Radiation therapy and concurrent topotecan followed by maintenance triple anti-angiogenic therapy with thalidomide, etoposide, and celecoxib for pediatric diffuse intrinsic pontine glioma

An Update on H3K27M-altered Diffuse Midline Glioma: Diagnostic and Therapeutic Challenges in Clinical Practice

H3K27-altered diffuse midline glioma (DMG H3K27-altered) is a relatively newly-designated WHO entity which primarily affects the midline structures of the central nervous system (CNS), including the brainstem (predominantly pontine region), thalamus, midbrain, or spinal cord, and primarily affects children and young adults. Despite the proximity of these tumors to eloquent areas in the CNS, novel stereotactic approaches have facilitated the ability to obtain tissue diagnoses without significant morbidity, providing molecular diagnostic information in more than half of patients. Conventionally fractionated radiation therapy to a total dose of 54-60 Gy in 27-30 fractions and 24 Gy in 12 fractions play a crucial role in the definitive treatment of these tumors in the primary and salvage settings, respectively. Hypofractionated regimens may allow for accelerated treatment courses in selected patients without jeopardizing disease control or survival. The decision to add concurrent or adjuvant systemic therapy mainly relies on the physicians' experience without solid evidence in the literature in favor of any particular regimen. Recently, novel agents, such as ONC201 have demonstrated promising oncologic outcomes in progressive/recurrent tumors and are currently under investigation in ongoing randomized trials. Given the scarcity of data and well-established guidelines due to the rare nature of the disease, we provide a contemporary overview on the molecular underpinnings of this disease entity, describe the role of radiotherapy and systemic therapy, and present practice management principles based on the published literature.

Metronomic Maintenance for High-Risk Pediatric Malignancies: One Size Will Not Fit All

Maintenance therapy sometimes relies on the use of metronomic chemotherapy (MC); that is, the continuous administration of low-dose chemotherapy. Maintenance therapy has been successfully used for decades in pediatric patients with acute lymphoblastic leukemia (ALL) and recent results have demonstrated improved outcomes in patients with pediatric high-risk rhabdomyosarcoma (RMS) on maintenance therapy. Here, we review the use of metronomic maintenance therapy in pediatric cancer and discuss its mechanisms of action on the tumor microenvironment and cancer cells. We also discuss its potential use as a chemotherapy alone or in combination with targeted therapies, immunotherapies, or agents for drug repurposing.

Identification of key genes and pathways associated with topotecan treatment using multiple bioinformatics tools

BACKGROUND

The goal of this study is to determine critical genes and pathways associated with topotecan using publicly accessible bioinformatics tools.

METHODS

Topotecan signatures were downloaded from the Library of Integrated Network-Based Cellular Signatures (LINCS) database (http://www.ilincs.org/ilincs/). Differentially expressed genes (DEGs) were defined as genes that appeared at least three times with p values <0.05 and a fold change of ≥50% (|log2FC| ≥ 0.58). Hub genes were identified by evaluating the following parameters using a protein-protein interaction network: node degrees, betweenness, and eigenfactor scores. Hub genes and the top-40 DEGs by |log2FC| were used to generate a Venn diagram, and key genes were identified. Functional and pathway enrichment analysis was performed using the Kyoto Encyclopedia of Genes and Genomes (KEGG) databases. Information on ovarian cancer patients derived from The Cancer Genome Atlas (TCGA) database was analyzed, and the effect of topotecan on the protein expression was examined by Western blotting.

RESULTS

Eleven topotecan signatures were downloaded, and 65 upregulated and 87 downregulated DEGs were identified. Twenty-one hub genes were identified. We identified eight key genes as upregulated genes, including NFKBIA, IKBKB, GADD45A, CDKN1A, and HIST2H2BE, while EZH2, CDC20, and CDK7 were identified as downregulated genes, which play critical roles in the cell cycle and carcinogenesis in KEGG analysis. In the TCGA analysis, the CDKN1A+/EZH2- group had the longest median survival, while the CDKN1A-/EZH2+ group had the shortest median survival. Topotecan-treated murine ovarian (MOSEC), colorectal (CT26), and lung (LLC) cancer cell lines displayed upregulated CDKN1A encoding p21 and downregulated Ezh2.

CONCLUSION

Using publicly accessible bioinformatics tools, we evaluated key genes and pathways related to topotecan and examined the key genes using the TCGA database and in vitro studies.

Hydrogen Ion Dynamics of Cancer and a New Molecular, Biochemical and Metabolic Approach to the Etiopathogenesis and Treatment of Brain Malignancies

The treatment of cancer has been slowly but steadily progressing during the last fifty years. Some tumors with a high mortality in the past are curable nowadays. However, there is one striking exception: glioblastoma multiforme. No real breakthrough has been hitherto achieved with this tumor with ominous prognosis and very short survival. Glioblastomas, being highly glycolytic malignancies are strongly pH-dependent and driven by the sodium hydrogen exchanger 1 (NHE1) and other proton (H⁺) transporters. Therefore, this is one of those pathologies where the lessons recently learnt from the new pH-centered anticancer paradigm may soon bring a promising change to treatment. This contribution will discuss how the pH-centric molecular, biochemical and metabolic perspective may introduce some urgently needed and integral novel treatments. Such a prospective therapeutic approach for malignant brain tumors is developed here, either to be used alone or in combination with more standard therapies.

Role of Radiation Therapy in the Management of Diffuse Intrinsic Pontine Glioma: A Systematic Review

Purpose

Diffuse intrinsic pontine glioma (DIPG) is the most aggressive primary pediatric brain tumor, with <10% of children surviving 2 years. Radiation therapy (RT) remains the mainstay of treatment, but there is a great clinical need for improvements and advancements in treatment strategies. The aim of this systematic review was to identify all available studies in which RT was used to treat patients with DIPG.

Methods and Materials

A literature search for studies published up to March 10, 2018 was conducted using the PubMed database. We identified 384 articles using search items “diffuse intrinsic pontine glioma” and 221 articles using search items “diffuse brainstem glioma radiotherapy.” Included studies were prospective and retrospective series that reported outcomes of DIPG treatment with RT.

Results

We identified 49 studies (1286 patients) using upfront conventionally fractionated RT, 5 studies (92 patients) using hypofractionated RT, and 8 studies (348 patients) using hyperfractionated RT. The mean median overall survival (OS) was 12.0 months, 10.2 months, and 7.9 months in patients who received conventional, hyperfractionated, and hypofractionated RT regimens, respectively. Patients undergoing radiosensitizing therapy had a mean median OS of 11.5 months, and patients who did not receive concomitant systemic therapy had an OS of 9.4 months. In patients who received salvage RT, the mean median OS from initial diagnosis was 16.3 months.

Conclusions

As one of the largest systematic reviews examining RT for DIPG, this report may serve as a useful tool to help clinicians choose the most appropriate treatment approach, while also providing a platform for future investigations into the utility of RT and systemic therapy.

Use of statins or NSAIDs and survival of patients with high-grade glioma

Background

High-grade glioma (HGG) is associated with a limited prognosis. Drug repurposing has become of increasing interest to improve standard therapy. Statins and NSAIDs inhibit glioma cell growth in vitro and in vivo, but data on statin and NSAID treatment in relation to survival of patients with HGG are sparse.

Methods

We performed multivariable adjusted Cox-regression analyses among 1,093 patients with HGG from a regional cancer registry to obtain Hazard Ratios (HRs) with 95% Confidence Intervals (CIs) for overall survival (OS) and progression-free survival (PFS) according to treatment with statins or NSAIDs. Data on dose and duration of treatment was mostly lacking in our analysis, therefore we were not able to perform dose-response analyses.

Results

Use of statins was unrelated to OS or PFS of glioma patients. Use of aspirin was associated with prolonged OS and PFS in patients with WHO grade III, but not WHO grade IV glioma. Use of other NSAIDs (diclofenac, ibuprofen) or non-NSAID analgesics (paracetamol) was mostly unrelated to survival of glioma patients. Use of selective COX-2 inhibitors and metamizol was related to inferior patient survival in parts of the analyses.

Conclusions

Use of statins or NSAIDS, including aspirin, was not associated with prolonged OS or PFS of patients with WHO grade IV glioma in our selected cohort. There was an indication for improved survival in patients with WHO grade III glioma using aspirin, but further studies are needed to confirm our first observation.

Drug Repurposing of Metabolic Agents in Malignant Glioma

Gliomas are highly invasive brain tumors with short patient survival. One major pathogenic factor is aberrant tumor metabolism, which may be targeted with different specific and unspecific agents. Drug repurposing is of increasing interest in glioma research. Drugs interfering with the patient’s metabolism may also influence glioma metabolism. In this review, we outline definitions and methods for drug repurposing. Furthermore, we give insights into important candidates for a metabolic drug repurposing, namely metformin, statins, non-steroidal anti-inflammatory drugs, disulfiram and lonidamine. Advantages and pitfalls of drug repurposing will finally be discussed.

Clinical, Radiologic, Pathologic, and Molecular Characteristics of Long-Term Survivors of Diffuse Intrinsic Pontine Glioma (DIPG): A Collaborative Report From the International and European Society for Pediatric Oncology DIPG Registries

Purpose Diffuse intrinsic pontine glioma (DIPG) is a brainstem malignancy with a median survival of < 1 year. The International and European Society for Pediatric Oncology DIPG Registries collaborated to compare clinical, radiologic, and histomolecular characteristics between short-term survivors (STSs) and long-term survivors (LTSs). Materials and Methods Data abstracted from registry databases included patients from North America, Australia, Germany, Austria, Switzerland, the Netherlands, Italy, France, the United Kingdom, and Croatia. Results Among 1,130 pediatric and young adults with radiographically confirmed DIPG, 122 (11%) were excluded. Of the 1,008 remaining patients, 101 (10%) were LTSs (survival ≥ 2 years). Median survival time was 11 months (interquartile range, 7.5 to 16 months), and 1-, 2-, 3-, 4-, and 5-year survival rates were 42.3% (95% CI, 38.1% to 44.1%), 9.6% (95% CI, 7.8% to 11.3%), 4.3% (95% CI, 3.2% to 5.8%), 3.2% (95% CI, 2.4% to 4.6%), and 2.2% (95% CI, 1.4% to 3.4%), respectively. LTSs, compared with STSs, more commonly presented at age < 3 or > 10 years (11% v 3% and 33% v 23%, respectively; P < .001) and with longer symptom duration ( P < .001). STSs, compared with LTSs, more commonly presented with cranial nerve palsy (83% v 73%, respectively; P = .008), ring enhancement (38% v 23%, respectively; P = .007), necrosis (42% v 26%, respectively; P = .009), and extrapontine extension (92% v 86%, respectively; P = .04). LTSs more commonly received systemic therapy at diagnosis (88% v 75% for STSs; P = .005). Biopsies and autopsies were performed in 299 patients (30%) and 77 patients (10%), respectively; 181 tumors (48%) were molecularly characterized. LTSs were more likely to harbor a HIST1H3B mutation (odds ratio, 1.28; 95% CI, 1.1 to 1.5; P = .002). Conclusion We report clinical, radiologic, and molecular factors that correlate with survival in children and young adults with DIPG, which are important for risk stratification in future clinical trials.

Molecular alterations in pediatric brainstem gliomas

BACKGROUND

Diffuse intrinsic pontine gliomas (DIPGs) have a dismal prognosis. Previously, diagnosis was based on a typical clinical presentation and magnetic resonance imaging findings. After the start of the era of biopsies, DIPGs bearing H3 K27 mutations have been reclassified into a novel entity, diffuse midline glioma, based on the presence of this molecular alteration. However, it is not well established how clinically diagnosed DIPG overlap with H3 K27-mutated diffuse midline gliomas, and whether rare long-term survivors also belong to this group.

METHODS

We studied tumor samples obtained at diagnosis or upon autopsy from 23 children, including two long-term survivors. Based on clinical, radiological, and histological findings, all tumors were previously diagnosed as DIPGs. All samples were analyzed for genetic alterations by next-generation sequencing (NGS) and for protein expression by immunohistochemistry (IHC).

RESULTS

H3 K27 was mutated in NGS or IHC in 20 patients, excluding both long-term survivors. One of these long-term survivors harbored a mutation in IDH1, formerly considered to be an alteration absent in pediatric diffuse brainstem gliomas. Other altered genes in NGS included TP53 (10 patients), MET and PDGFRA (3 patients each), VEGFR and SMARCA4 (2 patients each), and PPARγ, PTEN and EGFR in 1 patient, respectively. IHC revealed cMYC expression in 15 of 24 (63%) of all samples, exclusively in the biopsies.

CONCLUSIONS

Eighty-seven percent of the tumors formerly diagnosed as DIPGs could be reclassified as H3 K27-mutated diffuse midline gliomas. Both long-term survivors lacked this alteration. Contrary to former conceptions, IDH1 mutations may occur also in pediatric brainstem gliomas.

Molecular Guided Therapy Provides Sustained Clinical Response in Refractory Choroid Plexus Carcinoma

Choroid plexus carcinomas (CPCs) are rare, aggressive pediatric brain tumors with no established curative therapy for relapsed disease, and poor survival rates. TP53 Mutation or dysfunction correlates with poor or no survival outcome in CPCs. Here, we report the case of a 4 month-old female who presented with disseminated CPC. After initial response to tumor resection and adjuvant-chemotherapy, the tumor recurred and metastasized with no response to aggressive relapse therapy suggesting genetic predisposition. This patient was then enrolled to a Molecular Guided Therapy Clinical Trial. Genomic profiling of patient tumor and normal sample identified a TP53 germline mutation with loss of heterozygosity, somatic mutations including IDH2, and aberrant activation of biological pathways. The mutations were not targetable for therapy. However, targeting the altered biological pathways (mTOR, PDGFRB, FGF2, HDAC) guided identification of possibly beneficial treatment with a combination of sirolimus, thalidomide, sunitinib, and vorinostat. This therapy led to 92% reduction in tumor size with no serious adverse events, excellent quality of life and long term survival.

Vascular Endothelial Growth Factor, Irradiation, and Axitinib Have Diverse Effects on Motility and Proliferation of Glioblastoma Multiforme Cells

Glioblastoma multiforme (GBM) is the most common primary brain tumor. It is highly aggressive with an unfavorable prognosis for the patients despite therapies including surgery, irradiation, and chemotherapy. One important characteristic of highly vascularized GBM is the strong expression of vascular endothelial growth factor (VEGF). VEGF has become a new target in the treatment of GBM, and targeted therapies such as the VEGF-receptor blocker axitinib are in clinical trials. Most studies focus on VEGF-induced angiogenesis, but only very few investigations analyze autocrine or paracrine effects of VEGF on the tumor cells. In this study, we examined the impact of VEGF, irradiation, and axitinib on cell proliferation and cell motility in human GBM cell lines U-251 and U-373. VEGF receptor 2 was shown to be expressed within both cell lines by using PCR and immunochemistry. Moreover, we performed 24-h videography to analyze motility, and a viability assay for cell proliferation. We observed increasing effects of VEGF and irradiation on cell motility in both cell lines, as well as strong inhibiting effects on cellular motility by VEGF-receptor blockade using axitinib. Moreover, axitinib diminished irradiation induced accelerating effects. While VEGF stimulation or irradiation did not affect cell proliferation, axitinib significantly decreased cell proliferation in both cell lines. Therefore, the impairment of VEGF signaling might have a crucial role in the treatment of GBM.

Second re-irradiation for DIPG progression, re-considering "old strategies" with new approaches

Diffuse intrinsic pontine glioma (DIPG) is an aggressive infiltrative glioma for which no curative therapy is available. Radiation therapy (RT) is the only potentially effective intervention in delaying tumor progression, but only transiently. At progression, re-irradiation is gaining popularity as an effective palliative therapy. However, at second progression, exclusive symptomatic treatment is usually offered. Here we report two patients with DIPG at second progression who were treated with a second re-irradiation course with good response. Importantly, treatment was well tolerated with no irradiation associated acute toxicity identified.

Genomic Insights into Diffuse Intrinsic Pontine Glioma

Diffuse intrinsic pontine glioma (DIPG) is a highly aggressive pediatric brainstem tumor with a peak incidence in middle childhood and a median survival of less than 1 year. The dismal prognosis associated with DIPG has been exacerbated by the failure of over 250 clinical trials to meaningfully improve survival compared with radiotherapy, the current standard of care. The traditional practice to not biopsy DIPG led to a scarcity in available tissue samples for laboratory analysis that till recently hindered therapeutic advances. Over the past few years, the acquisition of patient derived tumor samples through biopsy and autopsy protocols has led to distinct breakthroughs in the identification of key oncogenic drivers implicated in DIPG development. Aberrations have been discovered in critical genetic drivers including histone H3, ACVR1, TP53, PDGFRA, and Myc. Mutations, previously not identified in other malignancies, highlight DIPG as a distinct biological entity. Identification of novel markers has already greatly influenced the direction of preclinical investigations and offers the exciting possibility of establishing biologically targeted therapies. This review will outline the current knowledge of the genomic landscape related to DIPG, overview preclinical investigations, and reflect how biological advances have influenced the focus of clinical trials toward targeted therapies.

Metronomic therapy can increase quality of life during paediatric palliative cancer care, but careful patient selection is essential

AIM

Children with refractory or high-risk malignancies frequently suffer from poor quality of life during palliative care. This study explored the effect of metronomic drug administration on survival and quality of life in paediatric patients with various refractory or high-risk tumours.

METHODS

We treated 17 patients with a maintenance therapy that consisted of metronomic thalidomide, etoposide and celecoxib. The endpoints of the study were overall and progression-free survival, changes in the Karnofsky-Lansky scores from baseline to the end of the study therapy and radiological responses.

RESULTS

The median overall survival after the start of the study therapy was 6.2 months (range 2.0-57.7), and the six-, 12- and 24-month survival rates were 59%, 18% and 18%, respectively. The median progression-free survival was 3.2 months (range 0.3-17.8). The Karnofsky-Lansky scores increased significantly during the study therapy (p = 0.02), with 35% of the patients having a transient improvement in their clinical status. Radiologically, one partial response and two disease stabilisations were encountered. Grade III-V adverse events occurred in 76% of the patients.

CONCLUSION

Metronomic therapy may increase the quality of life during palliative care for childhood cancer, but requires careful patient selection to minimise the risk of serious adverse events.

The use of cyclooxygenase-2 inhibitors for improvement of efficacy of radiotherapy in cancers

Cyclooxygenase-2 (COX-2) is overexpressed in cancer cells and is associated with carcinogenesis and maintenance of progressive tumour growth as well as resistance of cancer cells to ionising radiation (IR). COX-2 inhibitors can attenuate tumour growth and expression of markers of cell proliferation as well as induce apoptosis in tumour cells. These agents can have a synergistic effect with IR in the killing of cancer cells. In this review, we discuss the rational basis and molecular mechanisms regarding the usefulness of COX-2 inhibitors in cancer therapy, and also their potential role in increasing the therapeutic index of chemoradiation by protecting normal cells and sensitising tumour cells to radiotherapy.

Pathology, Molecular Genetics, and Epigenetics of Diffuse Intrinsic Pontine Glioma

Diffuse intrinsic pontine glioma (DIPG) is a devastating pediatric brain cancer with no effective therapy. Histological similarity of DIPG to supratentorial high-grade astrocytomas of adults has led to assumptions that these entities possess similar underlying molecular properties and therefore similar therapeutic responses to standard therapies. The failure of all clinical trials in the last 30 years to improve DIPG patient outcome has suggested otherwise. Recent studies employing next-generation sequencing and microarray technologies have provided a breadth of evidence highlighting the unique molecular genetics and epigenetics of this cancer, distinguishing it from both adult and pediatric cerebral high-grade astrocytomas. This review describes the most common molecular genetic and epigenetic signatures of DIPG in the context of molecular subgroups and histopathological diagnosis, including this tumor entity's unique mutational landscape, copy number alterations, and structural variants, as well as epigenetic changes on the global DNA and histone levels. The increased knowledge of DIPG biology and histopathology has opened doors to new diagnostic and therapeutic avenues.