David M. Loeb

Epithelioid sarcoma: one institution’s experience with a rare sarcoma

BACKGROUNDnEpithelioid sarcomas (ES) are extremely rare soft tissue sarcomas. As such, their clinical behavior and response to treatment are poorly described in the literature.nnnMETHODSnWe queried the centralized cancer registry and pathology archives at the Johns Hopkins Medical Institution and identified 22 patients with a diagnosis of ES. We excluded two patients because of inadequate data. A pathologist reviewed patient charts and reexamined available histological slides. This study was performed with institutional review board approval.nnnRESULTSnThe median age at diagnosis was 27.8 y; most patients (75%) were male. Regional lymph node metastases were present in 10% of patients at presentation. The majority of tumors (57.9%) recurred and 35% recurred more than once, although the number of recurrences did not affect survival (P = 0.48). Patients did not experience a decrease in time to recurrence with increasing number of resections. The median time between resection and recurrence was 1.23 y and the maximum was 18.8 y. Median overall survival was 56.2 mo and 5-y survival was 92%.nnnCONCLUSIONSnOur study reveals that ES is an extremely rare tumor with a protracted and recurrent course, but overall survival may be more favorable than in the past. Patients benefit from aggressive and repeated resection. Epithelioid sarcoma is unique because it metastasizes to regional nodal basins. Extended surveillance is indicated, because recurrences can appear after decades of quiescence.

Single-Agent Post-Transplantation Cyclophosphamide as Graft-versus-Host Disease Prophylaxis after Human Leukocyte Antigen–Matched Related Bone Marrow Transplantation for Pediatric and Young Adult Patients with Hematologic Malignancies

High-dose cyclophosphamide given after HLA-matched related and unrelated allogeneic bone marrow transplantation (BMT) for patients with hematologic malignancies is effective single-agent graft-versus-host disease (GVHD) prophylaxis in adults. Data describing outcomes for pediatric and young adult patients have not been reported. Between the years 2007 and 2013, 29 pediatric and young adult patients ages ≤21xa0years of age treated at our institution for high-risk hematologic malignancies underwent myeloablative HLA-matched related Txa0cell-replete BMT. Eleven patients received post-transplantation cyclophosphamide (PTCy) as single-agent GVHD prophylaxis and were followed prospectively. Eighteen patients received calcineurin inhibitor (CNI)-based standard GVHD prophylaxis and were studied retrospectively as a control group. No acute GVHD (aGVHD) developed in patients receiving PTCy, whereas patients receiving CNI-based GVHD prophylaxis had cumulative incidences of grades II to IV and grades III and IV aGVHD of 27% and 5%, respectively. No patients receiving PTCy developed chronic GHVD, compared to 1 in the control group. Two-year overall survival was similar between the 2 groups (54% PTCy versus 58% CNI-based prophylaxis), as was event-free survival (42% PTCy versus 47% CNI-based). The 5-year cumulative incidence of relapse was 58% for PTCy and 42% for CNI-based GVHD prophylaxis (Pxa0= .45). These results suggest that PTCy is a safe and efficacious method of GVHD prophylaxis after an HLA-matched related BMT in the pediatric and young adult population that affords patients to be off all post-transplantation immunosuppression on dayxa0+5.

Automated Functional Imaging by 2D Speckle Tracking Echocardiography Reveals High Incidence of Abnormal Longitudinal Strain in a Cohort of Pediatric Oncology Patients.

Automated functional imaging (AFI) was introduced to two‐dimensional speckle‐tracking echocardiography to facilitate strain assessment in the clinical settings. In patients treated with cardiotoxic anthracyclines, AFI may be helpful in the detection of early myocardial injury when left ventricular ejection fraction (LVEF) remains normal.

Desmoplastic small round cell tumor: postoperative retroperitoneal mass

We describe the case of a 14-year-old boy who presented with a large, 17.6-cm retroperitoneal mass, along with multiple metastases, and was diagnosed with desmoplastic small round cell tumor. After initial chemotherapy, he underwent gross total resection with a positive margin. On postoperative radiation planning computed tomography, a 6.8-cm heterogeneous mass was noted in the surgical bed. Given the tumors aggressive nature and positive surgical margins, there was real concern for recurrent disease. Further evaluation with magnetic resonance imaging elucidated that the mass consisted of simple fluid and fat, without contrast enhancement, suggesting a postoperative fluid collection. He was able to continue with adjuvant treatment as planned. This case example illustrates that even large postoperative heterogeneous masses may still be related to postoperative fluid collection in patients with aggressive tumor. However, it is important to rule out recurrent disease before starting adjuvant therapy given improved outcomes with gross total resection in desmoplastic small round cell tumor.

Abstract 3231: An orthotopic xenograft model of sarcoma metastasis demonstrates essential role of tumor microenvironment for metastasis

Sarcoma metastasis is a multi-step process that includes migration, intravasation into the circulation, extravasation and invasion to distant tissue, and distant tumor growth, and because commonly used xenograft models do not account for every step in the process, we sought to develop a novel metastasis model system. Our technique involves implanting small fragments of patient-derived xenografts into either the tibia or gastrocnemius muscle of NOD/SCID/IL-2Rγ knock-out mice and amputating the affected limb when the tumor reaches at least 1 cm in diameter. Mice are then followed for the development of distant metastases. We found that Ewing sarcoma, osteosarcoma, and rhabdomyosarcoma xenografts all undergo distant metastasis when implanted in an orthotopic location, but do not metastasize after subcutaneous implantation, even when the subcutaneous tumor is excised and mice are observed long-term post-excision. We also investigated whether the difference in metastatic potential is related to cell intrinsic or cell extrinsic factors. Analysis by immunofluorescence revealed that tumors are infiltrated by macrophages regardless of site of implantation, but that the polarization of these macrophages differs. We also found differences in expression of arginase and NOS2 based on site of xenograft implantation. Thus, we have demonstrated that sarcoma patient-derived xenografts undergo spontaneous distant metastasis when implanted in an orthotopic location, but not when implanted in a heterotopic location, highlighting the essential role of the tumor microenvironment in determining metastatic potential. This model has significant benefits compared with the more commonly used tail vein injection model of metastasis, which bypasses the requirements for local invasion and vascular intravasation, processes that are amenable to study using our model. We have begun to use this model to investigate the mechanisms by which tumor microenvironment influences metastasis, and also are using this model for preclinical drug evaluation to determine a therapy9s effect not only on growth of the primary tumor, but also on development of metastasis. Citation Format: Seth D. Goldstein, Masanori Hayashi, Catherine M. Albert, Kyle W. Jackson, David M. Loeb. An orthotopic xenograft model of sarcoma metastasis demonstrates essential role of tumor microenvironment for metastasis. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 3231. doi:10.1158/1538-7445.AM2015-3231

Abstract 2981: Hypoxia-sensitive dynamic methylation of a CpG island in Intron 1 of the WT1 gene regulates expression of a long noncoding RNA that controls WT1 expression in myeloid leukemia cells.

The WT1 gene encodes a zinc finger transcription factor that plays a role in both transcriptional and post-transcriptional regulation of mRNA expression. WT1 is overexpressed in a variety of solid tumors, as well as in both acute and chronic myeloid leukemias. The expression of WT1 is under tight control in the developing kidney as well as in hematopoietic stem/progenitor cells. WT1 expression is also regulated by hypoxia. A detailed understanding of the mechanisms regulating WT1 expression is, however, lacking. There is a CpG island located in Intron 1 of the WT1 gene, and we investigated whether WT1 expression might therefore be epigenetically regulated. We found that WT1 expression in myeloid leukemia cell lines correlates with hypomethylation of the Intron 1 CpG island which leads to expression of an antisense long noncoding RNA (lncRNA) transcribed from a promoter within Intron 1. Leukemia cell lines that express WT1 also demonstrate a Histone H3 methylation pattern associated with transcriptionally active chromatin, while lines that do not express WT1 have a pattern associated with transcriptionally inactive chromatin. Making WT1-negative cell lines hypoxic leads to demethylation of the Intron 1 CpG island, a change in histone methylation from predominantly H3K9 methylation to predominantly H3K4 methylation, expression of the antisense lncRNA, and expression of WT1. Prevention of HIF1 induction using shRNA blocks CpG demethylation, the changes in Histone H3 methylation, expression of the antisense lncRNA, and WT1 expression. An shRNA that blocks expression of the lncRNA in WT1-positive cell lines and blocks induction of the antisense lncRNA also blocks WT1 expression, demonstrating that the lncRNA is necessary for WT1 expression. Finally, in primary acute myeloid leukemia samples, WT1 expression correlates directly with hypomethylation of the Intron 1 CpG island, and hypoxia causes demethylation of the CpG island as well as induction of WT1 expression. We conclude that WT1 expression is regulated by an antisense lncRNA transcribed from a promoter in Intron 1, and that this promoter is regulated by methylation of the CpG island in this intron. Furthermore, hypoxia leads to demethylation of this CpG island, allowing transcription of the lncRNA, which results in the expression of WT1. We propose a novel mechanism of hypoxia-mediated regulation of gene expression: stabilization of HIF1 leads to demethylation of a specific CpG island and a change in histone methylation of the surrounding region, allowing expression of an antisense lncRNA that is necessary for upregulation of WT1 mRNA expression. Future work will investigate whether this novel mechanism of hypoxia-mediated regulation of gene expression affects other genes as well as the specific mechanism by which the antisense lncRNA controls WT1 expression. Citation Format: David M. Loeb, Gregory McCarty. Hypoxia-sensitive dynamic methylation of a CpG island in Intron 1 of the WT1 gene regulates expression of a long noncoding RNA that controls WT1 expression in myeloid leukemia cells. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 2981. doi:10.1158/1538-7445.AM2013-2981