Diffuse Intrinsic Pontine Glioma in Children: Document or Treat?

A microRNA Prognostic Signature in Patients with Diffuse Intrinsic Pontine Gliomas through Non-Invasive Liquid Biopsy

Simple Summary

Diffuse intrinsic pontine glioma (DIPG) is a neuro-radiologically defined tumor of the brainstem, primarily affecting children, with most diagnoses occurring between 5 and 7 years of age. Surgical removal in DIPGs is not feasible. Subsequent tumor progression is almost universal and no biomarker for predicting the course of the disease has entered into clinical practice so far. Under these premises, it is essential to develop reliable biomarkers that are able to improve outcomes and stratify patients using non-invasive methods to determine tumor profiles. We designed a study assessing circulating miRNA expression by a high-throughput platform and divided patients into training and validation phases in order to disclose a potential signature with clinical impact. Our results for the first time have proved the usefulness of blood-circulating nucleic acids as powerful, easy-to-assay molecular markers of disease status in DIPG.

Abstract

Diffuse midline gliomas (DMGs) originate in the thalamus, brainstem, cerebellum and spine. This entity includes tumors that infiltrate the pons, called diffuse intrinsic pontine gliomas (DIPGs), with a rapid onset and devastating neurological symptoms. Since surgical removal in DIPGs is not feasible, the purpose of this study was to profile circulating miRNA expression in DIPG patients in an effort to identify a non-invasive prognostic signature with clinical impact. Using a high-throughput platform, miRNA expression was profiled in serum samples collected at the time of MRI diagnosis and prior to radiation and/or systemic therapy from 47 patients enrolled in clinical studies, combining nimotuzumab and vinorelbine with concomitant radiation. With progression-free survival as the primary endpoint, a semi-supervised learning approach was used to identify a signature that was also tested taking overall survival as the clinical endpoint. A signature comprising 13 circulating miRNAs was identified in the training set (n = 23) as being able to stratify patients by risk of disease progression (log-rank p = 0.00014; HR = 7.99, 95% CI 2.38–26.87). When challenged in a separate validation set (n = 24), it confirmed its ability to predict progression (log-rank p = 0.00026; HR = 5.51, 95% CI 2.03–14.9). The value of our signature was also confirmed when overall survival was considered (log-rank p = 0.0021, HR = 4.12, 95% CI 1.57–10.8). We have identified and validated a prognostic marker based on the expression of 13 circulating miRNAs that can shed light on a patient’s risk of progression. This is the first demonstration of the usefulness of nucleic acids circulating in the blood as powerful, easy-to-assay molecular markers of disease status in DIPG. This study provides Class II evidence that a signature based on 13 circulating miRNAs is associated with the risk of disease progression.

Effect of TWIST1 Gene on the Proliferation and Apoptosis of Human Glioma Cell Line TJ861 by Regulating Mammalian Target of Rapamycin Signaling Pathway

To observe TWIST1 gene expression in human glioma and study the effect human glioma cell line TJ861 on the proliferation and apoptosis, and further explore its potential mechanism to provide some reference for the targeted treatment of glioma in the future. Detection of cancer tissue (Carcinoma tissue) in 55 patients with glioma by RT-PCR and Expression level of TWIST1 in normal and paracancerous tissues (Adjacent tissue), the human glioma cell line TJ861 was further divided into, Nonsense sequence group, (si-NS group), TWIST1 Inhibition group (si-TWIST1 group) and control group. The glioma cells of si-NS group and si-TWIST1 group were transfected with nonsense sequence and TWIST1 siRNA respectively by liposome transfection technology. Use CCK8 assay to test the cell proliferation ability of each group at 0, 12, 24, 36, 48 and 72 hours; 48 hours after siRNA transfection, The ability of DNA replication in each group was detected by EdU staining; Apoptosis related protein expression, in each group, was analyzed by Western blot; TUNEL staining was used to test the apoptosis rate of each group; In the end, We studied TWIST1 effect knocking down on mTOR protein expression in human glioma cells and mTOR protein expression in cancer and adjacent tissues. TWIST1 expression in glioma cells was higher, compared with normal tissues (P <0.05); After transfection of TWIST1 siRNA into human glioma cell line TJ861 in vitro, CCK8 showed glioma cells proliferation ability in si-TWIST1 group at 12, 24, 36, 48 and 72 hours was lower, compared with the control group (P <0.05); After siRNA transfection at 48 hours, the DNA replication ability of glioma cells decreased significantly (P <0.05) with EdU staining; The inhibition of TWIST1 increased Bax expression in glioma cells, and inhibited Bcl-2 expression (P < 0.05) with Western blot; TUNEL staining further confirmed that the apoptosis level of glioma cells in the si-TWIST1 group was higher, compared with the control group (P <0.05). Finally, we found that mTOR protein expression in glioma was higher, compared with adjacent tissues. in vitro experiments showed that mTOR expression in glioma cells was decreased after the inhibition of TWIST1 (P <0.05). TWIST1 expression level in glioma was increased. The inhibition of TWIST1 inhibits the proliferation of glioma by blocking the mTOR signal pathway, and promote the apoptosis of glioma.

Reirradiation practices for children with diffuse intrinsic pontine glioma

Background

Diffuse intrinsic pontine gliomas (DIPGs) are a leading cause of brain tumor deaths in children. Current standard of care includes focal radiation therapy (RT). Despite clinical improvement in most patients, the effect is temporary and median survival is less than 1 year. The use and benefit of reirradiation have been reported in progressive DIPG, yet standardized approaches are lacking. We conducted a survey to assess reirradiation practices for DIPG in North America.

Methods

A 14-question REDCap survey was disseminated to 396 North American physicians who care for children with CNS tumors.

Results

The response rate was 35%. Participants included radiation-oncologists (63%; 85/135) and pediatric oncologists/neuro-oncologists (37%; 50/135). Most physicians (62%) treated 1 to 5 DIPG patients per year, with 10% treating more than 10 patients per year. Reirradiation was considered a treatment option by 88% of respondents. Progressive disease and worsening clinical status were the most common reasons to consider reirradiation. The majority (84%) surveyed considered reirradiation a minimum of 6 months following initial RT. Doses varied, with median total dose of 2400 cGy (range, 1200-6000 cGy) and fraction size of 200 cGy (range, 100-900 cGy). Concurrent use of systemic agents with reirradiation was considered in 46%, including targeted agents (37%), biologics (36%), or immunotherapy (25%). One-time reirradiation was the most common practice (71%).

Conclusion

Although the vast majority of physicians consider reirradiation as a treatment for DIPG, total doses and fractionation varied. Further clinical trials are needed to determine the optimal radiation dose and fractionation for reirradiation in children with progressive DIPG.

MRI-based diagnosis and treatment of pediatric brain tumors: is tissue sample always needed?

Traditional management of newly diagnosed pediatric brain tumors (PBTs) consists of cranial imaging, typically magnetic resonance imaging (MRI), and is frequently followed by tissue diagnosis, through either surgical biopsy or tumor resection. Therapy regimes are typically dependent on histological diagnosis. To date, many treatment regimens are based on molecular biology. The scope of this article is to discuss the role of diagnosis and further treatment of PBTs based solely on MRI features, in light of the latest treatment protocols. Typical MRI findings and indications for surgical biopsy of these lesions are described.

Pediatric intrinsic brainstem lesions: clinical, imaging, histological characterization, and predictors of survival

PURPOSE

Brainstem lesions comprise 10-20% of all pediatric brain tumors. Over the past years, the benefits of stereotactic biopsy versus the use alone of MRI features to guide treatment have been controversial.

METHODS

Retrospective study with pediatric patients submitted to stereotactic brainstem biopsies between 2008 and 2018. Demographic, clinical, imaging, and surgical characteristics were recorded, as well as the histological diagnosis, complications, and survival. Predictors of survival were evaluated through Cox regression models after multivariate adjustment.

RESULTS

Twenty-six patients (mean age of 8.8 ± 4.3 years and 14 female). Diagnosis was reached on 84.6% (95% CI 65.1-95.6%) of the patients. Glioma was diagnosed on 20 cases (11 high-grade and 9 low-grade lesions). There was no association between age and gender and the dichotomized histological diagnosis. Contrast enhancement, diffuse distribution, invasion of adjacent structures, and remote injury were present on 62.5%, 75.0%, 62.5%, and 25.0% of the cases. Hydrocephalus at admission was present on almost half of the patients (46.2%). Only radiological invasion of adjacent structures had a possible association with high-grade lesions (p = 0.057). Surgical trajectory was trans-cerebellar in most of the cases (79.9%). There were no major complications and only two minor/transitory complications. Poorer survival was independently associated with high-grade lesions (HR 32.14, 95% CI 1.40-735.98, p = 0.030) and contrast enhancement at MRI (HR 36.54, 95% CI 1.40-952.26, p = 0.031).

CONCLUSIONS

Stereotactic biopsy was safe and allows successful tissue sampling for a definite diagnosis. Poorer survival was independently associated with high-grade and contrast-enhancing lesions.

Liquid biopsy for diffuse intrinsic pontine glioma: an update

Diffuse intrinsic pontine glioma (DIPG), otherwise known as diffuse midline glioma with H3K27M mutation, is a devastating brainstem glioma without a cure. Efforts are currently underway to better optimize molecular diagnoses through biological sampling, which today remains largely limited to surgical biopsy sampling. Surgical intervention is not without its risks, and therefore a preference remains for a less invasive modality that can provide biological information about the tumor. There is emerging evidence to suggest that a liquid biopsy, targeting biofluids such as CSF and blood plasma, presents an attractive alternative for brain tumors in general. In this update, the authors provide a summary of the progress made to date regarding the use of liquid biopsy to diagnose and monitor DIPG, and they also propose future development and applications of this technique moving forward, given its unique histone biology.

Tumor dissemination through surgical tracts in diffuse intrinsic pontine glioma

OBJECTIVEDiffuse intrinsic pontine glioma (DIPG) is a highly aggressive and lethal brainstem tumor in children. In the 1980s, routine biopsy at presentation was abandoned since it was claimed "unnecessary" for diagnosis. In the last decade, however, several groups have reincorporated this procedure as standard of care or in the context of clinical trials. Expert neurosurgical teams report no mortality and acceptable morbidity, and no relevant complications have been previously described. The aim of this study was to review needle tract dissemination as a potential complication in DIPG.METHODSThe authors retrospectively analyzed the incidence of dissemination through surgical tracts in DIPG patients who underwent biopsy procedures at diagnosis in 3 dedicated centers. Clinical records and images as well as radiation dosimetry from diagnosis to relapse were reviewed.RESULTSFour patients (2 boys and 2 girls, age range 6-12 years) had surgical tract dissemination: in 3 cases in the needle tract and in 1 case in the Ommaya catheter tract. The median time from biopsy to identification of dissemination was 5 months (range 4-6 months). The median overall survival was 11 months (range 7-12 months). Disseminated lesions were in the marginal radiotherapy field (n = 2), out of the field (n = 1), and in the radiotherapy field (n = 1).CONCLUSIONSAlthough surgical tract dissemination in DIPG is a rare complication (associated with 2.4% of procedures in this study), it should be mentioned to patients and family when procedures involving a surgical tract are proposed. The inclusion of the needle tract in the radiotherapy field may have only limited benefit. Future studies are warranted to explore the benefit of larger radiotherapy fields in patients with DIPG.

DNX-2401, an Oncolytic Virus, for the Treatment of Newly Diagnosed Diffuse Intrinsic Pontine Gliomas: A Case Report

Diffuse intrinsic pontine gliomas (DIPGs) are aggressive glial brain tumors that primarily affect children, for which there is no curative treatment. Median overall survival is only one year. Currently, the scientific focus is on expanding the knowledge base of the molecular biology of DIPG, and identifying effective therapies. Oncolytic adenovirus DNX-2401 is a replication-competent, genetically modified virus capable of infecting and killing glioma cells, and stimulating an anti-tumor immune response. Clinical trials evaluating intratumoral DNX-2401 in adults with recurrent glioblastoma have demonstrated that the virus has a favorable safety profile and can prolong survival. Subsequently, these results have encouraged the transition of this biologically active therapy from adults into the pediatric population. To this aim, we have designed a clinical Phase I trial for newly diagnosed pediatric DIPG to investigate the feasibility, safety, and preliminary efficacy of delivering DNX-2401 into tumors within the pons following biopsy. This case report presents a pediatric patient enrolled in this ongoing Phase I trial for children and adolescents with newly diagnosed DIPG. The case involves an 8-year-old female patient with radiologically diagnosed DIPG who underwent stereotactic tumor biopsy immediately followed by intratumoral DNX-2401 in the same biopsy track. Because there were no safety concerns or new neurological deficits, the patient was discharged 3 days after the procedures. To our knowledge, this is the first report of intratumoral DNX-2401 for a patient with DIPG in a clinical trial. We plan to demonstrate that intratumoral delivery of an oncolytic virus following tumor biopsy for pediatric patients with DIPG is a novel and feasible approach and that DNX-2401 represents an innovative treatment for the disease.

Robot-Assisted Stereotactic Biopsy of Diffuse Intrinsic Pontine Glioma: A Single-Center Experience

BACKGROUND

Diffuse intrinsic pontine glioma (DIPG) is a childhood tumor with a dismal prognosis. Emerging molecular signatures have paved the way for stereotactic biopsy in selected centers. We present our experience in DIPG stereotactic needle biopsy using the Robotic Stereotactic-Assisted system (ROSA) in a series of consecutive pediatric patients.

METHODS

All stereotactic biopsy procedures for DIPG performed during the last year at our institution were considered. All procedures were carried out using the ROSA surgical assistant through a precoronary approach. All children underwent a postoperative computed tomography scan to document possible surgical complications and confirm the site of biopsy. Postoperative clinical changes were recorded to test morbidity of the procedure.

RESULTS

In the last year, we performed 7 pontine needle biopsies. Specimens were diagnostic and useful for molecular analysis in all cases. No surgical complications were observed. One child showed a transient neurologic worsening related to the biopsy that resolved within 2 weeks. The combination of the precoronary approach and use of the stereotactic ROSA system allowed single-session surgeries in all cases.

CONCLUSIONS

Pontine biopsy for DIPG is a safe procedure in selected centers. The advantages of the single-session procedure we described might be of particular interest in the pediatric setting.