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Abstract Juvenile myelomonocytic leukemia (JMML) is a rare myeloproliferative disease of early childhood that develops due to mutations in the genes of the RAS-signaling pathway. Next-generation high throughput sequencing (NGS) enables identification of various secondary molecular genetic events that can facilitate JMML progression and transformation into secondary acute myeloid leukemia (sAML). The methods of single-cell DNA sequencing (scDNA-seq) enable overcoming limitations of bulk NGS and exploring genetic heterogeneity at the level of individual cells, which can help in a better understanding of the mechanisms leading to JMML progression and provide an opportunity to evaluate the response of leukemia to therapy. In the present work, we applied a two-step droplet microfluidics approach to detect DNA alterations among thousands of single cells and to analyze clonal dynamics in two JMML patients with sAML transformation before and after hematopoietic stem cell transplantation (HSCT). At the time of diagnosis both of our patients harbored only “canonical” mutations in the RAS signaling pathway genes detected by targeted DNA sequencing. Analysis of samples from the time of transformation JMML to sAML revealed additional genetic events that are potential drivers for disease progression in both patients. ScDNA-seq was able to measure of chimerism level and detect a residual tumor clone in the second patient after HSCT (sensitivity of less than 0.1% tumor cells). The data obtained demonstrate the value of scDNA-seq to assess the clonal evolution of JMML to sAML, response to therapy and engraftment monitoring.

Background: To date, fewer than 20 patients have been identified as having germline biallelic mutations in the coronin-1A gene (CORO1A) and its protein with clinical features of combined immunodeficiency characterized by T-cell lymphopenia ranging from the severe phenotype to the mild phenotype, recurrent infections, and lymphoproliferative disorders. However, the effects of CORO1A protein disruption on actin-dependent functions in primary cells have not been fully delineated. Objective: We sought to characterize the underlying defects of actin-dependent cellular functions in a female patient with combined immunodeficiency caused by a novel missense variant in the CORO1A gene in combination with a de novo heterozygous microdeletion of chromosome 16p11.2 and also to provide evidence of the pathogenicity of this gene mutation. Methods: To identify the genetic defect, next-generation sequencing followed by Sanger confirmation and array comparative genomic hybridization were performed. Western blot and quantitative PCR tests were used to assess the effects on the protein. Flow cytometry and live microscopy were performed to investigate cellular motility and immune cell counts and function. Results: We demonstrated that the CORO1A hemizygous variant c.19C>T, p. A7C induces significant decreases in cellular levels of the CORO1A protein while leaving mRNA concentrations unaffected. The observed mutation resulted in impaired natural killer cell cytotoxicity and platelet calcium signaling. In addition, primary granulocytes and mesenchymal cells showed significant defects in motility. Conclusion: Collectively, we added new data about the CORO1A gene as a key player in actin cytoskeleton dynamics and cell signaling. Our findings expand the clinical spectrum regarding CORO1A protein deficiency and confirm the importance of a personalized therapeutic approach for each patient.

The use of all-trans retinoic acid (ATRA) drastically improved the results of therapy for acute promyelocytic leukeimia (APL). The high efficiency of the Russian protocol APL-93—98 applied to 62 children and adolescents with APL (event-free and overall survival (EFS and OS) were 84±5% respectively with a relapse rate of 7%) was achieved, by administering the high cumulative dose of daunoruicin (495 mg/m2) and single doses of АТRА (45 mg/m2). In this connection, the APL-2003 protocol attempted to reduce both acute and chronic toxicity of the therapy, by decreasing the cumulative dose of daunorubicin to 405 mg/m2 and the single dose of АТRА to 25 mg/m2 under regular control of minimal residual disease via molecular monitoring of the specific transcript PML/RARα. Analysis of the results of treatment in 61 patients aged 1.3 to 17 years (median 11.3) showed that despite of the reduced protocol intensity, the efficiency of therapy did not generally reduce — EFS and OS were 79±6 and 93±3%, respectively. The likelihood of the development of a relapse was significantly affected by molecular resistance, i.e. the retention of the transcript PML/RARα before a phase of maintenance therapy: the recurrence risk in this group was 57% whereas there were no differences in all cure rates between the patients depending on baseline leukocytosis. All 6 patients with relapses were treated with arsenic trioxide, resulting in not only clinical and hematological, but also molecular remissions; thereafter the patients received myeloablative therapy and autologous hemopoietic stem cell transplantation. The second remission lasted 3 to 24 months. Thus, reducing the cumulative dose of anthracyclines and the dose of АТRА did not make the results of the therapy for APL worse. The monitoring of minimal residual disease before and during maintenance therapy is a mandatory component of successful treatment in APL patients. Arsenic trioxide is an effective agent for the treatment of APL relapses.

Standard therapy of high risk patients with Langerhans cell histiocytosis (LCH) is associated with essential risk of therapy failure. In the present study results of 2-clorodeoxyadenosine usage as alternative therapy in this group of patients are analyzed. In this study 31 patients with multisystem form LCH with involving of organs at risk were included. Nineteen patients have received Prednisone and Vinblastine as front line therapy (standard group). Nine patients have received therapy with 2-CdA and cytosine-arabinoside (group 2-CdA). The patients in standard group statistically significant more often (55.5 % vs. 0 %, р = 0.0095) required second line therapy. Permanent disease conse-quences was more often developed in standard group (63.6 % vs. 0 %, р = 0.0147). The overall survival was 65.7 ± 12,8 % among standard group patients and 88.8% ±10% in 2-CdA group; p = 0.27. The event-free survival was in standard group 33.9 ± 12 %, in 2-CdA group – 88.8 ± 10 %, p = 0.0207. Severe hematological toxicity was observed at 2-CdA therapy. 2-CdA therapy is highly effective in treatment of high risk patients with LCH. The drug should be used only in a specialized hospital.

Protocol AML-MM-2000 treatment results of unfavorable prognostic group in children with primary acute myeloid leukemia (AML) in Russia and Belarus are presented. 105 children at the age from 2 weeks till 18 years (a median age — 10.8 years) are included in the study. In 91 patients (86.7%) hematological remission have reached, from them 34 patients (37.4%) are in the first continuous complete remission (CCR). 6-years overall survival (OS), event-free survival (EFS) and relapse-free survival (RFS) rate for all group of patients was 0.35 ±} 0.05; 0.32 ±} 0.04 and 0.43 ±} 0.05, respectively. Survival analysis of children with different cytogenetic anomalies has allowed to define two prognostic groups of patients: the intermediate prognosis, including patients with normal kariotype and t(9;11) which EFS and RFS rate was 40—50%, and unfavorable prognosis with EFS and RFS rate less than 40%. The efficiency analysis of three postremission therapy type (allogeneic and autological hematopoietic stem cells transplantation (HSCT) and chemotherapy (HT)) in intermediate and unfavorable prognostis groups was carried out. High efficiency of related HLA-identical HSCT in patients both intermediate and unfavorable prognostis groups have been shown. Autological HSCT is possible in intermediate prognosis patients with absence of HLA-identical siblings and in unfavorable prognosis patients with absence of HLA-identical unrelated donor.

Prognosis of patients with juvenile myelomonocytic leukemia not undergoing allogeneic hematopoietic cells transplantation (SCT) is dismal and not affected by any cytotoxic chemotherapy. Differentiating therapy is an attractive approach in JMML, due to ability of JMML cells to differentiate and die under influence of treatment with various agents in vitro. We report results of first-line treatment of 14 patients with JMML with 13-cis retinoic acid (RA) 100 mg/m2 daily peroral intake and low dose Ara-C - 25 mg/m2 daily for 10 days monthly. Complete remission (CR) or hematological improvement (HI) was obtained in 7 patients (50%). Four patients (median age at disease manifestation 5 months, median level of HbF —6,2%) achieved CR after a median of 9 cycles of therapy; in 3 patients the best response was HI (age at disease manifestation - 5; 7 and 46 months, HbF — 4,2; 8,0 and 51,7%) after 2; 3 and 5 cycles. Three out of 4 patients with CR are alive and have been in CR for 10; 17 and 30 months after start of therapy, acute lymphoblastic leukemia developed in one patient after 84 months of CR. Two patients with HI are still receiving treatment and have been in stable condition for 10 months after the initiating therapy, while 1 patient died after 8 months of therapy from catheter-related sepsis. The progression of the disease despite the treatment was registered in 7 patients (median age at disease manifestation 16,3 months, median HbF — 35,4%). We conclude that 13-cis RA in combination with low dose AraC may be useful in the treatment of patients younger than 1 year with low level of HbF, although the general paradigm of treatment of JMML with SCT remains unchanged.

Introduction of biosimilars in clinical practice results in substantial reduction of direct medical costs. However, limited data concerning safety and tolerance of biosimilars exist, especially in children. We conducted double blind randomized trial comparing immediate tolerance of locally manufactured filgrastim (LeucostimR, “Biocad”, Russia) with original formulation (“Neupogen”, “Roche”, Switzerland) in children with various hematologic and oncologic diseases. Ten patients (4 F; 6 M) with a median age of 9.5 y (range 5—16 y) in whom G-CSF was indicated either by protocol or clinically were included into the study. All patients were scheduled to receive both formulations of G-CSF in order determined by randomization with permuted blocks. Pain was assessed with visual analog scale, ranging sensation of pain from 0 to 10 points. There were 41 injections of LeucostimR and 39 of Neupogen, and а median number of points attributed was 1.134 (0—10), and 1.661 (0—9) respectively (p=0,669). Intrapatient pain scores were quite consistent and did not differ by more than 1 point between any two injections. Other immediate toxicities were negligible or inexistent. Our study clearly demonstrates that both formulation of filgrastim are equally well tolerated.

Early T-cell precursor acute lymphoblastic leukemia (ETP-ALL) develops from very early cells with the potential for both T-cell and myeloid differentiation. The ambiguous nature of leukemic blasts in ETP-ALL may lead to immunophenotypic alterations at relapse. Here, we address immunophenotypic alterations and related classification issues, as well as genetic features of relapsed pediatric ETP-ALL. Between 2017 and 2022, 7518 patients were diagnosed with acute leukemia (AL). In addition to conventional immunophenotyping, karyotyping, and FISH studies, we performed next-generation sequencing of the T-cell receptor clonal repertoire and reverse transcription PCR and RNA sequencing for patients with ETP-ALL at both initial diagnosis and relapse. Among a total of 534 patients diagnosed with T-cell ALL (7.1%), 60 had ETP-ALL (11.2%). Ten patients with ETP-ALL experienced relapse or progression on therapy (16.7%), with a median time to event of 5 months (ranging from two weeks to 5 years). Most relapses were classified as AL of ambiguous lineage (n = 5) and acute myeloid leukemia (AML) (n = 4). Major genetic markers of leukemic cells remained unchanged at relapse. Of the patients with relapse, four had polyclonal leukemic populations and a relapse with AML or bilineal mixed-phenotype AL (MPAL). Three patients had clonal TRD rearrangements and relapse with AML, undifferentiated AL, or retention of the ETP-ALL phenotype. ETP-ALL relapse requires careful clinical and laboratory diagnosis. Treatment decisions should rely mainly on initial examination data, taking into account both immunophenotypic and molecular/genetic characteristics.

Donor lymphocyte infusion has been used in the management of relapsed hematologic malignancies after allogeneic hematopoietic cell transplantation. It can eradicate minimal residual disease or be used to rescue a hematologic relapse, being able to induce durable remissions in a subset of patients. With the increased use of haploidentical hematopoietic cell transplantation, there is renewed interest in the use of donor lymphocytes to either treat or prevent disease relapse post transplant. Published retrospective and small prospective studies have shown encouraging results with therapeutic donor lymphocyte infusion in different haploidentical transplantation platforms. In this consensus paper, finalized on behalf of the Acute Leukemia Working Party of the European Society for Blood and Marrow Transplantation, we summarize the available evidence on the use of donor lymphocyte infusion from haploidentical donor, and provide recommendations on its therapeutic, pre-emptive and prophylactic use in clinical practice.

Abstract Tumor-derived extracellular vesicles (EVs) are active contributors in metastasis and immunosuppression in tumor microenvironment. At least some of the EVs carry tumor surface molecules such as tumor-associated antigens (TAAs) and/or checkpoint inhibitors, and potentially could interact with T cells or CAR T cells. Upon contact with T cells, EVs could alter their phenotype and functions by triggering signaling through TCR or CAR reprogramming them to escape immune response. We hypothesize that EVs that possess TAA on the surface will probably interact with CAR T cells which can recognize and bind corresponding TAA. This interaction between EVs and CAR T cells may change the outcome of CAR T-based cancer immunotherapy since it should affect CAR T cells. Also, EVs could serve as adjuvants and antigenic components of antitumor vaccines. Herein, we isolated EVs from B cell precursor leukemia cell line (pre-B ALL) Nalm-6 and demonstrated that recognition and binding of CD19+EVs with CD19-CAR T cells strongly depends on the presence of CD19 antigen. CD19+EVs induce secretion of pro-inflammatory cytokines (IL-2 and IFN-y) and upregulated transcription of activation-related genes (IFNG, IFNGR1, FASLG, IL2) in CD19-CAR T cells. Tumor necrosis factor receptor superfamily (TNFRSF4 and TNFRSF9) and T-cell exhaustion markers (CTLA4, LAG3, TIM3 and PDCD1LG2) were also upregulated in CD19-CAR T cells after incubation with CD19+EVs. Long-term cultivation of CD19+ or PD-L1+EVs with CD19-CAR T cells led to increased terminal differentiation and functional exhaustion according to elevated expression of PD-1, TIGIT, CD57. In summary, our results suggest that chronic exposure of CD19-CAR T cells to CD19+EVs mediates activation and systemic exhaustion in antigen-specific manner, and this negative effect is accompanied by the impaired cytotoxic activity in vitro.

Some recommendations of Infectious Diseases Society of America for diagnosis and treatment of invasive aspergillosis with lung involvement, which is the most frequent clinical manifestation of aspergillar infection.Full version of recommendations was published in one of the editions of journal “Clinical microbiology and antibacterial chemotherapy” (2008. Т. 10. №2). Fungi of Aspergillus kin is the main etiologic cause of life-threatening infections in immunocompromised patients, such as patients with prolonged neutropenia, advanced stages of HIV infection, hereditary immunodeficiency states and after allogeneic hematopoietic stem cell transplantation (allo-HSCT) and/or lung transplantation. This version of recommendations for treatment of invasive aspergillosis from IDSA (Infectious Diseases Society of America) substituted the former recommendations published in 2000. The level of evidence of treatment data is given in according with standard scheme used in the IDSA guidance.

Epstein–Barr virus (EBV) is a member of herpes-viruses family. Now it is well-known, that it can be a cause of wide spectrum lymphoproliferative disoders. The given problem is especially serious after hematopoietic stem cells transplantation (HSCT); frequency of death linked to this complication can achieve 50–90 %. Risk factors for development of posttransplant lymphoproliferative syndromes (PTLS) are: using partially compatible graft, T-cell depletion, presence of severe acute graft-versus-host reaction (GVHD), using of antitymocytic globulin, etc. Severity of associated with EBV posttransplant complications and problems relate to absence of clear diagnostic algorithm, PTLS prophylactic and therapy schedule are argument for necessity of the further studies.

New guidelines on diagnosis and treatment of a primary immune thrombocytopenia (ITP) in children and adults, on the basis of modern pathogenesis conceptions and considering possibilities of hematological practice in Russia are presented. Guidelines are based on a consensus of international and Russian experts on ITP. Diagnostic features of ITP are noted and various I, II and III lines treatment, including new effective medical products which have recently appeared in Russia, in particular, trombopoietin receptor agonists (romiplostim, eltrombopag), considerably expanded conservative treatment possibilities are offered. The presented guidelines can help hematologists to develop individual schedule for each given patients with ITP and to improve patients quality of life.

Various conditioning regimes influence on sexual development and gonads function in children and adolescent after stem cell transplantation was studied. 45 patients were enrolled in the study: 23 patients with aplastic anemia (АА), who received non-myeloablative conditioning, and 22 patients with acute myeloid leukemia (AML) after myeloablative conditioning. Sexual development was estimated by Tanner classification, laboratory tests included gonadotropic hormones, sex steroids, antiMullerian hormone and inhibin B level detection. It has been shown that non-myeloablative conditioning does not influence sexual development in any patients. Extremely high frequency of gonads lesion in patients received myeloablative conditioning was registered: hypergonadotrophic hypogonadism in 8 from 12 girls with severe decrease of ovaries functional reserve in all patients; germinal epithelium lesion in 9 from 10 boys.

Early complications of hematopoietic stem cell transplantation (HSCT) of vascular origin within the first 30-60 days after HSCT, which are resulting from endothelial injury, are an important cause of transplant-associated morbidity and mortality. Authors describe a case report serving as an example of several endothelial syndromes development with overlapping clinical features. Risk factors and therapy approaches of these complications are discussed.

Chronic immune thrombocytopenic purpura (ITP) is one of the most frequent immune hematological disorders in which development the leading part is played by the antibodies directed against a narrow spectrum of platelet antigens. Though death rate at chronic ITP is insignificant, no more than 1%; disease strongly reduces patients quality of a life, and frequently requires difficult and expensive treatment. Antiplatelets antibodies mediating ITP, are directed against glycoprotein GP IIb/IIIa and, less often, GP Ib/IX. At ITP can be registered both raised bone marrow platelet production and accelerated peripheral blood platelet clearance, and strongly decreased production and normal platelet life-span. Antibodies to platelet membrane glycoproteins directly disturb platelet production in bone marrow. Standard drug interventions at chronic ITP - glucocorticoids in various doses, high doses intravenous immunoglobulin, anti-D immunoglobulin, rituximab - rare lead to stable increase platelet number while in 2/3 patients splenectomy is effective. The new therapy approach in chronic ITP is stimulation of platelet production in bone marrow. Recombinant fusion protein Romiplostim stimulates trombopoietin receptor and it is effective at long-term therapy in 87% patients with chronic ITP irrespective of previous splenectomy. TPO antibodies development with romiplostim therapy was not revealed.

Prognosis of patients with acute myeloid leukemia receiving intensive chemotherapy is defined as kariotyping anomalies, and mutations of genes responsible for surviving and self-maintenance leukemic cells. In the giving work incidence of mutation involving genes FLT3, c-KIT, NPM1 having prognostic value in adults is analysed. Kynase domain FLT3 mutation in 18 from 83 patients (21.6%) was detected. 2 from 18 patients (11%) achieved complete remission, 5 from 18 patients (27.7%) with FLT3 mutations were refractory to therapy, two patients died from treatment complications, 9 from 18 (50%) relapsed. Only 2 patients (11%) are alive in continuous complete remission. с-KIT mutations detected in 14.2% (2/14 patients), and NPM1 mutations represented allelic polymorphism. Thus, kynase domain FLT3 mutation are prognostic unfavorable.

Therapy results of 61 patients (children and adolescents, 2—17 years of age; a median — 8.76 years) with B-cells non-Hodgkin lymphomas III—IV stage and B-cell acute leukemia (B-NHL/B-ALL), treating according to protocol with polichemotherapy and monoclonal antibodies against B-cell receptor CD20 — rituximab (Mabthera, Hoffmann La Roche) applications, are presented. The protocol consist of cytoreductive phase and 6 polychemotherapy courses, similar to original protocol B-NHL-BFM 90, with exception of decreasing methotrexate dosage in 2 first courses from 5 to 1 g/m2/24 hours. Rituximab — 375 mg/m2 IV — in Day 0 first 4 courses was given.Four patients have died within first 3 weeks of therapy, 2 were primary refractory patients and 55 patients have achieved complete remissions. There was no case of remission death; relapse has developed only at one patient (neuroleukemia in patient with Burkitt lymphoma). 54 patients (88%) are in continuous complete remission. Overall and event-free survival rate were 0,90±0,04 with median follow-up after therapy ending 34 months (12—53 months). Authors discuss tactics of such combined therapy, features of remission registration, considering that at third of patients, residual mass was long-term detected, and for which assessment besides CT/MRT a positron-emission tomography (PET) and/or a repeated biopsy were done. Also it is possible to conclude that with use of target therapy chemotherapy intensity of such tumors can be reduced. Authors concluded that in cases of target therapy efficacy criteria should be modified, and it is necessary to use as much as possible informative technique to remission control (PET, minimal residual disease assessment with use of molecular-genetic methods).

Cytomegalovirus infection (CMV) is an extremely serious problem in patients after hematopoietic stem cells transplantation (HSCT). We have evaluated importance of major risk factors CMV development in patients after allogeneic HSCT (n = 168) from related (n = 56), unrelated (n = 90) or haploidentical donors (n = 22). Clinical importance of HSCT type as risk factors CMV development was shown; patients after unrelated or haploidentical HSCT had the worst prognosis. We also demonstrated that ≥ 2 grade acute GVHD statistically significant increase CMV reactivation probability after any types of HSCT. Comparison of infection reactivation frequency and event-free survival between subgroups of patients, received HSCT from CMV-positive and CMV-negative donors, absence of any differences was revealed. In the second group CMV infection was more severe. Preventive gancyclovir treatment has not shown efficacy and any influence on frequency of CMV reactivation.

Studies on platelet function in children older than neonatal period are few and their results are controversial. The pediatric platelets were alternatively reported to be more active or less active than adults’ ones. We compared platelet function in the several age groups of children to adults and evaluated the age when platelet function reaches the adults’ status. The study included 76 healthy children and 49 healthy adult volunteers. Types of platelet activation used included: collagen-related peptide (CRP) and PAR-1 activating peptide SFLLRN; SFLLRN, PAR-4 activating peptide AYPGKF and adenosine diphosphate (ADP); ADP. The parameters determined included forward (FSC) and side scatter (SSC), CD42b, CD61, CD62P, PAC-1, annexin V binding and mepacrine release levels. Resting pediatric platelets were similar to adults’ platelets except for 1.2-fold decreased FSC and dense granules volume in youngest children, and 2.5-fold increased annexin V level in children aged 1–10 years. After CRP+SFLLRN stimulation, pediatric platelets had a 1.2-fold lower alpha- and 1.1-fold lower dense granule release than adults. For SFLLRN+AYPGKF+ADP stimulation, this was observed only for youngest children. The response to ADP stimulation was identical for pediatric platelets and adults. Pediatric platelets have lower granular release than adults’ platelets, which persists until the age of 18.

Survival after allogeneic hematopoietic stem cell transplantation (allo-HSCT) for severe idiopathic aplastic anemia (SAA) has improved in recent years, approaching 75% at 5 years. However, an SAA-adapted composite endpoint, graft-versus-host disease (GvHD) and relapse/rejection-free survival (GRFS), may more accurately assess patient outcomes beyond survival. We analyzed GRFS to identify risk factors and specific causes of GRFS failure. Our retrospective analysis from the Severe Aplastic Anemia Working Party of the European Society for Blood and Marrow Transplantation included 479 patients with idiopathic SAA who underwent allo-HSCT in two conventional situations: i) upfront allo-HSCT from a matched related donor (MRD) (upfront cohort), and ii) allo-HSCT for relapsed or refractory SAA (rel/ref cohort). Relevant events for GRFS calculation included graft failure, grade 3-4 acute GvHD, extensive chronic GvHD, and death. In the upfront cohort (n=209), 5-year GRFS was 77%. Late allo-HSCT (i.e., >6 months after SAA diagnosis) was the main poor prognostic factor, specifically increasing the risk of death as the cause of GRFS failure (hazard ratio [HR]=4.08; 95% confidence interval [CI]: 1.41-11.83; P=0.010). In the rel/ref cohort (n=270), 5-year GRFS was 61%. Age was the main factor significantly increasing the risk of death (HR=1.04; 95% CI: 1.02-1.06; P

Abstract The poor prognosis of acute T‐cell lymphoblastic leukemia (T‐ALL) and T‐cell lymphoblastic lymphoma (T‐LBL) in older adults and patients with relapsed/refractory illness is an unmet clinical need, as there is no defined standard of care and there are few treatment options. Abnormally elevated CD38 expression in T‐ALL and T‐LBL is associated with tumor expansion and disease development, making CD38 a potential target for anti‐T‐ALL and T‐LBL treatment. Isatuximab is a monoclonal antibody that binds to a specific epitope on CD38. The purpose of the study was to assess the efficacy and safety of isatuximab monotherapy in a phase 2, multicenter, one‐arm, open‐label study in patients with relapsed or refractory T‐ALL or T‐LBL (Clinical Trials.gov identifier NCT02999633). The primary endpoint was to assess the efficacy of isatuximab by overall response rate (ORR). An interim analysis based on the efficacy and safety of isatuximab in the first 19 patients enrolled was scheduled, however only 14 patients were enrolled in the study. No patient achieved complete response (CR) or CR with incomplete peripheral recovery. Most patients (11 [78.6%]) developed progressive disease and had progressive disease as their best response. A total of 10 (71.4%) patients had treatment emergent adverse events considered treatment‐related, with infusion reactions as the most frequent drug‐related TEAE, occurring in 8 (57.1%) patients. Despite the low efficacy of isatuximab in the current study, it is likely that the use of immunotherapy medication in T‐ALL will be expanded through logically targeted approaches, together with advances in the design of T‐cell therapy and clinical experience and will provide restorative options beyond chemotherapy and targeted treatments.

Simultaneous multilineage hematologic malignancies are uncommon and associated with poorer prognosis than single-lineage leukemia or lymphoma. Here, we describe a concomitant malignant neoplasm in a 4-year-old boy. The child presented with massive lymphoproliferative syndrome, nasal breathing difficulties, and snoring. Morphological, immunocytochemical, and flow cytometry diagnostics showed coexistence of acute myeloid leukemia (AML) and peripheral T-cell lymphoma (PTCL). Molecular examination revealed a rare t(9;9)(q34;q34)/SET::NUP214 translocation as well as common TCR clonal rearrangements in both the bone marrow and lymph nodes. The disease showed primary refractoriness to both lymphoid and myeloid high-dose chemotherapy as well as combined targeted therapy (trametinib + ruxolitinib). Hence, HSCT was performed, and the patient has since been in complete remission for over a year. This observation highlights the importance of molecular techniques for determining the united nature of complex SET::NUP214-positive malignant neoplasms arising from precursor cells with high lineage plasticity.

High-throughput sequencing of adaptive immune receptor repertoires is a valuable tool for receiving insights in adaptive immunity studies. Several powerful TCR/BCR repertoire reconstruction and analysis methods have been developed in the past decade. However, detecting and correcting the discrepancy between real and experimentally observed lymphocyte clone frequencies are still challenging. Here, we discovered a hallmark anomaly in the ratio between read count and clone count-based frequencies of non-functional clonotypes in multiplex PCR-based immune repertoires. Calculating this anomaly, we formulated a quantitative measure of V- and J-genes frequency bias driven by multiplex PCR during library preparation called Over Amplification Rate (OAR). Based on the OAR concept, we developed an original software for multiplex PCR-specific bias evaluation and correction named iROAR: immune Repertoire Over Amplification Removal (https://github.com/smiranast/iROAR). The iROAR algorithm was successfully tested on previously published TCR repertoires obtained using both 5’ RACE (Rapid Amplification of cDNA Ends)-based and multiplex PCR-based approaches and compared with a biological spike-in-based method for PCR bias evaluation. The developed approach can increase the accuracy and consistency of repertoires reconstructed by different methods making them more applicable for comparative analysis.

Background. Extramedullary infiltration (EI) is relatively common in children with acute myeloid leukemia (AML) (up to 20-25 %). However, its clinical and prognostic significance remains poorly understood.Objective: to describe clinical features and to define prognostic significance of EI in children with AML.Materials and methods. The subjects of retrospective observational study were 228 children with de novo AML. The median age was 6.6 years. All of them were treated according to the protocol AML-MM-2006 from April 2007 to June 2018.All patients with EI were divided into three cohorts according to the localization of the lesions: 1) central nervous system (CNS) involvement (CNS group), 2) other localizations apart from CNS (myelosarcomas (MS) group), 3) combined lesions (CNS + MS group).Results. EI was diagnosed in 84 patients (36.84 %) with de novo AML. Among them 47 (55.95 %) had CNS involvement, 20 (23.81 %) had MS, 15 (17.86 %) had both CNS involvement and MS. 5-year overall survival (OS) rate was slightly higher in patients with CNS involvement than in children without EI - 80 ± 12 % vs 71 ± 9 %, p = 0.26, however OS in patients with MS was significantly lower - 45 ± 16 % vs 71 ± 9 %, p