Intraoperative radiation therapy for pediatric sarcomas and other solid tumors

PURPOSE

To evaluate local failure (LF) and toxicity after intraoperative radiation therapy (IORT) in pediatric solid tumors (ST).

METHODS

A single-institution retrospective study of 96 pediatric patients (108 applications) with ST treated from 1995 to 2022 with IORT. LF was calculated via cumulative incidence function and overall survival (OS) by Kaplan-Meier method, both from the day of surgery.

RESULTS

Median age at time of IORT was 8 years (range: 0.8-20.9 years). Median follow-up for all patients and surviving patients was 16 months and 3 years, respectively. The most common histologies included rhabdomyosarcoma (n = 42), Ewing sarcoma (n = 10), and Wilms tumor (n = 9). Most (95%) received chemotherapy, 37% had prior external beam radiation therapy to the site of IORT, and 46% had a prior surgery for tumor resection. About half (54%) were treated with upfront IORT to the primary tumor due to difficult circumstances such as very young age or challenging anatomy. The median IORT dose was 12 Gy (range: 4-18 Gy), and median area treated was 24 cm2 (range: 2-198 cm2). The cumulative incidence of LF was 17% at 2 years and 23% at 5 years. Toxicity from IORT was reasonable, with postoperative complications likely related to IORT seen in 15 (16%) patients.

CONCLUSION

Our study represents the largest and most recent analysis of efficacy and safety of IORT in pediatric patients with ST. Less than one quarter of all patients failed locally with acceptable toxicities. Overall, IORT is an effective and safe technique to achieve local control in patients with challenging circumstances.

Intraoperative Radiation Therapy for Relapsed or Refractory High-Risk Neuroblastoma: A 27-Year Experience

PURPOSE

To evaluate outcomes after intraoperative radiation therapy (IORT) in high-risk neuroblastoma (NB), including local control, overall survival, and toxicity.

METHODS AND MATERIALS

This was a single institution retrospective study of 92 pediatric patients with NB treated with IORT from 1995 to 2022. Each IORT application was considered a separate event for a total of 110 sites treated. Local failure was calculated using the cumulative incidence function and survival by Kaplan-Meier method from the day of surgery.

RESULTS

All patients had high-risk relapsed or treatment refractory disease. Median age was 6 years (range, 2-34 years). Median follow-up for all patients and surviving patients was 16 months and 4 years, respectively. All patients previously received chemotherapy, 93% had prior external beam radiation therapy to the site of IORT (median dose, 21.6 Gy; range, 10-36 Gy), and 94% had a prior surgery for tumor resection. The median IORT dose was 12 Gy (range, 8-18 Gy) and median area treated was 18 cm2 (range, 2.5-60 cm2). The cumulative incidence of local failure was 23% at 2 years and 29% at 5 years. The overall survival (OS) was 44% at 2 years and 29% at 5 years. Local failure after IORT was associated with worse OS (hazard ratio, 1.74; 95% CI, 1.07-2.84; P = .0267). Toxicity from IORT was rare, with postoperative complications likely related to IORT seen in 7 (8%) patients.

CONCLUSIONS

Our study represents the largest, most recent analysis of the efficacy and safety of IORT in patients with relapsed or refractory NB. Less than one-third of patients failed locally at 5 years, and achieving local control affected overall survival. Minimal toxicities directly related to IORT were observed. Overall, IORT is an effective and safe technique to achieve local control in high-risk relapsed or refractory neuroblastoma.

Posttreatment complications in pediatric cervical neuroblastoma: A retrospective case series at a tertiary cancer center

BACKGROUND

Neuroblastomas rarely occur as primary tumors in the cervical region. Therefore, very little has been reported regarding treatment strategies, complications, and outcomes of these cervical neuroblastomas. The goal of this study is to review the presentation, management, and outcomes of all primary cervical pediatric neuroblastoma cases at a single tertiary care center.

METHODS

A retrospective cohort review of all neuroblastoma patients treated at a single center were performed. All patients with primary cervical neuroblastoma were reviewed for demographic information, tumor characteristics, treatment, and outcomes.

RESULTS

Thirty (1.8%) patients were found to have undergone treatment for cervical neuroblastoma tumors diagnosed on average at 2.1 years old. Most presented with a swollen neck/palpable mass ± Horner's syndrome. Based on features including tumor staging, N-myc proto-oncogene protein (MYCN) amplification status, histology, most were deemed intermediate or high risk. Treatment strategies centered around chemotherapeutic regimens with surgery when possible as well as various adjuvant treatments including radiation therapy, immunotherapy, bone marrow transplant, and a neuroblastoma vaccine. Ten (33.3%) of patients experienced treatment-related complications and four (13.3%) died as a result of their disease progression. All four patients were high-risk patients, two of which had MYCN amplification.

CONCLUSION

Cervical neuroblastomas generally have favorable outcomes. These tumors can be treated effectively with chemotherapy and surgical intervention with various adjuvant therapies. MYCN amplification and higher stage disease presentation contribute to worse outcomes.

Stage 4N neuroblastoma before and during the era of anti-GD2 immunotherapy

Patients with stage 4N neuroblastoma (distant metastases limited to lymph nodes) stand out as virtually the only survivors of high-risk neuroblastoma (HR-NB) before myeloablative therapy (MAT) and immunotherapy with anti-GD2 monoclonal antibodies (mAbs) became standard. Because no report presents more recent results with 4N, we analyzed our large 4N experience. All 51 pediatric 4N patients (<18 years old) diagnosed 1985 to 2021 were reviewed. HR-NB included MYCN-nonamplified 4N diagnosed at age ≥18 months and MYCN-amplified 4N. Among 34 MYCN-nonamplified high-risk patients, 20 are relapse-free 1.5+ to 37.5+ (median 12.5+) years post-diagnosis, including 13 without prior MAT and 5 treated with little (1 cycle; n = 2) or no mAb (n = 3), while 14 patients (7 post-MAT, 8 post-mAbs) relapsed (all soft tissue). Of 15 MYCN-amplified 4N patients, 7 are relapse-free 2.1+ to 26.4+ (median 11.6+) years from the start of chemotherapy (all received mAbs; 3 underwent MAT) and 4 are in second remission 4.2+ to 21.8+ years postrelapse (all soft tissue). Statistical analyses showed no significant association of survival with either MAT or mAbs for MYCN-nonamplified HR-NB; small numbers prevented these analyses for MYCN-amplified patients. The two patients with intermediate-risk 4N (14-months-old) are relapse-free 7+ years postresection of primary tumors; distant disease spontaneously regressed. The natural history of 4N is marked by NB confined to soft tissue without early relapse in bones or bone marrow, where mAbs have proven efficacy. These findings plus curability without MAT, as seen elsewhere and at our center, support consideration of treatment reduction for MYCN-nonamplified 4N.

Critical elements of pediatric neuroblastoma surgery

Neuroblastoma (NB) is the most common solid extracranial malignancy of childhood with an incidence of 1 per 100,000 in the United States compromising approximately 10 % of childhood cancer. Unfortunately, patients with high-risk NG continue to have long-term survival less than 50 %. Both Children's Oncology Group and the International Society of Paediatric Oncology have demonstrated the important role of surgery in the treatment of high-risk NB. Herein, we compose the results of an extensive literature review as well as expert opinion from leaders in pediatric surgical oncology, to present the critical elements of effective surgery for high-risk neuroblastoma.

High-Dose-Rate Brachytherapy for Vaginal Rhabdomyosarcoma (RMS): Lessons Learned at a Single Institution

PURPOSE/OBJECTIVE(S)

Botryoid RMS is a rare pediatric tumor most commonly arising within the vaginal wall of girls under age three. Most patients are successfully treated with low-risk chemotherapy protocols but local treatment is required to minimize risk of local relapse. Intravaginal brachytherapy is an effective local therapy that can minimize sequelae in these very young patients.

MATERIALS/METHODS

We reviewed records of all patients with RMS who received intravaginal high-dose-rate brachytherapy from 2010-2022 at a single institution. All were treated with multiagent chemotherapy with or without minor surgical procedures, and had no gross disease prior to intravaginal brachytherapy. All patients underwent CT simulation under anesthesia and optimal-sized cylindrical applicators were chosen based on patient anatomy.

RESULTS

Twelve girls, median age 23 months (range 3-33), were treated with daily anesthesia. All were Stage 1 and 92% had Group III disease. A single patient had Group IIA disease based on up-front resection. Early in the series, 5 patients received 21 Gy in 7 fractions according to COG protocol guidelines. Subsequent patients received higher doses of 28-30 Gy in 7-10 fractions. Custom sized cylinders were used with diameters ranging from 1.2-1.6 cm and dose was prescribed to a median depth of 3 mm. Median mean dose to the rectum, bladder, uterus, and bilateral ovaries was 8.7 Gy, 7.2 Gy, 6.9 Gy, and 5.0 Gy, respectively. Median follow-up was 4 years (range 1-10). No acute or late side effects have occurred. At follow-up, three girls were of pubescent age, all three exhibited signs of puberty and two had reached menarche. Three girls (25%) suffered local relapse at a median of 15 months (range 5-16 months) after brachytherapy. One-year and five-year local control rates were 92% (95% CI 54-99%) and 70% (95% CI 32-89%), respectively. All relapses were in patients receiving 21 Gy and two were beyond full dose coverage of brachytherapy at the introitus and in the uterus. Subsequent patients receiving higher doses and full coverage of the vagina have had no local failures. Two of three patients who failed were cured with salvage therapy resulting in one-year and five-year overall survival rates of 100% and 86% (95% CI 33-98%), respectively.

CONCLUSION

Intravaginal high-dose-rate brachytherapy is an excellent option for local control of vaginal RMS with fewer long-term risks than external beam proton therapy or radical surgery. A dose of 28 Gy in 7 fractions prescribed to the entire vagina is necessary for optimal prevention of relapse. Longer follow-up is needed to confirm preservation of ovarian, reproductive, and sexual function.

Intraoperative Radiation Therapy for Pediatric Patients: A 25 Year Experience

PURPOSE/OBJECTIVE(S)

To assess outcomes after intra-operative radiation therapy (IORT) in pediatric patients, including local control, overall survival, and toxicity.

MATERIALS/METHODS

Single institution retrospective study of 184 pediatric patients treated with IORT from 1995-2022. Each IORT application was considered a separate event for a total of 213 sites treated. Local failure was calculated using the cumulative incidence function and survival by Kaplan-Meier method from the day of surgery. Median follow up for all patients was 14 months while median follow up for surviving patients was 3 years.

RESULTS

Median patient age was 6 years (range 9 months to 21 years) and half were male. Patients were generally high risk with 76% having relapsed or refractory disease. Tumor types included neuroblastoma (n = 88), soft tissue sarcoma (n = 69), Wilms tumor (n = 11), and other solid tumors (n = 24). The majority (97%) of patients had prior chemotherapy, 69% had at least one prior attempt at resection, and 65% had prior external beam radiation to the site of IORT. Location of IORT included the retroperitoneum (n = 99), anterior abdominal wall (n = 14), pelvic region (n = 49), chest and thorax (n = 36), head (n = 5), neck (n = 7), and axilla/shoulder (n = 3), with a median dose of 12 Gy (range 4 to 18 Gy). Overall survival was 47% and 32% at 2 and 5 years respectively. Rates of local failure were 20% and 26% at 2 and 5 years. Local failure had a significant impact on overall survival (p = 0.009). Analyzing specific tumor types at 2 years, the rate of local failure and overall survival were 22% and 57% for soft tissue sarcomas, 23% and 39% for neuroblastoma, and 10% and 60% for Wilms tumor. Direct toxicity from IORT was rare, however there were several cases of surgical complications where a potential contribution from IORT could not be ruled out. The most common complications included abscesses in the surgical field, fistula or stricture development, and hydronephrosis. There were no post-operative mortalities related to IORT.

CONCLUSION

Our study represents the largest scale analysis of efficacy and safety of IORT in patients with pediatric solid tumors. Less than one third of patients failed locally at 5 years. Achieving local control impacted overall survival, emphasizing the importance of local control in these patients. Minimal radiation related toxicities were observed. Overall, IORT is an effective technique to achieve local control in children with high-risk solid tumors.

Clonal evolution during metastatic spread in high-risk neuroblastoma

Patients with high-risk neuroblastoma generally present with widely metastatic disease and often relapse despite intensive therapy. As most studies to date focused on diagnosis-relapse pairs, our understanding of the genetic and clonal dynamics of metastatic spread and disease progression remain limited. Here, using genomic profiling of 470 sequential and spatially separated samples from 283 patients, we characterize subtype-specific genetic evolutionary trajectories from diagnosis through progression and end-stage metastatic disease. Clonal tracing timed disease initiation to embryogenesis. Continuous acquisition of structural variants at disease-defining loci (MYCN, TERT, MDM2-CDK4) followed by convergent evolution of mutations targeting shared pathways emerged as the predominant feature of progression. At diagnosis metastatic clones were already established at distant sites where they could stay dormant, only to cause relapses years later and spread via metastasis-to-metastasis and polyclonal seeding after therapy.

Abstract 1516: Bulk and spatial single-cell transcriptomic characterization of fibrolamellar hepatocellular carcinoma

Fibrolamellar Hepatocellular Carcinoma (FLC) is a rare liver cancer affecting adolescents and young adults, with no gender or ethnicity predilection and without history of underlying viral hepatitis, cirrhosis, or other known risk factors. Almost all FLC patients present a somatic heterozygous deletion in chromosome 19p13.12, DNAJB1::PRKACA, which is sufficient to drive FLC in mice. A few studies comparing FLC tumors with adjacent non-transformed liver (normal) samples revealed many transcriptional differences. However, there were done in very small datasets and analyzed using different bioinformatic methods, resulting in just 18-47% agreement between them. This study aims to comprehensively characterize the transcriptome of FLC at bulk and spatial single-cell resolution.

The whole transcriptome of 109 FLC frozen patient samples, the largest RNA-seq dataset of FLC to date, was sequenced using different library preparation and ribosomal depletion methods. Only paired tumor and normal tissue samples resected from the same patient were used and divided into two groups: exploration (3 datasets, 67 samples) and testing (2 datasets, 17 samples). Additionally, as external validation datasets, RNA-seq samples from previously published studies were collected, including Sorenson et al. (FLC: 26, normal: 9, paired: 8), the TCGA-LIHC study (FLC: 6, normal: 1, paired: 1), Hirsch et al. (FLC: 15, normal: 3, paired: 0) and Francisco et al. (FLC: 27, normal: 10, paired: 9). All were reanalyzed using state-of-the-art bioinformatic methods: mapped to the Human Genome GRCh38.103 and transcripts quantified using Salmon 1.6.0, unsupervised clustering exploration using PCA, tSNE and UMAP, differential expression calculated using DESeq2 1.28.1, and checking for detectability and consistency among datasets. We found 857 up- and 988 down-regulated genes presenting the same dysregulation in the exploration datasets and confirmed in the testing and external datasets. We call these genes the transcriptional FLC signature.

The FLC signature was further characterized by comparing it with the genes differentially expressed in other liver cancers: hepatocellular carcinoma (41 paired samples), hepatoblastoma (22 paired samples), and cholangiocarcinoma (27 paired samples). We found 276 up- and 352 down-regulated genes altered in other liver cancers as well as FLC, but 156 up- and 68 down-regulated only in FLC. The 112 genes with the strongest dysregulation (56 up and 56 down) were used for a MERFISH screening, providing for the first time a single-cell spatial transcriptomic characterization of FLC. This showed clear differential expression patterns in tumor, normal, stromal, and infiltrating immune cells, allowing the identification of how different cell types contribute to the transcriptional FLC signature.

Citation Format: David Requena, Aldhair Medico, Luis F. Soto, Mahsa Shirani, James A. Saltsman, Gadi Lalazar, Michael P. LaQuaglia, Sanford M. Simon. Bulk and spatial single-cell transcriptomic characterization of fibrolamellar hepatocellular carcinoma [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 1516.

Implications of Tumor Characteristics and Treatment Modality on Local Recurrence and Functional Outcomes in Children With Chest Wall Sarcoma: A Pediatric Surgical Oncology Research Collaborative Study

OBJECTIVE

To determine the impact of tumor characteristics and treatment approach on (1) local recurrence, (2) scoliosis development, and (3) patient-reported quality of life in children with sarcoma of the chest wall.

SUMMARY OF BACKGROUND DATA

Children with chest wall sarcoma require multimodal therapy including chemotherapy, surgery, and/or radiation. Despite aggressive therapy which places them at risk for functional impairment and scoliosis, these patients are also at significant risk for local recurrence.

METHODS

A multi-institutional review of 175 children (median age 13 years) with chest wall sarcoma treated at seventeen Pediatric Surgical Oncology Research Collaborative institutions between 2008 and 2017 was performed. Patient-reported quality of life was assessed prospectively using PROMIS surveys.

RESULTS

The most common diagnoses were Ewing sarcoma (67%) and osteosarcoma (9%). Surgical resection was performed in 85% and radiation in 55%. A median of 2 ribs were resected (interquartile range = 1-3), and number of ribs resected did not correlate with margin status ( P = 0.36). Local recurrence occurred in 23% and margin status was the only predictive factor(HR 2.24, P = 0.039). With a median follow-up of 5 years, 13% developed scoliosis (median Cobb angle 26) and 5% required corrective spine surgery. Scoliosis was associated with posteriorrib resection (HR 8.43; P= 0.003) and increased number of ribs resected (HR 1.78; P = 0.02). Overall, patient-reported quality of life is not impaired after chest wall tumor resection.

CONCLUSIONS

Local recurrence occurs in one-quarter of children with chest wall sarcoma and is independent of tumor type. Scoliosis occurs in 13% of patients, but patient-reported quality of life is excellent.

Advances in the treatment of pediatric solid tumors: A 50-year perspective

In the United States, more than 10 000 cancers occur annually in children aged 0-14 years, and more than 5000 in adolescents aged 15-19. In the last 50 years, significant advances have been made in imaging, molecular pathology, stage and risk assessment, surgical approach, multidisciplinary treatment, and survival for pediatric solid tumors (particularly neuroblastoma, Wilms tumor, rhabdomyosarcoma, and hepatoblastoma). Moreover, the molecular driver for fibrolamellar hepatocellular carcinoma, which occurs in adolescence and young adulthood, has been identified.

Human liver organoids for disease modeling of fibrolamellar carcinoma

Fibrolamellar carcinoma (FLC) is a rare, often lethal, liver cancer affecting adolescents and young adults, for which there are no approved therapeutics. The development of therapeutics is hampered by a lack of in vitro models. Organoids have shown utility as a model system for studying many diseases. In this study, tumor tissue and the adjacent non-tumor liver were obtained at the time of surgery. The tissue was dissociated and grown as organoids. We developed 21 patient-derived organoid lines: 12 from metastases, three from the liver tumor and six from adjacent non-tumor liver. These patient-derived FLC organoids recapitulate the histologic morphology, immunohistochemistry, and transcriptome of the patient tumor. Patient-derived FLC organoids were used in a preliminary high-throughput drug screen to show proof of concept for the identification of therapeutics. This model system has the potential to improve our understanding of this rare cancer and holds significant promise for drug testing and development.

Abstract 704: Development of a patient-derived xenograft (PDX) modeling program to enable pediatric precision medicine

Background: Recapitulation of the full spectrum of genomic changes driving patient tumors have resulted in increased use of patient-derived xenograft (PDX) models in studies of basic cancer biology and preclinical drug development. Given the translational potential of PDXs and limited availability of pediatric cancer models, we established a PDX program to expand the existing collection of pediatric PDXs in the community and enable pre- and post-clinical studies.

Methods: PDX generation requests were integrated into clinical workflows to maximize identification of eligible patients for informed consent and tissue collection at Memorial Sloan Kettering Cancer Center. Methodologies for tissue procurement and cryopreservation were optimized to facilitate implantation into host immunodeficient mice and enable multi-institutional tissue exchange for model building. A bioinformatics pipeline was established to allow molecular validation of engrafted PDXs using a next-generation targeted gene panel (MSK-IMPACT) evaluating concordance based on acquired mutations, copy number alterations and clonal structure.

Results: Between November 2016 - October 2021, 379 PDX models were developed (265 distinct models) representing 69 discrete diagnoses. Sarcoma represents the most common model type (50 discrete osteosarcoma, 20 desmoplastic small round cell tumor, 14 Ewing sarcoma, 24 rhabdomyosarcoma, 2 CIC/DUX4 and 2 BCOR-rearranged sarcoma) followed by neuroblastoma (n=35), leukemia (n=44), and Wilms tumor (n=15). While the majority of PDXs were established from recurrent or metastatic tissue, 7 paired diagnostic/pre-therapy and post-therapy or relapse models were generated. Genomic characterization of PDXs demonstrate excellent concordance and recapitulation of single nucleotide variants (90%), structural (88%) and copy number variants (94%) between patient tumor and matched PDX. Discrepancies between matched patient/PDX pairs are due to sub-clonal heterogeneity in source tumors with clonal outgrowth in the PDX. Analysis of serial PDX passages also demonstrate stable recapitulation of the genomic profile. Establishment of a diverse PDX collection allowed preclinical evaluation of 10 targeted agents across a spectrum of pediatric tumors and provided the preclinical rationale for 3 investigator-initiated pediatric clinical trials.

Conclusions: Investment in the development of a phenotypically diverse and biologically faithful collection of pediatric PDX models enables the goals of precision medicine. Optimization of PDX workflows and methods has also enabled the development of a pediatric PDX consortium (PROXC - Pediatric Research in Oncology Xenografting Consortium) to further support the development of pre- and post-clinical studies for pediatric cancer.

Citation Format: Filemon S. Dela Cruz, Joseph G. McCarter, Daoqi You, Nancy Bouvier, Xinyi Wang, Kristina C. Guillan, Armaan H. Siddiquee, Katie B. Souto, Hongyan Li, Teng Gao, Dominik Glodzik, Daniel Diolaiti, Neerav N. Shukla, Joachim Silber, Umeshkumar K. Bhanot, Faruk Erdem Kombak, Diego F. Coutinho, Shanita Li, Juan E. Arango Ossa, Juan S. Medina-Martinez, Michael V. Ortiz, Emily K. Slotkin, Michael D. Kinnaman, Sameer F. Sait, Tara J. O'Donohue, Marissa Mattar, Maximiliano Meneses, Michael P. LaQuaglia, Todd E. Heaton, Justin T. Gerstle, Nicola Fabbri, Chelsey M. Burke, Irene M. Rodriquez-Sanchez, Christine A. Iacobuzio-Donahue, Julia L. Glade Bender, Ryan D. Roberts, Jason T. Yustein, Nino C. Rainusso, Brian D. Crompton, Elizabeth Stewart, Alejandro Sweet-Cordero, Leanne C. Sayles, Andrika D. Thomas, Michael H. Roehrl, Elisa de Stanchina, Elli Papaemmanuil, Andrew L. Kung. Development of a patient-derived xenograft (PDX) modeling program to enable pediatric precision medicine [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 704.

Survival and Scoliosis Following Resection of Chest Wall Tumors in Children and Adolescents: A Single-center Retrospective Analysis

OBJECTIVE

We reviewed our experience with pediatric chest wall tumors (CWTs) to identify variables associated with survival, scoliosis development, and need for corrective scoliosis surgery.

BACKGROUND

Chest wall neoplasms in children or adolescents are rare. Consequently, there are few large series that detail survival or quality of life indicators, like scoliosis.

METHODS

Medical records were reviewed for all chest wall resections for primary and metastatic CWT performed from October 1, 1986 to September 30, 2016 on patients 21 years or younger at diagnosis. Kaplan-Meier distributions were compared using the log-rank test. Variables correlated with survival, scoliosis development, or need for corrective surgeries were analyzed using competing-risk analysis.

RESULTS

Seventy-six cases [57 (75%) primary, 19 (25%) metastatic] were identified. Median age at diagnosis was 15.6 years (range: 0.5-21 years). Tumor types were Ewing sarcoma family tumors (54%), other soft tissue sarcomas (21%), osteosarcoma (11%), rhabdomyosarcoma (7%), and other (8%). A median of 3 (range: 1-5) contiguous ribs were resected. Surgical reconstruction included composite Marlex mesh and methyl-methacrylate, Gore-Tex, or primary closure in 57%, 28%, and 14% of procedures, respectively. Overall 5-year survival was 61% (95% confidence interval: 50%-75%). Scoliosis developed in 19 (25%) patients; 6 patients required corrective surgery. Variables associated with overall survival were the presence of metastatic disease at diagnosis, and whether the chest tumor itself was a primary or metastatic lesion. Younger age at chest wall resection was associated with the need for corrective surgery in patients who developed scoliosis.

CONCLUSIONS

Among pediatric and adolescent patients with CWTs, survival depends primarily on the presence of metastases. Age, type of chest wall reconstruction, and tumor size are not associated with scoliosis development. Among patients who develop scoliosis, younger patients are more likely to require corrective surgery.

Comprehensive Molecular Profiling of Desmoplastic Small Round Cell Tumor

Desmoplastic small round cell tumor (DSRCT) is characterized by the EWSR1-WT1 t(11;22) (p13:q12) translocation. Few additional putative drivers have been identified, and research has suffered from a lack of model systems. Next-generation sequencing (NGS) data from 68 matched tumor-normal samples, whole-genome sequencing data from 10 samples, transcriptomic and affymetrix array data, and a bank of DSRCT patient-derived xenograft (PDX) are presented. EWSR1-WT1 fusions were noted to be simple, balanced events. Recurrent mutations were uncommon, but were noted in TERT (3%), ARID1A (6%), HRAS (5%), and TP53 (3%), and recurrent loss of heterozygosity (LOH) at 11p, 11q, and 16q was identified in 18%, 22%, and 34% of samples, respectively. Comparison of tumor-normal matched versus unmatched analysis suggests overcalling of somatic mutations in prior publications of DSRCT NGS data. Alterations in fibroblast growth factor receptor 4 (FGFR4) were identified in 5 of 68 (7%) of tumor samples, whereas differential overexpression of FGFR4 was confirmed orthogonally using 2 platforms. PDX models harbored the pathognomic EWSR1-WT1 fusion and were highly representative of corresponding tumors. Our analyses confirm DSRCT as a genomically quiet cancer defined by the balanced translocation, t(11;22)(p13:q12), characterized by a paucity of secondary mutations but a significant number of copy number alterations. Against this genomically quiet background, recurrent activating alterations of FGFR4 stood out, and suggest that this receptor tyrosine kinase, also noted to be highly expressed in DSRCT, should be further investigated. Future studies of DSRCT biology and preclinical therapeutic strategies should benefit from the PDX models characterized in this study. IMPLICATIONS: These data describe the general quiescence of the desmoplastic small round cell tumor (DSRCT) genome, present the first available bank of DSRCT model systems, and nominate FGFR4 as a key receptor tyrosine kinase in DSRCT, based on high expression, recurrent amplification, and recurrent activating mutations.

Identification of Novel Therapeutic Targets for Fibrolamellar Carcinoma Using Patient Derived Xenografts and Direct from Patient Screening

To repurpose therapeutics for fibrolamellar carcinoma (FLC) we developed and validated patient-derived xenografts (PDX) from surgical resections. Most agents used clinically, and inhibitors of oncogenes overexpressed in FLC showed little efficacy on PDX. A high-throughput functional drug screen found primary and metastatic FLC were vulnerable to clinically available inhibitors of TOPO1 and HDAC, and to napabucasin. Napabucasin's efficacy was mediated through reactive oxygen species and inhibition of translation initiation, and specific inhibition of eIF4A was effective. The sensitivity of each PDX line inversely correlated with expression of the anti-apoptotic protein Bcl-xL, and inhibition of Bcl-xL synergized with other drugs. Screening directly on cells dissociated from patient resections validated these results. This demonstrates that a direct functional screen on patient tumors provides therapeutically informative data within a clinically useful time frame. Identifying these novel therapeutic targets and combination therapies is an urgent need, as effective therapeutics for FLC are currently unavailable.

Treatment of Pediatric Adrenocortical Carcinoma With Surgery, Retroperitoneal Lymph Node Dissection, and Chemotherapy: The Children's Oncology Group ARAR0332 Protocol

PURPOSE

Adrenocortical carcinoma (ACC) is a rare aggressive pediatric malignancy with distinct biology. Its treatment follows the principles developed for adults; pediatric-specific studies are scarce.

PATIENTS AND METHODS

Prospective single-arm risk-stratified interventional study. Study objectives were (1) to describe the outcome of patients with stage I ACC treated with adrenalectomy alone; (2) to describe the outcome of stage II patients (completely resected > 200 cc or > 100 g) treated with adrenalectomy and retroperitoneal lymph node dissection; and (3) to describe the outcome of patients with stage III or IV treated with mitotane and chemotherapy.

RESULTS

Between September 2006 and May 2013, 78 patients (77 eligible, 51 females) were enrolled. The 5-year event-free survival estimates for stages I (24 patients), II (15 patients), III (24 patients), and IV (14 patients) were 86.2%, 53.3%, 81%, and 7.1%, respectively. The corresponding 5-year overall survival estimates were 95.2%, 78.8%, 94.7%, and 15.6%, respectively. On univariate analysis, age, stage, presence of virilization, Cushing syndrome, or hypertension, germline TP53 status, and presence of a somatic ATRX mutation were associated with outcome. On multivariable analysis, only stage and age were significantly associated with outcome. The probabilities of mitotane and chemotherapy feasibility events were 10.5% and 31.6%, respectively.

CONCLUSION

Outcome for children with stage I ACC is excellent with surgery. Outcome for patients with stage II disease is inferior despite retroperitoneal lymph node dissection. Patients with stage III ACC have an excellent outcome combining surgery and chemotherapy. Patients with stage IV ACC are older and have a poor outcome; new treatments should be explored for this high-risk group. The combination of mitotane and chemotherapy as prescribed in ARAR0332 resulted in significant toxicity; one third of patients with advanced disease could not complete the scheduled treatment.

Therapeutic Potential of NTRK3 Inhibition in Desmoplastic Small Round Cell Tumor

PURPOSE

Desmoplastic small round cell tumor (DSRCT) is a highly lethal intra-abdominal sarcoma of adolescents and young adults. DSRCT harbors a t(11;22)(p13:q12) that generates the EWSR1-WT1 chimeric transcription factor, the key oncogenic driver of DSRCT. EWSR1-WT1 rewires global gene expression networks and activates aberrant expression of targets that together mediate oncogenesis. EWSR1-WT1 also activates a neural gene expression program.

EXPERIMENTAL DESIGN

Among these neural markers, we found prominent expression of neurotrophic tyrosine kinase receptor 3 (NTRK3), a druggable receptor tyrosine kinase. We investigated the regulation of NTRK3 by EWSR1-WT1 and its potential as a therapeutic target in vitro and in vivo, the latter using novel patient-derived models of DSRCT.

RESULTS

We found that EWSR1-WT1 binds upstream of NTRK3 and activates its transcription. NTRK3 mRNA is highly expressed in DSRCT compared with other major chimeric transcription factor-driven sarcomas and most DSRCTs are strongly immunoreactive for NTRK3 protein. Remarkably, expression of NTRK3 kinase domain mRNA in DSRCT is also higher than in cancers with NTRK3 fusions. Abrogation of NTRK3 expression by RNAi silencing reduces growth of DSRCT cells and pharmacologic targeting of NTRK3 with entrectinib is effective in both in vitro and in vivo models of DSRCT.

CONCLUSIONS

Our results indicate that EWSR1-WT1 directly activates NTRK3 expression in DSRCT cells, which are dependent on its expression and activity for growth. Pharmacologic inhibition of NTRK3 by entrectinib significantly reduces growth of DSRCT cells both in vitro and in vivo, providing a rationale for clinical evaluation of NTRK3 as a therapeutic target in DSRCT.

A Multicenter Randomized Three-Arm Phase II Study of (1) Everolimus, (2) Estrogen Deprivation Therapy (EDT) with Leuprolide + Letrozole, and (3) Everolimus + EDT in Patients with Unresectable Fibrolamellar Carcinoma

LESSONS LEARNED

FLC is a complex cancer with many implicated oncogenic pathways. Single or dual targeting does not appear to alter the natural history of the cancer, and novel therapeutics are needed. Estrogen deprivation therapy with letrozole and leuprolide, alone or in combination with the mTOR inhibitor, everolimus, did not demonstrate clinical activity in advanced fibrolamellar carcinoma. The study drugs were well tolerated when administered as single agents or in combination in this patient population. This study demonstrates that, despite the rarity of FLC, multicenter therapeutic clinical trials are feasible and support the value of this consortium.

BACKGROUND

Fibrolamellar carcinoma (FLC) is an uncommon malignancy in young people and is sometimes associated with pregnancy and oral contraceptive use. Immunohistochemical staining and genetic profiling of FLC tumor specimens have revealed aromatase overexpression. The overexpression of mTOR and S6 kinase has been noted in 25% of FLC. On the basis of interaction between estrogen and the PI3K/Akt/mTOR pathway, we hypothesized that suppression of estrogen and mTOR signaling could have antineoplastic activity in FLC.

METHODS

Patients were randomized to arm A (everolimus), arm B (letrozole/leuprolide; estrogen deprivation therapy [EDT]), or arm C (everolimus/letrozole/leuprolide). Upon disease progression, patients in arm A or B could proceed to part 2 (everolimus/letrozole/leuprolide). The primary endpoint was progression-free survival (PFS) at 6 months (PFS6) assessed using a Simon's minimax two-stage design, hypothesizing an improvement in PFS6 from 40% to 64% with the study regimen.

RESULTS

Twenty-eight patients were enrolled. An unplanned analysis was performed because of perceived concern for lack of efficacy. Stable disease was observed in 9 of 26 evaluable patients (35%). PFS6 was 0%. Median overall survival (OS) was 12.4 months (95% confidence interval [CI], 7.4-20.9) for the whole study cohort. Grade 3 adverse events in ≥10% of patients were nausea (11%), vomiting (11%), anemia (11%), elevated aspartate transaminase (AST; 32%), alanine transaminase (ALT; 36%), and alkaline phosphatase (14%). All 28 patients experienced an event for PFS outcome, and four deaths were due to disease progression.

CONCLUSION

Neither EDT nor mTOR inhibition improved outcomes in FLC. Other treatment strategies are needed.

B7H3-Directed Intraperitoneal Radioimmunotherapy With Radioiodinated Omburtamab for Desmoplastic Small Round Cell Tumor and Other Peritoneal Tumors: Results of a Phase I Study

PURPOSE

Desmoplastic small round cell tumor (DSRCT), a rare sarcoma of adolescents/young adults primarily involving the peritoneum, has a long-term survival of < 20% despite aggressive multimodality treatment. B7H3 is expressed on DSRCT cell surface, providing a target for antibody-based immunotherapy.

PATIENTS AND METHODS

In this phase I study, we evaluated the safety, pharmacokinetics, and biodistribution of intraperitoneal (IP) radioimmunotherapy (RIT) with the anti-B7H3 murine monoclonal antibody ¹³¹I-omburtamab in patients with DSRCT or other B7H3-expressing tumors involving the peritoneum. After thyroid blockade, patients received ¹³¹I-omburtamab as a single IP injection at escalated activities from 1.11 to 3.33/GBq/m². A prior tracer dose of IP 74 MBq¹²⁴I-omburtamab was used for radioimmuno-positron emission tomography imaging. Each injection was followed by IP saline infusion.

RESULTS

Fifty-two patients (48, three, and one with DSRCT, peritoneal rhabdomyosarcoma, and Ewing sarcoma, respectively) received IP ¹³¹I-omburtamab administered on an outpatient basis. Maximum tolerated dose was not reached; there were no dose-limiting toxicities. Major related adverse events were transient: grade 4 neutropenia (n = 2 patients) and thrombocytopenia (n = 1), and grade 1 (10%) and grade 2 (52%) pain lasting < 2 hours related to saline infusion. Hypothyroidism was not observed, and antidrug antibody was elicited in 5%. Mean (± SD) projected peritoneal residence time was 22.4 ± 7.9 hours. Mean projected absorbed doses for ¹³¹I-omburtamab based on ¹²⁴I-omburtamab dosimetry to normal organs were low and well within tolerable limits. More than 80% ¹³¹I remained protein bound in blood 66 hours after RIT. On the basis of peritoneal dose and feasibility for outpatient administration, the recommended phase II activity was established at 2.96 GBq/m². Patients with DSRCT receiving standard whole-abdominal radiotherapy after RIT did not experience unexpected toxicity.

CONCLUSION

IP RIT ¹³¹I-omburtamab was well tolerated with minimal toxicities. Radiation exposure to normal organs was low, making combination therapy with other anticancer therapies feasible.

A Human Organoid Model of Aggressive Hepatoblastoma for Disease Modeling and Drug Testing

Hepatoblastoma is the most common childhood liver cancer. Although survival has improved significantly over the past few decades, there remains a group of children with aggressive disease who do not respond to current treatment regimens. There is a critical need for novel models to study aggressive hepatoblastoma as research to find new treatments is hampered by the small number of laboratory models of the disease. Organoids have emerged as robust models for many diseases, including cancer. We have generated and characterized a novel organoid model of aggressive hepatoblastoma directly from freshly resected patient tumors as a proof of concept for this approach. Hepatoblastoma tumor organoids recapitulate the key elements of patient tumors, including tumor architecture, mutational profile, gene expression patterns, and features of Wnt/β-catenin signaling that are hallmarks of hepatoblastoma pathophysiology. Tumor organoids were successfully used alongside non-tumor liver organoids from the same patient to perform a drug screen using twelve candidate compounds. One drug, JQ1, demonstrated increased destruction of liver organoids from hepatoblastoma tumor tissue relative to organoids from the adjacent non-tumor liver. Our findings suggest that hepatoblastoma organoids could be used for a variety of applications and have the potential to improve treatment options for the subset of hepatoblastoma patients who do not respond to existing treatments.

Pancreaticoduodenectomy for the treatment of pancreatic neoplasms in children: A Pediatric Surgical Oncology Research Collaborative study

BACKGROUND

To better characterize short-term and long-term outcomes in children with pancreatic tumors treated with pancreaticoduodenectomy (PD).

METHODS

Patients 21 years of age or younger who underwent PD at Pediatric Surgical Oncology Collaborative (PSORC) hospitals between 1990 and 2017 were identified. Demographic, clinical information, and outcomes (operative complications, long-term pancreatic function, recurrence, and survival) were collected.

RESULTS

Sixty-five patients from 18 institutions with a median age of 13 years (4 months-22 years) and a median (IQR) follow-up of 2.8 (4.3) years were analyzed. Solid pseudopapillary tumor of the pancreas (SPN) was the most common histology. Postoperative complications included pancreatic leak in 14% (n = 9), delayed gastric emptying in 9% (n = 6), marginal ulcer in one patient, and perioperative (30-day) death due to hepatic failure in one patient. Pancreatic insufficiency was observed in 32% (n = 21) of patients, with 23%, 3%, and 6% with exocrine, or endocrine insufficiencies, or both, respectively. Children with SPN and benign neoplasms all survived. Overall, there were 14 (22%) recurrences and 11 deaths (17%). Univariate analysis revealed non-SPN malignant tumor diagnosis, preoperative vascular involvement, intraoperative transfusion requirement, pathologic vascular invasion, positive margins, and need for neoadjuvant chemotherapy as risk factors for recurrence and poor survival. Multivariate analysis only revealed pathologic vascular invasion as a risk factor for recurrence and poor survival.

CONCLUSION

This is the largest series of pediatric PD patients. PD is curative for SPN and benign neoplasms. Pancreatic insufficiency is the most common postoperative complication. Outcome is primarily associated with histology.

Thoracoscopy vs thoracotomy for the management of metastatic osteosarcoma: A Pediatric Surgical Oncology Research Collaborative Study

Complete surgical resection of pulmonary metastatic disease in patients with osteosarcoma is crucial to long-term survival. Open thoracotomy allows palpation of nodules not identified on imaging but the impact on survival is unknown. The objective of this study was to compare overall survival (OS) and pulmonary disease-free survival (DFS) in children who underwent thoracotomy vs thoracoscopic surgery for pulmonary metastasectomy. A multi-institutional collaborative group retrospectively reviewed 202 pediatric patients with osteosarcoma who underwent pulmonary metastasectomy by thoracotomy (n = 154) or thoracoscopy (n = 48). Results were analyzed by Kaplan-Meier survival estimates and multivariate Cox proportional hazard regression models. With median follow-up of 45 months, 135 (67.5%) patients had a pulmonary relapse and 95 (47%) patients were deceased. Kaplan-Meier analysis showed no significant difference in 5-year pulmonary DFS (25% vs 38%; P = .18) or OS (49% vs 42%, P = .37) between the surgical approaches of thoracotomy and thoracoscopy. In Cox regression analysis controlling for other factors impacting outcome, there was a significantly increased risk of mortality (HR 2.11; P = .027; 95% CI 1.09-4.09) but not pulmonary recurrence (HR 0.96; P = .90; 95% CI 0.52-1.79) with a thoracoscopic approach. However, in the subset analysis limited to patients with oligometastatic disease, thoracoscopy had no increased risk of mortality (HR 1.16; P = .62; 0.64-2.11). In conclusion, patients with metastatic osteosarcoma and limited pulmonary disease burden demonstrate comparable outcomes after thoracotomy and thoracoscopy for metastasectomy. While significant selection bias in these surgical cohorts limits the generalizability of the conclusions, clinical equipoise for a randomized clinical trial in patients with oligometastatic disease is supported.

Abstract 3905: Human liver organoids for disease modeling of fibrolamellar hepatocellular carcinoma

Fibrolamellar Hepatocellular Carcinoma (FLC) is a usually lethal liver cancer affecting adolescents and young adults without previous liver disease. FLC is characterized by a ~400kb nucleotide deletion resulting in a fusion of a heatshock protein cofactor, DNAJB1, with the catalytic subunit of protein kinase A (PRKACA). One limitation to the study of this disease is the lack of in vitro models. Organoids have shown utility as a model system for studying many diseases, including cancer. This study describes the development and characterization of FLC tumor organoids. With IRB approval, normal liver and FLC tumor tissue was obtained from patients undergoing surgical resection. Liver cells were isolated from the tissue samples and placed into a 3D basement membrane matrix and the media supplemented with growth factors specific to promote liver organoid expansion. Normal and tumor organoids were analyzed by microscopy for morphology, by PCR for presence of the DNAJB1-PRKACA chimeric transcript, by Western blot for chimeric protein expression, and by RNA sequencing for transcriptomic changes. Eight organoid lines have been developed from normal liver and eight from FLC tumor tissue, including multiple independent organoids developed from different metastases from the same patient. A distinct morphological difference between normal liver organoids and FLC tumor organoids can be seen with either brightfield microscopy or with H&E. The DNAJB1-PRKACA chimeric transcript was detected in all of the tumor tissue and tumor organoids by RT-PCR and not detected in any of the normal tissue or organoids. The presence of the DNAJB1-PRKACA fusion protein was verified by Western blot in tumor organoids and tissue but not detectable in the normal tissue. The RNA sequencing analysis shows clustering of tumor organoids with tumor tissue. Tumor organoids injected subcutaneously in mice grew as tumors. Now that the normal and tumor organoids have been developed and validated, they are being used for screening for potential therapeutics.

Citation Format: Nicole J. Croteau, David Requena, Gadi Lalazar, Denise Ng, Solomon Levin, Bassem Shebl, Ruisi Wang, William J. Hammond, James A. Saltsman, Helmuth Gehart, Hans Clevers, Michael P. LaQuaglia, Sanford Simon. Human liver organoids for disease modeling of fibrolamellar hepatocellular carcinoma [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr 3905.

A novel image-based system for risk stratification in patients with desmoplastic small round cell tumor

BACKGROUND

Desmoplastic small round cell tumor (DSRCT) is an aggressive soft tissue sarcoma affecting children and young adults with 5-year overall survival (OS) of approximately 20%. Despite generally poor prognosis, long-term survival does occur. However, no evidence-based system exists to risk-stratify patients at diagnosis.

METHODS

We retrospectively reviewed all DSRCT cases diagnosed at our institution between January 2000 and September 2016. Demographics, diagnostic imaging, and clinical data were reviewed. Univariate and multivariate Cox proportional hazard modeling was used to evaluate associations between imaging characteristics and OS.

RESULTS

There were 130 patients (85% male; median age at presentation: 21.2 years) with confirmed DSRCT and sufficient imaging and clinical information for analysis. Median 5-year OS was 28% (95% CI: 19%-37%). In univariate analysis, shorter OS was associated with presence of liver lesions (hazard ratio [HR] 2.1, 95% CI: 1.28-3.45), chest lesions (HR 1.86, 95% CI: 1.11-3.1), and ascites (HR 1.69, 95% CI: 1.06-2.7). In multivariate analysis, liver involvement and ascites were predictive and were used to stratify risk (intermediate=no liver involvement or ascites; high=either liver involvement or ascites; very high=both liver involvement and ascites). Intermediate-risk patients had a 5-year survival of 61% (95% CI: 40%-76%) versus 16% (95% CI: 6%-29%) among high-risk patients and 8% (95% CI: 1%-29%) among very high risk patients.

CONCLUSION

Patients with DSRCT can be risk-stratified at diagnosis based on specific imaging characteristics.

TYPE OF STUDY

Retrospective study with no comparison group.

LEVEL OF EVIDENCE

Level IV.

Assessment of pulmonary outcomes, exercise capacity, and longitudinal changes in lung function in pediatric survivors of high-risk neuroblastoma

BACKGROUND/OBJECTIVES

Survivors of high-risk neuroblastoma (NB) are exposed to multimodality therapies early in life and confront late therapy-related toxicities. This study assessed respiratory symptoms, exercise capacity, and longitudinal changes in pulmonary function tests (PFTs) among survivors.

DESIGN/METHODS

Survivors of high-risk NB followed in the long-term follow-up clinic at Memorial Sloan Kettering Cancer Center were enrolled. Symptom and physical activity questionnaires were completed. Medical records were reviewed for treatments and comorbidities. Participants completed spirometry, plethysmography, diffusion capacity of the lung for carbon monoxide, 6-minute walk tests (6MWTs), and cardiopulmonary exercise testing. Questionnaires and PFTs were repeated at least one year after enrollment.

RESULTS

Sixty-two survivors participated (median age at study: 10.92 years; median age at diagnosis: 2.75 years; median time since completion of therapy: 5.29 years). Thirty-two percent had chronic respiratory symptoms. Seventy-seven percent had PFT abnormalities, mostly mild to moderate severity. Thirty-three completed 6MWTs (median, 634.3 meters); eight completed cardiopulmonary exercise tests (mean VO₂ max: 63% predicted); 23 completed a second PFT revealing declines over a median 2.97 years (mean percent predicted forced vital capacity: 79.9 to 70.0; mean forced expiratory volume in 1 second: 81.6 to 69.9). Risks for abnormalities included thoracic surgery, chest radiation therapy (RT), thoracic surgery plus chest RT, and hematopoietic stem cell transplant.

CONCLUSIONS

In this cohort of survivors of high-risk NB, PFT abnormalities were common but mostly mild or moderate. Maximal exercise capacity may be affected by respiratory limitations and declines in lung function may occur over time. Continued pulmonary surveillance of this at-risk population is warranted.

Error traps and culture of safety in pediatric surgical oncology

This article reviews technical issues to improve surgical safety and avoid surgical errors in pediatric surgical oncology, particularly in the three most common extracranial solid tumors: neuroblastoma, hepatoblastoma and Wilms tumor. The use of adjuvant chemotherapy - when indicated - the use of tumor specific classifications, adequate surgical planning, that may include the use of 3D printable models, improved surgical instruments and technology, and following surgical guidelines, would result in avoiding error, increased safety, and therefore in improved surgical outcomes.

Reduced-Dose Radiation Therapy to the Primary Site is Effective for High-Risk Neuroblastoma: Results From a Prospective Trial

PURPOSE

For patients with high-risk neuroblastoma (HR-NB), a dose of 21 Gy to the primary tumor site after gross total resection (GTR) provides excellent local control. However, no clinical trial has specifically evaluated the optimal dose of radiation therapy (RT), and RT-related long-term toxicities are of increasing concern. We sought to assess local control, survival outcomes, and toxicity after a reduction in dose to the primary site from 21 Gy to 18 Gy.

METHODS AND MATERIALS

After induction chemotherapy and GTR, patients with HR-NB were enrolled and treated on an RT dose-reduction prospective trial with 18 Gy hyperfractionated RT given in twice-daily fractions of 1.5 Gy each.

RESULTS

The 25 study subjects were 1.6 to 9.5 (median, 4.3) years old at enrollment and included 23 (92%) with stage IV and II (8%) with MYCN-amplified stage III disease. Eleven (44%) were in complete remission (CR), and 14 (56%) had persistence of osteomedullary disease postinduction. Three patients (12%) received proton therapy, and the rest received intensity modulated photon therapy. After a follow-up of 1.8 to 4.2 (median, 3.5) years from initiation of RT, no failures occurred within the RT field; 3 patients had marginal recurrences. The respective 3-year progression-free and overall survival rates were 54.5% and 90.9% for patients in first CR and 42.9% and 76.2% for patients not in metastatic CR. Acute toxicity was negligible.

CONCLUSIONS

Reduced-dose RT with 18 Gy did not compromise local control or survival outcomes in our cohort of patients with HR-NB after GTR. These findings support assessing further RT dose reduction and validation on a larger, multi-institutional trial.

Maintenance chemotherapy to reduce the risk of a metachronous Wilms tumor in children with bilateral nephroblastomatosis

From 2009 to 2018, 10 consecutive patients with Wilms tumors and bilateral nephroblastomatosis, who had completed standard therapy, were provided a maintenance chemotherapy regimen consisting of vincristine and dactinomycin every 3 months for 12 months in order to prevent an early metachronous Wilms tumor. One patient (10%) with Beckwith-Wiedemann syndrome developed a new tumor, without anaplasia. There were no significant toxicities reported during maintenance. All patients are currently alive with no evidence of disease. Further investigations are recommended to determine the utility of this approach.

MYOD1-mutant spindle cell and sclerosing rhabdomyosarcoma: an aggressive subtype irrespective of age. A reappraisal for molecular classification and risk stratification

Sclerosing and spindle cell rhabdomyosarcoma is a rare histologic subtype, designated in the latest WHO classification as a stand-alone pathologic entity. Three genomic groups have been defined: an infantile subset of spindle cell rhabdomyosarcoma harboring VGLL2-related gene fusions, a MYOD1-mutant subset commonly associated with sclerosing morphology, and a subset lacking recurrent genetic abnormalities. In this study, we focus on MYOD1-mutant rhabdomyosarcoma to further define their clinicopathologic characteristics and behavior in a larger patient cohort. We investigated 30 cases of MYOD1-mutant rhabdomyosarcoma (12 previously reported and 18 newly diagnosed) with an age range of 2-94 years, including 15 children. All cases showed morphology within the spectrum of spindle cell/sclerosing rhabdomyosarcoma (8 cases showing pure sclerosing morphology, 8 cases  showing pure spindle cell morphology and 14 cases showing a hybrid phenotype of spindle, sclerosing and primitive undifferentiated areas). All tumors harbored either homozygous or heterozygous MYOD1 (p.L122R) exon 1 mutations. In 10 (33%) cases, a co-existent PIK3CA mutation was identified. Hot-spot mutations in NRAS and HRAS were each identified in a single case, respectively. Follow-up was available on 22 (73%) patients with a median duration of 28 months. Local recurrence was seen in 12 (55%) and distant recurrence in 12 (55%) cases, despite multimodality chemoradiation therapy. At last follow-up, 15 (68%) patients died of the disease, one patient was alive with disease and five had no evidence of disease. The prognosis was equally poor in pediatric and adult patients. In conclusion, MYOD1 mutation defines an aggressive rhabdomyosarcoma subset, with poor outcome and response to therapy, irrespective of age. Given that this distinct molecular subtype is characterized by an aggressive biologic behavior compared to other genetic subtypes of spindle and sclerosing rhabdomyosarcoma, the MYOD1 genotype should be used as a molecular marker in both subclassification and prognostication of rhabdomyosarcoma.

Dose-escalation is needed for gross disease in high-risk neuroblastoma

BACKGROUND

Locoregional failure is common after subtotal resection in high-risk neuroblastoma. Although a dose of 21 Gy radiation therapy (RT) is standard for treatment of high-risk neuroblastoma after gross total resection, the dose needed for local control of patients with gross residual disease at the time of RT is unknown. We sought to evaluate local control after 21-36 Gy RT in patients with high-risk neuroblastoma undergoing subtotal resection.

METHODS

All patients with high-risk neuroblastoma who received RT to their primary site from 2000 to 2016 were reviewed. Of the 331 patients who received consolidative RT to their primary site, 19 (5.7%) underwent subtotal resection and were included in our analysis. Local failure (LF) was correlated with biologic prognostic factors and dose of RT.

RESULTS

Median follow-up among surviving patients was 6.0 years. Median RT dose was 25 Gy (range, 21 Gy-36 Gy). The 5-year cumulative incidence of LF among all patients was 17.2%. LF at 5 years was 30% in those who received <30 Gy versus 0% in those who received 30-36 Gy (P = 0.12). There was a trend towards improved local control in patients with tumor size ≤10 cm at diagnosis (P = 0.12). The 5-year event-free and overall survival were 44.9% and 68.7%, respectively.

CONCLUSION

After subtotal resection, patients who received less than 30 Gy had poor local control. Doses of 30-36 Gy are likely needed for optimal control of gross residual disease at the time of consolidative RT in high-risk neuroblastoma.

Treatment and outcome of adult-onset neuroblastoma

Adult-onset neuroblastoma is rare and little is known about its biology and clinical course. There is no established therapy for adult-onset neuroblastoma. Anti-GD2 immunotherapy is now standard therapy in children with high-risk neuroblastoma; however, its use has not been reported in adults. Forty-four adults (18-71 years old) diagnosed with neuroblastoma between 1979 and 2015 were treated at Memorial Sloan Kettering Cancer Center. Five, 1, 5 and 33 patients had INSS stage 1, 2, 3 and 4 diseases, respectively. Genetic abnormalities included somatic ATRX (58%) and ALK mutations (42%) but not MYCN-amplification. In the 11 patients with locoregional disease, 10-year progression-free (PFS) and overall survival (OS) was 35.4 ± 16.1% and 61.4 ± 15.3%, respectively. Among 33 adults with stage 4 neuroblastoma, 7 (21%) achieved complete response (CR) after induction chemotherapy and/or surgery. Seven patients with primary refractory neuroblastoma (all with osteomedullary but no soft tissue disease) received anti-GD2 antibodies, mouse or humanized 3F8. Antibody-related adverse events were similar to those in children, response rate being 71.4%. In patients with stage 4 disease at diagnosis, 5-year PFS was 9.7± 5.3% and most patients who were alive with disease at 5 years died of neuroblastoma over the next 5 years, 10-year OS being only 19.0 ± 8.2%. Patients who achieved CR after induction had superior PFS and OS (p = 0.006, p = 0.031, respectively). Adult-onset neuroblastoma appeared to have different biology from pediatric or adolescent NB, and poorer outcome. Complete disease control appeared to improve long-term survival. Anti-GD2 immunotherapy was well tolerated and might be beneficial.

Urothelial neoplasms in pediatric and young adult patients: A large single-center series

PURPOSE

Bladder cancer is the sixth most common cancer in the United States, but is exceedingly rare in young patients, leading to a lack of accepted standards for diagnosis, treatment, and surveillance. We review our institutional experience with bladder urothelial neoplasms in pediatric and young adult patients summarizing presentation, treatment, and outcomes.

METHODS

Surgical pathology records at our institution were searched for cases of urothelial neoplasms among patients ≤25 years of age treated between January 1997 and September 2016. Cases submitted exclusively for pathology review were excluded. Diagnoses were confirmed based on pathologic examination using the 2004 World Health Organization classification system.

RESULTS

Thirty-four patients were identified with a mean age of 21.1 years (range 8-25 years), and median follow-up was 25.1 months (1-187 months). The male to female ratio was 1.83:1. The most common presenting symptom was hematuria (n=26; 76%). Diagnoses were invasive urothelial carcinoma (n=3), noninvasive urothelial carcinoma (n=24), PUNLMP (n=6), and urothelial papilloma (n=1). Noninvasive lesions were resected by cystoscopy, after which 12% (n=4) experienced complications (grade II or greater). One patient with stage IV invasive disease at diagnosis died, and 2 patients developed recurrences. Of those with noninvasive carcinoma, 29% (n=7) required repeat cystoscopy soon after initial TURBT at outside institutions, and 17% (n=4) had tumors downgraded from high-grade to low-grade after pathology review.

CONCLUSION

Hematuria is the most common sign of bladder neoplasia in children and young adults and should be investigated by cystoscopy. The majority of urothelial neoplasms in these patients are noninvasive and can be successfully treated with transurethral resection.

LEVEL OF EVIDENCE

Level IV (Retrospective study with no comparison group).

Radiation Therapy to Sites of Metastatic Disease as Part of Consolidation in High-Risk Neuroblastoma: Can Long-term Control Be Achieved?

PURPOSE

As part of consolidative therapy in high-risk neuroblastoma, modern protocols recommend radiation therapy (RT) both to the primary site and to sites of metastatic disease that persist after induction chemotherapy. Although there are abundant data showing excellent local control (LC) with 21 Gy directed at the primary site, there are few data describing the feasibility and efficacy of RT directed at metastatic sites of disease as part of consolidation.

METHODS AND MATERIALS

All patients with neuroblastoma who received RT to metastatic sites of disease as a part of consolidative therapy at a single institution between 2000 and 2015 were reviewed. Among 159 patients, 244 metastases were irradiated.

RESULTS

The median follow-up period among surviving patients was 7.4 years. Over 85% of the irradiated metastases were treated with 21 Gy (range, 10.5-36 Gy). Tumor recurrence occurred in 43 of 244 irradiated metastases (18%). The 5-year LC rate of treated metastatic sites was 81%. Metastatic sites that cleared with induction chemotherapy had improved LC compared with sites with persistent uptake on metaiodobenzylguanidine scans (LC rate, 92% vs 67%; P < .0001). LC at irradiated metastatic sites did not differ based on total number of sites irradiated or site of disease irradiated (bone vs soft tissue). Patients with bulky, resistant disease who were treated with 30 to 36 Gy had worse LC (P = .02). However, on multivariate analysis, only persistence after induction chemotherapy remained a significant prognostic factor for LC (hazard ratio, 3.7; P < .0001). Patients who had LC at irradiated metastatic sites had improved overall survival compared with those who did not (overall survival rate, 71% vs 50%; P < .0001).

CONCLUSIONS

Response to chemotherapy is an important prognostic factor for LC at irradiated metastatic sites in neuroblastoma. Overall, consolidative RT appears to be an effective modality of LC. Long-term disease control can be achieved with such an approach.

Unusual abdominal metastases in osteosarcoma

Intraabdominal metastases in the setting of osteosarcoma are very rare. We describe a case of a 17-year-old boy with high-grade right distal femur osteosarcoma who two years after diagnosis developed extensive intra abdominal metastases involving the omentum, peritoneum, bowel serosa, psoas muscles and abdominal soft tissue. Awareness of and surveillance for unusual patterns of metastasis may allow for earlier detection, intervention, and palliative care decision-making, which may affect survival and quality of life. This report underlines the need for prospective studies evaluating surveillance guidelines for patients after medical and surgical management of osteosarcoma, especially in cases complicated by pulmonary metastases.

MYCN-amplified stage 2/3 neuroblastoma: excellent survival in the era of anti-GD2 immunotherapy

High-risk neuroblastoma (HR-NB) includes MYCN-amplified stage 2/3, but reports covering anti-G_D2 immunotherapy, which recently became standard for HR-NB, do not provide details on this subset. We now report on all 20 MYCN-amplified stage 2/3 patients who received induction chemotherapy at our center during the era of consolidation with anti-G_D2 antibody 3F8/ granulocyte-macrophage colony-stimulating factor (GM-CSF) (2000-2015). Early in this period, consolidation included autologous stem-cell transplantation (ASCT). Event-free survival (EFS) and overall survival (OS) were estimated using Kaplan-Meier analyses. With induction, 19/20 (95%) patients achieved complete/very good partial remission (CR/VGPR) but one had progressive disease with early death. One responder did not receive consolidation and died of relapse. Five-year post-diagnosis EFS/OS rates for all 20 patients were 72%/84%. The 18 CR/VGPR patients who received consolidation had EFS/OS 81%/94% at five years from starting 3F8/GM-CSF: 4/4 ASCT patients remained relapse-free, while 11/14 non-ASCT patients remained relapse-free and two of the three relapsed patients achieved 2^nd CR (consolidated by retreatment with 3F8/GM-CSF) and remained in 2^nd CR at 36+ and 95+ months post-relapse. The 14 non-ASCT patients had EFS/OS 73.5%/93% at five years from starting 3F8/GM-CSF. This subset appears to have a good prognosis with contemporary multi-modality therapy, possibly even without ASCT.

Molecular Subtypes of KIT/PDGFRA Wild-Type Gastrointestinal Stromal Tumors: A Report From the National Institutes of Health Gastrointestinal Stromal Tumor Clinic

IMPORTANCE

Wild-type (WT) gastrointestinal stromal tumors (GISTs), which lack KIT and PDGFRA gene mutations, are the primary form of GIST in children and occasionally occur in adults. They respond poorly to standard targeted therapy. Better molecular and clinical characterization could improve management.

OBJECTIVE

To evaluate the clinical and tumor genomic features of WT GIST.

DESIGN, SETTING, AND PARTICIPANTS

Patients enrolled in an observational study at the National Institutes of Health starting in 2008 and were evaluated in a GIST clinic held once or twice yearly. Patients provided access to existing medical records and tumor specimens. Self-referred or physician-referred patients younger than 19 years with GIST or 19 years or older with known WT GIST (no mutations in KIT or PDGFRA) were recruited; 116 patients with WT GIST were enrolled, and 95 had adequate tumor specimen available. Tumors were characterized by immunohistochemical analysis (IHC) for succinate dehydrogenase (SDH) subunit B, sequencing of SDH genes, and determination of SDHC promoter methylation. Testing of germline SDH genes was offered to consenting patients and families.

MAIN OUTCOMES AND MEASURES

For classification, tumors were characterized by SDHA, B, C, or D (SDHX) mutations and other genetic and epigenetic alterations, including presence of mutations in germline. Clinical characteristics were categorized.

RESULTS

Wild-type GIST specimens from 95 patients (median age, 23 [range, 7-78] years; 70% female) were classified into 3 molecular subtypes: SDH-competent (n = 11), defined by detection of SDHB by IHC; and 2 types of SDH-deficient GIST (n = 84). Of SDH-deficient tumors, 63 (67%) had SDH mutations, and in 31 of 38 (82%), the SDHX mutation was also present in germline. Twenty-one (22%) SDH-deficient tumors had methylation of the SDHC promoter leading to silencing of expression. Mutations in known cancer-associated pathways were identified in 9 of 11 SDH-competent tumors. Among patients with SDH-mutant tumors, 62% were female (39 of 63), median (range) age was 23 (7-58) years, and approximately 30% presented with metastases (liver [12 of 58], peritoneal [6 of 58], lymph node [15 of 23]). SDHC-epimutant tumors mostly affected young females (20 of 21; median [range] age, 15 [8-50] years), and approximately 40% presented with metastases (liver [7 of 19], peritoneal [1 of 19], lymph node [3 of 8]). SDH-deficient tumors occurred only in the stomach and had an indolent course.

CONCLUSIONS AND RELEVANCE

An observational study of WT GIST permitted the evaluation of a large number of patients with this rare disease. Three molecular subtypes with implications for prognosis and clinical management were identified.

Anti-GD2 immunotherapy in adults with high-risk neuroblastoma (HR-NB): The Memorial Sloan Kettering Cancer Center (MSKCC) experience

10550

Background: The diagnosis of NB in adulthood is rare and little is known about its biology and clinical course. There is no established therapy for adult NB. Anti-GD2 immunotherapy is now standard in children with HR-NB but its use has not been reported in adults. Methods: After obtaining IRB waiver, records of all patients with adult-onset (≥18 years) NB seen at MSKCC between 1983 and 2015 were reviewed. Overall survival (OS) was tested by log-rank test. Cox-regression was used for multivariate analysis. Results: The subjects were 42 adults (median: 25; range18-71 years); 23 male and 19 female. Five, 1, 1 and 35 patients had INSS stage 1, 2, 3 and 4 disease, respectively. Genetic abnormalities included somatic ATRX (59%) and ALK mutations (43%) but not MYCN-amplification. 16 patients remain alive at a median follow-up of 5.3 years. OS for non-stage 4 patients was superior to stage 4 (median survival 14.6 vs 5.3 years; p < 0.05). However 5/7 patients with < stage 4 NB progressed to stage 4. Among 35 stage 4 patients, 4 achieved complete remission (CR) after induction chemotherapy and surgery, 11 underwent autologous stem cell transplant (ASCT) and 15 received multiple cycles of anti-GD2 antibodies 3F8 or hu3F8 without complications. In univariate analysis, patients ≤ 29 years old (n = 24) at diagnosis, those achieving CR, and those receiving anti-GD2 antibodies had superior OS (p < 0.05 for each). ASCT was not beneficial (p = 0.3 for ASCT vs no ASCT). For stage 4 patients, anti-GD2 immunotherapy was associated with favorable OS in multivariate analysis (95% CI of anti-GD2 antibody: 1.270 to 7.990). Conclusions: Adult-onset stage 4 NB demonstrates a high incidence of somatic mutations and is only partially chemosensitive. However, 3F8/hu3F8-based anti-GD2 immunotherapy appears to improve long-term survival and is well tolerated.

Acute myeloid leukemia therapy elicits durable complete response in chemoradio-resistant metastatic paraganglioma

Few effective therapeutic options exist for patients with metastatic paraganglioma (PGL). We report the case of a 16-year-old male who developed acute myeloid leukemia (AML) 30 months following the treatment for metastatic PGL. PGL had been refractory to ¹³¹ I-meta-iodobenzylguanidine and temozolomide therapy. However, there was a major reduction in primary tumor allowing its gross total resection, and complete resolution of metastatic disease following AML-directed therapy that included daunorubicin, cytarabine, and etoposide. He remains in remission for both AML and PGL, 48 months post AML chemotherapy. Alternative chemotherapeutic agents should be considered for metastatic PGL resistant to conventional therapy.

Renal Function Outcomes of High-risk Neuroblastoma Patients Undergoing Radiation Therapy

PURPOSE

To analyze the renal function outcomes in patients undergoing radiation therapy for neuroblastoma.

METHODS AND MATERIALS

The clinical metrics of renal function were analyzed in patients undergoing radiation therapy for high-risk neuroblastoma from 2000 to 2015. The blood urea nitrogen (BUN) and creatinine values before radiation therapy were compared with last available follow-up values and analyzed with the clinical circumstances, including follow-up length, age at primary irradiation, nephrectomy, and radiation technique. The creatinine clearance was estimated using the Shull method.

RESULTS

With a median follow-up period of 3.5 years, none of the 266 patients studied developed a chronic renal insufficiency. For all patients, the creatinine level increased from 0.44 to 0.51 mg/dL and the BUN increased from 10.53 to 15.52 mg/dL. Three patients required antihypertensive medication. The patients who underwent intensity modulated radiation therapy did not experience increased creatinine levels during the follow-up period; however, they had a reduced median follow-up length compared with patients treated with anteroposterior/posteroanterior beams (4.7 vs 3.3 years). A longer follow-up length was associated with an increased creatinine level. The preradiation therapy creatinine level increased with patient age, similar to that of the last follow-up creatinine level, suggesting that the changes in creatinine could likely be explained by physiologic increases associated with aging rather than radiation-induced renal damage. The creatinine clearance did not decrease in any circumstance.

CONCLUSIONS

The present cohort had excellent renal outcomes after radiation therapy for neuroblastoma. No patient developed chronic renal insufficiency, and the small increases in BUN and creatinine we observed correlated, as expected, with increases in patient age. The results of the present study revealed a possible advantage for intensity modulated radiation therapy in preserving renal function; however, the follow-up length is a recognized confounding variable. The kidneys are vital structures to consider when planning radiation therapy for neuroblastoma patients, and we have found encouraging evidence that modern techniques to spare them in the setting of multiple treatment-related insults have been successful.

Pancreaticoduodenectomy for pediatric and adolescent pancreatic malignancy: A single-center retrospective analysis

PURPOSE

While pancreaticoduodenectomy (PD) has been extensively studied in adults, there are few data pertaining specifically to pediatric patients. We retrospectively analyzed PD-associated morbidity and mortality in pediatric patients.

METHODS

Our analytic cohort included all consecutive patients ≤18years of age treated at our institution from 1993 to 2015 who underwent PD. Patient data (demographics, disease characteristics, surgical and adjuvant treatment, length of hospital stay, and postoperative course) were extracted from the medical records.

RESULTS

We identified 12 children with a median age of 9years (7 female, 5 male). Final diagnoses were pancreatoblastoma (n=3), solid pseudopapillary tumor (n=3), neuroblastoma (n=2), rhabdomyosarcoma (n=2), and neuroendocrine carcinoma (n=2). Four patients underwent PD for resection of recurrent disease. 75% (9/12 patients) received neoadjuvant therapy. The median operative time was approximately 7hours with a mean blood loss of 590cm³. The distal pancreas was invaginated into the posterior stomach (n=3) or into the jejunum (n=5) or was directly sewn to the jejunal mucosa (n=4). There were no operative deaths. There were 4 patients (34%) with grade II complications, 1 with a grade IIIb complication (chest tube), and 1 with a grade IV complication (reexploration). The most common long-term morbidity was pancreas exocrine supplementation (n=10; 83%). Five patients (42%) diagnosed with either solid pseudopapillary tumor or rhabdomyosarcoma are currently alive with a mean survival of 77.4months.

CONCLUSION

Pancreaticoduodenectomy is a feasible management strategy for pediatric pancreatic malignancies and is associated with acceptable morbidity and overall survival. Long-term outcome is mostly dependent on histology of the tumor.

LEVEL OF EVIDENCE

Level IV; retrospective study with no comparison group.

A 20-year retrospective analysis of CT-based pre-operative identification of pulmonary metastases in patients with osteosarcoma: A single-center review

PURPOSE

Cooperative studies support complete metastasectomy in osteosarcoma (OS). Pre-operative CT is used to identify and quantify metastases and can facilitate minimally invasive techniques. Here we assess the accuracy of pre-operative CT compared to findings at thoracotomy and its change over time.

METHODS

We reviewed OS thoracotomies performed at our institution from 1996 to 2015. The number of metastases identified on pre-operative chest CT was compared to the number of metastases seen on pathology (both metastases with viable cells and non-viable, osteoid-only metastases).

RESULTS

Eighty-eight patients underwent 161 thoracotomies with a median of 14days (range, 1-85) between CT and surgery, a median of 2 CT-identified lesions (range, 0-15), and a median of 4 resected lesions (range, 1-25). In 56 (34.8%) cases, more metastases were found surgically than were seen on CT, and among these, 34 (21.1%) had a greater number of viable metastases. There was poor overall correlation between CT and pathology findings (Kendall Tau-b=0.506), regardless of CT slice thickness, decade of thoracotomy, or total number of CT-identified lesions.

CONCLUSIONS

CT accuracy in pre-operatively quantifying OS pulmonary metastases has not improved in recent decades. Consequently, we recommend an open technique with direct lung palpation for complete identification and resection of OS pulmonary metastases.

LEVEL OF EVIDENCE

Level IV, retrospective study with no comparison group.

Management of desmoplastic small round cell tumor

Desmoplastic small round cell tumor (DSRCT) is a soft tissue sarcoma of mesenchymal cell origin that typically presents with multiple intra-abdominal tumors and exhibits a multi-phenotypic pattern of immunohistochemical staining. The specific organ or tissue type of origin has yet to be identified. DSRCT rarely arises as a singular tumor in the abdomen; in most cases, there are dozens to hundreds of abdominal peritoneal tumors that are detected on diagnosis. One very large dominant mass is usually present in the omentum, with an additional one or two large conglomerates of tumors in the pelvis and right peritoneum, respectively. Despite an often overwhelmingly large number of abdominal tumors, symptoms of bowel obstruction are rare. Ascites may be present. In late stages, pleural effusions, pleural implants, mediastinal adenopathy, supraclavicular adenopathy, or bone metastasis may be present. With this challenging disease, multidisciplinary therapy, including aggressive surgery, is warranted. This review will address DSRCT biology and treatment options and discuss outcomes.

Image-defined risk factors for nephrectomy in patients undergoing neuroblastoma resection

BACKGROUND

Although nephrectomy rates are higher in children with neuroblastoma who have image-defined risk factors and/or high-risk disease who undergo resection prior to chemotherapy, no published data outline the key radiographic and clinical characteristics associated with nephrectomy.

METHODS

With IRB approval, imaging studies of children undergoing primary resection of intraabdominal neuroblastoma between 2000 and 2014 were retrospectively reviewed. Fisher's exact and Wilcoxon rank-sum tests were used to compare categorical and continuous variables, respectively, with p-values adjusted for multiple testing using the false discovery rate approach.

RESULTS

Twenty-seven of 380 consecutive patients with CT imaging obtained prior to primary neuroblastoma resection underwent partial or total nephrectomy. On preoperative imaging, renal vessel narrowing and encasement and tumor invasion of the renal hilum, pelvis, and/or parenchyma were present significantly more frequently among patients undergoing nephrectomy. Delayed renal excretion of contrast, hydronephrosis, and tumors with MYCN amplification were also more prevalent in the nephrectomy group.

CONCLUSION

Encasement and narrowing of renal vessels, delayed excretion, and tumor invasion into the kidney, particularly pelvis and capsule invasion, are significantly associated with partial or total nephrectomy at initial neuroblastoma resection. These observations provide valuable information for surgical planning as well as presurgical discussions with families prior to neuroblastoma resection.

Local Control With 21-Gy Radiation Therapy for High-Risk Neuroblastoma

PURPOSE

To evaluate local control after 21-Gy radiation therapy (RT) to the primary site in patients with high-risk neuroblastoma.

METHODS AND MATERIALS

After receiving dose-intensive chemotherapy and gross total resection (GTR), 246 patients (aged 1.2-17.9 years, median 4.0 years) with high-risk neuroblastoma underwent RT to the primary site at Memorial Sloan Kettering from 2000 to 2014. Radiation therapy consisted of 21 Gy in twice-daily fractions of 1.5 Gy each. Local failure (LF) was correlated with biologic prognostic factors and clinical findings at the time of diagnosis and start of RT.

RESULTS

Median follow-up of surviving patients was 6.4 years. Cumulative incidence of LF was 7.1% at 2 years after RT and 9.8% at 5 years after RT. The isolated LF rate was 3.0%. Eighty-six percent of all local failures were within the RT field. Local control was worse in patients who required more than 1 surgical resection to achieve GTR (22.4% vs 8.3%, P=.01). There was also a trend toward inferior local control with MYCN-amplified tumors or serum lactate dehydrogenase ≥1500 U/L (P=.09 and P=.06, respectively).

CONCLUSION

After intensive chemotherapy and maximal surgical debulking, hyperfractionated RT with 21 Gy in high-risk neuroblastoma results in excellent local control. Given the young patient age, concern for late effects, and local control >90%, dose reduction may be appropriate for patients without MYCN amplification who achieve GTR.

Salvage rates after progression of high-risk neuroblastoma with a soft tissue mass

PURPOSE

Treatment of progression in high-risk neuroblastoma remains challenging despite improved survival. We retrospectively evaluated outcomes in children with a first progression that included soft-tissue masses.

METHODS

We reviewed records of 903 consecutive children with high-risk neuroblastoma diagnosed between 2004 and 2014, and identified 42 whose first progression included soft-tissue masses. Data on demographics, disease characteristics, treatment, and survival were collected. Primary outcome was 5-year overall survival (OS) from time of first progression. Secondary outcomes were local disease-free progression (LDFR) and progression-free survival (PFS) postprogression. We evaluated the prognostic significance of concomitant bone/bone marrow involvement, MYCN status, and multifocality of soft tissue relapse.

RESULTS

Median age at diagnosis was 3.0 (range: 1-10.7) years. Median time to first relapse or progression was 1.2 (range: 0.1-4.5) years after complete remission or minimal stable residual disease. Twelve (29%) patients had concomitant bone or marrow involvement at progression/relapse. There were 11 (26%) patients with International Neuroblastoma Staging System stage 3 disease (all with MYCN amplification), and 31 (74%) with stage 4 disease (12 with MYCN amplification). Nine (21%) patients had multifocal soft tissue progression. R1 resection was achieved in 41 children (95%), 38 (95%) of whom also received salvage radiation therapy. Five-year OS postprogression was 35% (95% CI: 19-51%), 5-year LDFS was 52% (95% CI: 32-72%), and 5-year PFS postprogression was 20% (95% CI: 6-34%).

CONCLUSION

Among children with high-risk neuroblastoma who underwent aggressive treatment of a first soft-tissue recurrence, 5-year postprogression overall survival was 34%. Multifocality and MYCN amplification were the predominant prognostic correlates for worse survival.

The genomic landscape of fibrolamellar hepatocellular carcinoma: whole genome sequencing of ten patients

Fibrolamellar hepatocellular carcinoma is a rare, malignant liver tumor that often arises in the otherwise normal liver of adolescents and young adults. Previous studies have focused on biomarkers and comparisons to traditional hepatocellular carcinoma, and have yielded little data on the underlying pathophysiology. We performed whole genome sequencing on paired tumor and normal samples from 10 patients to identify recurrent mutations and structural variations that could predispose to oncogenesis. There are relatively few coding, somatic mutations in this cancer, putting it on the low end of the mutational spectrum. Aside from a previously described heterozygous deletion on chromosome 19 that encodes for a functional, chimeric protein, there were no other recurrent structural variations that contribute to the tumor genotype. The lack of a second-hit mutation in the genomic landscape of fibrolamellar hepatocellular carcinoma makes the DNAJB1-PRKACA fusion protein the best target for diagnostic and therapeutic advancements. The mutations, altered pathways and structural variants that characterized fibrolamellar hepatocellular carcinoma were distinct from those in hepatocellular carcinoma, further defining it as a distinct carcinoma.