Classifications

• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61K—PREPARATIONS FOR MEDICAL, DENTAL OR TOILETRY PURPOSES
  • A61K9/00—Medicinal preparations characterised by special physical form
  • A61K9/10—Dispersions; Emulsions
  • A61K9/127—Synthetic bilayered vehicles, e.g. liposomes or liposomes with cholesterol as the only non-phosphatidyl surfactant
  • A61K9/1271—Non-conventional liposomes, e.g. PEGylated liposomes or liposomes coated or grafted with polymers
• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61K—PREPARATIONS FOR MEDICAL, DENTAL OR TOILETRY PURPOSES
  • A61K31/00—Medicinal preparations containing organic active ingredients
  • A61K31/33—Heterocyclic compounds
  • A61K31/395—Heterocyclic compounds having nitrogen as a ring hetero atom, e.g. guanethidine or rifamycins
  • A61K31/435—Heterocyclic compounds having nitrogen as a ring hetero atom, e.g. guanethidine or rifamycins having six-membered rings with one nitrogen as the only ring hetero atom
  • A61K31/4353—Heterocyclic compounds having nitrogen as a ring hetero atom, e.g. guanethidine or rifamycins having six-membered rings with one nitrogen as the only ring hetero atom ortho- or peri-condensed with heterocyclic ring systems
  • A61K31/436—Heterocyclic compounds having nitrogen as a ring hetero atom, e.g. guanethidine or rifamycins having six-membered rings with one nitrogen as the only ring hetero atom ortho- or peri-condensed with heterocyclic ring systems the heterocyclic ring system containing a six-membered ring having oxygen as a ring hetero atom, e.g. rapamycin
• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61K—PREPARATIONS FOR MEDICAL, DENTAL OR TOILETRY PURPOSES
  • A61K9/00—Medicinal preparations characterised by special physical form
  • A61K9/10—Dispersions; Emulsions
  • A61K9/127—Synthetic bilayered vehicles, e.g. liposomes or liposomes with cholesterol as the only non-phosphatidyl surfactant
• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61K—PREPARATIONS FOR MEDICAL, DENTAL OR TOILETRY PURPOSES
  • A61K9/00—Medicinal preparations characterised by special physical form
  • A61K9/10—Dispersions; Emulsions
  • A61K9/127—Synthetic bilayered vehicles, e.g. liposomes or liposomes with cholesterol as the only non-phosphatidyl surfactant
  • A61K9/1277—Preparation processes; Proliposomes
  • A61K9/1278—Post-loading, e.g. by ion or pH gradient
• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61P—SPECIFIC THERAPEUTIC ACTIVITY OF CHEMICAL COMPOUNDS OR MEDICINAL PREPARATIONS
  • A61P35/00—Antineoplastic agents
• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61P—SPECIFIC THERAPEUTIC ACTIVITY OF CHEMICAL COMPOUNDS OR MEDICINAL PREPARATIONS
  • A61P35/00—Antineoplastic agents
  • A61P35/02—Antineoplastic agents specific for leukemia

Definitions

• the application relates to the field of anti-cancer drugs, in particular, methods for loading hydrophobic anti-cancer drugs into liposomes and for treatment of cancers with the liposomes.
• Rapamycin also known as sirolimus, is a macrolide antibiotic initially developed for use as an immune suppressor for transplant patients. Subsequently, it was used as a drug coating for coronary artery stents, where it functions to reduce restenosis following angioplasty by inhibiting smooth muscle cell proliferation.
• Sirolimus and derivatives of this drug have also been found to be effective for treating certain cancers.
• sirolimus has anti-tumor activity. See US Patent 4,885,171.
• Everolimus, the 40-O-(2-hydroxyethyl) derivative of sirolimus has been approved for treating advanced kidney cancer, advanced hormone receptor- positive/HER2-negative breast cancer, and pancreatic neuroendocrine tumors.
• umirolimus i.e., 40-alkoxyalkyl-rapamycin
• umirolimus-loaded polymer micelles can both inhibit cancer cell growth in vitro and the micelles are effective for slowing the growth of experimental tumors in vivo. See US Patent Application Publication 2014/0154305.
• umirolimus significantly improves the solubility and stability of this drug and results in its sustained delivery.
• liposomes have been employed to improve drug delivery of sirolimus and its derivatives.
• sirolimus, everolimus, and tacrolimus have been encapsulated in liposomes using two passive loading methods, namely, thin-film hydration and ethanol injection.
• the amount of drug encapsulated and drug encapsulation efficiency is particularly low, i.e., ⁇ 0.5 mg/mL and ⁇ 90%, respectively.
• Drug leakage from the liposomes also occurs with passive loading techniques.
• a remote film loading technique that requires steps of drug dissolution and solvent removal has been used to entrap sirolimus into pre-formed liposomes.
• Such methods should form drug-loaded liposomes having a higher therapeutic index as compared to existing liposomes, particularly for umirolimus and other rapamycin-derivatives.
• the stable formulation includes a liposome that contains at least one lipid bilayer formed of one or more phosphatidylcholine selected from
• the liposome has a diameter of 50 nm to 2 ⁇ and is free of cholesterol. Encapsulated in the liposome is an anticancer drug selected from sirolimus, umirolimus, and everolimus.
• a method for loading a hydrophobic drug into liposomes includes the steps of (i) obtaining cholesterol-free liposomes having at least one lipid bilayer, (ii) adding the cholesterol-free liposomes to an aqueous solution to form a suspension such that there is substantially no transmembrane potential across the lipid bilayer, (iii) adding a hydrophobic drug in the absence of a solubility enhancer to the suspension to form a mixture, and (iv) stirring the mixture for 4 to 48 hours at room temperature.
• the method results in loading of at least 80% of the hydrophobic drug into the liposomes.
• the method consists of the steps set forth in this paragraph.
• a method for preparing a hydrophobic drug encapsulated in a cholesterol-free liposome is disclosed. The method is carried out by (i) suspending one or more of POPC, DMPC, and DOPC in an aqueous buffer to form a lipid suspension, (ii) stirring the lipid suspension for at least 30 minutes at room temperature to form multilamellar vesicles (MLVs), (iii) extruding the MLVs to form large unilamellar vesicles (LUVs) having a diameter of 50 nm to 2 ⁇ , (iv) adding the LUVs to an aqueous solution to form a suspension such that there is substantially no transmembrane potential across the LUVs, (v) adding a hydrophobic drug to the suspension in the absence of a solubility enhancer to form a mixture, (vi) stirring the mixture for 4 to 48 hours at room temperature to form a drug-loaded liposome suspension, and (vii) filtering the drug-loaded lip
• a method for treating cancer is also disclosed.
• the method requires the steps of administering to a subject in need thereof an effective amount of the stable liposomal formulations described above.
• the effective amount is sufficient to inhibit growth of cancer cells in the subject.
• Fig. 1 is a plot of the in vitro drug release profile of umirolimus (URL) and liposomal umirolimus (LipoURL);
• Fig. 2 is a plot of the in vitro drug release profile of everolimus (ERL) and liposomal everolimus (LipoERL); and
• Fig. 3 is a plot of the in vitro drug release profile of sirolimus (SRL), and liposomal sirolimus (LipoSRL).
• a stable liposomal formulation for treating cancer contains at least one lipid bilayer formed of a phosphatidylcholine selected from POPC, DMPC, and DOPC, or mixtures of these three phosphatidylcholines, and are free of cholesterol.
• the liposomes contain one lipid bilayer.
• the liposomes contain only POPC, DMPC, or DOPC.
• the liposomes contain only POPC.
• the lipid bilayer of the liposomes includes the
• the PEG-conjugated phospholipid can be l,2-distearoyl-sn-glycero-3- phosphoethanolamine-N-[amino(PEG)](DSPE-PEG); l,2-dioleoyl-sn-glycero-3- phosphoethanolamine-N-[methoxy(PEG)] (DOPE- PEG); 1 ,2-dipalmitoyl-sn-glycero- 3 -phosphoethanolamine-N- [methoxy(PEG)] (DPPE-PEG) ; 1 ,2-dimyristoyl-sn- glycero-3-phosphoethanolamine-N-[methoxy(PEG)](DMPE-PEG); or mixtures thereof.
• the PEG-conjugated phospholipid is DSPE-PEG.
• the weight ratio between them can be 5:1 to 100:1, e.g., 5:1, 7.5:1, 10:1, 15:1, 20:1, 30:1, 40:1, 50:1, 60:1, 70:1, 80: 1, 90:1, and 100:1.
• a preferred ratio is 10:1.
• phospholipid can be 150 to 3000 g/mol, e.g., 150, 200, 250, 300, 350, 500, 750, 1000, 1250 1500, 1750, 2000, 2250, 2500, 2750, 3000 g/mol.
• the molecular weight of the PEG moiety is 2000 g/mol.
• the liposomes can have a diameter of 50 nm to 2 ⁇ (e.g., 50 nm, 100 nm, 150 nm, 200 nm, 250 nm, 500 nm, 1 ⁇ , 1.5 ⁇ , and 2 ⁇ ). In an embodiment, the liposomes have a diameter of 50 nm to 500 nm. In a preferred embodiment, the diameter is 100 nm.
• the liposomes in the stable liposomal formulation encapsulate a hydrophobic drug for treating cancer.
• the hydrophobic drug can be an anti -proliferative drug, e.g., sirolimus, umirolimus, or everolimus.
• the hydrophobic drug is umirolimus.
• the weight ratio between the hydrophobic drug and the phosphatidylcholine component of the liposomes can be 1 :5 to 1 :100 (e.g., 1 :5, 1:10, 1: 15, 1 :20, 1 :25, 1:30, 1 :35, 1:40, 1 :45, 1 :50, 1:75, and 1 :100).
• the drug to phosphatidylcholine weight ratio is 1:10.
• the weight ratio is 1:20.
• the concentration of the hydrophobic drug in the stable liposomal formulation can be 0.01 mg/mL to 10 mg/mL.
• the drug concentration in the formulation can be 0.01 mg/mL, 0.05 mg/mL, 0.5 mg/mL, 1.0 mg/mL, 2.5 mg/mL, 5.0 mg/mL, and 10 mg/mL.
• the drug concentration is 1 mg/mL.
• the stable liposomal formulation can have a pH of 6.0 to 8.0. In a preferred embodiment, the pH is 7.4.
• the stable liposomal formulation for treating cancer includes liposomes formed only of POPC and DSPE-PEG 2000, the liposomes having umirolimus encapsulated therein.
• the liposomes are cholesterol-free, have a diameter of about 100 nm, and the weight ratio between the umirolimus and the POPC is 1:20.
• This specific formulation contains 1 mg/mL of umirolimus and has a pH of 7.4.
• the stable liposomal formulation also improves the stability of the
• hydrophobic drug in solution can be stable for 7-14 days when stored at 5 °C as compared to the drug in an aqueous suspension.
• stability is defined as a loss of no more than 5 % of the starting amount of drug in the formulation.
• the hydrophobic drug can be released from the liposomes in the formulation over an extended period of time after administration. That is to say, the formulation is a sustained release formulation.
• the hydrophobic drug can be released from the liposomes after administration of the formulation continuously over a period of up to 3 months, e.g., 7, 14, 21 days and 1, 2, and 3 months.
• a method for loading a hydrophobic drug into liposomes is provided.
• the method is an improved remote film loading technique in which the liposomes are obtained first and the hydrophobic drug is then loaded into the liposomes.
• the liposomes for use in the loading method are cholesterol-free, have at least one lipid bilayer that contains one or more of POPC, DMPC, and DOPC, and have a diameter of 50 nm to 2 ⁇ . In an embodiment, the liposomes contain only POPC.
• the cholesterol-free liposomes have at least one lipid bilayer that contains one or more of POPC, DMPC, and DOPC and also contains a PEG- conjugated phospholipid selected from DSPE-PEG, DOPE-PEG, DPPE-PEG, and DMPE-PEG.
• phospholipid can be 150 to 3000 g/mol, e.g., 150, 200, 250, 300, 350, 500, 750, 1000, 1250 1500, 1750, 2000, 2250, 2500, 2750, 3000 g/mol.
• the molecular weight of the PEG moiety is 2000 g/mol.
• the liposomes contain only POPC. In another embodiment, the liposomes contain only POPC and DSPE-PEG2000.
• the liposomes can be obtained by forming MLVs that contain one or more of POPC, DMPC, DOPC, and, optionally, DSPE-PEG2000, and extruding the MLVs to obtain cholesterol-free liposomes having a diameter of 50 nm to 2 ⁇ . More specifically, one or more of POPC, DMPC, DOPC, and, optionally, DSPE-PEG2000 are suspended in an aqueous buffer to form a lipid suspension, the suspension is stirred for at least 30 minutes at room temperature to form MLVs.
• the MLVs are converted into large unilamellar vesicles (LUVs) by an extrusion process.
• the MLVs can be extruded through a 3-layered polycarbonate filter from 3 to 20 times.
• the MLVs are extruded 10 times.
• the polycarbonate filter can have a pore size ranging from 50 nm to 200 nm. In a particular embodiment, the pore size is 100 nm.
• the resulting LUVs i.e., liposomes, can have a diameter of 50 nm to 2 ⁇ .
• the cholesterol-free liposomes described above are then added to an aqueous solution to form a suspension.
• the aqueous solution employed should be the same solution or similar to that used for producing the cholesterol-free liposomes such that there is substantially no transmembrane potential across the lipid bilayer of the liposomes.
• the ionic strength, pH, and osmolality should be closely matched such that there is no ionic gradient, pH gradient, or osmotic gradient across the liposomal membrane. This can be ensured, e.g., by using PBS to form the cholesterol-free liposomes and also diluting them in PBS to form the suspension.
• the phrase "substantially no transmembrane potential” means a level of transmembrane potential below which a drug would not be actively loaded into the liposome.
• a hydrophobic drug is added to the suspension of liposomes in the aqueous solution to form a mixture.
• the hydrophobic drug can be sirolimus, umirolimus, or everolimus. In a particular method, the drug is umirolimus.
• the loading method at this stage does not require the use of a solubility enhancer, e.g. a cyclodextrin, to solubilize the hydrophobic drug in the aqueous solution. Indeed, this is not necessary or desirable.
• the hydrophobic drug as it is added to the liposomes suspended in the aqueous solution, interact strongly with lipid tails of the liposomes due to the hydrophobic nature of the drug, leading to its encapsulation inside the lipid bilayer of the liposome.
• the mixture of liposomes and hydrophobic drug is stirred for 4 to 48 hours at room temperature, resulting in at least 80% (e.g., 80%, 85%, 90%, 95%, and 100%) of the added hydrophobic drug loaded into the cholesterol-free liposomes.
• an effective amount of the stable liposomal formulation that contains an anti-cancer drug selected from sirolimus, umirolimus, or everolimus is administered to a cancer patient.
• the effective amount inhibits growth of cancer cells in the patient.
• a skilled person in the art can readily determine the effective amount of the stable liposomal formulation that should be administered to the cancer patient. For example, response to drug dose over time can be followed by measuring tumor size by MRI or CT scan.
• the stable liposomal formulations can be administered to a cancer patient via any conventional method, including, but not limited to, intraperitoneal injection, intravenous injection, direct injection into a tumor, injection into the arterial circulation upstream of a tumor, and nasal inhalation.
• the stable liposomal formulations described above can also be formed into a pill or a capsule for oral administration.
• the types of cancer that can be treated by administering the above-described stable liposomal formulations include but are not limited to acute lymphocytic leukemia, acute myeloid leukemia, adrenal cancer, adult soft tissue sarcoma, anal cancer, aplastic anemia, basal and squamous cell skin cancer, bile duct cancer, bladder cancer, bone cancer, brain/CNS tumors, breast cancer, breast cancer in man, cancer in children, cancer of unknown primary, Castleman's disease, cervical cancer, chronic lymphocytic leukemia, chronic myeloid leukemia, chronic myelomonocytic leukemia, colorectal cancer, endometrial cancer, esophagus cancer, Ewing Family of tumors, eye cancer, gallbladder cancer, gastric cancer, gastrointestinal carcinoid,
• gastrointestinal stromal tumor gestational trophoblastic disease, Hodgkin' s disease, Kaposi's sarcoma, kidney cancer, laryngeal and hypopharyngeal cancer, leukemia in children, liver cancer, lung cancer-non small cell, lung cancer-small cell, Lung carcinoid tumor, malignant mesothelioma, melanoma skin cancer, multiple myeloma, myelodysplastic syndrome, nasal cavity and paranasal sinus cancer, nasopharyngeal cancer, neuroblastoma, non-Hodgkin's lymphoma, oral cavity and oropharangeal cancer, osteosarcoma, ovarian cancer, pancreatic cancer, penile cancer, pituitary tumors, prostate cancer, renal cell carcinoma, retinoblastoma, rhabdomyosarcoma, salivary gland cancer, skin lymphoma, small intestine cancer, stomach cancer, testicular cancer, thymus cancer,
• phosphatidylcholine namely, EggPC, POPC, DMPC, or DOPC.
• PBS phosphate buffered saline
• the mixtures were stirred at room temperature for at least 30 min. to form multilamellar vesicles (MLVs).
• MLVs multilamellar vesicles
• the sizes of the MLVs were reduced by extrusion through a 3-stack of polycarbonate filter membranes (pore size 100 nm) using a bench top extruder (Northern Lipids Inc., Canada). After 10 extrusion passes, large unilamellar vesicles (LUVs) with an average size of -100 nm were obtained.
• LUVs large unilamellar vesicles
• the umirolimus content of the liposomal solutions after loading was determined by reverse-phase HPLC.
• the liposomes were broken by mixing 50 ⁇ samples of each liposomal solution with 1.0 ml of acetonitrile.
• a standard solution of umirolimus was prepared at 0.05 mg/mL in methanol. Samples were analyzed by HPLC and compared to the standard solution to quantify the amount of umirolimus in the liposome.
• the amount of umirolimus loaded into liposomes formed of DMPC, POPC, and DOPC was greater than 2.7 mg/mL. Unexpectedly, the amount of umirolimus loaded into these three liposomes was higher than that loaded into liposomes formed of EggPC.
• Liposomes containing a polyethylene glycol-conjugated (PEGylated) phospholipid were prepared by combining 1800 mg of POPC and 200 mg of DSPE PEG-2000 in 200 mL of PBS in a 500 mL depyrogenated glass bottle. The mixture was stirred at room temperature for at least 30 min. to form MLVs. The sizes of the MLVs were reduced by extrusion through a 3 -stack of polycarbonate filter membranes (pore size 100 nm) using a bench top extruder (Northern Lipids Inc., Canada). After 10 extrusion passes, PEGylated LUVs with an average size of approximately 100 nm were obtained.
• PEGylated LUVs with an average size of approximately 100 nm were obtained.
• the stability of the umirolimus-loaded PEGylated liposome formulation was evaluated during storage in clear glass vials at 5°C + 3°C. The sample temperature was monitored and recorded continuously to ensure constant temperature conditions. The solution was analyzed for umirolimus content, vesicle size, and PDI as described above in EXAMPLE 1 after storage for 2, 3, 4, 6, and 8 weeks. The stability results are shown in TABLE 2 below.
• PEGylated liposomes were prepared as described above in EXAMPLE 1 and EXAMPLE 2, respectively.
• the drug encapsulation efficiencies are shown in TABLE 3 below.
• the encapsulation efficiency of both the umirolimus-loaded POPC liposomes and the umirolimus-loaded POPC PEGylated liposomes was greater than 95%.
• POPC LUVs were prepared as described above in EXAMPLE 1. 50 mg of sirolimus or everolimus were added to a 50 mL depyrogenated glass bottle together with 10 mL of the POPC LUVs. The glass bottle was capped and placed in a water bath at a temperature of 25 °C. The mixture was stirred at room temperature for 24 h. The drug-loaded liposome solution was filtered through a 0.2 ⁇ PVDF syringe filter to removed un-encapsulated drug.
• a control formulation was prepared containing 1.0 mg of drug in 5 mL of a solution containing 15% acetonitrile and 85% water. 5 mL of the control formulations and the liposomal formulations for each drug were loaded into separate dialysis tubes having a molecular weight cut-off of 50 kDal.
• Each loaded dialysis tube was placed in an individual 50 mL tube containing 40 mL of release media (15% acetonitrile and 0.5 % SDS).
• the release media in each tube was sampled after 1, 2, 5, 7, 24, 30, and 48 h and the drug concentration in the release media was determined by HPLC as described above in EXAMPLE 1.
• the cumulative drug release percentage versus release time was plotted for all samples. The results are shown in Figures 1, 2, and 3 for umirolimus, everolimus, and sirolimus, respectively.

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• 2015
  • 2015-09-09 US US14/849,100 patent/US20170065520A1/en not_active Abandoned
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