Molecular Genetics in the Diagnosis and Prognosis of Solid Pediatric Tumors

The field of molecular genetics continues to see an ever increasing number of applications to pediatric tumor analysis. Studies in pediatric tumors have identified novel genes and other genetic changes, a large number of which reflect one of the following mechanisms: (1) activation of proto-oncogenes; (2) loss of tumor suppressor genes; or (3) creation of novel fusion proteins. At least one of these mechanisms is operational in each of the following pediatric tumors: neuroblastoma, Ewing sarcoma and peripheral primitive neuroectodermal tumor (pPNET), intra-abdominal desmoplastic small-cell tumor, rhabdomyosarcoma, synovial sarcoma, and Wilms tumor. Out of this research has come not only an increased understanding of oncogenesis but also, for each of the tumors listed above, diagnostic and/or prognostic markers that can be used by the pathologist and oncologist to improve overall patient management. Received November 20, 1997; accepted April 20, 1998.     

Cyclooxygenase-2 expression does not correlate with outcome in osteosarcoma or rhabdomyosarcoma

PURPOSE: To determine if expression of cyclooxygenase (COX)-2, an inducible enzyme with known tumor-promoting activity, correlates with outcome in pediatric sarcomas. COX-2 overexpression correlates with more aggressive disease in a variety of adult solid tumors. METHODS: Archived human osteosarcoma, rhabdomyosarcoma, and Ewing sarcoma tumors were retrospectively evaluated, blinded to outcome, for COX-2 expression by immunohistochemistry and correlated with patient characteristics and survival. RESULTS: COX-2 expression was detected in 94 of 142 (66%) tumors (osteosarcoma, 66/99 [67%]; rhabdomyosarcoma, 21/35 [60%]; Ewing sarcoma, 7/8 [88%]) and 51 of 85 (60%) diagnostic biopsies (osteosarcoma, 26/45 [58%]; rhabdomyosarcoma, 21/35 [60%]; Ewing sarcoma, 4/5 [80%]). COX-2 expression did not vary with clinicopathologic features and was not predictive of prognosis in these cases. CONCLUSIONS: This study does not support the use of COX-2 expression as an upfront prognostic variable in patients with osteosarcoma or rhabdomyosarcoma.Results from the small number of patients studied with Ewing sarcoma suggest a similar lack of predictive value for COX-2 expression. However, COX-2 inhibitors are not entirely dependent upon enzyme expression for their antitumor effects; this study does not necessarily preclude the use of COX-2 inhibitors for the treatment of pediatric sarcomas.     

Immunotherapy with autologous dendritic cells and tumor antigens for children with refractory malignant solid tumors

Abstract:  Immature DCs were generated from the peripheral blood monocytes from five children with refractory solid tumors (Ewing sarcoma, synovial sarcoma, neuroblastoma) using GM-CSF and IL-4. These DCs were then pulsed with tumor-specific synthetic peptides or tumor lysates in the presence of the immunogenic protein KLH for 12 h. Pulsed DCs were administered subcutaneously every one or two weeks in an outpatient setting without any toxicity. In one patient with Ewing sarcoma, the residual tumor disappeared following autologous PBSCT and DC therapy, and a complete remission has been maintained for 77 months. In two patients with synovial sarcoma or with neuroblastoma, growth of the tumors was temporally suppressed for one and 10 months, respectively, followed by their exacerbation. A DTH response was detected against KLH in all five patients and against the tumor lysate in one patient. In the patients with a possible DC-mediated anti-tumor effect, the number of CD8⁺ HLA-DR⁺ lymphocytes and INF-γ⁺CD8⁺ lymphocytes increased and an elevation of the NK cell cytotoxic activity was observed during and/or after DC therapy. DC-based immunotherapy may therefore be a feasible, well-tolerated and promising approach in the treatment of children with refractory malignant tumors.     

Extracellular Matrix of Small Round cell Tumors of Childhood: An Immunohistochemical Study of 67 Cases

Sixty-seven childhood tumors were studied immunohistochemically for the extracellular matrix elements type IV collagen, laminin, and fibronectin. Tumors included Ewing's sarcoma, primitive neuroectodermal tumor, small cell osteosarcoma, neuroblastoma or ganglioneuroblastoma, rhabdomyosarcoma, and lymphoma. It was found that small cell osteosarcoma was often positive for fibronectin but not type IV collagen or laminin, a new observation. In the lymphomas, matrix proteins were rarely found. Ewing's sarcoma was variably positive for type IV collagen and laminin, but fibronectin was absent. Extracellular laminin and fibronectin were found in one of two cases of primitive neuroectodermal tumor. In neuroblastoma and ganglioneuroblastoma, the matrix components were rarely found. These results, discrepant with findings in cultured cells, may reflect the altered capacity of tumors to produce these proteins in vitro, which suggests that caution should be exercised in drawing conclusions regarding the nature or histogenesis of tumors from data obtained with cultured tumor cells. Embryonal rhabdomyosarcoma frequently contained all matrix elements in the extracellular space and in a dotlike pattern in the cytoplasm; alveolar rhabdomyosarcoma rarely contained these proteins and never exhibited the dotlike pattern. The frequent finding of matrix proteins in embryonal rhabdomyosarcoma but only rarely in alveolar rhabdomyosarcoma and the unique immunostaining pattern in embryonal rhabdomyosarcoma may prove to be a useful adjunct in the diagnosis of childhood tumors.     

Phase II trial of pyrazoloacridine in children with solid tumors: a Pediatric Oncology Group phase II study

PURPOSE: Pyrazoloacridine (PZA), a rationally synthesized deoxyribonucleic acid (DNA) binding agent that preferentially inhibits ribonucleic acid rather than DNA synthesis, is active against hypoxic and noncycling tumor cells and has greater in vitro activity against a broad range of human solid tumor lines than against the L1210 murine leukemia line. The Pediatric Oncology Group conducted a phase II study to determine the activity of PZA administered as a 3-hour infusion. PATIENTS AND METHODS: The activity of PZA was evaluated in patients with a variety of childhood solid tumors including rhabdomyosarcoma, Ewing sarcoma/peripheral neuroectodermal tumor, neuroblastoma, osteogenic sarcoma, Wilms tumor, or other solid tumors (excluding brain tumors). In addition to a standard three-stage design to test the drug's activity in each tumor type, a global stopping rule was used such that if no complete or partial responses (CR or PR) occurred in the first 35 patients (pooled across all strata except "other"), the study would be closed. RESULTS: A total of 47 patients were entered into the study. Myelosuppression was the primary toxicity. Severe nonhematologic toxicity was uncommon. Only one patient exhibited grade 3 neurologic toxicity (anxiety). No CRs or PRs were observed. CONCLUSION: Use of the global stopping criterion permitted early identification of lack of activity of PZA against childhood solid tumors.     

Differential susceptibility of pediatric sarcoma cells to oncolysis by conditionally replication-competent herpes simplex viruses

PURPOSE: Attenuated viruses derived from herpes simplex virus (HSV) type 1 that kill tumor cells (oncolysis) are currently in clinical trials for selected cancers, primarily carcinomas and gliomas. The authors sought to determine if pediatric sarcoma cells are also sensitive to HSV-mediated oncolysis. MATERIALS AND METHODS: The authors tested a panel of ten cell lines derived from rhabdomyosarcoma, osteosarcoma, Ewing sarcoma, and a secondary malignant fibrous histiocytoma for survival after exposure to attenuated HSV vectors. The viruses used included NV1020, haploid for the neurovirulence gene, and G207, deleted for both and ribonucleotide reductase but expressing the beta-galactosidase reporter gene. G207 transduction was determined by measuring beta-galactosidase expression. RESULTS: Sarcoma cells differed in their sensitivity to viral oncolysis but were relatively consistent by histologic type. Rhabdomyosarcoma and malignant fibrous histiocytoma cells were most sensitive while osteosarcoma cells were intermediately sensitive to oncolysis by both HSV recombinants. Although Ewing sarcoma cells showed efficient viral entry and gene transfer, these cells were the least susceptible to oncolysis by HSV. CONCLUSIONS: Conditionally replication-competent HSV-derived vectors may be useful for the treatment of rhabdomyosarcoma and osteosarcoma, but may not be as efficacious for treating Ewing sarcoma until the mechanism of resistance is defined and circumvented.     

Selection of human antitumor single-chain Fv antibodies from the B-cell repertoire of patients immunized against autologous neuroblastoma

BACKGROUND: We used phage display technology to clone human recombinant antitumor antibodies from the antibody repertoire of neuroblastoma patients immunized with cytokine-gene transduced tumor cells. PROCEDURE: Lymphocytes obtained from neuroblastoma patients either at diagnosis or after immunization with an autologous interleukin-2 gene transduced tumor vaccine were used to construct two human single-chain Fv (scFV) phage libraries. Tumor-reactive phage were characterized using ELISA, flow cytometry, and sequencing analysis. RESULTS: The initial screening after panning on neuroblastoma cells yielded a substantially higher proportion of selectivity tumor-binding phage clones derived from the immunized patients library (12.9%) than from the unvaccinated patients library (0.8%). The antibodies stained the cells from several additional pediatric malignancies, including Ewing sarcoma and rhabdomyosarcoma, in the absence of binding to any normal tissue cultures or epithelial tumor cell lines. The pattern of reactivity was different from that of antibodies recognizing other widely distributed neuroblastoma-associated antigens, suggesting recognition of a novel shared tumor antigen. CONCLUSION: The human recombinant scFV antibodies reported here appear to represent a tumor-specific B-cell response induced by autologous tumor immunization and are potentially useful targeting moieties for the treatment of selected childhood tumors.     

Ifosfamide, carboplatin, and etoposide (ICE) reinduction chemotherapy in a large cohort of children and adolescents with recurrent/refractory sarcoma: the Children's Cancer Group (CCG) experience

BACKGROUND: The prognosis for children with recurrent/refractory sarcomas is poor. We determined the overall response rate (ORR) and overall survival (OS) of children with recurrent/refractory sarcomas who were given ifosfamide, carboplatin, and etoposide (ICE) in three Children's Cancer Group (CCG) phase I/II trials. PROCEDURE: Children with recurrent/refractory sarcoma were treated with ifosfamide (1,800 mg/m2/day on day 0-4), carboplatin (400 mg/m2/day on day 0-1), etoposide (100 mg/m2/day on day 0-4) and either rhG-CSF (10 microg/kg/day vs. 5 microg/kg/day, CCG-0894, 71 patients), PIXY321 (500-1,000 microg/m2/day, CCG-0924, 14 patients), or rhG-CSF (5 microg/kg/day) and IL-6 (2.5-5 microg/kg/day, CCG-0931, 12 patients). RESULTS: Ninety-seven patients were evaluable for tumor response, 56 male and 41 female, median age 14.1 years (range 2.8-22.5 years). Tumor types were osteosarcoma (OTS) (n = 34), rhabdomyosarcoma (n = 27), Ewing sarcoma (EWS) (n = 21), soft tissue sarcoma-not otherwise specified (n = 5), undifferentiated sarcoma (n = 6), fibrosarcoma (n = 2), peripheral primitive neuroectodermal tumor (n = 1), and extraosseous Ewing (n = 1). The ORR was 51% (27% complete response [CR]). OS at 1 and 2 years was 49% and 28%, respectively. Patients with CR or partial response (PR) had significantly increased 1- and 2-year OS, 71% and 41%, respectively, (P < 0.001). Rhabdomyosarcoma patients with embryonal histology had significant improvement in 1- and 2-year OS: 82% and 46%, respectively, compared with other histologies, (P < 0.005). CONCLUSIONS: The ORR to ICE reinduction chemotherapy in children with recurrent/refractory sarcoma was 51%. OS of 1 and 2 years appeared significantly improved in patients who had CR or PR following ICE reinduction therapy or who had rhabdomyosarcoma with embryonal histology.     

Combination chemotherapy with adriamycin (NSC-123127) and dimethyl triazeno imidazole carboxamide (DTIC) (NSC-45388) in children with metastatic solid tumors

Combination chemotherapy with adriamycin and DTIC was used in 102 evaluable patients under 15 years of age who had previously treated metastatic solid tumors. Responses, defined as 50% or more reduction in all tumor masses, occurred in 10 out of 27 patients with neuroblastoma, 3 out of 8 patients with Wilms tumor, 7 out of 15 patients with Ewing sarcoma, 2 out of 6 patients with osteosarcoma, 5 out of 13 patients with rhabdomyosarcoma, and 15 out of 33 patients with miscellaneous tumors which included a patient who had a complete regression of an extensive juvenile angiofibroma. Response rate to combination chemotherapy with adriamycin and DTIC in patients with Ewing sarcoma was significantly superior to the response rate obtained with adriamycin alone in another Southwest Oncology Group Study. Major toxicity included nausea, vomiting, myelosuppression, high incidence of pneumocystis carinii pneumonia (5 patients) and congestive heart failure (4 patients). There were 7 drug-associated deaths due to sepsis (1), pneumocystis carinii pneumonia (4), and congestive heart failure (2).     

Second and third malignant solid tumor in a girl with ovarian Sertoli-Leydig tumor

We report a Sertoli-Leydig cell (SLC) tumor of the right ovary in a 10-year-old girl, which was dealt with surgical removal. Three months after resection, she presented with a new episode of acute abdomen because of an abdominal mass, which histologically was compatible with an undifferentiated embryonal rhabdomyosarcoma. Chemotherapy, according to SIOP-??? 89 protocol, was administered additionally to radiotherapy (3,960 cGy). Three years after completing treatment, the patient developed a painful swelling at her left upper arm. The diagnosis was Ewing sarcoma of the humerus, which was confirmed by identification of the typical 11; 22 translocation on cytogenetic and molecular analysis of the tumor tissue. The patient died 14 months from Ewing diagnosis due to progressive disease.     

Initial testing of the multitargeted kinase inhibitor pazopanib by the Pediatric Preclinical Testing Program

Pazopanib is an oral angiogenesis inhibitor targeting vascular growth factor receptor-1, -2, and -3, platelet derived growth factor receptor-α, platelet derived growth factor receptor-β, and KIT that has demonstrated activity against a variety of adult cancer xenografts. Pazopanib was tested against a panel of pediatric rhabdomyosarcoma and Ewing sarcoma xenografts at a dose of 108 mg/kg/day or 100 mg/kg twice daily, administered orally for 28 days. While no objective responses were observed, pazopanib induced statistically significant differences in event-free survival compared to controls in approximately one-half of the sarcoma xenograft models tested. Though well tolerated, pazopanib showed limited activity against the sarcoma models evaluated, with the best tumor responses being growth delay.     

Ewing sarcoma of the small intestine

This report describes a rare case of Ewing sarcoma (ES) of the small intestine. The patient was a 9-year-old girl with progressive abdominal distension. Computed tomography showed a large mass in the small bowel. Histopathologic examination of the resected tumor showed ES with typical histologic, immunohistochemical, and ultrastructural features. The tumor recurred in the pelvic cavity 18 months after the original surgery. Molecular study of the recurrent tumor confirmed a diagnostic EWS-FLI1 gene fusion. This patient illustrates the unique occurrence of ES in the small intestine.     

Evaluation of prognostic factors in a tumor volume-adapted treatment strategy for localized Ewing sarcoma of bone: the CESS 86 experience. Cooperative Ewing Sarcoma Study

BACKGROUND: The Cooperative Ewing Sarcoma Study (CESS 86), conducted by the German Society of Pediatric Oncology and Hematology (GPOH), was planned on the basis of the results of the preceding CESS 81 study. The prognostic significance of tumor volume in localized Ewing sarcoma of bone was well documented in the CESS 81 trial. As a consequence, the treatment intensity was adapted to volume in the follow-up CESS 86 trial: the four-drug combination used in CESS 81 was amended for patients with large tumor volume (> or = 100 ml), where ifosfamide was substituted for cyclophosphamide. PROCEDURE: From January 1986 to June 1991, 177 protocol patients with localized Ewing sarcoma of bone were registered in CESS 86. The prognostic implication of tumor volume and several covariates was evaluated using Kaplan-Meier life table analysis and Cox's proportional hazard model. RESULTS: The estimated 5- and 8-year event-free survival (EFS) rates were both 59%. Age, gender, tumor site, and a tumor volume of 100 ml did not distinguish groups of patients with different prognosis. However, the prognosis of patients with tumors >200 ml (8-year EFS rate: 42%) was significantly inferior compared to patients with tumors both of 100 to 200 ml (70%) and of <100 ml (63%). In contrast to CESS 81, the histological response to chemotherapy was no longer a significant prognostic factor (EFS: 64% for good and 50% for poor responders, respectively). CONCLUSIONS: Despite risk-adapted treatment intensity, tumor volume retained its prognostic significance; the cut point, however, was shifted toward larger volumes.     

Ewing sarcoma family of tumors express adenovirus receptors and are susceptible to adenovirus-mediated oncolysis

PURPOSE: Attenuated viruses derived from adenoviruses (Ad) that kill tumor cells (oncolysis) are currently in clinical trials for selected cancers. Some cancers have proven resistant to Ad infection due to low expression of viral receptors. The authors sought to determine whether members of the Ewing sarcoma family of tumors (ESFTs) express Ad receptors and are sensitive to Ad-mediated oncolysis. METHODS: Using flow cytometry, the authors tested a panel of cell lines derived from ESFTs for expression of both the Ad receptor, coxsackie-adenovirus receptor (CAR), and the cellular mediator of Ad uptake, alpha(v)-integrins, as well as for Ad-mediated gene transduction. Cell survival assays were used to assess the sensitivity to Ad-mediated oncolysis. Immunohistochemistry was used to assess CAR expression in primary tumors. mRNA levels of CAR in cell lines and tumor samples were also queried from a cDNA expression database. RESULTS: The ESFT cell lines expressed CAR and alpha(v)-integrins, showed high levels of gene transduction, and were highly sensitive to viral oncolysis. Primary tumor samples were positive for CAR expression by immunohistochemistry. Microarray analysis confirmed CAR expression in ESFT cell lines and tumors. CONCLUSIONS: Ewing sarcoma cells express the Ad receptors and are sensitive to Ad oncolysis. Treatment of Ewing sarcoma using conditionally replicative adenoviruses should be explored.