Targeted therapy: for kids, too

Innovative hypothesis-driven clinical trials have achieved major successes over the past several decades in treating children and adolescents with cancer. DNA-damaging cytotoxic agents have cured children with cancer. While the mission is not yet accomplished, chemotherapy has been validated. None of these drugs were designed specifically for a pediatric disease. Continued progress will require new strategies. Now being tested for adult cancers, these strategies include gene therapy, immunotherapy, cancer prevention, and signal transduction inhibitor (STI) therapy. Of these, the most promising is STI therapy, also known as molecular therapeutics or targeted therapy. For this therapy to succeed, components of signal transduction (i.e., candidate drug targets) must be identified, the targets relevant to cancers, and the drugs available for trial. Because STI therapy is biologically driven and because therapy will be tailored depending on the molecular profile of a specific patient's tumor, clinical pediatric oncologists will need to acquire greater understanding of signaling pathways and their therapeutic relevance. With examples drawn from pediatric oncology, the critical steps in the pre-clinical development of targeted therapy are reviewed here.     

Insight into B cell development and differentiation

The main topic of this article is B cell development and differentiation, with a special focus on the mechanisms and molecules that regulate the expression of humoral immunity. Molecular epidemiological analysis was performed on the genes responsible for the X-linked agammaglobu-linemia (XLA) phenotype of the majority of Italian patients and their distinct mutations were characterized. Mutations in Bruton's tyrosine kinase (BTK), a member of Tec Family of protein tyrosine kinases, have been found to be mainly responsible for XLA disease. The exact function of BTK in signal transduction is not yet known; thus, the specific role of BTK in receptor-dependent calcium signaling and the pro-antiapoptotic regulatory activity was addressed by transfecting RAMOS-1, a BTK-deficient human Burkitt's/B cell leukemia line with wild-type and mutant constructs. This work may provide clues about critical sites in the molecule and give support for gene therapy as a potential successful approach to XLA. Another aspect of this research is the identification and dissection of the molecular events that are likely to be directly related to the ability to express various isotypes of immunoglobulin with differing function and certain B cell immunodeficiency, mainly common variable disease and non-X-linked hyperIgM. B cell development and maturation steps in different compartments of the immune system are tracked by the analysis of cell-surface molecules and components of the signal transduction pathways, i.e. CD40, CD30, CD27, CD38, CD22 and CD24. A few components involved in B cell development, maturation and differentiation and their specific functional role are at least partially known, but these are far from fitting into an understandable pathway at present.     

Insight into B cell development and differentiation

The main topic of this article is B cell development and differentiation, with a special focus on the mechanisms and molecules that regulate the expression of humoral immunity. Molecular epidemiological analysis was performed on the genes responsible for the X-linked agammaglobulinemia (XLA) phenotype of the majority of Italian patients and their distinct mutations were characterized. Mutations in Bruton's tyrosine kinase (BTK), a member of Tec Family of protein tyrosine kinases, have been found to be mainly responsible for XLA disease. The exact function of BTK in signal transduction is not yet known; thus, the specific role of BTK in receptor-dependent calcium signaling and the pro-antiapoptotic regulatory activity was addressed by transfecting RAMOS-1, a BTK-deficient human Burkitt's/B cell leukemia line with wild-type and mutant constructs. This work may provide clues about critical sites in the molecule and give support for gene therapy as a potential successful approach to XLA. Another aspect of this research is the identification and dissection of the molecular events that are likely to be directly related to the ability to express various isotypes of immunoglobulin with differing function and certain B cell immunodeficiency, mainly common variable disease and non-X-linked hyperIgM. B cell development and maturation steps in different compartments of the immune system are tracked by the analysis of cell-surface molecules and components of the signal transduction pathways, i.e. CD40, CD30, CD27, CD38, CD22 and CD24. A few components involved in B cell development, maturation and differentiation and their specific functional role are at least partially known, but these are far from fitting into an understandable pathway at present.     

New targets and targeted drugs for the treatment of cancer: an outlook to pediatric oncology

Novel drugs and treatment modalities are urgently needed to further improve survival of children with cancer. In medical oncology, an increased understanding of the molecular basis of cancer is driving the development of new drugs that target relevant signaling pathways in cancer cells and tumor microenvironment. Small-molecule modulators of signal transduction and monoclonal antibodies against various cellular targets have been approved in adult cancers in recent years. These drugs are now starting to be considered for the use in children. Despite the biological differences between adult and pediatric cancers, common cellular pathways have emerged from experimental research. Thus, insights into clinical experience with molecular targeted drugs in adults may help to accelerate progress in pediatric oncology. Here, the authors review molecules and pathways for which drugs are approved for adult cancer treatment and provide links to existing and potential applications in pediatric oncology.     

Pharmacogenetics and pharmacogenomics.

This article introduces pharmacogenetics and pharmacogenomics in the context of pharmacotherapy in the pediatric ICU setting. As an independent discipline (if it can be considered as such), pediatric or developmental pharmacogenetics is essentially at a neonatal stage. Available pharmacokinetic data derived from studies of drugs that are largely dependent on a single CYP pathway for their elimination provide initial assessments of the developmental profile of that particular CYP isoform. Essentially then, pharmacogenetics in a pediatric context refers to the changes in phenotype that occur as a child grows and develops. Furthermore, the apparent drug biotransformation "phenotype" may be influenced by disease (infection), environmental factors (diet and environmental contaminants) and concurrent medications; however, drug response is a function of the complex interplay among genes involved in drug transport, drug biotransformation, receptors, and signal transduction processes, among others. Therefore, optimization of pediatric pharmacotherapy necessarily requires that developmental changes in each of these areas and not just drug biotransformation be investigated thoroughly before the promise of pharmacogenetics and pharmacogenomics for rational therapeutics can be realized in children.     

Immunosuppression for pediatric cardiac transplantation in the modern era

With the advent of the T cell activation inhibitors such as cyclosporine, heart transplant success rates for pediatric patients have improved to the point that the initially restricted ages and indications have expanded considerably. Currently the half-life (50% still alive) for children transplanted in the early 1980s is approximately 12-14 years. Decades-long survival seems likely. Components and functions of the immune system are na?ve and change during postnatal development. Maturation occurs not only in the first years of life, but well through adolescence and even into adult life. These age-dependent changes within the immune system greatly complicate any attempt to assess immune implications for the use of immunosuppression in children. Since the introduction of cyclosporine, immunosuppression regimens have been virtually unchanged through the 1990s. Recently, there have been significant new immune pharmacological agents which are now commercially available, or still in investigational stages of development. The new maintenance immunosuppressive drugs are either inhibitors of de novo synthesis of nucleotides (purines or pyrimidines), or are immunophilin-binding drugs that inhibit signal transduction in lymphocytes. The newer inhibitors of de novo nucleotide synthesis include mycophenolate mofetil, mizoribine, brequinar and leflunomide. The immunophilin-binding drugs are cyclosporine, tacrolimus and rapamycin. Antibody preparations such as ATG, ATGAM and OKT3, as well as the newer biological agents, which specifically bind to the IL-2 receptor, basiliximab and daclizumab, are discussed. The potential for biologicals which inhibit co-stimulation are also discussed. There may be dramatic changes in protocols used clinically as a result of these new agents over the next decade. The increasing understanding of the alloimmune response as well as the clinical use of these newer drugs promise even better long-term results.     

A new case of autosomal recessive agammaglobulinaemia with impaired pre-B cell differentiation due to a large deletion of the IGH locus

Males with X-linked agammaglobulinaemia (XLA) due to mutations in the Bruton tyrosine kinase gene constitute the major group of congenital hypogammaglobulinaemia with absence of peripheral B cells. In these cases, blockages between the pro-B and pre-B cell stage in the bone marrow are found. The remaining male and female cases clinically similar to XLA represent a genotypically heterogeneous group of diseases. In these patients, various autosomal recessive disorders have been identified such as mutations affecting IGHM, CD79A, IGLL1 genes involved in the composition of the pre-B cell receptor (pre-BCR) or the BLNK gene implicated in pre-BCR signal transduction. In this paper, we report on a young female patient characterised by a severe non-XLA agammaglobulinaemia that represents a new case of Igmu defect. We show that the B cell blockage at the pro-B to pre-B cell transition is due to a large homologous deletion in the IGH locus encompassing the IGHM gene leading to the inability to form a functional pre-BCR. The deletion extends from the beginning of the diversity (D) region to the IGHG2 gene, with all JH segments and IGHM, IGHD, IGHG3 and IGHG1 genes missing. CONCLUSION: alteration in Igmu expression seems to be relatively frequent and could account for most of the reported cases of autosomal recessive agammaglobulinaemia.     

Role of physical exercise in children and adolescents with diabetes mellitus

During the past 50 years several studies have underlined the central role of physical exercise in the management of patients with both type 1 and type 2 diabetes mellitus. The numerous benefits described in normal individuals who practise regular exercise have also been demonstrated in patients with diabetes who obtained significant physical and psychological advantages for the care of the underlying disease. Despite physical and psychological benefits, the occurrence of acute complications and some important effects on diabetes-related vascular complications may often discourage patients from participation in sports activities. However, even though adverse events may occur, exercise is still judged one of the most important components in the treatment of patients with diabetes. Thus, children, adolescents and young adults with diabetes must be educated on the metabolic changes occurring during physical activity in order to be able to acquire the ability to individually modulate their diet and insulin therapy before and after exercise. Appropriate education may allow a proper and correct approach to physical exercise.     

EXCITING NEW TREATMENT APPROACHES FOR PATHYPHYSIOLOGIC MECHANISMS OF SICKLE CELL DISEASE

During the past several decades, our understanding of the complex pathophysiology of vasoocclusion associated with sickle cell disease has improved greatly. Interaction of genes, hemoglobin molecules, red cell membrane and metabolic changes, cell-cell interactions and cell-plasma interactions, red cell adhesion to vascular endothelium, activation of coagulation, and vascular reactivity play a role in vaso occlusion. Penicillin prophylaxis of pneumococcal infections and appropriate use of blood transfusions and other supportive measures improved survival of sickle cell patients. Hydroxyurea made a major impact on sickle cell therapy when it was shown to decrease acute painful episodes, acute chest syndrome, and the need for blood transfusion in adults. Significant experience in the use of hydroxyurea has been accumulated in older children. The benefits and risks of hydroxyurea for younger children and long-term risks in all patients will be evaluated in future investigations. Other promising therapies include butyrate compounds, clotrimazole, magnesium supplementation, poloxamer 188, antiadhesion agents, anticoagulant approaches, and nitric oxide. Hemopoietic transplantation remains the only curative therapy. However, several transgenic mouse models are available for studies of gene therapy or other treatment approaches on biochemical, cellular, and pathologic effects of mutant genes.     

The action of antitumor agents: a double-edged sword?

Although cytotoxic immunosuppressive agents play an unquestionably useful role in treating many neoplastic and non-neoplastic disorders, there is accumulating evidence that the toxicity associated with their use is considerable. The therapeutic successes obtained with antitumor agents have led to increases in the life span of cancer patients, but have also provided the opportunity for this toxicity to become manifest. A search of the available literature was carried out, with emphasis on cases in which a malignancy developed in patients following chemotherapy for either neoplastic or non-neoplastic (e.g., renal transplantation, psoriasis) conditions; particular focus was given to the incidence of acute myelogenous leukemia in various groups of Hodgkin's disease and multiple myeloma patients. That patients with nonmalignant conditions treated with cytotoxic immunosuppressive agents are also at increased risk of developing a malignancy raises the possibility that these agents may have oncogenic potential. Therefore, one may be faced with the paradox that the patients benefiting most from chemotherapy may be at highest risk of suffering its consequences.     

What’s new in the neuro-cardio-facial-cutaneous syndromes?

The RAS-MAPKinase pathway is a signal transduction cascade which has been studied extensively during the last decades for its role in human oncogenesis. Activation of this cascade is controlled by cycling of the RAS protein between an inactive and an active state and by phosphorylation of downstream proteins. The signalling cascade regulates cell proliferation, differentiation and survival. Disturbed RAS signalling in malignancies is caused by acquired somatic mutations in RAS genes or other components of this pathway. Recently, germline mutations in genes coding for different components of the RAS signalling cascade have been recognized as the cause of several phenotypically overlapping disorders, recently referred to as the neuro-cardio-facial-cutaneous syndromes. Neurofibromatosis type 1, Noonan, LEOPARD, Costello and cardiofaciocutaneous syndromes all present with variable degrees of psychomotor delay, congenital heart defects, facial dysmorphism, short stature, skin abnormalities and a predisposition for malignancy. These findings point to important roles for this evolutionary conserved pathway in oncogenesis, development, cognition and growth. Conclusion: it has become obvious in recent years that the neuro-cardio-facial-cutaneous syndromes all share a common genetic and pathophysiologic basis. Dysregulation of the RAS-MAPKinase pathway is caused by germline mutations in genes involved in this pathway. Undoubtedly more genes causing related syndromes will be discovered in the near future since there are still a substantial number of genes in the pathway that are not yet associated with a known syndrome. Human genes and proteins are written in capital letters; murine genes and proteins in small letters. Genes are written in italic, proteins are written straight.     

小分子靶向药JAK抑制剂在儿童风湿免疫性疾病中的应用

Janus激酶（Januskinases,JAK）抑制剂是一种小分子靶向药,可以抑制相关炎症因子信号传导通路而具备抗炎作用,目前已有多种JAK抑制剂上市用于包括风湿免疫性疾病在内的各系统疾病。作为新型靶向合成类改善病情抗风湿药物,JAK抑制剂已上市用于甲氨喋呤应答不足或不耐受的成人类风湿性关节炎,且在成人强直性脊柱炎、溃疡性结肠炎、皮肌炎、血管炎等多种风湿性疾病中均有应用,但在儿童风湿免疫性疾病中仍缺乏大规模临床证据。JAK抑制剂治疗幼年特发性关节炎已进入Ⅲ期临床试验,在治疗幼年型皮肌炎、系统性红斑狼疮、多发性大动脉炎也有报道,且是相关自身炎症性疾病的靶向药物。因此,JAK抑制剂在儿童风湿免疫性疾病中的应用具有广泛前景。     

Successful allogeneic unrelated bone marrow transplantation using reduced-intensity conditioning for the treatment of X-linked adrenoleukodystrophy in a one-yr-old boy

Abstract:  The childhood cerebral form of X-linked ALD is a demyelinating disorder of the central nervous system, which rapidly leads to total disability and death. Allogeneic stem cell transplantation benefits patients who show early evidence of the demyelination. We report here a one-yr-old boy with ALD who received HLA-matched unrelated BMT in an early stage of the disease after careful planning and observation since his birth. BMT was performed when MRI began to show slight signal intensity changes in the white matter of the brain. Pretransplant conditioning consisted of fludarabine, l -PAM and TBI (2 Gy). GVHD prophylaxis consisted of cyclosporine A and short-course methotrexate. The patient showed an uneventful BMT course with fast and stable engraftment. Following BMT, the plasma levels of VLCFA decreased gradually and MRI changes improved. The patient did not have any evidence of further neurological deterioration 22 months following the transplant. Although this is still a short follow-up, it has been shown that BMT should be considered when a child has a biochemical diagnosis and MRI findings of ALD without any neurological signs. RIST should be considered as a pretransplant conditioning for ALD.     

细胞间黏附分子-1在中枢神经系统疾病中的表达和调控

细胞间黏附分子-1(ICAM-1)分布于体内多种组织细胞表面,是具有广泛生物学活性的一种黏附因子,在炎症与免疫应答、信号转导、组织修复等多种生理与病理过程中起重要作用。现就ICAM-1在体内的表达与调控,以及其在某些中枢神经系统疾病发病中的作用作一综述。     

癫(癎)持续状态与脑损伤机制研究进展

癫(癎)持续状态(SE)的发病机制与脑损伤密切相关,已有试验证实钙/钙调素依赖性蛋白激酶2活性改变、氧化应激、神经免疫-内分泌网络失衡等因素不仅参与癫(癎)持续状态的机制,且能作为始动因素,参与神经元损伤.SE后脑组织急性缺血、缺氧,糖利用减少,神经元过度兴奋,N-甲基-D-天冬氨酸(NMDA)和非NMDA受体的活化,大量阳离子内流,除导致神经细胞急性坏死,同时还启动细胞凋亡相关基因的表达,引起细胞内的凋亡酶级联反应,导致细胞凋亡.目前研究发现死亡受体活化、线粒体损伤及内质网应激通路均介导SE后神经元凋亡信号的传导.

Abstract：

The pathogenesis of status epilepticus is closely associated with brain injury. Some animals experiments have proved that the activity of calcium / calmodulin-dependent protein kinase 2 ( CaM kinase Ⅱ ) ,oxidative stress, and the imbalance of nervous immune-endocrine factors are not only involved in the mechanisms of status epilepticus, but also act as the initial factor in neuronal injury. The pathophysiological changes after SE,such as acute brain ischemia, hypoxia and the reduced glucose utilization, over-excited neurons, N-methyl-Daspartate (NMDA) and non-NMDA receptor activated, a large amount of cation influx, can give rise to acute necrosis of neurons, also initiate the expression of apoptotic genes, at last leading to apoptosis by cell apoptotic enzymes cascade reaction. Studies have found that the pathway of death receptor activation, mitochondrial damage and endoplasmic reticulum stress mediated the neuronal apoptotic signal transduction after SE.     

The cytogenetics of childhood leukemia: clinical and biologic implications

Cytogenetic studies have revealed a broad spectrum of abnormalities in the chromosomal make-up of human leukemic cells. These abnormalities are acquired during the process of malignant transformation within the neoplastic clone and reflect the genetic lesions and ablations that have occurred. Because cytogenetic abnormalities are tightly linked to the molecular events that lead to leukemogenesis, it is not surprising that these features correlate with immunophenotypic and morphologic features of the leukemic cells, as well as with the clinical characteristics of children at diagnosis and their responsiveness to therapy. Molecular analysis of the disordered structure or disrupted regulation of genes located at critical chromosomal breakpoints in leukemic cells should continue to provide important insight into normal and aberrant hematopoietic cell function.     

Educational paper

Although cure rates for children with cancer are approximately 70%, improvements in cure rates have slowed in the past decade, likely due to our inability to further improve outcome using currently available drugs. Novel drug approaches are needed for children with difficult-to-treat malignancies, such as stage IV neuroblastoma, sarcomas, brain tumors, and relapsed leukemia. Several novel agents show promise for improving outcome in patients with either high risk or recurrent disease. For leukemia, inhibitors of cell cycle progression, such as clofarabine and nelarabine, have shown great promise in their ability to increase treatment efficacy in high-risk disease. Targeted agents such as tyrosine kinase inhibitors, DNA binding compounds (trabectedin), and monoclonal antibodies (GD2 inhibitors for neuroblastoma and anti-CD22 antibodies for pre-B acute lymphocytic leukemia (ALL)) also show promise for future treatment. Extensive reviews of each of these agents are presented elsewhere; this article provides an overview of molecular agents at different stages of FDA/EMA approval; those that are currently approved for use in children, currently approved for use in adults, as well as those that show promise in early clinical trial testing, or are supported by strong preclinical data.