Neoadjuvant Ifosfamide and Epirubicin in the Treatment of Malignant Peripheral Nerve Sheath Tumors

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.

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.

Management of Central and Peripheral Nervous System Tumors in Patients with Neurofibromatosis

Neurofibromatosis type I (NF1), neurofibromatosis type 2 (NF2), and schwannomatosis represent a diverse group of genetic tumor predisposition syndromes with a shared feature of tumors affecting the peripheral nerve sheaths. PURPOSE OF REVIEW: Many advancements have been made in understanding the biologic underpinnings of these conditions, and in 2016 the first drug was approved by the FDA to treat pediatric symptomatic unresectable plexiform neurofibromas. RECENT FINDINGS: Mek inhibitors have provided a much-needed therapeutic avenue for NF1 patients with unresectable plexiform neurofibromas (PN), both for reduction of tumor bulk and for improvement in symptoms. Selumetinib is the first FDA approved drug for PN, but is only approved for children. Some research suggests that alternative Mek inhibitors and other mixed tyrosine kinase inhibitors may have better efficacy in adults. Vascular endothelial growth factor (VEGF) inhibitor bevacizumab can prolong hearing and delay the need for surgery in NF2 patients with bilateral vestibular schwannomas. This article provides an update regarding considerations and approaches when treating the tumors associated with the neurofibromatoses (NF), including risk and prognosis metrics, clinical trial results, surgical techniques, and radiation therapy recommendations.

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.

Unusual Presentation of Malignant Peripheral Nerve Sheath Tumour of Mandible as a Colossal Tumour After Neoadjuvant Chemotherapy

The uniqueness of this case is the presentation of malignant peripheral nerve sheath tumors arising from the mandible as a colossal tumor of size of about 28 cm and weight of 1.5 kg after the first cycle of neoadjuvant chemotherapy. Role of neoadjuvant chemotherapy remains controversial and can be avoided if margin negative resection is feasible.

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.

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.

Cutaneous Findings in Neurofibromatosis Type 1

Neurofibromatosis type 1 (NF1) is a complex autosomal dominant disorder associated with germline mutations in the NF1 tumor suppressor gene. NF1 belongs to a class of congenital anomaly syndromes called RASopathies, a group of rare genetic conditions caused by mutations in the Ras/mitogen-activated protein kinase pathway. Generally, NF1 patients present with dermatologic manifestations. In this review the main features of café-au-lait macules, freckling, neurofibromas, juvenile xanthogranuloma, nevus anemicus and other cutaneous findings will be discussed.

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.

Role of 18F-FDG PET/computed tomography in prognostication and management of malignant peripheral nerve sheath tumors

AIM

Malignant peripheral nerve sheath tumors (MPNSTs) are rare tumors arising from a peripheral nerve or in extraneural soft tissue which shows high metastatic potential and poor prognosis. They can arise de-novo or through malignant transformation in neurofibromatosis (NF-1). The purpose of our study is to evaluate potential role of fluorodeoxyglucose (FDG) PET/computed tomography (CT) in prognostication and management of MPNSTs.

MATERIALS AND METHODS

We have performed a retrospective analysis in patients of MPNSTs who underwent F-FDG PET/CT imaging for staging and restaging. Standardized uptake values (SUVmax and SUVmean) and texture parameters (calculated using radiomics package version 0.1.3) were measured for primary/recurrent lesions and were compared between two groups based on presence of event (recurrence/progression). Student t-test was applied for comparative analyses using the SPSS software package (version 23.0; IBM), with a significance level of 0.05.

RESULTS

Thirty patients (17 male, 13 female; mean age 42.7 ± 15.66 years) were included, who underwent F-FDG PET/CT for staging (n = 10) and restaging (n = 20). Change in management was observed in four patients at baseline and in three patients in follow-up imaging for response assessment, who had progressive disease which prompted treatment intensification. SUVmax of primary/recurrent lesion showed correlation with histopathologic grade (r = 0.712, P = 0.034). Textural analysis showed more heterogeneity in lesions in the high-risk group with recurrence and progression.

CONCLUSION

F-FDG PET/CT can be used for staging and restaging in MPNSTs leading to change in management. Texture analysis and quantitative F-FDG PET/CT parameters can help in prognostication at both baseline and relapse.

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.

Diagnosis and management of malignant peripheral nerve sheath tumors: Current practice and future perspectives

One of the most common malignancies affecting adults with the neurofibromatosis type 1 (NF1) cancer predisposition syndrome is the malignant peripheral nerve sheath tumor (MPNST), a highly aggressive sarcoma that typically develops from benign plexiform neurofibromas. Approximately 8-13% of individuals with NF1 will develop MPNST during young adulthood. There are few therapeutic options, and the vast majority of people with these cancers will die within 5 years of diagnosis. Despite efforts to understand the pathogenesis of these aggressive tumors, the overall prognosis remains dismal. This manuscript will review the current understanding of the cellular and molecular progression of MPNST, diagnostic workup of patients with these tumors, current treatment paradigms, and investigational treatment options. Additionally, we highlight novel areas of preclinical research, which may lead to future clinical trials. In summary, MPNST remains a diagnostic and therapeutic challenge, and future work is needed to develop novel and rational combinational therapy for these tumors.

Oncological Treatment Considerations Differ across Surgical Subspecialties Treating Malignant Peripheral Nerve Sheath Tumors: An International Survey

Background

Malignant peripheral nerve sheath tumors (MPNSTs) are rare and aggressive soft tissue sarcomas (STS) that, because of their origin, are operated by several surgical subspecialties. This may cause differences in oncologic treatment recommendations based on presentation. This study investigated these differences both within and between subspecialties.

Methods

A survey was distributed among several (inter)national surgical societies. Differences within and between subspecialties were analyzed by χ²-tests.

Results

In total, 30 surgical oncologists, 30 neurosurgeons, 85 plastic surgeons, and 29 “others” filled out the survey. Annual caseload, tumor sites operated, and fellowship training differed significantly between subspecialties. While most surgeons agreed upon preoperative use of MRI, the use of radiological staging and FDG-PET use differed between subspecialties. Surgical oncologists agreed upon core needle biopsies as an ideal type of biopsy while other subspecialties differed in opinion. On average, 53% of surgeons always consider preservation of function preoperatively, but 42% would never perform less extensive resections for function preservation. Respondents agreed that radiotherapy should be considered in tumor sizes >10 cm, microscopic, and macroscopic positive margins. A preferred sequence of radiotherapy administration differed between subspecialties. There was no consensus on indications and sequence of administration of chemotherapy in localized disease.

Conclusion

Surgical oncologists generally agree on preoperative diagnostics; other subspecialties do not. Considering the preservation of function differed among all subspecialties. Surgeons do agree on some indications for radiotherapy, yet the use of chemotherapy in localized MPNSTs lacks consensus. A preferred sequence of multimodal therapy differs between and within surgical subspecialties, but surgical oncologists prefer neoadjuvant radiotherapy.

Case Report: Metastasis of a Trigeminal Malignant Peripheral Nerve Sheath Tumor to the Corpus Callosum

BACKGROUND AND IMPORTANCE

Malignant peripheral nerve sheath tumors (MPNST) are relatively rare tumors of peripheral nerves that are notable for their locally aggressive nature, ability to metastasize, poor prognosis, and association with Neurofibromatosis type I. We present the case of a patient with a trigeminal nerve MPNST who developed an unusual metastasis to the corpus callosum, in the absence of any other central nervous system or systemic metastatic disease. We review the pathology and presentation of MPNST.

CLINICAL PRESENTATION

A 53-yr-old woman presented with a 1-yr history of paroxysmal facial pain and dysesthesias in the right V1 and V2 distributions of the trigeminal nerve. She was initially diagnosed with trigeminal neuralgia although further imaging showed a cavernous sinus mass extending along the trigeminal nerve. She later developed an isolated lesion in the corpus callosum that was biopsied and consistent with MPNST.

CONCLUSION

This case reviews the pathology and aggressive nature of MPNST and demonstrates an unusual site of metastasis. Clinicians should remain aware that MPNST can metastasize to sites in the central nervous system as well as systemically. Furthermore, clinicians should have a high index of suspicion for secondary causes of trigeminal neuralgia in cases with atypical features.