Predictive factors for radiation-induced pituitary damage in pediatric patients with brain tumors

BACKGROUND AND PURPOSE

Multiple studies demonstrated hypothalamic-pituitary dysfunction in survivors of pediatric brain tumors. However, few studies investigated the trajectories of pituitary height in these patients and their associations with pituitary function. We aimed to evaluate longitudinal changes of pituitary height in children and adolescents with brain tumors, and their association with endocrine deficiencies.

MATERIALS AND METHODS

We conducted a retrospective analysis of 193 pediatric patients (54.9% male) diagnosed with brain tumors from 2002 to 2018, with a minimum of two years of radiological follow-up. Pituitary height was measured using MRI scans at diagnosis and at 2, 5, and 10 years post-diagnosis, with clinical data sourced from patient charts.

RESULTS

Average age at diagnosis was 7.6 ± 4.5 years, with a follow-up of 6.1 ± 3.4 years. 52.8% underwent radiotherapy and 37.8% experienced pituitary hormone deficiency. Radiation treatment was a significant predictor of decreased pituitary height at all observed time points (p = 0.016, p < 0.001, p = 0.008, respectively). Additionally, chemotherapy (p = 0.004) or radiotherapy (p = 0.022) history and pituitary height at 10 years (p = 0.047) were predictors of endocrine deficiencies. ANOVA revealed an expected increase in pituitary height over time in pediatric patients, but this growth was significantly impacted by radiation treatment and gender (p for interaction = 0.005 and 0.025, respectively).

CONCLUSION

Cranial irradiation in pediatric patients is associated with impairment of the physiologic increase in pituitary size; in turn, decreased pituitary height is associated with endocrine dysfunction. We suggest that pituitary gland should be evaluated on surveillance imaging of pediatric brain tumor survivors, and if small for age, clinical endocrine evaluation should be pursued.

Neoadjuvant BRAF-targeted therapy for ameloblastoma of the mandible: an organ preservation approach

BACKGROUND

Ameloblastoma is a rare odontogenic neoplasm frequently located in the mandible. Standard treatment involves radical bone resection and immediate reconstruction, causing functional, aesthetic, and psychological impairments. The BRAF V600E mutation is present in approximately 80% of mandible ameloblastomas, and BRAF inhibitors have demonstrated sustained responses in unresectable cases.

METHODS

We identified ameloblastoma patients planned for ablative surgery and screened them for BRAF V600E mutation. Neoadjuvant BRAF inhibitors were offered to facilitate jaw preservation surgery. Retrospective data collection encompassed treatment regimens, tolerability, tumor response, and conversion to mandible preservation surgery.

RESULTS

Between 2017 and 2022, a total of 11 patients received dabrafenib (n = 6) or dabrafenib with trametinib (n = 5). The median age was 19 (range = 10-83) years. Median treatment duration was 10 (range = 3-20) months. All (100%) patients achieved a radiological response. Ten (91%) patients successfully converted to mandible preservation surgery with residual tumor enucleation. One patient attained complete radiological response, and surgery was not performed. Among the 10 surgically treated patients, all exhibited a pathological response, with 4 achieving near complete response and 6 partial response. At a median follow-up of 14 (range = 7-37) months after surgery, 1 case of recurrence was observed. Grade 1-2 adverse effects were reported in 8 (73%) patients, with a single case of grade 3 (hepatitis). Dose modification was necessary for 3 patients, and 4 experienced treatment interruptions, while 1 patient permanently discontinued therapy.

CONCLUSIONS

Neoadjuvant BRAF inhibition may offer a safe and effective strategy for organ preservation in mandible ameloblastoma treatment.

Cerebral Spinal Fluid Parameters Following CD19-Targeted Therapies in Children and Young Adults

The presence of leukocytes in the cerebral spinal fluid (CSF) of patients with acute lymphoblastic leukemia may indicate a relapse in the central nervous system. CD19-directed immunotherapy may increase the blood-brain barrier permeability, leading to neurologic toxicity and infiltrate the CNS. We studied the CSF cell and protein content in 71 consecutive patients who received either CD19 chimeric antigen receptor T cells or blinatumomab. Responding patients had an incidence of 66% and 61% of pleocytosis following blinatumomab or chimeric antigen receptor T cells, respectively. CSF parameters did not correlate with toxicity or prior CNS disease. Routine CSF flow cytometry following immunotherapy to distinguish T-cell infiltration from CNS relapse should be considered.

Improved Outcome Following Busulfan-Based Conditioning in Children with Functional Neutrophil Disorders Undergoing Hematopoietic Stem Cell Transplant from HLA-Matched Donors

Hematopoietic stem-cell transplantation (HSCT) is the only curative treatment for chronic granulomatous disease (CGD) and leukocyte-adhesion deficiency (LAD), but both diseases have high rates of graft failure in transplant and patients with these diseases are often referred to HSCT with significant comorbidity. The intensity of the conditioning regimen should be balanced between the need to ensure durable engraftment and to minimize toxicity when transplanting young children with infections and organ damage. We report on 26 children transplanted at our institution with CGD and LAD over 24 years. We found a higher incidence of graft failure in patients receiving treosulfan based conditioning for their first transplant. There was no effect of conditioning regimen on overall survival, as all 8 patients that proceeded to a second busulfan-based HSCT were salvaged. We recommend giving patients with CGD and LAD fully myeloablative conditioning with either a busulfan-based regimen or the combination of treosulfan, fludarabine, and thiotepa.

Improved CAR-T cell activity associated with increased mitochondrial function primed by galactose

CD19 CAR-T cells have led to durable remissions in patients with refractory B-cell malignancies; nevertheless, most patients eventually relapse in the long term. Many interventions aimed at improving current products have been reported, with a subset of them focusing on a direct or indirect link to the metabolic state of the CAR-T cells. We assessed clinical products from an ongoing clinical trial utilizing CD19-28z CAR-T cells from patients with acute lymphoblastic leukemia. CAR-T clinical products leading to a complete response had significantly higher mitochondrial function (by oxygen consumption rate) irrespective of mitochondrial content. Next, we replaced the carbon source of the media from glucose to galactose to impact cellular metabolism. Galactose-containing media increased mitochondrial activity in CAR-T cells, and improved in vitro efficacy, without any consistent phenotypic change in memory profile. Finally, CAR-T cells produced in galactose-based glucose-free media resulted in increased mitochondrial activity. Using an in vivo model of Nalm6 injected mice, galactose-primed CAR-T cells significantly improved leukemia-free survival compared to standard glucose-cultured CAR-T cells. Our results prove the significance of mitochondrial metabolism on CAR-T cell efficacy and suggest a translational pathway to improve clinical products.

Hypothalamic-pituitary-gonadal function, pubertal development, and fertility outcomes in male and female medulloblastoma survivors: a single-center experience

BACKGROUND

Endocrine deficiencies, including hypothalamic-pituitary-gonadal axis (HPGA) impairment, are common in survivors of childhood and adolescent medulloblastoma. Still, data regarding pubertal development and fecundity are limited, and few studies assessed HPGA function in males. We aimed to describe HPGA function in a large cohort of patients with medulloblastoma.

METHODS

A retrospective study comprising all 62 medulloblastoma patients treated in our center between 1987 and 2021, who were at least 2 years from completion of therapy. HPGA function was assessed based on clinical data, biochemical markers, and questionnaires.

RESULTS

Overall, 76% of female patients had clinical or biochemical evidence of HPGA dysfunction. Biochemical evidence of diminished ovarian reserve was seen in all prepubertal girls (n = 4). Among the males, 34% had clinical or biochemical evidence of gonadal dysfunction, 34% had normal function, and 29% were age-appropriately clinically and biochemically prepubertal. The difference between males and females was significant (P = .003). Cyclophosphamide-equivalent dose was significantly associated with HPGA function in females, but not in males. There was no association between HPGA dysfunction and other endocrine deficiencies, length of follow-up, weight status, and radiation treatment protocol. Two female and 2 male patients achieved successful pregnancies, resulting in 6 live births.

CONCLUSIONS

HPGA dysfunction is common after treatment for childhood medulloblastoma. This is seen more in females, likely due to damage to the ovaries from spinal radiotherapy. Our findings may assist in counseling patients and their families regarding risk to future fertility and need for fertility preservation.

αβ+ /CD19+ -depleted haploidentical stem cell transplantation for children with acute leukemia: Is there a protective effect of increased γδ+ T-cell content in the graft?

BACKGROUND

Haploidentical hematopoietic stem cell transplantation (HSCT) with depletion of αβ⁺ T cells and CD19⁺ B cells has emerged as a viable alternative to traditional donors for treating acute leukemia in children. As the use of this innovative approach continues to grow and more experience is gained, it is essential to identify and comprehend the key factors that contribute to successful transplantation and improved outcomes.

METHODS

We conducted a retrospective analysis of single-center data from 27 children with acute lymphoblastic leukemia and 11 children with acute myeloid leukemia who underwent haploidentical HSCT with depletion of αβ⁺ T cells and CD19⁺ B cells between the years 2013 and 2020.

RESULTS

Engraftment was successful in 35 out of 38 patients (92%), who were all children conditioned using either a total body irradiation-based regimen or a treosulfan, fludarabine, and thiotepa regimen engrafted successfully. The 5-year overall survival and event-free survival rates were 51% and 42%, respectively. There were no cases of grade III-IV acute graft-versus-host disease, and only two patients developed chronic graft-versus-host disease. Patients with a higher content of γδ⁺ T cells in the graft demonstrated a longer event-free survival.

CONCLUSIONS

αβ⁺ /CD19⁺ -depleted haploidentical hematopoietic stem cell transplantation can offer long-term remission for children with acute leukemia with minimal graft-versus-host disease.

[CAR-T CELL THERAPY FOR B-CELL ACUTE LYMPHOBLASTIC LEUKEMIA WITH A LARGE OVARIAN EXTRAMEDULLARY MASS]

INTRODUCTION

Acute lymphoblastic leukemia (ALL) is the most common malignancy in childhood, arising from the bone marrow. ALL may present at diagnosis or relapse at extramedullary sites. In recent years, autologous T-cells engineered to express a chimeric-antigen receptor (CAR-T cells) have emerged as novel immune-based therapies for relapsed and refractory ALL, targeting the B-cell surface antigen CD19. Here we present a patient with relapsed ALL involving the ovaries, treated with CD19 CAR-T cells. Toxicity included cytokine-release syndrome and neurotoxicity. CAR-T cell therapy led to a complete remission, with evidence of CAR-T cell trafficking to disease sites including the bone marrow and ovaries.

Mitochondrial augmentation of hematopoietic stem cells in children with single large-scale mitochondrial DNA deletion syndromes

Patients with single large-scale mitochondrial DNA (mtDNA) deletion syndromes (SLSMDs) usually present with multisystemic disease, either as Pearson syndrome in early childhood or as Kearns-Sayre syndrome later in life. No disease-modifying therapies exist for SLSMDs. We have developed a method to enrich hematopoietic cells with exogenous mitochondria, and we treated six patients with SLSMDs through a compassionate use program. Autologous CD34⁺ hematopoietic cells were augmented with maternally derived healthy mitochondria, a technology termed mitochondrial augmentation therapy (MAT). All patients had substantial multisystemic disease involvement at baseline, including neurologic, endocrine, or renal impairment. We first assessed safety, finding that the procedure was well tolerated and that all study-related severe adverse events were either leukapheresis-related or related to the baseline disorder. After MAT, heteroplasmy decreased in the peripheral blood in four of the six patients. An increase in mtDNA content of peripheral blood cells was measured in all six patients 6 to 12 months after MAT as compared baseline. We noted some clinical improvement in aerobic function, measured in patients 2 and 3 by sit-to-stand or 6-min walk testing, and an increase in the body weight of five of the six patients suffering from very low body weight before treatment. Quality-of-life measurements as per caregiver assessment and physical examination showed improvement in some parameters. Together, this work lays the ground for clinical trials of MAT for the treatment of patients with mtDNA disorders.

Rivaroxaban treatment among children with cancer-associated thromboembolism: Real-world data

This is the first study examining real-life data of pediatric cancer patients treated with rivaroxaban. Children with thrombocytopenia and high bleeding risk were excluded from previous clinical trials. Data regarding the safety and efficacy of rivaroxaban in pediatric cancer-associated thrombosis are scarce. Our case series included 16 children aged 7.5-17 years. Thrombus resolution rate in our study was comparable to results of previous studies. However, higher rates of thrombotic and bleeding complications were seen in our study as compared to previous reports, especially among patients with relapsed or refractory disease.

Pediatric glioblastoma cells are sensitive to drugs that inhibit eIF2α dephosphorylation and its phosphomimetic S51D variant

We found that pediatric glioblastoma (PED-GBM) cell lines from diffuse intrinsic pontine glioma (DIPG) carrying the H3K27M mutation or from diffuse hemispheric glioma expressing the H3G34R mutation are sensitive to the combination of vorinostat (a histone deacetylase inhibitor) and PARP-1 inhibitors. The combined treatment increased the phosphorylation of eIF2α (P-eIF2α) relative to each drug alone and enhanced the decrease in cell survival. To explore the role played by increased P-eIF2α in modulating PED-GBM survival and response to treatments, we employed brain-penetrating inhibitors of P-eIF2α dephosphorylation: salubrinal and raphin-1. These drugs increased P-eIF2α, DNA damage, and cell death, similarly affecting the sensitivity of DIPG cells and derived neurospheres to PARP-1 inhibitors. Interestingly, these drugs also decreased the level of eIF2Bϵ (the catalytic subunit of eIF2B) and increased its phosphorylation, thereby enhancing the effect of increased P-eIF2α. Transient transfection with the S51D phosphomimetic eIF2α variant recapitulated the effect of salubrinal and raphin-1 on PED-GBM survival and sensitivity to PARP-1 inhibitors. Importantly, either salubrinal or raphin-1 dramatically increased the sensitivity of DIPG cells to radiation, the main treatment modality of PED-GBM. Finally, PED-GBM was more sensitive than normal human astrocytes to salubrinal, raphin-1, and the treatment combinations described herein. Our results indicate that combinations of histone deacetylase inhibitors and PARP-1 inhibitors should be evaluated for their toxicity and efficacy in PED-GBM patients and point to drugs that increase P-eIF2α or modulate its downstream effectors as a novel means of treating PED-GBM.

Anti-Tumorigenic Effect of a Novel Derivative of 2-Hydroxyoleic Acid and the Endocannabinoid Anandamide on Neuroblastoma Cells

Modulation of the endogenous cannabinoid system has been suggested as a potential anticancer strategy. In the search for novel and less toxic therapeutic options, structural modifications of the endocannabinoid anandamide and the synthetic derivative of oleic acid, Minerval (HU-600), were done to obtain 2-hydroxy oleic acid ethanolamide (HU-585), which is an HU-600 derivative with the anandamide side chain. We showed that treatment of SK-N-SH neuroblastoma cells with HU-585 induced a better anti-tumorigenic effect in comparison to HU-600 as evidenced by 3-[4,5-dimethylthiazole-2-yl]-2,5-diphenyltetrazolium bromide assay, colony-forming assay, and migration assay. Moreover, HU-585 demonstrated pro-apoptotic properties shown by increased levels of activated caspase-3 following treatment and a better senescence induction effect in comparison to HU-600, as demonstrated by increased activity of lysosomal β-galactosidase. Finally, we observed that combined treatment of HU-585 with the senolytic drugs ABT-263 in vitro, and ABT-737 in vivo resulted in enhanced anti-proliferative effects and reduced neuroblastoma xenograft growth in comparison to treatment with HU-585 alone. Based on these results, we suggest that HU-585 is a pro-apoptotic and senescence-inducing compound, better than HU-600. Hence, it may be a beneficial option for the treatment of resistant neuroblastoma especially when combined with senolytic drugs that enhance its anti-tumorigenic effects.

Evaluation of the clinical impact of bone marrow cultures in current medical practice

The clinical yield and benefit of performing bone marrow cultures for various clinical indications has been challenged and their clinical necessity remains debatable. We sought to assess the clinical yield and benefit of performing routine bone marrow cultures and determine whether various clinical, laboratory, and imaging parameters were predictive of a diagnostic bone marrow culture. This was a single center retrospective analysis of all patients who underwent a bone marrow study comprising bone marrow cultures from January 1, 2012, through March 1, 2018. Baseline clinical data were extracted from the institution's electronic medical records system. The analyzed cohort consisted of 139 patients with a median age of 46 years (range 4 months to 85 years). The most common indication for a bone marrow study was workup of a fever of unknown origin (105 patients, 76%) while investigation for infection in immunocompromised patients accounted for 22 cases (16%) and suspected tuberculosis was the reason for acquisition of bone marrow cultures in 6 patients (4%). Only 3 patients had positive bone marrow cultures, yielding in 2 patients a diagnosis of Mycobacterium avium and in one patient a microbiologically unclassifiable fungal infection. A univariate analysis revealed that mean age, hemoglobin level, platelet count, c-reactive protein levels, gender, indication for bone marrow study, yield of blood cultures, and contribution of imaging studies and bone marrow pathology results were not significantly different between patients with diagnostic and non-diagnostic bone marrow cultures. Mean white blood cell count was found to be significantly lower in patients with diagnostic bone marrow cultures (2.4 × 10³/µL versus 8.7 × 10³/µL; P = 0.038). We conclude that for most patients, performance of bone marrow cultures holds limited clinical value.

Molecular and Functional Signatures Associated with CAR T Cell Exhaustion and Impaired Clinical Response in Patients with B Cell Malignancies

Despite the high rates of complete remission following chimeric antigen receptor (CAR) T cell therapy, its full capacity is currently limited by the generation of dysfunctional CAR T cells. Senescent or exhausted CAR T cells possess poor targeting and effector functions, as well as impaired cell proliferation and persistence in vivo. Strategies to detect, prevent or reverse T cell exhaustion are therefore required in order to enhance the effectiveness of CAR T immunotherapy. Here we report that CD19 CAR T cells from non-responding patients with B cell malignancies show enrichment of CD8⁺ cells with exhausted/senescent phenotype and display a distinct transcriptional signature with dysregulation of genes associated with terminal exhaustion. Furthermore, CAR T cells from non-responding patients exhibit reduced proliferative capacity and decreased IL-2 production in vitro, indicating functional impairment. Overall, our work reveals potential mediators of resistance, paving the way to studies that will enhance the efficacy and durability of CAR T therapy in B cell malignancies.

Hematopoietic cell transplantation in severe combined immunodeficiency: The SCETIDE 2006-2014 European cohort

BACKGROUND

Hematopoietic stem cell transplantation (HSCT) represents a curative treatment for patients with severe combined immunodeficiency (SCID), a group of monogenic immune disorders with an otherwise fatal outcome.

OBJECTIVE

We performed a comprehensive multicenter analysis of genotype-specific HSCT outcome, including detailed analysis of immune reconstitution (IR) and the predictive value for clinical outcome.

METHODS

HSCT outcome was studied in 338 patients with genetically confirmed SCID who underwent transplantation in 2006-2014 and who were registered in the SCETIDE registry. In a representative subgroup of 152 patients, data on IR and long-term clinical outcome were analyzed.

RESULTS

Two-year OS was similar with matched family and unrelated donors and better than mismatched donor HSCT (P < .001). The 2-year event-free survival (EFS) was similar in matched and mismatched unrelated donor and less favorable in mismatched related donor (MMRD) HSCT (P < .001). Genetic subgroups did not differ in 2-year OS (P = .1) and EFS (P = .073). In multivariate analysis, pretransplantation infections and use of MMRDs were associated with less favorable OS and EFS. With a median follow-up of 6.2 years (range, 2.0-11.8 years), 73 of 152 patients in the IR cohort were alive and well without Ig dependency. IL-2 receptor gamma chain/Janus kinase 3/IL-7 receptor-deficient SCID, myeloablative conditioning, matched donor HSCT, and naive CD4 T lymphocytes >0.5 × 10^e3/μL at +1 year were identified as independent predictors of favorable clinical and immunologic outcome.

CONCLUSION

Recent advances in HSCT in SCID patients have resulted in improved OS and EFS in all genotypes and donor types. To achieve a favorable long-term outcome, treatment strategies should aim for optimal naive CD4 T lymphocyte regeneration.

Upfront rational therapy in BRAF V600E mutated pediatric ameloblastoma promotes ad integrum mandibular regeneration

Ameloblastoma is a neoplasm arising in the craniofacial skeleton. Proliferating odontogenic epithelial cells comprise this benign, yet locally invasive tumor, often causing severe disfiguration. High recurrence rate entails ablative surgical resection, which is the current standard of care, resulting in subsequent critical size osteocutaneous defects. The high incidence of BRAF mutations in ameloblastoma, most notably the BRAF V600E mutation, enabled the use of BRAF inhibiting agent in a neoadjuvant setting. In this investigator-initiated, open-label study, three consecutive pediatric patients, with confirmed BRAF V600E ameloblastoma deemed marginally resectable, were treated with BRAF inhibiting agents, prior to undergoing surgery. The use of upfront BRAF inhibitor treatment resulted in substantial tumor regression, allowing for non-mutilating complete surgical removal, ad integrum bone regeneration and organ preservation. All patients showed a marked radiologic and clinical response to medical treatment, enabling successful conservative surgery. Microscopically, all patients showed evidence of minimal residual tumor with extensive tumor necrosis, fibrosis and generation of new bone. At a median follow-up of 31 months, all patients remained free of disease. Face preservation therapy was achieved in pediatric patients presenting with BRAF V600E mutated ameloblastoma. Our study demonstrates the translational potential of targeted therapy as a neoadjuvant agent. Patient-specific organ preservation therapy should be considered as the new standard of care in ameloblastoma, mainly for children and adolescents.

Improved transplant outcomes with myeloablative conditioning for hemophagocytic lymphohistiocytosis in HLA-matched and mismatched donors: a national multicenter retrospective study

We report the results of national retrospective study of 45 children with hemophagocytic lymphohistiocytosis (HLH) who underwent allogeneic hematopoietic stem-cell transplantation (HSCT) in Israel between the years 2000-2018. Donors were either HLA-matched (n = 26), partially mismatched (n = 7), haploidentical (n = 8), or cord-blood (n = 4). Myeloablative conditioning (MAC) was used in 20 procedures, and reduced-intensity conditioning (RIC) in 25. Forty-two patients engrafted, two had primary graft failure (one successfully retransplanted), one died prior to engraftment, and two developed secondary graft failure. Of the eight patients who had mixed donor chimerism at day 30 (5-95%), five achieved stable mixed or full donor chimerism. The 5-year probabilities of overall survival and event-free survival (EFS) were 86% and 82%, respectively. Five-year EFS was lower for patients receiving RIC compared to MAC (72% vs. 100%, p = 0.018) and following alternative-donor transplant (68% vs. 92% for HLA-matched donors, p = 0.034), mostly due to increased transplant-related mortality (TRM). Thus, both HLA-matched and alternative donor transplant procedures may benefit form a myeloablative conditioning regimen.

Trajectories and risk factors for anxiety and depression in children and adolescents with cancer: A 1-year follow-up

BACKGROUND

There is limited data on the longitudinal trajectories of psychiatric disorders in children with cancer and risk factors for their persistence. The current study aimed to longitudinally assess the trajectories and risk factors for anxiety and depressive symptoms and disorders in children and adolescents with cancer.

METHODS

Children and adolescents with cancer and their parents completed the Patient-Reported Outcomes Measurement Information System (PROMIS) Depression and Anxiety Module and were interviewed by the semi-structured Affective and Anxiety Modules of the Kiddie Schedule for Affective Disorders and Schizophrenia for School-Age Children (K-SADS), at 4 time points, 1, 4, 7, and 12 months following the diagnosis of cancer.

RESULTS

Of the 99 patients enrolled, 48% met criteria for anxiety and/or depressive disorders at least once during the follow-up period. There was a significant decrease in PROMIS pediatric and parent anxiety and depression scores (all p's < 0.01) and in the rate of depressive disorders over time (p = 0.02), while rates of anxiety disorders remained stable. Anxiety PROMIS pediatric and parent scores at baseline, having brain tumors and being in the acute treatment phase significantly predicted the presences of anxiety disorders at endpoint.

CONCLUSIONS

Our results highlight the importance of screening for anxiety and disorders in children with cancer, especially among those with brain tumors and at the acute phase of treatment.

Characteristics and risk factors of infections following CD28-based CD19 CAR-T cells

CAR T-cells are approved for the treatment of relapsed and refractory leukemia and lymphoma. Here, we studied the infectious complications in 88 patients treated with CD28-based CD19 CAR T-cells. Overall, 36 infections were documented in 24 patients within the first month after CAR T-cell infusion: Six events of bacteremia, sixteen focal bacterial infections, and fourteen systemic or localized viral infections. Seven patients had nine infectious episodes beyond the first 30 days of follow-up, including three events of bacteremia, three focal bacterial, two viral and one fungal infection. The presence of neutropenia, neutropenic fever and lack of response to treatment were associated with a higher rate of infections. Children had less severe infections than adults. In a multivariate analysis lack of response to treatment was the only significant risk factor. Overall, the incidence of bacterial infections following CAR T-cells is modest especially in children and in patients responding to therapy.

MBRS-04. MEDULLOBLASTOMA DETECTION BY BLOOD TEST

INTRODUCTION

Long non coding RNAs (lincRNAs) are functionally defined as transcripts longer than 200 nucleotides in length with no protein coding potential. lincRNA involvement in human cancers etiology is being increasingly proved. Cancer-secreted long non-coding RNAs (lncRNAs) in exosomes are emerging mediators of cancer-host cross talk communication in tumor microenvironments. The ability to monitor and detect tumor markers in real time enables access to tumor biology and may allow highly personalized treatment for each patient. METHODS AND

RESULTS

We analyzed RNA sequencing of 64 Medulloblastoma samples and quantified the genome wide long non coding RNAs (lincRNA) expression levels. We identified a lincRNA that is distinctively highly expressed in group 4 (MB4). MB4 expression was further examined in microarray analysis on a larger cohort of medulloblastoma patient samples and a large cohort (n=1405) of patient samples that include normal brain and different brain tumor samples. MB4 proved to be specific and highly expressed in group 4 Medulloblastoma. MB4 was detected in the plasma of medulloblastoma patients with active disease, or subtotal resection. MB4 was not detected in patients that their tumors were resected. MB4 expression is not detected in the serum of medulloblastoma type SHH, penioblastoma, ewing sarcoma and neuroblastoma patients.

CONCLUSIONS

We have found that MB4 lncRNA is a highly specific medulloblastoma tumor biomarker and is sensitive and noninvasive biomarker that can be quantified from a blood test. MB4 can be a good diagnostic marker, and in future both may also be a good target for therapy.

HGG-04. ZINC ENHANCES TEMOZOLOMIDE CYTOTOXICITY IN PEDIATRIC GLIOBLASTOMA MULTIFORME MODEL SYSTEM

BACKGROUND

Temozolomide (TMZ) is an alkylating agent that has become the mainstay treatment of the most malignant brain cancer, glioblastoma multiforme (GBM). Unfortunately only a limited number of patients respond to it positively. We have shown that zinc metal reestablishes chemosensitivity in adult GBM in vitro and also in vivo but this effect has not been tested with pediatric GBM.

METHODS

Using Human pediatric glioblastoma cell lines- KNS42 (mutant p53/ MGMT [+]) and SF188 (mutant p53/ MGMT [-]), we investigated whether addition of zinc to TMZ enhances its cytotoxicity against GBM.

RESULTS

In vitro cell viability analysis showed that the cytotoxic activity of TMZ was substantially increased with addition of zinc and this response was accompanied by an elevation of p21, PUMA, BAX and a decrease in growth fraction as manifested by low ki67. Beta gal analysis showed that most of the remaining cells after the combination therapy are in senescence state. In order to eliminate the senescent population created as a result of the combined treatment of TMZ and Zinc, we decided to use a senolytic agent Navitoclax (ABT-263) that was demonstrated to be effective in reducing senescent cells by specific inhibition of Bcl-2, Bcl-XL and Bcl-w. Following the addition of Navitoclax to the combined treatment, SF188 cells, but not KNS42, show a significance reduction in viability compare to the combination treatment.

CONCLUSIONS

Our results suggest that zinc may serve as a potentiator of TMZ therapy in pediatric GBM patients and using a second hit with senolytic drug in some cases may be even more beneficial.

Head-to-head comparison of in-house produced CD19 CAR-T cell in ALL and NHL patients

Background

CD19 chimeric antigen receptor T (CAR-T) cells demonstrate remarkable remission rates in pediatric and adult patients with refractory or relapsed (r/r) acute lymphoblastic leukemia (ALL) and non-Hodgkin's lymphoma (NHL). In 2016, we initiated a clinical trial with in-house produced CD19 CAR-T cells with a CD28 co-stimulatory domain. We analyzed, for the first time, differences in production features and phenotype between ALL and NHL patients.

Methods

Non-cryopreserved CAR-T cells were produced from patients’ peripheral blood mononuclear cells within 9 to 10 days. 93 patients with r/r ALL and NHL were enrolled under the same study. CAR-T cells of ALL and NHL patients were produced simultaneously, allowing the head-to-head comparison.

Results

All patients were heavily pretreated. Three patients dropped out from the study due to clinical deterioration (n=2) or production failure (n=1). Cells of ALL patients (n=37) expanded significantly better and contained more CAR-T cells than of NHL patients (n=53). Young age had a positive impact on the proliferation capacity. The infusion products from ALL patients contained significantly more naïve CAR-T cells and a significantly higher expression of the chemokine receptor CXCR3. PD-1, LAG-3, TIM-3, and CD28 were equally expressed. 100% of ALL patients and 94% of NHL patients received the target dose of 1×10e6 CAR-T/kg. The overall response rate was 84% (30/36) in ALL and 62% (32/52) in NHL. We further compared CAR-T cell infusion products to tumor infiltrating lymphocytes (TIL), another common type of T cell therapy, mainly clinically effective in solid tumors. CAR-T cells contained significantly more naïve T cells and central memory T cells and significantly less CCR5 compared to TIL infusion products.

Conclusions

The in-house production of CAR-T cells is highly efficient and fast. Clinical response rate is high. CAR-T cells can be successfully produced for 99% of patients in just 9 to 10 days. Cells derived from ALL patients demonstrate a higher proliferation rate and contain higher frequencies of CAR-T cells and naïve T cells than of NHL patients. In addition, understanding the differences between CAR-T and TIL infusion products, may provide an angle to develop CAR-T cells for the treatment of solid tumors in the future.

Trial registration number

ClinicalTrials.gov; CAR-T: NCT02772198, First posted: May 13, 2016; TIL: NCT00287131, First posted: February 6, 2006.

Venous Thromboembolism and Its Risk Factors in Children with Acute Lymphoblastic Leukemia in Israel: A Population-Based Study

Venous thromboembolism (VTE) is a serious complication of acute lymphoblastic leukemia (ALL) therapy. The aim of this population-based study was to evaluate the rate, risk factors, and long-term sequelae of VTE in children treated for ALL. The cohort included 1191 children aged 1-19 years diagnosed with ALL between 2003-2018, prospectively enrolled in two consecutive protocols: ALL-IC BFM 2002 and AIEOP-BFM ALL 2009. VTEs occurred in 89 patients (7.5%). Long-term sequelae were uncommon. By univariate analysis, we identified four significant risk factors for VTEs: Severe hypertriglyceridemia (p = 0.005), inherited thrombophilia (p < 0.001), age >10 years (p = 0.015), and high-risk ALL group (p = 0.039). In addition, the incidence of VTE was significantly higher in patients enrolled in AIEOP-BFM ALL 2009 than in those enrolled in ALL-IC BFM 2002 (p = 0.001). Severe VTE occurred in 24 children (2%), all of whom had at least one risk factor. Elevated triglyceride levels at diagnosis did not predict hypertriglyceridemia during therapy. In a multivariate analysis of 388 children, severe hypertriglyceridemia and inherited thrombophilia were independent risk factors for VTE. Routine evaluation for these risk factors in children treated for ALL may help identify candidates for intervention.

A three-tier process for screening depression and anxiety among children and adolescents with cancer

OBJECTIVE

To establish and to evaluate the effectiveness of a three-tier screening process of depressive and anxiety disorders among children and adolescents with cancer based on questionnaires (first tier), semistructured psychiatric interviews (second tier), and referral for psychiatric assessment and recommendations for treatment (third tier). We also aimed to determine the rates of depressive and anxiety disorders among participants.

METHODS

Participants and their parents completed the Patient Reported Outcomes Measurement Information System (PROMIS) Depression and Anxiety modules. Then, they were interviewed separately using the semistructured Affective and Anxiety Modules of the Schedule for Affective Disorders and Schizophrenia for School-Age Children (K-SADS). PROMIS cutoff values for diagnosing depressive and anxiety disorders, based on the K-SADS, were calculated by receiver-operating characteristics (ROCs).

RESULTS

Of 91 participants 34 (37.4%) aged 7 to 21 years with cancer met the K-SADS criteria for depressive and/or anxiety disorders. The results of the ROC analyses were stronger for depressive disorders than for anxiety disorders and for more severe cases. The cutoff of 13 on the child-reported PROMIS for a major depressive episode had a sensitivity of 0.80 and a specificity of 0.82, and a cutoff of 14 on the parent-reported PROMIS for generalized anxiety disorder had a sensitivity of 0.78 and a specificity of 0.79.

CONCLUSIONS

Using the K-SADS, we found that anxiety and depressive disorders are very common in youngsters with cancer. The three-tier screening process we developed for depression and anxiety in this population provides practical cutoff values for identifying depressive and anxiety disorders in children with cancer.

Congenital neutropenia with variable clinical presentation in novel mutation of the SRP54 gene

BACKGROUND

The SRP54 (signal recognition protein 54) is a conserved component of the ribonucleoprotein complex that mediates cotranslational targeting and translocation of proteins to the endoplasmic reticulum. In 2017, mutations in the gene have been described as a cause of congenital neutropenia with or without pancreatic insufficiency, and since then, only limited cases were added to the literature.

METHODS

Two patients with neutropenia underwent hematological, immunological, and genetic work-up, including lymphocyte phenotyping, immunoglobulins, and complement levels, antineutrophil and antinuclear antibodies, bone marrow FISH panel for myelodysplastic syndrome, whole-exome sequencing, and in silico proteomic analysis.

RESULTS

Clinical findings in the two families revealed a wide spectrum of immunological and clinical manifestations, ranging from mild asymptomatic neutropenia during febrile illnesses to severe neutropenia and life-threatening infection requiring leg amputation. Immunological and hematological work-up showed isolated neutropenia with normal lymphocyte subpopulations, immunoglobulin and complement levels, and negative autoimmune tests. Bone marrow aspirations showed variability ranging from normal myelopoiesis to myeloid maturation arrest at the promyelocytic stage, with normal FISH panel for myelodysplastic syndrome. Genetic analysis identified a novel, de novo, in-frame deletion in the SRP54 gene, c.342-344delAAC, p.T115del. In silico proteomic analysis suggested impaired SRP54 protein function due to reduced GTP activity and stability.

CONCLUSIONS

We describe congenital neutropenia with variable clinical presentation in novel mutation of the SRP54 gene.

Essential thrombocythemia A retrospective case series

BACKGROUND

Essential thrombocythemia (ET) is rare in children, and pediatric guidelines are lacking. Therefore, we aimed to evaluate ET diagnosis and treatment in a pediatric cohort.

PROCEDURE

Data of patients with ET from three hospitals were reviewed. Molecular diagnosis included JAK2V617F, CALR, and MPL mutations. Patients were evaluated for acquired von Willebrand syndrome (AVWS). Follow-up included clinical symptoms, adverse events, and treatment.

RESULTS

Twelve children (median age: 8 years, range 1-14.5) were included. Mean lag period between the first documentation of thrombocytosis until ET diagnosis was 36 months. Six patients were positive for JAK2V617F and two for CALR mutations. In six of nine patients, AVWS was diagnosed. At diagnosis, only 33% of patients started therapy with aspirin (n = 4) and hydroxyurea (n = 2). In three of eight untreated patients, therapy was added during follow-up. The cohort was followed for a median of 32.5 months (range: 4-108 months). Clinical follow-up disclosed vascular complications in 4 of 12 patients (deep vein thrombosis, n = 1; transient ischemic attack, n = 3). Two females experienced excessive bleeding; both were diagnosed with AVWS. Neither leukemia nor myelofibrosis evolved in our cohort.

CONCLUSION

Increased awareness to pediatric ET is warranted, as delayed diagnosis is common. Compared to adults, AVWS may be more prevalent among children with ET.

Feasibility of leukapheresis for CAR T-cell production in heavily pre-treated pediatric patients

BACKGROUND

Autologous CD19 chimeric-antigen receptor (CAR) T-cells are an effective salvage therapy for patients with relapsed or refractory B cell malignancies. The essential first step in the production is the collection of mature lymphocytes through leukapheresis. It is a challenging procedure given the fact patients are heavily pretreated and the special considerations of pediatric apheresis.

METHODS

We analyzed the data of leukapheresis outcome for CAR T production in a phase 1b/2 clinical trial enrolling 34 children, adolescents and young adults with relapsed or refractory B-cell malignancies.

RESULTS

All patients underwent a single leukapheresis. Given a short production time for CAR T-cells, most patients received bridging therapy prior to apheresis. Leukapheresis was performed using peripheral venous access in the majority (82%) of patients, and the remainder required arterial line or central venous access. T-cell collection efficiency (CE) was variable with a median of 18%. No apheresis-related adverse events were noted, and all procedures were successful but two: one resulting in lower than target dose (1 × 10⁶ CAR + cells/kg) and the other in failure of CAR T-cell production.

CONCLUSIONS

Collection of sufficient T-cells in heavily pretreated pediatric patients via a single apheresis procedure is feasible even with relatively low T-cell CE.

Poorer outcome of childhood acute lymphoblastic leukemia in the Bedouin population: A report from the Berlin-Frankfurt-Muenster-based Israeli national protocols

BACKGROUND

Therapy outcomes for childhood acute lymphoblastic leukemia (ALL) had substantially improved in the last decades, but variability across racial and ethnic groups was identified in some clinical studies. In this study, we aimed to investigate whether such a difference in outcome is found in the diverse ethnicities in Israel as well.

METHODS

A retrospective study was conducted among 1154 patients (855 Jews, 195 Muslims, 52 Bedouins, 26 Druze, and 26 others) aged 1 to 21 years, who were diagnosed with ALL between 1989 and 2011 and were treated according to the same Berlin-Frankfurt-Muenster-based Israel National Study protocols.

RESULTS

Bedouins had a higher incidence of t(1;19) (16% vs 3% for non-Bedouins) and a lower incidence of high-hyperdiploidy (10% vs 25% for non-Bedouins) (P = 0.01). Five-year event-free survival (EFS) and overall survival (OS) were poorer for the Bedouins (60.3% ± 7.2% and 63.1% ± 7.2%, respectively) compared with the Jews, Muslims, and Druze (80.4% ± 1.4%, 77.3% ± 3.2%, and 84% ± 7.3%, respectively, for EFS [P = 0.02], and 86.3% ± 1.2%, 82.3% ± 2.9%, and 88.3% ± 6.4%, respectively, for OS [P = 0.002]). Adherence to intensive chemotherapy was similar between the Muslims and the Bedouins.

CONCLUSIONS

Our findings suggest that the Bedouins, a highly inbred ethnic Arab people, may be considered a higher risk group that may need more intensive chemotherapy and/or supportive care in order to improve their outcome.

Mucormycosis in children with haematological malignancies is a salvageable disease: a report from the Israeli Study Group of Childhood Leukemia

Mucormycosis has emerged as an increasingly important cause of morbidity and mortality in immunocompromised patients, but contemporary data in children are lacking. We conducted a nationwide multicentre study to investigate the characteristics of mucormycosis in children with haematological malignancies. The cohort included 39 children with mucormycosis: 25 of 1136 children (incidence 2·2%) with acute leukaemias prospectively enrolled in a centralized clinical registry in 2004-2017, and an additional 14 children with haematological malignancies identified by retrospective search of the databases of seven paediatric haematology centres. Ninety-two percent of mucormycosis cases occurred in patients with acute leukaemias. Mucormycosis was significantly associated with high-risk acute lymphoblastic leukaemia (OR 3·75; 95% CI 1·51-9·37; P = 0·004) and with increasing age (OR 3·58; 95% CI 1·24-9·77; P = 0·01). Fifteen patients (38%) died of mucormycosis. Rhinocerebral pattern was independently associated with improved 12-week survival (OR 9·43; 95% CI 1·47-60·66; P = 0·02) and relapsed underlying malignancy was associated with increased 12-week mortality (OR 6·42; 95% CI, 1·01-40·94; P = 0·05). In patients receiving frontline therapy for their malignancy (n = 24), one-year cumulative mucormycosis-related mortality was 21 ± 8% and five-year overall survival was 70 ± 8%. This largest paediatric population-based study of mucormycosis demonstrates that children receiving frontline therapy for their haematological malignancy are often salvageable.

Blinatumomab as a bridge to further therapy in cases of overwhelming toxicity in pediatric B-cell precursor acute lymphoblastic leukemia: Report from the Israeli Study Group of Childhood Leukemia

Tremendous progress in the therapy of pediatric acute lymphoblastic leukemia (ALL) has been achieved through combination cytotoxic chemotherapy, leading to high cure rates, at the cost of significant life-threatening toxicity. The bispecific T-cell engager blinatumomab, recently approved for relapsed/refractory ALL, has a unique nonmyelotoxic toxicity profile. As blinatumomab causes B-cell depletion, the safety of its use during severe chemotherapy-induced toxicity is unclear. We report 11 pediatric patients with ALL, treated with blinatumomab following overwhelming chemotherapy-associated toxicity, with recovery of all patients and successful bridging to further antileukemia therapy. Blinatumomab can be considered for rare patients who cannot tolerate cytotoxic therapy.

Characterization and genotype-phenotype correlation of patients with Fanconi anemia in a multi-ethnic population

Fanconi anemia (FA), an inherited bone marrow failure (BMF) syndrome, caused by mutations in DNA repair genes, is characterized by congenital anomalies, aplastic anemia, high risk of malignancies and extreme sensitivity to alkylating agents. We aimed to study the clinical presentation, molecular diagnosis and genotype-phenotype correlation among patients with FA from the Israeli inherited BMF registry. Overall, 111 patients of Arab (57%) and Jewish (43%) descent were followed for a median of 15 years (range: 0.1-49); 63% were offspring of consanguineous parents. One-hundred patients (90%) had at least one congenital anomaly; over 80% of the patients developed bone marrow failure; 53% underwent hematopoietic stem-cell transplantation; 33% of the patients developed cancer; no significant association was found between hematopoietic stem-cell transplant and solid tumor development. Nearly 95% of the patients tested had confirmed mutations in the Fanconi genes FANCA (67%), FANCC (13%), FANCG (14%), FANCJ (3%) and FANCD1 (2%), including twenty novel mutations. Patients with FANCA mutations developed cancer at a significantly older age compared to patients with mutations in other Fanconi genes (mean 18.5 and 5.2 years, respectively, P=0.001); however, the overall survival did not depend on the causative gene. We hereby describe a large national cohort of patients with FA, the vast majority genetically diagnosed. Our results suggest an older age for cancer development in patients with FANCA mutations and no increased incidence of solid tumors following hematopoietic stem-cell transplant. Further studies are needed to guide individual treatment and follow-up programs.

NCAM1/FGF module serves as a putative pleuropulmonary blastoma therapeutic target

Pleuropulmonary blastoma (PPB) is a rare pediatric lung neoplasm that recapitulates developmental pathways of early embryonic lungs. As lung development proceeds with highly regulated mesenchymal-epithelial interactions, a DICER1 mutation in PPB generates a faulty lung differentiation program with resultant biphasic tumors composed of a primitive epithelial and mesenchymal stroma with early progenitor blastomatous cells. Deciphering of PPB progression has been hampered by the difficulty of culturing PPB cells, and specifically progenitor blastomatous cells. Here, we show that in contrast with in-vitro culture, establishment of PPB patient-derived xenograft (PDX) in NOD-SCID mice selects for highly proliferating progenitor blastoma overexpressing critical regulators of lung development and multiple imprinted genes. These stem-like tumors were sequentially interrogated by gene profiling to show a FGF module that is activated alongside Neural cell adhesion molecule 1 (NCAM1). Targeting the progenitor blastoma and these transitions with an anti-NCAM1 immunoconjugate (Lorvotuzumab mertansine) inhibited tumor growth and progression providing new paradigms for PPB therapeutics. Altogether, our novel in-vivo PPB xenograft model allowed us to enrich for highly proliferating stem-like cells and to identify FGFR and NCAM1 as two key players that can serve as therapeutic targets in this poorly understood and aggressive disease.

Elevated NLR May Be a Feature of Pediatric Brain Cancer Patients

Pediatric brain tumors are the most common solid tumor type and the leading cause of cancer-related death in children. The immune system plays an important role in cancer pathogenesis and in the response to immunotherapy treatments. T lymphocytes are key elements for the response of the immune system to cancer cells and have been associated with prognosis of different cancers. Neutrophils on the other hand, which secrete pro-angiogenic and anti-apoptotic factors, enhance the ability of tumor cells to grow and develop into metastases. We conducted a retrospective study of 120 pediatric brain cancer patients and 171 elective pediatric patients hospitalized in Dana Children's Hospital and Sheba Medical Center. Data on age, sex, treatment, lymphocyte, neutrophil, and monocyte count were collected from routinely performed preoperative blood tests. Neutrophil-to-lymphocyte ratio (NLR), and the lymphocyte-to-monocyte ratio (LMR) were calculated and significance was determined by paired T test. p < 0.05 was considered as statistically significant. NLR was significantly higher in the pediatric brain cancer patients. The high NLR in pediatric brain cancer patients is the result of a combination of low lymphocytes and high neutrophils. Both of these factors can have a role in cancer development and propagation and also in response to therapy.

The Gut-Brain Axis, Paving the Way to Brain Cancer

The gut-brain axis formed by blood and lymphatic vessels paves the way for microbiota to impact the brain. Bacterial populations in the gut are a good candidate for a nongenetic factor contributing substantively to brain tumor development and to the success of therapy. Specifically, suppression of the immune system and induction of inflammation by microbiota sustain proliferative signaling, limit cell death, and induce angiogenesis as well as invasiveness. In addition, altered microbial metabolites and their levels could stimulate cell proliferation. We propose here a novel gear model connecting these complex interdisciplinary fields. Our model may impact mechanistic studies of brain cancer and better treatment outcomes through precision oncology.

Fluorodeoxyglucose Detected Changes in Brain Metabolism After Chemotherapy in Pediatric Non-Hodgkin Lymphoma

BACKGROUND

Potential neurocognitive dysfunction after chemotherapy is a worrisome long-term outcome. Our objective was to evaluate the effect on brain metabolism in pediatric patients with non-central nervous system cancer treated with chemotherapy by analyzing brain data from serial whole-body fluorodeoxyglucose positron emission tomography/computed-tomography (FDG-PET/CT) scans taken before and sequentially after therapy.

METHODS

Fourteen pediatric patients diagnosed with lymphoma and treated with systemic and prophylactic intrathecal chemotherapy were included. All patients had baseline pretreatment whole-body FDG-PET/CT and at least one post-therapy study preformed as part of standard surveillance. Brain positron emission tomography data were quantitatively analyzed for normalized fluorodeoxyglucose uptake in various brain regions. A generalized estimating equation approach was used to evaluate temporal changes after chemotherapy.

RESULTS

Median time of follow-up surveillance positron emission tomography-computed-tomography was 456 days after chemotherapy course. Various brain regions demonstrated significant changes in fluorodeoxyglucose uptake as a function of time passed since chemotherapy. Increased fluorodeoxyglucose uptake was noted in the parietal and cingulate cortexes. Decreased fluorodeoxyglucose uptake was demonstrated in deep gray matter nuclei and in the brainstem.

CONCLUSIONS

Our study provides novel insights into long-standing and progressive changes in regional glucose metabolism after chemotherapy in pediatric cancer population, lasting long after the end of therapy and reaching clinical remission. Expanding the utility of regular surveillance fluorodeoxyglucose positron emission tomography to a detailed quantitative assessment of regional brain metabolism after chemotherapy can provide valuable information on individual chemotherapy-related neuromodulation and facilitate the development of strategies to minimize neurocognitive side effects.

Sustained Response to Imatinib in a Pediatric Patient with Concurrent Myeloproliferative Disease and Lymphoblastic Lymphoma Associated with a CCDC88C-PDGFRB Fusion Gene

BACKGROUND

The WHO defined myeloid and lymphoid neoplasms (MLN) with eosinophilia associated with PDGFRB, PDGFRA, FGFR1 rearrangements as a new entity in 2016. PDGFRB-rearranged MLN sensitive to imatinib were described in adult patients. We report the first pediatric patient with PDGFRB-rearranged myeloproliferative disorder associated with T-lymphoblastic lymphoma bearing the t(5; 14)(q33;q32) translocation who was successfully treated with imatinib only. Methods/Aims: Analysis of bone marrow and peripheral blood cells by fluorescent in situ hybridization identified the PDGFRB partner as CCDC88C. Whole genome sequencing of the patient's DNA identified the exact junction site, confirmed by PCR amplification and Sanger sequencing. A real-time quantitative PCR assay was designed to quantify the fused CCDC88C-PDGFRB product.

RESULTS

A 2.5-year-old boy was diagnosed with myeloproliferative disorder and eosinophilia associated with lymphoblastic lymphoma both bearing the CCDC88C-PDGFRB fusion. Imatinib therapy resulted in rapid clinical, hematological, and cytogenetic response. Molecular response to treatment was monitored by a real-time PCR assay specific for the CCDC88C- PDGFRB fusion.

CONCLUSION

This is the first description of MLN with eosinophilia in the pediatric age group. Response to treatment with imatinib only was monitored by specific quantitative PCR assay with sustained remission lasting 5.5 years from diagnosis.

Locally produced CD19 CAR T cells leading to clinical remissions in medullary and extramedullary relapsed acute lymphoblastic leukemia

Autologous CD19 chimeric-antigen receptor (CAR) T cells demonstrated remarkable remission rates in relapsed and refractory acute lymphoblastic leukemia (R/R ALL). Here, we report results from a phase 1b/2 study of in-house produced CD19 CAR with a CD28 costimulatory domain. Twenty-one patients with R/R ALL were enrolled, and 20 infused. The median age was 11 years (range, 5-48). Patients had a median of 4 prior regimens, including blinatumomab in 6 and prior stem-cell transplantation in 10. In total 8 patients had extramedullary (EM) leukemic involvement, and prior to lymphodepletion and CAR 7 had active lesions, a group underrepresented in previous trials. In vivo expansion of CAR T cells was observed in 18 patients. In total 16 patients developed cytokine release syndrome, and 11 patients developed neurotoxicity, with no toxic deaths. All responding patients were referred to an allogeneic hematopoietic stem-cell transplantation. The remission rate was 90%, including resolution of all refractory EM sites. Four responding patients relapsed, 3 who had a PCR-MRD positive remission at 28 days following CAR-T cells and 1 patient 21 months after an MRD-negative response. The estimated 1-year event-free survival and overall survival are 73% and 90%, respectively. Patients with R/R EM ALL may also benefit from CAR-T cell therapy.

Successful treatment of invasive mucormycosis with isavuconazole in pediatric patients

BACKGROUND

Invasive mold infections (IMIs) are a leading cause of mortality among immunocompromised patients. Isavuconazole is a new drug that shows promise in the adult population for the treatment of IMIs. No data regarding the use of isavuconazole in pediatric patients have been published.

METHODS

Patients with a diagnosis of IMI from our pediatric hemato-oncology division, treated with isavuconazole between 2010 and 2016, were identified using the hospital's computerized database. Data including demographics, clinical course, and outcome were collected. Pharmacokinetic samples were obtained from two younger patients to guide dosing.

RESULTS

In total, three patients (4.5, 5, and 19 years of age) with invasive mucormycosis who were treated with isavuconazole were identified. All patients were treated with isavuconazole as a second line therapy and experienced improvement following the initiation of this treatment.

CONCLUSIONS

Based on our limited clinical experience, isavuconazole may be a safe and effective treatment option for children and adolescents afflicted by IMI. Prospective clinical trials should be performed in order to evaluate the pharmakokinetics and safety of isavuconazole in the pediatric population.

In Vivo Expansion of Cancer Stemness Affords Novel Cancer Stem Cell Targets: Malignant Rhabdoid Tumor as an Example

Cancer stem cell (CSC) identification relies on transplantation assays of cell subpopulations sorted from fresh tumor samples. Here, we attempt to bypass limitations of abundant tumor source and predetermined immune selection by in vivo propagating patient-derived xenografts (PDX) from human malignant rhabdoid tumor (MRT), a rare and lethal pediatric neoplasm, to an advanced state in which most cells behave as CSCs. Stemness is then probed by comparative transcriptomics of serial PDXs generating a gene signature of epithelial to mesenchymal transition, invasion/motility, metastasis, and self-renewal, pinpointing putative MRT CSC markers. The relevance of these putative CSC molecules is analyzed by sorting tumorigenic fractions from early-passaged PDX according to one such molecule, deciphering expression in archived primary tumors, and testing the effects of CSC molecule inhibition on MRT growth. Using this platform, we identify ALDH1 and lysyl oxidase (LOX) as relevant targets and provide a larger framework for target and drug discovery in rare pediatric cancers.

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Human malignant rhabdoid tumor (MRT) can be propagated in vivo as tumor xenografts

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Long-term propagated PDX enrich for CSC frequency with no need for immune selection

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Distinct gene signature in stem-like MRT xenografts reveals putative CSC biomarkers

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Screening of putative CSC biomarkers allows identification of therapeutic targets

Cytoreductive surgery (CRS) and hyperthermic intraperitoneal chemotherapy (HIPEC) for disseminated intra-abdominal malignancies in children-a single-institution experience

PURPOSE

Our purpose was to present our institutional experience with performing complete cytoreduction surgery and heated intraoperative chemotherapy (CRS-HIPEC) for children with disseminated intraabdominal malignancies, guided by a leading international center performing CRS-HIPEC in children.

METHODS

Retrospective chart review of all cases of CRS-HIPEC in children in our institution, examining diagnosis, preoperative management, operative management, postoperative treatment, short term outcome including length of stay and complications, and long term outcome including survival and recurrence of disease.

RESULTS

9 children underwent CRS-HIPEC over 48months. The mean age of the patients was 8years. Tumors were: rhabdomyosarcoma (RMS), mesothelioma, Sertoli-Leydig, desmoplastic small round cell tumor, colon carcinoma and Wilms' tumor. Most patients received intraperitoneal cisplatin. Short term outcome was very good with median length of hospital stay of 13days and low rate of complications. Seven patients were alive at last follow up. Five patients developed a recurrent disease. Recurrence was intraabdominal in two of these patients.

CONCLUSIONS

CRS-HIPEC for children with disseminated intraabdominal malignancies performed in a dedicated institution and with guidance by a leading international center can be performed safely.

TYPE OF STUDY

Treatment study.

LEVEL OF EVIDENCE

IV.

MutT homolog 1 counteracts the effect of anti-neoplastic treatments in adult and pediatric glioblastoma cells

Glioblastoma, a fatal disease in both adult and pediatric patients, currently has limited treatment options that offer no more than temporary relief. Our experiments with adult and pediatric glioblastoma cell lines showed that radiation induces a dose-dependent increase in the level of MutT homolog 1 (MTH1) - an enzyme that hydrolyzes oxidized purine nucleoside triphosphates. Similarly, the combination of vorinostat, which is a histone deacetylase inhibitor, and ABT-888, which is a PARP-1 inhibitor, enhanced clonogenic death and increased the MTH1 level, relative to each treatment alone. This result suggests that the MTH1 level is directly related to the damage that is inflicted upon the cells, and its activity protects them against anti-neoplastic therapy. Indeed, the MTH1 inhibitor TH588 and MTH1 siRNA increased glioblastoma's response to both radiation and the combination of vorinostat and ABT-888. TH588 also inhibited glioblastoma's capacity for migration and invasion. In normal fibroblasts, low radiation doses and the combination of vorinostat and ABT-888 decreased the level of the enzyme. TH588 did not alter the fibroblasts’ response to radiation and only mildly affected their response to the combination of vorinostat and ABT-888.

In summary, the inhibition of MTH1 is required to better realize the therapeutic potential of anti-neoplastic treatments in glioblastoma.

Zinc enhances temozolomide cytotoxicity in glioblastoma multiforme model systems

Temozolomide (TMZ) is an alkylating agent that has become the mainstay treatment of the most malignant brain cancer, glioblastoma multiforme (GBM). Unfortunately only a limited number of patients positively respond to it. It has been shown that zinc metal reestablishes chemosensitivity but this effect has not been tested with TMZ. Using both in vitro and in vivo experimental approaches, we investigated whether addition of zinc to TMZ enhances its cytotoxicity against GBM. In vitro cell viability analysis showed that the cytotoxic activity of TMZ was substantially increased with addition of zinc and this response was accompanied by an elevation of p21, PUMA, BAX and Caspase-3 expression and a decrease in growth fraction as manifested by low ki67 and lower colony formation. Analysis of GBM as intracranial xenografts in athymic mice and administration of concurrent TMZ and zinc yielded results consistent with those of the in vitro analyses. The co-treatment resulted in significant reduction in tumor volume in TMZ/zinc treated mice relative to treatment with TMZ alone. Our results suggest that zinc may serve as a potentiator of TMZ therapy in GBM patients.

Comparison of two cytoreductive regimens for αβ-T-cell-depleted haploidentical HSCT in pediatric malignancies: Improved engraftment and outcome with TBI-based regimen

BACKGROUND

Graft manipulation using selective depletion of αβ-T cells provides a source of haploidentical hematopoietic stem cell transplantation (haplo-HSCT) enriched in effector cells. We report our experience implementing this haplo-HSCT for high-risk malignancies in pediatric patients focusing on the conditioning regimen.

PROCEDURE

We performed a retrospective study of patients who underwent T-cell receptor αβ-depleted haplo-HSCT for high-risk pediatric malignancies.

RESULTS

Eighteen patients underwent haplo-HSCT using this method. The initial reduced-toxicity chemotherapy-based conditioning regimen was given to eight patients, and resulted in a high rate of graft rejections (six of eight patients). Thus, total body irradiation (TBI) based regimen was introduced in the following 10 patients and resulted in engraftment in all patients. Neutrophil and platelet engraftment were rapid (median time to engraft, 10 days and 12 days, respectively). Significant treatment-related complications for both cohorts were all due to graft failure in patients receiving chemotherapy-based conditioning, with a treatment-related mortality rate of 17%. None of the patients developed hepatic sinusoidal-obstruction syndrome, and no grade III-IV acute graft versus host disease (GVHD) was observed. The majority of patients were free of immunosuppression in the first 100 days post-HSCT, and only two patients developed chronic GVHD. The cumulative incidence of relapse was 39%. Compared to patients conditioned with chemotherapy, patients conditioned with TBI had superior actuarial overall survival (66% vs. 37%, P = 0.05) and event-free survival (61% vs. 33%, P = 0.04).

CONCLUSIONS

A TBI-based conditioning for haplo-HSCT using αβ-T-cell depletion for malignant diseases ensured engraftment and resulted in acceptable outcomes.

Paediatric cerebral sinus vein thrombosis

The etiology and pathophysiology of cerebral sinus venous thrombosis (CSVT) in the paediatric population is still poorly understood, and the role of thrombophilic risk factors remains to be elucidated. In our multi-center case-controlled study we studied 46 patients with CSVT diagnosed from April 1996 to December 2003, consecutively referred for thrombophilia work-up. The results of thrombophilia screen were compared to 112 healthy paediatric controls. Anticoagulant therapy was applied according to treating physicians’ decisions, and all cases were prospectively followed for a median of 4.1 years. Of 46 children, 8 had CSVT diagnosed in the neonatal period and therefore were analyzed separately. The prevalence of single thrombophilia markers and combinations of thrombophilic risk factors were similar among cases and controls. Among children with CSVT co-morbid systemic illness was present in most patients at diagnosis. Seven out of 8 children with idiopathic CSVT had thrombophilic risk factors as compared to 31/38 patients with co-morbid conditions. Anticoagulation was initiated in most patients, 11/46 patients continued therapy for a total of one year or more post event. Neither clinical presentation nor initial treatment decisions were affected by presence of thrombophilic risk factors in our study group. Thrombophilia prevalence was not increased in children with CSVT as compared to controls, however thrombophilia was more frequent among children with idiopathic CSVT. Thus, those selected patients would benefit most from thrombophilia work-up, required for long-term therapy considerations.

The role of immunoglobulin prophylaxis for prevention of cytomegalovirus infection in pediatric hematopoietic stem cell transplantation recipients

BACKGROUND

Following cessation of intravenous immunoglobulin (IVIg) administration for allogeneic hematopoietic stem cell transplantation (HSCT) recipients at our unit, we observed a sharp decline in the incidence of cytomegalovirus (CMV) infection.

PROCEDURE

We conducted a retrospective study of the role of IVIg in the prevention of CMV infection in children and young adults who underwent HSCT from matched related donor.

RESULTS

We included 109 patients (IVIg+/IVIg- ratio 82/27). Median age was 8.5 years. Patients were transplanted for malignant (59.7%) and nonmalignant diseases (40.3%) with myeloablative, reduced-intensity, and nonmyeloablative conditioning in 76, 22, and 2% of the transplants, respectively. Graft sources were peripheral blood stem cells, bone marrow, and cord blood in 58.7, 39.4, and 2%, respectively. The cumulative incidence of CMV infection at 1 year after HSCT was significantly higher in the cohort that did not receive IVIg compared with the one that did (44.4% vs. 13.4%, respectively, P = 0.001). Significant risk factor for CMV infection in the cohort not receiving IVIg was conditioning with total body irradiation (TBI) (87.5% in TBI+ vs. 26.3% in TBI-, P = 0.003).

CONCLUSIONS

We conclude that children and young adults who undergo HSCT with TBI may need a preemptive regimen of anti-CMV treatment, if they do not get IVIg prophylaxis.