Abstract
BRAF kinase mutations and duplications are among the most common genetic alterations seen in pediatric low-grade gliomas. The BRAF V600E mutation is a missense mutation involving an amino ...acid substitution at position 600 in BRAF, from valine to glutamic acid, leading to constitutive activation of the MAPK pathway. Dabrafenib, a selective BRAF inhibitor, has demonstrated clinical efficacy in BRAF V600E-positive low-grade gliomas in early phase testing. While dabrafenib is typically used as a second-line agent in low-grade glioma, its efficacy, minimal toxicity, and ease of administration make the drug an attractive candidate for first-line use. We present two patients with BRAF V600E-postitive low-grade gliomas who received respective late and early dabrafenib therapy. The first is a patient with a glioneuronal tumor involving the brain and spine. Over nine years, her symptoms progressed to include paraplegia despite surgical resection, multiple chemotherapy regimens, and radiotherapy. Following her most recent progression, her tumor was re-examined and found to express the BRAF V600E mutation. She received dabrafenib with subsequent resolution of her brain lesion and significant improvement in her spine disease. The second patient presented with left-sided weakness and a visual field deficit and underwent a partial resection of a right thalamic BRAF V600E-positive ganglioglioma. She began first-line therapy with dabrafenib with subsequent neurologic improvement and a decrease in T2 hyperintensity and resolution of tumor enhancement on MRI. These contrasting cases highlight the need to consider early dabrafenib therapy in patients with high-risk BRAF V600E-positive tumors as a means to prevent further neurologic injury.
Background
High‐grade gliomas (HGG) have a dismal prognosis despite multimodal therapy. Mebendazole is an anti‐helminthic benzimidazole that has demonstrated efficacy in numerous in vitro cancer ...models, and is able to cross the blood–brain barrier. We conducted a phase 1 trial (NCT01837862) to evaluate the safety of mebendazole in combination with bevacizumab and irinotecan in children and young adults with HGG.
Objective
To determine the maximally tolerated dose of mebendazole when given in combination with bevacizumab and irinotecan in children with HGG; to describe the progression‐free survival (PFS) and overall survival (OS) for this group.
Design/method
Patients between 1 and 21 years of age with HGG were enrolled in a 3 + 3 design to escalating doses of mebendazole in combination with bevacizumab (10 mg/kg/dose) and irinotecan (150 mg/m2/dose). Subjects were eligible upfront after completion of radiation or at the time of progression. Mebendazole was taken orally twice per day continuously, and bevacizumab and irinotecan were given intravenously on Days 1 and 15 of 28‐day cycles.
Results
Between 2015 and 2020, 10 subjects were enrolled at mebendazole doses of 50 mg/kg/day (n = 3), 100 mg/kg/day (n = 4), and 200 mg/kg/day (n = 3). One subject assigned to 100 mg/kg/day was not evaluable. Seven subjects had a diagnosis of diffuse midline glioma, one subject had anaplastic astrocytoma, and one subject had a spinal HGG. All subjects received radiation. There were no dose‐limiting toxicities. The most frequent G3/4 adverse events were neutropenia (n = 3) and lymphopenia (n = 4). The overall response rate was 33%, with two subjects achieving a partial response and one subject achieving a complete response sustained for 10 months. The mean PFS and OS from the start of study treatment were 4.7 and 11.4 months, respectively.
Conclusion
Mebendazole was safe and well tolerated when administered with bevacizumab and irinotecan at doses up to 200 mg/kg/day. Further studies are needed to determine the efficacy of this treatment.
Abstract
INTRODUCTION
Rhabdoid tumors (RTs) are highly aggressive malignancies caused by a loss–of–function mutation in the SMARCB1 tumor suppressor gene on chromosome 22 that makes up the SW1/SNF ...chromatin remodeling complex involved in gene transcription. In rhabdoid tumor predisposition syndrome (RTPS), a biallelic germline SMARCB1 mutation markedly increases the risk of affected individuals developing early, aggressive, and rapidly progressing RTs, most commonly in the CNS, referred to as atypical teratoid rhabdoid tumors (AT/RT), and the kidneys, but oftentimes presents with synchronous lesions. In this case series, we present a family affected by RTPS with a recurrence of AT/RT in two infant siblings with the same germline SMARCB1 mutation.
CASE SERIES DESCRIPTION
An 8-month-old female was brought to the emergency department for 3 months of vomiting, developmental regression, and CN VI palsy. Brain imaging revealed a posterior fossa mass, acquired obstructive hydrocephalus, and spinal metastasis. Four years later, her 3-month-old sister was also brought in for evaluation for 2 months of vomiting, irritability, increasing head circumference, and vertical gaze palsy. Her brain imaging similarly showed a posterior fossa mass and acquired obstructive hydrocephalus, but no metastasis. Both siblings underwent subtotal tumor resections and ventriculoperitoneal shunt placement followed by chemotherapy. While on active treatment, they experienced rapid disease progression and ultimately succumbed to their illness. Genetic testing on the family identified the same in-frame deletion in the SNF5 homology domain of SMARCB1 and loss of heterozygosity of chromosome 22 in the two sisters; their mother was found to be a carrier.
CONCLUSION
This case series describes a family affected by RTPS, demonstrating the risk of familial recurrence in SMARCB1 germline mutations and emphasizing the need for genetic testing and counseling for these families should they wish to have additional children.
Abstract
BACKGROUND
Embryonal tumor with multilayered rosettes (ETMR) is a deadly pediatric brain tumor with limited available therapeutic options. Dysregulated mitochondrial bioenergetics and ...dynamics have been linked to the initiation and progression of diverse human cancers, however, their role in ETMR pathobiology remains unknown. We used the primary ETMR cell line, BT183, and an in-house developed human neural stem cell (NSC) line to evaluate mitochondrial morphology, bioenergetics and fission-fusion dynamics involved in ETMR growth and aggression.
METHODS
Mitochondrial morphology was determined by widefield immunofluorescence and dSTORM super-resolution microscopy in BT183 and NSC monolayers and by TEM in BT183 and NSCs grown as neurospheres. Relative expression of mitochondrial proteins were quantified in BT183 and NSC lysates by western blotting.
RESULTS
Widefield immunofluorescence and super-resolution imaging revealed profound differences in mitochondrial morphology in BT183 compared to NSCs. BT183 mitochondria appear as fragmented, rounded structures, with little interconnectivity, while NSC mitochondria present a typical elongated, filamentous morphology. These findings were corroborated by TEM image analysis of BT183 and NSC neurospheres, which revealed additional morphological alterations in BT183 mitochondria at the ultrastructural level, including aberrant cristae structure. Western blot analysis of BT183 and NSC lysates showed up to 5-fold differential expression of mitochondrial OXPHOS, glycolytic and fission-fusion proteins in the two cell types. Fission promoters phospho-Drp1 and MFF displayed significantly higher expression in BT183 relative to NSCs, whereas fusion-inducing proteins Opa1 and Miro2 showed significantly lower differential expression in BT183.
CONCLUSIONS
BT183 cells exhibited striking mitochondrial fragmentation and differential expression of proteins involved in fission-fusion, OXPHOS and glycolysis when compared to normal human NSCs. Ongoing studies include the analysis of mitochondrial structure and morphology in patient samples to validate our in-vitro findings, in addition to in-vitro metabolic flux analysis and targeted protein depletion studies to identify druggable pathways based on mitochondrial function and dynamics.
Abstract
BACKGROUND
Embryonal tumor with multilayered rosettes (ETMR) is a deadly pediatric brain tumor with limited available therapeutic options. Dysregulated mitochondrial bioenergetics and ...dynamics have been linked to the initiation and progression of diverse human cancers, however, their role in ETMR pathobiology remains unknown. We used the primary ETMR cell line, BT183, and an in-house developed human neural stem cell (NSC) line to evaluate mitochondrial morphology, bioenergetics and fission-fusion dynamics involved in ETMR growth and aggression.
METHODS
Mitochondrial morphology was determined by widefield immunofluorescence and dSTORM super-resolution microscopy in BT183 and NSC monolayers and by TEM in BT183 and NSCs grown as neurospheres. Relative expression of mitochondrial proteins were quantified in BT183 and NSC lysates by western blotting.
RESULTS
Widefield immunofluorescence and super-resolution imaging revealed profound differences in mitochondrial morphology in BT183 compared to NSCs. BT183 mitochondria appear as fragmented, rounded structures, with little interconnectivity, while NSC mitochondria present a typical elongated, filamentous morphology. These findings were corroborated by TEM image analysis of BT183 and NSC neurospheres, which revealed additional morphological alterations in BT183 mitochondria at the ultrastructural level, including aberrant cristae structure. Western blot analysis of BT183 and NSC lysates showed up to 5-fold differential expression of mitochondrial OXPHOS, glycolytic and fission-fusion proteins in the two cell types. Fission promoters phospho-Drp1 and MFF displayed significantly higher expression in BT183 relative to NSCs, whereas fusion-inducing proteins Opa1 and Miro2 showed significantly lower differential expression in BT183.
CONCLUSIONS
BT183 cells exhibited striking mitochondrial fragmentation and differential expression of proteins involved in fission-fusion, OXPHOS and glycolysis when compared to normal human NSCs. Ongoing studies include the analysis of mitochondrial structure and morphology in patient samples to validate our in-vitro findings, in addition to in-vitro metabolic flux analysis and targeted protein depletion studies to identify druggable pathways based on mitochondrial function and dynamics.
Abstract
BACKGROUND: High grade gliomas (HGG) have a dismal prognosis despite multimodal therapy. Mebendazole (MBZ) is an anti-helminthic benzimidazole. In vitro, MBZ has efficacy in numerous cancer ...models and is able to cross the blood brain barrier. We conducted a phase 1 trial (NCT01837862) to evaluate the safety of MBZ in combination with bevacizumab (BVCZ) and irinotecan (CPT-11). OBJECTIVE: To determine the maximally tolerated dose of MBZ when given in combination with BVCZ and CPT-11 in children with high-grade gliomas; to describe the progression-free survival (PFS) and overall survival (OS) for this group. METHODS: Patients between 1 and 21 years of age with HGG were enrolled in a 3 + 3 design to escalating doses of MBZ in combination with BVCZ 10mg/kg/dose and CPT-11 150mg/m2/dose. Subjects were eligible upfront after completion of radiation or at the time of progression. MBZ was taken orally twice per day continuously and BVCZ and CPT-11 were given intravenously on days 1 and 15 of 28-day cycles. RESULTS: Between 2015 and 2020, 10 subjects were enrolled at MBZ 50mg/kg/day (n=3), 100mg/kg/day (n=4), and 200mg/kg/day (n=3). One subject assigned to 100mg/kg/day was not evaluable. Seven subjects had a diagnosis of diffuse midline glioma, 1 subject had anaplastic astrocytoma, and 1 subject had a spinal HGG. All subjects received radiation. There were no dose limiting toxicities. The most frequent G3/G4 adverse events were neutropenia (n=3), and lymphopenia (n= 4). The overall response rate was 33% with 2 subjects achieving a partial response and 1 subject achieving a complete response sustained for 10 months. The PFS and OS from the start of study treatment were 4.7 months and 11.4 months, respectively. CONCLUSION: MBZ was safe and well tolerated when administered with BVCZ and CPT-11 at doses up to 200mg/kg/day. Further studies are needed to determine the efficacy of this treatment.
Abstract Embryonal tumor with multilayered rosettes (ETMR) is a highly aggressive CNS neoplasm that occurs almost exclusively in infants and is associated with an extremely poor prognosis. ...Dysregulated mitochondrial bioenergetics and dynamics have been associated with the initiation and progression of diverse cancers and studies have linked metabolic rewiring to chemotherapy resistance. Cardiolipins are mitochondrial-specific lipids that reside in the mitochondrial membrane and their fatty acid composition has been extensively shown to regulate mitochondrial function and dynamics. Despite the known functional significance of cardiolipin structure, their role in mitochondrial regulation of brain tumors remains ill-defined. Using mass spectrometry imaging, we identified a shift to shorter acyl chain cardiolipins within the rapidly proliferating embryonal tumor cells in patient samples and patient-derived cell lines grown as 3D tumorspheres. Western blot analysis of the enzymes involved in cardiolipin synthesis and remodeling identified a significant increase in the expression of the cardiolipin remodeling enzyme, LCLAT1/ALCAT1. Orthogonal imaging techniques including immunohistochemistry, transmission electron microscopy and super-resolution microscopy correlated shorter acyl chain remodeling of cardiolipin with fragmented mitochondria (increased fission) and aberrant cristae structure. Further studies identified increased expression of the fission protein Drp1, decreased expression of respiratory chain enzymes and altered respiration in the embryonal tumor cells. Ongoing studies will utilize multiple methods to modulate cardiolipin acyl chain structure and use MS and MSI to correlate cardiolipin fatty acid structure to mitochondrial function and growth inhibition in the embryonal tumor cells.
Abstract
Embryonal tumor with multilayer rosettes (ETMR) is a rare and highly-aggressive CNS neoplasm which occurs almost exclusively in young children and is associated with an extremely poor ...prognosis. The tumor is characterized by the presence of C19MC amplification in the majority of cases and all specimens demonstrate overexpression of LIN28. To date no large clinical investigations have been conducted to determine the optimal therapy for these tumors and patients have been treated according to a variety of regimens. Historical data suggests that extensive surgical resection, radiotherapy, and high-dose chemotherapy are not sufficient treatment in the vast majority of cases. As such, it is imperative that the known biology of these tumors be taken into consideration and that additional therapies targeting underlying oncogenic mechanisms in ETMR are incorporated into any investigational regimen. The Dana-Farber modified IRS-III protocol has demonstrated success in the treatment of children with atypical teratoid rhabdoid tumor. This regimen includes many agents found to be effective in the recent German drug screen using the ETMR BT183 cell line, including doxorubicin and actinomycin D. To date, four children with ETMR have been treated with IRS-III chemotherapy, three of which have progression-free survival of >2 years. Based on these encouraging outcomes, a phase II multi-center study with an IRS-III-based consensus therapy approach is proposed. In addition, an international registry of children diagnosed with ETMR has been formed. The goals of the registry include obtaining survival data for this rare population, evaluating therapeutic response to the consensus therapy and procuring patient tumor tissue for use in preclinical modeling to further develop new biology-based therapies. Difluoromethylornithine (DFMO) as a biologic maintenance agent targeting the LIN28/let-7 axis is also being developed and will be available to registry participants at the completion of their up-front therapy.
Abstract
Embryonal tumor with multilayered rosettes (ETMR) is a highly aggressive CNS neoplasm that occurs almost exclusively in infants under 4 years of age and is associated with an extremely poor ...prognosis. A bottleneck in the development of new and curative treatments for ETMR stems from our limited understanding of the spatiotemporal biological heterogeneity within patient tumor samples and a lack of preclinical models that adequately reflect the entire biological spectrum. Novel lipid-based therapeutics that encompass ganglioside-directed immunotherapy, targeting lipid metabolism and membrane lipid therapy, have shown efficacy in the treatment of brain tumors but have yet to be evaluated in the treatment of ETMR. We carried out mass spectrometry imaging on ETMR patient samples to identify the histology-specific accumulation of lipids within the diverse cell populations of the tumor microenvironment. Our preliminary studies identified the accumulation of glycosphingolipids, cardiolipins, phosphatidylinositols, and ceramide-1-phosphates within tumor cells, including the characteristic multilayered rosettes, and within different microvascular proliferations. All data were correlated to histopathology and Ki67 proliferation index. We next evaluated the lipid profiles in the patient-derived ETMR cell line, BT183, compared to control neural stem cells (NSCs), grown as 3D tumorspheres and neurospheres, respectively. From this data we identified lipids that accumulated in our patient samples and the ETMR cell line but were significantly reduced or not detected in the control NSCs. Analysis aimed at a systems biology approach to study the ETMR microenvironment using imaging mass cytometry for multiplex IHC and spatial transcriptomics to correlate lipidomic phenotype to distinct cell populations within the microenvironment are ongoing. Preclinical model development based on these findings and drug screening of therapeutics targeting these lipidomic pathways are also ongoing.
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