Malignant peripheral nerve sheath tumors in children, adolescents, and young adults: Treatment results of five Cooperative Weichteilsarkom Studiengruppe (CWS) trials and one registry

Ovarian epithelioid malignant peripheral nerve sheath tumor with EWSR1-CREM fusion: A case report and literature review

Epithelioid malignant peripheral nerve sheath tumor (EMPNST) is a rare soft tissue sarcoma. The authors report the first case of EMPNST arising in the ovary (OEMPNST). A 7-year-old child underwent left salpingo-oophorectomy due to tumor rupture and the pathology suggested a juvenile granulosa cell tumor (JGCT). Six cycles of bleomycin, etoposide, and carboplatin were administrated. A second surgery was applied due to relapse 4 months after the last cycle of chemotherapy, and the pathology revealed JGCT with extensive abdominopelvic seedings even after interinstitutional consultation in two hospitals. Next-generation sequencing demonstrated EWSR1 exon12-CREM exon6 fusion with neurofibromatosis-2 gene deletion, and no mutation was detected in either FOXL2 or DICER1. However, pathology consultation in two other hospitals suggested the diagnosis of OEMPNST, and additional immunohistochemical (IHC) staining revealed positive H3K27me3. Nonetheless, she was treated with nine courses of chemotherapy but experienced a second recurrence of extensive abdominal metastases approximately 3 months after ceasing chemotherapy. Neither elevated tumor makers nor abnormal sex hormones level was noted since the initial presentation. Repeated cytoreductive surgery was conducted and IHC staining showed expression of SOX10, S-100, INI-1, and α-inhibin in tumor tissue. A final diagnosis of OEMPNST with EWSR1-CREM fusion was established, indicating that the probability of OEMPNST could not be excluded when treatment for JGCT showed poor response. A comprehensive evaluation including biological characteristics, morphology, IHC staining, and molecular features is vital in the differential diagnosis between JGCT and OEMPNST.

Malignant peripheral nerve sheath tumor in children: A clinicopathologic and molecular study with parallels to the adult counterpart

Malignant peripheral nerve sheath tumors (MPNST) are aggressive neoplasms, arising either sporadically, in the setting of neurofibromatosis type I (NF1) or post radiation. Most MPNST occur in adults and their pathogenesis is driven by the loss of function mutations in the PRC2 complex, regardless of their clinical presentation. In contrast, pediatric MPNST are rare and their pathogenesis has not been elucidated. In this study, we investigate a large cohort of 64 MPNSTs arising in children and young adults (younger than the age of 20 years) to better define their clinicopathologic and molecular features. Sixteen (25%) cases were investigated by MSK-IMPACT, a targeted NGS panel of 505 cancer genes. Most patients (80%) were aged 11-20 years. A history of NF1 was established in half of the cases. Mean tumor size was 8.5 cm. The most common locations included the extremities (34%) and abdomen/pelvis (27%). Histologically, 89% of high-grade MPNST showed conventional features, while the remaining three cases showed a predominant epithelioid phenotype. Heterologous differentiation occurred in 25% of high grade cases, with half showing rhabdomyoblastic differentiation. Tumors arose in a background of a plexiform neurofibroma (16%), neurofibroma (13%), and schwannoma in two cases (3%). Immunohistochemically, H3K27me3 expression was lost in 82% of conventional high-grade MPNST analyzed, while loss of SMARCB1 expression was seen in one epithelioid MPNST. Genomically, all cases showed more than one genetic abnormality, with 53% showing mutations in EED / SUZ12 genes, and 47% of cases harboring alterations in NF1 and CDKN2A/CDKN2B genes. At the last follow-up, 30% patients died of disease, 28% were alive with disease and 42% had no evidence of disease. NF1 status did not correlate with overall survival. In conclusion, half of pediatric and young adult MPNST were NF1-related and showed loss of function alterations in PRC2 complex, NF1, and CDKN2A, similar to the adult counterpart. Thus, H3K27me3 loss of expression may be used in the diagnosis of high grade MPNSTs in children. Moreover, a small subset of pediatric MPNST have an epithelioid morphology with different pathogenesis.

Role of perioperative chemotherapy and radiotherapy for localized high-grade malignant peripheral nerve sheath tumor at the extremities and trunk wall: a population-based cohort study

BACKGROUND

Primary tumor resection is the mainstay of treatment for malignant peripheral nerve sheath tumors. However, the efficacy of perioperative chemotherapy and radiotherapy for malignant peripheral nerve sheath tumors has not been elucidated.

METHODS

This retrospective analysis based on a Japanese registry included patients with localized malignant peripheral nerve sheath tumors arising at the extremities and trunk wall. Disease-specific overall survival and local recurrence-free survival were estimated using the Kaplan-Meier method. A Cox regression model was used to identify prognostic factors. Characteristics of groups with or without chemotherapy were adjusted using propensity score matching.

RESULTS

In total, 291 patients were included. The 5-year disease-specific overall survival rate was 70.6%. Multivariate analysis of disease-specific overall survival revealed that deep-seated tumors were a poor prognostic factor, but perioperative chemotherapy was not associated with disease-specific overall survival (hazard ratio, 0.81; 95% confidence interval, 0.45-1.43, P = 0.46). Local recurrence was observed in 55 patients (19.0%), and surgical margins (R1 and R2) were significant risk factors. Overall, perioperative chemotherapy did not prolong disease-specific overall survival (5-year disease-specific overall survival: 74.1% vs. 69.3%, P = 0.75) and had limited efficacy in the group with tumor size ≥ 5 cm, although the difference was not statistically significant (5-year disease-specific overall survival: 77.2% vs. 68.6%, respectively, P = 0.13). After adjustment by propensity score matching, perioperative chemotherapy significantly prolonged disease-specific overall survival (5-year disease-specific overall survival: 74.9% vs. 57.1%, P = 0.03), but this effect was not observed in local recurrence-free survival. In all patients, perioperative radiotherapy did not correlate with local recurrence-free survival (hazard ratio, 1.43; 95% confidence interval 0.78-2.62, P = 0.25).

CONCLUSIONS

Perioperative chemotherapy had limited efficacy for disease-specific overall survival in patients with localized malignant peripheral nerve sheath tumors.

Lessons learned from drug trials in neurofibromatosis: A systematic review

Neurofibromatosis (NF) is the umbrella term for neurofibromatosis type 1 (NF1), neurofibromatosis type 2 (NF2) and schwannomatosis (SWN). EU-PEARL aims to create a framework for platform trials in NF. The aim of this systematic review is to create an overview of recent clinical drug trials in NF, to identify learning points to guide development of the framework. We searched Embase, Medline and Cochrane register of trials on October 1, 2020 for publications of clinical drug trials in NF patients. We excluded publications published before 2010, systematic reviews, secondary analyses and studies with <10 patients. Data was extracted on manifestations studied, study design, phase, number of participating centres and population size. Full-text review resulted in 42 articles: 31 for NF1, 11 for NF2, none for SWN. Most NF1 trials focused on plexiform neurofibromas (32%). Trials in NF2 solely studied vestibular schwannomas. In NF1, single-arm trials (58%) were most common, and the majority was phase II (74%). For NF2 most trials were single-arm (55%) and exclusively phase II. For both diseases, trials were predominantly single-country and included five centres or less. Study population sizes were small, with the majority including ≤50 patients (74%). In conclusion, NF research is dominated by studies on a limited number out of the wide range of manifestations. We need more trials for cutaneous manifestations and high-grade gliomas in NF1, manifestations other than vestibular schwannoma in NF2 and trials for SWN. Drug development in NF may profit from innovative trials on multiple interventions and increased international collaboration.

High Expression of Solute Carrier Family 2 Member 1 (SLC2A1) in Cancer Cells Is an Independent Unfavorable Prognostic Factor in Pediatric Malignant Peripheral Nerve Sheath Tumor

Malignant peripheral nerve sheath tumor (MPNST) in children is a rare mesenchymal malignancy developing predominantly in the setting of neurofibromatosis type 1. The prognosis in advanced MPNST is poor therefore new prognostic markers are highly needed for optimal therapeutic decisions. In many solid tumors, the bidirectional interactions between hypoxia and inflammation in the tumor microenvironment via functions of tumor-associated cells, like neutrophils, lymphocytes and macrophages, have been investigated recently. There is no data whether in MPNST hypoxic microenvironment may translate into systemic inflammation, which is a well-established factor for worse prognosis in cancer patients. Therefore, we investigated the prognostic significance of markers of tumor hypoxia and systemic inflammation in 26 pediatric malignant peripheral nerve sheath tumors (MPNST). Tumor tissue microarrays were stained for hypoxia-inducible factor-1α (HIF1A), solute carrier family 2 member 1 (SLC2A1, also known as glucose transporter 1 (GLUT1)), carbonic anhydrase 9 (CA9), and vascular endothelial growth factor A (VEGFA) and classified into low- or high-expression groups. Baseline complete blood counts and C-reactive protein (CRP) levels were collected for all cases. Neutrophil-to-lymphocyte ratio (NLR), platelet-to-lymphocyte ratio (PLR), and lymphocyte-to-monocyte ratio (LMR) were calculated from age-adjusted complete blood count parameters. Both 10-year RFS and OS were significantly lower in patients with high NLR values (17% vs. 75%, p = 0.009, q = 0.018; and 31% vs. 100%, p = 0.0077, q = 0.014; respectively). Ten-year-OS was significantly lower in patients with high expression of SLC2A1 (20.00% vs. 94%, p < 0.001, log-rank), high expression of HIF1A (23% vs. 79%, p = 0.016, log-rank), and CRP higher than 31 mg/L (11% vs. 82%, p = 0.003, q = 0.009). Cox's proportional hazard regression analysis revealed that high expression of SLC2A1 (HR = 3.31, 95% CI = 1.08-10.09, p = 0.036) and VEGFA (HR = 4.40, 95% CI = 0.95-20.34, p = 0.058) were the independent factors predicting relapse, whereas high SLC2A1 was identified as the independent risk factor for death (HR = 12.20, 95% CI = 2.55-58.33, p = 0.002). Patients with high expression of hypoxic markers and low or high NLR/CRP values had the highest events rate, patients with low hypoxic markers and high NLR/CRP had intermediate events rate, while patients with low hypoxic markers and low NLR/CRP had the lowest events rate. SLC2A1 and VEGFA are promising novel prognostic factors in pediatric MPNST. Correlations between hypoxic and systemic inflammatory markers suggest the interplay between local tumor hypoxia and systemic inflammation.