Targeted hysteresis hyperthermia as a method for treating diseased tissue

• US 6,167,313 A
• Filed: 11/09/1998
• Issued: 12/26/2000
• Est. Priority Date: 05/10/1996
• Status: Expired due to Term

• Current Assignee: Sirtex Medical Limited
• Original Assignee: Sirtex Medical Limited
• Inventors: Gray, Bruce Nathaniel, Jones, Stephen Keith
• Primary Examiner(s): Dvorak, Linda C. M.
• Assistant Examiner(s): Ruddy, David M.
• Application Number:
  US09/180,399
• Time in Patent Office: 778 Days
• Field of Search: 607/100-104, 600/9-12
• US Class Current: 607/103
• CPC Class Codes: A61K 41/0052 Thermotherapy; Hyperthermia; Magnetic induction; Induction heating therapy
• CPC Class Codes: A61K 9/5094 Microcapsules containing magnetic carrier material, e.g. ferrite for drug targeting
• CPC Class Codes: A61N 1/406 using implantable thermoseeds or injected particles for localized hyperthermia preparations of seeds and particles A61K41/0052

Abstract

A method for site specific treatment of diseased tissue in a patient, comprising the steps of: (i) selecting at least a magnetic material which has a magnetic heating efficiency of at least about 4.5×10^-8 J.m./A.g, when magnetic field conditions are equal to or less than about 7.5×10⁷ A/s; (ii) delivering the magnetic material to diseased tissue in a patient; and (iii) exposing the magnetic material in the patient to a linear alternating magnetic field with a frequency of greater than about 10 kHz and a field strength such that the product of field strength, frequency and the radius of the exposed region is less than about 7.5×10⁷ A/s to generate hysteresis heat in the diseased tissue.

Claims

1. A method for site specific treatment of diseased tissue in a patient, comprising the steps of:

(i) delivering a magnetic material which has a magnetic heating efficiency of at least about 4.5×

10^-8 J.m./A.g. when magnetic field conditions are equal to or less than about 7.5×

10⁷ A/s to diseased tissue in a patient; and

(ii) exposing the magnetic material in the patient to a linear alternating magnetic field with a frequency of greater than about 10 kHz and a field strength such that the product of field strength, frequency, and the radius of the exposed region is less than about 7.5×

10⁷ A/s to generate hysteresis heat in the diseased tissue.

2. The method of claim 1, wherein steps (i) to (ii) are repeated until the diseased tissue has at least been treated sufficiently to ameliorate the disease.

3. The method of claim 1, wherein the diseased tissue contains at least a cancerous growth or contains one or more tumours.

4. The method of claim 1, wherein the magnetic material has a magnetic heating efficiency of greater than about 7×

10^-8 J.m./A.g., when magnetic field conditions are equal to or less than about 7.5×

10⁷ A/s.

5. The method of claim 1, wherein the magnetic material has a magnetic heating efficiency of greater than about 1×

10^-7 J.m./A.g., when magnetic field conditions are equal to or less than about 7.5×

10⁷ A/s.

6. The method of claim 1, wherein the magnetic material comprises a ferromagnetic material which contains at least an element selected from the group consisting of iron, manganese, arsenic, antimony, and bismith.

7. The method of claim 1, wherein the magnetic material is selected from compounds within the group of CrO₂, metallic iron, cobalt, nickel, gamma-ferric oxide, cobalt-treated gamma-ferric oxide, ferrites of the general formula MO.Fe₂ O3 where M is a bivalent metal, cobalt-treated ferrites, or magnetoplumbite-type oxides (M type) with the general formula MO.6Fe₂ O₃ where M is a large divalent ion.

8. The method of claim 7, wherein the magnetic material is a compound within the group of cobalt-treated gamma-ferric oxide compounds.

9. The method of claim 7, wherein the magnetic material is a compound within the group of un-modified gamma-ferric oxide compounds.

10. The method of claim 7, wherein the magnetic material is a compound within the group of chromium dioxide compounds.

11. The method of claim 1, wherein the magnetic material is mixed in a biocompatible liquid emulsion prior to delivery into a patient.

12. The method of claim 1, wherein the magnetic material is bound in a matrix to form microcapsules.

13. The method of claim 12, wherein the microcapsules range in size from about 10 to about 100 microns.

14. The method of claim 13, wherein the microcapsules range in size from about 20 to about 50 microns.

15. The method of claim 14, wherein the microcapsules range in size from about 30 to about 40 microns.

16. The method of claim 12, wherein the microcapsules are adapted to bind, absorb, or contain a cytotoxic material which is released upon heating of the microcapsule.

17. The method of claim 12, wherein an ionizing radiation is applied to the diseased tissue in conjunction with the magnetic field.

18. The method of claim 17, wherein the radiation is applied by microcapsules which contain a radioactive compound.

19. The method of claim 1, wherein said exposing produces a rate of tissue heating greater than 60 mW/cm³.

20. The method of claim 19, wherein the rate of tissue heating is greater than 80 mW/cm³.

21. The method of claim 19, wherein the rate of tissue heating is greater than 100 mW/cm³.

22. The method of claim 1, wherein the linear alternating magnetic field has an operational frequency of from about 10 kHz to 100 MHz.

23. The method of claim 1, wherein the linear alternating magnetic field has an operational frequency of from about 10 kHz to 500 kHz.

24. The method of claim 1, wherein the linear alternating magnetic field has an operational frequency of from about 10 kHz to 100 kHz.

25. The method of claim 1, wherein the magnetic field has an operational frequency of 20 kHz.

26. The method of claim 12, wherein the microspheres are of a suitable size to pass through a patient'"'"'s vasculature network and become dispersed and embolized within diseased tissue.

27. The method of claim 12, wherein the microcapsules range in density from 1 to 5 g/cm³.

28. The method of claim 12, wherein the microcapsules range in density from 1.8 to 3 g/cm³.

29. The method of claim 12, wherein the microcapsules range in density from 1.8 to 2.2 g/cm³.

30. The method of claim 12, wherein the microcapsules have a density of about 2 g/cm³.

31. The method of claim 1, wherein the magnetic material is bound together using a copolymer of (R)-3-hydroxybutyric acid and (R)-3-hydroxyvaleric acid.

32. The method of claim 1, wherein the magnetic material is bound together using a copolymer of (R-3-hydroxybutyric acid and (R)-3-hydroxyvaleric acid, having a density range of 1.8-2.2 g/cm³ and a range in size from 20-50 microns.

33. The method of claim 3, wherein the magnetic material is delivered to the diseased tissue by any one of the administration methods selected from the group consisting of intratumoral, peritumoral, or intravascular administrations.

34. The method of claim 1, wherein the magnetic material is delivered to the diseased tissue by arterial or venous blood supply.

35. The method of claim 1, wherein the magnetic material is delivered to the diseased tissue in combination with at least a vasoactive agent.

36. A method for generating hysteresis heat in a tissue, comprising:

delivering to the tissue magnetic material having a magnetic heating efficiency of at least about 4.5×

10^-8 J.m./A.g., when the magnetic field conditions are about 7.5×

10⁷ A/s or less; and

exposing the tissue, containing the delivered magnetic material, to a linear alternating magnetic field with a frequency of about 10 kHz or greater and a field strength such that the product of field strength, frequency, and the radius of the exposed tissue is less than about 7.5×

10⁷ A/s to generate hysteresis heat in the tissue.

37. The method of claim 36, wherein the tissue contains at least a cancerous growth or contains one or more tumor.

38. The method of claim 37, wherein said delivery and exposure are repeated until said cancerous growth or tumor is reduced in size.

39. A method for the treatment of cancerous growth or tumors, comprising:

delivering to a tissue containing a cancerous growth or tumor, a magnetic material having a magnetic heating efficiency of at least about 4.5×

10^-8 J.m./A.g., when the magnetic field conditions are about 7.5×

10⁷ A/s or less; and

exposing the tissue, containing the delivered magnetic material, to a linear alternating magnetic field with a frequency of about 10 kHz or greater and a field strength such that the product of field strength, frequency, and the radius of the exposed tissue is less than about 7.5×

10e7 A/s to generate hysteresis heat in the tissue.

40. A method for the heat treatment of a target tissue in a patient, comprising the steps of:

administering to the patient'"'"'s tissue magnetic material having a magnetic heating efficiency of at least about 4.5×

10^-8 J.m./A.g., when the magnetic field conditions are about 7.5×

10⁷ A/s or less; and

selectively exposing the tissue to a linear alternating magnetic field with a frequency of about 10 kHz or greater and a field strength such that the product of field strength, frequency, and the radius of the exposed tissue is less than about 7.5×

10e7 A/s to generate hysteresis heat in the tissue.

41. The method of claim 40, wherein said administering comprises injecting microcapsules comprising the magnetic material.

42. The method of claim 40, wherein said microcapsules further comprise a cytotoxic agent.

43. The method of claim 40, further comprising the step of:

exposing the tissue to ionizing radiation.

44. The method of claim 43, wherein said exposure is from an external radiation source.

45. The method of claim 41, wherein said microcapsules further comprise a radioactive compound.