Audrey E. Evans

The increasing incidence of central nervous system leukemia in children. (Children's cancer study group a)

The incidence of symptomatic CNS leukemia was studied in 209 children, all of whom were entered in a cooperative study during 1963‐1964, and received the same chemotherapeutic agents. The overall incidence was 51%, and the median time for occurrence of the first episode was 9 months. The incidence was 56% in patients with acute lymphocytic leukemia (A. L. L.) and 25% in those with other forms of leukemia. CNS symptoms developed at a steady monthly rate of 3.8% for the first 24 months and then decreased to 2%. The rate for the first year was the same for all forms of leukemia; it was 4% in A. L. L. and 3.7% in the other forms combined. The overall median survival was 18 months—it was 21 months for patients with A. L. L. and 9 months for the other cell types. Life‐table analysis showed a median survival of 8 months for patients who had developed CNS leukemia and 24 months for those free of the complication. Age, sex, hematologic status, and chemotherapy regimen did not influence the incidence. We conclude that the increasing survival of children with leukemia is the chief cause for the increased incidence of CNS leukemia noted by many investigators.

Insulin-like growth factor II-mediated proliferation of human neuroblastoma.

Neuroblastoma is an embryonal tumor that typically arises in cells of the developing adrenal medulla. IGF-II mRNA is expressed at high levels in the adrenal cortex before birth but it is not detectable until after birth in the adrenal medulla. Neuroblastoma cell lines corresponding to early adrenal medullary precursors did not express IGF-II, although all three cell lines we tested were growth stimulated by IGF-II. Cell lines corresponding to more mature adrenal medullary cells expressed IGF-II, and one, SK-N-AS, grows by an IGF-II autocrine mechanism (J. Clin. Invest. 84:829-839) El-Badry, Romanus, Helman, Cooper, Rechler, and Israel. 1989. An examination of human neuroblastoma tumor tissues for IGF-II gene expression using in situ hybridization histochemistry revealed that IGF-II is expressed by tumor cells in only 5 of 21 neuroblastomas, but is detectable in cells of nonmalignant tissues including adrenal cortical cells, stromal fibroblasts, and eosinophils in all 21 tumors. These findings indicate that IGF-II may function as an autocrine growth factor for some neuroblastomas and as a paracrine growth factor for others. They suggest that the growth regulatory pathways utilized by neuroblastoma mimic those used in the precursor cell type from which individual tumors arise.

Central nervous system lesions in childhood leukemia

Central nervous system (CNS) lesions were found in 85 of 91 children with acute leukemia. Cerebral atrophy was the most common lesion, occurring in 65 percent. Atrophy was most severe in children treated with intrathecal methotrexate alone or in combination with radiation therapy, in children youngest at time of onset of leukemia, and in children in whom duration of leukemia was shortest. Longer duration was the determining factor among children who were older at onset. Lesions previously reported by other investigators, such as leptomeningeal infiltration of leukemic cells, infection, hemorrhage, degenerative grey and white matter disease and leukoencephalopathy were also seen. Central pontine myelinolysis occurred in four children.

The MYCN Enigma: Significance of MYCN Expression in Neuroblastoma

MYCN amplification strongly predicts adverse outcome of neuroblastoma. However, the significance of MYCN expression in the clinical and biological behavior of neuroblastoma has been unclear. To address this question, we first examined the expression of MYCN in combination with TrkA (a favorable prognostic indicator of neuroblastoma) in 91 primary neuroblastoma by quantitative reverse transcription-PCR and investigated the relationship among patient survival, MYCN, and TrkA expressions. Three subsets of neuroblastoma were defined based on MYCN and TrkA expression. Neuroblastoma expressing the highest level of MYCN but little TrkA were MYCN-amplified cases, which had a 5-year survival of 9.3%. Interestingly, MYCN and TrkA expression showed a linear correlation (r = 0.5664, P < 0.00005) in neuroblastoma lacking MYCN amplification, and the 5-year survival of neuroblastoma patients with low MYCN and low TrkA expressions was 63.7%, whereas those with high expression of both had a 5-year survival of 88.1% (P < 0.00005). This nonlinear distribution of disease outcome relative to MYCN expression in neuroblastoma explains why MYCN expression is not predictive of neuroblastoma disease outcome by dichotomous division of the neuroblastoma cohort. However, high-level MYCN expression is associated with favorable outcome in neuroblastoma lacking MYCN amplification. Furthermore, forced expression of MYCN significantly suppresses growth of neuroblastoma cells lacking MYCN amplification by inducing apoptosis and enhancing favorable neuroblastoma gene expression. Collectively, these data suggest that high-level MYCN expression in neuroblastoma lacking MYCN amplification results in a benign phenotype. Thus, the high MYCN expression confers the opposite biological consequence in neuroblastoma, depending on whether or not MYCN is amplified.

A study of childhood non-hodgkin's lymphoma

The pathologic and clinical features of 31 cases of childhood non‐Hodgkins lymphoma (NHL) were reviewed retrospectively using Rappaports classification and a modification of the Ann Arbor staging system. Twenty‐nine (93.5%) of the patients had diffuse and 2 (6.5%) had nodular lymphoma. Diffuse histiocytic lymphoma accounted for 10 cases (32.3%), diffuse undifferentiated for 9 (29%), and diffuse lymphocytic, poorly differentiated for 5 (16.1%). Five cases (16.1%) were unclassifiable. No cases of well‐differentiated lymphocytic or mixed cell lymphoma were found. A modified classification was attempted, which included also large basophilic cell (LBC), convoluted T‐lymphocytic (CTL), and Burkitts lymphomas. These pathologic subgroups accounted for 35.4%, 16.1%, and 6.5% of the cases, respectively. The patients were almost equally divided between clinically localized and generalized stages, and their survival was stage‐dependent. The overall survival was 32.3%; the 3‐year survival was 50% for Stages I and II, compared to 7.7% for Stages III and IV. The gastrointestinal tract was the most common site of origin. In 22% of the cases, the disease originated in extra‐lymphatic tissues. Central nervous system involvement occurred in 10 of 31 children (32%), and a leukemic picture developed in 6 of 31 (19%). The CTL lymphomas were confined to the mediastinum, whereas the LBC lymphomas arose mostly in Waldeyers ring and Peyers patches. We conclude that the extent of the disease as determined by clinical staging has prognostic significance in childhood NHL. The prognostic value of the histological classification could not be clearly established from our data.

Results of treatment of children with recurrent medulloblastoma/primitive neuroectodermal tumors with lomustine, cisplatin, and vincristine

Primitive neuroectodermal tumors/medulloblastoma (PNET/MB) are the most common posterior fossa tumors in childhood. Despite surgery and radiation therapy, 40% to 50% of children with PNET/MB will have recurrent disease. Various chemotherapeutic agents are transiently effective in recurrent PNET/MB, but long‐lasting responses are rarely attainable. To increase the rate and duration of response in children with recurrent PNET/MB, the authors treated seven patients (ages 2–18 years; median, 10 years) with lomustine (CCNU) (100 mg/m2), cisplatin (CPDD) (90 mg/m2) and vincristine (VCR) (1.5 mg/m2; maximum, 2 mg) in a 6‐week cycle for a maximum of eight cycles. Six of six evaluable patients responded to chemotherapy. Four patients had a complete response; three with complete disappearance of tumor by imaging studies; and one with eradication of extraneural disease for a median of 24 months from relapse (13–29 months). Overall disease‐free survival was 18.5 months. All six patients have subsequently died of recurrent tumor. Major toxicities consisted of reversible bone marrow suppression (six of six), high frequency hearing loss (six of six) and decreased renal function (three of six). All patients required dosage modification for toxicity. A regimen of CCNU, VCR, and CPDD is effective therapy in children with relapsed PNET/MB and can produce relatively long‐term disease control with good quality of life. Further investigation into the efficacy of this combination as adjuvant chemotherapy in newly diagnosed high‐risk PNET/MB is now being performed.

Diagnosis and Treatment of Neuroblastoma

This article focuses on signs and symptoms, diagnostic and radiological studies, differential diagnosis, and a staging system of neuroblastoma. The roles of surgical management, radiation therapy, and chemotherapy are assessed.

Effect of CEP‐751 (KT‐6587) on neuroblastoma xenografts expressing TrkB

BACKGROUND The compound CEP-751 (KT-6587), a potent and selective inhibitor of the Trk family of tyrosine kinases, has been shown to inhibit the growth of human neuroblastoma (NB) xenografts in nude mice [1]. PROCEDURE To address its mechanism of action, we studied SY5Y, a human NB cell line with no detectable Trk expression, and two subclones transfected with TrkB. The transfected clones, SY5Y (G8) and SY5Y (G12), expressed moderate and high levels, respectively, of TrkB mRNA and protein. These TrkB-expressing subclones and the parental line were then grown as xenografts in nude mice, and CEP-751 was used to inhibit TrkB tyrosine kinase activity in these xenografts. Animals were treated twice a day with CEP-751 (21 mg/kg), or with the carrier vehicle as a control. TrkB expression in the resultant tumors was examined by quantitative RT-PCR. The effect of CEP-751 on TrkB activation by BDNF was examined in G12 cells in culture by immunoprecipitation with antipan Trk antiserum, followed by Western blot analysis using antiphosphotyrosine antibodies. To determine if CEP-751 was causing apoptosis, the TUNEL assay was used. RESULTS CEP-751 had little effect on the growth of SY5Y tumors, but did slow the growth rate of the C8 and G12 tumors. The daily growth rate of the treated tumors was 0.16, 0.13, and 0.10 cm3, respectively, for the SY5Y, G8, and G12 tumors. RT PCR analysis confirmed the expression of TrkB in G8 and G12, but not in SY5Y tumors. Activation of TrkB by BDNF in G12 cells was inhibited by CEP-751 in a dose dependent fashion. The treated tumors showed marked evidence of apoptosis. CONCLUSIONS These data suggest that the effect of CEP-751 is due, at least in part, to its inhibition of TrkB kinase, and that CEP-751 may become a useful therapeutic tool for the treatment of aggressive neuroblastomas, which often express TrkB.

Results of the treatment of children with recurrent gliomas with lomustine and vincristine

Gliomas comprise over 50% of all childhood brain tumors. Treatment of recurrent childhood gliomas has been disappointing and the effectiveness of therapy has been difficult to judge because of the variable natural history of the disease. Information gathered recently has suggested that treatment with [1‐(2‐chloroethyl)‐3‐cyclohexyl‐1‐nitrosourea)] (CCNU) and vincristine (VCR) after radiotherapy is effective in prolonging survival in children with newly diagnosed anaplastic gliomas. The authors have used these same drugs—CCNU (100 mg/m2) and VCR (1.5 mg/m2 up to a maximum dose of 2 mg)—in 6‐week cycles for a maximum of eight cycles in children with recurrent gliomas. To date, 15 patients have been treated; five patients had malignant gliomas and ten low‐grade gliomas. Three children showed improvement, five had stable disease, and seven had progressive disease. Of the five patients with malignant gliomas, four progressed within two cycles of treatment and one had stable disease for 7 months on treatment and then relapsed. Seven of ten children with low‐grade gliomas benefitted from treatment and six remain in continuous remission a median of 16 months after initiation of therapy. Three of these children are off all therapy 21,30, and 30 months after treatment, respectively. Therapy was well tolerated and toxicity consisted primarily of reversible bone marrow suppression. The authors conclude that CCNU and VCR chemotherapy is effective in children with recurrent low‐grade gliomas and can result in relatively long‐term disease stabilization. In limited experience of the authors, it is not of benefit in children with recurrent anaplastic lesions.

Expression of neurotrophin receptor TrkA inhibits angiogenesis in neuroblastoma.

BACKGROUND Mechanisms regulating the expression of angiogenic factors in tumor cells are largely unknown. High expression of the neurotrophin receptor TrkA in neuroblastomas (NB) is associated with favorable prognosis, whereas TrkB is expressed on aggressive, MYCN-amplified NB. PROCEDURE To investigate the biological effects of TrkA and TrkB expression on angiogenesis in NB, we examined the expression of angiogenic factors in the human NB cell line SY5Y and its TrkA and TrkB transfectants. RESULTS In comparison to parental SY5Y cells, mRNA and protein levels of angiogenic factors were significantly reduced in SY5Y-TrkA cells, whereas SY5Y-TrkB cells did not demonstrate a significant change. Conditioned medium (CM) of parental SY5Y and SY5Y-TrkB cells induced endothelial cell proliferation, but this effect was completely absent in SY5Y-TrkA cells. TrkA expression also resulted in severely impaired tumorigenicity in a mouse xenograft model, and was associated with reduced angiogenic factor expression and less vascularization of tumors, as determined by immunohistochemistry and an in vivo Matrigel assay.