Reducing motility of cancer cells using tumor treating fields (TTFields)
The spreading of cancer cells in a target region can be inhibited by imposing a first AC electric field in the target region for a first interval of time, with a frequency and amplitude selected to disrupt mitosis of the cancer cells; and imposing a second AC electric field in the target region for a second interval of time, with a frequency and the amplitude selected to reduce motility of the cancer cells. The amplitude of the second AC electric field is lower than the amplitude of the first AC electric field.
1. A method of inhibiting spreading of cancer cells in a target region, the method comprising:
(a) imposing a first AC electric field in the target region for a first interval of time, the first AC electric field having a first frequency and a first amplitude, wherein the first frequency and the first amplitude are selected so that the first AC electric field disrupts mitosis of the cancer cells;
(b) imposing a second AC electric field in the target region for a second interval of time, the second AC electric field having a second frequency and a second amplitude, wherein the second frequency and the second amplitude are selected so that the second AC electric field reduces motility of the cancer cells, and wherein the second amplitude is lower than the first amplitude; and
(c) continuously repeating step (a) and step (b) in an alternating sequence during a course of treatment.
2. The method of claim 1 , wherein the second amplitude is less than 75% of the first amplitude.
3. The method of claim 2 , wherein the first interval of time is less than 5 seconds, and wherein the second interval of time is less than 5 seconds.
4. The method of claim 3 , wherein the course of treatment has a duration of at least 12 hours.
5. The method of claim 1 , wherein the second frequency and the first frequency are different.
6. The method of claim 1 , wherein the first frequency is 200 kHz±10% and the second frequency is 300 kHz±10%.
7. The method of claim 1 , further comprising a step of administering a compound that inhibits cell mobility during the course of treatment.
8. The method of claim 7 , wherein the compound comprises Bumetanide.
9. The method of claim 1 , wherein the second amplitude is at least 0.6 V/cm RMS.
10. The method of claim 1 , wherein the second amplitude is less than 75% of the first amplitude, wherein the second frequency and the first frequency are different, wherein the first interval of time is less than 5 seconds, wherein the second interval of time is less than 5 seconds, and wherein the second amplitude is at least 0.6 V/cm RMS.
11. The method of claim 10 , wherein the first frequency is 200 kHz±10% and the second frequency is 300 kHz±10%.
12. The method of claim 1 , wherein the first AC electric field is imposed in the target region in a first direction for a first portion of the first interval of time,
wherein the first AC electric field is imposed in the target region in a second direction for a second portion of the first interval of time, and
wherein an angle between the first direction and the second direction is between 60° and 90°.
13. The method of claim 12 , wherein the second AC electric field is imposed in the target region in the first direction for a first portion of the second interval of time, and
wherein the second AC electric field is imposed in the target region in the second direction for a second portion of the second interval of time.
14. The method of claim 13 , wherein the second amplitude is less than 75% of the first amplitude.
15. The method of claim 14 , wherein the second frequency and the first frequency are different, wherein the first interval of time is less than 5 seconds, and wherein the second interval of time is less than 5 seconds.
16. The method of claim 1 , wherein a direction of the first AC electric field is changed during at least some of the repeating steps, and wherein a direction of the second AC electric field is changed during at least some of the repeating steps.
17. The method of claim 16 , wherein the second amplitude is less than 75% of the first amplitude.
18. The method of claim 17 , wherein the second frequency and the first frequency are different, wherein the first interval of time is less than 5 seconds, and wherein the second interval of time is less than 5 seconds.
19. An apparatus for inhibiting spreading of cancer cells in a target region, the apparatus comprising:
an AC signal generator having (i) a first controllable output configured to apply an AC voltage across a first set of capacitively coupled electrodes that are positioned in a vicinity of the target region, so as to impose an electric field in the target region in a first direction and (ii) a second controllable output configured to apply an AC voltage across a second set of capacitively coupled electrodes that are positioned in the vicinity of the target region, so as to impose an electric field in the target region in a second direction; and
a controller configured to (a) control the first controllable output so that a first AC signal is generated for a first interval of time, the first AC signal having a first frequency and a first amplitude, wherein the first frequency and the first amplitude are selected to impose an electric field that disrupts mitosis of the cancer cells, and (b) control the first controllable output so that a second AC signal is generated for a second interval of time, the second AC signal having a second frequency and a second amplitude, wherein the second frequency and the second amplitude are selected to impose an electric field that reduces motility of the cancer cells, and wherein the second amplitude is lower than the first amplitude, (c) control the second controllable output so that a third AC signal is generated for a third interval of time, the third AC signal having a third frequency and a third amplitude, wherein the third frequency and the third amplitude are selected to impose an electric field that disrupts mitosis of the cancer cells, and (d) control the second controllable output so that a fourth AC signal is generated for a fourth interval of time, the fourth AC signal having a fourth frequency and a fourth amplitude, wherein the fourth frequency and the fourth amplitude are selected to impose an electric field that reduces motility of the cancer cells, and wherein the fourth amplitude is lower than the third amplitude, and (e) continuously repeat (a) through (d) in an alternating sequence during a course of treatment.
20. The apparatus of claim 19 , wherein the second amplitude is less than 75% of the first amplitude and wherein the fourth amplitude is less than 75% of the third amplitude.
21. The apparatus of claim 19 , wherein the second frequency and the first frequency are different, and wherein the fourth frequency and the third frequency are different.
22. The apparatus of claim 19 , wherein the second amplitude is less than 75% of the first amplitude and wherein the fourth amplitude is less than 75% of the third amplitude, wherein the second frequency and the first frequency are different, wherein the fourth frequency and the third frequency are different, wherein the third frequency is the same as the first frequency, wherein the fourth frequency is the same as the second frequency, wherein the first interval of time is less than 5 seconds, wherein the second interval of time is less than 5 seconds, wherein the third interval of time is less than 5 seconds, and wherein the fourth interval of time is less than 5 seconds.
23. The apparatus of claim 19 , wherein the first frequency is 200 kHz±10%, the second frequency is 300 kHz±10%, the third frequency is 200 kHz±10%, and the fourth frequency is 300 kHz±10%.