Long-term results of the children's cancer group studies for childhood acute lymphoblastic leukemia 1983-2002: a Children's Oncology Group Report

The Children's Cancer Group enrolled 13 298 young people age <21 years on 1 of 16 protocols between 1983 and 2002. Outcomes were examined in three time periods, 1983-1988, 1989-1995, 1996-2002. Over the three intervals, 10-year event-free survival (EFS) for Rome/National Cancer Institute standard risk (SR) and higher risk (HR) B-precursor patients was 68 and 58%, 77 and 63%, and 78 and 67%, respectively, whereas for SR and HR T-cell patients, EFS was 65 and 56%, 78 and 68%, and 70 and 72%, respectively. Five-year EFS for infants was 36, 38, and 43%, respectively. Seminal randomized studies led to a number of important findings. Stronger post-induction intensification improved outcome for both SR and HR patients. With improved systemic therapy, additional intrathecal (IT) methotrexate effectively replaced cranial radiation. For SR patients receiving three-drug induction, iso-toxic substitution of dexamethasone for prednisone improved EFS. Pegylated asparaginase safely and effectively replaced native asparaginase. Thus, rational therapy modifications yielded better outcomes for both SR and HR patients. These trials provide the platforms for current Children's Oncology Group trials.

Staged informed consent for a randomized clinical trial in childhood leukemia: impact on the consent process

BACKGROUND

Children Cancer Group (CCG) 1991 is the first childhood acute lymphoblastic leukemia trial within CCG that allowed the utilization of a staged approach to the consent process.

METHODS

One hundred and forty subjects participated in the Project on Informed Consent which compared the primary outcome measures in the consent process of patients enrolled in CCG-1991 with those enrolled in other CCG leukemia studies.

RESULTS

The parents' trust scores were higher for the CCG-1991 compared with other protocols. Eighty percent of parents enrolled in CCG-1991 understood the distinction between the randomized clinical trial and the standard treatment arm, compared with 62.5% in the other studies, P = 0.05. Multiple other outcome measures suggested a positive impact from staged informed consent.

CONCLUSIONS

Our results suggest that a consent process with a staged approach can help investigators obtain a more truly informed consent. Future research is needed to confirm the benefits of the staged approach to the informed consent process.

Long-term treatment of refractory thrombocytopenia in a patient with Wiskott-Aldrich syndrome with vincristine, immunoglobulin, and methylprednisolone

We report a child with Wiskott-Aldrich syndrome with severe, refractory, symptomatic thrombocytopenia who achieved an excellent response to combination therapy with vincristine 1.5 mg/m(2) x 1 day, intravenous immunoglobulin 1 g/kg x 3 days, and methylprednisolone 25 mg/kg x 3 days (VIM) for 7 years after failing multiple treatments. He did not have a histocompatible donor for bone marrow transplantation. When the patient ceased to respond to this regimen, he was rescued with pulse dexamethasone. Vincristine, immunoglobulin, and methylprednisolone might serve as a novel treatment option for the patient with refractory thrombocytopenia. Our patient had a sustained remission of symptomatic thrombocytopenia without toxicity. Furthermore, pulse dexamethasone might be an alternative treatment option to which patients with Wiskott-Aldrich syndrome may respond.

Mig, the monokine induced by interferon-gamma, promotes tumor necrosis in vivo

Mig, the monokine induced by interferon-gamma, is a CXC chemokine active as a chemoattractant for activated T cells. Mig is related functionally to interferon-inducible protein 10 (IP-10), with which it shares a receptor, CXCR3. Previously, IP-10 was found to have antitumor activity in vivo. In the present study, murine Mig RNA was found to be expressed at higher levels in regressing Burkitt's lymphoma tumors established in nude mice compared with progressively growing tumors. Daily inoculations of purified recombinant human Mig into Burkitt's tumors growing subcutaneously in nude mice consistently caused tumor necrosis associated with extensive vascular damage. These effects were indistinguishable from those produced by intratumor inoculations of Burkitt's tumors with IP-10. These results support the notion that Mig, like IP-10, has antitumor activity in vivo.

Interleukin-15 promotes angiogenesis in vivo

IL-15, a cytokine with biological functions on cells of lymphoid lineage similar to those of IL-2, mediates its activities through the beta and gamma chains of the IL-2/15R and its own alpha chain. Unlike IL-2, IL-15 also binds to endothelial cells with high affinity. We report here that IL-15 is a stimulator of angiogenesis in vivo. When injected subcutaneously into nude mice, IL-15 consistently induced neovascularization of Matrigel plugs. Endothelial cells were found to express the IL-15R alpha chain and the IL-2/15R beta and common gamma chains. IL-15 induced the rapid tyrosine phosphorylation of proteins in endothelial cells, but did not stimulate endothelial cell proliferation in vitro. These findings document a previously unrecognized biological property of IL-15 and emphasize the role of IL-15 as an important mediator outside the immune system.

Interferon-inducible protein-10 identified as a mediator of tumor necrosis in vivo

Human Burkitt lymphoma cell lines give rise to progressively growing subcutaneous tumors in athymic mice. These tumors are induced to regress by inoculation of Epstein-Barr virus-immortalized normal human lymphocytes. In the present study, analysis of profiles of murine cytokine/chemokine gene expression in Burkitt tumor tissues excised from the nude mice showed that expression of the murine alpha-chemokine interferon-inducible protein-10 (IP-10) was higher in the regressing than in the progressive Burkitt tumors. We tested the effects of IP-10 on Burkitt tumor growth in nude mice. Inoculation of established Burkitt tumors either with crude preparations of murine IP-10 or with purified human IP-10 caused visible tumor necrosis in a proportion of the animals, although no complete tumor regressions were observed. Constitutive expression of murine IP-10 in Burkitt cells reduced their ability to grow as subcutaneous tumors, and caused visible tumor necrosis in a proportion of the animals. Histologically, IP-10-treated and IP-10-expressing Burkitt tumors had widespread evidence of tumor tissue necrosis and of capillary damage, including intimal thickening and vascular thrombosis. Thus, IP-10 is an antitumor agent that promotes damage in established tumor vasculature and causes tissue necrosis in human Burkitt lymphomas established subcutaneously in athymic mice.

A role for the interferon-inducible protein 10 in inhibition of angiogenesis by interleukin-12

We have developed a nude mouse model in which tumor regression is reproducibly induced by coinjection with or intratumor inoculation of EBV-immortalized B cells. A wide spectrum of tumor-derived human cell lines can be established as subcutaneous tumors in sublethally irradiated athymic mice. Most of these tumors are induced to regress by human B cells immortalized with EBV. The tumor regression process is characterized by superficial necrosis and scarring that progressively extends itself to involve all or most of the tumor. Microscopically, tumor regression is characterized by tumor tissue necrosis, evidence of vascular damage with intimal thickening and capillary thrombosis, and macrophage, but not lymphocyte or neutrophil, infiltration. Profiles of cytokine expression differed between progressive and regressive Burkitt's tumors in that regressive tumors expressed larger levels of TNF-alpha, IL-6, IFN-gamma, IP-10, Mig, and IL-12 p35, but not other chemokines/cytokines. IP-10 and IL-12 were found to act as potent inhibitors of angiogenesis in vivo. IL-12 is an inducer of IFN-gamma and indirectly of IP-10, an IFN-gamma-inducible protein, raising the possibility that the antiangiogenic effect of IL-12 is mediated by IP-10. Previous studies have demonstrated that IL-12 has potent antitumor activity in vivo. Much of this activity was dependent on the presence of IFN-gamma and of immune T cells. The observation, made in our studies, that IP-10 is an inhibitor of angiogenesis raises the possibility that IP-10 might contribute to the antitumor effects of IL-12 by inhibiting angiogenesis. Inhibition of angiogenesis by IP-10 and IL-12 is T-cell independent, suggesting that IL-12 targets at least two compartments, T cells and capillaries, each capable of mediating antitumor effects.

Inhibition of angiogenesis by interleukin-12 is mediated by the interferon-inducible protein 10

Interleukin 12 (IL-12), a multifunctional cytokine produced by macrophages and B-cell lines, induces interferon-gamma (IFN-gamma) production, stimulates growth of both T and natural killer cells, promotes Th1-type helper T-cell responses, and inhibits neovascularization. Because the human interferon-inducible protein 10 (IP-10) can also inhibit neovascularization, we tested whether IP-10, induced by IL-12 through the intermediate IFN-gamma, might be a mediator of IL-12 angiogenesis inhibition. We report here that murine IL-12 profoundly inhibited basic fibroblast growth factor (bFGF)-induced Matrigel neovascularization in vivo, and that this effect of IL-12 was neutralized by systemic administration of antibodies to either murine IFN-gamma or IP-10. Murine IL-12 induced murine IP-10 expression in mouse splenocytes, and human IFN-gamma induced human IP-10 expression in purified human endothelial cells, suggesting that IL-12 can induce IP-10 expression in certain cells. These results document the important role of IP-10 as a mediator of angiogenesis inhibition by IL-12, and raise the possibility that IP-10 may also contribute to the antitumor effect of IL-12.

Regression of experimental human leukemias and solid tumors induced by Epstein-Barr virus-immortalized B cells

We previously have reported on an experimental athymic mouse model in which regression of human Burkitt's lymphoma is induced by either coinjection with or intratumor inoculation of Epstein-Barr virus (EBV)-immortalized human B cells. In the current study, we were interested in determining whether the powerful antitumor effects of EBV-immortalized B cells could be effective against a variety of human tumors grown in athymic mice, including acute lymphocytic leukemia, malignant melanoma, acute promyelocytic leukemia, neuroblastoma, lung carcinoma, colon adenocarcinoma, Wilms tumor, Hodgkin's lymphoma, rhabdomyosarcoma and breast adenocarcinoma. We report here the results of experiments in nude mice that demonstrated the potent antitumor effect of EBV-immortalized B cells against human tumors derived from a variety of different tissues.

Human interferon-inducible protein 10 is a potent inhibitor of angiogenesis in vivo

Human interferon-inducible protein 10 (IP-10), a member of the alpha chemokine family, inhibits bone marrow colony formation, has antitumor activity in vivo, is chemoattractant for human monocytes and T cells, and promotes T cell adhesion to endothelial cells. Here we report that IP-10 is a potent inhibitor of angiogenesis in vivo. IP-10 profoundly inhibited basic fibroblast growth factor-induced neovascularization of Matrigel (prepared by H. K. Kleinman) injected subcutaneously into athymic mice. In addition, IP-10, in a dose-dependent fashion, suppressed endothelial cell differentiation into tubular capillary structures in vitro. IP-10 had no effect on endothelial cell growth, attachment, and migration as assayed in vitro. These results document an important biological property of IP-10 and raise the possibility that IP-10 may participate in the regulation of angiogenesis during inflammation and tumorigenesis.

Epstein-Barr virus as an agent of haematological disease

Epstein-Barr virus (EBV) encodes genes that permit its persistence in human B lymphocytes and genes that ensure its replication in epithelial cells. Immune restraints on the virus are usually so effective that most EBV infections are limited to a minute fraction of B lymphocytes and of epithelial cells. As a result, most EBV infections are never symptomatic. Occasionally, the virus causes disease, often with the cooperation of the immune system or other less characterized cofactors. Infectious mononucleosis, a generally self-limited lymphoproliferative illness common in adolescents and young adults, is due to primary EBV infection and to the brisk cellular immune response it elicits. Lymphoproliferative disorders of EBV-infected B cells arise almost exclusively when cellular immunity is grossly compromised. EBV-positive Burkitt's lymphoma contain a translocated and deregulated c-myc oncogene and EBV-positive non-Hodgkin's lymphomas are characterized by the presence of Reed-Sternberg's and Hodgkin's cells, features that have not been directly linked to EBV. Many recent observations, however, including evidence that virus infection precedes malignant transformation and is often associated with a characteristic pattern of viral gene expression, provide continued interest in the relationship between the virus and these haematological malignancies.