyzed miRNAs and the levels of CD molecules was observed. Finally, clinicopathological characteristics as well as CD antigens associated with the prognosis of MM and EMD patients were identified. Altogether, we identified several molecules possibly involved in the transformation of MM into EMD.

IgG4-related disease. Clinical manifestation differential diagnosis and recent International Diagnostic Criteria for IgG4-related disease.

Immunoglobulin G4- related disease (IgG4-RD) is a rare systemic fibro-inflammatory disorder. Autoimmune pancreatitis is the most frequent manifestation of IgG4-RD. However, IgG4-RD can affect any organ such as salivary glands, orbits, retroperitoneum, prostate and many others. Recent research enabled a clear clinical and histopathological description of IgG4-RD and in 2019 four Clinical phenotypes of IgG4-related disease were described. Diagnosis is based on morphological examination with typical findings of lymphoplasmocellular inflammation, storiform fibrosis and obliterative phlebitis in IgG4-RD biopsies and the tissue invading plasma cells largely produce IgG4. Elevated serum IgG4 levels are found in many but not all patients. New diagnostic criteria for IgG4-RD have been published recently in 2019 and 2021. This review summarizes current knowledge on pathophysiology, clinical manifestations, diagnosis and differential diagnosis of IgG4-RD from the point of view 2022 and in next article brings overview of the IgG4-RD therapy.

Langerhans cell histiocytosis (LCH). Overview of symptoms of LCH, which may lead the patients to any of these medical specialists.

Langerhans cell histiocytosis (LCH) is a rare condition with incidence in adults 1-2/1 million, wherein Langerhans cells proliferate abnormally, adversely impacting organs including most frequently bones, skin, lungs, pituitary gland, lymph nodes, gums and other organs. The LCH course varies widely among patients from a self-limiting condition, to one that progresses. But LCH only very rarely culminates in death. To aim of this text is to review all possible symptoms and manifestations of this disease.

Unexpected Heterogeneity of Newly Diagnosed Multiple Myeloma Patients with Plasmacytomas.

In multiple myeloma (MM), malignant plasma cells infiltrate the bone marrow. In some cases, plasma cells migrate out of the bone marrow creating either para-skeletal plasmacytomas (PS) or infiltrating soft tissues as extramedullary plasmacytomas (EMD). The aim of this study was to define risk groups in newly diagnosed MM (NDMM) patients with PS and EMD plasmacytomas. In total, 523 NDMM patients with PS plasmacytomas and 196 NDMM patients with EMD plasmacytomas were diagnosed in the Czech Republic between 2004 and 2021 using modern imaging methods. Patients' data were analyzed from the Registry of Monoclonal Gammopathies of the Czech Myeloma Group. In NDMM patients with PS plasmacytomas, we found a subgroup with <5% of bone-marrow plasma cells to have the best prognosis (mPFS: 58.3 months (95% CI: 33.0−NA); mOS: not reached). The subgroup with >5% of bone-marrow plasma cells and ≥3 plasmacytomas had the worst prognosis (mPFS: 19.3 months (95% CI: 13.4−28.8), p < 0.001; mOS: 27.9 months (95% CI: 19.3−67.8), p < 0.001). Our results show association between tumor burden and prognosis of NDMM patients with plasmacytomas. In the case of PS plasmacytomas, NDMM patients with low BM PC infiltration have an excellent prognosis.

Multicentric Castlemans disease. Symptoms, diagnostics and therapy.

Castleman disease (CD) describes a group of heterogeneous hematologic disorders with characteristic histopathological features. CD can present with unicentric (UCD) or multicentric (MCD) regions of lymph node enlargement. Some cases of MCD are caused by human herpesvirus-8 (HHV-8), whereas others are HHV-8-negative/idiopathic (iMCD). Treatment of iMCD is challenging, and outcomes can be poor. In this paper, we briefly report about symptoms of iMCD and about the International, evidencebased consensus diagnostic criteria for HHV-8-negative/idiopathic multicentric Castleman disease and International evidence based consensus treatment guidelines for idiopathic multicentric Castleman disease.

Proteomic analysis of the bone marrow microenvironment in extramedullary multiple myeloma patients.

Multiple myeloma (MM) is a heterogeneous hematological malignancy characterized by the uncontrolled clonal proliferation of bone marrow (BM) plasma cells. The poor prognosis of patients is associated with the presence of extramedullary disease (EMD). Previously, different mechanisms involved in the colonization of BM niches by MM cells and their escape during EMD have been described. Thus, we aimed to investigate the expression of selected cytokines in the BM plasma of MM patients as well as EMD patients to reveal novel molecules involved in EMD pathogenesis. Expression of 120 different cytokines was measured in BM plasma of 13 MM and 11 EMD patients using Proteome Profiler Antibody Arrays. The correlation between statistically significant cytokines and clinicopathological parameters of patients was determined using the Spearman correlation analysis. Finally, protein-protein interactions were analyzed, and GO and KEGG pathways enrichment analysis was performed. In total, 27 cytokines were found to be differently expressed between MM and EMD patients. After the Benjamini-Hochberg correction for multiple testing, the statistical significance of two cytokines downregulated in EMD (EGF, BDNF) and six cytokines upregulated in EMD (NAP-2, ADIPOQ, CRP, MIG, BAFF, and THBS1) was maintained. Correlation analysis proved a significant association between the expression of these molecules and selected clinical-pathological features of MM/EMD patients. Protein association network analysis revealed important protein-protein interactions between THBS1/EGF, MIG/NAP-2, THBS1/NAP-2, EGF/NAP-2, and ADIPOQ/CRP. Finally, identified cytokines were proved to be significantly involved in focal adhesion, PI3K/AKT, and MAPK signaling pathways, and regulation of cell development, localization, proliferation, migration, differentiation, immune system processes, and stress response. Obtained results confirm the key function of the BM microenvironment in the pathogenesis of MM and indicate the essential role of numerous cytokines in disease progression and EMD development. However, the exact mechanisms need to be further clarified.

Real-world evidence of efficacy and safety of pomalidomide and dexamethasone in relapsed/refractory multiple myeloma patients: Czech registry data.

We assessed the outcomes of pomalidomide and dexamethasone treatment in relapsed/refractory multiple myeloma (RRMM) patients with ≥1 prior line of therapy. We analyzed the data of all RRMM patients treated with pomalidomide and dexamethasone at nine Czech centers between 2013 and 2018. The source of the data was the Registry of Monoclonal Gammopathies of the Czech Republic. Primary endpoints included response rates based on International Myeloma Working Group criteria and survival measures, including progression-free survival (PFS) and overall survival (OS). Secondary endpoints were toxicities and previous treatment patterns, including refractory to lenalidomide, and their impact on final outcomes. The overall response rate was 51.8% and the clinical benefit rate (including patients with minimal response) was 67.1%, with 0.6% of complete responses, 8.5% of very good partial responses, and 42.1% of partial responses (PR). Overall, 16.5% of patients had a minimal response, and 32.3% had stable disease /progression. Median PFS was 8.8 months and the median OS was 14.2 months. In patients who achieved ≥PR, the median PFS and OS were significantly longer compared to non-responders (median PFS (12.1 vs. 4.5 months, p≤0.001 respectively), median OS (22.1 vs. 7.7 months, p≤0.001, respectively). The most frequent adverse events (AEs) were neutropenia (29.9%) and anemia (18.9%), non-hematological AEs included infections (14.6%) and fatigue (7.3%). Our analysis confirmed the effectiveness of pomalidomide and dexamethasone in a real-world setting. This therapy achieved reasonable outcomes comparable to the data from clinical trials even though this was an unbiased cohort of patients.

Identification of patients at high risk of secondary extramedullary multiple myeloma development.

Multiple myeloma (MM) is characterized by malignant plasma cell infiltration of the bone marrow. In extramedullary multiple myeloma (EMD), a subclone of these cells migrates out of the bone marrow. Out of 4 985 MM patients diagnosed between 2005 and 2017 in the Czech Republic, we analyzed 234 secondary EMD patients to clarify risk factors of secondary EMD development. We found younger age [<65 years; odds ratio (OR) 4·38, 95% confidence interval (CI): 2·46-7·80, P < 0·0001], high lactate dehydrogenase (LDH) levels (>5 µkat/l; OR 2·07, 95% CI: 1·51-2·84, P < 0·0001), extensive osteolytic activity (OR 2·21, 95% CI: 1·54-3·15, P < 0·001), and immunoglobulin A (IgA; OR 1·53, 95% CI: 1·11-2·11, P = 0·009) or the non-secretory type of MM (OR 2·83; 95% CI: 1·32-6·04, P = 0·007) at the time of MM diagnosis to be the main risk factors for secondary EMD development. Newly diagnosed MM (NDMM) patients with subsequent EMD had inferior median progression-free (PFS) and overall (OS) survival when compared to NDMM patients without future EMD [mPFS: 13·8 months (95% CI: 11·4-16·3) vs 18·8 months (95% CI: 17·7-19·9), P = 0·006; mOS: 26·7 months (95% CI: 18·1-35·4) vs 58·7 months (95% CI: 54·8-62·6), P < 0·001]. We found that NDMM patients with specific risk factors associated with secondary EMD development have a more aggressive disease course before secondary EMD develops.

LncRNAs LY86-AS1 and VIM-AS1 Distinguish Plasma Cell Leukemia Patients from Multiple Myeloma Patients.

Long non-coding RNAs (lncRNAs) are functional RNAs longer than 200 nucleotides. Due to modern genomic techniques, the involvement of lncRNAs in tumorigenesis has been revealed; however, information concerning lncRNA interplay in multiple myeloma (MM) and plasma cell leukemia (PCL) is virtually absent. Herein, we aimed to identify the lncRNAs involved in MM to PCL progression. We investigated representative datasets of MM and PCL patients using next-generation sequencing. In total, 13 deregulated lncRNAs (p < 0.00025) were identified; four of them were chosen for further validation in an independent set of MM and PCL patients by RT-qPCR. The obtained results proved the significant downregulation of lymphocyte antigen antisense RNA 1 (LY86-AS1) and VIM antisense RNA 1 (VIM-AS1) in PCL compared to MM. Importantly, these two lncRNAs could be involved in the progression of MM into PCL; thus, they could serve as promising novel biomarkers of MM progression.

Necessity of flow cytometry assessment of circulating plasma cells and its connection with clinical characteristics of primary and secondary plasma cell leukaemia.

Plasma cell leukaemia (PCL) is a rare and very aggressive plasma cell disorder. Preventing a dismal outcome of PCL requires early diagnosis with appropriate analytical tools. Therefore, the investigation of 33 patients with primary and secondary PCL was done when the quantity of circulating plasma cells (PCs) using flow cytometry (FC) and morphology assessment was evaluated. The phenotypic profile of the PCs was also analysed to determine if there is an association with clinical outcomes and to evaluate the prognostic value of analysed markers. Our results revealed that FC is an excellent method for identifying circulating PCs as a significantly higher number was identified by FC than by morphology (26·7% vs. 13·5%, P = 0·02). None of secondary PCL cases expressed CD19 or CD20. A low level of expression with similar positivity of CD27, CD28, CD81 and CD117 was found in both PCL groups. A decrease of CD44 expression was detected only in secondary PCL. Expression of CD56 was present in more than half of PCL cases as well as cytoplasmic nestin. A decreased level of platelets, Eastern Cooperative Oncology Group score of 2-3 and lack of CD20+ PC were associated with a higher risk of death. FC could be incorporated in PCL diagnostics not only to determine the number of circulating PCs, but also to assess their phenotype profile and this information should be useful in patients' diagnosis and possible prognosis.

Outcome of COVID-19 infection in 50 multiple myeloma patients treated with novel drugs: single-center experience.

Infections are the primary cause of morbidity and mortality in multiple myeloma (MM) patients (pts). The aim of our retrospective analysis was to evaluate incidence and course of COVID-19 infection in a cohort of 351 MM outpatients treated with novel drugs. COVID-19 disease was detected in 50/351 pts (14%); median age was 68 years. Gender, ISS stage, and last treatment lines were as follows: male 32, female 18; ISS-I 19, ISS-II 20, ISS-III 11; daratumumab-based 15, lenalidomide-based 12, bortezomib-based 17, other 6. Positive PCR test at COVID-19 diagnosis was present in all pts; anti-myeloma treatment was interrupted. Hospitalizations for COVID-19 pneumonia were necessary for 28/50 pts (56%), 18/50 pts (36%) in standard unit (SU) 10/50 pts (20%) in intensive care unit (ICU), and 9/50 pts (18%) died. The statistically significant parameters for COVID-19 hospitalization were as follows: responsive versus non-responsive disease (p = 0.027), ECOG performance status 0-2 versus ≥ 3 (p = 0.014), presence of comorbidities (0-1 versus ≥ 2, p = 0.043). The statistically significant factors for COVID-19 death were as follows: ECOG 0-2 versus ≥ 3 (p = 0.001), presence of comorbidities (0-1 versus ≥ 2, p = 0.007), serious course of COVID-19 disease with ICU hospitalization (SU versus ICU, p = 0.001). None of the other studied risk factors was associated with poor outcome (age, gender, ISS stage, immunoparesis, type of anti-myeloma treatment). Full recovery from COVID-19 infection was observed in 41/50 pts (82%) in median of 32 days. The course of COVID-19 disease in MM pts was mostly moderate or serious with 56% of hospitalizations and 18% of deaths.

Bortezomib-based therapy for newly diagnosed multiple myeloma patients ineligible for autologous stem cell transplantation: Czech Registry Data.

OBJECTIVES: This study compared the use of bortezomib in different combination regimens in newly diagnosed multiple myeloma (NDMM) patients who were transplant ineligible. PATIENTS AND METHODS: We analyzed data from the Registry of Monoclonal Gammopathies (RMG) of the Czech Myeloma Group (CMG) to provide real-world evidence of outcome for 794 newly diagnosed MM transplant ineligible patients. The most frequently used regimen was VCd (bortezomib-cyclophosphamide-dexamethasone) (47.5%) over VMP (bortezomib-melphalan-prednisone) (21.7%), BDd (bortezomib-doxorubicin-dexamethasone) (9.8%), and VTd (bortezomib-thalidomide-dexamethasone) (2.9%). RESULTS: The overall response rate (ORR) was 69.2% (478/691), including 12.6% (≥ CR); 34.7% very good partial responses (VGPR); and 21.9% partial responses (PR). Among triplet regimens, VMP was the most effective regimen compared to VCd, BDd, and VTd. Median PFS was 22.3 vs. 18.5 vs. 13.7 vs. 13.8 mo, (P = .275), respectively, and median OS was 49 vs. 41.7 vs. 37.9 vs. 32.2 mo (P = .004), respectively. The most common grade 3-4 toxicities were anemia in 17.4% and infections in 18% of patients. CONCLUSION: Our study confirmed that bortezomib-based treatment is effective and safe in NDMM transplant ineligible patients, especially VMP, which was identified as superior between bortezomib-based induction regimens not only in clinical trials, but also in real clinical practice.

Transformation of IgM-MGUS into Waldenström´s macroglobulinemia in two of six patients treated for Schnitzler´s syndrome.

Transformation of IgM-MGUS into Waldenström´s macroglobulinemia in two of six patients treated for Schnitzler´s syndrome Schnitzler´s syndrome is a very rare, adult-onset, apparently acquired autoinflammatory disease. Chronic urticarial rash and symptoms of systemic inflammation including fever, arthralgia and bone pain with the presence of monoclonal immunoglobulin M (IgM), rarely IgG, are among hallmarks of the disease. We performed a retrospective study of 6 patients (5 men, 1 woman) diagnosed with Schnitzler´s syndrome fulfilling the Strasbourg criteria who had been treated at our centre in the University Hospital Brno from 2007 to 2021. Median age at diagnosis was 54 (45-67) years, median follow up was 8 (3-14) years. All 6 patients had IgM κ monoclonal gammopathy, increased CRP and/or erythrocyte sedimentation rate and arthralgia or bone pain, 4 patients suffered from fever, three had leucocytosis 10 × 109/L and lymphadenopathy was found in one patient. 18FDG-PET/CT scan with low-dose total body CT became a part of the initial baseline assessment in 5 patients with suspected Schnitzler´s syndrome, while Na18F-PET/CT was used in one patient to confirm the presence of osteosclerotic leasions as a criterion of the disease. All patients had osteosclerotic or hyperostotic bone lesions detected by low-dose CT examination, with increased 18FDG uptake in illiac and femoral bone marrow. The patient with Na18F-PET/CT scan revealed intensive abnormal tracer uptake with Na18F-PET/CT being more sensitive for detection of osteosclerotic lesions in Schnitzler´s syndrome than 18FDG-PET/CT. All patients were treated with daily subcutaneous anakinra without any adverse events, with excellent clinical results. We observed complete disappearance of urticaria and other symptoms persisting during years of anakinra administration. IgM-MGUS transformed into Waldenström´s macroglobulinemia in two of six patients, but only one patient developed symptoms requiring RBD (Rituximab, Bendamustin, and Dexamethasone) treatment, which induced almost complete remission of the disease. Successful RBD therapy enabled to prolong intervals of maintenance anakinra from 24 to 48 hours with almost complete control of urticarial rash and other symptoms. We suggest close monitoring of patients with Schnitzler´s syndrome to early capture potential transformation into Waldenström´s macroglobulinemia with succesful treatment of both conditions.

Therapy of 3 patients with Erdhiem-Chester disease with cladribin or cladribin in combination with cyclophosphamide. Case report and review of the therapy.

Three adult patients with confirmed Erdheim-Chester disease (ECD) are followed at our department. Cladribine in monotherapy or in combination with cyclophosphamide were used for first line therapy. The median number of cycles of cladribine or cladribine and cyclophosphamide was 7 (range 6-8). In two cases complete response was achieved, in one case this therapy achieved no response. The duration of response is in one case 11 years, in second case the follow up is too short for evaluation of response duration. In case of no-response to cladribine and cyclophosphamide stabilisation of disease was achieved with anakinra. The tolerance was good without any toxicity grade II and higher. Cladribin and cyclophosphamide is one option for treatment of Erdheim-Chester disease.

Epigenetic Regulation of MicroRNA Clusters and Families during Tumor Development.

MicroRNAs are small non-coding single-stranded RNA molecules regulating gene expression on a post-transcriptional level based on the seed sequence similarity. They are frequently clustered; thus, they are either simultaneously transcribed into a single polycistronic transcript or they may be transcribed independently. Importantly, microRNA families that contain the same seed region and thus target related signaling proteins, may be localized in one or more clusters, which are in a close relationship. MicroRNAs are involved in basic physiological processes, and their deregulation is associated with the origin of various pathologies, including solid tumors or hematologic malignancies. Recently, the interplay between the expression of microRNA clusters and families and epigenetic machinery was described, indicating aberrant DNA methylation or histone modifications as major mechanisms responsible for microRNA deregulation during cancerogenesis. In this review, the most studied microRNA clusters and families affected by hyper- or hypomethylation as well as by histone modifications are presented with the focus on particular mechanisms. Finally, the diagnostic and prognostic potential of microRNA clusters and families is discussed together with technologies currently used for epigenetic-based cancer therapies.