Mutations involving TGFB and MAPK may be associated with malignancy in granular cell tumors.

Granular cell tumors (GrCTs) are mesenchymal neoplasms of presumed schwannian differentiation that may present as solitary or multifocal lesions with excision usually being curative. A minority of cases, however, show histological features associated with an increased risk for metastasis and are highly aggressive leading to death in about a third of cases. While benign and malignant cases have been shown to harbor mutations in the H + ATPase genes, there is only limited data examining molecular aberrations associated with malignancy. The departmental archives were searched for cases of atypical/malignant GrCTs. Clinical and histopathological features were noted. Whole-exome sequencing was performed. Three cases of malignant GrCTs and one case of atypical GrCTs were included. All three malignant tumors metastasized to distant sites with a median disease-free survival of 16 months and an overall follow-up time of 35 months. Whole-exome sequencing showed mutations involving TGFß and MAPK pathways in all four tumors. Although the cohort size is small, our preliminary findings suggest that mutations involving the TGFß and MAPK pathways may be associated with tumor progression or malignant transformation in GrCT pathogenesis.

Treatment decisions and the use of MEK inhibitors for children with neurofibromatosis type 1-related plexiform neurofibromas.

Neurofibromatosis type 1 (NF1), the most common tumor predisposition syndrome, occurs when NF1 gene variants result in loss of neurofibromin, a negative regulator of RAS activity. Plexiform neurofibromas (PN) are peripheral nerve sheath tumors that develop in patients with NF1 and are associated with substantial morbidity and for which, until recently, the only treatment was surgical resection. However, surgery carries several risks and a proportion of PN are considered inoperable. Understanding the genetic underpinnings of PN led to the investigation of targeted therapies as medical treatment options, and the MEK1/2 inhibitor selumetinib has shown promising efficacy in pediatric patients with NF1 and symptomatic, inoperable PN. In a phase I/II trial, most children (approximately 70%) achieved reduction in tumor volume accompanied by improvements in patient-reported outcomes (decreased tumor-related pain and improvements in quality of life, strength, and range of motion). Selumetinib is currently the only licensed medical therapy indicated for use in pediatric patients with symptomatic, inoperable NF1-PN, with approval based on the results of this pivotal clinical study. Several other MEK inhibitors (binimetinib, mirdametinib, trametinib) and the tyrosine kinase inhibitor cabozantinib are also being investigated as medical therapies for NF1-PN. Careful consideration of multiple aspects of both disease and treatments is vital to reduce morbidity and improve outcomes in patients with this complex and heterogeneous disease, and clinicians should be fully aware of the risks and benefits of available treatments. There is no single treatment pathway for patients with NF1-PN; surgery, watchful waiting, and/or medical treatment are options. Treatment should be individualized based on recommendations from a multidisciplinary team, considering the size and location of PN, effects on adjacent tissues, and patient and family preferences. This review outlines the treatment strategies currently available for patients with NF1-PN and the evidence supporting the use of MEK inhibitors, and discusses key considerations in clinical decision-making.

Cell-free DNA ultra-low-pass whole genome sequencing to distinguish malignant peripheral nerve sheath tumor (MPNST) from its benign precursor lesion: A cross-sectional study.

BACKGROUND: The leading cause of mortality for patients with the neurofibromatosis type 1 (NF1) cancer predisposition syndrome is the development of malignant peripheral nerve sheath tumor (MPNST), an aggressive soft tissue sarcoma. In the setting of NF1, this cancer type frequently arises from within its common and benign precursor, plexiform neurofibroma (PN). Transformation from PN to MPNST is challenging to diagnose due to difficulties in distinguishing cross-sectional imaging results and intralesional heterogeneity resulting in biopsy sampling errors. METHODS AND FINDINGS: This multi-institutional study from the National Cancer Institute and Washington University in St. Louis used fragment size analysis and ultra-low-pass whole genome sequencing (ULP-WGS) of plasma cell-free DNA (cfDNA) to distinguish between MPNST and PN in patients with NF1. Following in silico enrichment for short cfDNA fragments and copy number analysis to estimate the fraction of plasma cfDNA originating from tumor (tumor fraction), we developed a noninvasive classifier that differentiates MPNST from PN with 86% pretreatment accuracy (91% specificity, 75% sensitivity) and 89% accuracy on serial analysis (91% specificity, 83% sensitivity). Healthy controls without NF1 (participants = 16, plasma samples = 16), PN (participants = 23, plasma samples = 23), and MPNST (participants = 14, plasma samples = 46) cohorts showed significant differences in tumor fraction in plasma (P = 0.001) as well as cfDNA fragment length (P < 0.001) with MPNST samples harboring shorter fragments and being enriched for tumor-derived cfDNA relative to PN and healthy controls. No other covariates were significant on multivariate logistic regression. Mutational analysis demonstrated focal NF1 copy number loss in PN and MPNST patient plasma but not in healthy controls. Greater genomic instability including alterations associated with malignant transformation (focal copy number gains in chromosome arms 1q, 7p, 8q, 9q, and 17q; focal copy number losses in SUZ12, SMARCA2, CDKN2A/B, and chromosome arms 6p and 9p) was more prominently observed in MPNST plasma. Furthermore, the sum of longest tumor diameters (SLD) visualized by cross-sectional imaging correlated significantly with paired tumor fractions in plasma from MPNST patients (r = 0.39, P = 0.024). On serial analysis, tumor fraction levels in plasma dynamically correlated with treatment response to therapy and minimal residual disease (MRD) detection before relapse. Study limitations include a modest MPNST sample size despite accrual from 2 major referral centers for this rare malignancy, and lack of uniform treatment and imaging protocols representing a real-world cohort. CONCLUSIONS: Tumor fraction levels derived from cfDNA fragment size and copy number alteration analysis of plasma cfDNA using ULP-WGS significantly correlated with MPNST tumor burden, accurately distinguished MPNST from its benign PN precursor, and dynamically correlated with treatment response. In the future, our findings could form the basis for improved early cancer detection and monitoring in high-risk cancer-predisposed populations.

Phase II study of pazopanib with oral topotecan in patients with metastatic and non-resectable soft tissue and bone sarcomas.

BACKGROUND: Pazopanib is active in refractory soft-tissue sarcoma (STS) and significantly prolongs PFS. Prior studies of combinations of metronomic topotecan with pazopanib have indicated preclinical evidence of response in patients with sarcoma. METHODS: This prospective, single arm, phase II study evaluated the efficacy of the combination of pazopanib with topotecan in patients with metastatic or unresectable non-adipocytic STS. Furthermore, it incorporated exploratory arms for osteosarcoma and liposarcoma. The primary endpoint was progression-free rate at 12 weeks in the non-adipocytic STS cohort. RESULTS: 57.5% of patients in the non-adipocytic STS cohort were progression free at 12 weeks, which did not meet the primary endpoint of the study (66%). The exploratory osteosarcoma cohort exceeded previously established phase II trial comparator data benchmark of 12% with a PFR at 12 weeks of 69.55%. Treatment with the combination of pazopanib and topotecan was accompanied by a grade 3 or 4 toxicities in most patients. CONCLUSIONS: In this prospective trial in refractory metastatic or unresectable STS and osteosarcoma, the combination of pazopanib with topotecan did not meet its primary endpoint of progression-free rate at 12 weeks. The combination of pazopanib with topotecan was associated with a high degree of toxicity.

Multi-institutional analysis of stereotactic body radiotherapy for sarcoma pulmonary metastases: High rates of local control with favorable toxicity.

BACKGROUND/OBJECTIVES: Oligometastatic sarcoma pulmonary metastases (PM's) are traditionally treated with resection and/or chemotherapy. We hypothesize that stereotactic body radiotherapy (SBRT) is an effective, safe alternative to surgery that can achieve excellent local control (LC) with a favorable toxicity profile. METHODS: Patients treated with SBRT for sarcoma PM's from 2011 to 2016 at Massachusetts General Hospital and the University of Pennsylvania were included. Median dose was 50 Gy. Patients underwent computed tomography (CT) or positron emission tomography/CT Q3 months post-SBRT. RESULTS: 44 patients with 56 separate PM's were treated with SBRT. Median age was 59 (range 19-82). 82% received prior chemotherapy, 66% had prior pulmonary resections (range, 1-5 resections), and 32% received prior thoracic radiotherapy. Median lesion size was 2.0 cm (range, 0.5-8.1 cm). Median follow-up was 16 months and 25 months for patients alive at last follow-up. Overall survival at 12 and 24 months was 74% (95% confidence interval [CI], 67%-81%) and 46% (95% CI, 38%-55%). LC at 12 and 24 months was 96% (95% CI, 93%-98%) and 90% (95% CI, 84%-96%). LC and overall survival did not differ based on age, gender, histology, fractionation, lesion location, or size (P > .05). Three developed Common Terminology Criteria for Adverse Events version 4 grade-2 chest-wall toxicities; one had grade-2 pneumonitis. CONCLUSIONS: In the first multi-institutional series on SBRT for sarcoma PM's, SBRT has excellent LC and is well-tolerated. SBRT should be considered as an alternative/complement to resection.

Does Advanced Imaging Have a Role in Detecting Local Recurrence of Soft-tissue Sarcoma?

BACKGROUND: Early detection of soft-tissue sarcoma recurrences may decrease the morbidity of reoperation and improve oncologic outcomes. The benefit of imaging compared with clinical surveillance for detecting local recurrences remains controversial, as prior studies have varied in terms of inclusion criteria, factors analyzed, and outcomes reported. QUESTIONS/PURPOSES: (1) What proportion of local recurrences were detected by surveillance imaging compared with clinical signs and symptoms? (2) Were local recurrences detected by imaging smaller than those detected by clinical surveillance? (3) Were relevant tumor, patient, or operative characteristics associated with clinically occult local recurrence? METHODS: Over a 20-year period ending in 2018, we treated 545 patients for soft-tissue sarcoma. During that period, we recommended that patients receive a surgical excision as well as radiation therapy based on current clinical guidelines. Of those we treated, 9% (51 of 545) were excluded for having a low-grade liposarcoma, and 4% (21 of 545) were excluded for being metastatic at the time of presentation. Of the remaining patients, 22% (107 of 473) were lost to follow-up before 2 years but were not known to have died. There were a remaining 366 patients for analysis in this retrospective study of electronic medical records from a single center. Patients routinely underwent advanced imaging and clinical follow-up at intervals based on currently available guidelines for sarcoma surveillance. We recommended that patients with high-grade sarcomas be followed every 3 months until 2 years, then every 6 months until 3 years, then annually thereafter. In contrast, we recommended that patients with low-grade sarcomas be followed every 6 months until 2 years, then annually thereafter. In addition, patients were encouraged to return for evaluation if they noted a new mass or other symptoms. In general, patients with high-grade sarcomas received postoperative radiation therapy unless they underwent amputation, while intermediate- and low-grade sarcomas were radiated according to clinical concern for local recurrence, as determined by the multidisciplinary sarcoma team. Seventeen percent (61 of 366) of patients developed or presented with a local recurrence. Of the local recurrences detected by surveillance imaging, 17 were detected by MRI, three were detected by position emission tomography, and one was detected by CT scan. The proportion of local recurrences first identified by advanced imaging versus clinical detection (physical examination, self-detection, or symptomatic presentation) were compared. Logistic regression with a Wald chi-square test was performed to evaluate if tumor, patient, or operative characteristics are associated with clinical versus imaging detection of local recurrences. RESULTS: A higher proportion of local recurrences were detected by clinical signs and symptoms than by routine imaging (66% (40 of 61) versus 34% (21 of 61), binomial proportion 0.66 [95% CI 0.55 to 0.77]; p = 0.007). With the numbers available, there was no difference in the tumor size detected by clinical signs and symptoms compared with surveillance imaging. The median (interquartile range) largest tumor dimension was 3.9 cm (2.5 to 7.8) for clinical surveillance versus 4.5 cm (2.7 to 6.2) for imaging surveillance (p = 0.98). We were unable to identify any associated factors, alone or in combination, with detection by physical exam, including patient age, tumor size, tumor depth, tumor location, operative closure type, or radiation status. Characteristics such as larger tumors, more superficial tumors, low BMI, the absence of a flap reconstruction or radiation treatment, were not associated with a greater likelihood of detection by physical examination. CONCLUSIONS: We found that although a high proportion of local recurrences were detected by clinical signs and symptoms, approximately one-third were detected by imaging. Although not all patients may benefit equally from routine imaging, we were unable to identify any patient, tumor, or operative characteristics to define a subgroup of patients that are more or less likely benefit from this surveillance technique. These findings support current surveillance guidelines that recommend the use of advanced imaging; however, other factors may also warrant consideration. Futher insight could be gained by studying surveillance imaging in terms of optimal frequency, cost-effectiveness, and psychosocial implications for patients. LEVEL OF EVIDENCE: Level III, diagnostic study.

A Phase II Study of Tumor Ablation in Patients with Metastatic Sarcoma Stable on Chemotherapy.

LESSONS LEARNED: Ablation therapy appears to be a reasonably safe and effective approach to obtain a significant treatment-free interval for a subset of patients with limited sites of metastatic disease for which systemic control can be obtained with six cycles of chemotherapy. BACKGROUND: Metastatic sarcoma often becomes resistant to treatment by chemotherapy. There is sometimes prolonged stable disease from active chemotherapy that provides a window of opportunity for an intervention to prolong disease-free survival. MATERIALS AND METHODS: We performed a phase II study in patients with metastatic sarcoma who had been stable on six cycles of chemotherapy who then received ablation therapy to their residual disease. Histologies captured in this study included leiomyosarcoma, malignant peripheral nerve sheath tumor, pleiomorphic rhabdomyosarcoma, and myxoid liposarcoma. Sites ablated included lung metastases and retroperitoneal metastatic deposits. In this study, up to three lesions were ablated in any given interventional radiology session. After ablation, patients were not treated with any further therapy but were followed by surveillance imaging to determine progression-free rate (PFR). RESULTS: Although terminated early because of slow accrual, this study demonstrated a 3-month PFR of 75% for this cohort of eight patients treated with ablation performed after completion of six cycles of chemotherapy with stable disease. Median progression-free survival (PFS) was 19.74 months, and the median overall survival (OS) was not reached. CONCLUSION: Our data are the first prospective study to suggest that ablation therapy in selected patients who are stable on chemotherapy can provide a significant progression-free interval off therapy and warrants further study in a randomized trial.

Diagnosis and Treatment of Myxoid Liposarcomas: Histology Matters.

OPINION STATEMENT: Sarcomas are a heterogeneous group of rare malignancies that arise from mesenchymal cells and can occur anywhere in the body. Herein, the focus will be on one subtype of sarcoma that arises from adipocytic tissue, liposarcoma. Specifically, the review will focus on one type of liposarcoma, myxoid liposarcoma. Given the rarity of this tumor, it is imperative that these patients are treated at a sarcoma center, where a multidisciplinary approach incorporates all the modalities available including clinical trials. As the understanding of the biology of myxoid liposarcomas progresses, more targeted therapies are being developed that will lead to better tolerated treatments and improved survival for patients. In this review, we will be discussing the pathophysiology, clinical presentation, diagnostic workup, and available treatment options including surgery, radiation, chemotherapy, and clinical trials.

Clinical genomic profiling identifies TYK2 mutation and overexpression in patients with neurofibromatosis type 1-associated malignant peripheral nerve sheath tumors.

BACKGROUND: Malignant peripheral nerve sheath tumors (MPNSTs) are aggressive sarcomas that arise at an estimated frequency of 8% to 13% in individuals with neurofibromatosis type 1 (NF1). Compared with their sporadic counterparts, NF1-associated MPNSTs (NF1-MPNSTs) develop in young adults, frequently recur (approximately 50% of cases), and carry a dismal prognosis. As such, most individuals affected with NF1-MPNSTs die within 5 years of diagnosis, despite surgical resection combined with radiotherapy and chemotherapy. METHODS: Clinical genomic profiling was performed using 1000 ng of DNA from 7 cases of NF1-MPNST, and bioinformatic analyses were conducted to identify genes with actionable mutations. RESULTS: A total of 3 women and 4 men with NF1-MPNST were identified (median age, 38 years). Nonsynonymous mutations were discovered in 4 genes (neurofibromatosis type 1 [NF1], ROS proto-oncogene 1 [ROS1], tumor protein p53 [TP53], and tyrosine kinase 2 [TYK2]), which in addition were mutated in other MPNST cases in this sample set. Consistent with their occurrence in individuals with NF1, all tumors had at least 1 mutation in the NF1 gene. Whereas TP53 gene mutations are frequently observed in other cancers, ROS1 mutations are common in melanoma (15%-35%), another neural crest-derived malignancy. In contrast, TYK2 mutations are uncommon in other malignancies (<7%). In the current series, recurrent TYK2 mutations were identified in 2 cases of NF1-MPNST (30% of cases), whereas TYK2 protein overexpression was observed in 60% of MPNST cases using an independently generated tissue microarray, regardless of NF1 status. CONCLUSIONS: Clinical genomic analysis of the current series of NF1-MPNST cases found that TYK2 is a new gene mutated in MPNST. Future work will focus on examining the utility of TYK2 expression as a biomarker and therapeutic target for these cancers. Cancer 2017;123:1194-1201. © 2016 American Cancer Society.

Morphologic and immunohistochemical features of malignant peripheral nerve sheath tumors and cellular schwannomas.

Cellular schwannoma is an uncommon, but well-recognized, benign peripheral nerve sheath tumor, which can be misdiagnosed as malignant peripheral nerve sheath tumor. To develop consensus diagnostic criteria for cellular schwannoma, we reviewed 115 malignant peripheral nerve sheath tumor and 26 cellular schwannoma cases from two institutions. Clinical data were retrieved from the electronic medical records, and morphologic features, maximal mitotic counts, Ki67 labeling indices, and immunohistochemical profiles (SOX10, SOX2, p75NTR, p16, p53, EGFR, and neurofibromin) were assessed. Several features distinguish cellular schwannoma from malignant peripheral nerve sheath tumor. First, in contrast to patients with malignant peripheral nerve sheath tumor, no metastases or disease-specific deaths were found in patients with cellular schwannoma. More specifically, 5-year progression-free survival rates were 100 and 18%, and 5-year disease-specific survival rates were 100 and 32% for cellular schwannoma and malignant peripheral nerve sheath tumor, respectively. Second, the presence of Schwannian whorls, a peritumoral capsule, subcapsular lymphocytes, macrophage-rich infiltrates, and the absence of fascicles favored the diagnosis of cellular schwannoma, while the presence of perivascular hypercellularity, tumor herniation into vascular lumens, and necrosis favor malignant peripheral nerve sheath tumor. Third, complete loss of SOX10, neurofibromin or p16 expression, or the presence of EGFR immunoreactivity was specific for malignant peripheral nerve sheath tumor (P<0.001 for each). Expression of p75NTR was observed in 80% of malignant peripheral nerve sheath tumors compared with 31% of cellular schwannomas (P<0.001). Fourth, Ki-67 labeling indices ≥20% were highly predictive of malignant peripheral nerve sheath tumor (87% sensitivity and 96% specificity). Taken together, the combinations of these histopathological and immunohistochemical features provide useful criteria to distinguish between malignant peripheral nerve sheath tumor and cellular schwannoma with high sensitivity and specificity. Additional retrospective and prospective multicenter studies with larger data sets will be required to validate these findings.

Malignant Peripheral Nerve Sheath Tumor, a Heterogeneous, Aggressive Cancer with Diverse Biomarkers and No Targeted Standard of Care: Review of the Literature and Ongoing Investigational Agents.

BACKGROUND: Malignant peripheral sheath tumor (MPNST) is a rare, aggressive form of soft-tissue sarcoma that presents a unique set of diagnostic and treatment challenges and is associated with major unmet treatment medical needs. OBJECTIVE: The chief aim of this review is to consider the epidemiology, histology, anatomic distribution, pathologic signaling pathways, diagnosis, and management of MPNST, with a focus on potential targeted therapies. A subordinate objective was to establish benchmarks for the antitumor activity of such treatments. RESULTS: MPNST has an incidence of 1:100,000 in the general population and 1:3500 among patients with the inherited condition of neurofibromatosis-1. Spindle-cell sarcomas of neural-crest origin, MPNSTs are frequently situated in the extremities and pelvis/trunk, often at the confluence of large nerve roots and bundles. Highly copy-number aberrant and enriched in chromosome 8, MPNSTs have a complex molecular pathogenesis that likely involves the interplay of multiple signaling pathways, including Ras/AKT/mTOR/MAPK, EGFR, p53, PTEN, and PRC2, as well as factors in the tumor microenvironment. A combination of magnetic resonance imaging (MRI) and positron emission tomography with 18F-fluorodeoxyglucose (FDG-PET) enables comprehensive assessment of both morphology and metabolism, while MRI- and ultrasound-guided core needle biopsy can confirm histopathology. Although surgery with wide excisional margins is now the chief curative approach to localized disease, MPNST-specific survival has not improved in decades. For advanced and metastatic MPNST, radiation and chemotherapy (chiefly with anthracyclines plus ifosfamide) have somewhat promising but still largely uncertain treatment roles, chiefly in local control, downstaging, and palliation. No single druggable target has emerged, no objective responses have been observed with a number of targeted therapies (cumulative disease control rate in our review = 22.9-34.8%), and combinatorial approaches directed toward multiple signal transduction mechanisms are hallmarks of ongoing clinical trials. CONCLUSIONS: Despite advances in our understanding of the genetics and molecular biology of MPNST, further research is warranted to: (1) unravel the complex pathogenesis of this condition; (2) improve diagnostic yield; (3) delineate the appropriate roles of chemotherapy and radiation; and (4) develop a targeted therapy (or combination of such treatments) that is well tolerated and prolongs survival.

CSF1 expression in xanthogranulomatous epithelial tumor/keratin-positive giant cell-rich tumor.

"Xanthogranulomatous epithelial tumor" (XGET) and "keratin-positive giant cell-rich soft tissue tumor" (KPGCT), two recently described mesenchymal neoplasms, likely represent different aspects of a single entity. Both tumors are composed of only a small minority of tumor cells surrounded by large numbers of non-neoplastic inflammatory cells and histiocytes, suggesting production of a paracrine factor with resulting "landscape effect," as seen in tenosynovial giant cell tumor. Recent evidence suggests that the paracrine factor in XGET/KPGCT may be CSF1, as in tenosynovial giant cell tumor. We hypothesized that CSF1 is overexpressed in XGET/KPGCT. To test our hypothesis, we performed quantitative real time PCR (qPCR) for CSF1 expression and CSF1 RNAscope chromogenic in situ hybridization (CISH) on 6 cases of XGET/KPGCT. All cases were positive with CSF1 CISH and showed increased expression of CSF1 by qPCR. Our findings provide additional evidence that the CSF1/CSF1R pathway is involved in the pathogenesis of XGET/KPGCT. These findings suggest a possible role for CSF1R inhibition in the treatment of unresectable or metastatic XGET/KPGCT.

Contemporary Approach to Neurofibromatosis Type 1-Associated Malignant Peripheral Nerve Sheath Tumors.

Most malignant peripheral nerve sheath tumors (MPNSTs) are clinically aggressive high-grade sarcomas, arising in individuals with neurofibromatosis type 1 (NF1) at a significantly elevated estimated lifetime frequency of 8%-13%. In the setting of NF1, MPNSTs arise from malignant transformation of benign plexiform neurofibroma and borderline atypical neurofibromas. Composed of neoplastic cells from the Schwannian lineage, these cancers recur in approximately 50% of individuals, and most patients die within five years of diagnosis, despite surgical resection, radiation, and chemotherapy. Treatment for metastatic disease is limited to cytotoxic chemotherapy and investigational clinical trials. In this article, we review the pathophysiology of this aggressive cancer and current approaches to surveillance and treatment.

Systemic delivery of murine SOD2 mRNA to experimental abdominal aortic aneurysm mitigates expansion and rupture.

Background: Oxidative stress is implicated in the pathogenesis and progression of abdominal aortic aneurysm (AAA). Antioxidant delivery as a therapeutic for AAA is of substantial interest although clinical translation of antioxidant therapy has met with significant challenges due to limitations in achieving sufficient antioxidant levels at the site of AAA. We posit that nanoparticle-based approaches hold promise to overcome challenges associated with systemic administration of antioxidants. Methods: We employed a peptide-based nanoplatform to overexpress a key modulator of oxidative stress, superoxide dismutase 2 (SOD2). The efficacy of systemic delivery of SOD2 mRNA as a nanotherapeutic agent was studied in two different murine AAA models. Unbiased mass spectrometry-enabled proteomics and high-dimensional bioinformatics were used to examine pathways modulated by SOD2 overexpression. Results: The murine SOD2 mRNA sequence was mixed with p5RHH, an amphipathic peptide capable of delivering nucleic acids in vivo to form self-assembled nanoparticles of ∼55 nm in diameter. We further demonstrated that the nanoparticle was stable and functional up to four weeks following self-assembly when coated with hyaluronic acid. Delivery of SOD2 mRNA mitigated the expansion of small AAA and largely prevented rupture. Mitigation of AAA was accompanied by enhanced SOD2 protein expression in aortic wall tissue. Concomitant suppression of nitric oxide, inducible nitric oxide synthase expression, and cell death was observed. Proteomic profiling of AAA tissues suggests that SOD2 overexpression augments levels of microRNAs that regulate vascular inflammation and cell apoptosis, inhibits platelet activation/aggregation, and downregulates mitogen-activated protein kinase signaling. Gene set enrichment analysis shows that SOD2 mRNA delivery is associated with activation of oxidative phosphorylation, lipid metabolism, respiratory electron transportation, and tricarboxylic acid cycle pathways. Conclusions: These results confirm that SOD2 is key modulator of oxidative stress in AAA. This nanotherapeutic mRNA delivery approach may find translational application in the medical management of small AAA and the prevention of AAA rupture.

A Single Arm Phase 2 Trial of Trametinib in Patients With Locally Advanced or Metastatic Epithelioid Hemangioendothelioma.

PURPOSE: Epithelioid hemangioendothelioma (EHE) is a rare vascular cancer with pathogenic TAZ-CAMTA1 operating as an oncogenic driver through activation of MAPK pathway. Trametinib is an inhibitor of MEK, a critical kinase in the MAPK pathway. We sought to evaluate the effect of trametinib in patients with EHE. PATIENTS AND METHODS: A phase 2 trial of trametinib was conducted in patients with locally advanced or metastatic EHE. Eligibility requirements included evidence of tumor progression or presence of EHE-related pain requiring opiates for management prior to enrollment. The primary endpoint was objective response rate (ORR) per RECIST1.1 in cases with TAZ-CAMTA1 confirmed by fusion-FISH. Secondary objectives were to estimate ORR for all patients, median PFS, 2-year OS rate, patient safety, and change in patient-reported global health and pain scores per PROMIS questionnaires. RESULTS: 44 patients enrolled and 42 started trametinib. TAZ-CAMTA1 was detected in 27 tumor samples. The ORR was 3.7% (95% CI: 0.094, 19.0), median PFS was 10.4 months (95% CI: 7.1, NA), and 2-year OS rate was 33.3% (95% CI: 19.1, 58.2) in the target population. Median pain intensity and interference scores improved significantly after 4 weeks of trametinib in patients using opiates. Common AEs related to trametinib were rash, fatigue, nausea/vomiting, diarrhea/constipation, alopecia and edema; one Grade 5 ARDS/pneumonitis was related to trametinib. CONCLUSIONS: Trametinib was associated with reduction in EHE-related pain and median PFS of more than 6 months providing palliative benefit in patients with advanced EHE, but the trial did not meet the ORR goal.

Early detection of malignant and pre-malignant peripheral nerve tumors using cell-free DNA fragmentomics.

Early detection of neurofibromatosis type 1 (NF1) associated peripheral nerve sheath tumors (PNST) informs clinical decision-making, potentially averting deadly outcomes. Here, we describe a cell-free DNA (cfDNA) fragmentomic approach which distinguishes non-malignant, pre-malignant and malignant forms of NF1 PNST. Using plasma samples from a novel cohort of 101 NF1 patients and 21 healthy controls, we validated that our previous cfDNA copy number alteration (CNA)-based approach identifies malignant peripheral nerve sheath tumor (MPNST) but cannot distinguish among benign and premalignant states. We therefore investigated the ability of fragment-based cfDNA features to differentiate NF1-associated tumors including binned genome-wide fragment length ratios, end motif analysis, and non-negative matrix factorization deconvolution of fragment lengths. Fragmentomic methods were able to differentiate pre-malignant states including atypical neurofibromas (AN). Fragmentomics also adjudicated AN cases suspicious for MPNST, correctly diagnosing samples noninvasively, which could have informed clinical management. Overall, this study pioneers the early detection of malignant and premalignant peripheral nerve sheath tumors in NF1 patients using plasma cfDNA fragmentomics. In addition to screening applications, this novel approach distinguishes atypical neurofibromas from benign plexiform neurofibromas and malignant peripheral nerve sheath tumors, enabling more precise clinical diagnosis and management.

Novel pathways and molecular targets for the treatment of sarcoma.

Sarcomas collectively represent over 100 different subtypes of bone and soft tissue tumors of mesenchymal origin. The low response rate to cytotoxic chemotherapies has necessitated the need for development of either histologically driven or pathway-specific targeted therapies. As our understanding of the molecular mechanisms driving certain subtypes is rapidly advancing, the number of targeted therapies is also increasing. Recently identified novel druggable targets include the MDM2 amplifications in well-differentiated and dedifferentiated liposarcomas, the new translocation NAB2:STAT6 of solitary fibrous tumors, the angiopoeitin-TIE2 pathway in angiosarcoma, the suppression of Mcl1 in X:18/synovial sarcomas, the mTOR pathway in malignant peripheral nerve sheath tumors, CDK4 in alveolar rhabdomyosarcoma, cMET regulation in alveolar soft parts sarcoma, the metabolic abnormalities in wild-type/SHD GIST, and the lack of argininosuccinate synthetase 1 expression seen in most sarcomas. It is through a fundamental understanding of sarcoma biology that clinical trials based on molecular targets can be developed.

Molecular Characterization of Multifocal Granular Cell Tumors.

Granular cell tumors (GrCT) were recently found to be driven by inactivating mutations in vacuolar H + -ATPase (V-ATPase) genes, most frequently ATP6AP1 and ATP6AP2 . Multifocal presentation is present in ~10% of cases; however, the relationship between multifocal tumors in a given patient has not been elucidated. We hypothesized that benign-appearing multifocal GrCT are molecularly distinct whereas paired primary and metastatic malignant GrCT share identical mutations. To test this, we conducted targeted next-generation sequencing of the V-ATPase genes in multifocal GrCT and whole exome and Sanger sequencing in paired primary and metastatic malignant GrCT. Thirteen patients with≥2 GrCT were identified (total of 43 tumors). Forty-two tumors were successfully sequenced. Tumors showed somatic mutations in 3 of the 10 targeted genes in 32 of 42 samples (76%). Twenty tumors showed mutations in ATP6AP1 (48%), 10 tumors had mutations in ATP6AP2 (24%), and 2 tumors showed mutations in ATP6V0A4 (5%). Predicted loss-of-function mutations were found in ATP6AP1 in 17 tumors (40%), in ATP6AP2 in 10 tumors (24%), and in ATP6V0A4 in 1 tumor (2%). In 8 patients, mutually exclusive mutations were detected in at least 2 tumors per patient. Two patients were identified with malignant GrCT with material available from both primary and metastatic sites. Identical frameshift insertions were found in ATP6AP1 in 1 case and the second case showed identical nonsense mutations in ATP6AP1 . In conclusion, multifocal GrCT within an individual patient are molecularly distinct, while paired primary and metastatic GrCT share identical mutations.

Loss of Chromosome 3q Is a Prognostic Marker in Fusion-Negative Rhabdomyosarcoma.

PURPOSE: Soft tissue sarcomas (STS) are rare mesenchymal neoplasms that frequently show complex chromosomal aberrations such as amplifications or deletions of DNA sequences or even whole chromosomes. We recently found that gain of chromosome (chr) 8 is associated with worse overall survival (OS) in STS as a group. We therefore aimed to investigate the overall copy number profile of rhabdomyosarcoma (RMS) to evaluate for prognostic signatures. METHODS: Fluorescence in situ hybridization (FISH) testing was performed on a cohort of STS to assess for chr8 gain. Copy number variation (CNV) data from the National Cancer Institute were analyzed to assess for prognostically significant CNV aberrations in FOXO1 fusion-negative (FN)- versus fusion-positive (FP)-RMS. FISH testing was performed on a cohort of FN-RMS to assess for chr3q loss and correlate with outcomes. RESULTS: Chr8 gain is a highly prevalent CNV in embryonal RMS and shows slightly improved prognosis. Meanwhile, loss of chr3q was associated with worse outcome in FN-RMS compared with FP-RMS. CONCLUSION: The pathogenesis of STS including FN-RMS remains poorly understood, emphasizing the need for new therapeutic advances and adequate risk stratification. Our data demonstrate that loss of chr3q is associated with poor OS in FN-RMS, supporting it as an important tool for risk stratification.

MEK Inhibition Synergizes with TYK2 Inhibitors in NF1-Associated Malignant Peripheral Nerve Sheath Tumors.

PURPOSE: Malignant peripheral nerve sheath tumors (MPNST) are aggressive sarcomas with limited treatment options and poor survival rates. About half of MPNST cases are associated with the neurofibromatosis type 1 (NF1) cancer predisposition syndrome. Overexpression of TYK2 occurs in the majority of MPNST, implicating TYK2 as a therapeutic target. EXPERIMENTAL DESIGN: The effects of pharmacologic TYK2 inhibition on MPNST cell proliferation and survival were examined using IncuCyte live cell assays in vitro, and downstream actions were analyzed using RNA-sequencing (RNA-seq), qPCR arrays, and validation of protein changes with the WES automated Western system. Inhibition of TYK2 alone and in combination with MEK inhibition was evaluated in vivo using both murine and human MPNST cell lines, as well as MPNST PDX. RESULTS: Pharmacologic inhibition of TYK2 dose-dependently decreased proliferation and induced apoptosis over time. RNA-seq pathway analysis on TYK2 inhibitor-treated MPNST demonstrated decreased expression of cell cycle, mitotic, and glycolysis pathways. TYK2 inhibition resulted in upregulation of the MEK/ERK pathway gene expression, by both RNA-seq and qPCR array, as well as increased pERK1/2 levels by the WES Western system. The compensatory response was tested with dual treatment with TYK2 and MEK inhibitors, which synergistically decreased proliferation and increased apoptosis in vitro. Finally, combination therapy was shown to inhibit growth of MPNST in multiple in vivo models. CONCLUSIONS: These data provide the preclinical rationale for the development of a phase I clinical trial of deucravacitinib and mirdametinib in NF1-assosciated MPNST.