[THE BENEFIT OF MOLECULAR ANALYSIS USING NEXT GENERATION SEQUENCING METHODS IN PEDIATRIC "HARD TO TREAT" TUMORS - EXPERIENCE IN A TERTIARY MEDICAL CENTER].

INTRODUCTION: While survival rates among children with cancer are high, a significant proportion of the solid tumors are considered as hard to treat (HTT). Next generation sequencing (NGS) offers the ability to detect molecular changes in tumors. Its implementation may allow usage of targeted therapy for tumors that fail to respond to acceptable oncological treatment. Furthermore, these therapies are characterized by milder side effects than chemotherapy. NGS may also aid in establishing pathological diagnoses and occasionally, identifying cancer-predisposition syndromes. However, the benefit of NGS in the pediatric population is not clear. AIMS: Evaluating the benefit of NGS in children with 'HTT' Tumors. METHODS: A retrospective study of the usage of NGS in pediatric 'HTT' in the Department of Pediatric Hemato-Oncology at the Hadassah Medical Center. Patients' demographic and clinical characteristics, molecular changes in tumor, their influence on medical decisions and disease course - were all documented. RESULTS: Forty-seven NGS tests from 'HTT' tumors were completed between January 2018 to August 2020. The results of these tests dictated medical decisions in 18 cases (38.3%) while it proved utility in 10 cases (21.3%). Clinical response to targeted therapy, clarification of diagnosis and identification of germline changes were documented in 3 (6.4%), 4 (8.5%) and 3 (6.4%) cases, respectively. CONCLUSIONS: The usage of NGS may benefit children with 'HTT' and tumors with difficult diagnoses and in some cases may be life-saving. DISCUSSION: Cost-benefit considerations presumably prevent the assimilation of NGS tests in the standard care of pediatric oncology. It is possible that the current results will strengthen the more accurate usage of theses genomic techniques in children with 'HTT'.

Invasive Fungal Infections in Children with Acute Leukemia: Epidemiology, Risk Factors, and Outcome.

Invasive fungal infections (IFI) cause morbidity and mortality in children with acute leukemia (AL). We retrospectively collected data on febrile neutropenic episodes (FNE) in AL children (2016-2021) and assessed factors associated with proven/probable IFI. Ninety-three children developed 339 FNE. Seventeen (18.3%) children developed 19 proven/probable IFI (11 yeast; eight molds). The proven/probable yeast IFI rate was 6/52 (11.5%) in children who belong to the high risk for IFI category (HR-IFI-AL: high-risk acute lymphocytic leukemia (ALL), acute myeloid leukemia, relapse); and 5/41 (12.2%) in the non-HR-IFI-AL category (standard/intermediate risk ALL). The proven/probable mold IFI rate was 7/52 (13.5%) in HR-IFI-AL children and 1/41 (2.4%) in the non-HR-IFI-AL category. In the multivariable analysis, underlying genetic syndrome, oral mucositis, and older age were significantly associated with proven/probable IFI, while a longer time since AL diagnosis was protective. Two of 13 (15.4%) HR-IFI-AL children died because of IFI. The elevated risks of proven/probable mold IFI and the associated mortality in HR-IFI-AL children, and high risk of invasive candidiasis in the non-HR-IFI-AL group, emphasize the need for the close monitoring of local epidemiology and the adjustment of practices accordingly.

Improving pediatric idiopathic intracranial hypertension care: a retrospective cohort study.

To describe the clinical course and prognosis of pediatric idiopathic intracranial hypertension (IIH) and examine the preferred management setting. IIH is characterized by increased intracranial pressure and is often associated with headaches and visual complaints. IIH is a preventable cause of vision loss in children. Hence, a rapid diagnosis followed by prompt treatment and follow-up is essential. However, standardization of the management of IIH in the pediatric population is not well established. Computerized medical charts of all 82 pediatric (< 18 years) patients diagnosed with IIH between 2007 and 2018 in the metropolitan area of Jerusalem were reviewed. Comparison was made between children followed in a multidisciplinary clinic in tertiary centers and those followed elsewhere. Detailed demographic and clinical data, as well as data regarding the follow-up setting and clinical course of the disease, were collected and analyzed. Recurrent IIH-related hospital returns were selected as a measurable marker for the uncontrolled disease. Recurrent IIH-related hospital return rate was significantly lower and occurred later among children followed by multidisciplinary teams compared to individual experts. Follow-up in multidisciplinary clinics improve the quality of life, and financial burden and may prevent permanent visual impairment in children with IIH.

Neonatal thrombotic microangiopathy secondary to factor I variant with Hirschsprung disease.

Neonatal thrombotic microangiopathy (TMA) is a rare and severe disease characterized by a triad of non-immune hemolytic anemia, thrombocytopenia, and organ dysfunction in neonates. We describe herein an early-term infant who underwent hemicolectomy at 4 days of age due to intestinal perforation. Following surgery, the patient had recurrent bouts of vomiting and abdominal distention, together with acute kidney injury, non-immune hemolytic anemia, and severe thrombocytopenia. Low complement levels raised the possibility of complement-mediated neonatal TMA. Finally, genetic tests identified a heterozygous mutation in the complement factor I gene. Anti-C5 monoclonal antibody therapy led to complete cessation of the hematological and renal manifestations, but symptoms of intestinal obstruction recurred. Intestinal biopsy demonstrated aganglionosis, compatible with Hirschsprung disease. This presentation is the first known case of neonatal complement-mediated TMA associated with Hirschsprung disease. Moreover, it highlights the importance of considering a diagnosis of TMA in cases of atypical neonatal infectious presentation.

Dynamic genotype-selective "phenotypic switching" of CGRP expression contributes to differential neuropathic pain phenotype.

Using a genetic model we demonstrate the role played by "phenotypic switching" of calcitonin gene related peptide (CGRP) expression in axotomized large Aß afferents in the development of neuropathic pain behavior in rats. After nerve injury both substance P and CGRP are upregulated in Aß afferents in the corresponding DRGs. It has been proposed that intraspinal release of these neurotransmitters upon gentle stroking of skin drives ascending pain signaling pathways resulting in tactile allodynia. We reported previously that in rat lines genetically selected for high (HA) vs. low (LA) pain phenotype, SP is upregulated equally in both strains, but that CGRP is upregulated exclusively in the pain prone HA line (Nitzan-Luques et al., 2011). This implicates CGRP as the principal driver of tactile allodynia. Here we confirm this conclusion by showing: 1) that the time of emergence of CGRP-IR in DRG Aß neurons and their central terminals in HA rats matches that of pain behavior, 2) that following spinal nerve lesion (SNL) selective activation of low threshold afferents indeed drives postsynaptic pain-signaling neurons and induces central sensitization in HA rats, as monitored using c-Fos as a marker. These changes are much less prominent in LA rats, 3) that intrathecal (i.t.) administration of CGRP induces tactile allodynia in naïve rats and 4) that i.t. administration of the CGRP-receptor antagonist BIBN4096BS (Olcegepant) attenuates SNL-evoked tactile allodynia, without blocking baseline nociception. Together, these observations support the hypothesis that genotype-selective phenotypic switching of CGRP expression in Aß afferents following nerve injury is a fundamental mechanism of neuropathic tactile allodynia.

Genotype-selective phenotypic switch in primary afferent neurons contributes to neuropathic pain.

Pain is normally mediated by nociceptive Aδ and C fibers, while Aß fibers signal touch. However, after nerve injury, Aß fibers may signal pain. Using a genetic model, we tested the hypothesis that phenotypic switching in neurotransmitters expressed by Aß afferents might account for heritable differences in neuropathic pain behavior. The study examined selection-line rats in which one line, high autotomy (HA), shows higher levels of spontaneous pain in the neuroma neuropathy model, and of tactile allodynia in the spinal nerve ligation (SNL) model, than the companion low autotomy (LA) line. Changes in calcitonin gene-related peptide (CGRP) and Substance P expression were evaluated immunohistochemically in L4 and L5 dorsal root ganglia 7 days after SNL surgery. Expression of CGRP was decreased in axotomized small- and medium-diameter neurons in both rat lines. However, in HA but not in LA rats, there was a tenfold increase in CGRP immunoreactivity (CGRP-IR) in large-diameter neurons. Corresponding changes in CGRP-IR in axon terminals in the nucleus gracilis were also seen. Finally, there were indications of enhanced CGRP neurotransmission in deep laminae of the dorsal horn. Substance P immunoreactivity was also upregulated in large-diameter neurons, but this change was similar in the 2 lines. Our findings suggest that phenotypic switching contributes to the heritable difference in pain behavior in HA vs LA rats. Specifically, we propose that in HA rats, but less so in LA rats, injured, spontaneously active Aß afferents both directly drive CGRP-sensitive central nervous system pain-signaling neurons and also trigger and maintain central sensitization, hence generating spontaneous pain and tactile allodynia.