SMALL PARTICLE LIPOSOME AEROSOLS FOR DELIVERY OF ANTI-CANCER DRUGS

Abstract: The small particle liposome aerosol compounds and methods of treatment of the present invention involve lipid- or water soluble anti-cancer drugs incorporated into liposomes. The liposomes are administered in aqueous dispersions from a jet nebulizer to the respiratory tract of an individual. Various anti-cancer drugs may be used, including 20-S-Camptothecin, 9-Nitro-camptothecin, 9-Amino-camptothecin, 10, 11-methylenedioxy-camptothecin and taxol or its derivatives. Administration of these drugs by inhalation provides faster and more efficient absorption of the anti-cancer drug than does intramuscular administration or oral administration.

Description: SMALL PARTICLE LIPOSOME AEROSOLS FOR DELIVERY OF ANTI-CANCER DRUGS BACKGROUND OF THE INVENTION Field of the Invention The present invention relates generally to the field of pharmacology and cancer treatment. Specifically, the pre s ent invention provides formulations and methods for small particle aerosol delivery by inhalation of aqueous dispersions of liposomes carrying anti-cancer drugs to the respiratory tract. Description of the Related Art Small particle liposome aerosol treatment consists of lipid-soluble or water-soluble anti-cancer drugs incorporated into liposomes, which are administered from aqueous dispersions in a jet nebulizer (see U.S. Patent No. 5,049,388). Aerosols of 1 - 3 μm mass median aerodynamic diameter, generated upon nebulization, enable targeted delivery onto surfaces of th e respiratory tract. The deposited liposomes subsequently release drug locally within the lung or into the blood circulation with delivery to extra-pulmonary tissue. If the drug is lipid soluble, it will associate with the lipid molecules in a manner specific to the lipid employed, the anti-cancer drug employed and possibly it may be modified further by various soluble constituents which may be included in the suspending aqueous medium. Such soluble constituents may include buffering salts and possibly inositol to enhance the synthesis and secretion of surfactant phospholipid in lung tissue and to minimize respiratory distress already present or that which might result from the aerosol treatment (Hallman, M., et al. Inositol Supplementation in Premature Infants with Respiratory Distress Syndrome, N. Eng. J. Med. 1992 326: 1233- 1239). If the drug is water soluble, it may be incorporated b y appropriate procedures in aqueous vesicles that exist in concentric spaces between lipid bilayers (lamellae) of th e multilamellar liposome. Unilamellar liposomes may b e prepared; however, their capacity to entrap either lipid-soluble or water-soluble drugs is diminished since entrapment is restricted to one central vesicle. Aerosol water droplets may contain one or more drug- liposomes. Nebulization shears liposomes to sizes readily discharged from the nozzle of the nebulizer. Liposomes up to several microns in diameter are typically sheared to diameters of less than 500 nm, and may be considerably smaller than that depending on the operating characteristics of the nebulizer and other variables. Shearing of water-soluble drugs contained in liposomes will release appreciable amounts of the water soluble compound, perhaps 50 percent. This is not a contraindication to their use, but it means that two forms of the drug preparation is administered, and the effect includes the therapeutic effect th at would be produced by both forms if either form had been given alone. Many other details of liposome aerosol treatment are described in U.S. Patent No. 5,049,388. Moreover, it is also possible to incorporate more than one drug in a aerosol liposome treatment, either by mixing different drug-containing liposomes, or by using liposomes wherein the drugs have b een combined and incorporated together into liposomes. The prior art is deficient in formulations and methods for small particle aerosol delivery of aqueous dispersions of liposomes containing anti-cancer drugs. The present invention fulfills this long-standing need and desire in the art. SUMMARY OF THE INVENTION The small particle liposome aerosol compounds and methods of treatment of the present invention involve lipid- soluble or water-soluble anti-cancer drugs incorporated into liposomes. The liposomes then are administered in aqueous dispersions from a jet nebulizer. The present invention demonstrates that speedier and more efficient systemic absorption of drug is actualized after pulmonary administration by aerosol than is actualized by intramuscular or oral administration. One object of the present invention is to provide a method for treating cancer, comprising the step of delivering, via small particle aerosol, aqueous dispersions of anti-cancer drugs to the respiratory tract of an individual in need of such treatment. Examples of anticancer drugs available for use in this embodiment of the invention include, but are not limited to, 20-S - camptothecin, 9-nitro-camptothecin, 9-amino-camptothecin, 10, 1 1 -methylenedioxy-camptothecin, taxol, taxol-A, mitotane, methotrexate, mercaptopurine, lomustine, interferon, 5 - fluorouracil and etopiside. In a more preferred embodiment of this object, the anti-cancer drug is selected from the group consisting of 20-S-camptothecin, 9-nitro-camptothecin, 9-amino- camptothecin, 10, 1 1-methylenedioxy-camptothecin and taxol. Additionally, in a preferred embodiment of the present objective, the delivery of the anticancer drug is performed by a j et nebulizer. In another object of the present invention, there is provided a liposome for delivery of anticancer drugs via small particle aerosols comprising an anticancer drug and a lipid, wherein the anticancer drug is at a concentration not exceeding about 10% of the total volume of the preparation and a ratio of th e anticancer drug to the suitable solvent is in the range of about 1 : 1 to about 1 :200, preferably in a range of about 1 : 10 to about 1 : 100, and most preferably in a range of about 1 : 10 to about 1 :50 (wt:wt) of the preparation. One specific embodiment of this object includes 9-nitro-camptothecin and dilauroylphosphatidylcholine in a ratio of about 1 : 10 to 1 :50 wt:wt; with a particularly preferred embodiment having a 9-nitro-camptothecin and dilauroylphosphatidylcholine of about 1 :50 wt:wt. In another embodiment, there is provided a liposome for delivery of anticancer drugs via small particle aerosols comprising Taxol and dilauroylphosphatidylcholine in a ratio of about 1 :30 wt:wt. In yet another embodiment of the present invention, there is provided a liposome produced by the following steps : dissolving a lipid-soluble anticancer drug in a solvent suitable for dissolving the anticancer drug to produce dissolved anticancer drug; adding the dissolved anticancer drug to a dissolved lipid suitable for formulation and delivery of drugs by aerosol to produce a solution, wherein the dissolved anticancer drug is at a concentration not exceeding about 10% of the total volume of th e solution and a ratio of the anticancer drug to the lipid is in the range of about 1 : 1 to about 1 :200, preferably in a range of about 1 : 10 to about 1 : 100, and most preferably in a range of about 1 : 10 to about 1 :50 (wt:wt) of the solution; and freezing and lyophilizing the solution. At this point, the solution may be stored frozen for later use or dissolved in sterile water for use, producing a suspension, wherein the concentration of the anticancer drug in the sterile water in the suspension is no more than about 5.0 mg/ml . A preferred embodiment of the above object provides liposomal preparations of 20-S-camptothecin (CPT), 9 - nitrocamptothecin (9-NC) and other lipid soluble camptothecin derivatives, produced by the following steps: preparing concentrated stock solutions of said 20-S-camptothecin (CPT), 9 - nitrocamptothecin (9-NC) or other-lipid soluble camptothecin derivatives and lipids in compatible solvents; adding appropriate volumes of the 20-S-camptothecin (CPT), 9-nitrocamptothecin ( 9 - NC) or other-lipid soluble camptothecin derivative and lipid concentrated stock solutions to a volume of t-butanol to form a second solution, wherein a concentration of said 20- S - camptothecin (CPT), 9-nitrocamptothecin (9-NC) and other lipid soluble camptothecin derivatives does not exceed 10% of said second solution and wherein a ratio of drug to lipid is in the range of about 1 : 1 to about 1 :200, preferably in a range of about 1 : 10 to about 1 : 100, and most preferably in a range of about 1 : 10 to about 1 :50 (wt:wt) in said second solution; freezing said second solution; and lyophilizing said second solution to produce a powder preparation. At this point, the powder preparation may be stored frozen for later use or dissolved in sterile water producing a suspension, wherein a concentration of said anticancer drug in said suspension is no more than about 5 mg/ml. A more particular embodiment provides liposomes produced by the following steps: preparing a concentrated stock solutions of anticancer drug, for example 100 mg CPT in 1 ml t - butanol or 100 mg 9-NC in DMSO, preparing a stock solution of lipid, for example, 100 mg DLPC in 1 ml butanol; adding appropriate volumes of said concentrated stock solutions to a volume of t-butanol to form a second solution wherein a final volume is about 10 ml, a volume of DMSO, if any, does not exceed 10% (vol:vol) of said final volume, a concentration of anticancer drug does not exceed 10% (wt:wt) of the total volume, and wherein a ratio of drug to lipid is in a range of about 1 : 1 to about 1 :200, preferably in a range of about 1:10 to about 1 : 100, and most preferably in a range of about 1 : 10 to about 1 :50 (wt:wt); freezing said second solution; and lyophilizing said frozen solution to produce a powder preparation. Tthe powder preparation m a y then be stored frozen for later use or dissolved in sterile w ater producing a suspension. Generally, the concentration of th e anticancer drug in the suspension is no more than about 5 mg/ml. Another preferred embodiment of the object above provides a liposome produced by the following steps: mixing taxol with synthetic alpha lecithin: dilauroylphosphatidylcholine; dissolving the taxol-DLPC in t-butanol to produce a preparation; and freezing and lyophilizing the preparation. Liposomes are produced by adding sterile, pure water at a temperature above 25°C, wherein the final concentration of taxol to dilauroylphosphatidylcholine is about 1 : 1 to about 1 :200, preferably in a range of about 1 : 10 to about 1 : 100, and most preferably in a range of about 1 :25 to about 1 :40 (wt:wt). I n addition to alpha lecithin, other natural or synthetic lecithins m a y be used, including but not limited to egg yolk phosphatidylcholine, hydrogenated soybean phosphatidylcholine, dimyristophosphatidylcholine, diolyeolyl- dipalmitoyleolylphospha-tidylcholine and dipalmitoyl phosphatidylcholine. The efficiency of incorporation of 9-NC and other camptothecin derivatives and anticancer drugs into liposomes can be tested by layering an aqueous dispersion of lyophilized drug - liposome preparation over a Percoll™ gradient and centrifuging. Unincorporated drug collects at the bottom of the tube, but drug incorporated into liposomes collects at the interface between th e Percoll gradient and the water phase. One qualitative test of incorporation efficiency is the observation of drug crystals w h en the dispersion of drug-liposomes are examined by microscopy under polarized light. Other methods are also available, for example, analytical HPLC methods can be used to quantitatively assess non-encapsulated, crystalized drug. Other and further aspects, features, and advantages of th e present invention will be apparent from the following description of the presently preferred embodiments of the invention. These embodiments are given for the purpose of disclosure. BRIEF DESCRIPTION OF THE DRAWINGS The appended drawings have been included herein so that the above-recited features, advantages and objects of th e invention will become clear and can be understood in detail. These drawings form a part of the specification. It is to be noted, however, that the appended drawings illustrate preferred embodiments of the invention and should not be considered to limit the scope of the invention. Figure 1 : shows the effect of treatment with 9-NC- DLPC liposome aerosol on xenografted human breast cancer in nude mice. Figure 2 : shows the effect of further treatment with 9-NC-DLPC liposome aerosol in mice selected from Figure 1. Figure 3 : shows the effect of treatment with 9-NC- DLPC liposome aerosol on xenografted human colon cancer (Squires) in nude mice. Figure 4: shows the effect of treatment with 9-NC- DLPC by liposome aerosol or by oral administration on the growth of human lung cancer xenografts (Spark) in nude mice a s measured by tumor volume. Figure 5: shows the output of Taxol-DLPC liposomes (1 :30; lmg/ml) with the Aerotech II nebulizer. Figure 6: shows the recovery of taxol from the preparation described in Figure 5; taxol-DLPC dosage at 15 bpm, 500 ml TV. DETAILED DESCRIPTION OF THE INVENTION The following definitions are provided. Terms not specifically defined are meant to interpreted as is customary i n the art. As used herein, the term "aerosols" refers to dispersions in air of solid or liquid particles, of fine enough particle size an d consequent low settling velocities to have relative airborne stability (See Knight, V., Viral and Mycoplasmal Infections of th e Respiratory Tract. 1973, Lea and Febiger, Phila. Pa., pp. 2) . "Liposome aerosols" consist of aqueous droplets within which are dispersed one or more particles of liposomes or liposomes containing one or more medications intended for delivery to th e respiratory tract of man or animals (Knight, V. and Waldrep, J. C Liposome Aerosol for Delivery of Asthma Medications; see also I n Kay, B., Allergy and Allergic Diseases, 1997, Blackwell Publications, Oxford, England, Vol. I pp. 730-741). The size of the aerosol droplets defined for this application are those described in U.S. patent 5,049,338, namely mass median aerodynamic diameter (MMAD) of 1-3 μm with a geometric standard deviation of about 1.8-2.2. However, with low concentrations of 9-NC and possibly other camptothecin derivatives, the MMAD may be less than 1 μm, such as 0.8 μm. Based on the studies disclosed by the present invention, the liposomes may constitute substantially all of th e volume of the droplet when it has equilibrated to ambient relative humidity. As used herein, the "Weibel Lung Model" refers to a classification of the structure of the human lungs that recognizes 23 consecutive branchings of the airways of humans. The trachea is labeled 0, bronchi and bronchioles extend through branches 16. These portions of the airways contain ciliated epithelium an d mucus glands. Together they constitute the mucociliary blanket. Branchings 17-23 compose the alveolar portion of the lung and do not have a mucociliary blanket. Thus, particles deposited here are not carried up the airway to be swallowed. As used herein, the terms "20-S-camptothecin" o r "CPT" refers to a plant alkaloid with anti-cancer properties. As used herein, the terms "9-nitro-camptothecin" o r "9-NC", "9-amino-camptothecin" or "9-AC," and "10, 1 1 - methylenedioxy- camptothecin" or "MDC" refer to active anticancer drugs derived from 20-S-camptothecin that are insoluble in water but are soluble in certain lipid solvents. As used herein, the term s "dilauroylphosphatidylcholine" or "DLPC" is a lipid used to formulate liposomes. The present invention is directed to a method for treating cancer, comprising the step of delivering, via small particle aerosol, aqueous dispersions of anti-cancer drugs to th e respiratory tract of an individual in need of such treatment. In a preferred embodiment of this object, the anti-cancer drug is selected from the group consisting of 20-S-camptothecin, 9-nitrocamptothecin, 9-amino-camptothecin and 10, 1 1 -methylenedioxy- camptothecin. Add-itionally, in a preferred embodiment of th e present objective, the delivery of the anticancer drug is performed by a jet nebulizer. Additionally, there is a liposome for delivery of anticancer drugs via small particle aerosols comprising a n anticancer drug and a lipid, wherein the anticancer drug is at a concentration not exceeding about 10% of the total volume of th e preparation and a ratio of the anticancer drug to the suitable solvent is in the range of about 1 : 1 to about 1 :200, preferably in a range of about 1 : 10 to about 1 : 100, and most preferably in a range of about 1 : 10 to about 1 :50 (wt:wt) of the preparation. One specific embodiment of this object includes 9-nitro-camptothecin and dilauroylphosphatidylcholine in a ratio of about 1 : 10 to 1 :50 wt:wt; with a particularly preferred embodiment having a 9-nitrocamptothecin and dilauroyl-phosphatidylcholine of about 1 :50 wt:wt. Taxol is another anti-cancer drug that is lipid soluble and is incorporated easily into a liposome formulation. The optimal ratio for taxol and dilauroylphosphatidylcholine is a ratio of about 1 : 1 to about 1 :200, preferably in a range of about 1 : 10 to about 1 : 100, and more preferably in a range of about 1 :25 to about 1 :40 (wt:wt). A preferred form provides a taxol to DLPC ratio of about 1 :30. Taxol is dissolved in t-butanol without use of DMSO as is used for some camptothecins. The Taxol liposomal preparation is otherwise similar to that of the camptothecins. Further, the present invention is directed to liposomes for delivery of anticancer drugs via small particle aerosols produced by the following steps: dissolving a lipid-soluble anticancer drug in a solvent suitable for dissolving the anticancer drug to produce dissolved anticancer drug; adding the dissolved anticancer drug to a dissolved lipid suitable for formulation and delivery of drugs by aerosol to produce a solution, wherein th e dissolved anticancer drug is at a concentration not exceeding about 10% of the total volume of the solution and a ratio of th e anticancer drug to the suitable solvent is in the range of about 1 : 1 to about 1 :200 of the solution; and freezing and lyophilizing th e solution. At this point, the solution may be stored frozen for later use or dissolved in sterile water to produce a suspension, wherein the concentration of the anticancer drug in the sterile water in th e suspension is no more than about 5.0 mg/ml. A particular embodiment of the present invention provides a liposome produced by the following steps: dissolving a lipid-soluble anticancer drug selected from the group of 20-S-camptothecin, 9 - nitro-camptothecin, 9-amino-camptothecin and 10, 1 1 - methylenedioxy-camptothecin in 100% DMSO to produce dissolved anticancer drug; and adding said dissolved anticancer drug to dilauroylphosphatidylcholine dissolved in t-butanol to produce a solution, wherein the dissolved anticancer drug is at a concentration not exceeding about 5% of the total volume of th e solution and the ratio of anticancer drug to dilauroylphosphatidylcholine is about 1 :50 in the solution. The solution is frozen and lyophilized overnight. For use, th e lyophilized solution is suspended in appropriate volumes of sterile, distilled water. In addition, other methods of liposome preparation known in the art may be utilized, for example, rotary evaporation can be used instead of lyophilization. 9-NC-DLPC aerosol is prepared by first dissolving th e drug in DMSO; to do so, heating to 50-60°C may be required. This solution is added to a larger volume of t-butanol, such that th e DMSO solution does not exceed 5-10% of the total t-butanol and DMSO volume combined. The organic solvents DMSO and t-butanol are evaporated from the solution on liquid nitrogen resulting in a slightly yellow powder. For use, distilled sterile water is added to the vials containing the drug at the appropriate concentration an d added to the reservoir of the nebulizer. The Aerotech II™ nebulizer CIS-USA, Inc., Bedford Ma. is employed, but nebulizers with similar aerosol-generating properties may be used. A particular embodiment of the present invention is directed to a liposome produced by the following steps: mixing taxol with synthetic alpha lecithin: dilauroylphosphatidylcholine; dissolving the taxol-DLPC in t-butanol to produce a solution; and freezing and lyophilizing the solution. Liposomes are produced b y adding sterile, pure water at a temperature above 25°C, wherein the final concentration of taxol to dilauroylphosphatidylcholine is about 1 : 1 to about 1 :200, preferably in a range of about 1 : 10 to about 1 : 100, and more preferably in a range of about 1 :25 to about 1 :40 (wt:wt). It is contemplated specifically that the pharmaceutical compositions of the present invention be used for aerosol delivery of aqueous dispersions of liposomes carrying anti-cancer drugs to the respiratory tract. A person having ordinary skill in this ar t would readily be able to determine, without undue experimentation, the appropriate dosages of these aerosol formulations. When used in vivo for therapy, the aerosol formulations of the present invention are administered to th e patient in therapeutically effective amounts; i.e., amounts that eliminate or reduce the tumor burden. As with all pharmaceuticals, the dose and dosage regimen will depend upon the nature of the cancer (primary or metastatic), the characteristics of the particular drug (e.g., its therapeutic index), the patient, th e patient's history and other factors. The amount of aerosol formulation administered will typically be in the range of about 8 μg/kg of patient weight/day to about 100 μg/kg of patient weight/day for 9-NC. Again, dose and dosage regimen will v ary depending on factors known to those skilled in the art. Se e Remington's Pharmaceutical Sci., 17th Ed. ( 1990) Mark Publishing Co., Easton, Penn.; and Goodman and Gilman's: The Pharmacological Basis of Therapeutics 8th Ed (1990) Pergamon Press. The small particle liposome aerosol compounds and methods of treatment of the present invention involve lipid- o r water-soluble anti-cancer drugs incorporated into liposomes. The liposomes are administered in aqueous dispersions from a j et nebulizer. Various anti-cancer drugs may be used, including 20 - S-camptothecin, 9-nitro-camptothecin, 9-amino-camptothecin, 10, 1 1 -methylenedioxy-camptothecin and taxol. The following examples are given for the purpose of illustrating various embodiments of the invention and are not meant to limit the present invention in any fashion: EXAMPLE 1 Anti-cancer drugs CPT and its 9-NC derivative Representative of the anti-cancer drugs of the pre sent invention are 20-S-camptothecin and its 9-NC derivative. Other camptothecins such as 9-AC and 10, 11-MDC, as well as other anticancer formulations known in the art, also possess properties suitable for use. All these anti-cancer drugs may be used in liposome formulations. Table 1 shows a comparison of blood or plasma concentrations of 9-NC and the time of peak concentrations following oral administration to humans, dogs and mice. (Hinz, H. R., et. al. Pharmacokinetics of the in vivo and in vitro conversion of 9-Nitro 20-(S)-camptothecin to 9-Amino-20-(S)-camptothecin in Humans, Dogs and Mice. Cancer Research 1994 54 : 3096-3 100) . Single oral doses ranged from 0.1 to 1.0 mg/kg for humans an d dogs and were 4.1 mg/kg for mice. There may be some differences in pharmacokinetics between CPT and 9-NC, but it is a reasonable possibility that the foregoing differences are predictive of the properties of both agents. Table 1. Comparison of 9-NC concentrations in blood or plasma following single oral, intranasal or aerosol dosage * Intranasal and aerosol results from Baylor Aerosol Laboratory, the others from Hinz, H.R. (see text for reference) Table 2 describes the method of calculating aerosol dosage in the mouse, and this is the basis for determining dosages cited in Table 1. Much of the inhaled drug is deposited in the nasopharynx of the mouse because of the complex nose structure of rodents. Similarly, nasal instillation leads to high nasopharyngeal deposition. Material deposited here is promptly transported to the esophageal orifice and swallowed. About 1 0 - 1 5 percent of the inhaled aerosol dose, however, will penetrate to th e peripheral lungs. In humans with mouth breathing, only small amounts of the aerosol particles will deposit in the mouth and virtually none will deposit in the nasopharynx. Material deposited in th e central airways is returned to the pharynx by muco-ciliary action where it is swallowed. In the case of primary lung tumors which often occur at bronchial bifurcations, drug will deposit on tumor surfaces and be adsorbed directly into the tumor mass. Material deposited beyond the 16th Weibel generation, which is beyond the ciliated epithelium, will not be moved upward; thus, in tumors within the peripheral lung parenchyma, the drug will deposit in adjacent areas and be absorbed directly into the tumor mass. I n addition, a major advantage of the present invention is that drug deposited beyond the ciliated epithelium is picked up b y capillaries in the interstitial space and the lymphatics of the lungs and will enter the circulation. Table 3 shows the tissue distribution of CPT following 15 minutes of nebulization in DLPC liposome aerosol. The deposited dose was calculated to be 486 ng per mouse. The me an concentrations in lungs and liver were similar with smaller concentrations in the other sites examined. Table 4 shows tissue distributions over a period of one hour following intranasal instillation of 7 μg per mouse (233 μg/kg). Drug was cleared promptly from the lungs so that by 15 minutes after stopping nebulization only negligible amounts of drug were present in th e lungs. Liver, kidney and spleen had substantial amounts of drug initially which gradually diminished through the one hour of study. Interestingly, blood concentrations were the least throughout the study. These studies indicate substantial immediate deposition of drug in the lungs with rapid clearance to the viscera. The amount of drug contributed by absorption from swallowed drug is uncertain. Table 3. Tissue distribution of CPT following 15 minutes inhalation of CPT liposome aerosol The CPT concentration in the liposomal preparation m the nebulizer was 0 2 mg/ml aerosol was generated with an Aerotech II nebulizer operating at a flow rate of 10 L/min Table 4. Time dependent organ distribution of CPT after intranasal administration Lung 1287 ±657 19± 3 36 ±23 7± 3 Liver 651 ±418 255 ±101 66 ±17 34 ± 7 Kidney 542 ±174 190 ± 57 49 ±13 24 ±21 Spleen 351 ±137 84 ± 32 21 ± 8 7± 2 Blood 213 ± 19 53 ± 20 8± 3 4± 2 Remarks: CPT was administered in liposomal formulation prepared with DLPC with initial drug concentration 0.2 mg/ml. 35 μL of suspension was installed to each animal (group of 3 animals was treated for each time point). Table 5 shows the distribution of drug in blood an d viscera following intramuscular injection of CPT. Drug disappeared very slowly from the site of intramuscular injection in the first 12 hours, with only very small concentrations detected in the liver and virtually no drug present at other sites. Concentrations in the blood were negligible throughout the study. The dose administered was the same as that given by intranasal instillation. These findings indicate a speedier and more efficient systemic absorption of drug after pulmonary administration of drug than by the intramuscular route. It is likely that deposition in organs and vascular spaces will increase the opportunity for exposure to albumin molecules and degradation to the i form of the drug. Table 5. Time dependent organ distribution of CPT after intramuscular administration Remarks: CPT initial stock 5 mg/ml in DMSO was suspended in saline (1.4 μL stock + 48.6 μL saline; and total 50 μL of suspension was injected i.m. in each mice. Group of 3 animals was treated for each time point. EXAMPLE 2 Stability of Liposomes Consisting of DLPC and 9-AC Table 6 shows the stability of liposomes with fixed weight ratio of 9-NC and DLPC of 1 :50 (w/w) but with increasing concentrations of constituents from 0.1 mg/ml to 1.0 mg/ml of drug. The samples were tested under various conditions after vortexing, but before start of nebulization, after nebulization for 1.5 to 2 minutes (sample taken from the fluid in the reservoir of the nebulizer) and from the aerosol that was collected in an all- glass impinger (All-Glass Impinger, Ace Glass Co., Vineland N. J.). Table 6. Liposome particle size and drug crystal formation in preparations of 9-NC DLPC liposome formulations The most stable preparation was the one with lowest concentration of constituents. A few crystals appeared in th e reservoir following nebulization. Nebulization caused a ten-fold reduction in the diameter of the liposome particles, due to th e shear forces associated with nebulization. There was further reduction in the diameter of liposome particles recovered from th e aerosol. This finding is consistent with selection of smaller particles for discharge in aerosol. The lack of crystals suggests that crystals may not nebulize as readily as liposomes. With larger dosages of liposomes, size reduction following nebulization occurred, but particles recovered from aerosol were not reduced in size compared to particles that had been cycled in the reservoir of the nebulizer. EXAMPLE 3 Kinetics of Lactone Ring Opening The anti-tumor activity of several of the camptothecins are diminished following dissolution in aqueous media. This is due to a hydrolyzable alpha-hydroxy lactone ring (ring E). The change results from acyl cleavage yielding the biologically inactive carboxylate form of the molecule. The lactone ring form of th e drug is sheltered in liposomes (Burke, T. G., Biochemistry 1 993 32:5352-5364), but the carboxyl form of the drug has high affinity for human serum albumin. This leads to rapid conversion of lactone to carboxylate in the presence of human s erum albumin, and thus to loss of anti-cancer activity. Deposition within the lungs on alveolar surfaces where there is little albumin and/or interaction with constituents of the liposomes is clearly a factor in preserving the anti-cancer effect of 9-NC. EXAMPLE 4 Effect of 9-NC on Growth of Human Breast Cancer Explants in Mice Figure 1 shows growth in the area of subcutaneous breast cancer xenografts during treatment with 9-NC-DLPC liposome aerosol. There were six 9-NC treated and 5 control mice. Treatments were given 15 minutes daily, five days per week. The dose was 8.1 μg/kg per day. The deposited dose in th e respiratory tract of each mouse was estimated to be 234 ng p e r day. The data on tumor size was normalized and the divergence of tumor size (% initial tumor growth) in the two groups w a s highly significant by day 17 of treatment (P<0.011). After thi s time, control mice were sacrificed because of the presence of large necrotic tumor masses. Figure 2 shows the course of events with two treated mice which were subsequently followed with higher doses of drug, following a period of 16 days without treatment. A few days following restart of treatment with a fivefold increase in the dose of 9-NC liposome aerosol, the size of tumors in the treated animals diminished rapidly, and were no longer visible by the 85th day after start of treatment. EXAMPLE 5 Effect of 9-NC on Human ColoRectal Cancer Xenografts in Mice A similar study was performed in nude mice with human colon carcinoma xenografts and is shown in Figure 3. There were 15 treated and 20 control mice. Ten controls received empty DLPC liposomes and 10 received no treatment. Control animals who received no treatment or DLPC only showed a consistent and rapid increase in tumor size until they w ere sacrificed on day 36. The overall rate of tumor growth was 7 to 11 times greater in control than in 9-NC-treated mice. The treated animals were divided into two groups of 10 each. One group received 77 μg/kg/daily, five days per week throughout the entire experiment. The other received 77 μg/kg per day five days p er week until day 35 when the dose was increased to 153 μg/kg p er day five days per week until day 46 when it was increased to 307 μg/kg on the same schedule until day 61. There was slightly less increase in tumor size in the group receiving the higher dose, b u t the differences were not statistically significant, and the data are combined in the figure. Four mice in the DLPC treatment group were sacrificed because of large tumors or tumor necrosis before day 61 , and six mice in the no treatment group were sacrificed for the same reasons before day 61. In the treatment group five mice were sacrificed because of tumor necrosis or emaciation before day 61. The emaciated mice were in the high dose group, suggesting drug toxicity. One additional treated mouse w as sacrificed because of rectal prolapse. Based on these findings of reduced rate of tumor growth, day 28, (P<0.007, Student t test, 2 tailed) and reduced mortality there is an unequivocal therapeutic effect of 9-NC treatment (P<0.002~chi square test). EXAMPLE 6 Effect of 9-NC on Human Lung Carcinoma Xenografts in Nude Mice Additionally, studies were performed on the effect of treatment with 9-NC-DLPC via liposome aerosol or via oral administration on the growth of human lung cancer xenografts (Spark) in nude mice as measured by tumor volume. Treatment was initiated about two weeks after tumor implantation. Control animals showed a rapid increase in volume of tumors. Animals who received oral dosage with the liposome drug aqueous suspension in doses of 100 μg/kg/day--more than twice the aerosol dosage—did not respond to treatment. See Figure 4. Both aerosol and oral doses were doubled on day 1 3. The increased dosage was followed by decrease in the size of tumors treated with aerosol, but there was no decrease in size of tumors in mice given oral treatment. Thus, despite the fact th at half or more of aerosol dosage administered to mice is deposited in the nose, head, trachea and upper bronchi and is promptly carried by the mucociliary system to the esophagus where it i s swallowed, the fraction of inhaled drug that is deposited in th e lung is principally responsible for the effect on tumor growth. The most likely explanation of the clear efficiency of aerosol delivery is the rapid entry of the drug to the circulation where it is returned to the left heart, and then to the aorta and peripheral circulation. Thus, the drug would reach the tumors on "first pass" without having passed through the liver, which would remove large amounts of drug from blood. EXAMPLE 7 Animal Models Nude Mice: Swiss immunodeficient nude mice of th e NIH-1 high fertility strain, bred and housed at the Stehlin Institute were used for these experiments (Giovella, B.C., et al., Complete Growth Inhibition of Human Cancer Xenografts in Nude Mice by Treatment with 20-(S)-Camptothecin, Cancer Research 1991 51 : 3052-3055). Human Cancer Xenografts: Human heterotransplants w ere established in nude mice. For an implant, approximately 50 m g of wet weight of finely minced tumor in 0.5 ml of Eagles minimum essential medium was injected under the skin over th e right dorsal chest region. The animals were started on treatment with the experimental drug about 10 days after implantation of tumors. Tumors of breast cancers were measured in two dimensions (i.e. area) with calipers, while colon cancers w ere measured in three dimensions (i.e. volume) with calipers. EXAMPLE 8 Camptothecin Liposome Aerosol Formulation and Administration CPT and 9-nitrocamptothecin were provided by Dr. Beppino Giovanella of the Stehlin Institute, Houston, Texas. DLPC was obtained from Avanti Polar Lipids, Pelham, AL. Aerotech 1 1 nebulizers were obtained from Cis-USA, Inc., Bedford, MA. For formulation of liposomes, 9-NC (100 mg/ml) or CPT (10 mg/ml) was dissolved in 100% DMSO, and added to DLPC dissolved in tertiary butanol (40°C) so the final DMSO concentration did not exceed 5 percent of the total volume and the ratio of drug to lipid was 1 :50 (w/w). The final suspension w a s clear. If precipitation occurred, it was reheated to 50-60°C. The preparation was frozen in liquid nitrogen and lyophilized overnight. For use the material was dissolved in sterile water to the appropriate drug concentration, not exceeding 1.0 mg/ml for either drug. The efficiency of incorporation of drug in th e liposomes was examined qualitatively by microscopic examination under polarized light. Unincorporated drug was seen as bi- refringent crystals. The efficiency of incorporation was examined by centrifugation of aqueous suspensions of liposomes on Percoll™ gradients. One-tenth ml of suspension was layered over 2 ml of gradient and centrifuged at 2000 rpm for 25-30 minutes . Liposomes layer at the water-Percoll interface, while unincorporated drug was deposited at the bottom of the tube . Many other lipids may be substituted for DLPC in the formulation and use of liposomes for delivery of drugs by aerosol (Sugarman, S. M., et. al. Lipid-complexed campothecin: formulation and initial biodistribution and anti-tumor activity studies. Cancer Chemotherapy Pharmacol. 1996 37:531 -538). EXAMPLE 9 HPLC Analysis The Waters (Milford, MA) 710B Wisp automatic injector and Waters Nova-Pak C18 column at room temperature was used to quantitate CPT and 9-NC. The mobile phase was 30% acetonitrile and 70% of 0.1% glacial acetic acid. CPT was detected using the Waters 470 scanning fluorescence detector set to a n excitation wavelength of 370 nm and an emission wavelength of 440 nm. 9-NC was detected using the Waters 440 absorbence detector and monitoring at 254 nm. The data were analyzed with the Waters Millenium software. EXAMPLE 10 Aerosol Droplet Measurement The size of aerosol droplets was measured with th e Andersen ACFM non-viable ambient particle sizing sampler (Andersen Instruments, Inc., Atlanta, Ga.) by methods previously described (Waldrep, J. C. et. al.. J Aerosol Med. 1994 7 : 135- 145) . Mass median aerodynamic diameters and geometric standard deviations were determined using KaleidaGraph 2.0 (Synergy Software, Reading Pa.). The aerosol droplets consisted of a n aqueous suspension of liposomes. Liposome diameters w ere measured in aqueous suspension with the Model 3300 NICOMP Laser Particle Sizer. EXAMPLE 11 Preparation and Efficiency of Taxol-DLPC Liposomes Formulated by Aerosol Delivery Taxol is another anti-cancer drug that is lipid soluble and is incorporated easily into liposomal formulation. Taxol is dissolved directly in t-butanol without use of DMSO similar to th e camptothecins. The taxol liposomal preparation is otherwise like that of the camptothecins. The optimal taxol to DLPC ratio was found to be about 1 :30 wt:wt. Formulations compatible with nebulization and aerosol delivery formulations were produced at 1 mg Taxol and with 30 mg DLPC per ml. For optimized Taxol-DLPC liposomes, 5 mg of Taxol was mixed with 150 mg of synthetic alpha-lecithin: dilauroylphosphatidylcholine (DLPC). Working at 37°C, th e drug/DLPC was mixed in 20 mis of tertiary butanol with stirring. After mixing, the drug/lipid preparation was pipetted into glass vials, frozen rapidly, and lyophilized overnight to remove the t - butanol leaving a powder. Multi-lamellar liposomes w ere produced by adding 5 mis of ultra pure water above the DLPC phase transition temperature (Tc) at 25°C to deliver a final standard drug concentration of 1 mg Taxol: 30 mg DLPC per ml. The mixture was incubated for 30 minutes at room temperature with intermittent mixing to produce multilamellar vesicular (MLV) liposomes. Aliquots were removed for determination of drug concentration by HPLC. Figure 5 shows the particle size distribution of taxol- DLPC liposome aerosol with a MMAD of 1.4 μm and a geometric standard deviation of 2.0 Figure 6 shows the recovery of taxol from the preparation described in Figure 5. In the lung model (Harvard Respirator) used to measure the output of taxol from th e nebulizer (Aerotech II), 87.75 liters of aerosol were sampled yielding 3000 μg of taxol. There was thus an aerosol concentration of 34.2 μg/1. From this information, the dose of aerosol deposited in the respiratory tract following inhalation can be calculated. Any patents or publications mentioned in this specification are indicative of the levels of those skilled in the ar t to which the invention pertains. Further, these patents an d publications are incorporated by reference herein to the s ame extent as if each individual publication was specifically and individually indicated to be incorporated by reference. One skilled in the art will appreciate readily that th e present invention is well adapted to carry out the objects an d obtain the ends and advantages mentioned, as well as those objects, ends and advantages inherent herein. The present examples, along with the methods, procedures, treatments , molecules, and specific compounds described herein are presently representative of preferred embodiments, are exemplary, and are not intended as limitations on the scope of the invention. Changes therein and other uses will occur to those skilled in the art which are encompassed within the spirit of the invention as defined b y the scope of the claims.

Claims: WHAT IS CLAIMED IS: 1 . A method for treating cancer, comprising th e step of delivering, via small particle aerosol, aqueous dispersions of anti-cancer drugs in liposomes to the respiratory tract of a n individual in need of such treatment. 2. The method of claim 1, wherein said anti-cancer drug is selected from the group consisting of 20-S-camptothecin, 9-nitro-camptothecin, 9-amino-camptothecin, 10, 1 1 - methylenedioxy-camptothecin, taxol, taxol-A, mitotane, methotrexate, mercaptopurine, lomustine, interferon, 5 - fluorouracil and etopiside. 3. The method of claim 2, wherein said anti-cancer drug is selected from the group consisting of 20-S-camptothecin, 9-nitro-camptothecin, 9-amino-camptothecin, 10, 1 1 - methylenedioxy-camptothecin and taxol. 4. The method of claim 1, wherein said delivering step is performed by a jet nebulizer. 5. The method of claim 4, wherein said liposomes are sheared to a diameter of less than 500 nm by said j et nebulizer. 6. The method of claim 1, wherein a final concentration of said anticancer drug in said liposomes is no greater than 5.0 mg/ml. 7. The method of claim 6, wherein a final concentration of said anticancer drug in said liposomes is no greater than 1.0 mg/ml. 8. A liposome for delivery of anticancer drugs via small particle aerosol, wherein a ratio of anticancer drug to lipid is about 1 : 1 to about 1 :200 wt:wt. 9. The liposome of claim 8, wherein a ratio of anticancer drug to lipid is about 1 : 10 to about 1 : 100 wt:wt. 10. The liposome of claim 9, wherein a ratio of anticancer drug to lipid is about 1 : 10 to about 1 : 50 wt:wt. 1 1 . The liposome of claim 8, wherein said anticancer drug is camptothecin or a derivative of camptothecin, said lipid is dilauroylphosphatidylcholine, and said ratio is about 1 : 10 to about 1 :50. 12. The liposome of claim 8, wherein said anticancer drug is taxol or its derivatives, said lipid is dilauroylphosphatidylcholine and said ratio is about 1 :25 to about 1 :40. 13. A liposome produced by the following steps: dissolving a lipid-soluble anticancer drug in a n appropriate solvent to produce dissolved anticancer drug; dissolving a lipid suitable for the formulation an d delivery of anticancer drugs by aerosol in an appropriate solvent to produce dissolved lipid; combining said dissolved anticancer drug and said dissolved lipid to produce a solution, wherein said dissolved anticancer drug is at a concentration not exceeding about 10% of the total volume of said solution and a ratio of said anticancer drug to said suitable lipid is in a range of 1 : 1 to 1 :200 wt:wt of said solution; and evaporating said solvents from said solution to produce a powder. 14. The liposome of claim 13, further comprising th e step of dissolving said powder in sterile water to produce a suspension, wherein a concentration of said anticancer drug in said sterile water is no more than about 5.0 mg/ml. 15. The liposome of claim 13 wherein said suitable lipid for formulating and delivering drugs by aerosol is dilauroylphosphatidylcholine. 16. The liposome of claim 13, wherein said anticancer drug is selected from the group consisting of 20- S - camptothecin, 9-nitro-camptothecin, 9-amino-camptothecin, 10, 11-methylenedioxy-camptothecin, taxol, taxol-A, mitotane, methotrexate, mercaptopurine, lomustine, interferon, 5 - fluorouracil and etopiside. 17. The liposome of claim 13, wherein said anticancer drug is selected from the group consisting of 20- S - Camptothecin, 9-Nitro-camptothecin, 9-Amino-camptothecin and 10, 11-methylenedioxy-camptothecin, and taxol. 1 8. The liposome of claim 13, wherein a ratio of anticancer drug to lipid is about 1 : 10 to about 1 : 100 wt:wt. 19. The liposome of claim 18, wherein a ratio of anticancer drug to lipid is about 1 : 10 to about 1 : 50 wt:wt. 20. A liposome produced by the following steps: dissolving a lipid-soluble anticancer drug selected from the group of 20-S-camptothecin (CPT), 9-nitrocamptothecin (9-NC) and other lipid soluble camptothecin derivatives in a volume of DMSO to produce dissolved anticancer drug; mixing said dissolved anticancer drug with a n appropriate solvent; dissolving a lipid suitable for the formulation and delivery of drugs by aerosol in an appropriate solvent to produce a dissolved lipid; combining said dissolved anticancer drug and said dissolved lipid to produce a solution, wherein said DMSO is at a concentration not exceeding about 10% of the total volume of said solution and a ratio of said anticancer drug to said suitable lipid is in a range of 1 : 1 to 1 :200 of said solution; and evaporating said solvents from said solution to produce a powder. 21 . The liposome of claim 20, wherein said lipid is dilauroylphosphatidylcholine.

Inventors: GILBERT BRIAN, GIOVANELLA BEPPINO, KNIGHT J VERNON, KOSHKINA NADEZHDA, WALDREP J CLIFFORD, WELLEN C W, GILBERT, BRIAN, GIOVANELLA, BEPPINO, KNIGHT, J., VERNON, KOSHKINA, NADEZHDA, WALDREP, J., CLIFFORD, WELLEN, C., W.
Applicants: RES DEV FOUNDATION, RESEARCH DEVELOPMENT FOUNDATION
Application year: 1998
Main classification: A61K9
IPC codes: A61K9, A61K31, A61K38, A61K45, A61P35