Vol 22, No 1 (2023)

This article discusses the potential of droplet digital polymerase chain reaction (PCR) for the diagnostic detection and monitoring of the allelic load of the BRAF V600E mutation in circulating cell-free DNA and myeloid progenitor cell population in the bone marrow of patients with Langerhans cell histiocytosis (LCH). Droplet digital PCR may serve as a useful tool for the monitoring of minimal residual disease and improve our understanding of the pathogenesis of Langerhans cells histiocytosis. 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.

Anaplastic large cell lymphoma (ALCL) expressing the anaplastic lymphoma kinase (ALK) (ALK⁺ ALCL) is a rare type of lymphoma which comprises 10-15% of all non-Hodgkin lymphomas in children and 2–3% in young adults. Relapsed/refractory disease occurs even more rarely (25–40% of all cases). There is as yet no standard treatment for relapsed/refractory ALK⁺ ALCL. Patients with ALK⁺ ALCL usually present at advanced stages of the disease with extranodal involvement (skin, soft tissues, bones, lungs, liver, spleen and bone marrow) and B symptoms. ALK-positive ALCL affects males more often than females. There are two morphological variants: the common type (65% of cases) and the non-common type which is associated with a poorer prognosis. ALK⁺ ALCLs are often associated with t(2;5) and t(1;2), resulting in the formation of the NPM-ALK and the TPM3-ALK fusion proteins, respectively. Data about the treatment of relapsed/refractory ALK⁺ ALCL are limited. Earlier, targeted therapies (brentuximab vedotin (BV), ALK inhibitors) and risk-adapted chemotherapy followed by hematopoietic stem cell transplantation (HSCT) for remission consolidation were shown to be highly effective. A total of 15 patients with relapsed/refractory ALK⁺ ALCL were treated at the R.M. Gorbacheva Research Institute starting from 2002. Fourteen (93%) patients had ALK-positive ALCL of common morphology and one (7%) patient had the non-common variant (histiocytic). The study was approved by the Independent Ethics Committee and the Scientific Council of the Pavlov University. The expression of CD3 on tumor cells was assessed (CD3 positive: n = 4 (27%), CD3 negative: n = 8 (53%), no data: n = 3 (20%). The median age at the diagnosis was 26 years (11 months– 37 years). The median follow-up from the diagnosis was 9 years (1–19 years). Nine (60%) patients were aged > 18 years and six (40%) patients were aged < 18 years. There were 10 (67%) males and 5 (33%) females. At onset, 2 (13%) patients were diagnosed with early-stage disease (stage II), while the others were diagnosed with advanced-stage disease: 2 (13%) patients had stage III disease and 11 (74%) had stage IV disease. Staging was performed according to the St. Jude staging system (in children) and the Ann Arbour staging classification (in adults). Thirteen (86%) patients had extranodal involvement. Four (27%) patients had refractory disease (progression within the first three months or the absence of complete remission after the first-line treatment) and the rest 11 (73%) patients had recurrent ALK-positive ALCL. Six patients developed early relapse (< 12 months after remission was achieved); 5 patients had late relapse (after > 12 months of remission); local (1 site) and systemic relapses were diagnosed in 7 and 4 patients, respectively. Our patients received from 2 to 7 lines of treatment (the median is 4). In the first line of therapy, the patients were treated according to NHL-BFM based regimens (n = 9; 60%), the CHOP (n = 5; 33%), and the HyperCVAD (n = 1; 7%) protocols. In the second line of therapy, 8 (53%) patients were treated according to NHL-BFM based regimens; 2 (13%) patients were treated with GDP; 1 (7%) patient received DHAP chemotherapy; 1 (7%) patient received a combination of methotrexate and vinblastine (MTX + V); 1 (7%) patient received bendamustine as a single agent. Two (13%) patients were treated with chemotherapy in combination with targeted drugs (GDP + BV, n = 1; NHL-BFM + crizotinib, n = 1). As a third or subsequent line of treatment, the patients received a variety of chemotherapy regimens (n = 5; 33%) and chemotherapy in combination with targeted drugs (n = 10; 67%). Five (33%) patients underwent ALK-inhibitor therapy (crizotinib (n = 4) and ceritinib (n = 1)). Seven (46%) patients were treated with BV (BV as a single agent (n = 4) and BV + chemotherapy (n = 3)). The median number of treatment lines before autologous HSCT (auto-HSCT) and allogeneic HSCT (allo-HSCT) was 2 (2–3) and 3 (3–4), respectively. Auto-HSCT was carried out in 11 (73%) cases. Nine (60%) patients underwent allo-HSCT (from a matched unrelated donor (n = 6), from a matched related donor (n = 2), and from a haploidentical donor (n = 1)). One patient received NK cells from a haploidentical donor as maintenance. In 5 (33%) cases, alloHSCT was carried out following auto-HSCT. The conditioning regimens (CR) used for auto-HSCT included BEAM (carmustine – 300 mg/m², etoposide – 800 mg/m², Cytosar – 1600 mg/m², melphalan – 140 mg/m²) – in 5 (45%) patients; BeEAM (bendamustine – 320 mg/m², etoposide – 800 mg/m², Cytosar – 1600 mg/m², melphalan – 140 mg/m²) – in 5 (45%) patients; and BuCy (Cyclophosphan – 100 mg/kg, busulfan – 14 mg/kg) – in 1 (10%) case. Seven (78%) patients undergoing allo-HSCT received the FluBenda conditioning regimen (fludarabine – 90–150 mg/m², bendamustine – 390 mg/m²) and post-transplant Cyclophosphan and calcineurin inhibitors for the prevention of graft-versus-host disease (GVHD) (n = 7; 78%); one (11%) patient received the FluMel regimen (fludarabine – 150 mg/m², melphalan – 140 mg/m²) and CsA/MTX (Cyclosporin А, methotrexate) for GVHD prevention; and in 1 case (11%) data on the RC and GVHD prophylaxis were missing. Overall response to the second line of treatment was achieved in 10 (67%) patients, with complete response observed in 7 (47%) cases, and partial response –
in 3 (20%) cases. Five out of the 7 patients treated with BV during different lines of therapy managed to achieve complete response. Four out of the 5 patients who had undergone treatment with ALK inhibitors, demonstrated complete response. The 10-year overall survival (OS) rate of the study patients reached 90% (95% confidence interval (CI) 47–99). The 10-year progression-free survival (PFS) rate after the second line of treatment was 39% (95% CI 13–64). The 10-year OS and PFS rates after auto-HSCT were 100% and 35% (95% CI 8–64) respectively. The 5-year OS following allo-HSCT was 85% (95% CI 33–98), while PFS was 60% (95% CI 19–85). Four out of the 11 patients who had undergone auto-HSCT relapsed, and 2 patients progressed. Median time to relapse/progression was 8 (6–27) months. Three out of the 9 patients who had been treated with allo-HSCT ended up relapsing (median time: 8 (6–17) months). Two patients achieved repeated remission (in one case, it was the result of treatment with ceritinib, while in the other case it became possible after the resection of the lesion, radiotherapy and prescription of crizotinib), and 1 study patient died as a result of disease progression 17 months after allo-HSCT. The 6 patients who had achieved complete remission before undergoing allo-HSCT, are still in CR. Five out of the 9 patients developed grade I–II acute GVHD with skin involvement but did not show any signs of chronic GVHD. The observed complications of chemotherapy and auto-HSCT were standard and manageable and were not the focus of attention in this study. Taking into account the high probability of developing resistance to ALK inhibitors and the high risk of relapse after treatment with BV, targeted therapy should be used to prepare patients for HSCT. The use of ALK inhibitors and BV in our study led to repeated remission in 80% and 71% patients respectively. It was demonstrated that in the majority of cases even heavily pretreated patients with ALK⁺ ALCL can be cured (which is not the case with other non-Hodgkin lymphomas), especially if allogenic HSCT (allo-HSCT) is carried out. Still, we think that auto-HSCT can also be considered for remission consolidation since OS rates following auto-HSCT and allo-HSCT are comparable (100% and 85%). Moreover, auto-HSCT can also be a valid option in the absence of a fully matched donor, i.e. when only an alternative (haploidentical or partially matched) donor is available, since the use of haploidentical HSCT in ALCL patients has not been studied well enough yet. Further research on the matter is warranted. It was demonstrated that a non-myeloablative conditioning regimen before allo-HSCT (FluBenda) could be opted for in patients with relapsed/refractory ALK⁺ ALCL and that it was similarly effective as myeloablative RC when compared with a historical control group. Disease status before HSCT was proven to have a statistically significant influence on PFS (the best prognosis was associated with complete remission). At the same time, other factors did not impact the prognosis. This may be explained by the relatively small number of patients included in the study. Relapsed/refractory ALK⁺ ALCL is a disease with a relatively good prognosis even in heavily pretreated patients. Targeted therapy is a very important and effective step in preparation for HSCT. Allo-HSCT is more effective than auto-HSCT but the latter can also be considered a valid therapeutic option.

Acute lymphoblastic leukemia (ALL) is the most common pediatric malignancy. Philadelphia (Ph)-like B-cell acute lymphoblastic leukemia (B-ALL) is defined by a gene expression profile similar to Phpositive B-ALL and shows a large number of genetic alterations in the cytokine receptor and kinasesignaling pathway genes that contribute to its aggressive phenotype and frequent disease recurrence – the main cause of death in affected children. Here, we aimed to correlate CRLF2 expression and JAK2 mutations in B-ALL patients with other prognostic factors and the patients’ outcomes as well as to evaluate their prognostic significance. The study was approved by the local institutional review board and written consents were obtained from a parent of each child before their enrolment. We included 54 newly diagnosed B-ALL pediatric patients (median age: 9.0 (2.0–18.0)) who were stratified either into a standard-risk (SR) or high-risk (HR) group and treated according to the modified BerlinFrankfurt-Münster 90 protocol (ALL-BFM 90). Fresh bone marrow samples were used to determine CRLF2 expression as well as to search for the JAK2 V617F mutation. Normal CRLF2 expression was reported in the SR patients much more often than in the HR group, while its overexpression was more common in the HR patients than in the SR ones (22 vs 6 and 18 vs 8, respectively, p < 0.001). CRLF2 was also more often overexpressed in the MRD-positive cases than in the negative ones (17 vs 9, p < 0.001), while normal CRLF2 expression was more common in the MRD-negative patients compared to the MRD-positive ones (24 vs 4, p < 0.001) which supports the unfavorable prognostic value of CRLF2 in relation to MRD positivity at the end of the induction treatment. JAK2 mutation was detected only in 2 patients belonging to the CRLF2 overexpression group which made the assessment of the prognostic significance of this mutation impossible. Notably, none of the patients with normal CRLF2 expression ended up relapsing while 4 patients with overexpressed CRLF2 developed a relapse (p = 0.031). The study subjects were followed up for up to 24 months, and we did not find CRLF2 overexpression to negatively influence overall survival, however, it did have an adverse effect on relapse-free survival. In summary, CRLF2 overexpression was found to be an unfavorable prognostic factor in childhood ALL as it was expressed more in high-risk patients and in those with poor treatment response. The analysis of CRLF2 expression in B-ALL pediatric patients may help in risk stratification and can potentially offer new treatment options based on novel CRLF2 inhibitors.

Nijmegen breakage syndrome (NBS) and ataxia-telangiectasia (AT; Louis–Bar syndrome) are primary immunodeficiencies (PID) associated with chromosome instability and DNA repair defects that predispose individuals to an increased risk of various malignancies. In our study, we retrospectively analyzed clinical characteristics and outcomes of 28 cancer cases in 14 patients with AT and 10 patients with NBS who had been treated at the Dmitry Rogachev National Medical Research Center of Pediatric Hematology, Oncology and Immunology between January 2007 and December 2022. 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 most common type of malignancy was mature B-cell non-Hodgkin lymphoma (B-NHL) (42%), with diffuse large B-cell lymphoma (DLBCL) accounting for 91% of all B-NHL cases. Other cases included T-cell acute lymphoblastic leukemia (ALL) (n = 3), B-cell ALL (n = 2), Hodgkin lymphoma (n = 3), NK/T-cell lymphoma (n = 1), T-cell lymphoblastic lymphoma (n = 1), peripheral T- cell lymphoma (n = 2), medulloblastoma (n = 1) epithelioid rhabdomyosarcoma (n = 1), T-cell prolymphocytic leukemia (n = 2). A total of 4 patients were diagnosed with second malignancies (2 children with AT and 2 children with NBS. The diagnosis of PID was suspected or confirmed before the initiation of cancer therapy in 62% of AT patients and in 100% of NBS patients. Treatment was given in accordance with standard protocols with chemotherapy dose modifications. A total of 93% of patients with AT and 80% of patients with NBS required dose reduction. The level of response was quite high: 81% of patients with AT and 58% of patients with NBS achieved complete remission. According to our data, the use of reduced-dose chemotherapy regimens helps to achieve an acceptable toxicity profile without reducing the overall effectiveness of treatment.

Aplastic anemia is a life-threatening condition characterized by the suppression of all hematopoietic lineages in the bone marrow. Empty intertrabecular spaces are replaced by adipose tissue. With modern MR techniques for assessing fat fraction, it has become possible to capture these changes. The fat fraction is estimated as the ratio of the signal intensity from fat to the sum of the fat and water signals. Aim of the study: to assess the diagnostic value of bone marrow fat fraction quantification in patients aged < 18 years with aplastic anemia. 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 of the Ministry of Healthcare of the Russian Federation. The study included 66 participants aged under 18 years. A control group consisted of 33 healthy subjects with a mean age of 13.03 ± 2.83 years. A group of interest included 33 children with a confirmed diagnosis of aplastic anemia, with a mean age of 12.31 ± 4.39 years. The study was carried out at the Dmitry Rogachev National Medical Research Center of Pediatric Hematology, Oncology and Immunology of the Ministry of Healthcare of the Russian Federation; all scanning was performed on a Philips Achieva 3.0T MRI scanner using the mDixon-quant sequence in the iliac bones and lumbar vertebrae. Our results showed that bone marrow fat fraction was significantly higher in the aplastic anemia group than in the controls. In the patients with aplastic anemia, the mean fat fraction values in the iliac bones and in the L4, L5 vertebrae were 82.62 ± 10.92% and 73.52 ± 17.52%, respectively. In the control group, the mean fat fraction values for these sites were 51.04 ± 11.41% and 31.43 ± 10.61%, respectively. We found a significant difference in fat fraction values for the same sites between the groups (p < 0.01). Bone marrow fat fraction quantification by MRI allows for the detection of decreased cellularity of the marrow in patients under 18 years of age with aplastic anemia compared to healthy children.

Juvenile idiopathic arthritis (JIA) is one of the most common chronic inflammatory diseases occurring in childhood, associated with decreased bone mineral density (BMD) and increased risk of osteopenia and osteoporosis, which increases the fracture risk. Aim of the work: to assess BMD and bone turnover markers (serum osteocalcin for bone formation and C terminal telopeptide of type 1 collagen for bone resorption) in JIA patients and their relation to disease activity. This study included 50 patients with JIA (female:male – 20:30). The study was approved by the Ethical Research Committee and Institutional Review Board of the Faculty of Medicine, Menoufia University, Egypt (Approval number: 19519INTPH48). Written informed consent was obtained from each patient or the parents. These patients were diagnosed with JIA according to the criteria of classification of the International League of Associations for Rheumatology. BMD was measured by Dual-energy X-ray absorptiometry (DEXA) of the lumbar spine using the Z-score. The results were correlated with JIA disease duration, disease activity, bone turnover markers and serum level of vitamin D. Clinical disease activity was evaluated by juvenile arthritis disease activity score (JADAS-27). There was a significant negative correlation between DEXA Z-score and disease activity (p-value < 0.001), bone turnover markers (p-value < 0.001), and duration of JIA (p-value < 0.05). There was a significant difference between vitamin D level and DEXA Z-score; DEXA Z-score was lower in vitamin D deficient patients. JIA patients with higher disease activity are at a higher risk of osteopenia and osteoporosis. Well-timed and efficient treatment of JIA and proper control of disease activity may help to improve the bone status and reduce the incidence of osteoporosis. Consequently, valuable targeted interventions are essential to preserve bone health during JIA.

Rosai–Dorfman disease (RDD) is a rare histiocytic disorder, which occurs at any age, can affect almost any organs and tissues, does not have pathognomonic symptoms and could be confirmed only by histological examination of the affected tissue. The article describes the successful treatment of a child with RDD with lymph nodes, nasopharynx, subcutaneous tissue, spleen and bones involvement, by multistep surgical treatment and chemotherapy. A review of the literature is provided, including recommendations for the examination and treatment of patients with RDD. The patient's parents agreed to use the information, including the child's photo, in scientific research and publications.

Here we report a clinical case of a patient with BRAF-positive Langerhans cell histiocytosis treated with combination therapy including trametinib. As the patient was undergoing long-term therapy with a BRAF inhibitor, his underlying disease reactivated. Hence it was suggested that the child might have become resistant to the treatment as a result of a subclonal mutation. It was concluded that this event undermined the efficacy of long-term therapy with BRAF inhibitors and highlighted the need for further study of possible molecular genetic mechanisms involved in the pathogenesis of Langerhans cell histiocytosis, as well as the need for the development of new treatment approaches. The patient's parents gave consent to the use of their child's data, including photographs, for research purposes and in publications.

X-linked agammaglobulinemia (XLA), or Bruton’s agammaglobulinemia, – is a primary immunodeficiency, caused by defects in the BTK gene encoding Bruton’s tyrosine kinase. The BTK defects lead to the arrest of B-lymphocyte development and, as a result, agammaglobulinemia. The disease manifests with recurrent infections starting in infancy. The gold standard of XLA treatment – intravenous or subcutaneous immunoglobulin substitution – proved effective in various multicenter studies and increases the quality of life of XLA patients. However, there are cases of delayed disease verification, and untimely delayed treatment, which leads to severe, recurrent infections and life-threatening conditions. We present a review of the literature and case report of an XLA patient with ecthyma gangrenosum. The patient's parents gave consent to the use of their child's data, including photographs, for research purposes and in publications.

Evans syndrome, a combination of autoimmune hemolytic anemia and immune thrombocytopenia, is a rare disease in children. In childhood, it may turn out to be one of the first manifestations of a primary immunodeficiency or an immune dysregulation syndrome. Here we present a clinical case of a patient who was initially diagnosed with Evans syndrome and did not respond well to therapy. Based on the results of genetic testing, the child was then diagnosed with primary immunodeficiency, namely, activated PI(3)kd syndrome. During follow-up, the patient developed lymphoma and had to undergo radical treatment (allogeneic hematopoietic stem cell transplantation). The patient's parents gave consent to the use of their child's data, including photographs, for research purposes and in publications.

Flow cytometry is one of the key technologies for acute leukemia (AL) diagnostics. Nevertheless, lack of technological standards hampers implementation of immunophenotyping data in treatment protocols. Earlier our group published the acute lymphoblastic leukemia diagnostic standards. In this paper, we present the updated guidelines for initial immunophenotyping of ALs. This wellharmonized approach includes recommendations for monoclonal antibodies choice, sample preparation, cytometer setup, data analysis and interpretation as well as for the report writing. These guidelines allows application of diagnostic flow cytometric studies in all types of AL.