Alberto S. Pappo

Defects in succinate dehydrogenase in gastrointestinal stromal tumors lacking KIT and PDGFRA mutations

Carney-Stratakis syndrome, an inherited condition predisposing affected individuals to gastrointestinal stromal tumor (GIST) and paraganglioma, is caused by germline mutations in succinate dehydrogenase (SDH) subunits B, C, or D, leading to dysfunction of complex II of the electron transport chain. We evaluated the role of defective cellular respiration in sporadic GIST lacking mutations in KIT or PDGFRA (WT). Thirty-four patients with WT GIST without a personal or family history of paraganglioma were tested for SDH germline mutations. WT GISTs lacking demonstrable SDH genetic inactivation were evaluated for SDHB expression by immunohistochemistry and Western blotting and for complex II activity. For comparison, SDHB expression was also determined in KIT mutant and neurofibromatosis-1–associated GIST, and complex II activity was also measured in SDH-deficient paraganglioma and KIT mutant GIST; 4 of 34 patients (12%) with WT GIST without a personal or family history of paraganglioma had germline mutations in SDHB or SDHC. WT GISTs lacking somatic mutations or deletions in SDH subunits had either complete loss of or substantial reduction in SDHB protein expression, whereas most KIT mutant GISTs had strong SDHB expression. Complex II activity was substantially decreased in WT GISTs. WT GISTs, particularly those in younger patients, have defects in SDH mitochondrial complex II, and in a subset of these patients, GIST seems to arise from germline-inactivating SDH mutations. Testing for germline mutations in SDH is recommended in patients with WT GIST. These findings highlight a potential central role of SDH dysregulation in WT GIST oncogenesis.

Prognostic Factors and Clinical Outcomes in Children and Adolescents With Metastatic Rhabdomyosarcoma--A Report From the Intergroup Rhabdomyosarcoma Study IV

PURPOSE To identify risk factors associated with outcomes in children with metastatic rhabdomyosarcoma (RMS) treated on the fourth Intergroup Rhabdomyosarcoma Study (IRS-IV). PATIENTS AND METHODS Patients with metastatic RMS were treated with one of two regimens that incorporated a window of either ifosfamide and etoposide (IE) with vincristine, dactinomycin, and cyclophosphamide (VAC) or vincristine, melphalan (VM) and VAC. Study end points were failure-free survival (FFS) and overall survival (OS). Clinical factors including age, histology, sites of primary and metastatic disease, and number of sites of metastatic disease were correlated with those end points. RESULTS One hundred twenty-seven patients were eligible for analysis. The estimated 3-year OS and FFS for all patients were 39% and 25%, respectively. By univariate analysis, 3-year OS was significantly influenced by histology (47% for embryonal v 34% for all others, P =.026) and increasing number of metastatic sites (P =.028). By multivariate analysis, the presence of two or fewer metastatic sites was the only significant predictor (P =.007 and.006, respectively). The combination of embryonal histology with two or fewer metastatic sites identified a subgroup with 3-year FFS of 40% and OS of 47%. CONCLUSION Children with group IV RMS treated on the IRS-IV study had improved OS and FFS if they had two or fewer metastatic sites and embryonal histology. This favorable subset of patients has outcomes approaching those observed in selected patients with localized, nonmetastatic disease. Thus, these patients might not be appropriate candidates for regimens that include experimental agents with substantial toxicities or unproven antitumor activity.

Rhabdomyosarcoma and undifferentiated sarcoma in the first two decades of life : a selective review of intergroup rhabdomyosarcoma study group experience and rationale for intergroup rhabdomyosarcoma study V

Purpose To review the importance of prognostic factors in developing new protocols for children with rhabdomyosarcoma (RMS). Patients and Methods Four studies conducted by the Intergroup Rhabdomyosarcoma Study (IRS) Group from 1972 through 1991. Results Favorable prognostic factors are: (1) undetectable distant metastases at diagnosis; (2) primary sites in the orbit and nonparameningeal head/neck and genitourinary nonbladder/prostate regions; (3) grossly complete surgical removal of localized tumor at the time of diagnosis; (4) embryonal/botryoid histology; (5) tumor size ≤5 cm; and (6) age younger than 10 years at diagnosis. The IRS-V protocols are risk-based and refine therapy by reducing exposure to cyclophosphamide and radiation therapy (XRT) in patients at low risk while adding new, active agents such as topotecan or irinotecan to the standard therapy of vincristine, actinomycin D, and cyclophosphamide (VAC) plus XRT for patients with unfavorable histology or advanced disease. Collection of biologic specimens from patients with newly diagnosed disease continues to identify other factors that may distinguish patients with favorable features from those who need more intensive therapy. A new protocol that takes into account their previous treatment is needed for patients with recurrent disease. This program (being planned) does not include bone marrow/stem cell reconstitution because this strategy has thus far failed to improve survival rates of patients with metastases at diagnosis. Conclusion Better understanding of biologic differences and new, active agents are needed to improve outcome of patients with unfavorable features at presentation.

Germline Mutations in Predisposition Genes in Pediatric Cancer

BACKGROUND The prevalence and spectrum of predisposing mutations among children and adolescents with cancer are largely unknown. Knowledge of such mutations may improve the understanding of tumorigenesis, direct patient care, and enable genetic counseling of patients and families. METHODS In 1120 patients younger than 20 years of age, we sequenced the whole genomes (in 595 patients), whole exomes (in 456), or both (in 69). We analyzed the DNA sequences of 565 genes, including 60 that have been associated with autosomal dominant cancer-predisposition syndromes, for the presence of germline mutations. The pathogenicity of the mutations was determined by a panel of medical experts with the use of cancer-specific and locus-specific genetic databases, the medical literature, computational predictions, and second hits identified in the tumor genome. The same approach was used to analyze data from 966 persons who did not have known cancer in the 1000 Genomes Project, and a similar approach was used to analyze data from an autism study (from 515 persons with autism and 208 persons without autism). RESULTS Mutations that were deemed to be pathogenic or probably pathogenic were identified in 95 patients with cancer (8.5%), as compared with 1.1% of the persons in the 1000 Genomes Project and 0.6% of the participants in the autism study. The most commonly mutated genes in the affected patients were TP53 (in 50 patients), APC (in 6), BRCA2 (in 6), NF1 (in 4), PMS2 (in 4), RB1 (in 3), and RUNX1 (in 3). A total of 18 additional patients had protein-truncating mutations in tumor-suppressor genes. Of the 58 patients with a predisposing mutation and available information on family history, 23 (40%) had a family history of cancer. CONCLUSIONS Germline mutations in cancer-predisposing genes were identified in 8.5% of the children and adolescents with cancer. Family history did not predict the presence of an underlying predisposition syndrome in most patients. (Funded by the American Lebanese Syrian Associated Charities and the National Cancer Institute.).

Biology and therapy of pediatric rhabdomyosarcoma.

PURPOSE To review key developments in biology and therapy of rhabdomyosarcoma (RMS) since the early 1970s. PATIENTS AND METHODS The literature regarding biology, therapy, and late effects of therapy through March 1995 was reviewed. RESULTS The two major histiotypes, embryonal and alveolar, are characterized by specific genetic abnormalities that provide clues to mechanisms of tumor induction. Alveolar tumors, for example, often possess a chromosomal translocation [t(2;13)(q35;q14)] that fuses the PAX3 gene in band 2q35 with the FKHR gene in band 13q14, creating a novel chimeric protein that could inappropriately activate normal targets of the PAX3 gene product, thereby contributing to tumorigenesis. Recognition of prognostically important patient groups primarily identified by tumor extent, site, and histology, and development of effective risk-based multimodal therapy in randomized trials, have increased long-term survival in RMS from 25% in 1970 to more than 70% in current studies. The most significant recent gain in therapeutic results was realized in patients with gross residual tumor after biopsy. CONCLUSION Contemporary risk-based therapy cures more than two thirds of children with RMS while minimizing acute and late effects. Increased dose-intensity of known effective agents with hematopoietic growth factor support, new agents, and hyperfractionated irradiation are being evaluated in hopes of further improving therapy. Recent discovery of novel genetic features in this tumor should lead to better methods of diagnosis and risk assessment, and ultimately to identification of molecular targets for specific treatment.

Direct Translation of a Protracted Irinotecan Schedule From a Xenograft Model to a Phase I Trial in Children

PURPOSE In a preclinical model of neuroblastoma, administration of irinotecan daily 5 days per week for 2 consecutive weeks ([qd x 5] x 2) resulted in greater antitumor activity than did a single 5-day course with the same total dose. We evaluated this protracted schedule in children. PATIENTS AND METHODS Twenty-three children with refractory solid tumors were enrolled onto a phase I study. Cohorts received irinotecan by 1-hour intravenous infusion at 20, 24, or 29 mg/m(2) (qd x 5) x 2 every 21 days. RESULTS The 23 children (median age, 14.1 years; median prior regimens, two) received 84 courses. Predominant diagnoses were neuroblastoma (n = 5), osteosarcoma (n = 5), and rhabdomyosarcoma (n = 4). The dose-limiting toxicity was grade 3/4 diarrhea and/or abdominal cramps in six of 12 patients treated at 24 mg/m(2), despite aggressive use of loperamide. The maximum-tolerated dose (MTD) on this schedule was 20 mg/m(2)/d. Five patients had partial responses and 16 had disease stabilization. On day 1, the median systemic exposure to SN-38 (the active metabolite of irinotecan) at the MTD was 106 ng-h/mL (range, 41 to 421 ng-h/mL). CONCLUSION This protracted schedule is well tolerated in children. The absence of significant myelosuppression and encouraging clinical responses suggest compellingly that irinotecan be further evaluated in children using the (qd x 5) x 2 schedule, beginning at a dose of 20 mg/m(2). These results imply that data obtained from xenograft models can be effectively integrated into the design of clinical trials.

Analysis of Prognostic Factors in Patients With Nonmetastatic Rhabdomyosarcoma Treated on Intergroup Rhabdomyosarcoma Studies III and IV: The Children's Oncology Group

PURPOSE The outcome for localized rhabdomyosarcoma (RMS) or undifferentiated sarcoma (UDS) is affected by age, histology, primary anatomic site, extent of disease, and therapy. PATIENTS AND METHODS We evaluated patient and disease characteristics for their ability to predict outcome for patients with nonmetastatic RMS or UDS treated on Intergroup Rhabdomyosarcoma Study (IRS) -III (1984 to 1991) or IRS-IV (1991 to 1997). RESULTS The estimated 5-year failure-free survival (FFS) rate was 90% for patients with embryonal RMS (ERMS) stage 1, group I or IIa; stage 2, group I; or group III orbit. The estimated 5-year FFS rate was 87% for patients with ERMS stage 1, group IIb or IIc; stage 1, group III nonorbit; stage 2, group II; and stage 3, group I or II; and 73% for patients with ERMS stage 2 or 3, group III. The estimated 5-year FFS rate was poor for patients with stage 2 or 3, group III ERMS with invasive (T2) tumors who were age younger than 1 year or 10 years or older (56%) and patients with stage 2 or 3, group III extremity primary tumors (43%). Overall, outcomes for patients with alveolar RMS (ARMS) or UDS were worse than for patients with ERMS. However, the 5-year FFS rate was good for patients with ARMS/UDS at favorable sites with group I or II (80%) or group III (76%) disease. The FFS rate was poorer for patients with ARMS/UDS at unfavorable sites with group I or II (66%) or group III (45%) disease. The estimated 5-year FFS rate was 31% for patients with group III ARMS/UDS at unfavorable sites with regional lymph node disease, which is similar to metastatic RMS. CONCLUSION Patient and disease characteristics identify distinct subsets with different outcomes, allowing the Soft Tissue Sarcoma Committee of the Childrens Oncology Group to refine risk-adapted therapy assignment.

Recurrent somatic structural variations contribute to tumorigenesis in pediatric osteosarcoma.

Pediatric osteosarcoma is characterized by multiple somatic chromosomal lesions, including structural variations (SVs) and copy number alterations (CNAs). To define the landscape of somatic mutations in pediatric osteosarcoma, we performed whole-genome sequencing of DNA from 20 osteosarcoma tumor samples and matched normal tissue in a discovery cohort, as well as 14 samples in a validation cohort. Single-nucleotide variations (SNVs) exhibited a pattern of localized hypermutation called kataegis in 50% of the tumors. We identified p53 pathway lesions in all tumors in the discovery cohort, nine of which were translocations in the first intron of the TP53 gene. Beyond TP53, the RB1, ATRX, and DLG2 genes showed recurrent somatic alterations in 29%-53% of the tumors. These data highlight the power of whole-genome sequencing for identifying recurrent somatic alterations in cancer genomes that may be missed using other methods.

R1507, a Monoclonal Antibody to the Insulin-Like Growth Factor 1 Receptor in Patients With Recurrent or Refractory Ewing Sarcoma Family of Tumors: Results of a Phase II Sarcoma Alliance for Research through Collaboration Study

PURPOSE The type 1 insulin-like growth factor 1 receptor (IGF-1R) has been implicated in the pathogenesis of the Ewing sarcoma family of tumors (ESFT). We conducted a multicenter phase II study of the fully human IGF-1R monoclonal antibody R1507 in patients with recurrent or refractory ESFT. PATIENTS AND METHODS Patients ≥ 2 years of age with refractory or recurrent ESFT received R1507 at doses of 9 mg/kg intravenously one a week or 27 mg/kg intravenously every three weeks. Response was measured by using WHO criteria. Tumor imaging was performed every 6 weeks for 24 weeks and then every 12 weeks. RESULTS From December 2007 through April 2010, 115 eligible patients from 31 different institutions were enrolled. The median age was 25 years (range, 8 to 78 years). The location of the primary tumor was bone in 57% of patients and extraskeletal in 43% of patients. A total of 109 patients were treated with R1507 9 mg/kg/wk, and six patients were treated with 27 mg/kg/3 wk. The overall complete response/partial response rate was 10% (95% CI, 4.9% to 16.5%). The median duration of response was 29 weeks (range, 12 to 94 weeks), and the median overall survival was 7.6 months (95% CI, 6 to 9.7 months). Ten of 11 responses were observed in patients who presented with primary bone tumors (P = .016). The most common adverse events of grades 3 to 4 were pain (15%), anemia (8%), thrombocytopenia (7%), and asthenia (5%). CONCLUSION R1507 was a well-tolerated agent that had meaningful and durable benefit in a subgroup of patients with ESFT. The identification of markers that are predictive of a benefit is necessary to fully capitalize on this approach.

Association of Age at Diagnosis and Genetic Mutations in Patients With Neuroblastoma

CONTEXT Neuroblastoma is diagnosed over a wide age range from birth through young adulthood, and older age at diagnosis is associated with a decline in survivability. OBJECTIVE To identify genetic mutations that are associated with age at diagnosis in patients with metastatic neuroblastoma. DESIGN, SETTING, AND PATIENTS Whole genome sequencing was performed on DNA from diagnostic tumors and their matched germlines from 40 patients with metastatic neuroblastoma obtained between 1987 and 2009. Age groups at diagnosis included infants (0-<18 months), children (18 months-<12 years), and adolescents and young adults (≥12 years). To confirm the findings from this discovery cohort, validation testing using tumors from an additional 64 patients obtained between 1985 and 2009 also was performed. Formalin-fixed, paraffin-embedded tumor tissue was used for immunohistochemistry and fluorescence in situ hybridization. Telomere lengths were analyzed using whole genome sequencing data, quantitative polymerase chain reaction, and fluorescent in situ hybridization. MAIN OUTCOME MEASURE Somatic recurrent mutations in tumors from patients with neuroblastoma correlated with the age at diagnosis and telomere length. RESULTS In the discovery cohort (n = 40), mutations in the ATRX gene were identified in 100% (95% CI, 50%-100%) of tumors from patients in the adolescent and young adult group (5 of 5), in 17% (95% CI, 7%-36%) of tumors from children (5 of 29), and 0% (95% CI, 0%-40%) of tumors from infants (0 of 6). In the validation cohort (n = 64), mutations in the ATRX gene were identified in 33% (95% CI, 17%-54%) of tumors from patients in the adolescent and young adult group (9 of 27), in 16% (95% CI, 6%-35%) of tumors from children (4 of 25), and in 0% (95% CI, 0%-24%) of tumors from infants (0 of 12). In both cohorts (N = 104), mutations in the ATRX gene were identified in 44% (95% CI, 28%-62%) of tumors from patients in the adolescent and young adult group (14 of 32), in 17% (95% CI, 9%-29%) of tumors from children (9 of 54), and in 0% (95% CI, 0%-17%) of tumors from infants (0 of 18). ATRX mutations were associated with an absence of the ATRX protein in the nucleus and with long telomeres. CONCLUSION ATRX mutations were associated with age at diagnosis in children and young adults with stage 4 neuroblastoma. TRIAL REGISTRATION clinicaltrials.gov Identifier: NCT00588068.