Classifications

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  • A61N1/372—Arrangements in connection with the implantation of stimulators
  • A61N1/37211—Means for communicating with stimulators
  • A61N1/37217—Means for communicating with stimulators characterised by the communication link, e.g. acoustic or tactile
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  • A61M37/00—Other apparatus for introducing media into the body; Percutany, i.e. introducing medicines into the body by diffusion through the skin
  • A61M37/0092—Other apparatus for introducing media into the body; Percutany, i.e. introducing medicines into the body by diffusion through the skin using ultrasonic, sonic or infrasonic vibrations, e.g. phonophoresis
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  • A61K9/0002—Galenical forms characterised by the drug release technique; Application systems commanded by energy
  • A61K9/0009—Galenical forms characterised by the drug release technique; Application systems commanded by energy involving or responsive to electricity, magnetism or acoustic waves; Galenical aspects of sonophoresis, iontophoresis, electroporation or electroosmosis
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  • A61N1/36—Applying electric currents by contact electrodes alternating or intermittent currents for stimulation
  • A61N1/36014—External stimulators, e.g. with patch electrodes
  • A61N1/36017—External stimulators, e.g. with patch electrodes with leads or electrodes penetrating the skin
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  • A61N1/32—Applying electric currents by contact electrodes alternating or intermittent currents
  • A61N1/36—Applying electric currents by contact electrodes alternating or intermittent currents for stimulation
  • A61N1/36014—External stimulators, e.g. with patch electrodes
  • A61N1/36025—External stimulators, e.g. with patch electrodes for treating a mental or cerebral condition
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  • A61N1/40—Applying electric fields by inductive or capacitive coupling ; Applying radio-frequency signals
• • C—CHEMISTRY; METALLURGY
  • C12—BIOCHEMISTRY; BEER; SPIRITS; WINE; VINEGAR; MICROBIOLOGY; ENZYMOLOGY; MUTATION OR GENETIC ENGINEERING
  • C12N—MICROORGANISMS OR ENZYMES; COMPOSITIONS THEREOF; PROPAGATING, PRESERVING, OR MAINTAINING MICROORGANISMS; MUTATION OR GENETIC ENGINEERING; CULTURE MEDIA
  • C12N13/00—Treatment of microorganisms or enzymes with electrical or wave energy, e.g. magnetism, sonic waves
• • A—HUMAN NECESSITIES
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  • A61K—PREPARATIONS FOR MEDICAL, DENTAL OR TOILETRY PURPOSES
  • A61K9/00—Medicinal preparations characterised by special physical form
  • A61K9/0012—Galenical forms characterised by the site of application
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• • A—HUMAN NECESSITIES
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  • A61M37/00—Other apparatus for introducing media into the body; Percutany, i.e. introducing medicines into the body by diffusion through the skin
  • A61M2037/0007—Other apparatus for introducing media into the body; Percutany, i.e. introducing medicines into the body by diffusion through the skin having means for enhancing the permeation of substances through the epidermis, e.g. using suction or depression, electric or magnetic fields, sound waves or chemical agents
• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61M—DEVICES FOR INTRODUCING MEDIA INTO, OR ONTO, THE BODY; DEVICES FOR TRANSDUCING BODY MEDIA OR FOR TAKING MEDIA FROM THE BODY; DEVICES FOR PRODUCING OR ENDING SLEEP OR STUPOR
  • A61M2202/00—Special media to be introduced, removed or treated
  • A61M2202/0007—Special media to be introduced, removed or treated introduced into the body
• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
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  • A61M2205/00—General characteristics of the apparatus
  • A61M2205/05—General characteristics of the apparatus combined with other kinds of therapy
  • A61M2205/054—General characteristics of the apparatus combined with other kinds of therapy with electrotherapy
• • A—HUMAN NECESSITIES
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• • A—HUMAN NECESSITIES
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  • A61M2250/00—Specially adapted for animals

Definitions

• brain microvessels strictly regulate the transfer of substances between the blood and the brain tissue. This regulation by cerebral micro-vessels is called the blood-brain barrier (BBB), and is due to intercellular tight junctions (TJs) that form between brain capillary endothelial cells.
• BBB blood-brain barrier
• TJs proteins are expressed 50-100 times more than in peripheral microvessels. TJs are formed by an intricate complex of transmembrane proteins (claudin and occludin) with cytoplasmic accessory proteins (ZO-l and -2, cingulin, AF-6, and 7H6). By linking to the actin cytoskeleton, these proteins form a strong cell-cell connection. Brain endothelial cells, which form the endothelium of cerebral microvessels, are responsible for about 75-80% of the BBB’s resistance to substances, and other cells such as astrocytes and pericytes provide the remainder of the resistance.
• the BBB consists of tight junctions around the capillaries, and it ordinarily restricts diffusion of microscopic objects and large or hydrophilic molecules into the brain, while allowing for the diffusion of hydrophobic molecules (transcellular instead of paracellular transport).
• the BBB serves a very important function because it prevents harmful substances (e.g. bacteria, viruses, and potentially harmful large or hydrophilic molecules) from entering the brain.
• harmful substances e.g. bacteria, viruses, and potentially harmful large or hydrophilic molecules
• the action of the BBB introduces difficulties. For example, it might be desirable to deliver large or hydrophilic drug molecules to treat a disease in the patient’s brain. But when the BBB is operating normally, these drugs are blocked from entering the brain by the BBB.
• One aspect of the invention is directed to a first method for delivering a substance across a blood brain barrier of a subject’s brain.
• the relevant substance can be delivered across a blood brain barrier of a subject’s brain by applying an alternating electric field to the subject’s brain for a period of time.
• Application of the alternating electric field to the subject’s brain for the period of time increases permeability of the blood brain barrier in the subject’s brain.
• the substance is administered to the subject after the period of time has elapsed, and the increased permeability of the blood brain barrier allows the substance to cross the blood brain barrier.
• the alternating electric field is applied at a frequency between 75 kHz and 125 kHz. In some instances of the first method, the period of time is at least 24 hours. In some instances of the first method, the period of time is at least 48 hours. In some instances of the first method, the alternating electric field has a field strength of at least 1 V/cm in at least a portion of the subject’s brain. In some instances of the first method, the alternating electric field is applied at a frequency between 75 kHz and 125 kHz, the period of time is at least 24 hours, and the alternating electric field has a field strength of at least 1 V/cm in at least a portion of the subject’s brain.
• the administering of the substance is performed intravenously. In some instances of the first method, the administering of the substance is performed orally. In some instances of the first method, the subject’s brain is tumor-free.
• the substance comprises a drug for treating a disease.
• examples of these instances include a cancer treatment drug, an infectious disease treatment drug, a neurodegenerative disease treatment drug, or an auto-immune disease treatment drug, an anti-epileptic drug, a hydrocephalus drug, a stroke intervention drug, or a psychiatric drug.
• the substance is used for monitoring brain activity. Examples of these instances include a brain dye, a reporter, or a marker.
• discontinuing the application of the alternating electric field may be done to allow the blood brain barrier to recover.
• Another aspect of the invention is directed to a second method for delivering a substance across a blood brain barrier of a subject’s brain.
• the relevant substance can be delivered across a blood brain barrier of a subject’s brain by applying an alternating electric field at a first frequency to the subject’s brain for a period of time, wherein the first frequency is less than 190 kHz and the period of time is at least 24 hours, wherein application of the alternating electric field at the first frequency to the subject’s brain for the period of time increases permeability of the blood brain barrier in the subject’s brain.
• the substance is administered to the subject after the period of time has elapsed, and the increased permeability of the blood brain barrier allows the substance to cross the blood brain barrier.
• the alternating electric field is applied at a frequency between 75 kHz and 125 kHz. In some instances of the second method, the period of time is at least 48 hours. In some instances of the second method, the alternating electric field has a field strength of at least 1 V/cm in at least a portion of the subject’s brain. In some instances of the second method, the alternating electric field is applied at a frequency between 75 kHz and 125 kHz, and the alternating electric field has a field strength of at least 1 V/cm in at least a portion of the subject’s brain.
• discontinuing the application of the alternating electric field may be done to allow the blood brain barrier to recover.
• the methods described herein may be used to deliver a substance across the blood brain barrier of a subject’s whose brain is tumor free.
• another aspect of the invention is directed to a third method for delivering a substance across a blood brain barrier of a subject’s brain.
• the relevant substance can be delivered across a blood brain barrier of a subject’s brain that does not include a tumor by applying an alternating electric field at a first frequency to the subject’s brain for a period of time.
• the application of the alternating electric field at the first frequency to the subject’s brain for the period of time increases permeability of the blood brain barrier in the subject’s brain.
• the substance is administered to the subject after the period of time has elapsed, and the increased permeability of the blood brain barrier allows the substance to cross the blood brain barrier.
• the alternating electric field is applied at a frequency between 75 kHz and 125 kHz. In some instances of the third method, the period of time is at least 24 hours. In some instances of the third method, the period of time is at least 48 hours. In some instances of the third method, the alternating electric field has a field strength of at least 1 V/cm in at least a portion of the subject’s brain. In some instances of the third method, the alternating electric field is applied at a frequency between 75 kHz and 125 kHz, the period of time is at least 24 hours, and the alternating electric field has a field strength of at least 1 V/cm in at least a portion of the subject’s brain.
• discontinuing the application of the alternating electric field may be done to allow the blood brain barrier to recover.
• the methods described herein may be used to deliver a substance across the blood brain barrier of a subject with a brain tumor.
• another aspect of the invention is directed to a fourth method for treating a tumor in a subject’s brain and delivering a substance across a blood brain barrier of the subject’s brain.
• a first alternating electric field is applied at a first frequency to the subject’s brain for a first period of time.
• Application of the first alternating electric field at the first frequency to the subject’s brain for the first period of time increases permeability of the blood brain barrier in the subject’s brain.
• the substance is administered to the subject after the first period of time has elapsed, and the increased permeability of the blood brain barrier allows the substance to cross the blood brain barrier.
• a second alternating electric field at a second frequency is applied to the subject’s brain for a second period of time that is at least one week long.
• the second frequency is different from the first frequency, and the second alternating electric field at the second frequency has an intensity that is sufficiently large to inhibit the tumor.
• the first frequency is between 75 kHz and 125 kHz.
• the first frequency is between 50 kHz and 190 kHz.
• the second frequency is between 190 kHz and 210 kHz.
• the first period of time is at least 24 hours.
• the second period of time comprises a single uninterrupted interval of time that is at least one week long.
• the second period of time comprises a plurality of non-contiguous intervals of time during which the second alternating electric field at the second frequency is applied to the subject’s brain, wherein the plurality of non-contiguous intervals of time collectively add up to at least one week.
• discontinuing the application of the alternating electric field may be done to allow the blood brain barrier to recover.
• any of the methods described above is used to deliver a substance having a molecular weight of at least 4 kDa across a blood brain barrier of a subject’s brain.
• any of the methods described above is used to deliver a substance having a molecular weight of at least 69 kDa across a blood brain barrier of a subject’s brain.
• any of the methods described above is used to deliver a substance across a blood brain barrier of a subject’s brain, wherein the substance has at least one characteristic that ordinarily impedes the substance from crossing a non-leaky BBB.
• the first apparatus comprises an AC voltage generator capable of operating at a first frequency between 50 and 190 kHz and a second frequency between 50 and 500 kHz.
• the second frequency is different from the first frequency.
• the AC voltage generator has a control input, and the AC voltage generator is configured to output the first frequency when the control input is in a first state and to output the second frequency when the control input is in a second state.
• the first apparatus also comprises a controller programmed to (a) place the control input in the second state so that the AC voltage generator outputs the second frequency, (b) accept a request to switch to the first frequency, (c) upon receipt of the request, place the control input in the first state so that the AC voltage generator outputs the first frequency for an interval of time, and (d) after the interval of time has elapsed, place the control input in the second state so that the AC voltage generator outputs the second frequency.
• a controller programmed to (a) place the control input in the second state so that the AC voltage generator outputs the second frequency, (b) accept a request to switch to the first frequency, (c) upon receipt of the request, place the control input in the first state so that the AC voltage generator outputs the first frequency for an interval of time, and (d) after the interval of time has elapsed, place the control input in the second state so that the AC voltage generator outputs the second frequency.
• Some embodiments of the first apparatus further comprise a set of electrodes configured for affixation to the subject’s body; and wiring that connects an output of the AC voltage generator to the set of electrodes.
• the first frequency is between 75 kHz and 125 kHz
• the second frequency is between 150 kHz and 250 kHz.
• the interval of time is at least 24 hours. In some embodiments of the first apparatus, the interval of time is at least 72 hours.
• the controller is further programmed to, subsequent to the receipt of the request, switch the control input back and forth between the first state and the second state.
• the AC voltage generator is capable of operating at at least one additional frequency between 50 and 500 kHz, and the AC voltage generator is configured to output the at least one additional frequency when the control input is in at least one additional state, and the controller is programmed to cycle the control input through the second state and the at least one additional state prior to receipt of the request, and to cycle the control input through the second state and the at least one additional state after the interval of time has elapsed.
• the first apparatus further comprise a user interface, and the request is accepted via the user interface.
• the request is accepted via radio frequency (RF).
• RF radio frequency
• FIG. 1 depicts an exemplary setup for in vitro experiments in which imortilized murine brain capillary endothelial cells (cerebEND) were grown on coverslips and transwell inserts to create an artificial in vitro version of the BBB.
• cerebEND imortilized murine brain capillary endothelial cells
• FIGS. 2 A and 2B depict the results of integrity and permeability testing, respectively, on the artificial BBB.
• FIGS. 3 A and 3B depict data showing that the increased permeability of the artificial BBB is not caused by cell death.
• FIG. 4 depicts the positions at which rats’ brains were sliced for an in vivo experiment.
• FIG. 5 depicts the EB accumulation for this in vivo experiment in different sections of the rats’ brains.
• FIG. 6 depicts the average EB accumulation in the rat brain for this in vivo experiment, averaged over all sections.
• FIG. 7 depicts the increase in BBB permeability in three different sections of rat brains that is induced by alternating electric fields in vivo, as determined using contrast enhancement MRIs.
• FIG. 8 depicts the increase in BBB permeability in rat cortexes that is induced by alternating electric fields in vivo, as determined using contrast enhancement MRIs.
• FIG. 9 depicts a suitable timing relationship between the application of the alternating electric field and the administration of the substance to the subject.
• FIG. 10 is a block diagram of a dual -frequency apparatus that generates a first frequency for inducing BBB permeability and a second frequency for inducing cytotoxicity.
• This application describes a novel approach for temporarily increasing the permeability of the BBB using alternating electric fields so that substances that are ordinarily blocked by the BBB will be able to cross the BBB.
• FIG. 1 depicts the setup for these experiments.
• the cells were then treated with alternating electric fields (100-300 kHz) for 24 h, 48 h, and 72 h.
• the direction of the alternating electric fields was switched every 1 second between two perpendicular directions (i.e., 1 second in one direction followed by 1 second in the other direction, in a repeating sequence).
• a first set of experiments involved visualization of cell morphology and orientation, and visualization of the localization of stained proteins. This experiment was designed to ascertain how the frequency of the alternating electric field impacted the artificial BBB.
• the cells were grown on coverslips, and alternating electric fields were applied for 72 hours at four different frequencies (100 kHz, 150 kHz, 200 kHz, and 300 kHz), with a field strength of 1.7 V/cm.
• the direction of the alternating electric fields was switched every 1 second between two perpendicular directions. There was also a control in which alternating electric fields were not applied.
• Claudin 5 and ZO-l indicate the presence of an intact BBB.
• This set of cell morphology images revealed that alternating electric fields disturb the artificial BBB by delocalization of tight junction proteins from the cell boundaries to the cytoplasm, with the most dramatic effects at 100 kHz.
• a second set of experiments also involved visualization of cell morphology.
• a third set of experiments also involved visualization of cell morphology. This experiment was similar to the second set of experiments, except that the endothelial cells were grown on transwell inserts instead of coverslips. The results were similar to the results of the second set of experiments. The delocalization of TJ proteins was visible after 24 hours and the effects were most pronounced after 72 hours. The three experiments described above support the conclusion that alternating electric fields cause structural changes in the cells, which might be responsible for an increase in BBB permeability.
• FIGS. 2 A and 2B depict the results of integrity and permeability testing, respectively, on the artificial BBB after subjecting it to alternating electric fields at a frequency of 100 kHz for 72 hours (with the direction of the alternating electric fields switched every 1 second between two perpendicular directions), and for a control. More specifically, FIG. 2A depicts the results of a transendothelial electrical resistance (TEER) test, which reveals that alternating electric fields reduced the integrity of the artificial BBB to 35% of the control.
• TEER transendothelial electrical resistance
• 2B depicts the results of a fluoresceine isothiocyanate (FITC) permeability test, which reveals that the alternating electric fields increased the permeability of the artificial BBB to FITC-dextrans with a 4 kDa molecular weight to 110% of the control.
• FITC fluoresceine isothiocyanate
• FIGS. 3A and 3B depict the results of an in vitro experiment designed to determine whether the observed changes in the permeability of the artificial BBB described above might be attributable to cell death.
• This experiment tested cell division by comparing cell counts (a) when alternating electric fields were applied for 72 hours followed by no alternating electric fields for 96 hours with (b) a control in which alternating electric fields were never applied.
• Endothelial cells were grown on coverslips and treated with 100 kHz alternating electric fields at a field strength of 1.7 V/cm for 72 hours. The direction of the alternating electric fields was switched every 1 second between two perpendicular directions. The alternating electric fields were then turned off, and the cells were followed for 96 hours after stopping the alternating electric field.
• TUNEL assay for apoptosis to determine whether the observed changes in the permeability of the artificial BBB described above might be attributable to cell death.
• endothelial cells were grown on coverslips and treated with 100 kHz alternating electric fields at a field strength of 1.7 V/cm for 72 hours. The direction of the alternating electric fields was switched every 1 second between two perpendicular directions. In the control, alternating electric fields were not applied.
• Cell morphology images depicting apoptosis (TUNEL) and Nuclei (DAPI) were obtained after 24, 48, and 72 hours. None of those images revealed additional evidence of apoptosis, indicating that alternating electric fields did not cause cell death. This confirms that the changes in the BBB permeability noted above were not attributable to cell death.
• EB dye is an azo dye that has a very high affinity for serum albumin (molecule size ⁇ 69 kDa). Because of its large molecule size, serum albumin will ordinarily not be able to get past the BBB. But if the permeability of the BBB has been sufficiently increased, some of the serum albumin molecules (together with the EB dye that has been bound thereto) will make it across the BBB and can then be detected by looking for the EB in the rat’s brain.
• EB Evans Blue
• EB was injected intravenously into the tail vein under anesthesia (Once injected, EB immediately binds to Albumin), and the EB was allowed to circulate for 2 hours in all cases.
• the following steps were then performed: (a) intracardiac perfusion with saline; (b) brains are sliced in four pieces with a brain sheer; (c) pieces were photographed to localize staining and weighted; (d) EB extraction after tissue homogenization with TCA 50% (1 :3) and centrifuge and (e) EB quantification at 610 nm. Results are given as pg EB per g tissue.
• the rats’ brains were sliced into four pieces using a brain sheer at the positions shown in FIG. 4. EB accumulation in these four specific sections was then measured. In addition, a computer simulation was performed to determine the field strength in each of these four sections. Table 2 specifies the field strength obtained from the simulation in each of these four sections, with ah values given in V/cm RMS.
• FIG. 6 depicts the average EB accumulation in the rat brain, averaged over all four sections 1-4. This result reveals higher accumulation of EB in the brains of rats treated with alternating electric fields for 72 hours, and this result was statistically significant (p ⁇ 0.05).
• the resulting images revealed significantly higher levels of accumulation of the fluorescent 4 kDA TRITC-Dextran in the brain tissue of the rats that were subjected to alternating electric fields (as compared to the control), confirming yet again that alternating electric fields increase the permeability of the BBB.
• Enhanced MRI with intravenous injection of Gadolinium contrast agent (Gd- DTPA, Magnetol, MW 547).
• Gadolinium contrast agent Gadolinium contrast agent
• test rats were treated with 100 kHz alternating electric fields for 72 h, and control rats were not treated with alternating electric fields for the same period of time. After this 72 h period, the alternating electric field was turned off, the rats were anesthetized, and a series of 60 Tlw MRI scans (each of the scans having a duration of 28 seconds) was acquired. The gadolinium contrast agent was injected into the rat’s tail vein during the 7th of these 60 scans.
• the image analysis for each rat included (1) determining a baseline for each voxel by calculating the mean of the first six Tlw MRI scans for each voxel (i.e., the scans prior to the injection of the gadolinium); (2) computing voxel by voxel, the percent signal change (i.e., gadolinium accumulation) over time relative to the baseline; (3) segmenting the brain into anterior, middle, and posterior segments; (4) generating for each of the three segments the mean percent signal change with respect to the baseline over all the voxels in the respective segment and then (5) averaging 4 consecutive time points (i.e. 4 scans) together. Finally, the data from all of the rats within any given group were averaged together.
• a paired t test was used to compare between the two groups, and pO.OOOl.
• the upper size limit of molecules that can pass through the BBB after applying the alternating electric fields has not yet been determined. But based on (a) the in vitro experiments described herein using FITC-dextrans with a 4 kDa molecular weight and (b) the in vivo experiments described herein using EB (which binds to serum albumin having a molecule size of - 69 kDa), the upper limit appears to be at least about 69 kDa, and is most certainly at least 4 kDa.
• Examples include but are not limited to the following: delivering
• chemotherapeutic agents across the BBB to treat cancer in this context, it may be possible to lower the dosage of drugs for the treatment of brain tumors and metastases with severe side effects in other parts of the body based on the increased permeability of the drugs to the brain); delivering antibodies and/or cell-based therapies across the BBB for immunotherapy; delivering contrast agents dyes, reporters, and markers across the BBB for diagnostic purposes and for research (e.g.
• monitoring brain activity delivering antibacterial agents across the BBB to treat infectious diseases; delivering anti-viral agents or virus neutralizing antibodies across the BBB to treat viral infections; delivering anti-parasitic agents across the BBB to treat parasites; delivering agents to treat neurodegenerative and autoimmune disease across the BBB; delivering psychiatric drugs; delivering anti-epileptic drugs; delivering hydrocephalus drugs; delivering stroke intervention and recovery drugs; delivering compounds that are lacking in the brain across the BBB to treat conditions in which those compounds are lacking (e.g., for treating Parkinson’s disease, etc.).
• the methods described herein can also be applied in the in vivo context by applying the alternating electric fields to a live subject’s brain. Imposing the electric field in the subject’s brain will increase the permeability of the BBB, which will enable molecules that are ordinarily blocked or impeded by the BBB to get through. This may be
• Electrodes are on or below the subject’s skin so that application of an AC voltage between selected subsets of those electrodes will impose the alternating electric fields in the subject’s brain.
• one pair of electrodes could be positioned on the front and back of the subject’s head, and a second pair of electrodes could be positioned on the right and left sides of the subject’s head.
• the electrodes are capacitively coupled to the subject’s body (e.g., by using electrodes that include a conductive plate and also have a dielectric layer disposed between the conductive plate and the subject’s body). But in alternative embodiments, the dielectric layer may be omitted, in which case the conductive plates would make direct contact with the subject’s body. In another embodiment, electrodes could be inserted subcutaneously below a patent’s skin.
• An AC voltage generator applies an AC voltage at a selected frequency (e.g.,
• the AC voltage generator applies an AC voltage at the same frequency (or a different frequency) between the front and back electrodes for a second period of time (e.g. 1 second), which induces alternating electric fields where the most significant components of the field lines are parallel to the sagittal axis of the subject’s head.
• This two step sequence is then repeated for the duration of the treatment.
• thermal sensors may be included at the electrodes, and the AC voltage generator can be configured to decrease the amplitude of the AC voltages that are applied to the electrodes if the sensed temperature at the electrodes gets too high.
• one or more additional pairs of electrodes may be added and included in the sequence.
• only a single pair of electrodes is used, in which case the direction of the field lines is not switched.
• any of the parameters for this in vivo embodiment e.g., frequency, field strength, duration, direction-switching rate, and the placement of the electrodes
• a wide variety of applications for increasing the permeability of the BBB can be readily envisioned in the in vivo context.
• localized enhancement of drug uptake by tumor cells e.g., glioblastoma cells
• a period of time e.g., 72 hours or at least 24 hours
• FIG. 9 depicts a suitable relationship in timing between the application of the alternating electric field and the administration of the substance to a live patient.
• the permeability of the BBB will begin to increase before the substance is administered and before the substance reaches the BBB. This will enable the substance to cross the BBB immediately upon its arrival.
• the intervals of time discussed above in connection with FIG. 9 can either be uninterrupted or can include breaks that are preferably short.
• a 12 hour interval could be satisfied by a single uninterrupted block of 12 hours.
• the 12 hour interval could be satisfied by applying the alternating electric fields for 6 hours, followed by a 1 hour break, followed by applying the alternating electric fields for an additional 6 hours.
• Similar breaks may also optionally interrupt the 72 hour interval that precedes the administration of the substance.
• the administration of the substance may be performed using any of a variety of approaches including but not limited to intravenously, orally, subcutaneously, intrathecal, intraventricularly, and intraperitonealy.
• the frequency of the alternating electric fields is less than 190 kHz (e.g., between 50 and 190 kHz or between 25 and 190 kHz). Based on the experiments discussed above, using a frequency of less than 190 kHz combined with a period of time of at least 24 hours will increase the change in permeability (as compared to operating outside of those ranges).
• the methods described herein may be used to deliver a substance across the blood brain barrier of a subject’s brain when the subject’s brain includes a tumor.
• One existing approach to treating brain tumors is by applying alternating electric fields at frequencies between 50 and 500 kHz, preferably between 100 and 300 kHz to the tumor. For glioblastoma, 200 kHz is the most preferred frequency. Alternating electric fields at these frequencies are referred to as TTFields, and are described in US patents 6,868,289 and 7,565,205, each of which is incorporated herein by reference in its entirety. Briefly, those two applications describe disrupting dividing cells during mitosis.
• TTFields The effectiveness of TTFields is improved when the direction of the electric field is periodically switched, when the strength of the field in at least a portion of the tumor is at least 1 V/cm, and when the fields are applied for long periods of time (e.g., weeks or months) with as few breaks as possible.
• TTFields In patients with brain tumors, situations may arise where it will be desirable to treat the tumor with TTFields and also deliver a substance across the same patient’s blood brain barrier (e.g., to help get a therapeutically effective amount of a chemotherapy drug past the BBB to provide an additional line of attack against the tumor).
• a single frequency of an alternating electric field it may be possible to use a single frequency of an alternating electric field to both treat the tumor and increase the permeability of the BBB.
• alternating electric fields with different frequencies: a first frequency that is selected to provide improved results for increasing the permeability of the BBB, and a second frequency that is selected to provide improved results for the anti-tumor action of the TTFields.
• FIG. 10 is a block diagram of an apparatus that generates a first frequency for inducing BBB permeability and a second frequency for inducing cytotoxicity.
• the apparatus includes an AC voltage generator 44 that is similar to the conventional Optune® field generator unit, but has the ability to operate at two different frequencies.
• the first frequency is between 50 and 190 kHz and the second frequency is between 50 and 500 kHz. In some embodiments, the first frequency is between 75 kHz and 125 kHz and the second frequency is between 150 kHz and 250 kHz.
• the ability to operate at two different frequencies may be implemented, for example, using relays to switch either a first set of components or a second set of components into the conventional circuit that generates the AC voltage, and adjusting the operating frequency of an oscillator.
• the AC voltage generator 44 is configured to output either the first frequency or the second frequency depending on the state of a control input. When the control input is in a first state the AC voltage generator 44 outputs the first frequency, and when the control input is in a second state the AC voltage generator 44 outputs the second frequency.
• a controller 42 is programmed to place the control input in the second state so that the AC voltage generator 44 outputs the second frequency.
• the controller 42 is also programmed to accept a request to switch to the first frequency. In the embodiment depicted in FIG.
• the request arrives via a user interface 40 that may be implemented using any of a variety of conventional approaches including but not limited to a pushbutton, a touch screen, etc.
• the request may arrive via RF (e.g. Bluetooth, WiFi, etc.) from a tablet, smartphone, etc.
• RF e.g. Bluetooth, WiFi, etc.
• the controller 42 Upon receipt of the request, the controller 42 will place the control input in the first state so that the AC voltage generator 44 will output the first frequency for an interval of time (e.g., 72 hours). After the interval of time has elapsed, the controller 42 will place the control input in the second state so that the AC voltage generator 44 reverts to outputting the second frequency.
• an interval of time e.g. 72 hours
• the AC voltage generator 44 may be configured to output one or more additional frequencies (e.g., a third frequency, a fourth frequency, etc.), depending on the state of the control input. Preferably each of these additional frequencies is selected to induce cytotoxicity.
• the controller 42 is programmed to cycle the control input through the states that cause the AC voltage generator 44 to output the second frequency and the one or more additional frequencies before the request arrives.
• the controller 42 is also programmed to accept a request to switch to the first frequency. Upon receipt of the request, the controller 42 will place the control input in the first state so that the AC voltage generator 44 will output the first frequency for an interval of time (e.g., 72 hours). After the interval of time has elapsed, the controller 42 will revert to cycling the control input through the states that cause the AC voltage generator 44 to output the second frequency and the one or more additional frequencies.
• the system depicted in FIG. 10 is particularly useful when a person has a tumor that is being treated by combination therapy that includes TTFields and chemotherapy.
• the system operates most of the time at the second frequency to provide the maximum cytotoxicity effect.
• healthcare personnel or the user actuates the user interface 40 to switch the system to the first frequency that promotes BBB permeability.
• the actuation of the user interface could be done e.g., 72 hours before the expected start of the
• the controller 42 can control the control input so that the AC voltage generator 44 will output the first frequency for an interval of time (e.g., 1 hour), then switch back and forth between the second frequency and the first frequency (e.g., switching every hour).
• the controller 42 controls the control input so that the AC voltage generator 44 reverts to outputting the second frequency.
• a set of electrodes (not shown) that are similar to the conventional electrodes used with Optune® are connected to the output of the AC voltage generator 44.
• the BBB should recover to its original low-permeability state after a sufficient amount of time has elapsed following the termination of the alternating electric field. This can be important in many contexts for the safety of the subject.

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