A BIOLOGICALLY INERT FLUID FOR USE IN THE TREATMENT OF A CNS DISORDER

Abstract

The present invention provides a biologically inert fluid for use in the treatment of a CNS disorder, wherein the biologically inert fluid is to be infused into the brain via convection enhanced delivery (CED) in combination with a therapeutic agent.

Claims

1. A biologically inert fluid for use in the treatment of a CNS disorder, wherein the biologically inert fluid is to be infused into the brain via convection enhanced delivery (CED) in combination with a therapeutic agent.

2. A biologically inert fluid for use according to claim 1, wherein the biologically inert fluid is to be infused prior to infusion of the therapeutic agent, simultaneously with the therapeutic agent and/or after infusion of the therapeutic agent.

3. A biologically inert fluid for use according to claim 1, wherein the biologically inert fluid is selected from one or more of phosphate buffered saline (PBS) or artificial cerebrospinal fluid (aCSF).

4. A biologically inert fluid for use according to claim 1, wherein the therapeutic agent is to be infused in the brain via an array of at least two catheters.

5. A biologically inert fluid for use according to claim 4, wherein the array comprises at least one central catheter for administration of the biologically inert fluid.

6. A biologically inert fluid for use according to claim 5, wherein the biologically inert fluid is to be infused through the central catheter prior to, subsequent to, or both prior to and subsequent to, infusion of the therapeutic agent.

7. A biologically inert fluid for use according to claim 1, wherein the therapeutic agent and biologically inert fluid are to be infused sequentially through the same catheter.

8. A biologically inert fluid for use according to claim 1, wherein the catheter is a reflux resistant catheter such as a stepped catheter or a recessed step catheter.

9. A biologically meet fluid for use according to claim 1, wherein the biologically inert fluid is to be infused at a flow rate of between 1 and 30 μL per minute, preferably-between 10 and 15 μL per minute.

10. A biologically inert fluid for use according to claim 1, wherein the biologically inert fluid and the therapeutic agent are to be infused into subcortical white matter of the brain to deliver the therapeutic agent to the cerebral cortex, the spinal cord, or both the cerebral cortex and spinal cord.

11. A biologically inert fluid for use according to claim 10, wherein the therapeutic agent is to be delivered to the frontal, parietal, temporal and/or occipital lobe of the cerebral cortex, or wherein the therapeutic agent is to be delivered to the whole cerebral cortex.

12. A biologically inert, fluid for use according to claim 10, wherein the therapeutic agent is to be delivered to the motor cortex, visual cortex, sensory cortex, associative cortex and/or auditory cortex.

13. A biologically inert fluid for use according to claim 1, wherein the CNS disorder is selected from neurodegenerative diseases, enzyme deficient conditions, neuroinflammatory diseases, acquired neurological injuries, neurological disorders or cancer.

14. A biologically inert fluid for use according to claim 13, wherein the neurodegenerative disease is selected from dementia, Lewy body disease, Alzheimer's disease, Huntington's disease, Amyotrophic Lateral Sclerosis (ALS), Multiple System Atrophy, Spinal muscular atrophy, Friedreich's Ataxia, Huntington's disease, Parkinson's disease, Parkinson's Plus syndromes, and Corticobasal degeneration.

15. A biologically inert fluid for use according to claim 14, wherein the enzyme deficient condition is selected from Lysosomal Storage diseases, Tay Sachs Disease, Sandhoff Disease, Neuronal Ceroid Lipofuscinosis, Hunter Syndrome, Hurler disease and Gaucher's Disease.

16. A biologically inert fluid for use according to claim 13, wherein the neuroinflammatory disease is selected from Multiple Sclerosis and prion diseases.

17. A biologically inert fluid for use according to claim 13, wherein the acquired neurological injury is stroke, traumatic brain injury or spinal cord injury.

18. A biologically inert fluid for use according to claim 1, wherein the therapeutic agent is selected from neurotrophins, gene therapies, enzymes, immune-therapy, SiRNAs, antisense oligonucleotides, chemotherapy, Auger electron emitters, immunotoxins, molecular targeted therapies, monoclonal antibodies, oncolytic viruses, viral vectors, chemotherapy agents, nanoparticles and botulinum toxin.

19. A method of treating a CNS disorder, the method comprising administering a biologically inert fluid and a therapeutic agent to a patient in need thereof, wherein the biologically inert fluid and therapeutic agent are infused into the brain via CED.

20. A method of treatment according to claim 19, wherein the biologically inert fluid is to be infused prior to infusion of the therapeutic agent, simultaneously with the therapeutic agent, after infusion of the therapeutic agent, or both prior to and after infusion of the therapeutic agent.

21. A method of treatment according to claim 19, wherein the biologically inert fluid is selected from one or more of phosphate buffered saline (PBS) or artificial cerebrospinal fluid (aCSF).

22. A method of treatment according to claim 19, wherein the therapeutic agent is to be infused in the brain via an array of at least two catheters.

23. A method of treatment according to claim 22, wherein the array comprises at least one central catheter for administration of the biologically inert fluid.

24. A method of treatment according to claim 23, wherein the biologically inert fluid is to be infused through the central catheter prior to, subsequent to, or both prior to and subsequent to, infusion of the therapeutic agent.

25. A method of treatment according to claim 19, wherein the therapeutic agent and biologically inert fluid are to be infused sequentially through the same catheter.

26. A method of treatment according to claim 19, wherein the catheter is a reflux resistant catheter such as a stepped catheter or recessed step catheter.

27. A method of treatment according to claim 19, wherein the biologically inert fluid is to be infused at a flow rate of between 1 and 30 μL per minute, preferably between 10 and 15 μL per minute.

28. A method of treatment according to claim 19, wherein the biologically inert fluid and the therapeutic agent are to be infused into subcortical white matter of the brain to deliver the therapeutic agent to the cerebral cortex and/or spinal cord.

29. A method of treatment according to claim 28, wherein the therapeutic agent is to be delivered to the frontal, parietal, temporal and/or occipital lobe of the cerebral cortex, or wherein the therapeutic agent is to be delivered to the whole cerebral cortex.

30. A method of treatment according to claim 28, wherein the therapeutic agent is to be delivered to motor cortex, visual cortex, sensory cortex, associative cortex and/or auditory cortex.

31. A method of treatment according to claim 19, wherein the CNS disorder is selected from neurodegenerative diseases, enzyme deficient conditions, neuroinflammatory diseases, acquired neurological injuries, neurological disorders or cancer.

32. A method of treatment according to claim 31, wherein the neurodegenerative disease is selected from dementia, Lewy body disease, Alzheimer's disease, Huntington's disease, Amyotrophic Lateral Sclerosis (ALS), Multiple System Atrophy, Spinal muscular atrophy, Friedreich's Ataxia, Huntington's disease, Parkinson's disease, Parkinson's plus syndromes, and Corticobasal degeneration.

33. A method of treatment according to claim 31, wherein the enzyme deficient condition is selected from Lysosomal Storage diseases, Tay Sachs Disease, Sandhoff Disease, Neuronal. Ceroid Lipofuscinosis, Hunter Syndrome, Hurler disease and Gaucher's Disease.

34. A method of treatment according to claim 31, wherein the neuroinflammatory disease is selected from Multiple Sclerosis and priori diseases.

35. A method of treatment according to claim 31, wherein the acquired neurological injury is stroke, traumatic brain injury or spinal cord injury.

36. A method of treatment according to claim 31, wherein the neurological disorder is epilepsy.

37. A method of treatment according to claim 19, wherein the therapeutic agent is selected from neurotrophins, gene therapies, enzymes, immune-therapy, SiRNAs, antisense oligonucleotides, chemotherapy, Auger electron emitters, immunotoxins, molecular targeted therapies, monoclonal antibodies, oncolytic viruses, viral vectors, chemotherapy agents, nanoparticles and botulinum toxin.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0042] The invention will now be described in detail, by way of example only, with reference to the figures.

[0043] FIG. 1 shows a 3-dimensional perspective view of the brain with catheter entry points in the frontal poles.

[0044] FIG. 2 shows a semi-transparent brain with three subcortical frontal catheters and a single orbito-frontal catheter for delivery of a therapeutic agent plus a deep white matter catheter (5) for delivery of a biologically inert fluid. The planned infusion volumes for the catheter are shown as ovoid volumes (10).

[0045] FIG. 3A shows a trajectory view of the frontal, deep white matter catheter (5) that is reconstructed in a sagittal plane through the head. The planned infusion volume of biologically inert fluid to be delivered by this catheter is shown in outline (10).

[0046] FIG. 3B shows a coronal section through the anterior frontal lobes with cross-sectional views of three subcortical catheters (6) and one orbito-frontal catheter (7) for delivering a therapeutic agent plus a cross-sectional view of a deep white matter catheter (5) for delivering a biologically inert fluid.

[0047] FIG. 3C shows a coronal section through the posterior frontal lobes with cross-sectional views of three subcortical catheters (6) for delivering a therapeutic agent plus a cross-sectional view of a deep white matter catheter (5) for delivering a biologically inert fluid. Labels indicate the lateral ventricle (1), the caudate nucleus (2), the putamen (3) and the globus pallidus (4).

[0048] FIG. 4 shows a coronal section through the posterior frontal lobe (as per the MRI image FIG. 3C). Three subcortical catheters 6 and one deep white matter catheter 5 are implanted in an antero-posterior trajectory. The three subcortical catheters are delivering a therapeutic agent and the deep white matter catheter is delivering a biologically inert fluid.

[0049] FIG. 5 shows the latter stages of the infusion with the deep white matter catheter 5 driving (as indicated by arrows) the therapy towards the cortical grey matter. Labelled are the lateral ventricle (1), the caudate nucleus (2), the putamen (3), the globus pallidus 4), the corpus callosum (8), and the internal capsule (white matter) (9).

[0050] FIG. 6 shows an embodiment of the invention with the infusion of a biologically inert fluid following the infusion of the therapeutic agent in the subcortical catheters 6. In this instance this works in cooperation with the deep white matter infusion of biologically inert fluid 5 to further drive (as indicated by arrows) the therapeutic agent into the cortical grey matter.

[0051] FIG. 7 shows (A) the sheep model used; (B) a schematic illustration of the position of the motor cortex in the brain (blue); (C) the position of catheters used for a test infusion of 500 μL of gadolinium to the sheep motor cortex (yellow catheter=aCSF; white catheter=contrast, i.e. gadolinium); (D) a post-infusion sagittal view of gadolinium distribution; (E) a post-infusion axial view of gadolinium distribution; and (F) a post-infusion coronal view of gadolinium distribution.

[0052] FIG. 8 shows a mid-sagittal T2 image of sheep brain with 3D reconstruction of the volume of distribution of 500 μL of infused gadolinium in the motor cortex (blue). The sub-cortical catheter that delivers the gadolinium is shown in yellow. Also shown are the deep white matter catheter (white) and the trans-cutaneous port located in the occipital bone. The volume of distribution/volume of infusion ratio (Vd/Vi)=4:1.

[0053] FIG. 9 shows a sagittal section of sheep brain post-infusion of AAV9-CMV-Mcherry to the motor cortex. MCherry fluorescence indicates transfection of primary motor neurons (pyramidal cells).

[0054] FIG. 10 shows anterograde transport of MCherry in the corticospinal and reticulospinal tracts and in the anterior horn cells of the sheep.

EXAMPLES

Example 1

[0055] Delivery of Therapeutic Agents to the Frontal Lobe Cortex for the Treatment of Alzheimer's Disease, Amyotrophic Lateral Sclerosis, Friedreich's Ataxia, Huntington's Disease, Enzyme Deficiency Syndromes, Lysosomal Storage Diseases, Stroke Repair, Brain Injury, Focal Epilepsy and Other Neurological And Psychiatric Diseases (Intrinsic Depression and Schizophrenia)

[0056] There are a number of challenges in delivering therapeutic agents to the frontal lobe cortex due to its convoluted morphology and volume. Each frontal lobe cortex volume is approximately 135 cm.sup.3 and constitutes 20% of the total cerebral cortex volume (Kennedy et al). To distribute a therapeutic agent to the deepest half of the cortex (which contains layer 5), assuming a Vd/Vi of 5:1, will require a Vi of 13.5 ml. Delivery of therapeutic agents exclusively to the cortex by CED is not feasible due to its convoluted morphology, but this can be achieved with subcortical white matter infusions. Infusions into the white matter will preferentially flow down white matter tracts as this is the path of least resistance.

[0057] In a worst case scenario the frontal white matter will need to be filled in its entirety before a sufficient pressure gradient is established to drive the infusate into the grey matter. The total cerebral white matter volume is 390 cm.sup.3 (Lüders et al), thus estimating the white matter volume of one frontal lobe to be 20% of the total cerebral white matter, its volume is 78 cm.sup.3. The Vd/Vi for white matter is 2:1 so that 39 ml of infusate will have to be delivered in this example before a sufficient pressure gradient is established to drive the therapy into the cortical grey matter. Thus the total volume of infusate required to cover a frontal lobe will be 39 ml+13.5 ml=52.5 ml. If a catheter can deliver 7-10 m per day (10-15 μL per minute for 12 hours) 5-7 catheters will be needed to fill this volume. Nevertheless in this instance only ⅓rd of the infused drug will be in the therapeutic target and the remaining ⅔rds will be ineffective and may cause unnecessary toxicity.

Treatment Method Proposed in the Present Invention:

[0058] An example of the method for delivering a therapeutic agent to the frontal lobe cortex is shown in FIGS. 1-6. Here three catheters for delivery of the therapeutic agent are implanted in a fan-shaped antero-posterior trajectory under the frontal cortex with their entry points at the frontal pole and each catheter tip is positioned beneath the motor cortex. A further catheter is implanted to deliver therapy in the sub-cortical white matter of the orbito-frontal cortex with a fronto-polar entry point. One catheter (yellow) for delivery of an inert fluid, preferably artificial CSF, is placed deep in the frontal white matter in an antero-posterior direction with an entry point at the frontal pole and distal end deep to the motor cortex.

[0059] Preferably the catheters are reflux resistant, stepped or recess-stepped catheters with adjustable step lengths to modulate the shape of the infused volume of distribution (suitable catheters are described WO03/077785). The catheters are surgically implanted with image guidance using stereotactic methods that are well established. For some indications, such as for viral vector delivery, the catheters may be implanted for one-off infusions and then removed. For treatments that require repeated infusions the catheters may be chronically implanted and infused periodically via a trans-cutaneous port as described WO2008/062173 and/or WO2011/098769. Alternatively subcutaneous pumps may be connected to individual catheters for chronic-intermittent infusions.

[0060] It is of note that the method described above of delivering therapeutic agents to the frontal cortical grey matter may be applied to the delivery of therapies to the cortical grey matter of the occipital, parietal, and temporal lobes or indeed of combinations thereof or to the whole brain including the cerebellum.

Example 2

[0061] Delivery of Viral Vectors that Undergo Anterograde Axonal Transport, Including AAV2, 5, 8, and 9 to the Motor Cortex for the Treatment of Amyotrophic Lateral Sclerosis (GDNF and/or VEGF Transgene), Spinal Cord Injury (GNDF and/or VEGF Transgene), Friedreich's Ataxia (Frataxin Transgene, and/or GNDF and/or VEGF Transgene), Spinal Muscular Atrophy (SMN1 Transgene, and/or GNDF and/or VEGF Transgene) and Multiple Sclerosis (GDNF).

[0062] Here three or more catheters for delivery of the therapeutic agent are implanted in a fan-shaped antero-posterior trajectory under the frontal cortex with their entry points at the frontal pole and each catheter tip is positioned beneath the motor cortex. Each catheter step length is adjusted so that the infusate is delivered beneath the motor and premotor cortex. Typically the catheter step length would be 5-20 mm. One or more catheters for delivery of an inert fluid, preferably artificial CSF, are placed deep to the subcortical catheters. These are positioned in the white matter in an antero-posterior direction with an entry point at the frontal pole and distal end deep to the motor cortex.

[0063] The subcortical catheters deliver the viral vector carrying the appropriate transgene in an inert diluent, such as aCSF, at a concentration that will be sufficient to transfect motor neurons in layer 5 of the cortex. Typically this is in the range of 1×10.sup.12 VG/ml to 5×10.sup.13 VG/ml. The rate of infusion is preferably between 5 and 15 μL per minute. A radio-opaque contrast agent such as Gadolinium-DTPA may also be co-infused with the vector. Inert fluid, preferably aCSF will be infused through the more deeply placed catheters at the same time as the therapeutic agent is infused, however, infusion of the latter may commence before commencing infusions of the therapy so that a pressure gradient is established that drives the flow of the vector when it is infused towards the cortex. Similarly when the therapy has been delivered, the continued infusion of aCSF would be desirable so that more of the vector is driven towards the cortex. The flow rate of the catheters infusing aCSF may be higher than the catheters infusing the therapy i.e. 10-15 μL/min verses 5-10 μL/min to increase the pressure gradient.

[0064] Example 3

[0065] Blocking the flow of infused therapies from entering critical brain volumes, e.g. the medulla when infusing the pons in DIPG. In this instance aCSF is infused into the critical structure to protect it from an influx of potentially toxic drug.

Example 4

[0066] Subcortical infusion to the sensory cortex with retrogradely transporting vectors including AAVS may be used to deliver neurotrophins such as GDNF down the spinal cord to peripheral sensory neurons to treat peripheral sensory neuropathy.

Example 5

Bio-Distribution of AAV9-MCherry Delivered to the Motor Cortex of a Large Animal Model (Adult Romney Marsh Sheep)

Method:

[0067] A Romney Marsh adult sheep (FIG. 7) was anaesthetised and its head fixed in a custom made head fixation device. T1 and T2 volumetric MRI images were acquired of the sheep's head with a radio-opaque fiducial fixed to the head frame.

[0068] The trajectories of 4 implantable CED micro-catheters were planned from the MRI volumes using surgical planning software. The sheep's motor cortex occupies the medial aspect of the frontal lobe and 2 posterior to anterior catheter trajectories were planned for each hemisphere. These included a subcortical and a deep white matter catheter in a parallel orientation in each hemisphere with entry points in the parietal region (FIG. 7).

[0069] With reference to the fiducials visible on the MRI image volumes the surgical plan was co-registered with a CRW stereotactic frame (Radionics Inc. Mass.) that was attached to the sheep head fixation device. This then facilitated implantation of the catheters under stereotactic guidance. The catheters were connected to independent channels in a trans-cutaneous port.

[0070] Prior to delivering AAV to the sheep motor cortex a test infusion of an equivalent volume of gadolinium (500 μL to each motor cortex) was first conducted to establish its volume of distribution. The infusions were carried with the sheep under general anaesthesia in an MRI scanner. Due to the convoluted morphology of the motor cortex, delivery of the gadolinium (and subsequently the vector) was achieved by infusing it into the subcortical white matter whilst simultaneously infusing artificial cerebrospinal fluid (aCSF) into the deep white matter, both at a flow-rate of 5 μL per minute. The pressure gradient created by infusing aCSF into the white matter drives the gadolinium or vector into the cortex. When the latter had been infused a further 500 μL of aCSF was delivered down each of the sub-cortical and deep white matter catheters at 5 μL per minute to further drive the gadolinium into the cortical grey matter (FIG. 8).

[0071] Having confirmed satisfactory motor cortical coverage with the test infusion of gadolinium the sheep was recovered and 1 week later underwent infusions of AAV9-CMV-MCherry (500 μL of 2.2×10.sup.13 VG/ml) into the left motor cortex using the above described method.

[0072] The sheep was housed in a pen with other sheep for 6 weeks prior to being euthanized and perfusion fixated. The brain was cryopreserved and retained for histological analysis.

[0073] Histological Methods: The fixed brain was sectioned at 100 μm increments in the sagittal plane and from the level of the cerebral peduncles the pons and medulla were sectioned axially at 40 μm increments.

[0074] MCherry fluorescence was visualised using florescence microscopy.

[0075] Every 25th section was processed for immunohistochemistry and H&E staining.

Results: 1. Bio-distribution of MCherry florescent protein transgene in the brain and spinal cord following infusion of AAV9-MCherry into the left motor cortex.

Brain:

[0076] MCherry fluorescence was observed throughout layer 5 of the motor cortex with pyramidal cells and the cortico-spinal tracts being strongly fluorescent (FIG. 9). Less intense fluorescence was observed throughout all layers of the cortex, being expressed in both neurons and glia.

Spinal Cord:

[0077] Axial sections through the cervical spinal cord show anterograde transport of MCherry in the anterior and lateral corticospinal tracts as well as the ventral white commissure. MCherry is also seen in the medial and lateral reticulospinal tracts and anterior horn cells indicating trans-synaptic transfection of AAV9 (FIG. 10).

Conclusion:

[0078] The present study demonstrates that it is possible to transfect the motor cortex and spinal cord by infusing a gene therapy vector and cargo into sub-motor cortical white matter of the brain and utilising a pressure gradient created by infusion of aCSF into white matter to drive the gene therapy vector and cargo into the cortex.

References

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