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Grossly-resected synovial sarcoma treated by the German and Italian Pediatric Soft Tissue Sarcoma Cooperative Groups: discussion on the role of adjuvant therapies.

Differently from adult oncologists that considered synovial sarcoma (SS) a tumor with uncertain chemosensitiveness, since two decades pediatric oncologists in Europe assumed that chemotherapy played an important role in SS treatment, so most pediatric patients were included in rhabdomyosarcoma protocols, receiving adjuvant chemotherapy regardless of risk factors. The German and Italian groups reviewed the data of grossly resected SS patients in order to define a risk-adapted treatment program for the next European protocol. A total of 150 patients < 21 years with localized SS who underwent initial gross resection between 1975 and 2002 were the object of this study. All but four cases received adjuvant chemotherapy. Post-operative radiotherapy was administered to 50% Group I and to 92% Group II patients. Five-year event-free survival (EFS) and overall survival (OS) were 77% and 89%, respectively. Survival rates were influenced by tumor size (EFS 92% and 56% for size < or = and > 5 cm, respectively) and local invasiveness, not by surgical margins. No metastatic relapses occurred in Group I < or = 5 cm patients, while the outcome was poor for T2B patients (EFS 41%) due to a high rate of metastatic relapse. Our study was unable to assess the role of adjuvant treatments in grossly-resected SS, but identified a subset of low-risk patients (IRS Group I, size < or = 5 cm), for which the omission of adjuvant chemotherapy could be suggested, and a subset of high-risk patients (T2B), who need treatment intensification.

Adolescent↗

Treatment of unresectable or metastatic pediatric soft tissue sarcomas with surgery, irradiation, and chemotherapy: a Pediatric Oncology Group study.

BACKGROUND: The objectives of this study were to compare vincristine/actinomycin D/cyclophosphamide/adriamycin (VACA) with VACA/plus imidazole carboxamide (DTIC) (VACAD) therapy in regards to complete/partial response and event free survival rates in children and adolescents with metastatic non-rhabdomyosarcoma soft tissue sarcomas (NRSTS) or previously chemotherapy-naive recurrent NRSTS or locally persistent gross residual tumor after surgery and radiation therapy. PROCEDURES: Between 1986 and March 1994, 75 patients entered this randomized study comparing VACA and VACAD, given at 3 week intervals. Sixty-one patients were considered eligible and received chemotherapy and radiation therapy to the primary tumor and areas of metastases. Thirty-six patients had regional unresected (Group III) disease, and 25 had metastatic disease (Group IV) at time of accession. Thirty-six patients received VACA (11 were not randomized), and 25 received VACAD. RESULTS: With a median follow-up of greater than 4 years, overall and event-free survival for all eligible patients are 30.6% and 18.4% respectively (S.E: 9.5% and 6.8%). There was insufficient evidence that DTIC offered any advantage to event free survival, but there was evidence for better outcome for patients in Group III disease in comparison to patients with Group IV disease, and for patients with a Grade 1 and 2 histology in comparison to Grade 3 lesions. CONCLUSIONS: Combination chemotherapy with VACA and VACAD were insufficient to prevent recurrent or progressive disease in children and adolescents with high stage NRSTS. The use of vincristine/ifosfamide/doxorubicin with cytokine support is under study.

Adolescent↗

The IVADo regimen--a pilot study with ifosfamide, vincristine, actinomycin D, and doxorubicin in children with metastatic soft tissue sarcoma: a pilot study of behalf of the European pediatric Soft tissue sarcoma Study Group.

BACKGROUND: The role of doxorubicin (Doxo) as part of multidrug regimens used to treat children with soft tissue sarcoma (STS) is controversial. To evaluate the feasibility of combining Doxo with the well established ifosfamide, vincristine, and actinomycin D (IVA) regimen, the Italian STS Committee performed a pilot study on a series of children with metastatic STS. METHODS: Between July 2002 and February 2004, 29 evaluable patients were enrolled in this study; 19 patients had rhabdomyosarcoma, 5 patients had peripheral neuroectodermal tumor, and 5 patients had other types of STS. The IVA-Doxo (IVADo) regimen included ifosfamide 3 g/m(2) on Days 1 and 2, vincristine 1.5 mg/m(2) on Day 1, actinomycin D 1.5 mg/m(2) on Day 1, and Doxo 30 mg/m(2) on Days 1 and 2. Three courses of IVADo were to be administered in the initial part of treatment and analyzed for toxicity and tumor response. RESULTS: Overall, 92 cycles were delivered. Major regimen-related toxicity was myelosuppression, with Grade 4 neutropenia in 67% of cycles and fever and neutropenia in 37% of cycles. Nonhematologic toxicity included Grade 3-4 mucositis (6.5% of cycles), constipation (9.7%), and peripheral neuropathy (6.5%). Other manifestations of major toxicity were venoocclusive disease and seizures, which occurred in one patient each. All but 1 patient with a malignant schwannoma showed some degree of tumor volume reduction; however, considering only complete and partial remissions, the response rate was 76% (+/- 7.9%). CONCLUSIONS: The intensive IVADo regimen was effective against pediatric STS with acceptable toxicity. This combination will be investigated in high-risk patients with rhabdomyosarcoma in a randomized trial launched by the European pediatric Soft tissue sarcoma Study Group.

Adolescent↗

Comprehensive Multiplatform Tyrosine Kinase Profiling Reveals Novel Actionable FGFR Aberrations across Sarcomas Affecting the Young.

Limited targeted agents are approved for pediatric sarcomas. Tyrosine kinase (TK) inhibitors (TKi) have shown clinical efficacy in some, but not all, young patients with sarcoma. A major obstacle preventing further advances and clinical implementation is the lack of predictive response biomarkers to guide TK-targeted treatments. TK-activating fusions or mutations are rare in these patients. RNA overexpression of TKs is a frequent feature. The unresolved question is when upregulated TK expression is associated with kinase activation and signaling dependence. We explored the TK molecular landscape of 107 patients with sarcoma from the ZERO Childhood Cancer Precision Medicine Program (ZERO) using whole-genome and -transcriptome sequencing. Phosphoproteomic analyses of tyrosine phosphorylation (pY) and functional in vitro and in vivo assays were performed in cell lines and patient-derived xenografts (PDX). Our analysis shows that although novel genomic driver lesions are rare, when present they are therapeutically actionable as exemplified by a novel LSM1-FGFR1 fusion identified in a patient with osteosarcoma. We further show that in certain contexts, TK RNA expression can indicate TK pathway activity and predict TKi sensitivity. We highlight the utility of FGFR inhibitors in PAX3-FOXO1 fusion-positive rhabdomyosarcomas (FP-RMS) characterized by high FGFR4 and FGF8 RNA expression levels and FGFR4 activation (FGFR4_pY). We demonstrate marked tumor growth inhibition in all FP-RMS PDXs treated with single-agent FGF401 (FGFR4-specific inhibitor) and single-agent lenvatinib (multikinase FGFR inhibitor) and report a clinical response to lenvatinib in a patient with relapsed metastatic FP-RMS. Altogether, we identified new patients with sarcoma who may benefit from FGFR inhibitors, most notably FP-RMS via FGFR4/FGF8 coexpression.

Journal Article↗

Immunohistochemistry of childhood sarcomas: old and new markers.

The frequent difficulties encountered in the diagnosis of pediatric sarcomas, caused by the lack of observable differentiation at the light microscopic level, has led to the routine use of immunohistochemistry in pediatric surgical pathology. To a large degree the advent of this staining technique has led to the correct assessment of many perplexing lesions that previously would have been given inconclusive diagnoses. However, with increased usage and testing, it has become apparent that there are few, if any, "magic bullets" in immunohistochemistry for pediatric pathologists. Thus, it behooves diagnosticians to be careful in the usage of this technique, to be aware of possible discrepancies in its results, and to remember the ancillary nature of its application. The following article will review selected markers commonly used in pediatric surgical pathology, from both previous reports and the author's perspective, and will briefly consider several new phenotypic markers which have potential utility with childhood sarcomas.

Actins↗

Hormone binding in brain tumors.

Brain tumors from 64 patients were studied for the presence of hormone binding. Estradiol binding was detected in 34 patients: 13 of 21 meningiomas, 4 of 8 schwannomas, 1 oligodendroglioma, 1 of 5 benign gliomas, 4 of 5 malignant gliomas, 5 of 11 metastatic tumors, and 6 of 11 pediatric tumors: 1 medulloblastoma, 2 malignant ependymomas, 1 benign astrocytoma, 1 malignant sarcoma, and 1 malignant teratoma. Eleven patients were studied for progesterone binding, which was measurable in 7: 1 schwannoma, 3 meningiomas, 1 malignant sarcoma (pediatric group), 1 astrocytoma--gemistocytic (pediatric group), and 1 metastatic adenocarcinoma. There were 41 females and 23 males in the study. Fifteen females were premenopausal, 18 were postmenopausal, and 8 were in the pediatric group. Of the 34 tumors with measurable estradiol binding, 23 occurred in females. In the progesterone group, 4 of the 7 tumors with measurable binding activity were from female patients. In the pediatric group, estradiol binding was detected in 1 medulloblastoma, 2 malignant ependymomas, 1 malignant teratoma, 1 malignant sarcoma, and 1 astrocytoma. Five of the 6 pediatric tumors with estradiol binding were malignant, and both pediatric tumors with progesterone binding were also malignant. Of the 10 gliomas studied, 4 of the 5 malignant tumors had estradiol binding, whereas only 1 of the 5 benign tumors showed binding. Our studies with the pediatric tumors and the gliomas suggest that a relationship exists between the malignancy of the tumor and the presence of hormone binding. The ubiquitous nature of the presence of hormone binding is discussed, as is the possible correlation between age, sex, histological grade, and significance of hormone binding in brain tumors.

Adolescent↗

[Sarcoma botryoides in the pediatric vagina--a soft tissue sarcoma with good prognosis].

Although rare, sarcoma botryoides of the vagina in infants is a highly aggressive soft tissue tumour. Former opinions suggesting exenterative surgery and radiation to improve the dismal outcome in these young children, are outdated. Due to balanced therapies (topical tumourectomy, chemotherapy and radiation adjusted to tumour stage) cure of these sarcomas may be expected dependent on tumour stage, localisation and response to chemotherapy. The rate of complete remissions has increased in recent years. We report on an eighteen-month old girl with complete remission of tumour stage IIA who had been treated according to the CWS 91 protocol. Diagnosis and treatment were performed in March 1994 at the age of six months. We observed the patient in complete remission for 8 months (till September 1995).

Biomarkers, Tumor↗

Phase II trial of ifosfamide with mesna in previously treated metastatic sarcoma.

Ifosfamide given to 42 patients iv at 2-2.5 g/m2/day X 4 resulted in partial responses in ten of 28 (36%) evaluable patients with adult soft tissue sarcomas, including two of two with chondrosarcoma; none of nine with pediatric sarcomas (Ewing's sarcoma, osteogenic sarcoma, or rhabdomyosarcoma) achieved partial response. All of the pediatric patients had failed to respond to complicated three- to six-drug regimens of up to 18 months in duration. The response rates in patients with and without prior cyclophosphamide (32%; seven responses among 22 patients; and 20%, three responses among 15 patients) were not significantly different, supporting in vitro evidence of a lack of cross-resistance between the two related compounds. Myelosuppression was dose-limiting. Hemorrhagic cystitis was not observed in patients treated with 400-500 mg of mesna iv every 4 hours during ifosfamide treatment. Nausea and vomiting were generally mild or moderate. Alopecia was universal but reversible. Of the first 11 patients, five became somnolent or developed visual hallucinations (during six of the 12 total courses administered to the five patients). Only one patient had two episodes of neurotoxicity. After reduction of the use of iv antiemetics and major narcotics, single episodes of neurotoxicity were seen in five of the next 27 patients. An asymptomatic acidosis developed in most patients, requiring bicarbonate replacement in one. Ifosfamide appears to be active in previously treated patients with sarcomas and should be evaluated in patients with less extensive prior treatment.

Adolescent↗

Sarcomas of the head and neck region.

PURPOSE OF REVIEW: This review discusses the classification, etiology, diagnosis, evaluation, treatment, and prognosis of sarcoma of the head and neck region. RECENT FINDINGS: Sarcomas account for less than 1% of all malignancies in the United States with only 5 to 15% of these sarcomas occurring in the head and neck region. However, about 1 in 3 pediatric sarcomas will occur in the head and neck region. Occasionally, these tumors are associated with genetic syndromes or previous radiation exposures, but, most commonly, no clear etiology exists. Pathologic classification is critical to the ultimate treatment and prognosis of sarcoma of the head and neck. Osteosarcoma, rhabdomyosarcoma, malignant fibrous histiocytoma, and angiosarcoma are the most common types of sarcoma to occur in the head and neck region; however, up to 20% of head and neck sarcomas will remain unclassified. Surgery has been central to the management of these malignancies with some exceptions in the pediatric population. Adjuvant chemotherapy is being utilized and/or studied for most high-grade sarcomas and adjuvant radiotherapy is important for disease control in high-grade soft-tissue sarcomas. Prognosis is clearly related to tumor grade and margin status. SUMMARY: Sarcomas of the head and neck region are rare malignancies often without a clear etiology. Expert pathologic review and classification is critical, as are quality imaging and multidisciplinary management.

Adolescent↗

Multidisciplinary management of pediatric soft-tissue sarcoma.

The management of pediatric soft-tissue sarcomas has improved drastically through the use of multimodal therapy. These tumors include rhabdomyosarcomas and nonrhabdomyosarcomas. Both are staged using physical, radiographic, and histologic evaluation, and both have intricate staging and grouping systems that correlate closely with prognosis. However, approaches to therapy for the two tumor types remain somewhat different. Rhabdomyosarcomas are treated primarily with chemotherapy. Surgical intervention is limited to initial biopsy, wide local excision when clear margins are feasible, and resection of residual disease. Radiation therapy is reserved for patients with persistent or recurrent disease and may be delivered by external beam or brachytherapy. Nonrhabdomyosarcomas are best treated primarily by surgical resection, although radiation and chemotherapy are now being used with some success. Another major difference concerns evaluation of lymphatics. Nonrhabdomyosarcomas in children frequently behave similarly to adult sarcomas, and less commonly involve regional lymph nodes, whereas pediatric patients with rhabdomyosarcomas often have nodal involvement necessitating surgical evaluation of regional lymph nodes as part of the staging protocol. Multimodal therapy has led to improved survival as well as better functional and cosmetic results. With further clinical trials and improved techniques such as brachytherapy and lymphatic mapping with sentinel node biopsy, we expect to continue to optimize therapy for pediatric patients with soft-tissue sarcomas.

Child↗

A prospective study of nonrhabdomyosarcoma soft tissue sarcomas in the pediatric age group.

Nonrhabdomyosarcoma soft tissue sarcomas in infants and children are rare malignancies with most of the clinical data gained by retrospective analysis. In 1986, a prospective multicentered study was initiated by the Pediatric Oncology Group (POG) with a total of 75 cases now entered for epidemiologic examination. Median age of presentation was 12 years (range, newborn to 20 years). The male to female ratio was 2.3 to 1. The most common soft tissue tumor was synovial cell sarcoma (32/75, 42%), followed by fibrosarcoma (10/75, 13%), malignant fibrous histiocytoma (9/75, 12%), and malignant neurogenic tumors (8/75, 10%). Sixty-five percent of all tumors presented on the extremities (44% lower extremity, 21% upper extremity). Tumors of the trunk accounted for 28% (abdomen 15%, thorax 13%), whereas head and neck tumors were 7%. By TNMG classification, 16% presented as stage I, 21% as stage II, 33% as stage III, and 30% as stage IV. Age at presentation did not affect clinical site or stage. All upper extremity tumors presented with localized disease, whereas lower extremity tumors presented with regional nodal disease in 7% and metastatic disease (pulmonary) in 23% of the cases. Seventy-eight percent of the abdominal tumors were metastatic at diagnosis; the other 22% had extensive regional disease. In the thorax 78% had localized lesions with 22% having extensive regional disease. Ninety percent of synovial cell sarcomas were on the extremities: 84% localized disease and 12% metastatic spread at presentation. Sixty percent of the fibrosarcomas presented on the extremities with 80% having localized disease and 20% metastatic spread. Only 25% of the neurogenic tumors presented with localized disease, whereas 50% had metastases at the time of diagnosis.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗

Pediatric soft tissue sarcomas of nonmyogenic origin.

Nonrhabdomyosarcoma soft tissue sarcomas (NRSTS) are relatively rare tumors, which nonetheless constitute 50% of the soft tissue sarcomas seen in the pediatric population. The prognosis for these tumors is good, with 92% of patients in our series alive and 61% free of their disease at 5 years follow-up. The most important prognostic factor among our 35 patients was the grade of the tumor. More than 70% of our patients with grade I or II lesions are disease-free at 5 years, compared to only 39% of patients with grade III lesions. The patients with the best outlook are those who can be treated with surgery alone as the definitive care for this disease. Resection remains the primary treatment modality in NRSTS, whereas, unlike the treatment of rhabdomyosarcomas, the value of radiation therapy and chemotherapy in treating NRSTS remains undefined.

Child↗

RT-PCR evaluation of peripheral blood, bone marrow and peripheral blood stem cells in children and adolescents undergoing VACIME chemotherapy for Ewing's sarcoma and alveolar rhabdomyosarcoma.

Peripheral blood stem cell support allows dose intensification of multiple cycle chemotherapy for metastatic tumors, including pediatric sarcomas. The VACIME protocol (vincristine, adriamycin, cyclophosphamide, ifosfamide, mesna and etoposide) utilizes peripheral blood stem cells (PBSC) collected following the treatment cycle as support for subsequent dose- and time-intensive chemotherapy. A critical assumption is that PBSC collected in this manner will be purged of residual tumor cells in vivo. We tested this assumption using sensitive reverse-transcriptase polymerase chain reaction (RT-PCR) to assess the presence of the characteristic translocations of the Ewing's sarcoma family of tumors (ESFT) and alveolar rhabdomyosarcoma (ARMS), t(11;22), and t(2;13), respectively. We used RT-PCR to evaluate 122 samples of peripheral blood (PB), bone marrow (BM) and PBSC collected from 12 pediatric patients with metastatic ESFT and ARMS. The samples included pre-therapy BM and PB, as well as BM, PB, and PBSC collections at various times in the VACIME treatment course. Molecular evidence of tumor contamination was detected in 1/40 PBSC collections from 12 patients. In all patients, we documented clearance of disease by RT-PCR in peripheral blood and bone marrow by week 9 of the VACIME protocol. In vivo purging in combination with the intensive VACIME regime appears to be effective in removing tumor cells from PBSC, bone marrow, and peripheral blood as detected by RT-PCR.

Adolescent↗

Neuroectodermal and neuroendocrine tumors principally seen in children.

Neuroectodermal tumors comprise a large proportion of childhood neoplasms. Neuroblastic tumors, including neuroblastoma, ganglioneuroblastoma, and ganglioneuroma, are the most frequent extracranial solid cancers of childhood, occurring primarily in infants and toddlers. Primitive neuroectodermal tumors, including Ewing sarcoma and peripheral neuroepitheliomas, occur most frequently in older children and adolescents, and as pediatric sarcomas are second in frequency only to rhabdomyosarcomas. Rarer neuroectodermal tumors include desmoplastic small cell tumors, esthesioneuroblastomas, and melanotic neuroectodermal tumors, the first two entities occurring as rather site-specific lesions in the abdomen and nose, respectively. Diagnosis can be difficult due to the undifferentiated nature of many of these cancers, but ancillary studies, including electron microscopy, immunohistochemistry, cytogenetics, and molecular genetics, enhance their recognition. The molecular nature of childhood neuroectodermal tumors is as diverse as their histology, ranging from the fusion genes characterizing the Ewing sarcoma family of tumors to the proto-oncogene amplification seen in aggressive neuroblastomas.

Adolescent↗

Sensitive detection of rare Ewing's sarcoma cells in peripheral blood by reverse transcriptase polymerase chain reaction.

Disseminated disease is very important in the clinical assessment of pediatric sarcomas. Several reports suggest that reverse transcriptase polymerase chain reaction (RT-PCR) holds great promise in the early staging of cancer patients in general. However, the complexities of these protocols hamper adequate standardization, and their application as routine diagnostic tools has been difficult. The aim of this study is to assess the actual minimal number of tumor cells that may be detected by RT-PCR in a blood sample. Specific tumor cell dilutions from a Ewing's sarcoma cell line reconstituted in peripheral blood from healthy individuals were "ficolled" and submitted to RNA extraction for cDNA preparation and PCR amplification of the t(11-22) (q24;q12) fusion transcript. After PCR amplification, we were able to detect the EWS/FI-1 chimeric gene product at a dilution of 10 tumor cells per 1 or 2 mL of blood. Our simple method supports a role for routine clinical use of RT-PCR in the detection of circulating Ewing's sarcoma cells.

Artificial Gene Fusion↗

Aberrant immunohistochemical expression in nonrhabdomyosarcoma soft tissue sarcomas of infancy: retrospective review of clinical material.

Malignant soft tissue tumors other than rhabdomyosarcoma (RMS) are uncommon in infancy, representing approximately 5% of pediatric sarcomas. The pathological categorization of non-RMS soft tissue malignancies from these young patients is complicated by variation in both morphologic and immunohistochemical features. A search covering an 11-year period identified 19 patients presenting at birth or in infancy with a clinical or referral diagnosis of soft tissue sarcoma. After histologic and immunohistochemical review, nine of these tumors were classified as primitive neuroectodermal tumor (PNET), three as infantile hemangiopericytoma (HPC), two as infantile fibrosarcoma (FS), and five as undifferentiated sarcoma. Those identified as undifferentiated sarcomas showed an atypical spindle and ovoid cell morphology, with cellular pleomorphism and high mitotic rate, but lacking the fascicular growth pattern of classic infantile fibrosarcoma. Immunohistochemical staining in this group showed variable weak positivity for a range of markers (desmin, smooth muscle actin, Myo-D1, PGP, NSE, S100, CO56, cytokeratin, and CD99), and did not fit readily into any distinct diagnostic category. In this series, tumors classified as soft tissue PNETs had a poor prognosis despite aggressive treatment. However, once RMS, PNET, and other rare specific lesions are excluded, the remaining undifferentiated sarcomas, despite their unusual morphology and immunohistochemistry, appear to behave in a similar favorable manner to infantile fibrosarcoma.

Humans↗

Adenovirus-mediated p53 gene therapy in pediatric soft-tissue sarcoma cell lines: sensitization to cisplatin and doxorubicin.

Sarcomas, or tumors of connective tissue, represent roughly 20% of childhood cancers. Although the cure rate for sarcomas in general has significantly improved in the last 10 years, there continue to be subgroups that are difficult to treat. High-grade or metastatic soft-tissue sarcomas and rhabdomyosarcomas (RMS) of the extremities remain therapeutic challenges and their prognosis is often poor. The future of sarcoma therapy will likely include molecular approaches including gene/protein expression profiling and gene-based therapy. Most sarcomas harbor defects in the p53 or pRb pathways. The tumor suppressor p53 is central to regulation of cell growth and tumor suppression and restoring wild-type p53 function in pediatric sarcomas may be of therapeutic benefit. Studies with adenoviral-mediated p53 gene transfer have been conducted in many cancer types including cervical, ovarian, prostatic and head and neck tumors. Studies of this approach, however, remain limited in pediatric cancers, including sarcomas. Using three viral constructs containing cDNA for wild-type p53, mutant p53 (C135S) and lacZ, we studied the effect of adenoviral-mediated gene therapy in four pediatric sarcoma cell lines, RD and Rh4 (RMS), Rh1 (Ewing's sarcoma) and A204 (undifferentiated sarcoma). Using the MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide) assay, we have shown a dose-dependent decrease in cell viability 72 h post-treatment that occurs with Ad-wtp53 but not with Ad-mutp53. Cells treated with Ad-wtp53 show upregulation of the p53 downstream targets, p21(CIP1/WAF1) and bax. Growth curves demonstrate suppression of cell growth over a period of 4 days and cells treated with Ad-wtp53 demonstrate a significant increase in sensitivity to the chemotherapeutic agents, cisplatin and doxorubicin. Our results indicate that restoration of wild-type p53 function in pediatric sarcoma cells could provide a basis for novel approaches to treatment of this disease.

Adenoviridae↗

Multiplex RT-PCR assay for the differential diagnosis of alveolar rhabdomyosarcoma and Ewing's sarcoma.

Cytogenetic analysis has defined specific translocations associated with two of the most common small round cell tumors of childhood, t(11;22) in Ewing's sarcoma and t(2;13) in alveolar rhabdomyosarcoma. We and others have previously demonstrated the diagnostic utility of a reverse transcriptase polymerase chain reaction (RT-PCR) assay for the detection of the t(11;22) encoded EWS/FLI-1 chimeric message in Ewing's sarcoma. More recently, we have cloned the t(2;13)(q35;q14) translocation and have shown that it results in the fusion of the PAX3 gene on chromosome 2 to FKHR, a novel member of the fork-head family of transcription factors on chromosome 13. To define the morphological spectrum of childhood sarcomas that express the t(2;13) encoded PAX3/FKHR chimeric message, we have performed RT-PCR analysis on samples from 44 primary pediatric sarcomas and 8 sarcoma cell lines. PAX3/FKHR chimeric messages were detected in 24 of 27 alveolar, 2 of 12 embryonal, and 0 of 1 pleomorphic rhabdomyosarcoma and in 1 of 2 ectomesenchymomas. In contrast, none of 8 Ewing's sarcomas or 2 undifferentiated sarcomas expressed this message. Chimeric transcripts were detected in all cases with cytogenetic evidence of the (2;13) translocation, and in each case the chimeric PAX3/FKHR message had the identical junction sequence, suggesting that genomic chromosome breaks were clustered in a single intron in both genes. By combining the PAX3/FKHR RT-PCR assay with primers for detection of the Ewing's sarcoma t(11;22) encoded EWS/FLI-1 chimeric transcript, we have developed a multiplex RT-PCR reaction that allows the rapid and accurate identification of either translocation in a biopsy sample.

Base Sequence↗