Magnetic Resonance Image-guided Focused Ultrasound (MRgFUS) has been used to achieve transient blood brain barrier (BBB) opening without tissue injury. Delivery of a targeted ultrasonic wave causes an interaction between administered microbubbles and the capillary bed resulting in enhanced vessel permeability. The use of MRgFUS in the brainstem has not previously been shown but could provide value in the treatment of tumours such as Diffuse Intrinsic Pontine Glioma (DIPG) where the intact BBB has contributed to the limited success of chemotherapy. Our primary objective was to determine whether the use of MRgFUS in this eloquent brain region could be performed without histological injury and functional deficits. Our secondary objective was to select an effective chemotherapeutic against patient derived DIPG cell lines and demonstrate enhanced brainstem delivery when combined with MRgFUS in vivo. Female Sprague Dawley rats were randomised to one of four groups: 1) Microbubble administration but no MRgFUS treatment; 2) MRgFUS only; 3) MRgFUS + microbubbles; and 4) MRgFUS + microbubbles + cisplatin. Physiological assessment was performed by monitoring of heart and respiratory rates. Motor function and co-ordination were evaluated by Rotarod and grip strength testing. Histological analysis for haemorrhage (H&E), neuronal nuclei (NeuN) and apoptosis (cleaved Caspase-3) was also performed. A drug screen of eight chemotherapy agents was conducted in three patient-derived DIPG cell lines (SU-DIPG IV, SU-DIPG XIII and SU-DIPG XVII). Doxorubicin was identified as an effective agent. NOD/SCID/GAMMA (NSG) mice were subsequently administered with 5 mg/kg of intravenous doxorubicin at the time of one of the following: 1) Microbubbles but no MRgFUS; 2) MRgFUS only; 3) MRgFUS + microbubbles and 4) no intervention. Brain specimens were extracted at 2 h and doxorubicin quantification was conducted using liquid chromatography mass spectrometry (LC/MS). BBB opening was confirmed by contrast enhancement on T1-weighted MR imaging and positive Evans blue staining of the brainstem. Normal cardiorespiratory parameters were preserved. Grip strength and Rotarod testing demonstrating no decline in performance across all groups. Histological analysis showed no evidence of haemorrhage, neuronal loss or increased apoptosis. Doxorubicin demonstrated cytotoxicity against all three cell lines and is known to have poor BBB permeability. Quantities measured in the brainstem of NSG mice were highest in the group receiving MRgFUS and microbubbles (431.5 ng/g). This was significantly higher than in mice who received no intervention (7.6 ng/g). Our data demonstrates both the preservation of histological and functional integrity of the brainstem following MRgFUS for BBB opening and the ability to significantly enhance drug delivery to the region, giving promise to the treatment of brainstem-specific conditions.

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Mucopolysaccharidosis type IIIA is a neurodegenerative lysosomal storage disorder characterized by progressive loss of learned skills, sleep disturbance and behavioural problems. Absent or greatly reduced activity of sulphamidase, a lysosomal protein, results in intracellular accumulation of heparan sulphate. Subsequent neuroinflammation and neurodegeneration typify this and many other lysosomal storage disorders. We propose that intra-cerebrospinal fluid protein delivery represents a potential therapeutic avenue for treatment of this and other neurodegenerative conditions; however, technical restraints restrict examination of its use prior to adulthood in mice. We have used a naturally-occurring Mucopolysaccharidosis type IIIA mouse model to determine the effectiveness of combining intravenous protein replacement (1 mg/kg) from birth to 6 weeks of age with intra-cerebrospinal fluid sulphamidase delivery (100 microg, fortnightly from 6 weeks) on behaviour, the level of heparan sulphate-oligosaccharide storage and other neuropathology. Mice receiving combination treatment exhibited similar clinical improvement and reduction in heparan sulphate storage to those only receiving intra-cerebrospinal fluid enzyme. Reductions in micro- and astrogliosis and delayed development of ubiquitin-positive lesions were seen in both groups. A third group of intravenous-only treated mice did not exhibit clinical or neuropathological improvements. Intra-cerebrospinal fluid injection of sulphamidase effectively, but dose-dependently, treats neurological pathology in Mucopolysaccharidosis type IIIA, even when treatment begins in mice with established disease.

Medulloblastoma is the most common malignant pediatric brain tumor, with metastases present at diagnosis conferring a poor prognosis. Mechanisms of dissemination are poorly understood and metastatic lesions are genetically divergent from the matched primary tumor. Effective and less toxic therapies that target both compartments have yet to be identified. Here, we report that the analysis of several large nonoverlapping cohorts of patients with medulloblastoma reveals MET kinase as a marker of sonic hedgehog (SHH)-driven medulloblastoma. Immunohistochemical analysis of phosphorylated, active MET kinase in an independent patient cohort confirmed its correlation with increased tumor relapse and poor survival, suggesting that patients with SHH medulloblastoma may benefit from MET-targeted therapy. In support of this hypothesis, we found that the approved MET inhibitor foretinib could suppress MET activation, decrease tumor cell proliferation, and induce apoptosis in SHH medulloblastomas in vitro and in vivo. Foretinib penetrated the blood-brain barrier and was effective in both the primary and metastatic tumor compartments. In established mouse xenograft or transgenic models of metastatic SHH medulloblastoma, foretinib administration reduced the growth of the primary tumor, decreased the incidence of metastases, and increased host survival. Taken together, our results provide a strong rationale to clinically evaluate foretinib as an effective therapy for patients with SHHdriven medulloblastoma. Cancer Res; 75(1); 134-46. Ó2014 AACR.