Therapeutic strategies for diffuse midline glioma from high-throughput combination drug screening.

Diffuse midline gliomas (DMGs) are universally lethal malignancies occurring chiefly during childhood and involving midline structures of the central nervous system, including thalamus, pons, and spinal cord. These molecularly related cancers are characterized by high prevalence of the histone H3K27M mutation. In search of effective therapeutic options, we examined multiple DMG cultures in sequential quantitative high-throughput screens (HTS) of 2706 approved and investigational drugs. This effort generated 19,936 single-agent dose responses that inspired a series of HTS-enabled drug combination assessments encompassing 9195 drug-drug examinations. Top combinations were validated across patient-derived cell cultures representing the major DMG genotypes. In vivo testing in patient-derived xenograft models validated the combination of the multi-histone deacetylase (HDAC) inhibitor panobinostat and the proteasome inhibitor marizomib as a promising therapeutic approach. Transcriptional and metabolomic surveys revealed substantial alterations to key metabolic processes and the cellular unfolded protein response after treatment with panobinostat and marizomib. Mitigation of drug-induced cytotoxicity and basal mitochondrial respiration with exogenous application of nicotinamide mononucleotide (NMN) or exacerbation of these phenotypes when blocking nicotinamide adenine dinucleotide (NAD+) production via nicotinamide phosphoribosyltransferase (NAMPT) inhibition demonstrated that metabolic catastrophe drives the combination-induced cytotoxicity. This study provides a comprehensive single-agent and combinatorial drug screen for DMG and identifies concomitant HDAC and proteasome inhibition as a promising therapeutic strategy that underscores underrecognized metabolic vulnerabilities in DMG.

ALK2 inhibitors display beneficial effects in preclinical models of ACVR1 mutant diffuse intrinsic pontine glioma.

Diffuse intrinsic pontine glioma (DIPG) is a lethal childhood brainstem tumour, with a quarter of patients harbouring somatic mutations in ACVR1, encoding the serine/threonine kinase ALK2. Despite being an amenable drug target, little has been done to-date to systematically evaluate the role of ACVR1 in DIPG, nor to screen currently available inhibitors in patient-derived tumour models. Here we show the dependence of DIPG cells on the mutant receptor, and the preclinical efficacy of two distinct chemotypes of ALK2 inhibitor in vitro and in vivo. We demonstrate the pyrazolo[1,5-a]pyrimidine LDN-193189 and the pyridine LDN-214117 to be orally bioavailable and well-tolerated, with good brain penetration. Treatment of immunodeprived mice bearing orthotopic xenografts of H3.3K27M, ACVR1R206H mutant HSJD-DIPG-007 cells with 25 mg/kg LDN-193189 or LDN-214117 for 28 days extended survival compared with vehicle controls. Development of ALK2 inhibitors with improved potency, selectivity and advantageous pharmacokinetic properties may play an important role in therapy for DIPG patients.

Repurposing the anti-epileptic drug sodium valproate as an adjuvant treatment for diffuse intrinsic pontine glioma.

Targeting epigenetic changes in diffuse intrinsic pontine glioma (DIPG) may provide a novel treatment option for patients. This report demonstrates that sodium valproate, a histone deacetylase inhibitor (HDACi), can increase the cytotoxicity of carboplatin in an additive and synergistic manner in DIPG cells in vitro. Sodium valproate causes a dose-dependent decrease in DIPG cell viability in three independent ex vivo cell lines. Furthermore, sodium valproate caused an increase in acetylation of histone H3. Changes in cell viability were consistent with an induction of apoptosis in DIPG cells in vitro, determined by flow cytometric analysis of Annexin V staining and assessment of apoptotic markers by western blotting. Subsequently, immunofluorescent staining of neuronal and glial markers was used to determine toxicity in normal rat hippocampal cells. Pre-treatment of cells with sodium valproate enhanced the cytotoxic effects of carboplatin, in three DIPG cell lines tested. These results demonstrate that sodium valproate causes increased histone H3 acetylation indicative of HDAC inhibition, which is inversely correlated with a reduction in cell viability. Cell viability is reduced through an induction of apoptosis in DIPG cells. Sodium valproate potentiates carboplatin cytotoxicity and prompts further work to define the mechanism responsible for the synergy between these two drugs and determine in vivo efficacy. These findings support the use of sodium valproate as an adjuvant treatment for DIPG.

Preclinical evaluation of convection-enhanced delivery of liposomal doxorubicin to treat pediatric diffuse intrinsic pontine glioma and thalamic high-grade glioma.

OBJECTIVE Pediatric high-grade gliomas (pHGGs) including diffuse intrinsic pontine gliomas (DIPGs) are primary brain tumors with high mortality and morbidity. Because of their poor brain penetrance, systemic chemotherapy regimens have failed to deliver satisfactory results; however, convection-enhanced delivery (CED) may be an alternative mode of drug delivery. Anthracyclines are potent chemotherapeutics that have been successfully delivered via CED in preclinical supratentorial glioma models. This study aims to assess the potency of anthracyclines against DIPG and pHGG cell lines in vitro and to evaluate the efficacy of CED with anthracyclines in orthotopic pontine and thalamic tumor models. METHODS The sensitivity of primary pHGG cell lines to a range of anthracyclines was tested in vitro. Preclinical CED of free doxorubicin and pegylated liposomal doxorubicin (PLD) to the brainstem and thalamus of naïve nude mice was performed. The maximum tolerated dose (MTD) was determined based on the observation of clinical symptoms, and brains were analyzed after H & E staining. Efficacy of the MTD was tested in adult glioma E98-FM-DIPG and E98-FM-thalamus models and in the HSJD-DIPG-007-Fluc primary DIPG model. RESULTS Both pHGG and DIPG cells were sensitive to anthracyclines in vitro. Doxorubicin was selected for further preclinical evaluation. Convection-enhanced delivery of the MTD of free doxorubicin and PLD in the pons was 0.02 mg/ml, and the dose tolerated in the thalamus was 10 times higher (0.2 mg/ml). Free doxorubicin or PLD via CED was ineffective against E98-FM-DIPG or HSJD-DIPG-007-Fluc in the brainstem; however, when applied in the thalamus, 0.2 mg/ml of PLD slowed down tumor growth and increased survival in a subset of animals with small tumors. CONCLUSIONS Local delivery of doxorubicin to the brainstem causes severe toxicity, even at doxorubicin concentrations that are safe in the thalamus. As a consequence, the authors could not establish a therapeutic window for treating orthotopic brainstem tumors in mice. For tumors in the thalamus, therapeutic concentrations to slow down tumor growth could be reached. These data suggest that anatomical location determines the severity of toxicity after local delivery of therapeutic agents and that caution should be used when translating data from supratentorial CED studies to treat infratentorial tumors.

Management of diffuse pontine gliomas in children: recent developments.

The prognosis for children with diffuse intrinsic pontine gliomas (DIPGs) is dismal. Although DIPGs constitute only 10-15 % of all pediatric brain tumors, they are the main cause of death in this group with a median survival of less than 12 months. Standard therapy involves radiotherapy, which produces transient neurologic improvement. Despite several clinical trials having been conducted, including trials on targeted agents to assess their efficacy, there is no clear improvement in prognosis. However, knowledge of DIPG biology is increasing, mainly as a result of research using biopsy and autopsy samples. In this review, we discuss recent studies in which systemic therapy was administered prior to, concomitantly with, or after radiotherapy. The discussion also includes novel therapeutic options in DIPG. Continuing multimodal and multitargeted therapies might lead to an improvement in the dismal prognosis of the disease.

Pharmacokinetic investigation of increased efficacy against malignant gliomas of carboplatin combined with hyperbaric oxygenation.

The efficacy of intravenous administration of 400 mg carboplatin/m(2) body surface area over 60 minutes combined with hyperbaric oxygenation (HBO) therapy (0.2 MPa for 60 min) was investigated in 6 Japanese patients (aged 36-67 years) with malignant or brainstem gliomas. Plasma ultra-filtrate samples were analyzed by high-performance liquid chromatography to evaluate the relationship between efficacy and pharmacokinetics. Brain tumor response was evaluated by magnetic resonance imaging as a function of maximum plasma concentration, area under the curve, or mean residence time (MRT) for carboplatin. The MRT for carboplatin in the complete or partial response group (mean +/- standard deviation 4.3 +/- 1.7 hrs; 6 courses in 3 patients) was significantly longer (p < 0.05) than that in the progressive disease group (2.4 +/- 0.1 hrs; 3 courses in 3 patients), but maximum plasma concentration and area under the curve showed no differences. These results suggest that HBO therapy prolongs the biological residence time of carboplatin. MRT for carboplatin may be useful for predicting continuation or modification of chemotherapy and/or clinical antitumor effects in patients with malignant gliomas.

Targeted therapy with antineoplastons A10 and AS2-1 of high-grade, recurrent, and progressive brainstem glioma.

BACKGROUND: Brainstem glioma carries the worst prognosis of all malignancies of the brain. Most patients with brainstem glioma fail standard radiation therapy and chemotherapy and do not survive longer than 2 years. Treatment is even more challenging when an inoperable tumor is of high-grade pathology (HBSG). The objective of this report is to summarize the outcome of patients with HBSG treated with antineoplastons in 4 phase 2 trials. PATIENTS: The following group of 18 patients was evaluable: 4 patients with glioblastomas and 14 patients with anaplastic HBSG. Fourteen patients had diffuse intrinsic tumors. Twelve patients suffered from recurrence, and 6 patients did not have radiation therapy or chemotherapy. METHODS: Antineoplastons, which consist of antineoplaston A10 (A10I) and AS2-1 injections, were given in escalating doses by intravenous injections. The median duration of antineoplaston administration was 5 months, and the average dosage of A10I was 9.22 g/kg/d and of AS2-1 was 0.31 g/kg/d. Responses were assessed by gadolinium-enhanced magnetic resonance imaging and positron emission tomography. RESULTS: The overall survival at 2 and 5 years was 39% and 22%, respectively, and maximum survival was more than 17 years for a patient with anaplastic astrocytoma and more than 5 years for a patient with glioblastoma. Progression-free survival at 6 months was 39%. Complete response was achieved in 11%, partial response in 11%, stable disease in 39%, and progressive disease in 39% of patients. Antineoplastons were tolerated very well with 1 case of grade 4 toxicity (reversible anemia). CONCLUSION: Antineoplastons contributed to more than a 5-year survival in recurrent diffuse intrinsic glioblastomas and anaplastic astrocytomas of the brainstem in a small group of patients.

Long-term survival and complete response of a patient with recurrent diffuse intrinsic brain stem glioblastoma multiforme.

Recurrent diffuse intrinsic brain stem glioblastoma multiforme carries an extremely poor prognosis and a median survival of less than 7 months. In this article, the authors report good results in a 40-year-old man diagnosed with glioblastoma multiforme who received antineoplastons. The patient's brain tumor was diagnosed in May 1999, and he subsequently underwent subtotal tumor resection and standard radiation therapy. Magnetic resonance imaging and positron emission tomography scans documented his tumor recurrence. Approximately 2 months after completion of radiation therapy, he was admitted for administration of intravenous antineoplastons A10 and AS2-1 through a subclavian venous catheter by intermittent bolus injections 6 times per day using a portable pump. Administration of antineoplastons A10 and AS2-1 was over 655 consecutive days with the exception of a few short interruptions. The maximum dosage of A10 was 8.15 g/kg/d and AS2-1 0.35 g/kg/d. Antineoplastons A10 and AS2-1 administration was very well tolerated with only mild reversible side effects. Follow-up magnetic resonance imaging and positron emission tomography scans revealed decrease and eventually disappearance of the tumor. A complete response was documented after approximately 1 year of antineoplastons A10 and AS2-1 administration. More than 4 years later, off antineoplastons A10 and AS2-1, the patient is tumor free, able to carry on normal activities, and works full-time, and his Karnofsky Performance Status increased from 50 to 100. Extensive phase II trials with antineoplastons A10 and AS2-1 in patients with glioblastoma multiforme are nearing completion. These trials may provide more data regarding the efficacy of antineoplastons A10 and AS2-1 in the treatment of glioblastoma multiforme in untreated patients compared to the results in those patients with tumor recurrence after radiation therapy.

A new homeopathic approach to neoplastic diseases: from cell destruction to carcinogen-induced apoptosis.

Neoplastic diseases are now among the most commonly seen conditions. Orthodox, non-surgical approaches, including chemotherapy and radiotherapy, have variable results, but many adverse affects that limit their use. These are sometimes the direct cause of death. More patients are choosing alternative treatments, mainly the homeopathic and herbal-nutrition approach. Homeopathy does not have highly effective remedies for cancer in its literature, and has been limited to palliating the adverse effects of chemo/radiotherapy. Research into substances that can produce neoplastic diseases (carcinogens), may lead to them being used to treat the cancer they cause, according to the principle of similarity. I have used ultra-low doses (1 x 10(-10) to 10(-12) molar) of chemical carcinogens for 3-24 months, which have been given to cancer patients, usually in conjunction with conventional treatment. Using this procedure, complete remission or life extension has been achieved for some cancer cases. Three clinical cases are presented: a man with undifferentiated lung cancer; a child with an astrocytoma and a woman with leiomyosarcoma.