Matched unrelated donor transplantation versus haploidentical transplantation with post-transplant cyclophosphamide in children with acute myeloid leukemia: a PDWP-EBMT study.

In children with acute myeloid leukemia (AML) who lack a human leukocyte antigen (HLA) identical sibling, the donor can be replaced with an HLA-matched unrelated donor (MUD) or a haploidentical donor (haplo). We compared outcomes of patients <18 years with AML in first and second complete remission (CR1 and CR2) undergoing a hematopoietic stem cell transplantation (HCT) either with a MUD with anti-thymocyte globulin (ATG) (N=420) or a haplo HCT with post-transplant cyclophosphamide (PT-CY) (N=96) after a myeloablative conditioning regimen (MAC) between 2011 and 2021, reported to the European Society for Blood and Marrow Transplantation. A matched pair analysis was performed to adjust for differences among groups. The final analysis was performed on 253 MUD and 95 haplo-HCT. In the matched cohort, median age at HCT was 11.2 and 10 years and median year of HCT was 2017 and 2018, in MUD and haplo-HCT recipients, respectively. The risk of grade III-IV acute graft-versus-host disease (aGVHD) was significantly higher in the haplo group (hazard ratio [HR]=2.33, 95% confidence interval [CI]: 1.18-4.58; P=0.01). No significant differences were found in 2 years overall survival (OS; 78.4% vs. 71.5%; HR=1.39, 95% CI: 0.84-2.31; P=0.19), leukemia-free survival (LFS; 72.7% vs. 69.5%; HR=1.22, 95% CI: 0.76-1.95; P=0.41), CI of relapse (RI; 19.3% vs. 19.5%; HR=1.14, 95% CI: 0.62-2.08; P=0.68) non-relapse-mortality (NRM; 8% vs. 11%; HR=1.39, 95% CI: 0.66-2.93; P=0.39) and graft-versus-host free relapse-free survival (GRFS; 60.7% vs. 54.5%, HR=1.38, 95% CI: 0.95-2.02; P=0.09) after MUD and haplo-HCT respectively. Our study suggests that haplo-HCT with PT-CY is a suitable option to transplant children with AML lacking a matched related donor.

Therapy results in pediatric Hodgkin lymphoma - does less mean better? Experience from a single children's oncology center.

Therapy results in pediatric Hodgkin lymphoma reflect remarkable progress in pediatric oncology. In the last decade, relevant development of new therapeutic options for children with refractory or relapsed disease has been made. In this study, we retrospectively analyzed therapy results and risk factors in children treated in a single oncology center according to five therapeutic protocols. Data from 114 children treated by a single institution between 1997 and 2022 were analyzed. Classic Hodgkin lymphoma therapy results were divided into four therapeutic periods: 1997-2009, 2009-2014, 2014-2019, and 2019-2022. For nodular lymphocyte-predominant Hodgkin lymphoma, data from one therapeutic protocol was analyzed. For the entire group, the 5-year probability of overall survival was 93.5%. There were no statistically significant differences between therapeutic periods. The occurrence of B symptoms at diagnosis and incidence of relapse were risk factors for death (p = 0.018 and p < 0.001). Relapse occurred in 5 cases. The 5-year probability of relapse-free survival for the entire group was 95.2%, without significant differences between groups. Patients treated between 1997 and 2009 had over a sixfold higher risk for events, defined as primary progression, relapse, death, or incidence of secondary malignancies (OR = 6.25, p = 0.086). The 5-year probability of event-free survival for all patients was 91.3%. Five patients died, and the most common cause of death was relapse. Modern therapeutic protocols in pediatric Hodgkin lymphoma are marked by excellent outcomes. Patients with disease relapses have a notably high risk of death, and the development of new therapeutic options for this group remains one of the main goals of current trials.

Infection With Saprochaete Clavata in Children After Hematopoietic Cell Transplantation.

Septic shock is a very rare manifestation of invasive fungal disease (IFD) in children after allogeneic hematopoietic cell transplantation (allo-HCT). The objective of this paper is analysis of two cases of pediatric patients with IFD caused by Saprochaete clavata after allo-HCT. Literature data on this infection in children and its outcome were also summarized. Infection with Saprochaete clavate presenting with symptoms of septic shock was being reported in 4 children, and 2 of them survived the infection. In conclusion, with quick diagnosis and quick treatment, the outcome of therapy of infection with Saprochaete clavata was successful.

Analysis of incidence and risk factors of the multidrug resistant gastrointestinal tract infection in children and adolescents undergoing allogeneic and autologous hematopoietic cell transplantation: a nationwide study.

The aim of this multi-center study was to evaluate the incidence, clinical course, and risk factors for bacterial multidrug-resistant (MDR) gastrointestinal tract infections (GTI) among children undergoing allogeneic and autologous hematopoietic cell transplantation. A total number of 175 pediatric patients (aged 1-18 years), transplanted between January 2018 and December 2019, who were tested for bacterial colonization/infection were enrolled into this multi-center analysis. Episodes of MDR GTI occurred in 77/175 (44%) patients. In multivariate analysis for higher GTI incidence, the following factors were significant: matched-unrelated donor (MUD) transplantation, HLA mismatch, presence of graft-versus-host disease (GVHD), and gut GVHD. The most common GTI were Clostridium difficile (CDI), multidrug-resistant Enterobacteriaceae (Klebsiella pneumoniae, Escherichia coli extended-spectrum ß-lactamase), and Enterococcus HLAR (high-level aminoglycoside-resistant). No MDR GTI-attributed deaths were reported. MDR GTI is a frequent complication after HCT among children, causes prolonged hospitalization, but rarely contributes to death. We identified risk factors of MDR GTI development in children, with focus on GVHD and unrelated donor and HLA mismatch. We conclude that the presence of Clostridiales plays an important anti-inflammatory homeostatic role and decreases incidence of GVHD or alleviate its course.

Prospective analysis of BKV hemorrhagic cystitis in children and adolescents undergoing hematopoietic cell transplantation.

BK virus is one of the most common causes of hemorrhagic cystitis (HC) in children undergoing hematopoietic cell transplantation (HCT). Viruses can be found in urine and serum samples of immunocompromised patients. Malignant diseases, age, cell source, day of granulocyte reconstitution, conditioning regimen, or use of total body irradiation may play an important role in BKV epidemiology, development of hemorrhagic cystitis course, and outcome. The aim of this study was to evaluate the incidence, clinical course, and risk factors for BKV-HC in children undergoing HCT. A total number of 133 patients who were prospectively tested for BKV colonization/infection were enrolled into this multicenter analysis. Episodes of BKV-HC occurred in 36/133 (27%) enrolled subjects. In a univariate analysis for BKV-HC incidence, the following factors were significant: age >5 years, peripheral blood transplantation, matched unrelated donor (MUD) transplantation, busulfan-cyclophosphamide-melphalan conditioning regimen, and acute myeloblastic leukemia (AML) diagnosis. Presence of acute graft-versus-host disease (aGVHD) in liver and gut GVHD was a significant risk factor of BKV-HC. No BKV-attributed deaths were reported. In multivariate analysis, the incidence of HC was significantly higher in patients with AML, age >5 years, MUD transplants, and children with GVHD. HC is a frequent complication after HCT among children causes prolonged hospitalization but rarely contributes to death. We identified risk factors of BKV-HC development in children, with focus on aGVHD: we concluded that excessive immune reaction connected with GVHD and immunosuppression drugs might play a pivotal role in the development of BKV-HC.

Varicella-zoster virus infection in the pediatric population with acute lymphoblastic leukemia in Poland.

Varicella-zoster virus (VZV) infection in pediatric hemato-oncology patients can be a therapeutic problem when children are exposed to immunosuppression. The aim of this study is to evaluate the incidence of VZV infection, antiviral therapy and outcome in children with ALL treated in polish hemato-oncological centers between 2012 and 2019 years. This study included medical records of 1874 patients, aged 1 to 18 years, with newly diagnosed acute lymphoblastic leukemia. During chemotherapy, 406 children out of 1874 (21.6%) experienced viral infections. The incidence of VZV infection in the whole group children with ALL was 1.8%. Among them, 34 (8.4%) patients were diagnosed with VZV infection. Thirty-five episodes of viral infections were identified. The median time of VCV therapy was 12 days. Herpes zoster infection occurred in 24 (70.6%) children, and varicella in 10 (29.4%) ones. The average time from the start of chemotherapy to the appearance of herpes zoster was 7.26 ± 4.05 months. VZV infection occurred mainly during the maintenance therapy, the reinduction and induction phases. There was no correlation between steroid dosage or type and subsequent zoster. The total lymphocyte count of these patients on the first day of zoster was reduced. No serious complications were observed due to this infection. All patients survived. In conclusion, a low incidence of VZV infection was observed among pediatric patients with ALL in Poland. This analysis indicates that currently used therapeutic methods are effective in children with cancer and VZV infection. The main focus should be on the prevention of delayed chemotherapy.

Infectious complications after hematopoietic stem cell transplantation for primary immunodeficiency in children: A multicenter nationwide study.

PURPOSE: The aim of this nationwide study was to evaluate the characteristics of bacterial infections (BI), invasive fungal disease (IFD), and viral infections (VI) in pediatric patients with PID after allogeneic hematopoietic stem cell transplantation (allo-HSCT). PATIENTS AND METHODS: In total, 114 HSCT recipients were enrolled into the study. At least one infectious complication (IC) was diagnosed in 60 (52.6%) patients aged 0.1-17.7 years, that is, 59.5% with SCID and 49.4% with non-SCID. RESULTS: Among 60 HSCT recipients diagnosed with at least one IC, 188 episodes of infectious complications (EIC) were recorded, that is, 46.8% of BI, 41.5% of VI, and 11.7% of proven/probable IFD. According to PID and HSCT donor type, the incidence of EIC was comparable (P = .679). The localization of infections differed significantly due to PID type (P = .002). After each HSCT donor type, the most common site of infection was GI. Overall, BI caused by Gram-positive strains (59.1%) were prevalent, especially Staphylococcaceae. The multidrug-resistant (MDR) pathogens were diagnosed in 52.3%, especially ESBL + Enterobacteriaceae. The profile of VI was comparable for SCID and non-SCID patients (P = .839). The incidence of IFD was comparable for each PID and HSCT donor type. Survival after infection was 91.5% and was comparable for PID and HSCT donor type. CONCLUSIONS: The rate of patients diagnosed with IC among pediatric PID-HSCT recipients did not depend on PID type, but rather on HSCT donor type. The localization of IC depended on PID and HSCT donor type. Within bacterial infections, predominated Gram-positive strains and the MDR pathogens were responsible for more than half of EIC.

The Successful Sequential Use of Plerixafor and Eltrombopag For Hematopoietic Cell Transplantation in a Child With High-risk Neuroblastoma.

High-dose chemotherapy with autologous hematopoietic stem cell transplantation improves event-free survival in patients with high-risk neuroblastoma. However, in heavily pretreated patients, poor marrow function can be an obstacle in the successful proceeding of therapy. Priming with plerixafor plus filgrastim is an option for effective mobilization and collection of stem cells. In addition, thrombopoietin agonist eltrombopag can improve the outcome of posttransplantation thrombocytopenia and poor graft function in the posttransplant setting. We describe a case of a child with high-risk neuroblastoma, for whom plerixafor and eltrombopag were used as an effective and safe supportive therapy.

Successful Management of Unusual Multiple Gut Colonization With Extremely Drug-resistant Bacteria in an Infant Undergoing Hematopoietic Cell Transplantation.

Enterobacterales represent a serious threat to transplant patients due to their increase frequency of carbapenem resistance and wide spreading. We present a case of an infant with acute lymphoblastic leukemia undergoing hematopoietic stem cell transplantation. Before transplantation an unusual double colonization of the gastrointestinal tract with extremely resistant Escherichia coli and Klebsiella pneumoniae strains producing metallo-beta-lactamase was diagnosed. Respective epidemiologic management was implemented, based on the strict reverse isolation in patient-protective environment, and intensified antimicrobial surveillance. After granulocyte recovery, no extremely drug-resistant strains were found, and no case of isolation and/or transmission of carbapenem-resistant bacteria has been identified in the transplant center during the following 6 months.

Age-dependent determinants of infectious complications profile in children and adults after hematopoietic cell transplantation: lesson from the nationwide study.

Incidence and outcome of microbiologically documented bacterial/viral infections and invasive fungal disease (IFD) in children and adults after hematopoietic cell transplantation (HCT) were compared in 650 children and 3200 adults in multicenter cross-sectional nationwide study. Infections were diagnosed in 60.8% children and 35.0% adults, including respectively 69.1% and 63.5% allo-HCT, and 33.1% and 20.8% auto-HCT patients. The incidence of bacterial infections was higher in children (36.0% vs 27.6%; p < 0.0001). Infections with Gram-negative bacteria were more frequent than Gram-positives in adults (64.6% vs 44.8%; p < 0.0001). Outcome of bacterial infections was better in children (95.5% vs 91.4%; p = 0.0011). The IFD incidence (25.3% vs 6.3%; p < 0.0001) and outcome (88.0% vs 74.9%; p < 0.0001) were higher in children. The incidence of viral infections was higher in children after allo-HCT (56.3% vs 29.3%; p < 0.0001), and auto-HCT (6.6% vs 0.8%; p < 0.0001). Outcome of viral infections was better in children (98.6% vs 92.3%; p = 0.0096). Infection-related mortality was 7.8% in children and 18.4% in adults (p < 0.0001). No child after auto-HCT died of infection. Adult age, mismatched transplants, acute leukemia, chronic GVHD, CMV reactivation, infection with Gram-negatives, and duration of infection > 21 days were risk factors for death from infection. In conclusion, pediatric patients have 2.9-fold higher incidence and 2.5-fold better outcome of infections than adults after HCT.

Infection profile in children and adolescents with bone marrow failures treated with allogeneic hematopoietic stem cell transplantation.

BACKGROUND: The objective of the study was to analyze the profile of infections in children with BMF following alloHCT. METHODS: Data of 169 consecutive children with inherited and acquired BMF treated with alloHCT between 2012 and 2017 in Polish pediatric transplant departments were analyzed in registry-based retrospective study, with respect to the type of infection, and clinical outcome. RESULTS: At least 1 infection was diagnosed in 107/169 patients (60.4%). In total, 182 infections were diagnosed. The most common were VI (96; 52.7%), followed by BI (71; 39.0%), and FI (15; 8.2%), P < .001. The most common etiological factors of VI were as follows: CMV (38.5%), EBV (22.9%), and BK virus (24%); while of BI were as follows: Staphylococcus spp. (17; 23.9%), Enterococcus faecium (10; 14.1%), and Klebsiella pneumoniae (9; 12.7%). No difference was found between the occurrence of infections with respect to donor type, graft source, and conditioning type. GvHD had no impact on the incidence of VI, BI, and FI. Fifteen FI were diagnosed in 12 patients, of which 14 FI were diagnosed in children transplanted for FA. Of total 107 children, 9 died (8.4%), of which 4 (3.7%) due to infections: bacterial sepsis (2) and invasive FI (2). CONCLUSION: Infections in children with BMF following alloHCT remain an important cause of morbidity. Children with FA had high incidence of FI. In our analysis, aGvHD had no impact on the occurrence on infections, although the study was not strong enough to prove such a difference.

Infectious profile in children with ALL during chemotherapy: A report of study group for infections.

INTRODUCTION: The treatment-related mortality in currently published studies of acute lymphoblastic leukemia (ALL) in children is 2-4%, mainly due to infections. The aim of the study was to analyse the incidence, epidemiology, profile of infection and the death rate in children with ALL. PATIENTS AND METHODS: The retrospective analysis included 1363 patients, aged 1-18 years, with newly diagnosed ALL, who were treated in 17 pediatric hematology centers between 2012 and 2017 in Poland. The patients received therapy according to the ALL IC-BFM 2002 and 2009 (International Berlin-Frankfurt-Munster Study Group) protocols. RESULTS: In our study, 726 out of 1363 (53.2%) children were reported to have a microbiologically documented bacterial infection during chemotherapy. 1511 episodes of these infection were diagnosed. A total number of 251/1363 (18.4%) children experienced a viral infection. 304 episodes were documented by PCR test (polymerase chain reaction). A fungal infection was reported in 278 (20.4%) children, including 10.1% of probable, 6.0% of proven, 83% of possible diagnosis. A higher frequency of fungal infection was noted in the recent years. In our material, the rate of death was 2.4%, mainly due to fungal infection. CONCLUSIONS: Our results present the epidemiology of infectious disease in the Polish ALL patient population. The most frequent were bacterial infections, followed by fungal and viral ones. Similar to the previously published data, the mortality rate in our material was 2.4%.

Epidemiology and outcome of invasive fungal disease in children after hematopoietic cell transplantation or treated for malignancy: Impact of national programme of antifungal prophylaxis.

The objective of the study was the analysis of incidence and outcome of invasive fungal disease (IFD) in children treated for malignancy (PHO, paediatric hematology-oncology) or undergoing hematopoietic cell transplantation (HCT) over a period of six consecutive years in nationwide study. A total number of 5628 patients with newly diagnosed malignancies and 971 patients after HCT (741 allo-HCT and 230 auto-HCT) were screened for infectious complications in biennial reports. IFD incidence was lower among PHO patients: 8.8% vs 21.2% (P < .0001) and survival from IFD was better: 94.2% vs 84.1% (P < .0001). Auto-HCT patients had lower incidence (10.9% vs 24.4%) and lower mortality than allo-HCT patients. Introduction of national antifungal prophylaxis programme in HCT and acute leukaemia patients decreased incidence of IFD in HCT (from 23.1% to 13.4%) and AML on conventional chemotherapy (from 36% to 23%) but not in ALL patients during chemotherapy. In multivariate analysis, the incidence of IFD was higher in patients after HCT, diagnosed for ALL, AML or NHL, and in patients > 10 years old. Factors contributing to death with infection were as follows: undergoing HCT, diagnosis of acute leukaemia (ALL or AML) and duration of treatment of infection > 21 days. In conclusion, the incidence of IFD in allo-HCT and in AML patients on chemotherapy has decreased after introduction of national programme of antifungal prophylaxis, while the incidence of IFD in ALL patients on chemotherapy did not change significantly. The outcome of IFD both in PHO and HCT patients has largely improved in comparison with historical international data.

Complex profile of multiple hepatobiliary and gastrointestinal complications after hematopoietic stem cell transplantation in a child with Nijmegen breakage syndrome.

Patients with Nijmegen breakage syndrome (NBS) can develop life-threatening immunodeficiency, which should be treated with hematopoietic stem cell transplantation (HSCT). We report the case of a 14-year-old girl with NBS who due to an increasing number of severe complications was referred for HSCT from a matched unrelated donor. After reduced-intensity conditioning and transplantation of peripheral blood hematopoietic cells, during the early post-transplant period (days 0-30), the girl suffered from severe mucositis, fever episodes, mild acute renal injury and facial vasculitis. All these complications were managed successfully. During the intermediate post-transplant period (days 30-100) a number of hepatic and gastrointestinal complications occurred, including cholecystitis, cholelithiasis with choledocholithiasis, pancreatitis as well as acute bleeding from the lower gastrointestinal tract caused by rectal and recto-sigmoid junction ulcers. All the obstacles were obviously attributable both to the primary congenital disease, its complications, and transplantation itself. We overcame these complications and treated the patient with the best possible and safe methods. The multidisciplinary approach based on combined surgical, endoscopic and conservative management of multiple post-transplant complications was successful for the patient.

Impact of prophylaxis with rituximab on EBV-related complications after allogeneic hematopoietic cell transplantation in children.

Background: Children undergoing allo-HCT are at high risk of EBV-related complications. The objective of the study was to analyze the impact of prophylactic post-transplant rituximab on EBV infection and EBV-PTLD in children after allo-HCT, to determine the risk factors for the development of EBV infection and EBV-PTLD and to determine their outcomes. Additionally, the impact of EBV-driven complications on transplant outcomes was analyzed. Methods: Single center retrospective analysis of EBV-related complications in pediatric population undergoing allo-HCT, based on strategy of prophylaxis with rituximab. Overall 276 consecutive children, including 122 on prophylaxis, were analyzed for EBV-driven complications and transplant outcomes. Results: Prophylaxis with rituximab resulted in significant reduction of EBV infection (from 35.1% to 20.5%; HR=2.7; p<0.0001), and EBV-PTLD (from 13.0% to 3.3%; HR=0.23; p=0.0045). A trend for improved survival was also observed (HR=0.66; p=0.068), while non-relapse mortality was comparable in both cohorts. The peak value of viral load was a risk factor in the development of EBV-PTLD: 10-fold higher peak viral load in comparison to the baseline 104 copies/mL, caused a 3-fold (HR=3.36; p<0.001) increase in the risk of EBV-PTLD. Rituximab treatment was effective as a preemptive therapy in 91.1%, and in 70.9% in EBV-PTLD. Patients who developed PTLD had dismal 5-year overall survival (29% vs 60%; p<0.001), and an increased risk of relapse (72% vs 35%; p=0.024). Conclusions: Rituximab for prophylaxis of EBV infection and EBV-PTLD was highly effective in pediatric population. Treatment of EBV-PTLD was successful in 70%, however the occurrence of EBV-PTLD was associated with an increased risk of relapse of primary malignant disease.

Pre-Exposure Prophylaxis and Treatment with Tixagevimab/Cilgavimab for COVID-19 among Immunocompromised Pediatric Patients.

Background: Patients treated with hemato-oncological malignancies (HO) or undergoing cellular therapies such as hematopoietic stem cell transplantation (HSCT) or chimeric antigen receptor T cells (CAR-T) were significantly affected by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Despite the success of SARS-CoV-2 vaccination, immunocompromised patients remain at increased risk for severe coronavirus disease (COVID-19), rendering this group of population a high priority for additional prevention and treatment options. Tixagevimab and Cilgavimab (TIXA/CILGA, AZD7442, Evusheld®) is a combination of two fully human, long-acting monoclonal antibodies. TIXA/CILGA have been approved as pre-exposure prophylaxis and treatment in patients at risk of severe disease with impaired vaccine response. Our objective was to describe the efficacy and safety among immunocompromised pediatric patients. Methods: This was an observational multicenter cohort study of immunocompromised pediatric patients receiving TIXA/CILGA conducted at nine Polish centers of Pediatric Oncology, Hematology and Bone Marrow Transplantation. We analyzed patients in two groups; those treated with HO and those undergoing cellular therapies: HSCT or CAR-T cells. In addition, two other cohorts were identified: patients given TIXA/CILGA as pre-exposure prophylactic and therapeutic intervention. Results: A total of 78 patients were evaluated during the study period: 69 (88.5%) received TIXA/CILGA as pre-exposure prophylaxis and 9 (11.5%) as a treatment strategy. A total of 52 (66.6%) patients were treated with standard chemotherapy at HO departments; 21 (27%) underwent HSCT, and 5 (6.4%) received CAR-T cell therapy. All children with COVID-19 receiving TIXA/CILGA presented a mild degree of severity. The most common clinical manifestations were fever, cough and coryza. At least one adverse event (AE) was reported in two (3.8%) patients excluding standard injection site reactions. Reported AEs were mild or moderate in intensity. One child reported mild myalgia and one reported moderate bone pain and weakness. Conclusions: In our observational multicenter cohort study, we explored the use of TIXA/CILGA as pre-exposure prophylaxis and treatment for COVID-19 among immunocompromised pediatric patients. While our findings suggest a potential benefit in preventing and managing COVID-19 in this vulnerable population, it is important to note the study's non-comparative design. Our results highlight the need for well-designed clinical trials to confirm these observations and further assess the efficacy and safety of TIXA/CILGA in immunocompromised children.

Infections with Klebsiella pneumoniae in Children Undergoing Anticancer Therapy or Hematopoietic Cell Transplantation: A Multicenter Nationwide Study.

Background:Klebsiella pneumoniae is a nosocomial pathogen that causes severe infections in immunocompromised patients. The aim of the study was to conduct a microbiological and clinical analysis of K. pneumoniae infections in children with malignancies or undergoing hematopoietic cell transplantation in Poland. Methods: We conducted a retrospective, multicenter study including children and adolescents under 19 years old treated between 2012 and 2021. We analyzed patients' characteristics, microbiological data, and the outcomes of antibiotic therapy. Results: A total of 9121 newly diagnosed children were treated for malignancy and 1697 pediatric patients underwent hematopoietic cell transplantation. K. pneumoniae infections were diagnosed in 527 patients. Their overall incidence was 4.86% in pediatric hematology and oncology patients and 4.95% in patients who underwent hematopoietic cell transplantation. The incidence of infection was higher in patients with acute leukemia than with solid tumors (7.8% vs. 4.1%; OR = 2.0; 95% CI = 1.6-2.4; p < 0.0001). The most frequent source of infection was in the urinary tract at 55.2%. More than 57% of K. pneumoniae strains were extended-spectrum ß-lactamase-positive and almost 34% were multidrug-resistant. Infections with K. pneumoniae contributed to death in 3.22% of patients. Conclusions: K. pneumoniae is one of the most critical pathogens in children suffering from malignancies or undergoing hematopoietic cell transplantation. The incidence of multidrug-resistant K. pneumoniae strains is increasing and contributing to poor clinical outcome.

Incidence of bacterial and fungal infections in Polish pediatric patients with acute lymphoblastic leukemia during the pandemic.

The most common complications related to the treatment of childhood acute lymphoblastic leukemia (ALL) are infections. The aim of the study was to analyze the incidence and mortality rates among pediatric patients with ALL who were treated in 17 Polish pediatric hematology centers in 2020-2021 during the pandemic. Additionally, we compared these results with those of our previous study, which we conducted in the years 2012-2017. The retrospective analysis included 460 patients aged 1-18 years with newly diagnosed ALL. In our study, 361/460 (78.5%) children were reported to have microbiologically documented bacterial infections during chemotherapy. Ten patients (2.8%) died due to sepsis. Fungal infections were reported in 99 children (21.5%), of whom five (5.1%) died due to the infection. We especially observed an increase in bacterial infections during the pandemic period compared to the previous study. The directions of our actions should be to consider antibiotic prophylaxis, shorten the duration of hospitalization, and educate parents and medical staff about complications (mainly infections) during anticancer therapy. It is necessary to continue clinical studies evaluating infection prophylaxis to improve outcomes in childhood ALL patients.

Bortezomib has little ex vivo activity in chronic myeloid leukemia: individual tumor response testing comparative study in acute and chronic myeloid leukemia.

AIM OF THE STUDY: Resistance to imatinib is one of the most important issues in treatment of chronic myeloid leukemia (CML) patients. The objective of the study was to analyze the ex vivo drug resistance profile to bortezomib and 22 other antileukemic drugs, including three tyrosine kinase inhibitors (TKIs), in CML in comparison to acute myeloid leukemia (AML). MATERIAL AND METHODS: A total of 82 patients entered the study, including 36 CML and 46 AML adults. Among CML patients, 19 had advanced disease, 16 were resistant to imatinib, and 6 had ABL-kinase domain mutations. The ex vivo drug resistance profile was studied by the MTT assay. RESULTS: CML CELLS WERE MORE RESISTANT THAN AML BLASTS TO THE FOLLOWING DRUGS: prednisolone, vincristine, doxorubicin, etoposide, melphalan, cytarabine, fludarabine, thiotepa, 4-HOO-cyclophosphamide, thioguanine, bortezomib, topotecan, and clofarabine. CML cells were 2-fold more sensitive to busulfan than AML cells. CML patients with clinical imatinib resistance had higher ex vivo resistance to vincristine, daunorubicin, etoposide, and busulfan. No significant differences to all tested drugs, including TKIs, were observed between CML patients with non-advanced and advanced disease. CML patients with mutation had higher ex vivo resistance to vincristine, idarubicin, thiotepa, and busulfan. CONCLUSIONS: CML cells are ex vivo more resistant to most drugs than acute myeloid leukemia blasts. Busulfan is more active in CML than AML cells. In comparison to AML cells, bortezomib has little ex vivo activity in CML cells. No differences between CML subgroups in sensitivity to 3 tested TKIs were detected.

Case report: Cellular therapy for hydroa vacciniforme-like lymphoproliferative disorder in pediatric common variable immunodeficiency with chronic active Epstein-Barr virus infection.

Hydroa vacciniforme-like lymphoproliferative disorder (HV-LPD) is a cutaneous form of chronic active Epstein-Barrvirus (EBV) infection, which can develop into the extremely rare systemic lymphoma. Patients with Inborn errors of immunity (IEI), such as common variable immunodeficiency (CVID), are at higher risk of developing a severe course of infections especially viral and malignancies than the general population. The aim of the study was to present complex diagnostic and therapeutic management of HV-LPD. The clinical diagnosis was confirmed at the histological and molecular level with next generation sequencing. HV-LPD was diagnosed in a patient with CVID and chronic active Epstein-Barr virus (CAEBV) infection. The patient was refractory to CHOP chemotherapy and immunosuppressive treatment in combination with antiviral drugs (prednisone, bortezomib, gancyclovir). The third-party donor EBV-specific cytotoxic T cells (EBV-CTL, tabelecleucel) were used, which stabilised the disease course. Finally, matched unrelated donor hematopoietic cell transplantation (MUD-HCT) was performed followed by another cycle of EBV-CTL.