Highly sensitive chimerism detection in blood is associated with increased risk of relapse after allogeneic hematopoietic cell transplantation in childhood leukemia

Analysis of chimerism in blood post‐HCT using STR‐PCR is routinely applied in parallel with quantification of MRD to predict relapse of leukemia. RQ‐PCR chimerism is 10‐ to 100‐fold more sensitive, but clinical studies in children are sparse. We analyzed IMC in blood samples following transplantation for acute lymphoblastic or myeloid leukemia in 56 children. IMC was defined as a minimum increase of (a) 0.1% or (b) 0.05% recipient DNA between two samples. The risk of relapse was higher in children with IMC of both 0.1% and 0.05% compared to children without IMC (HR 12.8 [95% CI: 3.9‐41.4; P < .0001] and 7.6 [95% CI: 2.2‐26.9; P < .01], respectively). The first IMC was detected at a median of 208 days prior to relapse. The 5‐year cumulative incidence of relapse for children with a single IMC was 45.5% (CI 12.3‐74.4) and 41.0% (14.2‐66.6) for IMC above 0.1% and 0.05%, respectively. However, in 47 and 38 children never attaining IMC > 0.1% and >0.05%, 10 and 8 children relapsed, respectively. In a landmark analysis, no association was found between IMC prior to 90 days post‐HCT and subsequent relapse by either classification of IMC and AUC for RQ‐PCR chimerism was 54.2% (95 CI 27.7‐ 84.8). Although limited by a retrospective design, these results indicate that monitoring of RQ‐PCR chimerism in peripheral blood may have a role in early detection of relapse in acute childhood leukemia .     

Comparison of survival outcome between donor types or stem cell sources for childhood acute myeloid leukemia after allogenic hematopoietic stem cell transplantation: A multicenter retrospective study of Study Alliance of Yeungnam Pediatric Hematology‐oncology

We compared transplant outcomes between donor types and stem cell sources for childhood acute myeloid leukemia (AML). The medical records of children with AML in the Yeungnam region of Korea from January 2000 to June 2017 were reviewed. In all, 76 children with AML (male‐to‐female ratio = 46:30) received allogenic hematopoietic stem cell transplantation (allo‐HSCT). In total, 29 patients received HSCT from either a matched‐related donor or a mismatched‐related donor, 32 patients received an unrelated donor, and 15 patients received umbilical cord blood. In term of stem cell sources, bone marrow was used in 15 patients and peripheral blood in 46 patients. For all HSCT cases, the 5‐year overall survival (OS) was 73.1% (95% CI: 62.7‐83.5) and the 5‐year event‐free survival (EFS) was 66.1% (95% CI: 54.5‐77.7). There was no statistical difference in 5‐year OS according to the donor types or stem cell sources (P = .869 and P = .911). There was no statistical difference in 5‐year EFS between donor types or stem cell sources (P = .526 and P = .478). For all HSCT cases, the 5‐year relapse rate was 16.1% (95% CI: 7.3‐24.9) and the 5‐year non‐relapse mortality (NRM) was 13.3% (95% CI: 5.1‐21.5). There was no statistical difference in the 5‐year relapse rate according to the donor types or stem cell sources (P = .971 and P = .965). There was no statistical difference in the 5‐year NRM between donor types or stem cell sources (P = .461 and P = .470).     

Clinical resistance associated with a novel MAP2K1 mutation in a patient with Langerhans cell histiocytosis

Patients with Langerhans cell histiocytosis (LCH) harbor BRAF V600E and activating mutations of MAP2K1/MEK1 in 50% and 25% of cases, respectively. We evaluated a patient with treatment‐refractory LCH for mutations in the RAS‐RAF‐MEK‐ERK pathway and identified a novel mutation in the MAP2K1 gene resulting in a p.L98_K104 > Q deletion and predicted to be auto‐activating. During treatment with the MEK inhibitor trametinib, the patient's disease showed significant progression. In vitro characterization of the MAP2K1 p.L98_K104 > Q deletion confirmed its effect on cellular activation of the ERK pathway and drug resistance.     

Chimerism analysis in clinical practice and its relevance for the detection of graft rejection and malignant relapse in pediatric hematopoietic stem cell transplant patients

Chimerism and clinical outcome data from 244 hematopoietic stem cell transplants in 218 children were retrospectively analyzed to assess their relevance for the detection of graft rejection and malignant relapse. Patients transplanted for a non‐malignant disease had significantly higher proportions of residual recipient T cells in peripheral blood at one, three, and six months compared with patients transplanted for malignant disease. Recipient T‐cell levels were below 50% at one month after transplantation in most patients (129 of 152 transplants). Graft rejection occurred more frequently in the group of patients with high levels of recipient cells at one month (10 graft rejections in the 23 patients with recipient T cells >50% at one month as compared to seven graft rejections occurred in 129 patients with recipient T cells <50% (p < 0.001). Multilineage chimerism data in 87 children with leukemia at one, three, and six months after transplantation were not correlated with subsequent relapse of malignant disease. In conclusion, early analysis of lineage‐specific chimerism in peripheral blood can be used to identify patients who are at high risk of graft rejection. However, the efficacy of early chimerism analysis for predicting leukemia relapse was limited.     

Increased p53 protein expression as a potential predictor of early relapse after hematopoietic stem cell transplantation in children with acute myelogenous leukemia

Dysregulation of genes involved in the cell cycle such as TP53, P21, P16, and PTEN plays a key role in oncogenesis. We have earlier reported increased expression of the TP53 encoded protein p53, in bone marrow samples from pediatric patients with more aggressive, rare chronic myeloid malignancies. The aim of this study was to investigate protein expression of p53, p21, p16, and PTEN before and after HSCT in pediatric patients with AML and evaluate whether any potential alterations could predict relapse after HSCT. Paraffin‐embedded bone marrow samples from 34 pediatric patients with AML were collected retrospectively from time of diagnosis as well as pre‐ and post‐HSCT. IHC was performed on tissue microarrays with antibodies against p53, p21, p16, and PTEN. Study material was analyzed by independent t‐tests and nonlinear regression. t‐Tests showed a statistical significant difference in p53 (p = 0.010) with overexpression in the group of patients who relapsed compared to the relapse‐free patients at >3–6 months post‐HSCT. Analysis of p53 protein expression by IHC may be a potential predictor for relapse after HSCT in children with AML.     

Treatment‐related mortality in relapsed childhood acute lymphoblastic leukemia

1 Background

Treatment of relapsed childhood acute lymphoblastic leukemia (ALL) is particularly challenging due to the high treatment intensity needed to induce and sustain a second remission. To improve results, it is important to understand how treatment‐related toxicity impacts survival.

2 Procedure

In this retrospective population‐based study, we described the causes of death and estimated the risk for treatment‐related mortality in patients with first relapse of childhood ALL in the Nordic Society of Paediatric Haematology and Oncology ALL‐92 and ALL‐2000 trials.

3 Results

Among the 483 patients who received relapse treatment with curative intent, we identified 52 patients (10.8%) who died of treatment‐related causes. Twelve of these died before achieving second remission and 40 died in second remission. Infections were the cause of death in 38 patients (73.1%), predominantly bacterial infections during the chemotherapy phases of the relapse treatment. Viral infections were more common following hematopoietic stem cell transplantation (HSCT) in second remission. Independent risk factors for treatment‐related mortality were as follows: high‐risk stratification at relapse (hazard ratio [HR] 2.2; 95% confidence interval [CI] 1.3–3.9; P < 0.01), unfavorable cytogenetic aberrations (HR 3.4; 95% CI 1.3–9.2; P = 0.01), and HSCT (HR 4.64; 95% CI 2.17–9.92; P < 0.001). In contrast to previous findings, we did not observe any statistically significant sex or age differences. Interestingly, none of the 17 patients with Down syndrome died of treatment‐related causes.

4 Conclusions

Fatal treatment complications contribute significantly to the poor overall survival after relapse. Implementation of novel therapies with reduced toxicity and aggressive supportive care management are important to improve survival in relapsed childhood ALL.     

Effects and long‐term follow‐up of using umbilical cord blood–derived mesenchymal stromal cells in pediatric patients with severe BK virus‐associated late‐onset hemorrhagic cystitis after unrelated cord blood transplantation

This is a retrospective study to evaluate the efficacy and safety of umbilical cord blood–derived mesenchymal stromal cells (MSCs) for the treatment of pediatric patients with severe BK virus–associated late‐onset hemorrhagic cystitis (BKV‐HC) after unrelated cord blood transplantation (UCBT). Thirteen pediatric patients with severe BKV‐HC from December 2013 to December 2015 were treated with MSCs. The number of MSCs transfused in each session was 1 × 10⁶/kg once a week until the symptoms improved. The median follow‐up time was 1432 (89‐2080) days. The median frequency of MSC infusion was 2 (1‐3), with eight cured cases and five effective cases; the total efficacy rate was 100%. The copy number of urine BKV DNA was 4.43 (0.36‐56.9) ×10⁸/mL before MSC infusion and 2.67 (0‐56.3) ×10⁸/mL after MSC infusion; the difference was not significant (P = .219). There were no significant differences in the overall survival, disease‐free survival, and the incidence of relapse and acute and chronic graft‐versus‐host disease between the MSC infusion group and non‐MSC infusion group. There was also no significant difference in the cytomegalovirus, Epstein‐Barr virus (EBV), and fungal and bacterial infection rates between the two groups. Although umbilical cord blood–derived MSCs do not reduce the number of BKV DNA copies in the urine, the cells have a high efficacy rate and minimal side effects in treating severe BKV‐HC after UCBT among pediatric patients. MSCs do not affect the rates of relapse, long‐term infection, or survival of patients with leukemia.     

Epidemiology and outcome of chronic high Epstein‐Barr viral load carriage in pediatric kidney transplant recipients

The development of EBV infection and PTLD is normally associated with a high EBV viral load in peripheral blood. Observations have previously identified existence of a CHL carrier state that demonstrated variable outcomes based upon the organ which was transplanted. Data defining the incidence and outcome of CHL in pediatric KTx are not well described. The charts of children undergoing isolated KTx at Children's Hospital of Pittsburgh between January 2000 and December 2014 were retrospectively reviewed. EBV loads in the peripheral blood were routinely measured as part of surveillance protocols at our center. CHL was defined as the presence of high load for >50% of samples for ≥6 months. PTLD was defined histologically using WHO definitions. Of 188 isolated KTx recipients, we identified a total of 16 (8%) children who developed CHL carrier state. No patient developed EBV‐driven late‐onset PTLD. Age at the time of KTx was significantly lower in the CHL group (median 3.9 years, interquartile range: IQR 2.9‐6.6, P = .0004). Children in the CHL group were more likely to be EBV‐seronegative prior to KTx (94%, 15/16), compared to the UVL and LVL groups (55% and 50%, respectively, P < .002). The median duration of CHL carrier state was 20 months (IQR 10.7‐35.8). Fifteen of the 16 CHL carriers experienced spontaneous resolution of CHL carrier state. Children in the CHL group were younger at the time of primary EBV infection (P = .023). Finally, antiviral medication was not effective in either preventing or decreasing the EBV viral load in blood (P = .84). Overall incidence of late‐onset PTLD is very low compared to heart and intestinal transplant, even though KTx recipients can develop CHL carrier state. The CHL carriers in KTx recipients were EBV‐seronegative prior to transplant and were younger both at the time of KTx and at the time of primary EBV infection compared to those in the UVL and HVL groups. Antivirals did not prevent EBV infection or decrease EBV viral loads.     

Glucocorticoid‐Induced Proliferation in Untreated Pediatric Acute Myeloid Leukemic Blasts

We evaluated the in vitro glucocorticoid (GC) responsiveness of 117 pediatric acute myeloid leukemia cells by considering GC resistance, GC‐induced proliferation, and GC‐induced differentiation. None of the samples was highly GC sensitive, and only 15% were intermediately sensitive. GC‐induced differentiation was not observed, while GC‐induced proliferation was observed in 27% of the samples. Samples with French‐American‐British classification (FAB) type M5 or activating Fms‐like tyrosine kinase 3 (FLT3) mutations were significantly more prone to this phenomenon. Although we could not confirm this in our study, if induced proliferation in vitro is paralleled in vivo, GCs during consolidation may have adverse effects on minimal residual leukemic cells, which might increase relapse risk.     

A single supratentorial high‐grade neuroepithelial tumor with two distinct BCOR mutations,exceptionally long complete remission and survival

Here, we present a patient with high‐grade neuroepithelial tumors with mutations in the BCL6 corepressor BCOR (HGNET‐BCOR), a rare, highly malignant brain tumor with poor prognosis. The patient underwent gross total tumor resection (GTR), high‐dose chemotherapy, and, after local relapse, GTR, proton radiation, and chemotherapy. After a 7.5 year‐long complete remission, the tumor recurred locally, was treated by GTR, and responded to temozolomide treatment. In addition to an internal tandem duplication in BCOR common to the majority of HGNET‐BCOR cases, molecular analysis revealed a second BCOR mutation in this tumor: a frame shift mutation. The combination of these mutations was associated with relatively low BCOR expression compared to other HGNET‐BCOR cases.     

Post‐transplant recurrence of atypical hemolytic uremic syndrome in a patient with thrombomodulin mutation

HUS is characterized by hemolytic anemia, thrombocytopenia, and acute renal failure. While “typical” HUS is usually associated with Shiga toxin‐producing Escherichia coli infections and recovers in the majority of cases, aHUS is caused by mutations of complement components or antibodies against CFH leading to uncontrolled activation of alternative complement pathway and often to ESRD. Recently, THBD gene mutations have been reported in aHUS. Theoretically, the risk of disease recurrence after renal transplantation should be low because THBD is primarily a membrane‐bound protein expressed by endothelial cells; however, a small proportion of THBD is present as a soluble form in plasma. We report the case of a 19‐yr‐old man with aHUS secondary to a THBD mutation that relapsed twice after two renal transplantations performed 12 yr apart. Despite successful control of HUS with plasma exchange and eculizumab after the second transplantation, the graft was ultimately lost due to severe steroid‐resistant cellular rejection. The present report suggests that THBD mutations may favor‐relapse of aHUS after renal transplantation.     

Recent advances in the understanding of transient abnormal myelopoiesis in Down syndrome

Neonates with Down syndrome (DS) have a propensity to develop the unique myeloproliferative disorder, transient abnormal myelopoiesis (TAM). TAM usually resolves spontaneously in ≤3 months, but approximately 10% of patients with TAM die from hepatic or multi‐organ failure. After remission, 20% of patients with TAM develop acute myeloid leukemia associated with Down syndrome (ML‐DS). Blasts in both TAM and ML‐DS have trisomy 21 and GATA binding protein 1 (GATA1) mutations. Recent studies have shown that infants with DS and no clinical signs of TAM or increases in peripheral blood blasts can have minor clones carrying GATA1 mutations, referred to as silent TAM. Low‐dose cytarabine can improve the outcomes of patients with TAM and high white blood cell count. A number of studies using fetal liver cells, mouse models, or induced pluripotent stem cells have elucidated the roles of trisomy 21 and GATA1 mutations in the development of TAM. Next‐generation sequencing of TAM and ML‐DS patient samples identified additional mutations in genes involved in epigenetic regulation. Xenograft models of TAM demonstrate the genetic heterogeneity of TAM blasts and mimic the process of clonal selection and expansion of TAM clones that leads to ML‐DS. DNA methylation analysis suggests that epigenetic dysregulation may be involved in the progression from TAM to ML‐DS. Unraveling the mechanisms underlying leukemogenesis and identification of factors that predict progression to leukemia could assist in development of strategies to prevent progression to ML‐DS. Investigation of TAM, a unique pre‐leukemic condition, will continue to strongly influence basic and clinical research into the development of hematological malignancies.     

Prenatal diagnosis of Gaucher disease using next‐generation sequencing

In the prenatal diagnosis of Gaucher disease (GD), glucocerebrosidase (GBA) activity is measured with fetal cells, and gene analysis is performed when pathogenic mutations in GBA are identified in advance. Herein is described prenatal diagnosis in a family in which two children had GD. Although prior genetic information for this GD family was not obtained, next‐generation sequencing (NGS) was carried out for this family because immediate prenatal diagnosis was necessary. Three mutations were identified in this GD family. The father had one mutation in intron 3 (IVS2 + 1), the mother had two mutations in exons 3 (I[‐20]V) and 5 (M85T), and child 1 had all three of these mutations; child 3 had none of these mutations. On NGS the present fetus (child 3) was not a carrier of GD‐related mutations. NGS may facilitate early detection and treatment before disease onset.     

Incidence,risk factors,and outcome of blood stream infections during the first 100 days post‐pediatric allogeneic and autologous hematopoietic stem cell transplantations

Bloodstream infections (BSI) are a frequently observed complication after hematopoietic stem cell transplant (HSCT). Retrospective analysis of clinical and microbiological data during the first 100 days from 302 consecutive pediatric patients who underwent HSCT for a malignant disease at our institute between January 2013 and June 2017. A total of 164 patients underwent autologous and 138 allogeneic HSCT. The overall incidence of BSI was 37% with 92% of infectious episodes occurring during the pre‐engraftment phase. Gram‐positive bacteria (GPB) accounted for 54.6% of the isolated pathogens, gram‐negative bacteria (GNB) for 43.9%, and fungi for 1.4%. Coagulase‐negative staphylococci and Escherichia coli were the most commonly isolated GPB and GNB, respectively. Forty‐five percent of GNB were extended‐spectrum beta‐lactamase producers and 21% were multidrug‐resistant organisms. Fluoroquinolone resistance was 92% and 68%, among GPB and GNB, respectively. Risk factors for BSI in univariate analysis were allogeneic HSCT, delayed time to engraftment more than 12 days, previous BSI before HSCT, and alternative donor. In multivariate analysis, only HSCT type (allogeneic vs autologous P = .03) and previous BSI within 6 months before HSCT (P = .016) were significant. Overall survival at day 100 was 98% and did not differ significantly between patients with and without BSI (P = .76). BSI is common in children undergoing HSCT for malignant diseases. Allogeneic HSCT recipients and previous BSI within 6 months before HSCT are associated with increased risk of post‐transplant BSI. With current supportive measures, BSI does not seem to confer an increased risk for 100‐day mortality.     

Frequency of asymptomatic and symptomatic respiratory virus detection in pediatric hematopoietic cell transplant patients

Respiratory viral infections are common and can cause significant morbidity and mortality in pediatric patients undergoing hematopoietic cell transplantation (HCT). The prevalence of disease has been primarily identified from retrospective studies using standard‐of‐care specimens. The incidence of both asymptomatic respiratory viral detection and symptomatic respiratory viral detection in this high‐risk population is not well described. We performed longitudinal, active, prospective surveillance in pediatric HCT patients. Subjects underwent weekly midturbinate swabs (MTSs) for the detection of 18 respiratory viruses and subtypes peri‐HCT and 100 days post‐HCT. Clinical data were obtained from the medical record. From September 2015 to February 2017, 24 children underwent 29 HCT, and 284 MTSs were collected. Forty‐two (15%) specimens were virus‐positive from 10 (42%) subjects. Specimens from children undergoing allogeneic HCT were more likely to have a virus detected (17% vs 8%, P = .04) compared with specimens from children undergoing autologous HCT. Sixteen (38%) detections were not associated with symptoms. Almost half (8/17) of the unique viral infections occurred during the HCT hospitalization after a negative specimen, suggesting nosocomial acquisition, and preceded detection from a clinical specimen. Rhinovirus, the most common virus detected, was the only virus detected in 33 (81%) virus‐positive specimens; only 11 (33%) rhinovirus detections were asymptomatic. Asymptomatic detection of coronavirus and bocavirus occurred. Asymptomatic respiratory virus detection occurred in more than one‐third of the children undergoing HCT. The acquisition of respiratory viruses during HCT hospitalization suggests nosocomial acquisition. Early detection of respiratory viruses during asymptomatic periods could have infection prevention and treatment implications.     

Osteopetrosis mimicking juvenile myelomonocytic leukemia

A 5‐month‐old boy developed splenomegaly, anemia, thrombocytopenia with elevated white cells, monocytosis and immature granulocytes in the peripheral blood. Bone marrow showed dysplasia without blastosis. Increased colony‐forming unit‐granulocyte–macrophage was found in the peripheral blood, mimicking granulocyte–macrophage colony‐stimulating factor hypersensitivity. These findings fulfilled the diagnosis criteria for juvenile myelomonocytic leukemia (JMML), but no mutations in the CBL, NRAS, KRAS, or PTPN11 genes were detected. In addition to these findings severe hypogammaglobulinemia and elevated alkaline phosphatase were present. Bone X‐ray showed dense and radiopaque bones with a bone‐in‐bone appearance characteristic of infantile malignant osteopetrosis (IMO). Genetic mutation in T‐cell, immune regulator 1 (TCIRG1) was identified, confirming the diagnosis of IMO. Careful differential diagnosis including osteopetrosis, is therefore recommended in patients with clinical features and hematologic findings consistent with JMML.     

Outcome of autologous hematopoietic stem cell transplantation in children and adolescents with relapsed or refractory Hodgkin's lymphoma

This study evaluates the outcome of 66 pediatric patients with rrHL who underwent autoHSCT. Twenty‐nine patients experienced early relapse, and 19 patients experienced late relapse. Of 18 newly diagnosed with HL, 13 were primary refractory disease and five had late responsive disease. At the time of transplantation, only 68% of the patients were chemosensitive. The majority of patients received BCNU + etoposide + ara‐C + melphalan for conditioning (45/66), and peripheral blood (56/66) was used as a source of stem cells. After a median follow‐up period of 39 months, 46 patients were alive. At five yr, the probabilities of OS, EFS, the relapse rate, and the non‐relapse mortality rate were 63.1%, 54.3%, 36.4%, and 9.1%, respectively. The probability of EFS in chemosensitive and chemoresistant patients at five yr was 72.3% and 19%, respectively (p < 0.001). Multivariate analysis showed that chemoresistant disease at the time of transplantation was the only factor predicting limited both OS (hazard ratio = 4.073) and EFS (hazard ratio = 4.599). AutoHSCT plays an important role for the treatment of rrHL in children and adolescents, and survival rates are better for patients with chemosensitive disease at the time of transplantation.     

Control of graft‐versus‐host disease with rabbit anti‐thymocyte globulin,rituximab, and bortezomib in TCRαβ/CD19‐depleted graft transplantation for leukemia in children: a single‐center retrospective analysis of two GVHD‐prophylaxis regimens

Both acute GVHD and chronic GVHD remain the leading cause of morbidity and death after allogeneic HSCT. We conducted a retrospective analysis comparing two GVHD‐prophylaxis regimens: 35 patients received “Regimen 1” (horse ATG, tacrolimus, and methotrexate) and 46 “Regimen 2” (rabbit ATG, rituximab, and peritransplant bortezomib). All 81 patients with a median age of 9 (0.6‐23) years with ALL (n = 31) or AML (n = 50) in complete remission received TCRαβ/CD19‐depleted transplants between May 2012 and October 2016, from 40 HLA‐matched unrelated and 41 haploidentical donors. After a median follow‐up of 3.9 years, the CI of acute GVHD II‐IV was 15% (95% CI: 7‐30) in the “Regimen 2” group and 34% (95% CI: ?54) in the “Regimen 1” group, P = .05. “Regimen 2” was also more effective in the prevention of chronic GVHD; the CI at 1 year after HSCT was 7% (95% CI: 2‐19) vs 31% (95% CI: 19‐51), P = .005. The CI of relapse at 3 years adjusted for the GVHD‐prophylaxis regimen groups 31% (95% CI: 19‐51) for the “Regimen 1” vs 21% (95% CI: 11‐37) for the “Regimen 2”, P = .3. The retrospective observation suggests that the use of the rATG, rituximab, and bortezomib was associated with significantly lower rate of GVHD without the loss of anti‐leukemic activity.     

Ifosfamide,gemcitabine, and vinorelbine is an effective salvage regimen with excellent stem cell mobilization in relapsed or refractory pediatric Hodgkin lymphoma

We describe 12 pediatric patients (8‐16 years) with primary refractory (N = 6) or first relapse (N = 6) Hodgkin lymphoma (HL) treated with ifosfamide, gemcitabine, and vinorelbine (IGEV). The overall response rate to IGEV was 100%, with seven (58%) complete responses (CR) and five (42%) partial responses. Successful CD34⁺ stem cell mobilization was achieved in all patients. Following subsequent autologous stem cell transplantation, 10 patients (83%) achieved CR. At a median follow‐up of 71 months, 11 patients had no evidence of disease. Five‐year second event‐free survival and overall survival were 83% ± 11.0% and 90.0% ± 9.5%, respectively. IGEV is an effective salvage regimen for children with relapsed/refractory HL.