Temporary blood-brain barrier disruption by low intensity pulsed ultrasound increases carboplatin delivery and efficacy in preclinical models of glioblastoma.

INTRODUCTION: Glioblastoma (GBM) is the most common and aggressive primary brain cancer in adults. Few cytotoxic chemotherapies have been shown to be effective against GBM, due in part to the presence of the blood-brain barrier (BBB), which reduces the penetration of chemotherapies from the blood to the brain. Ultrasound-induced BBB opening (US-BBB) has been shown to increase the penetration of multiple chemotherapeutic agents in the brain in animal models. In the current study, the anti-tumor activity of carboplatin chemotherapy with and without US-BBB was investigated in several GBM mouse models. METHODS: First, the IC50 of two commercial (U87 and U251) and six patient-derived GBM cell lines (PDCL) to carboplatin was measured. Next, U87 was subcutaneously grafted to a nude mouse model to test the in vivo response of the tumor to carboplatin in the absence of the BBB. Lastly, nude mice bearing orthotopically xenografted GBM cell lines (U87 or a PDCL) were randomized to four experimental groups: (i) untreated, (ii) US-BBB alone, (iii) carboplatin alone and, (iv) carboplatin + US-BBB. Mice were treated once weekly for 4 weeks and monitored for toxicity, tumor growth, and survival. RESULTS: Carboplatin plus US-BBB enhanced survival (p = 0.03) and delayed tumor growth (p < 0.05) of GBM-bearing mice compared to carboplatin alone, with a 4.2-fold increase of carboplatin penetration in the brain, without evidence of significant neurological or systemic toxicity. CONCLUSIONS: Carboplatin efficacy was enhanced in GBM mouse models with US-BBB and appears to be a promising chemotherapy for this approach.

Correction to: ATP binding cassette (ABC) transporters: expression and clinical value in glioblastoma.

The names of authors Marc Sanson and Jean-Yves Delattre were incorrectly presented in the initial online publication. The original article has been corrected.

ATP binding cassette (ABC) transporters: expression and clinical value in glioblastoma.

ATP-binding cassette transporters (ABC transporters) regulate traffic of multiple compounds, including chemotherapeutic agents, through biological membranes. They are expressed by multiple cell types and have been implicated in the drug resistance of some cancer cells. Despite significant research in ABC transporters in the context of many diseases, little is known about their expression and clinical value in glioblastoma (GBM). We analyzed expression of 49 ABC transporters in both commercial and patient-derived GBM cell lines as well as from 51 human GBM tumor biopsies. Using The Cancer Genome Atlas (TCGA) cohort as a training dataset and our cohort as a validation dataset, we also investigated the prognostic value of these ABC transporters in newly diagnosed GBM patients, treated with the standard of care. In contrast to commercial GBM cell lines, GBM-patient derived cell lines (PDCL), grown as neurospheres in a serum-free medium, express ABC transporters similarly to parental tumors. Serum appeared to slightly increase resistance to temozolomide correlating with a tendency for an increased expression of ABCB1. Some differences were observed mainly due to expression of ABC transporters by microenvironmental cells. Together, our data suggest that the efficacy of chemotherapeutic agents may be misestimated in vitro if they are the targets of efflux pumps whose expression can be modulated by serum. Interestingly, several ABC transporters have prognostic value in the TCGA dataset. In our cohort of 51 GBM patients treated with radiation therapy with concurrent and adjuvant temozolomide, ABCA13 overexpression is associated with a decreased progression free survival in univariate (p < 0.01) and multivariate analyses including MGMT promoter methylation (p = 0.05) suggesting reduced sensitivity to temozolomide in ABCA13 overexpressing GBM. Expression of ABC transporters is: (i) detected in GBM and microenvironmental cells and (ii) better reproduced in GBM-PDCL. ABCA13 expression is an independent prognostic factor in newly diagnosed GBM patients. Further prospective studies are warranted to investigate whether ABCA13 expression can be used to further personalize treatments for GBM.

Evaluating Efficacy of Peptide-Delivered Oligonucleotides Using the Severe Taiwanese SMA Mouse Model.

Oligonucleotides (ONs) are therapeutic macromolecules with great potential for the treatment of neurological conditions, including spinal muscular atrophy (SMA), a neurodegenerative disease. However, the neurovascular unit severely limits their distribution to the neural parenchyma of the brain and the spinal cord. Cell-penetrating peptides (CPPs) can be conjugated to oligonucleotides to increase their delivery across biological barriers. In this chapter, we describe the synthesis and conjugation of CPPs to oligonucleotides, and the use of a severe SMA mouse model to test in vivo the efficacy of CPP-delivered oligonucleotides, using ELISA, western blot, and TaqMan™ RT-qPCR assays.

Antibody-oligonucleotide conjugate achieves CNS delivery in animal models for spinal muscular atrophy.

Antisense oligonucleotides (ASOs) have emerged as one of the most innovative new genetic drug modalities. However, their high molecular weight limits their bioavailability for otherwise-treatable neurological disorders. We investigated conjugation of ASOs to an antibody against the murine transferrin receptor, 8D3130, and evaluated it via systemic administration in mouse models of the neurodegenerative disease spinal muscular atrophy (SMA). SMA, like several other neurological and neuromuscular diseases, is treatable with single-stranded ASOs that modulate splicing of the survival motor neuron 2 (SMN2) gene. Administration of 8D3130-ASO conjugate resulted in elevated levels of bioavailability to the brain. Additionally, 8D3130-ASO yielded therapeutic levels of SMN2 splicing in the central nervous system of adult human SMN2-transgenic (hSMN2-transgenic) mice, which resulted in extended survival of a severely affected SMA mouse model. Systemic delivery of nucleic acid therapies with brain-targeting antibodies offers powerful translational potential for future treatments of neuromuscular and neurodegenerative diseases.

Mesyl Phosphoramidate Oligonucleotides as Potential Splice-Switching Agents: Impact of Backbone Structure on Activity and Intracellular Localization.

A series of 2'-deoxy and novel 2'-O-methyl and 2'-O-(2-methoxyethyl) (2'-MOE) oligonucleotides with internucleotide methanesulfonyl (mesyl, µ) or 1-butanesulfonyl (busyl, ß) phosphoramidate groups has been synthesized for evaluation as potential splice-switching oligonucleotides. Evaluation of their splice-switching activity in spinal muscular atrophy patient-derived fibroblasts revealed no significant difference in splice-switching efficacy between 2'-MOE mesyl oligonucleotide and the corresponding phosphorothioate (nusinersen). Yet, a survival study with model neonatal mice has shown the antisense 2'-MOE mesyl oligonucleotide to be inferior to nusinersen at the highest dose of 40 mg/kg. A reason for their lower activity in vivo as ascertained by cellular uptake study by fluorescent confocal microscopy in HEK293 cell line could possibly be ascribed to compromised endosomal release and/or nuclear uptake of the 2'-OMe or 2'-MOE µ- and ß-oligonucleotides compared to their phosphorothioate analog.