Vol 21, No 2 (2022)

The majority of patients with Hodgkin lymphoma (HL) are cured, which represents one of the best cure rates in oncology. However, the prognosis is not as favorable in case of relapsed or refractory (RR) disease. Autologous hematopoietic stem cell transplantation (auto-HSCT) is an effective way to consolidate remission in patients with RR HL. Despite the many years of experience and the availability of results of randomized trials confirming the efficacy of high-dose chemotherapy in adults, the role of auto-HSCT in children with HL has not been studied as extensively, and there are only a limited number of publications on the subject. As is the case with the majority of other pediatric tumors, RR HL is a rare entity, which is why it is so difficult to study it. Here we share the experience of the R. M. Gorbacheva Research Institute for Pediatric Oncology, Hematology and Transplantation in auto-HSCT in children and adolescents with HL. The study was approved by an Independent Ethics Committee and the Scientific Council of the I.P. Pavlov First Saint-Petersburg State Medical University. We included 54 patients with RR HL who had undergone auto-HSCT during the period from 2007 to 2021. Refractory disease (n = 29; 54 %) was diagnosed in case of HL progression either during first-line therapy or in the first 3 months after the completion of the treatment. Relapsed disease was diagnosed in 25 (46 %) children. Early HL relapse (< 12 months since the start of therapy) was evident in 18 (72 %) patients, while late HL relapse (≥ 12 months since the start of therapy) occurred in 7 (28 %) children. The median number of lines of therapy before auto-HSCT was 3 (1–6). The first line of treatment was chemotherapy in accordance with the GPOH-HD (n = 27; 50 %), BEACOPP (n = 19; 35 %), or other protocols (n = 8; 15 %); the second line involved the use of IEP/ABVD (n = 14; 27 %), DHAP (n = 12; 23%), ICE (n = 13; 25 %), or other combinations (n = 13; 25%); and third-line treatment consisted of DHAP (n = 9; 29 %), a combination of brentuximab vedotin and bendamustine (n = 8; 26%), immune checkpoint inhibitors (ICIs) (n = 7; 22.5 %) or other regimens (n = 7; 22.5 %). ICIs were used for remission induction prior to auto-HSCT in 14 (26 %) patients. Response was assessed using the Lugano classification. Status before transplantation: complete remission (CR) – 21 (39 %) patients, partial remission (PR) – 30 (56 %), disease stabilization – 2 (3.5 %), disease progression – 1 (1.5 %). The BEAM conditioning regimen was used in 17 (31 %) patients, and the BeEAM regimen – in 32 (59 %) patients. The 3-, 5- and 10-year overall survival (OS) was 88% (95 % confidence interval (CI) 74–95), 80% (95 % CI 62–90) and 63% (95 % CI 34–81) respectively. The 10-year progression-free survival (PFS) was 46% (95 % CI 24–65). The median follow-up was 3.3 (0.1–12.3) years. The long-term PFS in children with CR and PR was 72% (95 % CI 41–89) and 33 % (95 % CI 8–61) respectively (p = 0.067). A total of 9 (16.7 %) patients died during follow-up. The main cause of death was progressive HL (n = 6), while some patients died in the early post-transplant period due to infections (n = 3; 5.6 %). The median time to relapse or progression after auto-HSCT was 6 (1–77) months. Out of 17 (31 %) patients with relapsed or progressive HL after auto-HSCT, 9 (53 %) children are alive at a median follow-up of 2.3 (0.7–9) years. Considering that our study included patients who had been more extensively pre-treated (the median number of lines of therapy – 3) than patients in the majority of other studies (the median number of lines of therapy – 2), it can be assumed that our results are superior to historical data. The improvement of transplantation outcomes observed over time can be attributed to better supportive treatment and probably, to the use of immunotherapy. According to the Center for International Blood and Marrow Transplant Research (CIBMTR), it is crucially important that long-term survival in children with RR HL be monitored closely since it can be drastically different from results obtained during the first years of follow-up - due to late relapses and complications of the received treatment. The 10-year survival rates show that the RR HL problem is yet to be resolved. With the help of auto-HSCT, approximately half of children and adolescents with RR HL can be cured. One of the most important favorable prognostic factors in these patients is the achievement of CR before transplantation. The use of immunotherapy for remission induction before auto-HSCT is also promising.

   Hematopoietic stem cell transplantation (HSCT) from an allogeneic donor is a standard treatment for high-risk leukemia that makes it possible to cure patients with chemotherapy-resistant leukemia. “Graft-versus-host” disease (GVHD) is the key biological and clinical problem associated with HSCT. Ex vivo depletion of ab-T cells has been used at the Dmitry Rogachev National Medical Research Center of Pediatric Hematology, Oncology and Immunology since 2012 as a means to prevent GVHD after HSCT. The successful application of this approach to GVHD prevention has reduced the risk of clinically significant acute GVHD and chronic GVHD to 15–20 %, and transplant-related mortality – to 5–10 %. The risk of relapse is 20–30 %, but when HSCT is performed in active disease, it increases to 50 %. The role of epigenetic mechanisms in the formation of the tumor phenotype has been established, and pharmacological approaches have been proposed. New drug classes include proteasome inhibitors such as bortezomib. The relatively low toxicity of epigenetic therapy and proteasome inhibitors makes their use in the post-transplant period an attractive approach to relapse prevention. We regarded prophylaxis after HSCT as one of the possible approaches that could help reduce relapse rate. Here we explore the effects of hypomethylation therapy (azacitidine) combined with an HDAC inhibitor (valproic acid) and a proteasome inhibitor (bortezomib). 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. Combination therapy cycles were carried out after engraftment and in some patients, were accompanied by infusions of modified donor lymphocytes enriched in NK cells or memory T cells. The experimental group included 35 pediatric patients with hemoblastoses who had received HSCT from March 2013 to November 2016. The median age was 6.9 years. Twenty-three children had acute myeloid leukemia (AML), 11 patients – acute lymphoblastic leukemia (ALL), and one patient was diagnosed with juvenile myelomonocytic leukemia (JMML). Twenty-one patients were in complete clinical and hematologic remission at the time of HSCT while 14 patients (AML – 12, ALL – 1, JMML – 1) underwent HSCT in active disease. The patients were conditioned with treosulfan and melphalan (n = 26), thiotepa (n = 8), or etoposide (n = 1). Post-transplantation chemotherapy included azacitidine at a dose of 30 mg/m 2 IV for 5 days, bortezomib at a dose of 1.3 mg/m 2 s.c. (No. 2), and valproic acid at a dose of 250 mg 3 times a day р.о. (No. 6). The patients were planned to receive 3 cycles of post-transplantation chemotherapy with a break of 30 days between each treatment. Donor lymphocyte infusions were given on Day 7 of each cycle. A total of 92 cycles were conducted after HSCT. The most common side effect of treatment was hematologic toxicity. Transient visceral toxicity was registered after 46 (50 %) chemotherapy cycles. There were no cases of acute GVHD after donor lymphocyte infusions. At the time of the analysis, the median follow-up was 6.5 years. The cumulative risk of grade II–IV acute GVHD was 19% (95 % confidence interval (CI) 12–32). Nineteen patients relapsed at a median of 6 months after HSCT. Sixteen patients died of disease progression or complications related to subsequent treatment at a median of 11.76 months. The cumulative probability of relapse was 54% (95% CI 40–73). The cumulative probability of relapse in the patients transplanted in clinical and hematologic remission and those in active disease was 48% (95% CI 30–75) and 64 % (95 % CI 43–95), respectively. The event-free survival in the entire group of patients was 46 % (95 % CI 29–62). The event-free survival rates in the patients transplanted in remission and in active disease were 52% (95% CI 31–73) and 36 % (95 % CI 10–60), respectively. There were no deaths of complications of HSCT that were not associated with the recurrence of the disease in the experimental group. The cumulative risk of relapse among the AML patients in clinical and hematologic remission at the time of HSCT and those with advanced stage of the disease was 45 % (95 % CI 40–74) and 58 % (95 % CI 36–94), respectively. The overall survival was 53 % (95 % CI 31–73); the overall survival for the patients transplanted in remission and those who received HSCT in active disease was 63% (95 % CI 35–92) and 41% (95% CI 14–70), respectively. The event-free survival was 54% (95% CI 30–62) in the remission group and 41% (95 % CI 14–69) in the relapse group. In the ALL patients, the cumulative risk of relapse was 54 % (95 % CI 31–93); the overall and event-free survival rates were 72 % (95 % CI 46–91) and 45 % (95 % CI 16–75), respectively. Our analysis of the overall experience of prophylactic treatment with decitabine and azacitidine after ab-T cell-depleted HSCT suggests that this approach should be considered purely experimental and acceptable for prospective clinical studies in clearly defined cohorts of patients.

   Hematopoietic stem cell transplantation (HSCT) is an effective method of therapy which is widely used for the treatment of a number of diseases in children. “Graft-versus-host” disease (GVHD) is a severe complication that can develop after HSCT. The incidence of GVHD, according to some authors, ranges from 40 to 60%. The main target organs of acute GVHD are skin, liver, and gastrointestinal tract. Early diagnosis is critical in choosing the optimal treatment. The clinical manifestations of intestinal GVHD are non-specific. Currently, the “gold standard” of GVHD diagnosis is the histopathological assessment of biopsy samples. However, a conditioning regimen, cytomegalovirus infection, and/or treatment with immunosuppressive drugs can also induce apoptosis and lead to the same microscopic changes as the ones seen in GVHD. The main goals of an endoscopic examination are the visual assessment of the mucosa and a biopsy. Several articles describe macroscopic changes in the colonic mucosa characteristic of GVHD which can be used as a diagnostic criterion. Here, we review related literature and report a case of severe acute GVHD as well as evaluate the patient’s clinical manifestations and endoscopic findings. The patient's parents gave consent to the use of their child's data, including photographs, for research purposes and in publications.

   THROMB-HEM is an observational research study discovering the prevalence, risk factors and features of the course and therapy of deep venous thrombosis (DVT) in children with hemoblastosis and bone marrow aplasia which was conducted on from 2012 to 2017 on the basis of the Dmitry Rogachev National Medical Research Center of Pediatric Hematology, Oncology and Immunology.

   Aim: assessment of the DVT prevalence in children with hemoblastosis and and bone marrow aplasia based on the results of the THROMB-HEM study. The cumulative incidence rate (CIR) of objectively confirmed DVT, symptomatic (sDVT) and asymptomatic (aDVT) DVT in was assessed in children hospitalized in the center from 01.01.2013 to 12.31.2017 in order to verify and treat various hemoblastosis and bone marrow aplasia. 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. Data from 1623 patients were included for CIR DVT analysis. Among the patients included in the event analysis, DVT was detected in 361 children (285 aDVT and 73 sDVT, in 3 cases there were no data on the clinical picture of DVT). The maximum patient observation time was 5 years. The median follow-up time for patients was 332.15 days (95 % confidence interval (CI) 295.65–379.60). At the third year of follow-up, CVR DVT was 34.8 % (95 % CI 31.3–38.7), CVR aDVT was 28.9 % (95 % CI 25.7–32.5), while sDVT was 8.2 % (95 % CI 5.8–11.5). Unlike aDVT, most sDVT occurred within the first 6 months of therapy. DVT, mostly aDVT, is a common finding in children receiving inpatient treatment for hemoblastosis and bone marrow aplasia, which dictates the need for further research to assess risk factors and the effectiveness of therapy and prevention of these complications.

   Retinoblastoma is an aggressive eye tumor originating from maturing cone precursors in the developing retina and most commonly seen in childhood. In 98 % of patients, retinoblastoma is caused by bi-allelic inactivation of the RB1 tumor suppressor gene. Approximately 40 % of disorders in the RB1 gene are germline.

   This study aimed to analyze the frequency of germline RB1 variants in a cohort of Belarusian patients with retinoblastoma and to correlate the variants with clinical phenotypes. The study was approved by an Independent Ethics Committee and the Scientific Council of the Belarusian Research Center for Pediatric Oncology, Hematology and Immunology. The study included 20 patients from unrelated families (9 patients with unilateral retinoblastoma, 11 – with bilateral). Two out of eleven patients with bilateral retinoblastoma had a positive family history. Genomic DNA was extracted from peripheral blood mononuclear cells. Using polymerase chain reaction, we obtained fragments including sequences of all exons, regions of splice sites and promoter regions of the RB1 gene. Nucleotide sequences of the obtained amplicons were detected by next-generation sequencing. All clinically significant variants were confirmed by Sanger sequencing. Multiplex ligation-dependent probe amplification (MLPA) or fluorescence in situ hybridization (FISH) were used to detect gross alterations. A genetic analysis of blood relatives was carried out for five probands with detected germline variants. We identified 13 different variants in 14 patients: 38.5 % (n = 5) of them were defects in splice sites; 15.4 % (n = 2) – missense mutations; 15.4 % (n = 2) – small deletions (frameshift); 23% (n = 3) – large deletions; 7.7% (n = 1) – nonsense mutations. Four of these variants had not been previously reported in patients with retinoblastoma from other populations (exon 3: c.350_351delTT, p. Phe117TyrfsTer2; exon 8: c.861+2T>G; exon 24: c.2520+4A>G; Del of exons 16, 17). Germline mutations were detected in 33.3 % (3/9) of patients with unilateral retinoblastoma and in 100% (11/11) of patients with bilateral disease. A genetic screening of relatives showed that three variants were de novo, and two variants were inherited from parents in families with a positive history of retinoblastoma. Here we reported the first results of genetic examination of Belarusian patients with retinoblastoma. Seventy-eight point six per cent (78.6 %) of variants were detected by sequencing, 21.4 % were identified with the help of the MLPA and FISH methods. Among sporadic cases, germline RB1 variants were detected in 66.6 % (12/18) of cases. A full range of screening techniques is required to achieve high sensitivity of detection in retinoblastoma patients. Our study also provides new evidence that will inform patient management and genetic counseling.

   Serious side effects occur during therapy for childhood acute lymphoblastic leukemia (ALL), and survivors can experience long-term consequences. This study aimed at identifying patients who can be successfully treated with low treatment intensity combining clinical parameters and minimal residual disease (MRD) measurements. 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. ALL-MB studies used reduced-intensity therapy from the beginning, for standard risk (SR) patients no cyclophosphamide, a very low daunorubicin dose, no high dose of methotrexate, no cranial irradiation. In the ALL-MB 2008 study, 1702 children (49.1 % of all patients) were classified as SR due to favorable initial characteristics. These included 295 patients treated in institutions who took part in a pilot study on MRD measurement using flow cytometry on day 15 and/or at the end of induction (EOI). The most suitable time point for MRD measurement was EOI with threshold 0.1% in 90.5 % of the patients with excellent results: event-free survival of 95 % and overall survival of 97 %, that identified the large proportion of patients (more than 40 % of all ALL patients). The outcome of children with slower MRD response was significantly worse. Initial SR characteristics plus one single MRD measurement at EOI identify more than 40 % of all children with ALL who can be successfully treated with low-intensity regimens as used in the MB protocols.

   The COVID-19 pandemic continues to be a major public health threat worldwide. The course of this disease in immunocompromised patients is significantly different from that in healthy subjects, which is associated with the impossibility of virus elimination through their own adaptive immune response. Delayed immune reconstitution after hematopoietic stem cell transplantation (which may take months after the procedure) increases the risk of life-threatening COVID-19 infection necessitating a search for and application of new methods of treatment. T lymphocytes are critically important for viral infection control, and are necessary both for the direct elimination of Dmitry Rogachev National Medical Research Center of Pediatric Hematology, Oncology and Immunology of Ministry of Healthcare of the Russian Federation. The patient's parents gave consent to the use of their child's data, including photographs, for research purposes and in publications.

   Immune tolerance induction (ITI) is the principal method of inhibitor eradication in patients with hemophilia A. The existing guidelines generally recommend to start ITI with recombinant FVIII concentrates, but the presence of VWF in plasma-derived FVIII concentrates used for ITI may further influence the ITI success rate. A five-year-old male patient with hemophilia A with
inhibitors started ITI at our Center. The patient's parents gave consent to the use of their child's data, including photographs, for research purposes and in publications. The patient had an inhibitor titer of 0.52 BU/mL at the start of the ITI and a historical inhibitor peak titer of 28 BU/mL. The ITI was started 3.5 years after the first inhibitor detection. We chose a plasma-derived VWF/FVIII containing concentrate (Haemate P) and started the ITI at a dose of 100 units FVIII/kg once per day using central venous access, as proposed in the protocol developed by the United Kingdom Haemophilia Centre Doctors’ Organization (UKHCDO). The inhibitor titer rose to 5.5 BU/mL on day 10 and became negative on day 25 of the ITI. The FVIII trough level measured 24 h after the last dose was > 1 % on day 25. The patient discontinued prophylaxis with a bypassing agent. However, FVIII pharmacokinetics had not returned to normal yet, and the patient continued the ITI with the VWF/FVIII containing concentrate at the initial dose. We reassessed the parameters of FVIII pharmacokinetics 120, 270 and 300 days after the start of the ITI. The peak FVIII level, its half-life time and the trough level measured 24 h after the last dose gradually increased over time. On day 300, the half-life time was still less than 7 h (6 h), but the trough level at 24 h was as high as 12.6 %. So, the patient started tapering off the medicine (the dose was initially reduced to 75 units/kg once per day). No adverse events were observed during the 1 year of therapy. Starting from day 423, the patient was switched to prophylaxis with the concentrate administered at a dose of 50 IU/kg every other day. Here, we reported our experience with first-line ITI using the FVIII concentrate with a high content of VWF (Haemate P). A rapid decrease in the inhibitor titer and the normalization of the pharmacokinetic parameters of FVIII in the absence of significant bleeding or thrombotic complications were convincingly demonstrated. 

   Hematopoietic stem cell transplantation is a technology for the treatment of a wide range of oncological, hematological and a number of congenital diseases.

   The history of the use of bone marrow for medicinal purposes dates back more than 120 years.

   In 1891, 2 French doctors - Charles Brown-Séquard and Jacques D'Arsonval - gave the patient oral bone marrow to treat leukemias, naturally, without success. Approximately 50 years later, the first mention of intraosseous and intravenous injections of the bone marrow substrate appeared. Even then, a hypothesis was formulated that the patient's own immune system does not allow engraftment of donor cells. A very important discovery was made by Egon Lorenz in 1951, when it was first demonstrated that after irradiating mice with ionizing radiation and injecting them with bone marrow from other mice from the same litter, new bone marrow could take root and function. Naturally, it was difficult to prove the donor affiliation of a new hematopoiesis in the absence of knowledge about specific genetic markers, but the logic of the assumptions was built correctly.

   For the first time in modern history, bone marrow was transplanted to a patient by Edward Thomas at the Fred Hutchinson Cancer Research Center (USA) in 1957, and in 1958 Jean Dosset presented data on the existence of a human leukocyte antigen system (HLA system), which formed the basis further development of technology.

   The beginning of the modern era of transplantation is considered to be 1968, when Robert Good at the University Hospital of Minnesota (USA) performed the first bone marrow transplantation in a boy with primary immunodeficiency after selecting a related donor based on HLA typing data.

   Improving knowledge and development of new technologies in the field of genetics and cell engineering, combined with progress in the development of the latest, including targeted, drugs, are currently an argument for fundamentally new views on hematopoietic stem cell transplantation. Cell technologies are actively developing, certain successes have been achieved in the field of gene therapy. All this allows us to take a fresh look at some complex diseases, giving an objective chance for recovery to previously incurable patients.

   Now in the Russian Federation, hematopoietic stem cell transplantation is carried out in 8 transplant centers. In addition, construction is underway and it is planned to open at least 5 new regional clinics, in the structure of which transplantation activity is also planned.

   One of the fundamental differences between hematopoietic stem cell transplantation and many other medical technologies is the need for a long period of observation and treatment, a significant part of which should be carried out on an outpatient basis at the place of residence. Most of the problems that arise with patients at this stage can be solved by hematologists, oncologists, pediatricians or other specialists. However, in order to effectively identify and make timely and correct decisions, the doctor
often there is a lack of knowledge about the features of the technology and purely post-transplant clinical problems that need to be addressed.

   In this issue of the journal, we begin the column "School of Transplantation and Cellular Therapy". Here we plan to introduce you to transplantation, from the basics of technology to the analysis of certain topical clinical issues. FROM Taking into account the existing development vector of this method, we will also pay special attention to the modern view of cell therapy in the treatment of certain diseases, as well as a number of conditions where this technology already has a competitive advantage over pharmacotherapy. We very much hope that the information that we plan to share will be useful for a wide range of specialists.

   The first issue of the rubric is devoted to introductory issues of hematopoietic stem cell transplantation. We will talk about the indications, touch on the problem of histocompatibility and dwell on the fundamental issues of choosing the optimal pair donor-recipient.

   Ataxia-telangiectasia (АТ) represents a typical syndromic form of primary immunodeficiencies. Besides progressive neurological features, patients with AT have a high risk of malignancies, as well as autoimmune complications, with interstitial lung disease being one of the most frequent. AT is also characterized by a significant diagnostic delay, which was demonstrated in our case report. The patients’ parents gave their consent to the use of their children’s data, including photographs, for research purposes and in publications.

   Neuroblastoma (NB) is one of the most common embryonal tumors of childhood. About 40 % of all NB patients are stratified into the high-risk group and require multimodal therapy. The goal of induction treatment is a maximum reduction of the primary tumor and metastases. Response to induction therapy is an important prognostic factor affecting long-term survival. The protocol of our meta-analysis is registered in the International Prospective Register of Systematic Reviews (PROSPERO): ID-CRD42022311162. The PubMed, Google Scholar and Cochrane Library databases were searched for relevant studies published over the last 15 years (2007–2022). A total of 12 studies were selected for analysis where response to induction therapy was assessed in patients with high-risk NB in accordance with the International NB Response Criteria, and an analysis of the impact of response on overall (OS) and event-free (EFS) survival was carried out. The meta-analysis included 3431 patients: a good response to induction therapy (complete response / very good partial response) was achieved in 1702 patients, a poor response (partial response / mixed response / stable disease) – in 1729 patients. The patients with a good response had a 28 % lower relative risk (RR) of relapse / progression within 5 years of diagnosis compared with the patients with a poor response: RR = 0.72 (0.64 to 0.80), p-value for effect < 0.001, p-value for heterogeneity < 0.001, I2 = 65 %. The relative risk of death within 5 years of diagnosis was 31 % lower in the patients with a good response: RR = 0.69 (0.57 to 0.83), p-value for effect < 0.001, p-value for heterogeneity < 0.001, I2 = 78 %. A separate analysis of results of international cooperative groups (GPOH, COG and SIOPEN) also revealed a statistically significant relationship between partial response / mixed response / stable disease response to induction therapy and EFS (p < 0.001). The highest level of evidence was obtained for separate subgroups – GPOH (a moderate level of evidence for EFS) and SIOPEN (a moderate level of evidence for EFS and OS) – due to low clinical inconsistency (standardized response criteria and therapy) as well as low statistical inconsistency. The study had certain limitations that are described in detail in the article. Response to induction chemotherapy is an important factor that affects EFS and OS in patients with high-risk NB.

   The article presents a generalized analysis of information on the formation of a unified preventive environment in the healthcare system. The experience of specialists and medical organizations was analyzed, as well as the assessment of existing and developed methods.