Phase I study of vandetanib during and after radiotherapy in children with 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.

H3K27-Altered Diffuse Midline Glioma of the Brainstem: From Molecular Mechanisms to Targeted Interventions

Pediatric high-grade gliomas are a devastating subset of brain tumors, characterized by their aggressive pathophysiology and limited treatment options. Among them, H3 K27-altered diffuse midline gliomas (DMG) of the brainstem stand out due to their distinct molecular features and dismal prognosis. Recent advances in molecular profiling techniques have unveiled the critical role of H3 K27 alterations, particularly a lysine-to-methionine mutation on position 27 (K27M) of the histone H3 tail, in the pathogenesis of DMG. These mutations result in epigenetic dysregulation, which leads to altered chromatin structure and gene expression patterns in DMG tumor cells, ultimately contributing to the aggressive phenotype of DMG. The exploration of targeted therapeutic avenues for DMG has gained momentum in recent years. Therapies, including epigenetic modifiers, kinase inhibitors, and immunotherapies, are under active investigation; these approaches aim to disrupt aberrant signaling cascades and overcome the various mechanisms of therapeutic resistance in DMG. Challenges, including blood-brain barrier penetration and DMG tumor heterogeneity, require innovative approaches to improve drug delivery and personalized treatment strategies. This review aims to provide a comprehensive overview of the evolving understanding of DMG, focusing on the intricate molecular mechanisms driving tumorigenesis/tumor progression and the current landscape of emerging targeted interventions.

H3 K27M-altered glioma and diffuse intrinsic pontine glioma: Semi-systematic review of treatment landscape and future directions

H3 K27M-mutant diffuse glioma is a recently identified brain tumor associated with poor prognosis. As of 2016, it is classified by the World Health Organization as a distinct form of grade IV glioma. Despite recognition as an important prognostic and diagnostic feature in diffuse glioma, radiation remains the sole standard of care and no effective systemic therapies are available for H3K27M mutant tumors. This review will detail treatment interventions applied to diffuse midline glioma and diffuse intrinsic pontine glioma (DIPG) prior to the identification of the H3 K27M mutation, the current standard-of-care for H3 K27M-mutant diffuse glioma treatment, and ongoing clinical trials listed on www.clinicaltrials.gov evaluating novel therapeutics in this population. Current clinical trials were identified using clinicaltrials.gov, and studies qualifying for this analysis were active or ongoing interventional trials that evaluated a therapy in at least 1 treatment arm or cohort comprised exclusively of patients with DIPG and H3 K27M-mutant glioma. Forty-one studies met these criteria, including trials evaluating H3 K27M vaccination, chimeric antigen receptor T-cell therapy, and small molecule inhibitors. Ongoing evaluation of novel therapeutics is necessary to identify safe and effective interventions in this underserved patient population.

A phase 1 trial utilizing a pharmacokinetic endpoint to determine the optimal dose of ramucirumab in children and adolescents with relapsed or refractory solid tumors, including central nervous system tumors

BACKGROUND

Ramucirumab is a monoclonal antibody that binds the extracellular domain of vascular endothelial growth factor receptor (VEGFR-2) and prevents binding of VEGF ligands. Based on population pharmacokinetic (PK) analysis and correlation with efficacy in adults, a target steady state trough concentration (Css,min ) ≥ 50 µg/mL was established.

PROCEDURES

This phase 1 trial (ADVL1416) used a rolling six design and a PK primary endpoint to define the recommended phase 2 dose (RP2D) of ramucirumab in children with recurrent/refractory solid tumors. Two dose levels (DL) were planned (DL1: 8 mg/kg, DL2: 12 mg/kg administered intravenously [IV] every 2 weeks). Toxicity during the initial 6 weeks was used to assess maximum tolerated dose (MTD). Cycle 1 Day 42 trough (Cmin ) ≥ 50 µg/mL was the target concentration for the PK endpoint. At the RP2D, cohorts for PK expansion and children with central nervous tumors were planned.

RESULTS

Twenty-nine patients were enrolled; 28 were eligible; median age [range] = 13.5 [1-21] years; 22 were evaluable for the PK endpoint. Dose-limiting proteinuria occurred at both DLs; however, the MTD was not exceeded. At DL2 (12 mg/kg), the median Day 42 Cmin (n = 16) was 87.8 µg/mL; 15 of 16 patients achieved a Cmin  ≥ 50 µg/mL.

CONCLUSION

Ramucirumab was well tolerated in children and adolescents with solid tumors. The RP2D for ramucirumab was 12 mg/kg IV every 2 weeks. This trial demonstrates the feasibility of incorporating a primary PK endpoint to determine dose escalation and the RP2D in children. Studies of ramucirumab in children with selected solid tumors are ongoing.

PI3K/mTOR is a therapeutically targetable genetic dependency in diffuse intrinsic pontine glioma

Diffuse midline glioma (DMG), including tumors diagnosed in the brainstem (diffuse intrinsic pontine glioma; DIPG), are uniformly fatal brain tumors that lack effective treatment. Analysis of CRISPR/Cas9 loss-of-function gene deletion screens identified PIK3CA and MTOR as targetable molecular dependencies across patient derived models of DIPG, highlighting the therapeutic potential of the blood-brain barrier-penetrant PI3K/Akt/mTOR inhibitor, paxalisib. At the human-equivalent maximum tolerated dose, mice treated with paxalisib experienced systemic glucose feedback and increased insulin levels commensurate with patients using PI3K inhibitors. To exploit genetic dependence and overcome resistance while maintaining compliance and therapeutic benefit, we combined paxalisib with the antihyperglycemic drug metformin. Metformin restored glucose homeostasis and decreased phosphorylation of the insulin receptor in vivo, a common mechanism of PI3K-inhibitor resistance, extending survival of orthotopic models. DIPG models treated with paxalisib increased calcium-activated PKC signaling. The brain penetrant PKC inhibitor enzastaurin, in combination with paxalisib, synergistically extended the survival of multiple orthotopic patient-derived and immunocompetent syngeneic allograft models; benefits potentiated in combination with metformin and standard-of-care radiotherapy. Therapeutic adaptation was assessed using spatial transcriptomics and ATAC-Seq, identifying changes in myelination and tumor immune microenvironment crosstalk. Collectively, this study has identified what we believe to be a clinically relevant DIPG therapeutic combinational strategy.

Advances in Treatment of Diffuse Midline Gliomas

PURPOSE OF REVIEW

Diffuse midline gliomas (DMGs) generally carry a poor prognosis, occur during childhood, and involve midline structures of the central nervous system, including the thalamus, pons, and spinal cord.

RECENT FINDINGS

To date, irradiation has been shown to be the only beneficial treatment for DMG. Various genetic modifications have been shown to play a role in the pathogenesis of this disease. Current treatment strategies span targeting epigenetic dysregulation, cell cycle, specific genetic alterations, and the immune microenvironment. Herein, we review the complex features of this disease as it relates to current and past therapeutic approaches.

Radiotherapy and radio-sensitization in H3K27M -mutated diffuse midline gliomas

BACKGROUND

H3^K27M mutated diffuse midline gliomas (DMGs) are extremely aggressive and the leading cause of cancer-related deaths in pediatric brain tumors with 5-year survival <1%. Radiotherapy is the only established adjuvant treatment of H3^K27M DMGs; however, the radio-resistance is commonly observed.

METHODS

We summarized current understandings of the molecular responses of H3^K27M DMGs to radiotherapy and provide crucial insights into current advances in radiosensitivity enhancement.

RESULTS

Ionizing radiation (IR) can mainly inhibit tumor cell growth by inducing DNA damage regulated by the cell cycle checkpoints and DNA damage repair (DDR) system. In H3K27M DMGs, the aberrant genetic and epigenetic changes, stemness genotype, and epithelial-mesenchymal transition (EMT) disrupt the cell cycle checkpoints and DDR system by altering the associated regulatory signaling pathways, which leads to the development of radio-resistance.

CONCLUSIONS

The advances in mechanisms of radio-resistance in H3^K27M  DMGs promote the potential targets to enhance the sensitivity to radiotherapy.

Pediatric Diffuse Midline Gliomas: An Unfinished Puzzle

Diffuse midline glioma (DMG) is a heterogeneous group of aggressive pediatric brain tumors with a fatal prognosis. The biological hallmark in the major part of the cases is H3K27 alteration. Prognosis remains poor, with median survival ranging from 9 to 12 months from diagnosis. Clinical and radiological prognostic factors only partially change the progression-free survival but they do not improve the overall survival. Despite efforts, there is currently no curative therapy for DMG. Radiotherapy remains the standard treatment with only transitory benefits. No chemotherapeutic regimens were found to significantly improve the prognosis. In the new era of a deeper integration between histological and molecular findings, potential new approaches are currently under investigation. The entire international scientific community is trying to target DMG on different aspects. The therapeutic strategies involve targeting epigenetic alterations, such as methylation and acetylation status, as well as identifying new molecular pathways that regulate oncogenic proliferation; immunotherapy approaches too are an interesting point of research in the oncology field, and the possibility of driving the immune system against tumor cells has currently been evaluated in several clinical trials, with promising preliminary results. Moreover, thanks to nanotechnology amelioration, the development of innovative delivery approaches to overcross a hostile tumor microenvironment and an almost intact blood-brain barrier could potentially change tumor responses to different treatments. In this review, we provide a comprehensive overview of available and potential new treatments that are worldwide under investigation, with the intent that patient- and tumor-specific treatment could change the biological inauspicious history of this disease.

Receptor tyrosine kinase (RTK) targeting in pediatric high-grade glioma and diffuse midline glioma: Pre-clinical models and precision medicine

Pediatric high-grade glioma (pHGG), including both diffuse midline glioma (DMG) and non-midline tumors, continues to be one of the deadliest oncologic diagnoses (both henceforth referred to as “pHGG”). Targeted therapy options aimed at key oncogenic receptor tyrosine kinase (RTK) drivers using small-molecule RTK inhibitors has been extensively studied, but the absence of proper in vivo modeling that recapitulate pHGG biology has historically been a research challenge. Thankfully, there have been many recent advances in animal modeling, including Cre-inducible transgenic models, as well as intra-uterine electroporation (IUE) models, which closely recapitulate the salient features of human pHGG tumors. Over 20% of pHGG have been found in sequencing studies to have alterations in platelet derived growth factor-alpha (PDGFRA), making growth factor modeling and inhibition via targeted tyrosine kinases a rich vein of interest. With commonly found alterations in other growth factors, including FGFR, EGFR, VEGFR as well as RET, MET, and ALK, it is necessary to model those receptors, as well. Here we review the recent advances in murine modeling and precision targeting of the most important RTKs in their clinical context. We additionally provide a review of current work in the field with several small molecule RTK inhibitors used in pre-clinical or clinical settings for treatment of pHGG.

Next-Generation Anti-Angiogenic Therapies as a Future Prospect for Glioma Immunotherapy; From Bench to Bedside

Glioblastoma (grade IV glioma) is the most aggressive histopathological subtype of glial tumors with inordinate microvascular proliferation as one of its key pathological features. Extensive angiogenesis in the tumor microenvironment supplies oxygen and nutrients to tumoral cells; retains their survival under hypoxic conditions; and induces an immunosuppressive microenvironment. Anti-angiogenesis therapy for high-grade gliomas has long been studied as an adjuvant immunotherapy strategy to overcome tumor growth. In the current review, we discussed the underlying molecular mechanisms contributing to glioblastoma aberrant angiogenesis. Further, we discussed clinical applications of monoclonal antibodies, tyrosine kinase inhibitors, and aptamers as three major subgroups of anti-angiogenic immunotherapeutics and their limitations. Moreover, we reviewed clinical and preclinical applications of small interfering RNAs (siRNAs) as the next-generation anti-angiogenic therapeutics and summarized their potential advantages and limitations. siRNAs may serve as next-generation anti-angiogenic therapeutics for glioma. Additionally, application of nanoparticles as a delivery vehicle could increase their selectivity and lower their off-target effects.

Repurposing Vandetanib plus Everolimus for the Treatment of ACVR1-Mutant Diffuse Intrinsic Pontine Glioma

Somatic mutations in ACVR1 are found in a quarter of children with diffuse intrinsic pontine glioma (DIPG), but there are no ACVR1 inhibitors licensed for the disease. Using an artificial intelligence-based platform to search for approved compounds for ACVR1-mutant DIPG, the combination of vandetanib and everolimus was identified as a possible therapeutic approach. Vandetanib, an inhibitor of VEGFR/RET/EGFR, was found to target ACVR1 (K d = 150 nmol/L) and reduce DIPG cell viability in vitro but has limited ability to cross the blood-brain barrier. In addition to mTOR, everolimus inhibited ABCG2 (BCRP) and ABCB1 (P-gp) transporters and was synergistic in DIPG cells when combined with vandetanib in vitro. This combination was well tolerated in vivo and significantly extended survival and reduced tumor burden in an orthotopic ACVR1-mutant patient-derived DIPG xenograft model. Four patients with ACVR1-mutant DIPG were treated with vandetanib plus an mTOR inhibitor, informing the dosing and toxicity profile of this combination for future clinical studies. SIGNIFICANCE: Twenty-five percent of patients with the incurable brainstem tumor DIPG harbor somatic activating mutations in ACVR1, but there are no approved drugs targeting the receptor. Using artificial intelligence, we identify and validate, both experimentally and clinically, the novel combination of vandetanib and everolimus in these children based on both signaling and pharmacokinetic synergies.This article is highlighted in the In This Issue feature, p. 275.

Therapeutic Targets in Diffuse Midline Gliomas-An Emerging Landscape

Simple Summary

Diffuse midline gliomas (DMGs) remain one of the most devastating childhood brain tumour types, for which there is currently no known cure. In this review we provide a summary of the existing knowledge of the molecular mechanisms underlying the pathogenesis of this disease, highlighting current analyses and novel treatment propositions. Together, the accumulation of these data will aid in the understanding and development of more effective therapeutic options for the treatment of DMGs.

Abstract

Diffuse midline gliomas (DMGs) are invariably fatal pediatric brain tumours that are inherently resistant to conventional therapy. In recent years our understanding of the underlying molecular mechanisms of DMG tumorigenicity has resulted in the identification of novel targets and the development of a range of potential therapies, with multiple agents now being progressed to clinical translation to test their therapeutic efficacy. Here, we provide an overview of the current therapies aimed at epigenetic and mutational drivers, cellular pathway aberrations and tumor microenvironment mechanisms in DMGs in order to aid therapy development and facilitate a holistic approach to patient treatment.

Dermatologic toxicities of targeted antineoplastic agents and immune checkpoint inhibitor therapy in pediatric patients: A systematic review

Cutaneous adverse events (cAEs) from targeted antineoplastic agents and immune checkpoint inhibitors are common in children with cancer and may lead to dose reduction or cessation of critical oncologic treatment. Timely diagnosis and proper management of cAEs in pediatric oncology patients is essential to optimize ongoing cancer-directed therapy and improve quality of life. This systematic review of published studies summarizes dermatologic toxicities to targeted anticancer treatments and immune checkpoint inhibitors.

[Diffuse brainstem tumors in children. Tumor biology and hope for a better outcome. Current state of the problem]

Diffuse brainstem tumor is a fatal disease and the main cause of child mortality from neoplasms of central nervous system. So far, no effective therapy has been found for this disease. The authors discuss the modern aspects of clinical data, biology, diagnosis and treatment of patients with diffuse brainstem tumors.

Radiosensitization in Pediatric High-Grade Glioma: Targets, Resistance and Developments

Pediatric high-grade gliomas (pHGG) are the leading cause of cancer-related death in children. These epigenetically dysregulated tumors often harbor mutations in genes encoding histone 3, which contributes to a stem cell-like, therapy-resistant phenotype. Furthermore, pHGG are characterized by a diffuse growth pattern, which, together with their delicate location, makes complete surgical resection often impossible. Radiation therapy (RT) is part of the standard therapy against pHGG and generally the only modality, apart from surgery, to provide symptom relief and a delay in tumor progression. However, as a single treatment modality, RT still offers no chance for a cure. As with most therapeutic approaches, irradiated cancer cells often acquire resistance mechanisms that permit survival or stimulate regrowth after treatment, thereby limiting the efficacy of RT. Various preclinical studies have investigated radiosensitizers in pHGG models, without leading to an improved clinical outcome for these patients. However, our recently improved molecular understanding of pHGG generates new opportunities to (re-)evaluate radiosensitizers in these malignancies. Furthermore, the use of radio-enhancing agents has several benefits in pHGG compared to other cancers, which will be discussed here. This review provides an overview and a critical evaluation of the radiosensitization strategies that have been studied to date in pHGG, thereby providing a framework for improving radiosensitivity of these rapidly fatal brain tumors.

Receptor Tyrosine Kinases: Principles and Functions in Glioma Invasion

Protein tyrosine kinases are enzymes that are capable of adding a phosphate group to specific tyrosines on target proteins. A receptor tyrosine kinase (RTK) is a tyrosine kinase located at the cellular membrane and is activated by binding of a ligand via its extracellular domain. Protein phosphorylation by kinases is an important mechanism for communicating signals within a cell and regulating cellular activity; furthermore, this mechanism functions as an "on" or "off" switch in many cellular functions. Ninety unique tyrosine kinase genes, including 58 RTKs, were identified in the human genome; the products of these genes regulate cellular proliferation, survival, differentiation, function, and motility. Tyrosine kinases play a critical role in the development and progression of many types of cancer, in addition to their roles as key regulators of normal cellular processes. Recent studies have revealed that RTKs such as epidermal growth factor receptor (EGFR), platelet-derived growth factor receptor (PDGFR), c-Met, Tie, Axl, discoidin domain receptor 1 (DDR1), and erythropoietin-producing human hepatocellular carcinoma (Eph) play a major role in glioma invasion. Herein, we summarize recent advances in understanding the role of RTKs in glioma pathobiology, especially the invasive phenotype, and present the perspective that RTKs are a potential target of glioma therapy.

Radiation dose response of neurologic symptoms during conformal radiotherapy for diffuse intrinsic pontine glioma

PURPOSE

To estimate the rate and magnitude of neurologic symptom change during radiation therapy (RT) and impact of symptom change on survival outcomes in patients with diffuse intrinsic pontine glioma (DIPG).

METHODS

From 2006 to 2014, 108 patients with newly diagnosed DIPG were treated with conventionally fractionated radiation therapy (RT) to 54 Gy (median) at our institution. The presence and severity of neurologic symptoms related to cranial neuropathy (CN) and cerebellar (CB) and long-tract (LT) signs was reviewed before and weekly during RT for each patient. The rate and magnitude of change for each symptom category was evaluated according to accumulated RT dose. The impact of clinical factors and radiation dose-volume parameters was determined using Cox proportional hazards models.

RESULTS

Median dose to first sign of symptomatic improvement was 16.2 Gy (CN), 19.8 Gy (LT) and 21.6 Gy (CB). Most patients showed an improvement by 20 Gy. Larger uninvolved brainstem volume, alone or normalized to total brain (TB) or posterior fossa volume (PF), was associated with shorter time to LT sign improvement (P = 0.044, P = 0.033, and P = 0.05, respectively). Patients with any improvement in CN experienced significantly, yet modestly, prolonged progression-free survival (PFS) and overall survival (OS) (P = 0.002 and P = 0.008, respectively). Tumor volume, with or without normalization to TB or PF, was not significantly associated with PFS or OS.

CONCLUSIONS

Low cumulative RT doses resulted in neurologic improvement in most patients with DIPG. The volume of brainstem spared by tumor influenced time to symptomatic improvement. Neurologic improvement during RT was associated with superior survival.

MRI Patterns of Extrapontine Lesion Extension in Diffuse Intrinsic Pontine Gliomas

BACKGROUND AND PURPOSE

Diffuse intrinsic pontine glioma is a devastating childhood cancer that despite being primarily diagnosed by MR imaging alone, lacks robust prognostic imaging features. This study investigated patterns and quantification of extrapontine lesion extensions as potential prognostic imaging biomarkers for survival in children with newly diagnosed diffuse intrinsic pontine glioma.

MATERIALS AND METHODS

Volumetric analysis of baseline MR imaging studies was completed in 131 patients with radiographically defined typical diffuse intrinsic pontine gliomas. Extrapontine tumor extension was classified according to the direction of extension: midbrain, medulla oblongata, and right and left middle cerebellar peduncles; various extrapontine lesion extension patterns were evaluated. The Kaplan-Meier method was used to estimate survival differences; linear regression was used to evaluate clinical-radiographic variables prognostic of survival.

RESULTS

At least 1 extrapontine lesion extension was observed in 125 patients (95.4%). Of the 11 different extrapontine lesion extension patterns encountered in our cohort, 2 were statistically significant predictors of survival. Any extension into the middle cerebellar peduncles was prognostic of shorter overall survival (P = .01), but extension into both the midbrain and medulla oblongata but without extension into either middle cerebellar peduncle was prognostic of longer overall survival compared with those having no extension (P = .04) or those having any other pattern of extension (P < .001).

CONCLUSIONS

Within this large cohort of patients with typical diffuse intrinsic pontine gliomas, 2 specific extrapontine lesion extension patterns were associated with a significant overall survival advantage or disadvantage. Our findings may be valuable for risk stratification and radiation therapy planning in future clinical trials.

STAT Signaling in Glioma Cells

STAT (signal transducers and activators of transcription) are latent cytoplasmic transcription factors that function as downstream effectors of cytokine and growth factor receptor signaling. The canonical JAK/STAT signaling pathway involves the activation of Janus kinases (JAK) or growth factors receptor kinases, phosphorylation of STAT proteins, their dimerization and translocation into the nucleus where STATs act as transcription factors with pleiotropic downstream effects. STAT signaling is tightly controlled with restricted kinetics due to action of its negative regulators. While STAT1 is believed to play an important role in growth arrest and apoptosis, and to act as a tumor suppressor, STAT3 and 5 are involved in promoting cell cycle progression, cellular transformation, and preventing apoptosis. Aberrant activation of STATs, in particular STAT3 and STAT5, have been found in a large number of human tumors, including gliomas and may contribute to oncogenesis. In this chapter, we have (1) summarized the mechanisms of STAT activation in normal and malignant signaling; (2) discussed evidence for the critical role of constitutively activated STAT3 and STAT5 in glioma pathobiology; (3) disclosed molecular and pharmacological strategies to interfere with STAT signaling for potential therapeutic intervention in gliomas.

Defining Optimal Target Volumes of Conformal Radiation Therapy for Diffuse Intrinsic Pontine Glioma

PURPOSE

Optimal radiation therapy (RT) target margins for diffuse intrinsic pontine glioma (DIPG) are unknown. We sought to define disease progression patterns in a contemporary cohort treated with conformal RT using different clinical target volume (CTV) margins.

METHODS AND MATERIALS

We reviewed 105 patients with newly diagnosed DIPG treated with conformal conventionally fractionated RT at our institution from 2006 to 2014. CTV margins were classified as standard (1 cm) for 60 patients and extended (2-3 cm) for 45 patients. Survival and cumulative incidence of progression in treatment groups were compared by log-rank and Gray's tests, respectively. Cox proportional hazard models identified predictors of survival.

RESULTS

For 97 patients evaluated with magnetic resonance imaging at progression, the cumulative incidences of isolated local, isolated distant, and synchronous disease progression at 1 year were 62.6%, 12.3%, and 7.2%, respectively, and did not differ significantly according to the CTV margin. Central dosimetric progression (V_progression95% ≥95%) was observed in 80 of 81 evaluable patients. Median progression-free survival and overall survival (OS) were 7.6 months (95% confidence interval, 6.9-8.2) and 11.3 months (95% confidence interval, 10.0-12.8), respectively, and did not differ significantly according to margin status. DIPG survival prediction risk group (standard vs high, P = .02; intermediate vs high, P = .009) and development of distant metastasis (P = .003) were independent predictors of OS. For the 41 patients (39%) with a pathologic diagnosis, H3.3 K27M mutation was associated with shorter OS (hazard ratio [HR], 0.41; P =.02), whereas H3.1 K27M and ACVR1 mutations were associated with longer OS (HR, 3.56; P =.004 and HR, 2.58; P =.04, respectively).

CONCLUSIONS

All patients who experienced local failure showed progression within the high-dose volume, and there was no apparent survival or tumor-control benefit to extending the CTV margins beyond 1 cm. Given the increasing use of reirradiation, standardizing the CTV margin to 1 cm may improve retreatment tolerance.

Diffuse Intrinsic Pontine Glioma: From Diagnosis to Next-Generation Clinical Trials

PURPOSE OF REVIEW

This review of diffuse intrinsic pontine glioma (DIPG) provides clinical background, a systematic approach to diagnosis and initial care, and synthesizes historical, modern, and future directions for treatment. We present evidence supporting neurosurgical biopsy, early palliative care involvement, limitation of glucocorticoid use, and the leveraging of preclinical DIPG models as a pipeline to next-generation clinical trials.

RECENT FINDINGS

New molecular understanding of pediatric high-grade gliomas has led to the reclassification of DIPG as one member of a family of diffuse gliomas occurring in the midline of the central nervous system that exhibit pathognomonic mutations in genes encoding histone 3 (H3 K27M). DIPG remains a clinically relevant term, though diagnostically the 80% of DIPG cases that exhibit the H3 K27M mutation have been reclassified as diffuse midline glioma, H3 K27M-mutant. Re-irradiation has been shown to be well-tolerated and of potential benefit. Epigenetic targeting of transcriptional dependencies in preclinical models is fueling molecularly targeted clinical trials. Chimeric antigen receptor T cell immunotherapy has also demonstrated efficacy in preclinical models and provides a promising new clinical strategy. DIPG is a universally fatal, epigenetically driven tumor of the pons that is considered part of a broader class of diffuse midline gliomas sharing H3 K27M mutations. Radiation remains the standard of care, single-agent temozolomide is not recommended, and glucocorticoids should be used only sparingly. A rapid evolution of understanding in the chromatin, signaling, and immunological biology of DIPG may soon result in clinical breakthroughs.

Activation of STAT1 by the FRK tyrosine kinase is associated with human glioma growth

PURPOSE

Glioma is a highly aggressive and lethal brain tumor. Signal transducers and activators of transcription (STAT) pathway are widely implicated in glioma carcinogenesis. Our previous study found that the Fynrelated kinase (FRK) gene, plays as a tumor suppressor in the development and progression of glioma. This study aimed to investigate the role of FRK in the activation pathway of STATs and its effect on the growth of glioma.

METHODS

The U251 and U87 cells with stable FRK overexpression were generated by lentivirus technique. The effects of FRK on the related proteins of STAT signaling pathway were detected by western blotting. Coimmunoprecipitation was used to detect the association of FRK and STAT1. The effects of STAT1 on the proliferation of glioma cells were detected by CCK8 or Edu cell proliferation assays. The expressions and correlation of FRK and p-STAT1 in glioma tissues were detectd by western blotting or immunohistochemistry. The effect of FRK on the growth of glioma was investigated in vivo mouse model.

RESULTS

The level of p-JAK2 and p-STAT1 increased after FRK overexpression, while they decreased after FRK downregulation both in U251 and U87 cells. However, FRK had no effect on STAT3 phosphorylation. FRK-induced STAT1 activation was not dependent on JAK2. FRK associated with STAT1, induced STAT1 nuclear translocation and regulated the expressions of STAT1-related target genes. STAT1 overexpression suppressed the proliferation of glioma cells. In contrast, STAT1 knockdown by siRNA promoted glioma cell growth. Importantly, down-regulation of STAT1 partially attenuated FRK-induced growth suppression. The clinical sample-based study indicated that the expression of FRK was significantly correlated with the expression of p-STAT1. FRK significantly inhibited glioma tumor growth in vivo.

CONCLUSIONS

Our findings highlighted a critical role of FRK in tumor suppression ability through promoting STAT1 activation, and provided a potential therapeutic target for glioma.

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.

Nimotuzumab and radiotherapy for treatment of newly diagnosed diffuse intrinsic pontine glioma (DIPG): a phase III clinical study

BACKGROUND

Diffuse intrinsic pontine glioma (DIPG) is a devastating cancer of childhood and adolescence.

METHODS

The study included patients between 3 and 20 years with clinically and radiologically confirmed DIPG. Primary endpoint was 6-month progression-free survival (PFS) following administration of nimotuzumab in combination with external beam radiotherapy (RT). Nimotuzumab was administered intravenously at 150 mg/m² weekly for 12 weeks. Radiotherapy at total dose of 54 Gy was delivered between week 3 and week 9. Response was evaluated based on clinical features and MRI findings according to RECIST criteria at week 12. Thereafter, patients continued to receive nimotuzumab every alternate week until disease progression/unmanageable toxicity. Adverse events (AE) were evaluated according to Common Terminology Criteria for Adverse Events (CTC-AE) Version 3.0 (CTC-AE3).

RESULTS

All 42 patients received at least one dose of nimotuzumab in outpatient settings. Two patients had partial response (4.8%), 27 had stable disease (64.3%), 10 had progressive disease (23.8%) and 3 patients (7.1%) could not be evaluated. The objective response rate (ORR) was 4.8%. Median PFS was 5.8 months and median overall survival (OS) was 9.4 months. Most common drug-related AEs were alopecia (14.3%), vomiting, headache and radiation skin injury (7.1% each). Therapy-related serious adverse events (SAEs) were intra-tumoral bleeding and acute respiratory failure, which were difficult to distinguish from effects of tumor progression.

CONCLUSIONS

Concomitant treatment with RT and nimotuzumab was feasible in an outpatient setting. The PFS and OS were comparable to results achieved with RT and intensive chemotherapy in hospitalized setting.

Lack of value of juvenile animal toxicity studies for supporting the safety of pediatric oncology phase I trials

Toxicity studies in juvenile animals (JAS) are sometimes performed to support clinical trials in pediatric oncology patients, and there are differing conclusions on the value of JAS for pediatric drug development. This manuscript provides a review of the pediatric clinical data for 25 molecularly-targeted and 4 biologic anticancer therapeutics. Other publications that evaluated the value of JAS in pediatric drug development focus on differences in toxicity between juvenile animals and adult animals. The present paper examines pediatric-specific clinical findings to focus on dose setting in pediatric oncology patients and safety monitoring in terms of the potential value of JAS. Our assessment demonstrates that pediatric starting doses were safe for all 29 therapeutics examined in that no life-threatening toxicities occurred in the first cohort, and overall the ratio of the pediatric maximum tolerated dose (MTD) to the recommended adult dose was close to 1. In addition, the 4 serious adverse events (SAEs) that weren't detectable with standard monitoring plans for pediatric oncology trials would not have been detectable in a standard JAS. This review demonstrates that safe starting doses in pediatric oncology patients for these therapeutics could have been solely based on adult doses without any knowledge of findings in JAS.

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.

Pharmacodynamic and Pharmacokinetic Markers For Anti-angiogenic Cancer Therapy: Implications for Dosing and Selection of Patients

Angiogenesis is integral to tumour growth and invasion, and is a key target for cancer therapeutics. However, for many of the licensed indications, only a modest clinical benefit has been observed for both monoclonal antibody and small-molecule tyrosine kinase inhibitor anti-angiogenic therapy. Pre-clinical and clinical studies have attempted to evaluate circulating, imaging, genomic, pharmacokinetic, and pharmacodynamic markers that may aid both the selection of patients for treatment and define dosing. Correct dosing is likely to be critical in the context of vascular normalization to allow better delivery of concomitant anti-cancer therapy and novel imaging techniques hold much promise in the early evaluation of pharmacodynamic response to improve efficacy.

Vamorolone, a dissociative steroidal compound, reduces pro-inflammatory cytokine expression in glioma cells and increases activity and survival in a murine model of cortical tumor

Corticosteroids, such as dexamethasone, are routinely used as palliative care in neuro-oncology for their anti-inflammatory benefits, however many patients experience dose limiting side effects caused by glucocorticoid response element (GRE)-mediated transcription. The purpose of this study was to use a murine model to investigate a new steroid alternative, vamorolone, which promises to reduce side effects through dissociating GRE-mediated transcription and NF-κB -mediated anti-inflammatory actions. To compare vamorolone to dexamethasone in reducing pro-inflammatory signals in vitro, murine glioma cells were treated with dexamethasone, vamorolone or vehicle control. Changes in mRNA expression were assessed using the nanostring inflammatory platform. Furthermore, drug efficacy, post-treatment behavioral activity and side effects were assessed by treating two cohorts of brain tumor bearing mice with dexamethasone, vamorolone, or vehicle control. Our investigation showed that treatment with vamorolone resulted in a reduction of pro-inflammatory signals in tumor cells in vitro similar to treatment with dexamethasone. Treatment with vamorolone resulted in a better safety profile in comparison to dexamethasone treatment. Vamorolone- treated mice showed similar or better activity and survival when compared to dexamethasone-treated mice. Our data indicate vamorolone is a potential steroid-sparing alternative for treating patients with brain tumors.

Neurological complications of new chemotherapy agents

This last decade has yielded more robust development of cancer treatments and first-in-class agents than ever before. Since 2006, nearly one hundred new drugs have received regulatory approval for the treatment of hematological and solid organ neoplasms. Moreover, older conventional therapies have received approval for new clinical indications and are being used in combination with these newer small-molecule targeted treatments. The nervous system is vulnerable to many of the traditional cancer therapies, manifesting both already well-described acute and chronic toxicities. However, newer agents may produce toxicities that may seem indistinguishable from the underlying cancer. Early recognition of neurotoxicities from new therapeutics is vital to avoid irreversible neurological injury. This review focuses on cancer therapies in use in the last 10 years and approved by the FDA from January 2006 through January 1, 2017.

Incidence, Diagnosis, and Management of QT Prolongation Induced by Cancer Therapies: A Systematic Review

Background

The cardiovascular complications of cancer therapeutics are the focus of the burgeoning field of cardio‐oncology. A common challenge in this field is the impact of cancer drugs on cardiac repolarization (ie, QT prolongation) and the potential risk for the life‐threatening arrhythmia torsades de pointes. Although QT prolongation is not a perfect marker of arrhythmia risk, this has become a primary safety metric among oncologists. Cardiologists caring for patients receiving cancer treatment should become familiar with the drugs associated with QT prolongation, its incidence, and appropriate management strategies to provide meaningful consultation in this complex clinical scenario.

Methods and Results

In this article, we performed a systematic review (using Preferred Reporting Items of Systematic Reviews and Meta‐Analyses (PRISMA) guidelines) of commonly used cancer drugs to determine the incidence of QT prolongation and clinically relevant arrhythmias. We calculated summary estimates of the incidence of all and clinically relevant QT prolongation as well as arrhythmias and sudden cardiac death. We then describe strategies to prevent, identify, and manage QT prolongation in patients receiving cancer therapy. We identified a total of 173 relevant publications. The weighted incidence of any corrected QT (QTc) prolongation in our systematic review in patients treated with conventional therapies (eg, anthracyclines) ranged from 0% to 22%, although QTc >500 ms, arrhythmias, or sudden cardiac death was extremely rare. The risk of QTc prolongation with targeted therapies (eg, small molecular tyrosine kinase inhibitors) ranged between 0% and 22.7% with severe prolongation (QTc >500 ms) reported in 0% to 5.2% of the patients. Arrhythmias and sudden cardiac death were rare.

Conclusions

Our systematic review demonstrates that there is variability in the incidence of QTc prolongation of various cancer drugs; however, the clinical consequence, as defined by arrhythmias or sudden cardiac death, remains rare.

Treatment-Related Noncontiguous Radiologic Changes in Children With Diffuse Intrinsic Pontine Glioma Treated With Expanded Irradiation Fields and Antiangiogenic Therapy

PURPOSE

We previously reported the cases of 3 children with diffuse intrinsic pontine glioma (DIPG) in whom noncontiguous treatment-related abnormalities (NCTRAs) developed in the brain after expanded-field radiation therapy (RT). To investigate the occurrence and putative mechanism of NCTRAs, we reviewed brain magnetic resonance imaging studies of patients with DIPG treated in 2 consecutive phase I clinical trials (trials 1 and 2).

METHODS AND MATERIALS

The 55 children included in these trials received small-molecule inhibitors: vandetanib in trial 1 (n=32; mean age 6.4 years) and vandetanib and dasatinib in trial 2 (n=23; mean age 5.8 years). The patients also received conformal 3-dimensional RT (cumulative dose 54 Gy). For patients enrolled in trial 1, the clinical target volume (CTV) was expanded by 1 cm from the gross tumor volume. In trial 2, the expansion to form the CTV was 2 to 3 cm. A review of imaging studies was performed from the initial diagnosis through the end of progression-free survival. The imaging findings were grouped into 5 categories according to the presence, absence, location, extent, and putative mechanism of NCTRAs. Statistical analysis was performed to evaluate the association between covariates and NCTRA, cohort characterization, and survival comparisons.

RESULTS

Overall survival was similar in both studies (P=.74). NCTRAs developed in 9 patients (39%) treated in trial 2 but in none treated in trial 1. The NCTRAs included T2-weighted hyperintensities with (n=3; radiation necrosis) or without (n=5) contrast uptake, supratentorial leukoencephalopathy (n=2), and ischemic stroke (n=1). All NCTRAs, except for 1, occurred within the CTV. Compared with nonaffected patients, patients with a NCTRA were younger (P=.003) and had had larger relative brain volumes exposed to doses >20 Gy.

CONCLUSIONS

The imaging features of NCTRAs suggest that their development is secondary to synergistic steno-occlusive vascular effects induced by the combination of RT, an expanded CTV, potent antiangiogenic therapy, young age, and, in 1 case, a genetic predisposition.

Developing chemotherapy for diffuse pontine intrinsic gliomas (DIPG)

Prognosis of diffuse intrinsic pontine glioma (DIPG) is poor, with a median survival of 10 months after radiation. At present, chemotherapy has failed to show benefits over radiation. Advances in biotechnology have enabled the use of autopsy specimens for genomic analyses and molecular profiling of DIPG, which are quite different from those of supratentorial high grade glioma. Recently, combined treatments of cytotoxic agents with target inhibitors, based on biopsied tissue, are being examined in on-going trials. Spontaneous DIPG mice models have been recently developed that is useful for preclinical studies. Finally, the convection-enhanced delivery could be used to infuse drugs directly into the brainstem parenchyma, to which conventional systemic administration fails to achieve effective concentration. The WHO glioma classification defines a diffuse midline glioma with a H3-K27M-mutation, and we expect increase of tissue confirmation of DIPG, which will give us the biological information helping the development of a targeted therapy.

Enhanced glioma therapy by synergistic inhibition of autophagy and tyrosine kinase activity

Autophagy is a lysosomal degradation pathway that acts as a cytoprotective mechanism causing treatment resistance in various cancer cells. Recent studies showed that hydroxychloroquine can inhibit the latter step of autophagy and therefore enhance the anti-glioma efficiency of ZD6474, a tyrosine kinase inhibitor. However, the nonselective distribution of ZD6474 in vivo and the low penetrating ability of hydroxychloroquine when crossing the blood-brain barrier restrict their clinical use in glioma therapy. Here we coencapsulated ZD6474 and hydroxychloroquine into R6dGR peptide-modified liposomes (R6dGR-Lip) which can specifically recognize both integrin αvβ3 and neuropilin-1 receptors that are highly expressed on the endothelial cells and glioma cells. R6dGR significantly enhanced the brain targeting and overcame the blood-brain barrier. Our results confirmed that loading hydroxychloroquine into R6dGR-Lip blocked autophagic flux more efficiently than free hydroxychloroquine in glioma cells and significantly sensitized glioma cells to ZD6474-induced cell death in vitro and in vivo. The coencapsulated R6dGR-modified liposomes (ZD6474/HCQ-R6dGR-Lip) prolonged the medium survival time of intracranial C6 glioma bearing mice by 1.2-fold compared with ZD6474-R6dGR-Lip, 1.5-fold compared with free ZD6474/HCQ, and 1.8-fold compared with free ZD6474, exhibiting a synergistic therapeutic effect. Therefore, ZD6474/HCQ-R6dGR-Lip is presented as a potential strategy which could be further used for efficient anti-glioma therapy.

Pediatric Patient With Renal Cell Carcinoma Treated by Successive Antiangiogenics Drugs: A Case Report and Review of the Literature

Antiangiogenic drugs are currently standard of care in adults with renal cell carcinoma (RCC), including translocation RCC. Although antitumor activity and toxicity profile are well known in adults, few data have been reported in children. Here we present the case of a patient diagnosed at 2 years old with a metastatic translocation RCC, consecutively treated with 5 tyrosine kinase inhibitors during 6 years. The antitumor activity and toxic effects are described, and a brief review of the literature is presented.

Measurable Supratentorial White Matter Volume Changes in Patients with Diffuse Intrinsic Pontine Glioma Treated with an Anti-Vascular Endothelial Growth Factor Agent, Steroids, and Radiation

BACKGROUND AND PURPOSE

Assessing the response to treatment in infiltrative brain tumors by using lesion volume-based response criteria is challenging. We hypothesized that in such tumors, volume measurements alone may not accurately capture changes in actual tumor burden during treatment. We longitudinally evaluated volume changes in both normal-appearing supratentorial white matter and the brain stem lesions in patients treated for diffuse intrinsic pontine glioma to determine to what extent adjuvant systemic therapies may skew the accuracy of tumor response assessments based on volumetric analysis.

MATERIALS AND METHODS

The anatomic MR imaging and diffusion tensor imaging data of 26 patients with diffuse intrinsic pontine glioma were retrospectively analyzed. Treatment included conformal radiation therapy in conjunction with vandetanib and dexamethasone. Volumetric and diffusion data were analyzed with time, and differences between time points were evaluated statistically.

RESULTS

Normalized brain stem lesion volume decreased during combined treatment (slope = -0.222, P < .001) and increased shortly after completion of radiation therapy (slope = 0.422, P < .001). Supratentorial white matter volume steadily and significantly decreased with time (slope = -0.057, P < .001).

CONCLUSIONS

Longitudinal changes in brain stem lesion volume are robust; less pronounced but measurable changes occur in the supratentorial white matter. Volume changes in nonirradiated supratentorial white matter during the disease course reflect the effects of systemic medication on the water homeostasis of normal parenchyma. Our data suggest that adjuvant nontumor-targeted therapies may have a more substantial effect on lesion volume changes than previously thought; hence, an apparent volume decrease in infiltrative tumors receiving combined therapies may lead to overestimation of the actual response and tumor control.

MRI Evaluation of Non-Necrotic T2-Hyperintense Foci in Pediatric Diffuse Intrinsic Pontine Glioma

BACKGROUND AND PURPOSE

The conventional MR imaging appearance of diffuse intrinsic pontine glioma suggests intralesional histopathologic heterogeneity, and various distinct lesion components, including T2-hypointense foci, have been described. Here we report the prevalence, conventional MR imaging semiology, and advanced MR imaging features of non-necrotic T2-hyperintense foci in diffuse intrinsic pontine glioma.

MATERIALS AND METHODS

Twenty-five patients with diffuse intrinsic pontine gliomas were included in this study. MR imaging was performed at 3T by using conventional and advanced MR imaging sequences. Perfusion (CBV), vascular permeability (v_e, K^trans), and diffusion (ADC) metrics were calculated and used to characterize non-necrotic T2-hyperintense foci in comparison with other lesion components, namely necrotic T2-hyperintense foci, T2-hypointense foci, peritumoral edema, and normal brain stem. Statistical analysis was performed by using Kruskal-Wallis and Wilcoxon rank sum tests.

RESULTS

Sixteen non-necrotic T2-hyperintense foci were found in 12 tumors. In these foci, ADC values were significantly higher than those in either T2-hypointense foci (P = .002) or normal parenchyma (P = .0002), and relative CBV values were significantly lower than those in either T2-hypointense (P = .0002) or necrotic T2-hyperintense (P = .006) foci. Volume transfer coefficient values in T2-hyperintense foci were lower than those in T2-hypointense (P = .0005) or necrotic T2-hyperintense (P = .0348) foci.

CONCLUSIONS

Non-necrotic T2-hyperintense foci are common, distinct lesion components within diffuse intrinsic pontine gliomas. Advanced MR imaging data suggest low cellularity and an early stage of angioneogenesis with leaky vessels resulting in expansion of the extracellular space. Because of the lack of biopsy validation, the underlying histoarchitectural and pathophysiologic changes remain unclear; therefore, these foci may correspond to a poorly understood biologic event in tumor evolution.

Brainstem Glioma in Adults

Brainstem gliomas are not nearly as common in adults as they are in children. They are likely the final common consequence not of a single disease process but of several. They can be difficult to diagnose, and are challenging to treat. Clinical studies of this diagnosis are few and generally small. Because of these factors, our understanding of the biology of adult brainstem glioma is incomplete. However, the knowledge base is growing and progress is being made. In this article, we review the current state of knowledge for brainstem glioma in adults and identify key areas for which additional information is required.

Discrepant longitudinal volumetric and metabolic evolution of diffuse intrinsic Pontine gliomas during treatment: implications for current response assessment strategies

INTRODUCTION

Based on clinical observations, we hypothesized that in infiltrative high-grade brainstem neoplasms, such as diffuse intrinsic pontine glioma (DIPG), longitudinal metabolic evaluation of the tumor by magnetic resonance spectroscopy (MRS) may be more accurate than volumetric data for monitoring the tumor's biological evolution during standard treatment.

METHODS

We evaluated longitudinal MRS data and corresponding tumor volumes of 31 children with DIPG. We statistically analyzed correlations between tumor volume and ratios of Cho/NAA, Cho/Cr, and NAA/Cr at key time points during the course of the disease through the end of the progression-free survival period.

RESULTS

By the end of RT, tumor volume had significantly decreased from the baseline (P < .0001) and remained decreased through the last available follow-up magnetic resonance imaging study (P = .007632). However, the metabolic profile of the tumor tissue (Cho/Cr, NAA/Cr, and Cho/NAA ratios) did not change significantly over time.

CONCLUSION

Our data show that longitudinal tumor volume and metabolic profile changes are dissociated in patients with DIPG during progression-free survival. Volume changes, therefore, may not accurately reflect treatment-related changes in tumor burden. This study adds to the existing body of evidence that the value of conventional MRI metrics, including volumetric data, needs to be reevaluated critically and, in infiltrative tumors in particular, may not be useful as study end-points in clinical trials. We submit that advanced quantitative MRI data, including robust, MRS-based metabolic ratios and diffusion and perfusion metrics, may be better surrogate markers of key end-points in clinical trials.

State of affairs in use of steroids in diffuse intrinsic pontine glioma: an international survey and a review of the literature

Children diagnosed with diffuse intrinsic pontine glioma (DIPG) face a dismal prognosis, with severe neurologic deterioration and inevitable death at a median of 9 months from diagnosis. Steroids are widely prescribed as supportive or palliative treatment although they are known to cause severe side effects that may reduce the quality of life. This study aims to review the current knowledge on, and use of, steroids in DIPG patients. A global questionnaire-study among health care professionals was performed to ascertain information on the current (multi-)institutional and (multi-)national use of steroids, the availability of clinical guidelines, and the need for improvements in prescribing steroids to DIPG patients. In addition, an extensive literature search was performed to review studies investigating steroids in pediatric brain tumor patients. From 150 responding health care professionals, only 7 % had clinical guidelines. The use of steroids was heterogeneous and over 85 % of respondents reported serious side effects. Fourteen articles, with low level of evidence, described the use of steroids in pediatric brain tumor patients. Clinical trials investigating optimal dose or regimen were lacking. This study is a first inventory of the availability of evidence-based information and clinical guidelines, and the current attitude towards the use of steroids in DIPG patients. To date, the risk–benefit ratio of steroids in this disease is yet to be determined. We emphasize the need for clinical trials resulting in guidelines on steroids, and possibly alternative drugs, to optimize the quality of care and quality of life of DIPG patients.

DIPG in Children - What Can We Learn from the Past?

Brainstem tumors represent 10–15% of pediatric central nervous system tumors and diffuse intrinsic pontine glioma (DIPG) is the most common brainstem tumor of childhood. DIPG is almost uniformly fatal and is the leading cause of brain tumor-related death in children. To date, radiation therapy (RT) is the only form of treatment that offers a transient benefit in DIPG. Chemotherapeutic strategies including multi-agent neoadjuvant chemotherapy, concurrent chemotherapy with RT, and adjuvant chemotherapy have not provided any survival advantage. To overcome the restrictive ability of the intact blood–brain barrier (BBB) in DIPG, several alternative drug delivery strategies have been proposed but have met with minimal success. Targeted therapies either alone or in combination with RT have also not improved survival. Five decades of unsuccessful therapies coupled with recent advances in the genetics and biology of DIPG have taught us several important lessons (1). DIPG is a heterogeneous group of tumors that are biologically distinct from other pediatric and adult high grade gliomas (HGG). Adapting chemotherapy and targeted therapies that are used in pediatric or adult HGG for the treatment of DIPG should be abandoned (2). Biopsy of DIPG is relatively safe and informative and should be considered in the context of multicenter clinical trials (3). DIPG probably represents a whole brain disease so regular neuraxis imaging is important at diagnosis and during therapy (4). BBB permeability is of major concern in DIPG and overcoming this barrier may ensure that drugs reach the tumor (5). Recent development of DIPG tumor models should help us accurately identify and validate therapeutic targets and small molecule inhibitors in the treatment of this deadly tumor.

Diffuse intrinsic pontine glioma: time for therapeutic optimism

Diffuse intrinsic pontine glioma (DIPG) is an aggressive tumor that is universally fatal, and to-date we are at a virtual standstill in improving its grim prognosis. Dearth of tissue due to rarity of biopsy has precluded understanding the elusive biology and frustration continues in reproducing faithful animal models for translational research. Furthermore the intricate anatomy of the pons has forestalled locoregional therapy and drug penetration. Over the last few years, biopsy-driven targeted therapy, development of vitro and xenograft animal models for therapeutic testing, profiling immunotherapeutic strategies and locoregional infusion of drugs in brain stem tumors, now provide a sense of hope in the years ahead. This review aims to discuss current status and advances in the management of these tumors.

Diffuse intrinsic pontine gliomas: treatments and controversies

Diffuse intrinsic pontine gliomas (DIPGs) are a fairly common pediatric brain tumor, and children with these tumors have a dismal prognosis. They generally are diagnosed within the first decade of life, and due to their location within the pons, these tumors are not surgically resectable. The median survival for children with DIPGs is less than 1 year, in spite of decades of clinical trial development of unique approaches to radiation therapy and chemotherapy. Novel therapies are under investigation for these deadly tumors. As clinicians and researchers make a concerted effort to obtain tumor tissue, the molecular signals of these tumors are being investigated in an attempt to uncover targetable therapies for DIPGs. In addition, direct application of chemotherapies into the tumor (convection-enhanced delivery) is being investigated as a novel delivery system for treatment of DIPGs. Overall, DIPGs require creative thinking and a disciplined approach for development of a therapy that can improve the prognosis for these unfortunate children.

Pediatric diffuse intrinsic pontine glioma: can optimism replace pessimism?

Pediatric diffuse intrinsic pontine glioma (DIPG) has a dismal prognosis that has not seen a change in outcome despite multiple clinical trials. Possible reasons for failure to make progress in this aggressive childhood brain tumor include: poor understanding of the underlying molecular biology due to lack of access to tumor material; absence of accurate and relevant DIPG preclinical models for drug development; ill-defined therapeutic targets for novel agents; and inadequate drug delivery to the brainstem. This review will demonstrate that systematic studies to identify solutions for each of these barriers is starting to deliver progress that can turn pessimism to optimism in DIPG.

Receptor tyrosine kinase inhibitors: Are they real tumor killers?

Inhibiting tumor growth by targeting the tumor vasculature was first proposed by Judah Folkman almost 40 years ago. Since then, different approaches and numerous drugs and agents have been developed to achieve this goal, either with the aim of inhibiting tumor neoangiogenesis or normalizing the tumor vasculature. Among the most promising therapeutic targets are receptor tyrosine kinases (RTKs), some of which are predominantly expressed on tumor endothelial cells, although they are sometimes also present on tumor cells. The majority of RTK inhibitors investigated over the past two decades competes with ATP at the active site of the kinase and therefore block the phosphorylation of intracellular targets. Some of these drugs have been approved for therapy, whereas others are still in clinical trials. Here, we discuss the scientific basis, current status, problems and future prospects of RTK inhibition in anti-tumor therapy.

Translating genomic discoveries to the clinic in pediatric oncology

PURPOSE OF REVIEW

The present study describes the recent advances in the identification of targetable genomic alterations in pediatric cancers, along with the progress and associated challenges in translating these findings into therapeutic benefit.

RECENT FINDINGS

Each field within pediatric cancer has rapidly and comprehensively begun to define genomic targets in tumors that potentially can improve the clinical outcome of patients, including hematologic malignancies (leukemia and lymphoma), solid malignancies (neuroblastoma, rhabdomyosarcoma, Ewing sarcoma, and osteosarcoma), and brain tumors (gliomas, ependymomas, and medulloblastomas). Although each tumor has specific and sometimes overlapping genomic targets, the translation to the clinic of new targeted trials and precision medicine protocols is still in its infancy. The first clinical tumor profiling studies in pediatric oncology have demonstrated feasibility and patient enthusiasm for the personalized medicine paradigm, but have yet to demonstrate clinical utility. Complexities influencing implementation include rapidly evolving sequencing technologies, tumor heterogeneity, and lack of access to targeted therapies. The return of incidental findings from the germline also remains a challenge, with evolving policy statements and accepted standards.

SUMMARY

The translation of genomic discoveries to the clinic in pediatric oncology continues to move forward at a brisk pace. Early adoption of genomics for tumor classification, risk stratification, and initial trials of targeted therapeutic agents has led to powerful results. As our experience grows in the integration of genomic and clinical medicine, the outcome for children with cancer should continue to improve.

Primary brain tumors and posterior reversible encephalopathy syndrome

BACKGROUND

Posterior reversible encephalopathy syndrome (PRES) is a neurotoxic encephalopathic state associated with reversible cerebral vasogenic edema. It is an increasingly recognized occurrence in the oncology population. However, it is very uncommon in patients with primary brain tumors (PBTs). The aim of this study was to analyze the clinicoradiological features and report the clinical outcomes of PRES in PBT patients.

METHODS

We identified 4 cases with PBT who developed PRES at MD Anderson Cancer Center (MDACC) between 2012 and 2014. Clinical and radiological data were abstracted from their records. In addition, we also solicited 8 cases from the literature.

RESULTS

The median age at PRES onset was 19 years, male-to-female ratio was 1:1, and the syndrome occurred in patients with ependymoma (n = 4), glioblastoma (n = 3), diffuse intrinsic pontine glioma (DIPG; n = 3), juvenile pilocytic astrocytoma (n = 1), and atypical meningioma (n = 1). Two glioblastomas and 2 DIPG cases received bevacizumab and vandetanib before the onset of symptoms, respectively. The most common clinical presentation was seizures (n = 7). Three MDACC patients recovered completely in 3-4 weeks after the onset of symptoms. One patient died due to active cancer and several comorbidities including PRES.

CONCLUSIONS

Hypertension seems to be the most important coexisting risk factor for development of PRES; however, the potential effects of chemotherapeutic agents in the pathogenesis of PRES should also be examined. The clinicoradiological course of PRES in PBT patients did not vary from the classical descriptions of PRES found in other causes. PRES must be considered as part of the differential diagnosis in patients with PBTs presenting with seizures or acute encephalopathy.

Effect of time from diagnosis to start of radiotherapy on children with diffuse intrinsic pontine glioma

BACKGROUND

Children with diffuse intrinsic pontine glioma (DIPG) continue to have poor outcomes, and radiotherapy (RT) is the only temporarily effective treatment. In this retrospective analysis, we studied the effect of time from diagnosis to start of RT on event-free survival (EFS) and overall survival (OS) in children with DIPG.

METHODS

Records of children (n = 95) with DIPG treated with RT at a single institution between April 1999 and September 2009 were analyzed. RT was delivered at doses of 54.0-55.8 Gy at 1.8 Gy per fraction, and children were followed prospectively. The effect of gender, race, interruption during treatment course, age at diagnosis, duration of symptoms prior to diagnosis, use of protocol-based chemotherapy, and time from diagnosis to initiation of RT on EFS and OS was assessed by the Cox proportional hazards model.

RESULTS

Time as a continuous variable from diagnosis to start of RT did not affect outcome. Time dichotomized to ≤14 days significantly affected OS (hazard ratio [HR] = 1.70, P = 0.014) and race other than white or black affected EFS (HR = 2.32, P = 0.017). The 95 patients had a 6-month EFS and OS of 60 ± 5% and 94.7 ± 2.3%, respectively, and a 12-month EFS and OS of 11.6 ± 3.1% and 49.5 ± 5%, respectively.

CONCLUSIONS

Time as a continuous variable did not affect OS or EFS in our cohort; however, children treated within 2 weeks of diagnosis had poor outcomes. Although rapid initiation of RT is desirable, our findings do not support intensive efforts aimed at shortening delays from diagnosis to start of RT.

Molecular profiling of childhood cancer: Biomarkers and novel therapies

BACKGROUND

Technological advances including high-throughput sequencing have identified numerous tumor-specific genetic changes in pediatric and adolescent cancers that can be exploited as targets for novel therapies.

SCOPE OF REVIEW

This review provides a detailed overview of recent advances in the application of target-specific therapies for childhood cancers, either as single agents or in combination with other therapies. The review summarizes preclinical evidence on which clinical trials are based, early phase clinical trial results, and the incorporation of predictive biomarkers into clinical practice, according to cancer type.

MAJOR CONCLUSIONS

There is growing evidence that molecularly targeted therapies can valuably add to the arsenal available for treating childhood cancers, particularly when used in combination with other therapies. Nonetheless the introduction of molecularly targeted agents into practice remains challenging, due to the use of unselected populations in some clinical trials, inadequate methods to evaluate efficacy, and the need for improved preclinical models to both evaluate dosing and safety of combination therapies.

GENERAL SIGNIFICANCE

The increasing recognition of the heterogeneity of molecular causes of cancer favors the continued development of molecularly targeted agents, and their transfer to pediatric and adolescent populations.

Phase 2 study of safety and efficacy of nimotuzumab in pediatric patients with progressive diffuse intrinsic pontine glioma

BACKGROUND

The prognosis of diffuse intrinsic pontine glioma (DIPG) remains poor, with no drug proven to be effective.

METHODS

Patients with clinically and radiologically confirmed, centrally reviewed DIPG, who had failed standard first-line therapy were eligible for this multicenter phase II trial. The anti-epidermal growth factor receptor (EGFR) antibody, nimotuzumab (150 mg/m(2)), was administered intravenously once weekly from weeks 1 to 7 and once every 2 weeks from weeks 8 to 18. Response evaluation was based on clinical and MRI assessments. Patients with partial response (PR) or stable disease (SD) were allowed to continue nimotuzumab.

RESULTS

Forty-four patients received at least one dose of nimotuzumab (male/female, 20/24; median age, 6.0 years; range, 3.0-17.0 years). All had received prior radiotherapy. Treatment was well tolerated. Eighteen children experienced serious adverse events (SAEs). The majority of SAEs were associated with disease progression. Nineteen patients completed 8 weeks (W8) of treatment: There were 2 PRs, 6 SDs, and 11 progressions. Five patients completed 18 weeks (W18) of treatment: 1 of 2 patients with PR at W8 remained in PR at W18, and 3 of 6 children with SD at W8 maintained SD at W18. Time to progression following initiation of nimotuzumab for the 4 patients with SD or better at W18 was 119, 157, 182 and 335 days, respectively. Median survival time was 3.2 months. Two patients lived 663 and 481 days from the start of nimotuzumab.

CONCLUSIONS

Modest activity of nimotuzumab in DIPG, which has been shown previously, was confirmed: A small subset of DIPG patients appeared to benefit from anti-EGFR antibody treatment.