Vol 23, No 1 (2024)

   The bispecific monoclonal antibody blinatumomab (CD19/CD3) is widely and successfully used to treat children with relapsed/refractory B-cell precursor acute lymphoblastic leukemia (BCP-ALL). Advances have also led to the use of immunotherapy in children with primary BCP-ALL. This paper presents the effectiveness of a single blinatumomab course instead of consolidation chemotherapy and with short maintenance therapy in primary BCP-ALL patients. The study was approved by the Independent Ethics Committee and the Scientific Council of the Dmitry Rogachev National Medical Research Center of Pediatric Hematology, Oncology and Immunology. Between February 2020 and November 2022, 165 children with non-high-risk BCP-ALL (according to clinical stratification criteria defined in the study) were enrolled in the ALL-MB 2019 pilot study (NCT04723342). Patients received conventional risk-adapted induction therapy according to the ALL-MB 2015 protocol. Those who achieved complete morphological remission at the end of induction received 15 µg/m²/day of blinatumomab immediately after induction for 4 weeks, followed by 12 months of maintenance therapy. Minimal residual disease (MRD) was measured using multicolor flow cytometryat the end of induction, then immediately after blinatumomab course, and then four times during maintenance therapy at threemonth intervals. All 165 patients successfully completed induction therapy and achieved complete hematological remission. All had their MRD measured at the end of induction. One hundred thirty-six (82.2%) patients were MRD-negative, and the remaining 29 patients showed various levels of MRD positivity. MRD was assessed in all 164 patients who completed the blinatumomab course. One patient had blinatumomab discontinued due to acute neurotoxicity and was subsequently treated according to the intermediate-risk ALL-MB 2015 protocol. All but one patient achieved MRD negativity after blinatumomab course, regardless of MRD value at the end of induction. One adolescent girl with a high MRD level after induction remained MRD positive after blinatumomab course and further received high-risk therapy with allogeneic hematopoietic stem cell transplantation. At the time of analysis, 162 children had completed all therapy, including 12 months of maintenance. MRD was examined in 151 of them, and all were MRD negative. Over a 4-year study period with a median follow-up of 2.5 years, 10 relapses were registered: 4 in the standard-risk group and 6 in the intermediate-risk group. The 4-year event-free survival was 89.1 ± 3.7 % for all patients, 92.0 ± 4.2 % and 82.8 ± 8.1 % for the standard and intermediate risk groups, respectively. At the time of analysis, all patients were alive; no deaths were registered. Although the presented results are preliminary and more time is needed for definitive conclusions, a 4-week 15 µg/m²/day blinatumomab course immediately after induction followed by 12 months of maintenance therapy is effective in achieving and maintaining MRD negativity in children with non-high risk BCP-ALL. This study showed the fundamental possibility of treating ALL by combining immunotherapy with the bispecific monoclonal antibody blinatumomab with a significant chemotherapy reduction.

   Here, we report on a new treatment protocol for patients with BRAF-positive Langerhans cell histiocytosis (LCH). To achieve remission in the affected patients, we used vemurafenib (a targeted drug) in combination with cytarabine (Ara-C) and cladribine (2-CdA). The study included 27 patients: 18 children with multisystem LCH with risk organ involvement (RO+) and 9 – with multisystem LCH without risk organ involvement (RO–). The treatment started with a 28-day cycle of vemurafenib, with subsequent discontinuation. On Day 29, Аra-C + 2-СdA chemotherapy cycle № 1 was initiated. Vemurafenib treatment was again started on Day +1 after the Ara-C + 2-CdA cycle. The interval between the cycles was 28 days. Similarly, the next two Аra-C + 2-СdA chemotherapy cycles (№ 2 and № 3) were carried out. Then therapy with vemurafenib was stopped and 3 cycles of 2-CdA were administered. All the patients responded to the treatment quickly: on Day 28, disease activity score decreased from 15 to 2 in the RO+ group and from 4 to 0 in the RO– group. The two-year relapse-free survival in the RO+ group was 82 % (95 % confidence interval 66–100), and 89 % (95 % confidence interval 71–100) in the RO– patients. The overall survival in both groups was 100 %. Our study demonstrates the safety and effectiveness of the treatment with vemurafenib and intermediate-dose 2-CdA and Ara-C in children with multisystem RO+ and refractory LCH. This prospective non-randomized multicenter study was approved by the Independent Ethics Committee (Minutes No. 3e/1-18) and the Scientific Council of the Dmitry Rogachev National Medical Research Center of Pediatric Hematology, Oncology and Immunology of Ministry of Healthcare of the Russian Federation. It is registered at clinicaltrials.gov under the number NCT03585686. The first patient was enrolled on 22 June 2018, the data collection was stopped on 30 April 2023.

   Burkitt lymphoma (BL) is one of the most common types of non-Hodgkin lymphoma in children. The application of modern risk-adapted treatment regimens has resulted in 85–90 % survival rates in affected patients; however, prognosis still remains poor in case of relapsed/refractory disease. In standard protocols, patients were stratified into risk groups based primarily on disease stage and extent and lactate dehydrogenase levels. Mutations in the TP53 gene are associated with a poor prognosis in many tumors, and lately there have been reports that TP53 status may have prognostic value in pediatric BL. We analyzed therapy outcomes in patients treated in accordance with the B-NHL-2010M protocol according to their TP53 mutational status. We discovered that the 5-year event-free and overall survival rates in the patients with TP53 mutations were 45.3 % and 47.1 % respectively, versus 97.9% and 97.9% in those without TP53 mutations (p < 0.001). Hence, TP53 mutational status is an important prognostic marker in pediatric patients with BL and should be utilized in future protocols. The study was approved by the Independent Ethics Committee and the Scientific Council of the Dmitry Rogachev National Medical Research Center of Pediatric Hematology, Oncology and Immunology.

   The achievement of clinical and hematological remission at the end of induction therapy is one of the key treatment response parameters in pediatric acute myeloid leukemia (AML). Besides conventional cytomorphological evaluation of bone marrow (BM) blast count, minimal residual disease (MRD) measurement has been widely applied in routine clinical practice in recent years.

   The aim of the study was to compare the results of flow cytometric MRD evaluation with the results of cytomorphological BM investigation when assessing the achievement of remission at the end of induction in children with AML.

   The study was approved by the Independent Ethics Committee and the Scientific Council of the Dmitry Rogachev National Medical Research Center of Pediatric Hematology, Oncology and Immunology. We analyzed BM samples obtained from 402 children with AML, who had been treated according to the AML-MRD-2018 protocol and undergone simultaneous cytometric and cytomorphological BM investigation at the end of induction. A myelogram count was performed on 500 nucleated cells per BM smear. MRD was measured by 10-color flow cytometry with the 0.1 % cut-off for reliable MRD-positivity. The threshold of 5 % blasts was used as the criterion of complete remission (CR). Overall concordance of the two methods was 83.3 % for the CR status confirmation: in 335 out of 402 patients, the presence or absence of CR was stated using both techniques. Half of the 67 discordant samples were obtained from patients with a significant monocytic component of the leukemic population: 14 (20.9 %) with AML M4 and 20 (29.9 %) with AML M5. Among all FAB subtypes, the highest concordance rate was noted in patients with M1 variant (91.7 %), while the worst comparability – in children with megakarioblastic leukemia (M7 type, 72.7 %). Failure to achieve CR by cytomorphology did not influence the outcome of the patients who achieved CR as confirmed by immunophenotyping. At the same time, for flow cytometric BM investigation, achieving MRD negativity (< 0.1%) was the most significant favorable outcome predictor even at this rather early stage. Moreover, relapse incidence in children who were in CR but MRD positive (≥ 0.1 %) was higher than in patients who did not achieve CR at the end of induction according to flow cytometry (MRD ≥ 5 %), especially in the intermediate-risk group. This difference can be explained by more intensive chemotherapy (FLAI instead of HAM cycle) given to patients who did not achieve CR at the end of induction, and patients in the intermediate-risk group were additionally re-stratified to a high-risk group with subsequent hematopoietic stem cell transplantation. Flow cytometric and cytomorphological BM examination for the CR status confirmation at the end of induction in children with AML demonstrated a relatively high concordance rate (83.3 %). CR achievement by cytomorphology does not influence final outcome, although for the flow cytometry conventional threshold of 5 % also seems inadequate. We can assume that the modification of therapy is also required for patients with MRD ≥ 0,1 % at this stage of treatment.

   Platelet activation, shape change and aggregation are active processes that can be significantly dependent on the ambient temperature. However, there are conflicting data in the literature regarding the effect of temperature on platelets. In our work, we used a laser diffraction method to investigate the influence of temperature on the reaction of human platelets activated by
various agonists: ADP, U46619 (thromboxane mimetic), and thrombin (TRAP-6), that act through G-protein coupled receptors, and collagen, that activates the immunoglobulin receptor GPVI. For agonists that activate G-protein coupled receptors, we showed that an increase in temperature causes an acceleration of the initial platelet activation (shape change) and has no
significant effect on agonist sensitivity (EC₅₀). At the same time, hypothermia at low doses of such agonists potentiates platelet aggregation, which differs significantly from the effect of collagen. With increasing temperature, collagen accelerates platelet aggregation over the entire range of temperatures investigated. In this paper, we showed that the effect of temperature on platelet activation processes depends on both the dose of agonists and the type of activated receptors. In our study, we included healthy volunteers after obtaining a written informed consent. Blood samples were taken in accordance with the guidelines of the I. M. Sechenov Institute of Evolutionary Physiology and Biochemistry of the Russian Academy of Sciences and the Declaration of Helsinki. Studies with human erythrocytes were approved by the Ethics Committee of the I. M. Sechenov Institute of Evolutionary Physiology and Biochemistry of the Russian Academy of Sciences (Protocol No.3–03 dated 2 March 2021 and Protocol No.1–04 dated 7 April 2022).

   Monoclonal antibodies (mAbs) directed against GD2 are used as part of post-consolidation treatment for high-risk neuroblastoma (NB) patients with minimal residual tumor after induction therapy. It has been reported that a good end-of-induction response is associated with better event-free survival and overall survival rates. The use of mAbs in combination with chemotherapy has been shown to be effective in treating patients with relapsed NB in several international studies. Thus, the need to achieve a good end-of-induction response in high-risk NB and the feasibility of combining chemotherapy with mAbs serve as a rationale for employing immunotherapy during induction treatment of newly diagnosed patients with NB. Here, we present the results of the first Russian single-center study on the use of chemoimmunotherapy (CIT) during induction treatment in newly diagnosed patients with high-risk NB. In this prospective study carried out at the Dmitry Rogachev National Medical Research Center of Pediatric Hematology, Oncology and Immunology between January and August 2023, we enrolled 5 high-risk stage 4 NB patients aged > 18 months. This study was approved by the Institutional Review Board and the Independent Ethics Committee of the Dmitry Rogachev National Medical Research Center of Pediatric Hematology, Oncology and Immunology of the Ministry of Healthcare of the Russian Federation (Protocol No. 10э/9-22 dated 10. 12. 2022). Therapy was carried out according to the modified GPOH NB2004 protocol. Starting from the 3^rd course of induction, patients received 4 alternating courses of chemotherapy in combination with anti-G mAbs ch14.18/CHO (dinutuximab beta) at a dose of 10 mg/m²/day administered as a continuous infusion over 5 days. Toxicity was assessed as per the CTCAE 5.0 (Common Terminology Criteria for Adverse Events, version 5.0). A total of 20 courses of CIT were given. All patients completed induction therapy, with 3/5 (60%) achieving at least a partial response. There were no cases of unexpected severe toxicity or death. There were no pauses in the administration of mAb throughout all the CIT cycles, and all the patients received dinutuximab beta at full dose. Grade 3/4 toxicity was predominantly hematological. Non-hematological toxicity of grade ≥ III/IV included hypokalemia in 5/20 (25 %) courses, hypertension in 4/20 (20 %) courses and diarrhea in 3/20 (15 %) courses (due to viral infection). The need for opioid analgesics decreased with each successive course of treatment. The selected CIT regimen combining induction chemotherapy as per the GPOH NB2004 protocol and dinutuximab beta demonstrated safety and acceptable toxicity in newly diagnosed patients with high-risk stage 4 NB older than 18 months. Further multicenter cooperative studies will allow for the development of the optimal induction regimen consisting of chemotherapy and mAbs for improved survival in patients with high-risk NB.

   Gaucher disease (GD) is an autosomal recessively inherited disease that belongs to the group of lysosomal storage diseases. In GD, there is chronic activation of the macrophage system, disruption of the regulatory functions of macrophages, a shift in cytokine regulation towards pro-inflammatory cytokines and the development of chronic inflammation involving all immune cells, which can lead to changes in the composition of both major and minor populations of lymphocytes. Reduced beta-glucocerebrosidase activity impairs normal lysosomal function and autophagy, leading to the intracellular accumulation of glycosphingolipids, creating a self-sustaining cycle of impaired glucocerebroside utilization with the aggravation of both lysosomal and mitochondrial functions. It is known that untreated patients with GD are susceptible to more frequent and complicated infectious diseases, which presumably may arise due to changes in the functional activity of neutrophils caused by the disruption of the process of phagocytosis and oxidative burst in this cell population.

   The aim: to study the age-related features of the composition of the major and minor populations of peripheral blood lymphocytes, the activity of intracellular dehydrogenases of lymphocytes and the functional activity of neutrophils in children with GD.

   The study was approved by the Independent Ethics Committee and the Scientific Council of the National Medical Research Center for Children's Health of Ministry of Healthcare of the Russian Federation. The study included 73 children with GD, of which 26 children were examined at different age periods (1 child – 4 tests, 3 children – 3 tests, 22 children – 2 tests), the comparison group consisted of 148 healthy children comparable in age. The determination of the subpopulation composition of lymphocytes, the study of succinate dehydrogenase activity in the major and minor populations of lymphocytes (by immunocytochemical method) and the assessment of the functional activity of neutrophils were carried out using flow cytometry. The parameters of lymphocyte subpopulations were analyzed as percentage deviations from the age norm. The activity of intracellular dehydrogenases (succinate dehydrogenase, NADH dehydrogenase, lactate dehydrogenase) was determined by a cytomorphodensitometric method using image analysis. The statistical calculations were performed using the Statistica 10.0 program (StatSoft, USA). A decrease in NK cells and an increase in Th17 cells and activated T helper cells are usually observed in children with GD with age. The analysis of the activity of intracellular dehydrogenases revealed a decrease in the processes of oxidative phosphorylation and glycolysis in peripheral blood lymphocytes in children with GD. The functional activity of neutrophils in the majority of children with GD corresponded to the reference values.

   Acute lymphoblastic leukemia (ALL) is the most common cancer in the clinical practice of pediatric oncology/hematology. At the onset of the disease, patients can develop such a life-threatening complication as hyperleukocytosis with leukostasis that can manifest in many different ways, including ischemic priapism, an extremely rare type of leukostasis in children with ALL. Apart from death associated with hyperleukocytosis caused by the underlying disease, inadequate and poorly timed specific therapy and supportive care can lead to erectile dysfunction, impotence or intermittent priapism in the future. In this article, we report an extremely rare clinical case of ischemic priapism in a 12-year-old patient that developed at the onset of ALL and was the only manifestation of the disease as well as the reason for admission to hospital. The patient's parents gave consent to the use of their child's data, including photographs, for research purposes and in publications. Here, we analyzed special aspects of this complication, described modern treatment strategies and provided an international literature review. We emphasize the importance of urgent care delivery due to the critical prognostic significance of timely and adequate treatment provided by a multidisciplinary team.

   An uncommon genetic condition known as Fanconi anemia (FA) is characterized by bone marrow failure, chromosomal instability, and a high susceptibility to cancer. We report a case study of a patient diagnosed with FA who subsequently developed myelodysplastic syndrome (MDS). Informed consent was obtained from the patient’s parents/legal guardians. Consent for publication was obtained from the patient’s parents/legal guardians. We present a case of a 10-year-old boy with a known diagnosis of FA who experienced a decline in platelet count and subsequent bone marrow abnormalities suggestive of MDS. Cytogenetic analysis confirmed the diagnosis of FA with multiple chromosomal breaks, and flow cytometric analysis supported the diagnosis of MDS with excess blasts. The patient underwent a stem cell transplantation from a full matched donor (his father). Stem cell transplantation from a fully matched related donor can be effective in treating FA and associated complications. The transplantation was complicated by graft-versus-host disease and cytomegalovirus infection, however the child achieved complete normalization and exhibited no signs of diarrhea or dependence on immunosuppressive drugs at the six-month follow-up. The case report emphasizes the significance of multidisciplinary care and close follow-up for pediatric FA and MDS patients, suggesting further research and standardization of diagnostic procedures.

   Ten-year progression-free survival in children, adolescents and young adults with relapsed/refractory Hodgkin lymphoma (r/r HL) does not exceed 50 %. Brentuximab vedotin (BV) and immune checkpoint inhibitors (ICIs), such as nivolumab and pembrolizumab, are successfully used for the treatment of adults with r/r HL. In this study, we analyzed our experience of ICI treatment of children and adolescents with r/r HL. This study was retrospective and included patients with r/r HL under 18 years of age, who received ICI therapy. Twenty patients were included. All of them had been treated with BV, 35 % (n = 7) of patients had undergone auto-HSCT before treatment with ICIs. Among all patients, 45% (n = 9) received ICIs for the first refractory relapse, 40 % (n = 8) due to refractory disease progression and 15 % (n = 3) received therapy for the second relapse. Two patients received ICIs in combination with other drugs, the response to therapy in 2 patients was unknown. Nine (56 %) of 16 patients achieved a metabolic response, one patient had no evidence of vital tumor cells based on the results of a biopsy of a lesion positive on positron emission tomography, thus a response was achieved in 10 (63%) patients. The survival rate analysis included 20 patients. Median follow-up from ICIs initiation was 1.2 years (interquartile range: 0.7–1.5 years). The probability of 1-year overall survival (OS) rate reaches 69 % (95 % confidence interval (CI) 46.4–91.6), 2-year OS – 60.4 % (95 % CI 35.1–85.7), 3-year OS – 40.3 % (95 % CI 4–76.6). In this study, we demonstrated the effectiveness of the treatment with ICIs as an element of therapy in children and adolescents with r/r HL, who had not responded to previous lines of therapy, including BV. The patients' parents gave consent to the use of their children's data, including photographs, for research purposes and in publications.

   The development of modern technologies and an increase in the incidence of severe pediatric acute respiratory distress syndrome in children with oncohematological diseases provide some evidence for the medical society to reconsider the indications for extracorporeal membrane oxygenation in this group of patients. The literature review presents an analysis of recent studies on extracorporeal membrane oxygenation usage in children with oncohematological diseases and after hematopoietic stem cell transplantation. The reviewed studies revealed an improvement of the survival rate among such patients over the last decade.

   ALK-positive anaplastic large cell lymphoma is a mature T-cell lymphoma characterized by translocations that involve the ALK receptor tyrosine kinase coding gene. This illness is known to almost exclusively affect children and young adults. The biology of ALK-positive anaplastic large cell lymphoma is fairly well researched today, with recent studies focusing on the histogenesis of this neoplasm. In this review, we analyze the existing world literature data on the etiology and pathogenesis of this disease.

   The evolution of hemophilia treatment is rapidly developing. Both new factor replacement and non-factor therapy have appeared in recent years. One of the most important problems of factor replacement therapy is the relatively short half-life of coagulation factor VIII (FVIII), with an average of about 8–12 hours in adults, ranging in individual patients between 6 and 24 hours, and even shorter in younger children. This forces patients, especially children, to administer the drug quite often (3–4 times a week), reducing the quality of life and adherence to treatment. The appearance of recombinant FVIII products with an increased half-life allows to reduce the number of infusions per week, improving the quality of life of patients without compromising the safety and efficacy of treatment. However, the structure of these products leads to the changes in the results of laboratory tests of FVIII activity carried out to monitor the efficacy of treatment. In this article, we will consider the current methods of laboratory control of products with an increased half-life of FVIII currently available in Russia. We want to assess the discrepancy between the one-stage clotting method and chromogenic method for each FVIII product, as well as the laboratory's capabilities in monitoring non-factor and combined therapy for hemophilia A.

   Acute leukemias of ambiguous lineage (ALAL) are rare acute leukemias (AL) that exhibit specific features of more than one hematopoietic lineage or show no distinct evidence of lineage differentiation. Immunophenotyping plays a key role in the diagnosis and classification of ALAL. Despite the availability of diagnostic criteria for ALAL proposed by different expert groups, the accurate diagnosis of ALAL representing a rare and heterogeneous group of diseases remains a challenge. In this paper, we present a brief analysis of 97 pediatric ALAL cases. Such a large cohort of cases with ALAL (ALALs comprising less than 1 % of all pediatric AL) was obtained as a result of the centralized diagnosis of AL. With regard to the obtained results, we have developed the guidelines for the interpretation of the results of immunophenotyping in the diagnosis of ALAL and for the integration of findings from flow cytometry, cytomorphology and genetic testing for the accurate diagnosis and classification of this group of AL.

19 марта 2024 г. в онлайн-режиме состоялось совещание экспертов по вопросу критериев перевода пациентов детского возраста с гемофилией B на препарат албутрепенонаког альфа.