Liposomal formulations comprising dihydrosphingomyelin and methods of use thereof

• US 20060008909A1
• Filed: 05/16/2005
• Published: 01/12/2006
• Est. Priority Date: 05/17/2004
• Status: Active Grant

• Current Assignee: Tekmira Pharmaceuticals Corporation
• Original Assignee: Inex Pharmaceuticals Corporation
• Inventors: Ansell, Steven M., Semple, Sean C., Cullis, Pieter R., Maurer, Norbert, Madden, Thomas D., Hope, Michael J., Mui, Barbara L. S.
• Granted Patent: US 7,811,602 B2
• Time in Patent Office: Days
• US Class Current: 435/458
• CPC Class Codes: A61K 2300/00 Mixtures or combinations of active ingredients, wherein at least one active ingredient is fully defined in groups A61K31/00 - A61K41/00
• CPC Class Codes: A61K 31/4745 condensed with ring systems having nitrogen as a ring hetero atom, e.g. phenantrolines yohimbine derivatives, vinblastine A61K31/475; ergoline derivatives A61K31/48
• CPC Class Codes: A61K 33/32 Manganese; Compounds thereof
• CPC Class Codes: A61K 9/1272 with substantial amounts of non-phosphatidyl, i.e. non-acylglycerophosphate, surfactants as bilayer-forming substances, e.g. cationic lipids with cholesterol as the only non-phosphatidyl surfactant A61K9/127; lipids as modifying agent A61K47/543
• CPC Class Codes: A61K 9/1278 Post-loading, e.g. by ion or pH gradient

Abstract

The present invention includes novel liposomes comprising dihydrosphingomyelin. The invention also includes compositions comprising these liposomes and a therapeutic agent, in addition to methods and kits for delivering a therapeutic agent or treating a disease, e.g., a cancer, using these compositions.

Claims

1. A liposome comprising dihydrosphingomyelin (DHSM), wherein said DHSM constitutes at least 50% (molar basis) of total phospholipid present in said liposome.

3. The liposome of claim 1, wherein the N-acyl chain of said DHSM consists of 12 to 24 carbon atoms.

4. The liposome of claim 1, wherein the DHSM is selected from the group consisting of:

N-palmitylsphinganyl-1-O-phosphorylcholine;

N-stearylsphinganyl-1-O-phosphorylcholine;

N-myristylsphinganyl-1-O-phosphorylcholine; and

N-arachidylsphinganyl-1-O-phosphorylcholine.

5. The liposome of claim 1, wherein the DHSM N-acyl and dihydrosphingosine chains comprise carbon chains that are not different in length by more than four carbon atoms.

6. The liposome of claim 1, further comprising cholesterol at a molar ratio from 75/25 (mol/mol) total phospholipid/cholesterol to 25/75 (mol/mol) total phospholipid/cholesterol.

7. The liposome of claim 1, wherein the interior of said liposome comprises MnSO₄.

8. A liposomal composition comprising liposomes of claim 1, wherein said liposomes comprise a therapeutic compound.

9. The liposomal composition of claim 8, wherein the therapeutic compound is an antineoplastic agent.

10. The liposomal composition of claim 9, wherein the antineoplastic agent is selected from the group consisting of:

vinca alkaloids, camptothecins, NK611, etoposide, and taxanes.

11. The liposome composition of claim 8, further comprising empty liposomes.

2. A liposome comprising dihydrosphingomyelin (DHSM), wherein said DHSM constitutes at least 20% (molar basis) of total phospholipid present in said liposome.

12. A method of delivering a therapeutic agent to a patient, comprising administering to the patient a pharmaceutical composition comprising a liposome-encapsulated therapeutic agent, wherein said liposome comprises dihydrosphingomyelin (DHSM), and wherein said DHSM constitutes at least 50% (molar basis) of total phospholipid present in said liposome.

13. The method of claim 12, wherein the liposome further comprises cholesterol at a molar ratio from 75/25 (mol/mol) total phospholipid/cholesterol to 25/75 (mol/mol) total phospholipid/cholesterol.

14. The method of claim 13, wherein the therapeutic compound is an antineoplastic agent.

15. The method of claim 14, wherein the antineoplastic agent is selected from the group consisting of:

vinca alkaloids, camptothecins, NK611, etoposide, and taxanes.

16. A method of treating a cancer in a mammal, comprising administering to the mammal a pharmaceutical composition comprising a liposome-encapsulated therapeutic agent, wherein said liposome comprises dihydrosphingomyelin (DHSM), and wherein said DHSM constitutes at least 50% of total phospholipids present in said liposome.

17. The method of claim 16, wherein the liposome further comprises cholesterol at a molar ratio from 75/25 (mol/mol) total phospholipid:

cholesterol to 25/75 (mol/mol) total phospholipid;

cholesterol.

18. The method of claim 16, wherein the cancer is a leukemia or lymphoma.

19. The method of claim 16, wherein the cancer is a solid tumor.

20. A method of producing a pharmaceutical composition, comprising loading a liposome comprising dihydrosphingomyelin (DHSM) with a therapeutic compound, wherein said DHSM comprises at least 50% of the total phospholipids present in said liposome.

21. The method of claim 20, wherein said liposome comprises a buffer containing MnSO₄ at a concentration equal to or greater than 300 mM, wherein said loading is performed at a temperature equal to or greater than 60°

C. and in the presence of an ionophore.

22. A method of loading a therapeutic agent into a liposome comprising:

incubating a liposome comprising dihydrosphingomyelin (DHSM) and having an encapsulated medium comprising MnSO₄, wherein said DHSM comprises at least 50% of the total phospholipid of the liposome, with an external solution comprising said therapeutic agent and an ionophore at a temperature greater than 60°

C. to form a therapeutic agent-loaded liposome.

23. A kit comprising:

(a) a liposome comprising dihydrosphingomyelin (DHSM), wherein said DHSM constitutes at least 50% of total phospholipid present in said liposome, and

(b) a therapeutic compound.