We report a retrospective single-center analysis of pediatric patients with relapsed or refractory B-cell precursor acute lymphoblastic leukemia focusing on relapses outside of the typical locations, bone marrow, central nervous system, or testes. The purpose of the analysis was to describe the relapse patterns after immunotherapy with the bispecific antibody blinatumomab. The cohort includes 90 patients suffering a total of 167 relapses. The majority of relapses, 103/167 (61.7%), were isolated bone marrow relapses, while 34/167 (20.4%) were combined bone marrow and extramedullary relapses (EMR), and 30/167 (18.0%) were classified as isolated extramedullary relapses (IEMR). EMR included 36/64 (56.3%) central nervous system relapses, 10/64 (15.6%) testicular relapses, and 18/64 (28.1%) relapses occurred in other extramedullary sites (OEMR). Seven in 64 (4.2%) of these OEMR presented as isolated OEMR without bone marrow involvement at the time of diagnosis. Multivariate analyses did not show significant differences in EMR rates for patients undergoing hematopoietic stem cell transplantation, patients receiving total body irradiation or patients suffering acute or chronic graft-versus-host disease. Blinatumomab treatment, however, displayed a significant association with OEMR (HR 3.169; 95% CI [1.032-9.728], p = 0.044) and an increased risk for isolated OEMR (HR 13.322; 95% CI [2.276-77.989], p = 0.004) in univariate and multivariate analyses. These results suggest a higher rate of OEMR after treatment with blinatumomab in pediatric ALL, and require confirmation by prospective trials as well as consented diagnostic and therapeutic algorithms.

The etiology of pediatric acute lymphatic leukemia (ALL) is still unclear. Whole-metagenome shotgun sequencing of bone marrow samples in patients with treatment-naïve ALL (n=6) was performed for untargeted investigation of bacterial and viral DNA. The control group consisted of healthy children (n=4) and children with non-oncologic diseases (n=2) undergoing bone marrow sampling. Peripheral blood of all participants was investigated at the same time. After bioinformatical elimination of potential contaminants by comparison with the employed controls, no significant amounts of microbial or viral DNA were identified.

PURPOSE Patients with relapsed high-risk neuroblastoma (rHR-NB) have a poor prognosis. We hypothesized that graft-versus-neuroblastoma effects could be elicited by transplantation of haploidentical stem cells (haplo-SCT) exploiting cytotoxic functions of natural killer cells and their activation by the anti-GD2 antibody dinutuximab beta (DB). This phase I/II trial assessed safety, feasibility, and outcomes of immunotherapy with DB plus subcutaneous interleukin-2 (scIL2) after haplo-SCT in patients with rHR-NB. METHODS Patients age 1-21 years underwent T-/B-cell–depleted haplo-SCT followed by DB and scIL2. The primary end point ‘success of treatment’ encompassed patients receiving six cycles, being alive 180 days after end of trial treatment without progressive disease, unacceptable toxicity, acute graft-versus-host-disease (GvHD) ≥grade 3, or extensive chronic GvHD. RESULTS Seventy patients were screened, and 68 were eligible for immunotherapy. Median number of DB cycles was 6 (range, 1-9). Median number of scIL2 cycles was 3 (1−6). The primary end point was met by 37 patients (54.4%). Median observation time was 7.8 years. Five-year event-free survival (EFS) and overall survival from start of trial treatment were 43% (95% CI, 31 to 55) and 53% (95% CI, 41 to 65), respectively. Five-year EFS among patients in complete remission (CR; 52%; 95% CI, 31 to 69) or partial remission (44%; 95% CI, 27 to 60) before immunotherapy were significantly better compared with patients with nonresponse/mixed response/progressive disease (13%; 95% CI, 1 to 42; P = .026). Overall response rate in 43 patients with evidence of disease after haplo-SCT was 51% (22 patients), with 15 achieving CR (35%). Two patients developed GvHD grade 2 and 3 each. No unexpected adverse events occurred. CONCLUSION DB therapy after haplo-SCT in patients with rHR-NB is feasible, with low risk of inducing GvHD, and results in long-term remissions likely attributable to increased antineuroblastoma activity by donor-derived effector cells.

BackgroundA lower baseline bone marrow blast percentage (bBMB%) is associated with better outcomes in patients with B-cell acute lymphoblastic leukemia (B-ALL) receiving blinatumomab. The objective of this analysis was to investigate the association between bBMB% and treatment outcomes in relapsed/refractory (R/R) B-ALL. MethodsData from five trials of blinatumomab for R/R B-ALL were pooled for analyses. Patients were placed in one of three groups: group 1, >= 50% bBMBs; group 2, >= 25% to <50% bBMBs; group 3, >= 5% to Data from 683 patients (166 pediatric, 517 adult) were analyzed. Collectively, patients in groups 2 and 3 had significantly higher odds of achieving a complete remission (CR) (odds ratio [OR], 3.50 [95% confidence interval (CI), 2.23-5.48] and 3.93 [95% CI, 2.50-6.18], respectively; p < .001) and minimal/measurable residual disease response (OR, 2.61 and 3.37, respectively; p < .001) when compared with group 1 (reference). Groups 2 and 3 had a 37% and 46% reduction in the risk of death (hazard ratio [HR], 0.63 and 0.54, respectively; p < .001) and a 41% and 43% reduction in the risk of an event (relapse or death) (HR, 0.59 and 0.57, respectively; p < .001) compared with group 1. No significant differences in response or survival outcomes were observed between groups 2 and 3. Seven of nine patients whose bBMB% was lowered to <50% with dexamethasone achieved CR with blinatumomab. ConclusionAny bBMB% <50% was associated with improved efficacy following blinatumomab treatment for R/R B-ALL.

Immune milieus play an important role in various types of cancer. The present study focuses on the effect of Th1 cytokines on pediatric acute lymphoblastic leukemia (ALL). The reaction of ALL cell lines and patient-derived xenografts (PDX) to the most important Th1 cytokines TNF-α (tumor necrosis factor alpha) and IFN-γ (interferon gamma) is analyzed and correlated with the respective cytokine receptors and the intracellular signaling molecules. ALL cell lines and ALL PDX display a great heterogeneity in cell death after incubation with TNF-α and IFN-γ. Several samples show a dose-dependent and additive induction of cell death by both cytokines; others do not react at all or even display an increased viability. Apoptosis is the main type of cell death induced by Th1 cytokines in ALL cells. Over all leukemia cells analyzed, IFN-γ receptor (IFNGR) shows a higher expression than both TNF-receptors, resulting in higher phosphorylation of STAT1 (signal transducer and activator of transcription) compared to phosphorylation of NF-κB (nuclear factor kappa-light-chain-enhancer of activated B-cells) in the TNF pathway. The activation of STAT1 correlates with the amount of cell death after stimulation with Th1 cytokines. TNF-α and IFN-γ lead to heterogeneous reactions in ALL cell lines and ALL PDX but are able to induce cell death by apoptosis in the majority of ALL blasts. The correlation of a high expression of IFNGR and following activation of STAT1 with cell death indicates an important role for IFN-γ signaling in this setting.

Purpose Despite excellent long-term overall survival rates, pediatric low-grade gliomas (pLGG) show high variety of clinical behavior regarding progress or senescence post incomplete resection (IR). This study retrospectively analyzes tumor growth velocity (TGV) of pLGG before surgery and after IR to investigate the impact of surgical extent, tumor location and molecular BRAF status on postoperative residual tumor growth behavior. Methods Of a total of 172 patients with pLGG receiving surgical treatment, 107 underwent IR (66%). Fifty-three vs 94 patients could be included in the pre- and post-operative cohort, respectively, and were observed over a mean follow-up time of 40.2 vs 60.1 months. Sequential three-dimensional MRI-based tumor volumetry of a total of 407 MRI scans was performed to calculate pre- and postoperative TGV. Results Mean preoperative TGV of 0.264 cm 3 /month showed significant deceleration of tumor growth to 0.085 cm 3 /month, 0.024 cm 3 /month and −0.016 cm 3 /month after 1st, 2nd, and 3rd IR, respectively (p < 0.001). Results remained significant after excluding patients undergoing (neo)adjuvant treatment. Resection extent showed correlation with postoperative reduction of TGV (R = 0.97, p < 0.001). ROC analysis identified a residual cut-off tumor volume > 2.03 cm 3 associated with a higher risk of progress post IR (sensitivity 78,6%, specificity 76.3%, AUC 0.88). Postoperative TGV of BRAF V600E-mutant LGG was significantly higher than of BRAF wild-type LGG (0.123 cm 3 /month vs. 0.016 cm 3 /month, p = 0.047). Conclusion This data suggests that extensive surgical resection may impact pediatric LGG growth kinetics post incomplete resection by inducing a significant deceleration of tumor growth. BRAF-V600E mutation may be a risk factor for higher postoperative TGV.

Background: Leukemia in children has a good prognosis with an overall cure rate of 85% in pediatric patients with acute lymphoblastic leukemia and 50-60% in pediatric patients with acute myeloid leukemia.Nevertheless in patients with refractory or relapsed leukemia the prognosis is limited and can only be cured by a salvage chemotherapy, in most cases followed by an allogeneic hematopoietic stem cell transplantation.Methods: In this retrospective case cohort ananlysis we investigated the outcome of eight patients with relapsed or refractory acute myeloid (n=2), lymphoblastic (n=4), biphenotypic (n=1) leukemia or T-lymphoblastic lymphoma (n=1) who failed to respond to standard salvage regimens.They received a salvage therapy with melphalan and cytarabine at our institution between 2015 and 2019.Results: After salvage chemotherapy with melphalan and cytarabine 63% of the patients achieved a remission of the disease and qualified for subsequent allogeneic hematopoietic stem cell transplantation.The one year overall survival rate was 50%, the three year overall survival rate was 29%.25% of patients experienced a temporary period of fever and SIRS.Conclusions: The reported results of our case cohort analysis indicate that a salvage therapy with melphalan and cytarabine in relapsed or refractory leukemia could represent a curative approach with the possibility of achieving remission and subsequent allogeneic hematopoietic stem cell transplantation.Future multicentre studies are needed to verify the here presented results.

Background Neuroblastoma (NB) is the most common paediatric extracranial solid malignancy. We analysed the role of the epitope detection in monocytes (EDIM) technique for liquid biopsy in NB patients. Methods Tumour epitopes transketolase-like 1 (TKTL1), Apo10 (DNaseX) and GD2 were assessed: expression levels in seven NB tumour samples and five NB cell lines were analysed using RT-PCR and flow cytometry. LAN-1 cells were co-cultured with blood and assessed using EDIM. Peripheral blood macrophages of patients with neuroblastoma (n = 38) and healthy individuals (control group, n = 37) were labelled (CD14(+)/CD16(+)) and assessed for TKTL1, Apo10 and GD2 using the EDIM technology. Results mRNA expression of TKTL1 and DNaseX/Apo10 was elevated in 6/7 NB samples. Spike experiments showed upregulation of TKTL1, Apo10 and GD2 in LAN-1 cells following co-culturing with blood. TKTL1 and Apo10 were present in macrophages of 36/38 patients, and GD2 in 15/19 patients. The 37 control samples were all negative. EDIM expression scores of the three epitopes allowed differentiation between NB patients and healthy individuals. Conclusions The EDIM test might serve as a non-invasive tool for liquid biopsy in children suffering from NB. Future studies are necessary for assessing risk stratification, tumour biology, treatment monitoring, and early detection of tumour relapses.

Allogeneic stem cell transplantation is currently the only curative approach for a variety of malignant and non-malignant diseases. In the early transplant era, the intent of this treatment was to apply an intensive myeloablative regimen to eliminate residual malignant cells followed by the hematopoietic rescue of the patients with donor hematopoietic stem cells. However, the focus has shifted over time and allogeneic transplantation is nowadays seen as a cellular therapy in which the donor-derived immune system mounts an anti-infectious and especially an anti-tumor effect in the posttransplant phase. In order to further augment the anti-tumor effect, various approaches have been developed, including the manipulation of the donor-derived immune system in vivo or the adoptive transfer of ex vivo-expanded donor-derived effector cells. Based on their lack of alloreactivity, γδ+ T cells are shifting into the spotlight of research in the context of allogeneic transplantation. Their exploitation with regard to their anti-infectious and anti-tumor properties and their in vivo and ex vivo manipulation will lead to new therapeutic approaches to improve the outcome of patients after allogeneic stem cell transplantation. In this review, the important role of γδ+ T cells in allogeneic matched and mismatched transplantation is summarized and an outlook is discussed on how to best make use of this unique cell population.

In addition to surgical management, corticosteroids have proven to be beneficial in the management of acute symptoms related to CNS tumors, and have been widely used for many decades, with dexamethasone (DM) representing the most commonly used agent. However, lately published in vitro data possibly indicates a DM‐induced suppression of oncogene‐induced senescence (OIS) in a preclinical pediatric low‐grade glioma (pLGG) model, which, alongside data associating perioperative DM treatment with reduced event‐free survival in adult glioma, raises questions concerning the safety of DM treatment in pLGG. A total of 172 patients with pLGG were retrospectively analyzed concerning the impact of perioperative DM application on postoperative short‐ and long‐term tumor growth velocity and progression‐free survival (PFS). Three‐dimensional volumetric analyses of sequential MRI follow‐up examinations were used for assessment of tumor growth behavior. Mean follow‐up period accounted for 60.1 months. Sixty‐five patients (45%) were perioperatively treated with DM in commonly used doses. Five‐year PFS accounted for 93% following gross‐total resection (GTR) and 57% post incomplete resection (IR). Comparison of short‐ and long‐term postoperative tumor growth rates in patients with vs without perioperative DM application showed no significant difference (short‐term: 0.022 vs 0.023 cm3/month, respectively; long‐term: 0.019 vs 0.023 cm3/month, respectively). Comparison of PFS post IR (5‐year‐PFS: 65% vs 55%, respectively; 10‐year‐PFS: 52% vs 53%, respectively) and GTR (5‐ and 10‐years‐PFS: 91% vs 92%, respectively) likewise showed similarity. This data emphasizes the safety of perioperative DM application in pLGG, adding further evidence for decision making and requested future guidelines.

Arsenic trioxide (ATO) has become an established component of treatment protocols for acute promyelocytic leukemia (APL) with excellent efficacy and no relevant sustained toxicity. Part of its action has been attributed to the inhibition of Hedgehog signaling (Hh) which enables a possible therapeutic approach as many pediatric tumor entities have been associated with increased Hh activity. We retrospectively analyzed 31 patients with refractory and relapsed pediatric cancer who were treated with ATO at the University Children's Hospital of Tuebingen. Additionally a literature review on the clinical and preclinical use of ATO in pediatric cancer treatment was performed.ATO alone as well as combinations with other drugs have proven effective in vitro and in mouse models of various pediatric malignancies. However, only few data on the clinical use of ATO in pediatric patients besides APL exist. In our patient sample, ATO was overall well tolerated in the treatment of various pediatric cancers, even in combination with other cytostatic drugs. Due to distinct tumor entities, differently progressed disease stages and varying co-medication, no clear statement can be made regarding the efficacy of ATO treatment. However, patients with proven Hh activation in molecular tumor profiling surpassed all other patients, who received ATO in an experimental treatment setting, in terms of survival. As molecular profiling of tumors increases and enhanced Hh activity can be detected at an early stage, ATO might expand its clinical use to other pediatric malignancies beyond APL depending on further clinical studies.

In recent decades, antibody-dependent cellular cytotoxicity (ADCC)-inducing monoclonal antibodies (mAbs) have revolutionized cancer immunotherapy, and Fc engineering strategies have been utilized to further improve efficacy. A promising option is to enhance the affinity of an antibody's Fc-part to the Fc-receptor CD16 by altering the amino acid sequence. Herein, we characterized an S239D/I332E-modified CD133 mAb termed 293C3-SDIE for treatment of B cell acute lymphoblastic leukemia (B-ALL). Flow cytometric analysis revealed CD133 expression on B-ALL cell lines and leukemic cells of 50% (14 of 28) B-ALL patients. 293C3-SDIE potently induced NK cell reactivity against the B-ALL cell lines SEM and RS4;11, as well as leukemic cells of B-ALL patients in a target antigen-dependent manner, as revealed by analysis of NK cell activation, degranulation, and cytotoxicity. Of note, CD133 expression did not correlate with BCR-ABL, CD19, CD20, or CD22, which are presently used as therapeutic targets in B-ALL, which revealed CD133 as an independent target for B-ALL treatment. Increased CD133 expression was also observed in MLL-AF4-rearranged B-ALL, indicating that 293C3-SDIE may constitute a particularly suitable treatment option in this hard-to-treat subpopulation. Taken together, our results identify 293C3-SDIE as a promising therapeutic agent for the treatment of B-ALL.

Primary immunodeficiencies (PIDs) are inherited disorders of the immune system with allogeneic hematopoietic stem cell transplantation (HSCT) as the only curative treatment in some of them. In case an HLA-matched donor is not available, HSCT from a haploidentical family donor may be considered. We compared the outcomes of HSCT from HLA-matched unrelated or related donors (MUDs or MRDs) and mismatched related haploidentical donors (MMRDs) in patients with a variety of PIDs in 2 centers. A total of 44 pediatric patients were evaluated. We reviewed the outcomes of 25 children who underwent transplantation with HLA-matched grafts (MRD, n = 13; MUD, n = 12) and 19 patients receiving haploidentical stem cells. Bone marrow (BM) was transplanted in 85% (MRD) and 75% (MUD) of the matched cohort and peripheral blood stem cells (PBSCs) in 15% (MRD), 25% (MUD), and 100% (MMRD). All but 9 patients (MRD, n = 6; MMRD, n = 3) with severe combined immunodeficiency (SCID) received a chemotherapy-based conditioning regimen. Immune reconstitution of T, B, and natural killer cells was comparable for all groups with an advantage of recipients of MRD grafts in early CD4 reconstitution. However, deaths due to viral infections occurred more often in the haploidentical cohort. The disease-free survival was 91.7% (MRD), 66.7% (MUD), and 62.7% (MMRD), respectively. Grade II to IV acute graft-versus-host disease (GVHD) occurred in 15% (MRD), 8% (MUD), and 21% (MMRD) of the patients. Only 1 patient had severe grade IV GVHD in the MRD group, whereas no grade >II GVHD was observed in the MUD or MMRD cohort. These data indicate that in the absence of a suitable HLA-identical family donor, haploidentical HSCT may be a viable option for patients with life-threatening disease and urgent need of HSCT. (C) 2020 The American Society for Transplantation and Cellular Therapy. Published by Elsevier Inc. All rights reserved.