First-line chemotherapy for malignant peripheral nerve sheath tumor (MPNST) versus other histological soft tissue sarcoma subtypes and as a prognostic factor for MPNST: an EORTC soft tissue and bone sarcoma group study

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.

Malignant perineurioma derived from the retroperitoneum with an aggressive clinical course: a case report

BACKGROUND

Malignant perineurioma is a rare malignant counterpart of perineurioma derived from perineural cells. Resection is the primary option for the treatment of malignant perineuriomas; however, patients often develop recurrence after resection, and effective treatment for advanced or recurrent lesions needs to be established. This report describes a 51-year-old female with a rare malignant perineurioma in the retroperitoneum, which contributing valuable insights to the literature.

CASE PRESENTATION

The patient presented with abdominal distension and the imaging work-up revealed a huge hemorrhagic tumor in the retroperitoneum and obstruction of inferior vena cava by the tumor. The patient underwent surgery retrieving the tumor combined with left hemiliver and retrohepatic vena cava, which confirmed the diagnosis of a malignant perineurioma based on histopathological and immunohistochemical examination. Cancer gene panel testing identified mutations in NF2. Radiotherapy was administered for peritoneal dissemination 2 months after surgery, and the patient died from disease progression 6 months after surgery.

CONCLUSIONS

This rare case highlights the challenges in managing retroperitoneal malignant perineuriomas. The aggressive characteristics and limited treatment options for advanced malignant perineuriomas underscore the need for understanding the pathogenesis and developing effective systemic therapies. The identification of an NF2 mutation provides significant insights into potential therapeutic target.

PRRX1-TOP2A interaction is a malignancy-promoting factor in human malignant peripheral nerve sheath tumours

BACKGROUND

Paired related-homeobox 1 (PRRX1) is a transcription factor in the regulation of developmental morphogenetic processes. There is growing evidence that PRRX1 is highly expressed in certain cancers and is critically involved in human survival prognosis. However, the molecular mechanism of PRRX1 in cancer malignancy remains to be elucidated.

METHODS

PRRX1 expression in human Malignant peripheral nerve sheath tumours (MPNSTs) samples was detected immunohistochemically to evaluate survival prognosis. MPNST models with PRRX1 gene knockdown or overexpression were constructed in vitro and the phenotype of MPNST cells was evaluated. Bioinformatics analysis combined with co-immunoprecipitation, mass spectrometry, RNA-seq and structural prediction were used to identify proteins interacting with PRRX1.

RESULTS

High expression of PRRX1 was associated with a poor prognosis for MPNST. PRRX1 knockdown suppressed the tumorigenic potential. PRRX1 overexpressed in MPNSTs directly interacts with topoisomerase 2 A (TOP2A) to cooperatively promote epithelial-mesenchymal transition and increase expression of tumour malignancy-related gene sets including mTORC1, KRAS and SRC signalling pathways. Etoposide, a TOP2A inhibitor used in the treatment of MPNST, may exhibit one of its anticancer effects by inhibiting the PRRX1-TOP2A interaction.

CONCLUSION

Targeting the PRRX1-TOP2A interaction in malignant tumours with high PRRX1 expression might provide a novel tumour-selective therapeutic strategy.

Pharmacogenomic synthetic lethal screens reveal hidden vulnerabilities and new therapeutic approaches for treatment of NF1-associated tumors

Neurofibromatosis Type 1 (NF1) is a common cancer predisposition syndrome, caused by heterozygous loss of function mutations in the tumor suppressor gene NF1. Individuals with NF1 develop benign tumors of the peripheral nervous system (neurofibromas), originating from the Schwann cell linage after somatic loss of the wild type NF1 allele, some of which progress further to malignant peripheral nerve sheath tumors (MPNST). There is only one FDA approved targeted therapy for symptomatic plexiform neurofibromas and none approved for MPNST. The genetic basis of NF1 syndrome makes associated tumors ideal for using synthetic drug sensitivity approaches to uncover therapeutic vulnerabilities. We developed a drug discovery pipeline to identify therapeutics for NF1-related tumors using isogeneic pairs of NF1-proficient and deficient immortalized human Schwann cells. We utilized these in a large-scale high throughput screen (HTS) for drugs that preferentially kill NF1-deficient cells, through which we identified 23 compounds capable of killing NF1-deficient Schwann cells with selectivity. Multiple hits from this screen clustered into classes defined by method of action. Four clinically interesting drugs from these classes were tested in vivo using both a genetically engineered mouse model of high-grade peripheral nerve sheath tumors and human MPNST xenografts. All drugs tested showed single agent efficacy in these models as well as significant synergy when used in combination with the MEK inhibitor selumetinib. This HTS platform yielded novel therapeutically relevant compounds for the treatment of NF1-associated tumors and can serve as a tool to rapidly evaluate new compounds and combinations in the future.

Laser Interstitial Thermal Therapy as a Treatment Option for Malignant Peripheral Nerve Sheath Tumor Metastases to the Brain: A Case Report

We present the unique case of a 60-year-old female with neurofibromatosis type 1 (NF1) who underwent laser interstitial thermal therapy (LITT) for metastatic malignant peripheral nerve sheath tumor (MPNST) of the brain. She presented to the emergency room complaining of one week of dysarthria and facial droop. An MRI of the brain demonstrated a homogeneously enhancing left frontal mass; although rare, given her history of pulmonary MPNST, brain invasion was considered likely. No generally accepted guidelines for the treatment of MPNST with cerebral metastases exist; however, LITT was chosen due to tumor morphology and proximity to eloquent brain structures. She did not experience any new or worsening neurological deficits post-operatively. Post-ablation MRI showed white matter edema surrounding the lesion, which is consistent with previously reported cases. This case illustrates the use of LITT for cytoreduction for rare brain metastases located near eloquent brain structures.

Malignant peripheral nerve sheath tumor of the uterine cervix: A case report and literature review

Malignant peripheral nerve sheath tumors (MPNSTs) are rare high-grade sarcomas arising from the peripheral nerves or peripheral nerve sheath cells. MPNSTs rarely occur in the soft tissue, especially in the uterine cervix. Few cases of cervical MPNST have been reported in the literature. The present study reports the case of a 36-year-old female patient who presented with vaginal bleeding. A cervical mass was detected by vaginal ultrasonography and the patient was diagnosed with MPNST via assessment of the morphological and immunohistochemical features of the tumor after surgery. The patient received chemotherapy and radiotherapy following surgery, and at 8 months post-treatment, had no recurrence or metastasis. Furthermore, the present study summarizes the characteristics of all reported cases of cervical MPNST and their potential differential diagnosis with other spindle cell tumors.

Epithelioid malignant peripheral nerve sheath tumor of the bladder and concomitant urothelial carcinoma: A case report

BACKGROUND

Epithelioid malignant peripheral nerve sheath tumor (EMPNST) of the bladder is a rare entity with devastating features. These tumors are thought to originate from malignant transformation of pre-existing schwannomas of pelvic autonomic nerve plexuses, and unlike the conventional malignant peripheral nerve sheath tumor (MPNST), are not associated with neurofibromatosis. The tumor has distinctive morphological, immunohistochemical and molecular features. Additionally, it tends to be more aggressive and have a higher mortality. This is the first case that presents with a synchronous urothelial carcinoma of the bladder and the epithelioid variant of MPNST in the literature. It's also the second reported case of EMPNST originating from the bladder wall.

CASE SUMMARY

In this case report, we present the detailed clinical course of a 71-year-old patient with EMPNST of the bladder alongside a literature review.

CONCLUSION

During the management of EMPNST cases, offering aggressive treatment modalities to the patient, such as radical cystectomy, is appropriate for the best chance to contain the disease, regardless of the tumor stage and the extent of local disease at initial diagnosis.

Low-Grade Malignant Peripheral Nerve Sheath Tumor: A Case Report of Exceptional Parapatellar Location in the Knee

Malignant tumors of the peripheral nerve sheaths are uncommon, constituting a small percentage, typically ranging from 2% to 5% of soft tissue sarcomas. Etiological diagnosis is often difficult but is guided by imaging and confirmed by histopathological and immunohistochemical examination. We report a case of a 46-year-old woman admitted for management of a mass in the medial parapatellar region of the right knee. Her medical history included a burn to the right leg five years ago and a previously undocumented resection of a medial parapatellar tissue mass in the right knee. Radiological examination showed a deep and superficial soft tissue mass in the medial soft tissue of the right knee opposite the patella, with no hemorrhagic components and heterogeneous enhancement after injection of gadolinium. Histopathology confirmed the diagnosis of a low-grade peripheral nerve sheath tumor, and a thoracic-abdominal-pelvic CT scan was performed, which was normal. Treatment consisted of a simple carcinological resection and local radiotherapy. No local recurrence was noted after one year of follow-up.

The role of radiotherapy in the management of malignant peripheral nerve sheath tumors: a single-center retrospective cohort study

PURPOSE

This study sought to investigate the role of radiotherapy (RT) in addition to surgery for oncological outcomes in patients with malignant peripheral nerve sheath tumors (MPNST).

METHODS

In this single-center, retrospective cohort study, histopathologically confirmed MPNST were analyzed. Local control (LC), overall survival (OS), and distant metastasis-free survival (DMFS) were assessed using the Kaplan-Meier estimator. Multivariable Cox regression analysis was performed to identify factors associated with LC, OS, and DMFS.

RESULTS

We included 57 patients with a median follow-up of 20.0 months. Most MPNSTs were located deeply (87.5%), were larger than 5 cm (55.8%), and had high-grade histology (78.7%). Seventeen patients received surgery only, and 25 patients received surgery and pre- or postoperative RT. Median LC, OS, and DMFS after surgery only were 8.7, 25.5, and 22.0 months; after surgery with RT, the median LC was not reached, while the median OS and DMFS were 111.5 and 69.9 months. Multivariable Cox regression of LC revealed a negative influence of patients presenting with local disease recurrence compared to patients presenting with an initial primary diagnosis of localized MPNST (hazard ratio: 8.86, p = 0.003).

CONCLUSIONS

The addition of RT to wide surgical excision appears to have a beneficial effect on LC. Local disease recurrence at presentation is an adverse prognostic factor for developing subsequent local recurrences. Future clinical and translational studies are warranted to identify molecular targets and find effective perioperative combination therapies with RT to improve patient outcomes.

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 the Nasal Cavity of a Neonate: A Case Report

Malignant peripheral nerve sheath tumor (MPNST) is a rare tumor that can develop on the lining of nerves and within the network of nerve fibers in different organs, and it is commonly found in the head and neck, limbs, and trunk. These tumors can occur in patients of any age. They most commonly occur in adults aged 20 to 50 years; however, fewer cases of this tumor in children have been reported. To date, no neonatal case of MPNST in the nasal cavity has been reported. Here, we report the case of a 4-day-old female newborn who presented with a nasal mass that re-enlarged after surgery and was diagnosed as MPNST of the nasal cavity on the basis of pathological results. This is the first report of MPNST in the nasal cavity of a neonate. Differential diagnosis and treatment of nasal masses have been proposed in the related literature.

The quest for effective immunotherapies against malignant peripheral nerve sheath tumors: Is there hope?

Immune-based therapies represent a new paradigm in the treatment of multiple cancers, where they have helped achieve durable and safe clinical responses in a growing subset of patients. While a wealth of information is available concerning the use of these agents in treating the more common malignancies, little has been reported about the use of immunotherapies against malignant peripheral nerve sheath tumors (MPNSTs), a rare form of soft tissue sarcoma that arises from the myelin sheaths that protect peripheral nerves. Surgical resection has been the mainstay of therapy in MPNSTs, but the recurrence rate is as high as 65%, and chemotherapy is generally ineffective. The immune contexture of MPNSTs, replete with macrophages and a varying degree of T cell infiltration, presents multiple opportunities to design meaningful therapeutic interventions. While preliminary results with macrophage-targeting strategies and oncolytic viruses are promising, identifying the subset of patients that respond to immune-based strategies will be a milestone. As part of our effort to help advance the use of immunotherapy for MPNSTs, here we describe recent insights regarding the immune contexture of MPNSTs, discuss emerging immune-based strategies, and provide a brief overview of potential biomarkers of response.

Chemotherapeutic drugs for soft tissue sarcomas: a review

Despite the low incidence of soft tissue sarcomas (STSs), hundreds of thousands of new STS cases are diagnosed annually worldwide, and approximately half of them eventually progress to advanced stages. Currently, chemotherapy is the first-line treatment for advanced STSs. There are difficulties in selecting appropriate drugs for multiline chemotherapy, or for combination treatment of different STS histological subtypes. In this study, we first comprehensively reviewed the efficacy of various chemotherapeutic drugs in the treatment of STSs, and then described the current status of sensitive drugs for different STS subtypes. anthracyclines are the most important systemic treatment for advanced STSs. Ifosfamide, trabectedin, gemcitabine, taxanes, dacarbazine, and eribulin exhibit certain activities in STSs. Vinca alkaloid agents (vindesine, vinblastine, vinorelbine, vincristine) have important therapeutic effects in specific STS subtypes, such as rhabdomyosarcoma and Ewing sarcoma family tumors, whereas their activity in other subtypes is weak. Other chemotherapeutic drugs (methotrexate, cisplatin, etoposide, pemetrexed) have weak efficacy in STSs and are rarely used. It is necessary to select specific second- or above-line chemotherapeutic drugs depending on the histological subtype. This review aims to provide a reference for the selection of chemotherapeutic drugs for multi-line therapy for patients with advanced STSs who have an increasingly long survival.

Multifocal malignant peripheral nerve sheath tumor in patients with neurofibromatosis type I: Report of two cases and review of literature

BACKGROUND

Malignant peripheral nerve sheath tumors (MPNSTs) are one of the rarest soft-tissue sarcomas with a prevalence of 0.001% in the general population. It is closely associated with a unique neurocutaneous stigmata under the spectrum of the dermatological manifestations of neurofibromatosis type 1 (NF1). Almost 81% of MPNST arises from a precursor neuroma, and multifocality of these lesions is extremely rare, making up to 0.001% of cases. Moreover, spinal cases are extremely uncommon with only four cases reported internationally. Here, we present the fifth and sixth spinal MPNST cases with a brief review of literature.

CASE DESCRIPTION

We describe two unusual cases of multifocal MPNST in relation to NF1 occurring in the spinal cord. Both patients presented with local pain and myelopathic symptoms. The two patients underwent wide surgical resection, followed by neoadjuvant radiotherapy and reported immediate postoperative improvement of the presented complaint; however, one patient suffered from rapid recurrence and metastasis.

CONCLUSION

Due to the scarcity of spinal cases related to MPNST, no clear guidelines regarding the management of these cases are set in the literature. Histopathological diagnosis remains as the most pivotal diagnostic tool as they can mimic other peripheral nerve sheath lesions, such as neuromas and schwannomas, in imaging. Cases that were managed by early surgical intervention in addition to neoadjuvant radiotherapy reported the best outcome. However, cases of MPNST in concomitance with NF1 were found to be resistant to both chemo and radiotherapy and have high recurrence rate.

Primary Cardiac Schwannoma: A Meta-Analysis of Individual Case Reports

Primary cardiac schwannoma (PCS) is a neurogenic tumor that arises from Schwann cells. Malignant schwannoma (MSh) is an aggressive cancer comprising 2% of all sarcomas. Information on the proper management of these tumors is limited. Four databases were searched for case reports/series of PCS. The primary outcome was overall survival (OS). Secondary outcomes included therapeutic strategies and the corresponding outcomes. Among 439 potentially eligible studies, 53 met the inclusion criteria. The patients included had 43.72 ± 17.76 years and 28.3% were males. Over 50% of patients had MSh, with 9.4% also demonstrating metastases. Schwannoma commonly occurs in the atria (66.0%). Left-sided PCS were more common than right-sided ones. Surgery was performed in almost 90% of the cases; chemotherapy and radiotherapy were used in 16.9% and 15.1% of cases, respectively. Compared to benign cases, MSh occurs at a younger age and is commonly located on the left side. OS of the entire cohort at 1 and 3 years were 60.7%, and 54.0%, respectively. Females and males OS were similar up to 2 years follow-up. Surgery was associated with higher OS (p < 0.01). Surgery is the primary treatment option for both benign and malignant cases and was the only factor associated with a relative improvement in survival.

Patient demographics, tumor characteristics, and outcomes following surgical treatment of benign and malignant brachial plexus tumors: a systematic review

BACKGROUND

Various treatment options have been introduced for the management of primary tumors of the brachial plexus (BP), ranging from conservative therapy to wide local excision with/without postoperative chemoradiotherapy. However, no consensus exists regarding optimal treatment strategies based on collated and published data.

OBJECTIVE

The aim of this study was to investigate the clinicopathological characteristics and outcome of patients with primary tumors of the BP who underwent surgical treatment.

DATA SOURCES

A systematic search of the four main online databases, including Web of Science (WOS), PubMed, Scopus, and Google Scholar, was conducted.

STUDY SELECTION

All related articles addressing the clinical outcome and role of surgical interventions for management of primary tumors of the BP.

INTERVENTION

Optimal surgical and radiotherapeutic interventions for benign and malignant lesions based on the pathologic characteristics and location of primary BP tumors.

RESULTS

A total of 687 patients (693 tumors) with a mean age of 41.7±8.7 years old were evaluated. In total, 629 (90.8%) tumors were benign, and 64 (9.2%) were malignant, with a mean tumor size of 5.4±3.1 cm. The location of the tumor was reported for 639 patients. For these tumors, 444 (69.5%) originated from the supraclavicular region, and 195 (30.5%) were infraclavicular. The trunks were the most common location for tumor involvement, followed by the roots, cords, and terminal branches. Gross total resection was achieved in 432 patients and subtotal resection (STR) was performed in 109 patients. With neurofibromas, STR still resulted in good outcomes. The outcomes following treatment of malignant peripheral nerve sheath tumors were poor regardless of the type of resection. In general, symptoms related to pain and sensory issues resolved rapidly postoperatively. However, the resolution of motor deficits was often incomplete. Local tumor recurrence occurred in 15 (2.2%), patients and distant metastasis was observed in only eight (1.2%) cases. The overall mortality was 21 (3.1%) patients among the study population.

LIMITATIONS

The main limitation was the lack of level I and II evidence.

CONCLUSIONS

The ideal management strategy for primary BP tumors is complete surgical resection. However, in some cases, particularly for neurofibromas, STR may be preferable to preserve maximal neurological function. The degree of surgical excision (total or subtotal) mainly depends on the pathological characteristics and primary location of the tumor.

Primary Malignant Peripheral Nerve Sheath Tumor of the Stomach: A Rare Case Report and Review of Literature

Malignant peripheral nerve sheath tumor (MPNST) is a spindle cell sarcoma originating from peripheral nerves or showing differentiation of nerve sheath components. Primary MPNST of the stomach is an extremely rare neoplasm with only a few published reports in the literature. We present the case of a 58-year-old male patient with MPNST in the stomach. The patient was admitted due to upper abdomen discomfort. Gastroscopy revealed a huge ulcer lesion in the stomach, and biopsy revealed a spindle cell malignant neoplasm. No other specific findings were found in the whole-body imaging examination. Subtotal gastrectomy was performed. Histologically, an ulcer-type, push-infiltrating mass composed of dense, woven-like spindle cells with frequent mitosis could be seen. In immunohistochemistry, the tumor cells were negative for expression of H3K27 trimethylation (H3K27me3), keratin (AE1/AE3), epithelial membrane antigen (EMA), CD34, KIT, DOG1 (ANO1), S-100, SOX10, smooth muscle actin, desmin, myogenin, MDM2, CDK4, P16 (CDKN2A) and SS18-SSX (SS18::SSX). Primary MPNST of the stomach was diagnosed based on histological and immunohistochemical results. During the 2.5 years follow-up period after surgery, no recurrence was observed.

Malignant Peripheral Nerve Sheath Tumors: Latest Concepts in Disease Pathogenesis and Clinical Management

Malignant peripheral nerve sheath tumor (MPNST) is an aggressive soft tissue sarcoma with limited therapeutic options and a poor prognosis. Although neurofibromatosis type 1 (NF1) and radiation exposure have been identified as risk factors for MPNST, the genetic and molecular mechanisms underlying MPNST pathogenesis have only lately been roughly elucidated. Plexiform neurofibroma (PN) and atypical neurofibromatous neoplasm of unknown biological potential (ANNUBP) are novel concepts of MPNST precancerous lesions, which revealed sequential mutations in MPNST development. This review summarized the current understanding of MPNST and the latest consensus from its diagnosis to treatment, with highlights on molecular biomarkers and targeted therapies. Additionally, we discussed the current challenges and prospects for MPNST management.

Experience of a single center in the treatment of rare malignant peripheral nerve sheath tumors during the years 1991-2021

Malignant peripheral nerve sheath tumor (MPNST) is a rare sarcoma with a poor prognosis, as the aggressive types of this cancer tend to grow rapidly and metastasize frequently. MPNST is associated with neurofibromatosis type 1 gene mutation. The minority of cases arise secondary to radiation therapy or sporadically. The primary treatment for MPNST is early surgical resection of the tumor. The aim of this study was to retrospectively evaluate the outcome of the treatment of MPNST in Helsinki University Hospital from the years 1991 to 2021. Fourteen MPNST cases were evaluated in this study retrospectively. Descriptive statistical analysis was performed on the collected patient data. Marginal resection was completed in nine cases, wide margins were achieved in three cases, and in two cases the final histological examination of the specimen revealed intralesional removal. During the follow-up time of 36.7 ± 12.1 months, all patients who underwent wide margin resection were alive. One patient died 22 months after intralesional resection and six within 38.3 ± 30.9 months of marginal resection. Seventy-one percent of tumor surgeries resulted in Clavien-Dindo class 3b complications, reflecting the complexity of the surgeries. The aggressive nature of MPNST and the large size of these tumors requires extensive surgery, which can lead to complications. The prognosis of MPNST needs improvement.

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.

Analysis of treatment sequence and outcomes in patients with relapsed malignant peripheral nerve sheath tumors

Background

Malignant peripheral nerve sheath tumors (MPNST) are aggressive soft tissue sarcomas originating from cellular components within the nerve sheath. The incidence of MPNST is highest in people with neurofibromatosis type 1 (NF1), and MPNST is the leading cause of death for these individuals. Complete surgical resection is the only curative therapeutic option, but is often unfeasible due to tumor location, size, or presence of metastases. Evidence-based choices of chemotherapy for recurrent/refractory MPNST remain elusive. To address this gap, we conducted a retrospective analysis of our institutional experience in treating patients with relapsed MPNST in order to describe patient outcomes related to salvage regimens.

Methods

We conducted a retrospective electronic health record analysis of patients with MPNST who were treated at Johns Hopkins Hospital from January 2010 to June 2021. We calculated time to progression (TTP) based on salvage chemotherapy regimens.

Results

Sixty-five patients were included in the analysis. Upfront therapy included single or combined modalities of surgery, chemotherapy, or radiotherapy. Forty-eight patients received at least 1 line of chemotherapy, which included 23 different regimens (excluding active clinical studies). Most patients (n = 42, 87.5%) received a combination of doxorubicin, ifosfamide, or etoposide as first-line chemotherapy. Salvage chemotherapy regimens and their TTP varied greatly, with irinotecan/temozolomide-based regimens having the longest average TTP (255.5 days, among 4 patients).

Conclusions

Patients with advanced or metastatic MPNST often succumb to their disease despite multiple lines of therapy. These data may be used as comparative information in decision-making for future patients and clinical trials.

Clinical Outcome After Pencil Beam Scanning Proton Therapy of Patients With Non-Metastatic Malignant and Benign Peripheral Nerve Sheath Tumors

Objective

Peripheral nerve sheath tumors (PNSTs) commonly arise from peripheral nerve roots and grow locally invasive. Malignant PNSTs (mPNSTs) represent aggressive sarcomas of neural origin that can originate from PNSTs. Radiation therapy is commonly used as part of the required multimodal treatment. However, both entities tend to occur early in life and are associated with the genetic disorder neurofibromatosis type 1 (NF-1), which is known to cause increased radiosensitivity. Pencil beam scanning proton therapy (PBSPT) allows for a minimization of the dose delivered to organs at risk and the integral dose and, thus, potentially also a reduction of radiation-induced adverse events. We report the clinical outcome and toxicity rates of patients with (m)PNSTs treated with PBSPT.

Methods

We retrospectively reviewed 36 patients who received PBSPT (median dose, 64 GyRBE) with curative intent for (m)PNSTs between 1999 and 2020 at our institute. Twenty-eight (78%) and 8 (22%) patients were treated at diagnosis and for tumor recurrence/progression, respectively. The median age was 32 years (range, 3–75), and 25 (69%) patients were male. mPNST and PNST were diagnosed in 31 (86%) and 5 (14%) patients, respectively. Underlying NF-1 disease was found in 8 (22%) patients. Acute and late toxicities were recorded according to Common Terminology Criteria for Adverse Events, version 4.1 (CTCAE v4.1). Overall survival (OS), local control (LC), and distant control (DC) were estimated using the Kaplan–Meier method.

Results

With a median follow-up time of 31 months (range, 4–194), 13 (36%) patients died from a progressive disease, 8 (22%) experienced local failure, and 14 (39%) experienced distant failure after PBSPT. Estimated 2-year OS, LC, and DC were 75.5%, 73.5%, and 61.2%, respectively. Acute grade 3 toxicity (dermatitis, mucositis, and pain) was observed in 5 (14%) patients. Late grade 3 cataract and osteonecrosis were both observed in 1 (3%) patient at 34 and 194 months after PBSPT, respectively. There was no late grade &gt;3 toxicity or radiation-induced secondary cancer.

Conclusion

To our knowledge, this is the first study to analyze the outcome of (m)PNSTs treated with proton therapy using a PBS delivery paradigm. In our cohort, consisting mainly of patients with mPNSTs, we report reasonable oncological outcomes and low toxicity rates after PBSPT.

A rare case of cecal malignant peripheral nerve sheath tumor in a dog

A 12-year-old mixed-breed dog presented with a 2-month history of abdominal distension. Radiographic examination, abdominal ultrasonography, and computed tomography revealed a mass in the cecum (15.0 × 11.9 × 4.5 cm). The cecal mass was surgically removed and examined histopathologically. Immunohistochemically, the neoplastic cells expressed S-100 and neuron specific enolase but not α-smooth muscle actin and CD117 (c-kit). These histologic and immunohistochemical features indicated that the mass was consistent with a malignant peripheral nerve sheath tumor (MPNST). In dogs, most MPNSTs arise from the brachial plexus, spinal nerve root, and skin of the extremities. However, gastrointestinal MPNSTs in dogs have not been described previously. To the best of our knowledge, this is the first report to describe cecal MPNST in a dog.

Pembrolizumab Achieves a Complete Response in an NF-1 Mutated, PD-L1 Positive Malignant Peripheral Nerve Sheath Tumor: A Case Report and Review of the Benchmarks

Malignant peripheral nerve sheath tumors (MPNSTs) represent a rare subtype of neural crest cell-derived soft tissue sarcomas (STS). Standard of care therapy comprises surgical resection followed by adjuvant radiation, and most clinical studies have demonstrated finite survival benefit of radiation and chemotherapy. In metastatic disease, palliative chemotherapy provides very limited efficacy. We report a 60-year-old male patient with a primary para vertebral tumor at T7-T8 with lung metastases who recurred after surgical resection and later progressed on epirubicin plus ifosfamide. He was an international patient and referred to the phase 1 clinic. Molecular profiling and immunohistochemistry of the tumor revealed a PD-L1 expression of 70% (2+) and pathogenic genetic alterations by next-generation sequencing in ARID1A, CDKN2A, KMT2A, NF1, and TP53. Immune checkpoint therapy (ICT) with pembrolizumab was commenced, and interval computed tomography revealed a complete remission by cycle 6. Randomized clinical trials illustrate that ICTs such as anti-PD-1 and anti-CTLA4 monoclonal antibodies in STS cohorts display low or modest response rates by variable PD-L1 expression. This and 3 other case reports of disparate PD-L1 expression demonstrate complete responses in PD-L1 positive MPNSTs treated with ICT. These case reports necessitate further study of ICT in neural crest cell subtype of STS.

Current concepts of neurofibromatosis type 1: pathophysiology and treatment

Neurofibromatosis type 1 is the most common tumor predisposition syndrome inherited in an autosomal dominant (100% penetrance) fashion with a wide variety of expressivity. From the perspective of plastic surgery, the most significant clinical symptoms, including disfiguration, peripheral neurologic symptoms, and skeletal abnormalities, are caused by various tumors originating from the affected nerves. Surgical removal is the standard of care for these tumors. However, the outcome is frequently unsatisfactory, facilitating the search for additional therapeutic adjuvants. Current trials of molecularly targeted therapies are promising.

Malignant Peripheral Nerve Sheath Tumors-A Comprehensive Review of Pathophysiology, Diagnosis, and Multidisciplinary Management

Malignant peripheral nerve sheath tumors (MPNSTs) are aggressive soft tissue sarcomas (STS) with nerve sheath differentiation and a tendency to metastasize. Although occurring at an incidence of 0.001% in the general population, they are relatively common in individuals with neurofibromatosis type 1 (NF1), for whom the lifetime risk approaches 10%. The staging of MPNSTs is complicated and requires close multi-disciplinary collaboration. Their primary management is most often surgical in nature, with non-surgical modalities playing a supportive, necessary role, particularly in metastatic, invasive, or widespread disease. We, therefore, sought to provide a comprehensive review of the relevant literature describing the characteristics of these tumors, their pathophysiology and risk factors, their diagnosis, and their multi-disciplinary treatment. A close partnership between surgical and medical oncologists is therefore necessary. Advances in the molecular characterization of these tumors have also begun to allow the integration of targeted RAS/RAF/MEK/ERK pathway inhibitors into MPNST management.

Neurofibromin Deficiency Causes Epidermal Growth Factor Receptor Upregulation through the Activation of Ras/ERK/SP1 Signaling Pathway in Neurofibromatosis Type 1-Associated Malignant Peripheral Nerve Sheet Tumor

Neurofibromatosis type 1 (NF1) is an autosomal dominant human genetic disorder. The progression of benign plexiform neurofibromas to malignant peripheral nerve sheet tumors (MPNSTs) is a major cause of mortality in patients with NF1. Although elevated epidermal growth factor receptor (EGFR) expression plays a crucial role in the pathogenesis of MPNST, the cause of EGFR overexpression remains unclear. Here, we assessed EGFR expression levels in MPNST tissues of NF1 patients and NF1 patient-derived MPNST cells. We found that the expression of EGFR was upregulated in MPNST tissues and MPNST cells, while the expression of neurofibromin was significantly decreased. Manipulation of NF1 expression by NF1 siRNA treatment or NF1-GAP-related domain overexpression demonstrated that EGFR expression levels were closely and inversely correlated with neurofibromin levels. Notably, knockdown of the NF1 gene by siRNA treatment augmented the nuclear localization of phosphorylated SP1 (pSP1) and enhanced pSP1 binding to the EGFR gene promoter region. Our results suggest that neurofibromin deficiency in NF1-associated MPNSTs enhances the Ras/ERK/SP1 signaling pathway, which in turn may lead to the upregulation of EGFR expression. This study provides insight into the progression of benign tumors and novel therapeutic approaches for treatment of NF1-associated MPNSTs.

Clinical Outcomes and Prognostic Factors for Patients with Malignant Peripheral Nerve Sheath Tumour

Introduction

Few studies have described the characteristics and prognostic factors of patients with malignant peripheral nerve sheath tumour (MPNST). In this study, we retrospectively investigated the clinicopathological features, clinical outcomes, and prognostic factors of these patients. Patients and Methods. We recruited patients with MPNST who were treated at our institutions from 1991 to 2020. We collected and statistically analysed information on patient-, tumour-, and treatment-related factors. The median follow-up period was 61 months (range, 1-335.8 months).

Results

A total of 60 patients (31 males, 29 females) with a median age of 55 years (range, 8-84 years) at initial diagnosis were included. The median tumour size was 7 cm (range, 1.6-30 cm) in the greatest dimension. The 5-year overall survival (OS) rate of all patients was 69.5%. Univariate analysis revealed that large-sized tumour, metastasis at diagnosis, and no surgery of the primary tumour were significantly associated with patients with worse OS. Multivariate analysis identified surgery of the primary tumour as an independent prognostic factor for improved OS. Among patients with localised disease at diagnosis who underwent surgery of the primary tumour at our institutions, the 5-year OS, local recurrence-free survival (LRFS), and metastasis-free survival (MFS) rates were 81.1%, 78.2%, and 70.3%, respectively. Univariate analysis revealed that positive surgical margin was significantly correlated with unfavourable OS and LRFS, and high grade was a poor prognostic indicator for MFS.

Conclusion

Complete surgical resection with negative surgical margins is necessary for a successful MPNST treatment. Multidisciplinary management of MPNST with aggressive features is important for optimising patient outcomes.

Molecular targeted therapy for advanced or metastatic soft tissue sarcoma

Soft tissue sarcomas are a form of rare and heterogeneous neoplasms with high recurrence rate and mortality. Over the past decades, less progress has been achieved. Surgical management with or without adjuvant/neoadjuvant radiotherapy is still the first-line treatment for localized soft tissue sarcomas, and chemotherapy is the additional option for those with high-risk. However, not all patients with advanced or metastatic soft tissue sarcomas benefit from conventional chemotherapy, targeted therapy takes the most relevant role in the management of those resistant to or failed to conventional chemotherapy. Heterogeneous soft tissue sarcomas vary from biological behavior, genetic mutations, and clinical presentation with a low incidence, indicating the future direction of histotype-based even molecule-based personalized therapy. Furthermore, increasing preclinical studies were carried out to investigate the pathogenesis and potential therapeutic targets of soft tissue sarcomas and increasing new drugs have been developed in recent years, which had started opening new doors for clinical treatment for patients with advanced/metastatic soft tissue sarcomas. Here we sought to summarize the concise characteristics and advance in the targeted therapy for the most common subtypes of soft tissue sarcomas.

[Expert consensus on diagnosis and management of neurofibromatosis type 1 (2021 edition)]

Neurofibromatosis type 1 (NF1) is an autosomal dominant neoplastic disease caused by mutations in the NF1 gene and one of the most challenging diseases to treat. Patients have a characteristic phenotype with neurofibromas as the main features in different forms, including numerous cutaneous neurofibromas, plexiform neurofibromas involving the primary nerves, or malignant peripheral nerve sheath tumors with a very short survival period after malignant transformation. NF1 patients also suffer from multi-system involvement, with a high rate of deformity and disability, making complete surgical resection more difficult. Currently, there is no consensus on the diagnosis and treatment of NF1 in China, and different disciplines have different understandings of NF1. Multidisciplinary systematic evaluations and cooperative treatments are the keys to improve the treatment, quality of life, and prognosis of NF1 patients. In 2020, the Department of Plastic Surgery of the Ninth People's Hospital of Shanghai Jiaotong University School of Medicine led the establishment of the first multi-center collaboration group for NF1 in China. Furthermore, the group had worked with renowned experts from the various departments including surgical oncology, medical oncology, dermatology, reproductive medicine, et al. in China to formulate the "Expert consensus on diagnosis and management of neurofibromatosis type 1 (2021 edition)", aiming to promote standardized and homogeneous treatment covering the whole life cycle of NF1 patients and improve the treatment level and outcome of NF1 patients in China.

Cranial and Spinal Malignant Peripheral Nerve Sheath Tumor: A Pathological Enigma

Objective  Malignant peripheral nerve sheath tumor (MPNST) arises from nerve sheaths, mostly seen in peripheral nerves but rare in craniospinal nerves. The information available in the literature to build up treatment strategy and improve clinical outcomes is scarce. We are reviewing cases from our institute, with emphasis on radiological features for early differentiation from its benign variants.

Methods  We analyzed pathologically diagnosed cases retrospectively from January 2007 to December 2018 at our institute. Clinicoradiological details and treatment parameters were collected from medical records for evaluation. Each case was contacted telephonically for final clinical follow-up at the time of writing the manuscript.

Results  A total of seven cases of MPNST were diagnosed in the last 10 years. It included four intracranial and three spinal cases. The mean age for the cohort was 34.3 years, with five females. We could achieve gross total resection (GTR) and subtotal resection in four (57.1%) and two (28.6%) cases, respectively. We could achieve an overall survival of 57.1% in the average follow-up of 28.2 months (range: 8–84 months).

Conclusion  MPNST is a rare tumor with a bad prognosis. Radical surgical resection is the mainstay of the treatment, but it is not always possible to achieve it because of the inaccessible location and large size of lesions. Preoperative diagnosis is challenging; however, few radiological findings may give a clue toward it. As a disease entity overall, it has a poor outcome with a high rate of fatality.

Malignant Peripheral Nerve Sheath Tumor Presenting as Horner's Syndrome

Malignant peripheral nerve sheath tumor (MPNST) is a rare, aggressive sarcomatous tumor that arises from peripheral nerve sheath and shows Schwann cell differentiation. They are commonly seen among cases with existing benign plexiform neurofibromas, prior radiation treatment, and large germline mutations involving the entire neurofibromatosis 1 (NF1) gene. MPNST can have varied presentations; hence diagnosis remains a great challenge. Here we report a rare case of MPNST in an NF1 patient who presented with Horner´s syndrome. A young male reported swelling in the neck, dyspnea on exertion, and dysphagia. Subsequently, he was diagnosed to have a malignant peripheral nerve sheath tumor arising from the mediastinum and compressing the ipsilateral cervical sympathetic plexus causing Horner′s syndrome. The patient underwent surgical resection of the mediastinal mass followed by chemotherapy. His symptoms improved significantly following treatment. This case report emphasizes the fact that high suspicion of MPNST is required when NF1 cases present with mass lesions, so that early surgical clearance with chemoradiation may offer a near-complete cure.

A rare case report of malignant peripheral nerve sheath tumor involving both the small bowel and large bowel

Malignant peripheral nerve sheath tumor (MPNST) contains properties and histologic markers of both neural crest cells and mesenchymal cells. It is a rare diagnosis, with an incidence of 1:100,000/year or 4%–10% of soft-tissue sarcomas. There are very few cases reported and studied. Therefore, establishing a proper diagnosis and treatment of MPNST provides a challenge. We present this unique and rare case of metastatic MPNST of the small and large bowel with bone, pulmonary, liver, and splenic metastases. The patient subsequently developed hemorrhagic brain metastases and died 6 months after THE initial diagnosis.

Reconstruction of the chest wall after resection of malignant peripheral nerve sheath tumor: A case report

BACKGROUND

Malignant peripheral nerve sheath tumors (MPNSTs) are a group of rare and aggressive sarcomas that often arise from major peripheral nerves and represent a notable challenge to efficacious treatment. MPNSTs can occur in any body surface and visceral organs with nerve fiber distribution. The treatment options for MPNSTs include surgery, chemotherapy, and adjuvant radiotherapy.

CASE SUMMARY

A 26-year-old female cellist presented with chest pain on her left side when she squatted to lift the cello. One week later, a chest X-ray was performed and revealed fracture of the fourth rib on the left side. Three months later, the patient inadvertently touched a mass on the left side of the chest wall. Chest computed tomography (CT) three-dimensional reconstruction of the ribs revealed bone destruction of the fourth rib on the left side with a soft tissue mass shadow measuring 5.7 cm × 3.7 cm. CT-guided puncture biopsy of the tumor showed that heterotypic cells (spindle cells) tended to be nonepithelial tumor lesions. PET-CT demonstrated bone destruction and a soft tissue mass with avid 18F-fluorodeoxyglucose activity (SUV_max7.5) in the left fourth rib. The tumor of the left chest wall was resected under general anesthesia, and reconstruction of the chest wall was performed. The postoperative pathological report exhibited an MPNST.

CONCLUSION

MPNSTs are relatively chemo-insensitive tumors. The mainstay of treatment for MPNSTs remains resection with tumor-free margins.

Malignant Peripheral Nerve Sheath Tumor in an Army Reservist With Neurofibromatosis Type 1

Neurofibromatosis type 1 (NF1) is an autosomal dominant condition affecting 1 in 3,500 people resulting from an NF1 gene mutation that encodes the nonfunctional protein neurofibromin mutant. Neurofibromin is a negative regulator of RAS signaling involved in cell survival and proliferation. NF1 typically presents at birth or in early childhood with multiple light brown (café au lait) spots and axillary freckling. With age, patients may develop scattered neurofibromas as well as additional neurological and malignant abnormalities. Additionally, the nonfunctional protein neurofibromin mutant may be involved in the pathogenesis of peripheral malignant nerve sheath tumors, which is a rare and life-threatening complication of NF1. While a disqualifying condition for military duty, it may not initially be clinically apparent until complications develop. Here, we present a case of malignant peripheral sheath in an U.S. Army African American reservist with NF1 in whom cutaneous manifestations of NF1 such as café au lait spots and axillary freckling were not identified on the initial military entrance processing examination.

Systemic Options for Malignant Peripheral Nerve Sheath Tumors

OPINION STATEMENT

Malignant peripheral nerve sheath tumors (MPNSTs) are rare mesenchymal neoplasms that represent a profound therapeutic challenge due to their high proclivity for recurrence and metastasis and relatively poor response to systemic therapy regimens. While our understanding of the pathophysiology of MPNST is growing, including loss of the tumor suppressor gene neurofibromin and subsequent activation of the Ras pathway, targeted therapy to modify the poor prognosis seen in MPNST patients has thus far been without success. Correspondingly, MPNST patients are treated as per soft tissue sarcoma treatment algorithms with anthracycline-based therapy as the front-line therapy of choice for patients with unresectable, locally advanced, or metastatic MPNST. Beyond first-line anthracycline-based therapy, other standard cytotoxic chemotherapy agents used in advanced MPNST include the alkylating agent ifosfamide and the topoisomerase II inhibitor etoposide. Notably, soft tissue sarcoma regimens are used in MPNST despite distinct systemic therapy sensitivity and prognosis. This is particularly notable for neurofibromatosis type 1 (NF1)-associated MPNST, which is associated with poorer response to systemic therapy and prognosis than sporadic MPNST. As such, NF1-associated MPNST is a particular area in need of novel therapeutic strategies. Given the lack of benefit in the targeting of unique aspects of MPNST disease biology thus far, pre-clinical studies to identify novel rational therapies are critical to inform future clinical trials.

Selinexor, a First in Class, Nuclear Export Inhibitor for the Treatment of Advanced Malignant Peripheral Nerve Sheath Tumor

Malignant peripheral nerve sheath tumor (MPNST) is a highly malignant neoplasm arising from peripheral nerve or its attendant sheath and is derived from Schwann or pluripotent cells of neural crest origin. Patients with recurrent, unresectable, or advanced stage disease have limited treatment options, and current therapies are associated with little benefit. In this article, we report nine cases of MPNST treated with selinexor, an orally bioavailable, selective inhibitor of nuclear export, accompanied by tumor stabilization or regression.

Incidence and prognosis of distant metastasis in malignant peripheral nerve sheath tumors

BACKGROUND

Malignant peripheral nerve sheath tumors (MPNSTs) are a type of soft tissue sarcomas (STS) with recurrence and metastatic potential. We aimed to investigate the risk factors for developing distant metastases (DM) and to identify the prognostic factors in patients with DM.

METHODS

Based on the Surveillance, Epidemiology, and End Result (SEER) database, MPNST patients diagnosed between 2010 and 2016 were extracted in our study. The logistic regression model was performed for predicting DM development while the Cox proportional hazard regression model was conducted for revealing the prognostic factors.

RESULTS

Eventually, 764 patients diagnosed with MPNSTs were included with 109 cases presenting with metastases at initial diagnosis. Larger tumor size and lymph node metastases were independent risk factors for developing DM. The median overall survival (OS) for patients with metastases was 8.0 (95% CI: 6.1-9.9) months. Multiple metastatic sites and no surgical treatment were prognostic factors for worse survival. Tumors located in non-head and neck region were related with better survival.

CONCLUSIONS

The incidence of DM was 14.3% with a dismal median OS of 8.0 months for metastatic MPNSTs. More evaluation should be applied for patients with large tumor size and lymph metastases. Tumors located in head and neck region and the presence of multiple metastases predicted worse survival outcome. Surgical treatment can significantly improve the survival of MPNST patients with distant metastasis.

Transforming approaches to treating TRK fusion cancer: historical comparison of larotrectinib and histology-specific therapies

OBJECTIVE

The results from basket trials utilized to gain regulatory approval of tumor-agnostic therapies can be difficult to interpret without the context of a comparator arm. We describe the role and efficacy of histology-based treatments to provide a historical comparison with larotrectinib.

METHODS

A systematic literature review (SLR) was conducted on the clinical outcomes of current histology-based standard of care treatments used in non-small cell lung cancer, colorectal cancer, thyroid cancer, gliomas, soft tissue sarcoma, salivary gland cancer, and infantile fibrosarcoma (7 of the 21 tumor histologies in the larotrectinib trials). The review focused on advanced stage/metastatic disease to make a historical comparison with larotrectinib.

RESULTS

Larotrectinib provides positive outcomes in both adult and pediatric patients with advanced or metastatic solid tumors known to harbor NTRK gene fusions across a wide range of tumor types. Although the numbers of patients per tumor type are limited, the results of this historical comparison demonstrated that larotrectinib is an efficacious treatment option when naïvely indirectly compared with historical treatments across all 7 reviewed tumor types, especially in comparison to later lines of therapy.

CONCLUSIONS

Utilizing larotrectinib as a case example across these types of historical comparisons shows that larotrectinib provides positive efficacy outcomes in TRK fusion cancer across tumor histologies known to harbor NTRK gene fusions that may be preferable to historical treatments.

Protein Tyrosine Phosphatase Receptor S Acts as a Metastatic Suppressor in Malignant Peripheral Nerve Sheath Tumor via Profilin 1-Induced Epithelial-Mesenchymal Transition

Malignant peripheral nerve sheath tumors (MPNST) are aggressive sarcomas with over half of cases developed in the context of neurofibromatosis type 1. Surgical resection is the only effective therapy for MPNST. The prognosis is very dismal once recurrence or metastasis occurs. Epithelial-mesenchymal transition (EMT) is a key process of recurrence and metastasis involving reorganizations of the actin cytoskeleton and actin-binding proteins (ABP) play a non-negligible role. Protein tyrosine phosphatase receptor S (PTPRS), a tumor suppressor previously reported in colorectal cancer, hepatocellular carcinoma and head and neck cancer, is thought to mediate cell migration and invasion by downregulation of EMT. However, its role in MPNST remains unknown. In the present study, by using tissue microarray we demonstrated low expression of PTPRS was related to poor prognosis in MPNST. Knockdown of PTPRS in MPNST cell lines increased migration/invasion and EMT processes were induced with increased N-cadherin and decreased E-cadherin, which indicated PTPRS may serve as a tumor suppressor in MPNST. In addition, we tested all EMT related ABP and found profilin 1 was significantly elevated in PTPRS downregulated MPNST cell lines. As a member of actin-binding proteins, profilins are regulators of actin polymerization and contribute to cell motility and invasion, which have been reported to be responsible for EMT. Moreover, results showed that downregulation of profilin 1 could restore the EMT processes caused by PTPRS downregulation in vitro and in vivo. Furthermore, high expression of profilin 1 was significantly associated with dismal prognosis. These results highlighted PTPRS served as a potential tumor suppressor in the recurrence and metastasis of MPNST via profilin 1 induced EMT processes and it might provide potential targets for future clinical therapeutics.

Haematopoietic stem cell transplantation in adult soft-tissue sarcoma: an analysis from the European Society for Blood and Marrow Transplantation

BACKGROUND

The role of high-dose chemotherapy with autologous stem cell transplantation (ASCT) in the treatment of soft-tissue sarcoma (STS) remains an unsettled issue. Prospective clinical trials failed to prove a benefit of the procedure but were limited by small and heterogeneous patient cohorts. Thus, it is unknown if ASCT may be a valuable treatment option in specific patient subgroups.

METHODS

The purpose of this study was to investigate the value of ASCT according to histological subtype in STS patients who were registered in the European Society for Blood and Marrow Transplantation database between 1996 and 2016.

RESULTS

Median progression-free (PFS) and overall survival (OS) in the entire cohort of 338 patients were 8.3 and 19.8 months, respectively, and PFS and OS at 5 years were 13% and 25%, respectively. Analysis of outcomes in different subgroups showed that younger age, better remission status before transplantation and melphalan-based preparative regimen were predictive of benefit from ASCT, whereas histology and grading had no statistically significant impact.

CONCLUSIONS

Outcomes after ASCT compared favorably to those of recent trials on conventional chemotherapies and targeted therapies in STS, including histology-tailored approaches. ASCT, thus, should be reinvestigated in clinical trials focusing on defined patient subgroups.

Systemic Treatment for Advanced and Metastatic Malignant Peripheral Nerve Sheath Tumors-A Sarcoma Reference Center Experience

Malignant peripheral nerve sheath tumor (MPNST) is a rare type of soft tissue sarcomas. The localized disease is usually treated with surgery along with perioperative chemo- or radiotherapy. However, up to 70% of patients can develop distant metastases. The study aimed to evaluate the modes and outcomes of systemic treatment of patients with diagnosed MPNST treated in a reference center. In total, 115 patients (56 female and 59 male) diagnosed with MPNST and treated due to unresectable or metastatic disease during 2000–2019 were included in the retrospective analysis. Schemes of systemic therapy and the outcomes—progression-free survival (PFS) and overall survival (OS)—were evaluated. The median PFS in the first line was 3.9 months (95% CI 2.5–5.4). Doxorubicin-based regimens were the most commonly used in the first line (50.4% of patients). There were no significant differences in PFS between chemotherapy regimens most commonly used in the first line (p = 0.111). The median OS was 15.0 months (95% CI 11.0–19.0) and the one-year OS rate was 63%. MPNST are resistant to the majority of systemic therapies, resulting in poor survival in advanced settings. Chemotherapy with doxorubicin and ifosfamide is associated with the best response and longest PFS. Future studies and the development of novel treatment options are necessary for the improvement of treatment outcomes.

Malignant peripheral nerve sheath tumors - Outcomes and prognostic factors based on the reference center experience

INTRODUCTION

Malignant peripheral nerve sheath tumor (MPNST) accounts for about 5% of soft tissue sarcomas. It can occur as sporadic diseases or can be associated with type 1 neurofibromatosis. MPNST is usually associated with poor prognosis, mostly due to their aggressive behavior, high metastatic potential, and resistance to chemotherapy. Our study aimed to determine treatment outcomes and associated prognostic factors in a large cohort of patients with MPNSTs treated at the reference sarcoma center.

METHODS

239 consecutive patients (114 women and 125 men) diagnosed with MPNST between March 1998 and March 2018 who were treated with surgery with curative intent in the reference sarcoma center were included in the retrospective analysis.

RESULTS

The mean age at diagnosis was 51 years (range 15-86). 28 (11.7%) patients had neurofibromatosis type 1 associated tumors (NF1 positive). Median OS was 126.5 months and 5-year survival rate was 61.9% in the group treated with curative intent. Median DFS, LRFS and DMFS were 91.6, 126.5 and 126.5 months, respectively. We identified tumor size, high tumor grade and positive surgical margins as independent negative predictors of DFS, LRFS, DMFS and OS.

CONCLUSIONS

High-quality surgery remains a gold standard of MPNST treatment. High grade, size and quality of surgery are significant independent prognostic factors for overall survival. There is an unmet need for improvement, especially regarding the perioperative treatment and treatment of metastatic disease. Future studies on the biology of MPNST would lead to the development of novel treatment options and improvement of treatment outcomes.

Phase II clinical trial of pazopanib for patients with unresectable or metastatic malignant peripheral nerve sheath tumors

Malignant peripheral nerve sheath tumor (MPNST) often does not respond well to chemotherapy and develops against a background of NF1. The purpose of our study was to examine the efficacy of pazopanib against MPNST. Our study was designed as a physician-initiated phase II clinical trial in patients with advanced MPNST. Patients were registered from 11 large hospitals. The primary endpoint was set to clarify the clinical benefit rate (CBR) at 12 weeks according to response evaluation criteria in solid tumors (RECIST). Progression-free survival (PFS), overall survival (OS) and the CBR based on modified Choi evaluation at week 12 were set as secondary endpoints along with treatment-related safety. The study enrolled 12 patients. Median age was 49 years. Seven had Grade 2 and five Grade 3 according to the FNCLCC evaluation. Median follow-up period was 10.6 months. CBR at 12 weeks was both 50.0% (RECIST and Choi). The median PFS was 5.4 months for both RECIST and Choi, and the median OS was 10.6 months. Of special interest, the median PFS was 2.9 months for patients with FNCLCC Grade 2 and 10.2 months for Grade 3 (both RECIST and Choi). Grade 4 adverse events of neutropenia and lipase elevation were noted in one patient each. The results of this pazopanib therapy were generally better than those of any of the other single molecular targeted therapies reported previously. Although accumulation of more cases remains necessary, we conclude pazopanib treatment for MPNST to be a safe and promising treatment after doxorubicin-based chemotherapy.

Functional Restoration Following Resection of Malignant Peripheral Nerve Sheath Tumour of the Median Nerve: A Case Report

Management of malignant peripheral nerve sheath tumours (MPNSTs) is primarily surgical, involving surgical resection with wide margins, and frequently radiation therapy. When a MPNST involves a major peripheral nerve, wide resection leads to significant distal neurologic deficits. A patient who underwent resection of a MPNST involving the median nerve above the elbow is presented. Staged tendon and nerve transfers were performed to restore sensation to the thumb and index finger, thumb opposition and flexion, finger flexion and forearm pronation. These included: 1. radial sensory nerve branches to digital nerves of thumb and index finger, 2. ulnar nerve branch of flexor carpi ulnaris to pronator teres, 3. brachioradialis to flexor pollicis longus, 4. side-to-side transfer of flexor digitorum profundus tendon of index finger to middle, ring and little fingers, 5. extensor indicis proprius to abductor pollicis brevis. The rationale, approach, and favourable results of functional reconstruction in this patient are detailed.

Fungating malignant peripheral nerve sheath tumor arising from a slow-growing mass in the forearm: a case report and review of the literature

Background

Malignant peripheral nerve sheath tumor is a rare and aggressive form of sarcoma that arises from a peripheral nerve, mostly in association with neurofibromatosis type 1. Half of the cases were reported in the extremities, with the lungs being the most common site of metastasis. We report a rare case of successful limb salvage surgery performed for a large exophytic malignant peripheral nerve sheath tumor of the right forearm with wide surgical margins followed by split-thickness skin graft and later a flexor carpi radialis tendon transfer to extensor digitorum communis tendon.

Case presentation

A 51-year-old Bedouin Arabic man presented to our institution with an incompletely excised, large, fungating, malignant peripheral nerve sheath tumor occupying most of his right forearm. Staging imaging showed multiple lung nodules. He underwent wide local excision followed by skin graft and tendon transfer as a palliative measure to preserve the function of his dominant limb. The operation was performed without any complications, and the patient had an excellent postoperative result. Afterward, he was started on multiple lines of chemotherapy that failed because of disease progression, and the patient died 7 months after the operation.

Conclusion

Clinicians must consider the possibility of soft tissue sarcoma even in a patient with a small, slow-growing, superficial mass. Furthermore, a wrong open biopsy or nononcological surgical procedure may lead to possible contamination and ultimately a more radical procedure than would have originally been necessary, where this can be prevented by an early referral to a highly specialized sarcoma center.

Elbow flexion reconstruction after arm-sparing excision for high-grade triton sarcoma: a case report

Background

Soft tissue sarcomas affecting the root of an upper extremity raise the question of limb amputation depending on their location, size, and malignancy. Malignant triton tumors are a rare subtype of neurofibrosarcomas that have been poorly reported in the literature. We report the case of a challenging reconstruction of the upper extremity using a pedicled latissimus dorsal flap.

Case presentation

A 25-year-old Occidental man was referred to our sarcoma unit for the management of a large, high-grade malignant peripheral nerve sheath tumor with no regional or distant extension and very fast progression. He was treated first by concomitant neoadjuvant radiotherapy and chemotherapy. Carcinologic excision was performed “en bloc” including the skin, the tumor, and the flexor muscles of our patient’s elbow. Coverage of the skin defect and elbow flexion restoration were achieved by using a homolateral pedicled musculocutaneous latissimus dorsi flap. Histological analysis showed an R0 resection. The reconstruction process recovered a complete bending of his elbow. He is still in remission at 26 months follow-up.

Conclusions

A malignant triton tumor is a rare, aggressive, and high-grade sarcoma. It was successfully treated and this case report describes an effective treatment modality. Reconstructive surgery, allowing large, complete tumor removal, is indispensable after neoadjuvant chemotherapy and radiotherapy.

Prognostic Significance of Histological Subtype in Soft Tissue Sarcoma With Distant Metastasis

BACKGROUND/AIM

Few studies have examined the prognostic significance of histological subtypes in patients with soft tissue sarcoma (STS) and distant metastasis, and we evaluated the relationship between the histological subtypes and clinical outcomes.

PATIENTS AND METHODS

This retrospective study evaluated the histological subtypes of 105 patients with STS and distant metastasis. The STS histological subtypes were compared based on the clinical information.

RESULTS

The Kaplan-Meier curves for overall survival revealed that myxoid liposarcoma had a significantly better prognosis compared to Malignant Peripheral Nerve Sheath Tumor (MPNST) (p=0.0221). In the multivariate logistic regression analyses, the independent predictors of a poor prognosis were: i) large size, ii) advanced stage, and iii) non-surgical treatment for metastasis (p<0.05). The presence or absence of lung metastasis was not significantly associated with prognosis (p=0.4452).

CONCLUSION

Myxoid liposarcoma had a better prognosis compared to MPNST in STS patients with distant metastasis. The surgical removal of distant metastatic lesions may improve the patient's prognosis.