SYSTEM FOR TREATING A TUMOUR

Technical field

This invention relates to a system for treating a tumour and to a method for controlling the system.

The field of this invention is that of medical systems or devices for treating tumours.

Background art Known in this field are systems that use ionizing radiations, such as, for example, the systems described in patent documents US5527352A and US5718246A. Radiotherapy can, however, have serious side effects on account of the high radiation doses; for example, if used to treat brain tumours, it may cause serious cognitive impairments. Also known are systems that use ultrashort electric pulses. More specifically, in some known systems for implementing a therapy known as electrochemotherapy (ECT), tumour cells are treated with pulsed electric fields in combination with chemotherapy drugs to destroy the tumour. Also known are systems for implementing a therapy known as irreversible electroporation (IRE) in which the tumour is destroyed by the high doses of electromagnetic energy applied to the tissues. Examples of these systems or methods for treating a tumour with ultrashort electric pulses are described in the following patent documents: US8512334B2, US9943684B2, US201 90299019A1 , WO2014/197240 A2, WO201 5/175570.

In addition, the application of a pulsed electric field in combination with simultaneous irradiation with ionizing radiation is known from patent document R0118847B1 .

A widespread need in this technical field is that of having treatment systems and methods that offer the maximum effectiveness in killing the tumour cells (and inhibiting their cell division) and that can, at the same time, safeguard healthy cells and preserve the surrounding tissues as much as possible. This need is felt particularly strongly in the field of the treatment of cancer stem cells (CSC), which is a restricted cell population present in most tumours and which constitutes a source for cancer maintenance and progression.

Furthermore, patent document W02020/061192A discloses a medical diagnostic system comprising an electrical pulse generator; in this document, after the treatment with electrical impulses, after days or months, a chemotherapy or radiotherapy treatment is applied. The W02020/061192A system is configured for the treatment of a generic tumor and activation of the immune system. This system has several disadvantages. First of all, it makes it necessary for the patient to undergo several sessions (at least one session for the administration of electrical impulses and one session for chemotherapy or radiotherapy), thus making the treatment long and complex. Furthermore, it is completely silent and does not provide any indication regarding a possible reduction in the radiation dose and related side effects.

Disclosure of the Invention This invention has for an aim to provide a system and a method for controlling the system to overcome the above mentioned disadvantages of the prior art.

This aim is fully achieved by the system and method of this disclosure as characterized in the appended claims. According to an aspect of it, this disclosure relates to a system for treating a tumour. In particular, the system object of the present description is configured for the treatment of tumor stem cells. The system comprises a pulsed electric field generator, configured to emit electric pulses (specifically ultrashort electric pulses) directed at a zone of a human body to be treated. Preferably, the system also comprises an ionizing radiation generator, configured to emit ionizing rays directed at the zone of the human body to be treated. Thus, the system of this disclosure allows treating tumours with a combination of (ultrashort) electric pulses and ionizing radiation.

Preferably, the system comprises a timer (or counter, or chronometer or clock) configured to count the time.

The system comprises a control unit. The control unit is connected to the pulsed electric field generator; preferably, the control unit is also connected to the timer. In an embodiment, the control unit is connected to the ionizing radiation generator. The control unit is programmed to activate the pulsed electric field generator to emit an electric pulse train. After the electric pulse train has been emitted, the control unit is programmed to stop the pulsed electric field generator and to start the timer for counting a predetermined length of time. After the predetermined length of time has elapsed, the control unit is programmed to provide an information item for activating the ionizing radiation generator.

In an embodiment, the information item for activating the ionizing radiation generator may be communicated to a user to help them manage the system and prompt them to activate the ionizing radiation generator. In fact, tumor cells (in particular, tumor stem cells) are made more vulnerable to the action of ionizing radiation after said predefined period of time has elapsed from the administration of pulsed electric fields. In other words, the administration of pulsed electric fields makes the ionizing radiation, applied at a distance of said predetermined time, more effective in attacking cancer cells.

In this embodiment, the system comprises an output interface, configured to provide a user with the information item for activating the ionizing radiation generator. The output interface may, for example, include a screen on which the predetermined length of time (for example, 3 hours) is displayed. The output interface might be configured to emit a signal (a light, sound, vibration or other signal) when the predetermined length of time has elapsed, to warn the user that it is time to activate the ionizing radiation generator.

In another embodiment, the information item for activating the ionizing radiation generator may be transmitted to the ionizing radiation generator to instruct it to emit a dose of ionizing radiation. Thus, in this embodiment, the control unit is configured to issue a command to activate the ionizing radiation generator when the predetermined length of time has elapsed. The system may comprise an input interface configured to receive an input information item from a user and a value of the predetermined length of time can be set by the control unit as a function of the input information item. For example, the input information item might itself include the predetermined length of time. In an embodiment, the system comprises a database containing a plurality of records, each of which includes a treatment time associated with a type of tumour. Besides the type of tumour, the record might include information such as the patient’s age, the state of progression and propagation of the tumour, previous treatments performed on the same tumour and/or on the same patient. Thus, for each type of tumour, the database might include more than one record, hence more than one recommended treatment time depending on other factors, such as those listed above. In this embodiment, the input information item represents a type of tumour to be treated (and, if necessary, other information such as the patient’s age, the state of progression and propagation of the tumour, previous treatments performed on the same tumour and/or on the same patient). The control unit is configured to query the database as a function of the input information item, to retrieve the treatment time (specifically, the input time associated with the type of tumour to be treated and with other factors stored in the database), and is also configured to set the treatment time retrieved from the database as a value for the predetermined length of time. The control unit may also retrieve a plurality of times from the database and calculate (for example, through a weighted average) the value to be set for the predetermined length of time. For example, if the database includes a first record containing a first recommended treatment time for a certain type of tumour in patients of a first chronological age, and a second record containing a second recommended treatment time for the same type of tumour in patients of a second chronological age, the control unit can process these data to generate an output information item representing a third recommended treatment time for the same type of tumour in patients of a third chronological age included between the first chronological age and the second chronological age. The fact of waiting for a predetermined length of time between the application of the pulsed electric fields and the application of the ionizing radiation is of fundamental importance for the efficacy of the treatment, that is to say, for radiosensitizing the cancer cells so that they can be effectively destroyed by applying the ionizing radiation. In effect, if too little time passes between the application of the pulsed electric fields and the application of the ionizing radiation, the biological response to the pulsed electrical fields is not optimum radiosensitization and the treatment therefore has little effect. Conversely, if too much time passes between the application of the pulsed electric fields and the application of the ionizing radiation, their combined effect is diminished on account of greater cell recovery and, in this case, too, the efficacy of the treatment is lowered. Preferably, the predetermined length of time is between 1 h and 15 h. More specifically, the predetermined length of time for treating cancer stem cells is between 2 h and 6 h or between 2 h and 4 h; preferably, it is 3 h. For other types of tumour, the predetermined length of time might be longer, for example, between 7 and 10 h or between 9 and 12 h. It should be noted that this predetermined period of time is short enough to allow the administration of electrical impulses and radiotherapy in a single session, without the need to operate several separate sessions on the patient.

Preferably, the number of electric pulses of the pulse train is low compared to prior art treatments; for example, the pulse train includes a number of electric pulses between 3 and 10, or between 4 and 7 or between 4 and 6. Preferably, the pulse train includes 5 pulses. It is stressed that the number of pulses cannot be reduced below a minimum threshold (for example, 3 or 4), being the minimum level for the appearance of the biological response; and what is more, to limit the possible thermal effects that can damage the surrounding tissues, this value cannot be increased indiscriminately.

Preferably, each electric pulse of the pulse train has an amplitude (that is, an electric field) of between 0.1 MV/m and 0.5MV/m, and more preferably, between 0.2 MV/m and 0.4MV/m or between 0.25 MV/m and 0.35 MV/m (for example, 0.3 MV/m).

Preferably, the pulse train has an energy per unit volume (or energy density) of between 4 and 70 MJ/m ³ , or between 10 and 60, or between 20 and 50 (for example, 30 MJ/m ³ ). Preferably, each electric pulse of the pulse train has an energy density of between 1 and 2 MJ/m ³ (for example, 1.5 MJ/m ³ ).

It should be noted that the energy, the energy density, that is to say, the energy applied per unit volume (calculated as W=σx(TxDCxNI)xE2 is measured in J/m ³ , where W is the energy density, σ the conductivity of the medium (S/m) to which the electric pulses are applied, σ the period of the signal (s), DC the duty cycle of the signal expressed as a percentage, Nl the number of pulses applied and E the electric field applied (V/m).

Each electric pulse may have an exponential shape or a square shape or other shapes. The duration considered for each pulse was 50% of the peak value.

The frequency of the electric pulses of the pulse train is preferably between 0.8 and 1 .2 Hz., for example, 1 Hz.

The duration of each electric pulse of the pulse train is preferably between 20 and 60 μs, or between 30 and 50 μs, or between 35 and 45 μs; for example, 40 μs. It should be noted that the duration of the pulses might be even lower, for example in the order of tens of nanoseconds or picoseconds, or longer, for example, in the order of milliseconds. Preferably, the ionizing rays are X-rays. The dose applied (in a single application) is preferably less than 10 Gy, or less than 8 Gy, or less than 6 Gy, or less than 5 Gy; more specifically, it may be between 1 Gy and 4 Gy, or between 1 Gy and 3 Gy (for example, 2 Gy). This dose is low compared to many prior art systems and therefore has a lower impact on the surrounding tissues.

In fact, the administration of pulsed electric fields makes the subsequent radiotherapy more effective, even with reduced doses of radiation imparted.

This disclosure also provides a method for controlling a system for treating a tumour (preferably, for treating cancer stem cells, specifically medulloblastoma). It should be noted that cancer stem cells are a subpopulation of cancer cells, usually resistant to radiotherapy and chemotherapy.

The system is a system according to one or more aspects of this disclosure. The method comprises a step of activating the pulsed electric field generator to emit an electric pulse train. After emitting the electric pulse train, the method comprises a step of stopping the pulsed electric field generator. At the same time, the method comprises a step of starting a timer for counting a predetermined length of time. After the predetermined length of time has elapsed, the method comprises a step of providing an information item for activating the ionizing radiation generator. In an embodiment, the information item for activating the ionizing radiation generator is supplied to the user through an output interface; that way, the user knows when to activate the ionizing radiation generator. In an embodiment, the information item for activating the ionizing radiation generator might be a command issued by the control unit to activate the ionizing radiation generator.

In an embodiment, the method comprises a step of receiving an input information item representing a type of tumour to be treated, and a step of querying a database as a function of the input information item to retrieve the treatment time associated with the type of tumour to be treated. The database contains a plurality of records, each of which includes a treatment time associated with a type of tumour. The method then comprises a step of setting the treatment time retrieved from the database as the value for the predetermined length of time.

It should be noted that the electric pulse train is a pulse train according to one or more of the aspects of this disclosure; more specifically, it includes a number of electric pulses between 3 and 10, or between 4 and 7 or between 4 and 6 (preferably, the pulse train includes 5 pulses).

This disclosure also provides a computer program comprising operating instructions configured to perform the steps of the method for controlling a system for treating a tumour according to one or more aspects of this disclosure.

This disclosure also provides a method for treating a tumour. More specifically, the method comprises treating cancer stem cells; still more specifically, the method comprises treating cancer stem cells of a medulloblastoma. The method for treating the tumour (or cancer stem cells) comprises a step of placing a pulsed electric field generator in the proximity of a zone of a human body to be treated, and a step of emitting a train of electric pulses with the pulsed electric field generator (the pulses being pulses according to one or more of the aspects of this disclosure). The method for treating the tumour also includes a step of placing an ionizing radiation generator in the proximity of the zone of the human body to be treated, and a step of emitting a dose of ionizing radiation with the ionizing radiation generator. The step of emitting the ionizing radiation is carried out after the step of emitting the electric pulses. More specifically, the step of emitting the ionizing radiation is carried out when a predetermined length of time from the step of emitting the electric pulse train has elapsed. The predetermined length of time is between 1 h and 15 h, or between 2 h and 6 h, or between 2 h and 4 h; preferably, it is substantially equal to 3 h.

Brief descriDtion of the drawings These and other features will become more apparent from the following description of a preferred embodiment, illustrated by way of non-limiting example in the accompanying drawings, in which:

- Figure 1 represents a system for treating a tumour according to one or more aspects of this disclosure; - Figure 2 shows a pulsed electric field applicator of the system of Figure

1;

- Figures 3-12 show the results of experiments conducted using the system of this disclosure for the treatment of cancer stem cells;

- Figure 13 shows an electric pulse profile of the pulse train emitted by the pulsed electric field generator of Figure 2.

Detailed description of preferred embodiments of the Invention

With reference to the accompanying drawings, the numeral 1 denotes a system for treating a tumour. The system 1 comprises a pulsed electric field generator 2 and an ionizing radiation generator 3. The system 1 comprises a control unit 4. The control unit 4 is configured to control the pulsed electric field generator 2 and, in an embodiment, the ionizing radiation generator 3.

The accompanying drawings show the results of the experimental tests conducted. More specifically, the experimental tests were conducted on a human medulloblastoma cell line (D283 Med ATCC®) characterized by a high percentage (greater than 95%) with stem cell phenotype. Besides these cells, which were considered as an example of medulloblastoma cancer stem cells (CSC), non-tumoral human brain cells, specifically astrocytes (NHA Lonza, Catalog #: CC-2565) were also exposed to the treatment to check the selectivity of the treatment, that is to say, to check the whether the treatment was effective in destroying the tumour cells without affecting the non-tumoral cells.

Figures 3-9 show the results of applying a train of 5 electric pulses of exponential shape (that is, the shape illustrated in Figure 13) having an amplitude of 0.3 MV/m and a duration of 40 μs each; this electric pulse train is hereinafter denoted by the label CE5-40.

A first result, represented in Figure 3, showed that approximately 80% of the D283 cells were permeabilized after exposure (after 3 h). In effect, the electric pulses cause the migration of the electric charges in the cancer cells and modify the orientation of the dipolar molecules, causing an increase in the transmembrane potential. This polarization results in structural defects in the plasma membranes, which thus become more permeable. The NHA cells, on the other hand, do not undergo any substantial change in their permeability after 3 hours because it would be necessary to induce a higher transmembrane potential in these cells to produce significant structural defects.

In line with this result, a high cell death rate (assessed with trypan blue) was found in the D283 cells and not in the NHA cells at all the times examined (Figure 4). Furthermore, exposure to CE5-40 induced a statistically significant block in cell proliferation of both cell lines but in the D283 cells with an efficacy 6.9 times higher at 24 hours from exposure and 8.2 times higher after 48 hours (Figure 5) compared to the NHA cells (Figure 6).

These results show that the application of CE5-40 acts selectively on the CSCs, without damaging the healthy cells (NHA).

Following these results, the state of the cell cycle was analysed 24 hours after exposure using the cytofluorimetric method (propidium iodide staining). The results revealed, in the group of cells exposed to CE5-40, a significant decrease of the G0/G1 phase of the cell cycle and a significant increase of the Sub-G1 and G2/M phase, compared to the group of cells that was not exposed, denoted as “SHAM”; this suggests the induction of significant cell death levels and G2/M phase arrest in the surviving cells (as shown in Figure 7). No perturbation was, however, revealed in the NHA cell cycle (as shown in Figure 8).

To identify the molecular mechanisms behind this different response, the expression profile of the genes involved in the cell cycle 24 hours after exposure was analysed using the Human Cell Cycle RT2 Profiler PCR Array tool. Bioinformatic analysis, namely Signaling Pathway Impact Analysis (SPIA), showed that the GADD45a gene is highly involved in the G2/M arrest and plays a key role in inducing apoptosis and senescence. Moreover, a protein expression analysis (western blot), the results of which are given in Figure 9, which shows the analysis of the proteins in the D283 cells without treatment and after 3 hours and 24 hours from treatment with CE5-40, confirmed that the GADD45a gene mediates the biological processes after caspase-3 and p15 and p16 activation. Figures 10-11 show the results of in vitro tests on CSCs, involving exposure to ionizing radiation (X-rays in increasing doses of 2, 5 and 8 Gy) following application of CE5-40.

More specifically, Figure 10 shows an image representing the results of a clonogenic test for the D283 line rich in CSCs; Figure 11 shows the reduction of clones following treatment with CE5-40 and exposure to increasing doses of ionizing radiation, compared with the reduction of clones following exposure to the same doses of ionizing radiation of “SHAM” cells, that is, cells not previously exposed to CE5-40. These results show the efficacy of combining the two treatments, namely the pulsed electric field and ionizing radiation treatments. In particular, application of pulsed electric fields allows obtaining a significant reduction of clones even at not too high doses of ionizing radiation. For example, combining CE5-40 with 2 Gy is as efficacious as applying 5 Gy without applying CE5-40. Thus, these tests show that the application of CE5-40 has a radiosensitizing effect on the CSCs.

Figure 12 shows the results of in vivo tests on CSCs, involving exposure to ionizing radiation (X-rays in increasing doses of 2, 5 and 8 Gy) following application of CE5-40. For this purpose, the cells pretreated with electric pulses were inoculated into the sides of CD1 nu/nu mice and the inoculation site was irradiated 3 hours after inoculation. Tumour growth was monitored for 43 days. More specifically, Figure 12 shows the tumour growth curves in D283 SHAM (untreated) cells, in D283 cells treated with CE5-40 but not with X-rays, in D283 cells treated with a 5 Gy dose of X- rays but not with CE5-40 and, lastly, in D283 cells treated with CE5-40 and with a 2 Gy dose of X-rays. It is noted that the combined action of electric pulses and X-rays in a dose of 2 Gy is more efficacious not only than treatment just with CE5-40 pulses but also than treatment just with X- rays in a dose of 5 Gy. The results of Figure 12 thus show a significant reduction in tumour growth using a combined treatment with CE5-40 followed by a 2 Gy dose of X-rays, preferably applied approximately 3 hours after the electric pulse treatment. This result shows that the electric pulses are capable of acting as radiosensitizing agent by selectively altering the physiology of the CSCs and thus enhancing the response of the CSCs to the X-rays. Thus, the application of electric pulses combined with the subsequent application of ionizing radiation allows obtaining efficacious results even with reduced doses of radiation, hence limiting the side effects.