Lineage of origin in rhabdomyosarcoma informs pharmacological response.

Lineage or cell of origin of cancers is often unknown and thus is not a consideration in therapeutic approaches. Alveolar rhabdomyosarcoma (aRMS) is an aggressive childhood cancer for which the cell of origin remains debated. We used conditional genetic mouse models of aRMS to activate the pathognomonic Pax3:Foxo1 fusion oncogene and inactivate p53 in several stages of prenatal and postnatal muscle development. We reveal that lineage of origin significantly influences tumor histomorphology and sensitivity to targeted therapeutics. Furthermore, we uncovered differential transcriptional regulation of the Pax3:Foxo1 locus by tumor lineage of origin, which led us to identify the histone deacetylase inhibitor entinostat as a pharmacological agent for the potential conversion of Pax3:Foxo1-positive aRMS to a state akin to fusion-negative RMS through direct transcriptional suppression of Pax3:Foxo1.

Probabilistic modeling of personalized drug combinations from integrated chemical screen and molecular data in sarcoma.

BACKGROUND: Cancer patients with advanced disease routinely exhaust available clinical regimens and lack actionable genomic medicine results, leaving a large patient population without effective treatments options when their disease inevitably progresses. To address the unmet clinical need for evidence-based therapy assignment when standard clinical approaches have failed, we have developed a probabilistic computational modeling approach which integrates molecular sequencing data with functional assay data to develop patient-specific combination cancer treatments. METHODS: Tissue taken from a murine model of alveolar rhabdomyosarcoma was used to perform single agent drug screening and DNA/RNA sequencing experiments; results integrated via our computational modeling approach identified a synergistic personalized two-drug combination. Cells derived from the primary murine tumor were allografted into mouse models and used to validate the personalized two-drug combination. Computational modeling of single agent drug screening and RNA sequencing of multiple heterogenous sites from a single patient's epithelioid sarcoma identified a personalized two-drug combination effective across all tumor regions. The heterogeneity-consensus combination was validated in a xenograft model derived from the patient's primary tumor. Cell cultures derived from human and canine undifferentiated pleomorphic sarcoma were assayed by drug screen; computational modeling identified a resistance-abrogating two-drug combination common to both cell cultures. This combination was validated in vitro via a cell regrowth assay. RESULTS: Our computational modeling approach addresses three major challenges in personalized cancer therapy: synergistic drug combination predictions (validated in vitro and in vivo in a genetically engineered murine cancer model), identification of unifying therapeutic targets to overcome intra-tumor heterogeneity (validated in vivo in a human cancer xenograft), and mitigation of cancer cell resistance and rewiring mechanisms (validated in vitro in a human and canine cancer model). CONCLUSIONS: These proof-of-concept studies support the use of an integrative functional approach to personalized combination therapy prediction for the population of high-risk cancer patients lacking viable clinical options and without actionable DNA sequencing-based therapy.

Epirubicin and Ifosfamide with Preoperative Radiation for High-Risk Soft Tissue Sarcomas.

BACKGROUND: The optimal treatment of high-risk soft tissue sarcomas (STS) of the extremities remains controversial. We report follow-up from a phase II study of dose-intense chemotherapy with preoperative hypofractionated radiation in this population supplemented with subsequent data from an extensive institutional experience using this regimen. METHODS: Patients with localized, intermediate- or high-grade STS of the extremity or body wall measuring > 5 cm were treated with epirubicin 30 mg/m2/day and ifosfamide 2.5 g/m2/day on days 1-4 every 21 days for 3 preoperative and 3 postoperative cycles. During cycle 2 of preoperative therapy, epirubicin was omitted, and a total of 28 Gy of radiation (8 fractions) was delivered. Twenty-five patients were treated on the phase II study (2002-2005). Fifty-one additional patients were identified from a retrospective chart review (2005-2014). RESULTS: The 5-year rates for overall survival, distant disease-free survival, and freedom from local regional failure were 70.4% (95% CI 59.2-83.7%), 55.9% (95% CI 44.5-70.2%), and 87.2% (95% CI 77.9-96.5%) respectively. Thirty-eight percent of tumors (29/76) demonstrated ≥ 90% pathologic response. Wound complications occurred in 32% (24/76) of patients. DISCUSSION: Treatment with preoperative radiation and pre- and post-operative epirubicin and ifosfamide was associated with favorable clinical outcomes. Survival and recurrence rates were comparable to those reported with other preoperative chemotherapy regimens in high-risk extremity sarcomas. Use of trimodality therapy should be considered for appropriate high-risk STS patients.

PDGFRß reverses EphB4 signaling in alveolar rhabdomyosarcoma.

Alveolar rhabdomyosarcoma (aRMS) is an aggressive myogenic childhood malignancy, not infrequently presenting as incurable metastatic disease. To identify therapeutic targets, we performed an unbiased tyrosine kinome RNA interference screen in primary cell cultures from a genetically engineered, conditional mouse model of aRMS. We identified ephrin receptor B4 (EphB4) as a target that is widely expressed in human aRMS and that portends a poor clinical outcome in an expression level-dependent manner. We also uncovered cross-talk of this ephrin receptor with another receptor tyrosine kinase, PDGFRß, which facilitates PDGF ligand-dependent, ephrin ligand-independent activation of EphB4 converging on the Akt and Erk1/2 pathways. Conversely, EphB4 activation by its cognate ligand, EphrinB2, did not stimulate PDGFRß; instead, apoptosis was paradoxically induced. Finally, we showed that small-molecule inhibition of both PDGFRß and EphB4 by dasatinib resulted in a significant decrease in tumor cell viability in vitro, as well as decreased tumor growth rate and significantly prolonged survival in vivo. To our knowledge, these results are the first to identify EphB4 and its cross-talk with PDGFRß as unexpected vital determinants of tumor cell survival in aRMS, with EphB4 at the crux of a bivalent signaling node that is either mitogenic or proapoptotic.

Proptosis Caused by Rhabdomyomatous Mesenchymal Hamartomata Occurring in the Orbit.

Two infants were referred for progressive orbital proptosis. MRI in both cases demonstrated a homogenous mass in the orbit adherent to and isointense with a rectus muscle. Histopathology in both cases demonstrated a bland proliferation of spindle cells with entrapped skeletal muscle. Immunochemistry demonstrated that the abnormal tissue was of skeletal muscle origin, consistent with rhabdomyomatous mesenchymal hamartoma (RMH). Observation was elected due to the reported benign nature of RMH. In contrast to RMH of the cutaneous tissues that typically follows a benign course, RMH of the orbit may present with rapid growth.

Inflammatory myofibroblastic tumor of the orbit: a case report.

Inflammatory myofibroblastic tumor (IMT) is a neoplasm most commonly found in the abdominal-pelvic region, lung, and retroperitoneum. The tumor tends to affect soft tissues of children and young adults and can locally recur but rarely metastasizes. Histologically, the appearance is one of bland spindle cell proliferation with a prominent, chronic inflammatory infiltrate. This article describes 1 case of IMT found in the orbit that is presented with rapidly progressive painless proptosis. In the authors' review of the literature, they have only found 2 other case reports involving the orbit.

A case study of personalized therapy for osteosarcoma.

BACKGROUND: Effective targeted therapies are needed in sarcomas, but the biological heterogeneity of these tumors has presented a challenge to clinical integration of small molecule inhibitors in sarcoma treatment. Here we outline a process to personalize therapy for sarcomas through a case study of a canine with spontaneous osteosarcoma. PROCEDURE: Rapid establishment of a primary tumor cell culture is described, followed by efficient functional characterization of the tumor that identified the Src inhibitor dasatinib as the most effective targeted therapy for this individual dog. RESULTS: Adjuvant dasatinib was administered for a total of 26 weeks following treatment with chemotherapy. Pharmacokinetic studies confirm that a therapeutic serum concentration was achieved at a tolerable dose of 0.75 mg/kg/day. The canine patient remains without evidence of recurrent disease 24 months following initial diagnosis. CONCLUSIONS: The approach described through this illustrative case study is broadly applicable and might be used for other solid tumors in canines as well as in humans.

Low-grade fibromyxoid sarcoma of the vulva: a case report.

OBJECTIVE: The study aimed to describe a case of low-grade fibromyxoid sarcoma arising from the vulva and to discuss the diagnostic challenges, clinical management, and epidemiology of this rare malignancy. CASE: A 36-year-old woman presented to 3 separate emergency departments with complaints of a painful and slowly enlarging vulvar mass. Eventual gynecologic referral resulted in excision of a 6-cm, noncystic vulvar mass. Pathological diagnosis revealed low-grade fibromyxoid sarcoma. Later, a right radical hemivulvectomy ensured adequate margins, and 2 years later, the patient is free of recurrent and metastatic disease. CONCLUSIONS: Low-grade fibromyxoid sarcoma is a rare malignancy that may present in the lower genital tract. Definitive diagnosis is essential because low-grade fibromyxoid sarcoma may metastasize many years after diagnosis, thereby requiring indefinite clinical surveillance.

Congenital extrarenal malignant rhabdoid tumor in an infant with distal 22q11.2 deletion syndrome: the importance of SMARCB1.

Extrarenal rhabdoid tumor is a rare malignancy of infants and children, typically presenting in the soft tissue of deep, axial locations. We describe a rare dermal presentation of congenital extrarenal rhabdoid tumor in the left paraspinal region of a 6-month-old girl with germline deletion of chromosome 22q11.21q11.23. This case demonstrates that like other rhabdoid tumors, the SMARCB1 gene is also responsible for cutaneous extrarenal rhabdoid tumor oncogenesis.

Features of plexiform fibrohistiocytic tumor in skin punch biopsies: a retrospective study of 6 cases.

Plexiform fibrohistiocytic tumor (PFHT) is a mesenchymal neoplasm of intermediate malignant potential, which typically presents as a dermal or subcutaneous nodule, and is therefore often sampled by skin punch biopsy where diagnostic features may be subtle or absent. We retrospectively analyzed a series of 6 cases of PFHT to highlight for dermatopathologists the features of PFHTs useful to distinguish it from the other entities in the differential diagnosis. On the basis of the proportion of spindled fibroblastic cells to histiocytoid nodules in the biopsy specimen, we divided PFHT into 3 histologic variants: cellular, fibrous, and mixed. The biopsies also were compared with the final resection specimens, in an attempt to determine which histologic features in the original biopsies were most helpful in establishing a diagnosis. Clinical follow-up and immunohistochemistry were performed on all cases. The cellular and mixed variants were a lesser diagnostic challenge inasmuch as the distinctive features were more easily identifiable in small punch biopsy specimens. The fibrous variant proved more difficult to diagnose. Features most helpful in the diagnosis of PFHT were biphasic appearance with small, cellular, histiocytoid aggregates and accompanying plump spindled cells in the deep dermis and subcutis. Negative staining for CD34, NK1/C3, factor XIIIa, and beta-catenin by immunohistochemistry proved useful in excluding some of its mimics.

Primitive neuroectodermal tumor of the orbit in adults: a case series.

PURPOSE: To present the clinical, radiologic, and histopathologic features of orbital primitive neuroectodermal tumor (PNET) in 5 adult patients. METHODS: Retrospective case series of 5 adult patients with orbital PNET. Orbitotomy was performed in all cases. The authors report clinical findings, radiologic features, histopathology, immunohistochemical analysis, management, and outcomes for 5 patients with orbital PNET. RESULTS: Five adult patients presented with progressive unilateral proptosis and visual impairment. Common radiographic findings included a heterogeneous mass without associated destructive features, located in the superior and/or lateral orbit. Four cases demonstrated strong immunohistochemical staining for CD99 in a membranous pattern. One case required chromosomal analysis with fluorescence in situ hybridization to confirm the diagnosis. All patients received chemotherapy and/or orbital radiation with resolution of proptosis but no improvement of vision. One patient died of disease. CONCLUSIONS: To the authors' knowledge, this is the largest series of orbital PNET in adults. This tumor has an age demographic wider than previously believed and should be considered in the differential diagnosis of a hypercellular small round cell orbital tumor in both children and adults. Current treatment regimens are not standardized but typically use a similar approach to the treatment of Ewing sarcoma. Orbital PNET appears to have less propensity for metastasis compared with PNET in other locations. However, long-term aggressiveness remains to be proven.

Preclinical therapeutics ex ovo quail eggs as a biomimetic automation-ready xenograft platform.

Preclinical cancer research ranges from in vitro studies that are inexpensive and not necessarily reflective of the tumor microenvironment to mouse studies that are better models but prohibitively expensive at scale. Chorioallantoic membrane (CAM) assays utilizing Japanese quail (Coturnix japonica) are a cost-effective screening method to precede and minimize the scope of murine studies for anti-cancer efficacy and drug toxicity. To increase the throughput of CAM assays we have built and optimized an 11-day platform for processing up to 200 quail eggs per screening to evaluate drug efficacy and drug toxicity caused by a therapeutic. We demonstrate ex ovo concordance with murine in vivo studies, even when the in vitro and in vivo studies diverge, suggesting a role for this quail shell-free CAM xenograft assay in the validation of new anti-cancer agents.

Refractory alveolar rhabdomyosarcoma in an 11-year-old male.

Rhabdomyosarcoma (RMS) is a mesenchymal malignancy phenocopying muscle and is among the leading causes of death from childhood cancer. Metastatic alveolar rhabdomyosarcoma is the most aggressive subtype with an 8% 5-yr disease-free survival rate when a chromosomal fusion is present and a 29% 5-yr disease-free survival rate when negative for a fusion event. The underlying biology of PAX-fusion-negative alveolar rhabdomyosarcoma remains largely unexplored and is exceedingly rare in Li-Fraumeni syndrome patients. Here, we present the case of an 11-yr-old male with fusion-negative alveolar rhabdomyosarcoma studied at end of life with a comprehensive functional genomics characterization, resulting in identification of potential therapeutic targets for broader investigation.

Defining the Extracellular Matrix of Rhabdomyosarcoma.

Rhabdomyosarcoma (RMS) is the most common soft-tissue sarcoma of childhood with a propensity to metastasize. Current treatment for patients with RMS includes conventional systemic chemotherapy, radiation therapy, and surgical resection; nevertheless, little to no improvement in long term survival has been achieved in decades-underlining the need for target discovery and new therapeutic approaches to targeting tumor cells or the tumor microenvironment. To evaluate cross-species sarcoma extracellular matrix production, we have used murine models which feature knowledge of the myogenic cell-of-origin. With focus on the RMS/undifferentiated pleomorphic sarcoma (UPS) continuum, we have constructed tissue microarrays of 48 murine and four human sarcomas to analyze expression of seven different collagens, fibrillins, and collagen-modifying proteins, with cross-correlation to RNA deep sequencing. We have uncovered that RMS produces increased expression of type XVIII collagen alpha 1 (COL18A1), which is clinically associated with decreased long-term survival. We have also identified significantly increased RNA expression of COL4A1, FBN2, PLOD1, and PLOD2 in human RMS relative to normal skeletal muscle. These results complement recent studies investigating whether soft tissue sarcomas utilize collagens, fibrillins, and collagen-modifying enzymes to alter the structural integrity of surrounding host extracellular matrix/collagen quaternary structure resulting in improved ability to improve the ability to invade regionally and metastasize, for which therapeutic targeting is possible.

Preclinical rationale for entinostat in embryonal rhabdomyosarcoma.

BACKGROUND: Rhabdomyosarcoma (RMS) is the most common soft tissue sarcoma in the pediatric cancer population. Survival among metastatic RMS patients has remained dismal yet unimproved for years. We previously identified the class I-specific histone deacetylase inhibitor, entinostat (ENT), as a pharmacological agent that transcriptionally suppresses the PAX3:FOXO1 tumor-initiating fusion gene found in alveolar rhabdomyosarcoma (aRMS), and we further investigated the mechanism by which ENT suppresses PAX3:FOXO1 oncogene and demonstrated the preclinical efficacy of ENT in RMS orthotopic allograft and patient-derived xenograft (PDX) models. In this study, we investigated whether ENT also has antitumor activity in fusion-negative eRMS orthotopic allografts and PDX models either as a single agent or in combination with vincristine (VCR). METHODS: We tested the efficacy of ENT and VCR as single agents and in combination in orthotopic allograft and PDX mouse models of eRMS. We then performed CRISPR screening to identify which HDAC among the class I HDACs is responsible for tumor growth inhibition in eRMS. To analyze whether ENT treatment as a single agent or in combination with VCR induces myogenic differentiation, we performed hematoxylin and eosin (H&E) staining in tumors. RESULTS: ENT in combination with the chemotherapy VCR has synergistic antitumor activity in a subset of fusion-negative eRMS in orthotopic "allografts," although PDX mouse models were too hypersensitive to the VCR dose used to detect synergy. Mechanistic studies involving CRISPR suggest that HDAC3 inhibition is the primary mechanism of cell-autonomous cytoreduction in eRMS. Following cytoreduction in vivo, residual tumor cells in the allograft models treated with chemotherapy undergo a dramatic, entinostat-induced (70-100%) conversion to non-proliferative rhabdomyoblasts. CONCLUSION: Our results suggest that the targeting class I HDACs may provide a therapeutic benefit for selected patients with eRMS. ENT's preclinical in vivo efficacy makes ENT a rational drug candidate in a phase II clinical trial for eRMS.

Histologic response of dose-intense chemotherapy with preoperative hypofractionated radiotherapy for patients with high-risk soft tissue sarcomas.

BACKGROUND: The authors studied a dose-intense regimen of epirubicin and ifosfamide with hypofractionated preoperative radiotherapy for high-risk soft tissue sarcomas. The primary objective was estimation of the rate of >or=95% pathologic necrosis. METHODS: Twenty-five patients with intermediate-grade or high-grade, localized soft tissue sarcomas of the extremity or body wall measuring >5 cm were treated with epirubicin at a dose of 30 mg/m(2)/day on Days 1 to 4 and ifosfamide at a dose of 2.5 g/m(2)/day on Days 1 to 4 every 21 days for 3 preoperative and 3 postoperative cycles. A total of 28 grays of radiation was administered over 8 fractions during Cycle 2 of preoperative therapy (epirubicin was omitted). RESULTS: Sixteen patients (64%) completed all chemotherapy cycles and the average delivered dose intensity relative to intended therapy was 69%. Twenty-one patients (84%) experienced grade 4 toxicity (using the National Cancer Institute Common Terminology Criteria for Adverse Events [version 2.0]), which was predominantly hematologic. Notable toxicities included neutropenic fever (40%), ifosfamide-induced encephalopathy (24%), and grade 3/4 anemia (64%). Postoperative wound complications requiring a surgical procedure occurred in 20% of patients. The rate of >or=95% pathologic necrosis was 40% (95% confidence interval [95% CI], 21-59%). Estimates of 2-year overall and disease-free survival were 84% (95% CI, 66-100%) and 62% (95% CI, 37-86%), respectively. CONCLUSIONS: A high rate of >or=95% pathologic necrosis was noted with this aggressive chemoradiotherapy regimen. The occurrence of significant acute toxicities limited the delivery of the intended dose intensity.

Cytogenetic analysis of a hemosiderotic fibrolipomatous tumor.

Hemosiderotic fibrolipomatous tumor is an extremely rare, nonencapsulated, fatty lesion with a consistent histologic appearance that was originally considered reactive in nature. To our knowledge, there are no previous reports on the cytogenetics of this lesion. Reported here is a case of hemosiderotic fibrolipomatous tumor arising within the subcutaneous tissue of the right foot, dorsal aspect, of an otherwise healthy 35-year-old woman. Subsequent cytogenetic analysis revealed a clonal reciprocal translocation between chromosomes 1 and 10, with a further rearrangement involving this derivative chromosome 1 and chromosome 3. This, in addition to its characteristic morphology and immunophenotype, supports the neoplastic nature of this tumor and may aid in its diagnosis.

Intrapancreatic accessory spleen: mimic of pancreatic endocrine tumor diagnosed by endoscopic ultrasound-guided fine-needle aspiration biopsy.

Intrapancreatic accessory spleen forms a well-defined nodule within the tail of the pancreas and is commonly mistaken by imaging studies as a neuroendocrine tumor. We report three cases of intrapancreatic accessory spleen diagnosed by endoscopic ultrasound (EUS)-guided fine-needle aspiration (FNA) biopsy. Imaging studies showed well-circumscribed nodules in the tail of the pancreas. Two lesions were clinically suspicious for pancreatic neuroendocrine tumors and one appeared to be a cyst. EUS-guided FNA revealed predominantly small lymphocytes with a subset of histiocytes, conspicuous eosinophils, and plasma cells. There was also characteristic CD8 positive immunostaining of endothelial cells in cell block sections. We report the first series of accessory spleen in the pancreas diagnosed by EUS-guided FNA with the aid of CD8 immunostaining of splenic sinus endothelial cells.

The HDAC3-SMARCA4-miR-27a axis promotes expression of the PAX3:FOXO1 fusion oncogene in rhabdomyosarcoma.

Rhabdomyosarcoma (RMS) is the most common soft tissue sarcoma of childhood with an unmet clinical need for decades. A single oncogenic fusion gene is associated with treatment resistance and a 40 to 45% decrease in overall survival. We previously showed that expression of this PAX3:FOXO1 fusion oncogene in alveolar RMS (aRMS) mediates tolerance to chemotherapy and radiotherapy and that the class I-specific histone deacetylase (HDAC) inhibitor entinostat reduces PAX3:FOXO1 protein abundance. Here, we established the antitumor efficacy of entinostat with chemotherapy in various preclinical cell and mouse models and found that HDAC3 inhibition was the primary mechanism of entinostat-induced suppression of PAX3:FOXO1 abundance. HDAC3 inhibition by entinostat decreased the activity of the chromatin remodeling enzyme SMARCA4, which, in turn, derepressed the microRNA miR-27a. This reexpression of miR-27a led to PAX3:FOXO1 mRNA destabilization and chemotherapy sensitization in aRMS cells in culture and in vivo. Furthermore, a phase 1 clinical trial (ADVL1513) has shown that entinostat is tolerable in children with relapsed or refractory solid tumors and is planned for phase 1B cohort expansion or phase 2 clinical trials. Together, these results implicate an HDAC3-SMARCA4-miR-27a-PAX3:FOXO1 circuit as a driver of chemoresistant aRMS and suggest that targeting this pathway with entinostat may be therapeutically effective in patients.

Multiple exostosis: a short study of abnormalities near the growth plate.

The pathogenesis of multiple exostosis has been controversial with many theories put forward including the structural/mechanical theory, which emphasizes that the osteochondroma arises in the displaced growth plate cartilage penetrating a defective periosteum. Recently, molecular genetics has offered the neoplastic model with tumor suppressor genes implicated in the development and pathogenesis of exostosis. In this study, we demonstrated the spectrum of histological abnormalities in the developing exostosis present on the surface of the bone at the physis. Seven skeletally immature patients with multiple exostoses were used in this study. The patients' families were advised of and consented to the proposed study. Coincident with removal of symptomatic exostoses that was adjacent to the physis, a thin strip of bone with overlying periosteum was removed to include the edge of the physis. This was followed by formalin fixation and routine paraffin embedding. We demonstrated the earliest lesion as a microchondroma within the periosteum adjacent to the normal physis (also called the 'groove of Ranvier'). More mature progressively larger lesions showing enchondral ossification were seen distally. The periosteum and the perichondrium were intact with normal physis. Our observations give support to the fact that precursor cells in the periosteum adjacent to the physis (also called the 'groove of Ranvier') gives rise to the chondrocytes that clonally expands and develops into exostosis.