Patent Application
20070154494
This application claims priority to U.S. provisional application No. 60/446,995, filed Feb. 13, 2003 and U.S. provisional application No. [attorney docket no. 7767-190653], filed Jul. 14, 2003, which are incorporated by reference herein in their entirety.
The invention relates to immunogenic anthrax compositions, such as anthrax vaccines, and/or to methods for delivering anthrax compositions or vaccines.
In light of the events of Sep. 11, 2001 and the anthrax scare in the following months, it has become increasingly clear that there is an urgent need for new biodefense vaccines to protect both military and civilian populations. Such new vaccine development may proceed in tandem with the development of novel delivery platforms in order to improve the efficacy of the candidate vaccines and to ensure safe and rapid deployment in the event of a national emergency.
The virulence of Bacillus anthracis, the causative agent of anthrax, is mediated by three main protein components: the protective antigen (PA), the lethal factor (LF) and the edema factor (EF). While these proteins are non-toxic individually, in combination they form a potentially lethal toxin. Cutaneous exposure to anthrax spores causes a skin lesion that typically responds well to antibiotic treatment. Inhalation anthrax, however, represents a much more formidable threat. Early diagnosis of inhalation anthrax is difficult and the disease often manifests abruptly as respiratory failure or hemodynamic collapse 2-4 days after the initial onset of symptoms.
The currently licensed vaccine in the United States is the Anthrax Vaccine Absorbed (AVA), which consists of a culture filtrate of a toxigenic, non-encapsulated strain of B. anthracis, absorbed onto aluminum hydroxide as adjuvant. While generally effective in providing protection against anthrax in humans, the current vaccine is administered in a 6-dose series over 18 months followed by yearly boosters thereafter. Thus, there is a need to produce safer and more potent anthrax vaccines, e.g., in order to reduce the number of required doses to achieve protective immunity.
A recently developed candidate anthrax vaccine is based on a recombinantly produced PA (Ivins, B. E., Infection and Immunity, 60:662-668, 1992; Ramirez, D. M., et al., J. Industrial Microbiol. and Biotechnol. 28:232-238, 2002). This vaccine is being investigated by USAMRIID as an alternative to AVA due to the potential for improved efficacy and thus a reduction in the required number of booster administrations, as well as an improved safety profile. Additional pre-clinical and clinical studies are required in order to determine the most effective delivery routes for protection and to further elucidate the potential requirements for adjuvants. Adjuvants such as alum are often associated with skin reactions and other adverse events; thus, a preferred vaccine would retain the immunogenicity of the alum-containing vaccine but would not have the associated side effects.
The present invention provides immunogenic anthrax compositions, such as anthrax vaccines, and methods for delivering anthrax compositions or vaccines to a patient in need thereof.
One embodiment of the invention is an immunogenic anthrax composition (e.g., an anthrax vaccine) in particulate form, which is suitable for intranasal administration. Such a composition can be made by methods described herein and/or exhibits properties described herein, preferably comprising particles having a volume mean diameter of between about 35 μm and about 300 μm, wherein at least about 50% of said dried particles have a volume diameter within about 80% of the mean, and wherein said dried particles have a mean aerodynamic diameter of between about 8 μm and about 140 μm.
Other embodiments of the invention include methods of delivering an immunogenic anthrax composition intranasally, intradermally (e.g. using hollow microneedles) and by topical-abrasion (e.g. using solid microneedles).
Compositions and methods of the invention exhibit several advantages. For example, they improve the immunogenicity and protective efficacy of vaccines; may reduce or eliminate the need for adjuvants in vaccine formulations; provide for minimally-invasive administration of vaccines; and/or enable self-administration of vaccines. In a preferred embodiment, the vaccine is a biodefense vaccine, more preferably an anthrax vaccine, and most preferably an anthrax rPA vaccine.
According to the present invention, the terms “improve”, “improved” and “improvements” in reference to a vaccine are intended to mean that the vaccine stimulates a stronger immune response (i.e., provides increased immunogenicity) than that achieved via conventional formulations and/or via conventional routes of administration of the vaccine. Conventional formulations include, e.g., rPA in alum; and conventional routes of administration include, e.g., intramuscular [IM] or subcutaneous [SC]) delivery. The terms “improve”, “improved” and “improvements” in this context can also mean that the vaccine stimulates a stronger protective immune response than that achieved via conventional formulations administered via conventional routes of delivery; and/or that the vaccine requires a reduced number of immunizations to achieve an immune response than that required for the conventional formulations administered via conventional routes; and/or that the vaccine requires a reduced number of immunizations to achieve a protective immune response than that required for conventional formulations administered via conventional routes.
In one aspect, the invention includes an immunogenic anthrax composition (e.g., an anthrax vaccine, or a pharmaceutical composition) in particulate form, which is suitable for delivery to a patient intranasally, and to methods for making and using such a composition. For example, one embodiment is an immunogenic anthrax composition in the form of dried particles made by a method comprising one or more of the following steps:
In preferred embodiments of this aspect of the invention, the immunogenic anthrax composition is an anthrax vaccine, preferably an Anthrax Vaccine Absorbed (AVA) vaccine, more preferably a recombinant protective antigen (rPA) vaccine. The immunogenic anthrax composition may or may not comprise an adjuvant.
In one preferred embodiment, the dried particles have a volume mean diameter of between about 35 μm and about 300 μm, wherein at least about 50% of the dried particles have a volume diameter within about 80% of the mean, and wherein said dried particles have a mean aerodynamic diameter of between about 8 μm and about 140 μm.
In another preferred embodiment, the dried particles of the immunogenic anthrax composition have a volume mean diameter of between about 501 μm and about 300 μm, more preferably between about 50 μm and about 100 μm, and/or the dried particles have a mean aerodynamic diameter of between about 201 μm and about 70 μm.
With regard to this method of making the immunogenic anthrax composition (e.g., anthrax vaccine), the freezing may be performed by introducing the atomized formulation into a fluid or medium having a temperature below the freezing point of the liquid formulation; wherein preferably the fluid or medium has a boiling point or sublimation point lower than that of said atomized formulation. The fluid may be a gas or a liquid. The particles may be dried by lyophilization; or at about atmospheric pressure, in the presence of vibration, internals, mechanical stirring, or a combination thereof and are, optionally, further dried by lyophilization. The liquid formulation may comprise a mucoadhesive, e.g., chitosan, dermatan sulfate, chondroitin, or pectin. In one embodiment, the liquid formulation of the anthrax composition consists essentially of said anthrax composition and water.
The invention also includes an immunogenic anthrax composition (e.g., an anthrax vaccine) prepared by atomizing a liquid formulation of an immunogenic anthrax composition to produce an atomized formulation, such that, following freezing of said atomized formulation to form solid particles, and drying of said solid particles to produce dried particles, said dried particles have an average mean diameter of between about 35 μm and about 300 μm, at least about 50% of said dried particles have a volume diameter within about 80% of the mean, and said dried particles have a mean aerodynamic diameter of between about 8 μm and about 140 μm.
The invention also includes an immunogenic anthrax composition (e.g., an anthrax vaccine) that comprises dried particles having a mean aerodynamic diameter of between about 8 μm and about 140 μm and a volume mean diameter of between about 35μ and about 300μ, wherein at least about 50% of said dried particles have a volume diameter within about 80% of the mean, and a pharmaceutically acceptable carrier. This immunogenic anthrax composition may be an anthrax vaccine, e.g., an AVA vaccine or, preferably, an rPA vaccine.
Furthermore, the invention includes an immunogenic anthrax composition (e.g., an anthrax vaccine) made by a method comprising
In another aspect, the invention provides a method of preparing an immunogenic anthrax composition (e.g., an anthrax vaccine). One preferred embodiment of this aspect of the invention is a method of preparing an immunogenic anthrax composition comprising
Another embodiment of this aspect of the invention is a method for preparing an immunogenic anthrax composition (e.g., an anthrax vaccine), comprising atomizing a liquid formulation of an immunogenic anthrax composition to produce an atomized formulation, such that, following freezing of said atomized formulation to form solid particles, and drying of said solid particles to produce a powder, the dried powder comprises dried particles having an average mean diameter of between about 35μ and about 300μ, at least about 50% of said dried particles have a volume diameter within about 80% of the mean, and said dried particles have a mean aerodynamic diameter of between about 8 μm and about 140 μm.
A further aspect of the invention is a method for delivering an immunogenic anthrax composition (e.g., an anthrax vaccine) to a mammal, comprising administering to the mammal an effective amount of an immunogenic anthrax composition of the invention. Preferably, the immunogenic composition is an anthrax vaccine, e.g., an Anthrax Vaccine Absorbed (AVA) vaccine or a recombinant protective antigen (rPA) vaccine. The anthrax composition may additionally comprise an adjuvant, but is preferably adjuvant-free. The immunogenic anthrax composition may be administered intranasally, and/or to a mucosal membrane.
This aspect of the invention includes a method for reducing the amount of an immunogenic anthrax composition (e.g., an anthrax vaccine) that is required to produce an efficacious result following intranasal administration to a patient in need thereof, comprising administering to said patient, intranasally, an effective amount an immunogenic anthrax composition of the invention.
A further embodiment of the invention is a method for eliciting (inducing) an immune response in a patient, comprising administering (e.g., intranasally) to said patient an effective amount of an immunogenic anthrax composition of the invention. A particularly preferred embodiment is a method of vaccinating a patient against anthrax, comprising administering to said patient an effective amount of an anthrax vaccine of the invention. In one embodiment, the anthrax vaccine is administered as part of a prime-boost regimen. Suitable prime-boost regimens are familiar to those of skill in the art and can be determined by routine experimentation.
The invention also provides an intradermal (ID) method for delivering an immunogenic anthrax composition (e.g., an anthrax vaccine) to a mammal, using a hollow microneedle (HMN). Accordingly, the invention includes a method for delivering an immunogenic anthrax composition (e.g., an anthrax vaccine, such as an Anthrax Vaccine Absorbed (AVA) vaccine, or, preferably, a recombinant protective antigen (rPA) vaccine) to a mammal, comprising intradermally administering the composition through at least one hollow needle having an outlet with an exposed height between 0 and 1 mm, said outlet being inserted into the skin to a depth of between 0.5 mm and 2 mm. The immunogenic anthrax composition so used may or may not comprise an adjuvant.
In one embodiment of this intradermal administration method, the immunogenic anthrax composition is administered with a device comprising
a hub portion being attachable to a prefillable reservoir storing the vaccine;
at least one hollow microneedle supported by said hub portion and having a forward tip extending away from said hub portion; and
a limiter portion surrounding said microneedle(s) and extending away from said hub portion toward said forward tip of said microneedle(s), said limiter including a generally flat skin engaging surface extending in a plane generally perpendicular to an axis of said microneedle(s) and adapted to be received against the skin of a mammal to administer an intradermal injection of the vaccine, said microneedle(s) forward tip(s) extending beyond said skin engaging surface a distance approximately 0.5 mm to 2.0 mm wherein said limiter portion limits penetration of the microneedle(s) into the dermal layer of skin of the mammal. In embodiments of this method, delivery of the immunogenic composition occurs at a depth between 0.025 mm and 2.5 mm in the skin of the mammal; the delivered immunogenic composition induces an immune response in the mammal that is equal to or greater than the response after delivery of the same amount of immunogenic composition by subcutaneous or intramuscular injection; the delivered immunogenic composition induces an immune response in the mammal that is equal to or greater than the response after delivery of a greater amount of the immunogenic composition by subcutaneous or intramuscular injection. Preferably, the needle is a microneedle between about 31 to 50 gauge, perpendicularly inserted into the skin to a depth of between 0.3 and 1.7 mm. In one embodiment of this delivery method, an anthrax vaccine is administered as part of a prime-boost regimen.
In yet another embodiment, the invention provides a method for improving the immunogenicity of an anthrax composition, comprising intradermally administering an effective amount of the anthrax composition through at least one hollow needle. Preferably, the needle has an outlet with an exposed height between 0 and 1 mm, the outlet being inserted into the skin to a depth of between 0.5 mm and 2 mm. Using this and similar means of intradermal administration, the protective efficacy of an anthrax vaccine is improved.
The invention also includes a method for eliciting (inducing) an immune response in a patient (or of vaccinating a patient against anthrax), comprising administering intradermally to the patient an effective amount of an immunogenic anthrax composition (or an anthrax vaccine). In a preferred embodiment of this method, the composition is administered through at least one hollow needle having an outlet with an exposed height between 0 and 1 mm, said outlet being inserted into the skin to a depth of between 0.5 mm and 2 mm.
This invention also relates to a method for topically delivering an immunogenic anthrax composition (e.g., an anthrax vaccine) into skin, comprising abrading the skin with a solid microneedle (SMN) microabrader, and applying the immunogenic composition either before, during, or following the microabrasion step. This delivery method is sometimes referred to herein as a “topical-abrasion” method, and is described, inter alia, in U.S. application No. 10/282,231.
In one embodiment of this method, an immunogenic anthrax composition (e.g., an anthrax vaccine, such as an Anthrax Vaccine Absorbed (AVA) vaccine, or, preferably, a recombinant protective antigen (rPA) vaccine) is delivered by pre-abrading the skin before topical application of the anthrax composition. The anthrax composition delivered according to this method optionally comprises an adjuvant. The skin is preferably abraded at least twice, more preferably at least six times, even six to twelve times or more. The skin may be abraded in alternating directions or the same direction. The immunogenic composition is preferably applied to the skin in liquid form, and may be applied to an abrading device, such as a coated device, or one containing a reservoir for liquids, or may be applied separately, either before or after the abrasion step. In one embodiment, a dry immunogenic composition is reconstituted simultaneously with abrasion. This may be accomplished by having the immunogenic composition present as a powder or other solid on an abrading surface of an abrading device, with a reconstituting liquid separately applied to the skin prior to abrading, or simultaneously with abrading. In one preferred embodiment, the skin is abraded using a device comprising a solid microneedle array.
In one embodiment of the microabrasion method, the skin is abraded with a device that comprises an abrading surface comprising frustoconical or frustopyrimidal microprotusions that comprise at least one scraping edge projecting from the abrading surface. In particular embodiments of this method, the microprotrusions are at least partially coated with the anthrax vaccine; these microprotrusions being of a length sufficient to penetrate into the stratum corneum layer of the skin.
This invention also relates to kits for implementing any of the methods of the invention. For example, one embodiment is a kit comprising an effective amount of an immunogenic anthrax composition (e.g., an anthrax vaccine) in particulate form of the invention and, optionally means to administer the immunogenic composition intranasally.
Another embodiment of the invention is a kit for intradermal delivery of an immunogenic anthrax composition (e.g., an anthrax vaccine). For example, the kit may comprise (a) a delivery device having at least one hollow microneedle designed to intradermally deliver a substance to a depth between 0.025 and 2.5 mm, said delivery device comprising or being adapted to receive a reservoir that contains an anthrax composition such that the microneedle is in communication therewith, and (b) an effective amount (dosage) of the anthrax composition. In embodiments of this kit, the dosage is contained in a reservoir that is an integral part of, or is capable of being functionally attached to, the delivery device; the hollow microneedle is between about 31 to 50 gauge; or the device comprises an array of microneedles.
In one embodiment of this kit, the device comprises (a) a hub portion being attachable to a prefillable reservoir storing the vaccine; (b) at least one microneedle supported by said hub portion and having a forward tip extending away from said hub portion; and (c) a limiter portion surrounding said microneedle and extending away from said hub portion toward said forward tip of said microneedle, said limiter including a generally flat skin engaging surface extending in a plane generally perpendicular to an axis of said microneedle and adapted to be received against the skin of a mammal to administer an intradermal injection of the anthrax composition, said microneedle forward tip extending beyond said skin engaging surface a distance approximately 0.5 mm to 2.0 mm wherein said limiter portion limits penetration of the microneedle into the dermal layer of skin of the mammal.
In another embodiment, the kit comprises (a) a dermal access means designed to intradermally deliver an anthrax composition to a depth between 0.025 and 2.5 mm, said dermal access means being adapted to receive a reservoir that contains the anthrax composition such that the dermal access means is in communication therewith, and (b) an effective amount (dosage) of the anthrax composition.
Another embodiment of the invention is a kit for delivery of an immunogenic anthrax composition (e.g., an anthrax vaccine) comprising use of a microabrader. For example, in one embodiment, the kit comprises (a) a microabrader comprising an abrading surface, wherein the abrading surface comprises frustoconical or frustopyramidal microprotrusions comprising at least one scraping edge and projecting from said abrading surface, and (b) an effective amount of an anthrax composition. In embodiments of this kit, the anthrax composition is coated on the surface of the microabrader; the anthrax composition is contained in a reservoir integrated with the microabrader; or the anthrax composition is separately packaged within the kit.
Yet another embodiment of the invention is a kit for the delivery of an immunogenic anthrax composition (e.g., an anthrax vaccine) to nasal mucosa, including the particulate or powder immunogenic anthrax composition of the invention and means for delivery. Suitable delivery devices are known in the art, for example, a single dose of medicament in powder form can be delivered intranasally using a device which allows storage of the medicament in a cartridge having burstable or pierceable membranes covering the opposed ends. Such devices can be actuated by either bursting or mechanically piercing these membranes, and expelling the medication by passage of a fluid through the cartridge. Devices of this type are described in U.S. patent application Ser. Nos. 09/879,714 (filed Jun. 12, 2001) and 09/758,776 (filed Jan. 12, 2001).
Other optional elements of a kit of the invention include suitable buffers, media components, or the like; containers; or packaging materials. The reagents of the kit may be in containers in which the reagents are stable, e.g., in lyophilized form or stabilized liquids. The reagents may also be in single use form, e.g., in single dosage form for use as vaccines.
Anthrax Compositions
Immunogenic anthrax compositions of the invention can take any suitable form. For example, the composition can comprise a mixture of several anthrax proteins, such as the mixture found in the AVA vaccine, or it can comprise isolated or purified individual components of the anthrax bacterium. Preferably, the vaccine consists essentially of just one of the anthrax proteins (e.g., a recombinant protein), most preferably the protective antigen (PA) protein, as described previously (Ivins, B. E., Infection and Immunity, 60:662-668, 1992; Ramirez, D. M., et al., J. Industrial Microbiol. and Biotechnol. 28:232-238, 2002 This is the anthrax protein exemplified in the Examples. The present invention is also likely to be applicable to other types of anthrax vaccines, such as AVA and DNA plasmid vaccines (e.g., Price et al., Infection and Immunity, 69:4509-4515, 2001)
A polypeptide of the invention can be a naturally occurring one or it can be produced recombinantly. (The terms polypeptide and protein are used interchangeably herein.) Preferably, a polypeptide component of the anthrax bacterium, e.g., the PA protein, is produced recombinantly. Methods to clone suitable sequences and to generate recombinant vectors in which the sequences of interest are operatively linked to suitable expression control sequences, are routine and conventional. Typical such methods (as well as molecular biology methods used in other aspects of the invention) are described in, among many other sources, Sambrook, J. et al. (1989) Molecular Cloning, a Laboratory Manual, Cold Spring Harbor Press, Cold Spring Harbor, N.Y., and Ausubel, F. M. et al. (1995). Current Protocols in Molecular Biology, NY, John Wiley & Sons. The phrase “expression control sequence” means a polynucleotide sequence that regulates expression of a polypeptide coded for by a polynucleotide to which it is functionally (“operably”) linked. Expression can be regulated at the level of the mRNA or polypeptide. Thus, the expression control sequence includes mRNA-related elements and protein-related elements. Such elements include promoters, enhancers (viral or cellular), ribosome binding sequences, transcriptional terminators, etc. An expression control sequence is operably linked to a nucleotide coding sequence when the expression control sequence is positioned in such a manner to effect or achieve expression of the coding sequence. For example, when a promoter is operably linked 5′ to a coding sequence, expression of the coding sequence is driven by the promoter. Suitable expression control sequences, such as strong constitutive or regulatable promoters, will be evident to the skilled worker.
The invention encompasses functional fragments or functional variants of wild type anthrax proteins. A “functional” fragment or variant, as used herein, includes a polypeptide that comprises any of a variety of changes (modifications), either naturally occurring or deliberately generated, provided that the polypeptide retains at least one epitope which allows it to be immunogenic. Preferably, the fragment or variant—retains the ability to elicit (induce) a protective response against anthrax infection. One of skill in the art can readily determine if a given fragment or variant exhibits the desired property, using conventional methods such as those disclosed herein. Naturally occurring allelic variants of the proteins are encompassed by the invention.
Polypeptides used in compositions or methods of the invention can be functional fragments of full-length proteins. Any desirable size (length) polypeptide can be used, ranging from one amino acid shorter than a wild type protein to a small peptide (e.g., about 8-10 amino acids long) bearing only a single epitope and/or antigenic sequence.
The polypeptides can also be functional variants. For example, variant PA polypeptides used in the methods of the invention may exhibit substantial identity to comparable portions of wild type PA. The term “substantial identity” or “substantial similarity” as used herein indicates that a polypeptide (or a nucleic acid) comprises a sequence that has at least about 90% sequence identity to a reference sequence, or preferably at least about 95%, or more preferably at least about 98% sequence identity to the reference sequence, over a comparison window of at least about 10 to about 100 or more amino acids residues or nucleotides. Methods to determine sequence identity (between nucleic acids or proteins) are conventional. Alignments can be accomplished by using any effective algorithm. For pairwise alignments of DNA sequences, the methods described by Wilbur-Lipman (e.g., Wilbur et al. (1983), Proc. Natl. Acad. Sci., 80, 726-730) or Martinez/Needleman-Wunsch (e.g., Martinez (1983), Nucleic Acid Res. 11, 4629-4634) can be used. Pairs of protein sequences can be aligned by the Lipman-Pearson method (e.g., Lipman et al. (1985), Science 227,1435-1441), e.g., with k-tuple set at 2, gap penalty set at 4, and gap length penalty set at 12. Various commercial and free sources of alignment programs are available, e.g., MegAlign by DNA Star, BLAST (National Center for Biotechnology Information), BCM (Baylor College of Medicine) Launcher, etc. Percent sequence identity can also be determined by other conventional methods, e.g., as described in Altschul et al.(1986), Bull. Math. Bio. 48, 603-616, 1986 and Henikoff et al. (1992), Proc. Natl. Acad Sci. USA 89,10915-10919.
Variant polypeptides of the invention include polypeptides having one or more naturally occurring (e.g., through natural mutation) or non-naturally-occurring (e.g., by deliberate modification, such as by site-directed mutagenesis) modifications, e.g., insertions, deletions, additions and/or substitutions, either conservative or non-conservative. By “conservative substitutions” is meant by combinations such as Gly, Ala; Val, Ile, Leu; Asp, Glu; Asn, Gln; Ser, Thr; Lys, Arg; and Phe, Tyr. Variants can include, e.g., homologs, muteins and mimetics. Many types of protein modifications, including post-translational modifications, are included. Post-translational modifications include naturally occurring or synthetically produced, covalent or aggregative conjugates with other chemical moieties, e.g., glycosyl groups, lipids, phosphates, acetyl groups, etc., as well as cleavage, such as of terminal amino acid(s). See, e.g., modifications disclosed in U.S. Pat. No. 5,935,835. The invention also encompasses variants such as polypeptides in which cysteine residues which are nonessential for biological activity are deleted or replaced with other amino acids, thereby preventing the formation of incorrect intramolecular disulfide bridges; naturally occurring variants arising from alternative mRNA splicing events; and altered forms reflecting genetic polymorphism (e.g., allelic variation). Other active variants may comprise added peptide sequences, either naturally occurring or heterologous, such as, e.g., leader, signal, secretory, targeting, enzymatic etc. sequences. Furthermore, the polypeptide can be modified by any of a variety of art-recognized modifications, such as in the variant polypeptides discussed in US2002/0052475.
Compositions and Methods for Intranasal (IN) Delivery
One aspect of the present invention relates to methods of preparing dried pharmaceutical compositions, in particulate form (e.g., in a powder), which are suitable for direct intranasal administration, and to compositions made by these methods. Such dried particles can also be reconstituted in a pharmaceutically acceptable liquid (aqueous) form prior to delivery to mucosa or to skin.
As noted above, one aspect of the invention is a method of preparing an immunogenic anthrax composition (e.g., an anthrax vaccine), comprising one or more of the following steps: atomizing a liquid formulation of an anthrax composition to produce an atomized formulation; freezing said atomized formulation to form solid particles; and drying said solid particles to produce dried particles. Preferably, said atomized formulation comprises droplets having a volume mean diameter (as defined by W. H. Finley, “The mechanics of inhaled pharmaceutical aerosols, an introduction”, Academic Press, London, UK (2001)) of between about 35 μm and about 300 μm. In a preferred embodiment, the powder comprises dried particles that have a mean aerodynamic diameter (as defined in W. H. Finley, supra) of between about 8 μm and about 140 μm. This method, and compositions made by the method, are sometimes generally referred to herein as a “spray-freeze-dry” (SFD) method or compositions.
Particles of the above pharmaceutical compositions are of an appropriate size, density and/or morphology to facilitate intranasal administration. Without wishing to be bound by any particular theory, it is proposed that, following intranasal administration, the compositions described above are delivered to mucous membranes, e.g., of the nasal lining or the sinuses, where they adhere, rather than being propelled through the sinus cavities into the pulmonary system, and that adherence to such mucous membranes allows a faster rate of absorption than with other formulations of therapeutic and prophylactic compositions. When the inventive composition is a vaccine, the time required to mount an effective antibody response is thus reduced, and mucosal immunity (e.g., mediated by an IgA response) is enhanced. Intranasal administration of such inventive vaccines elicits both systemic and naso-mucosal IgA immune responses.
As noted above, another aspect of the invention is a method of preparing an immunogenic anthrax composition (e.g., an anthrax vaccine), comprising one or more of the following steps: atomizing a liquid formulation of an anthrax composition to produce an atomized formulation; freezing said atomized formulation to form solid particles; and drying said solid particles at about atmospheric pressure, in the presence of vibration, internals, mechanical stirring, or a combination thereof, to produce dried particles (e.g. to produce a powder). By “about atmospheric pressure” is meant a pressure ranging from about one half atmosphere to about five atmospheres. By “drying” is meant removal of the volatile components of the formulation from the solid frozen particles. Preferably, the powder comprises dried particles having a volume mean diameter of between about 35 μm and about 300 μm, more preferably between about 50 μm and about 300 μm and/or the dried particles have a volume mean aerodynamic diameter of between about 8 μm and about 140 μm. Preferably, the frozen, solid particles are in a fluidized state as they are being dried. This method, and compositions made by the method, are sometimes referred to herein as “spray-freeze-atmospheric-dry” method or compositions. An advantage of compositions produced by this method is that they do not agglomerate.
A further discussion of “spray-freeze-dried” and “spray-freeze-atmosphere-dried” methods and compositions can be found in U.S. patent application Ser. Nos. 10/299,012 and 10/299,010.
Additional advantages of the compositions of the invention are that the compositions are readily aerosolized, offer good stability, sterility, emitted dose and preservation of bioactivity, leave little residue in a delivery device such as an inhalation device, and are readily reconstituted in liquid. The particles may exhibit a low tap density, which facilitates the aerosolization of the particles, e.g., for respiratory delivery. The particles exhibit low levels of fines, which renders them easy to handle. The methods of the invention allow for a well-controlled distribution of particle sizes. Therefore, the inventive compositions comprise a well-controlled distribution of particle sizes. The morphology of the particles reduces the potential for their agglomerization and further facilitates aerosolization. The compositions are stable in the absence of refrigeration, allowing for more convenient and less expensive storage and transportation than, e.g., liquid formulations. Compositions of the invention are particularly well suited for mass vaccinations. In one embodiment of the invention, inventive compositions are administered by respiratory (e.g., intranasal) administration. Compositions of the invention are particularly well suited to intranasal administration, since the well controlled particle size distribution allows accurate targeting of the nasal mucosa. Advantages of respiratory administration compared to administration by injection (e.g., intradermal or sub-dermal) include increased patient compliance and enhanced immune responses. Respiratory administration is also advantageous in that it is a non-invasive procedure, which is painless and easy to perform.
An immunogenic composition of the invention can be initially formulated as a liquid formulation, using any of a variety of conventional liquids. Preferably, the liquid is an aqueous one, such as, e.g., water (e.g., injectable grade water) or any of a variety of conventional buffers, which may or may not contain additional salts. The pH of the buffer will generally be chosen to stabilize the protein, and will be ascertainable by those in the art. Generally, this will be in the range of physiological pH. Thus, preferred pH ranges of the initial liquid formulation are from about 1 to about 10, with from about 3 to about 8 being particularly preferred, and from about 5 to about 7 being especially preferred. As will be appreciated by those in the art, there are a large number of suitable buffers that may be used. Suitable buffers include, but are not limited to, sodium acetate, sodium citrate, sodium succinate, ammonium bicarbonate and carbonate. Generally, buffers are used at molarities from about 1 mM to about 2 M, with from about 2 mM to about 1 M being preferred, and from about 10 mM to about 0.5 M being especially preferred, and 50 to 200 mM being particularly preferred. Generally, salts, if present in the liquid solution, are used at molarities from about 1 mM to about 2 M, with from about 2 mM to about 1 M being preferred, and from about 10 mM to about 0.5 M being especially preferred, and 50 to 200 mM being particularly preferred. Suitable salts include, but are not limited to, NaCl.
The liquid formulation can be in any of a variety of forms, e.g., a solution, a suspension, a slurry or a colloid. Optionally, the liquid formulation can comprise one or more conventional pharmaceutically acceptable excipients. “Excipients” generally refer to compounds or materials that are added to enhance the efficacy of a formulation of an active pharmaceutical ingredient (API). Examples include, e.g., cryoprotectants and lyoprotectants, which are added to ensure or increase the stability of the protein during the spray-freeze dry process or spray-freeze atmosphere dry process, and afterwards, for long term stability and flowability of the powder product. Suitable protectants are generally relatively free flowing particulate solids, do not thicken or polymerize upon contact with water, are essentially innocuous when inhaled by a patient or otherwise introduced into a patient, and do not significantly interact with the therapeutic agent in a manner that alters its biological activity. Suitable excipients include, but are not limited to, proteins such as human and bovine serum albumin, gelatin, immunoglobulins, carbohydrates including monosaccharides (galactose, D-mannose, sorbose, etc.), disaccharides (lactose, trehalose, sucrose, etc.), cyclodextrins, and polysaccharides (raffinose, maltodextrins, dextrans, etc.); an amino acid such as monosodium glutamate, glycine, alanine, arginine or histidine, as well as hydrophobic amino acids (tryptophan, tyrosine, leucine, phenylalanine, etc.); a methylamine such as betaine; an excipient salt such as magnesium sulfate; a polyol such as trihydric or higher sugar alcohols, e.g. glycerin, erythritol, glycerol, arabitol, xylitol, sorbitol, and mannitol; propylene glycol; polyethylene glycol; Pluronics; surfactants; and combinations thereof. Preferred excipients include e.g, trehalose, sucrose and mannitol. Another class of excipient, mucoadhesives, are often used to increase contact of an API with mucosal surfaces. Examples of mucoadhesives include, e.g., chitosan, dermatan sulfate, chondroitin, and pectin. Additionally, conventional cosolvents, which improve the solubility of APIs, can be added to liquid formulations suitable for the SFD processes disclosed herein.
Generally, when mucoadhesives are used, they are used in amounts ranging from about 1 to 95 wt %, with from about 1 to 50 wt % preferred, from about 5 to 50 wt % being especially preferred, and from about 5 to 20% being particularly preferred. In general, cryoprotectants are used at a concentration of between about 5 wt % and about 95 wt %.
In one embodiment, the dried powders of the invention are later combined with bulking agents or carriers, which are used to reduce the concentration of the therapeutic agent in the powder being delivered to a patient; that is, it may be desirable to have larger volumes of material per unit dose. Bulking agents may also be used to improve the dispersibility of the powder within a dispersion device, and/or to improve the handling characteristics of the powder. This is distinguishable from the use of bulking agents or carriers during the spray-drying process. Suitable bulking agents are generally crystalline (to avoid water absorption) and include, but are not limited to, lactose and mannitol. Accordingly, bulking agents such as lactose, if added, may be added in varying ratios, with from about 99:1 of a therapeutic agent of interest to bulking agent to about 1:99 being preferred, and from about 1:5 to about 5:1 being more preferred, and from about 1:10 to about 1:20 being especially preferred.
Liquid formulations of the invention can be atomized by any of a variety of conventional procedures. For example, the liquid can be sprayed through a two-fluid nozzle, a pressure nozzle, or a spinning disc, or atomized with an ultrasonic nebulizer or a vibrating orifice aerosol generator (VOAG). In one embodiment, a liquid formulation is atomized with a pressure nozzle such as a BD AccuSpray™ nozzle.
In a preferred embodiment, atomization conditions are optimized such that the mean mass diameter of the atomized droplets (e.g., nebulized droplets) is at least about 20μ, preferably between about 35 μm and about 300 μm, more preferably between about 50 μm and about 300 μm, still more preferably between about 50 μm and about 100 μm. Methods to optimize the generation of droplets of the desired size are conventional. Among the conditions that can be varied are atomization gas flow, atomization gas pressure, liquid flow rate, etc. Also, the type and size of the nozzle can be varied. Liquid drop size can be readily measured, using conventional techniques, such as laser diffraction. The size of dried particles can be measured by conventional techniques, such as, e.g., scanning electron microscopy (SEM) or laser diffraction.
In one embodiment, in which frozen, atomized particles are dried at about atmospheric pressure, as is discussed elsewhere herein, the size of the atomized droplets can be, e.g., at least about 20 μm, preferably between about 20 μm and about 300 μm, more preferably between about 35 μm and about 100 μm or between about 50 μm and about 100 μm.
Following the atomization of a liquid formulation, the droplets are rapidly frozen to form solid particles. Preferably, the droplets are frozen immediately, or substantially immediately, after the atomization step.
In one embodiment, the droplets are frozen by immersing them in a cold liquid that is below the freezing point of the liquid formulation from which the atomized droplets were formed. In a preferred embodiment, the temperature of the cold liquid is about −200° C. to −80° C., more preferably between about −200° C. to −100° C., most preferably about −200° C. (liquid nitrogen is about −196° C.). Any suitable cold liquid may be used, including liquid nitrogen, argon and hydrofluoroethers, or a compressed liquid, such as compressed fluid CO2, helium, propane or ethane, or equivalent inert liquids, as is well known in the art. For example, in one embodiment, a liquid preparation of an anthrax composition is atomized through a spray nozzle that is positioned above a vessel containing a suitable cold liquid, such as, e.g., liquid nitrogen. The droplets freeze instantaneously upon contact with the cold liquid.
In another embodiment, the droplets are frozen by passage through a gas (e.g., cold air, nitrogen, helium or argon), in a cooling chamber, wherein the gas is below the freezing point of the droplets. In a preferred embodiment, the cold gas is about −5° C. to −60° C., more preferably between about −20° C. to −40° C. The gas can be cooled by conventional methods, such as by cooling coils, heat exchangers or chiller condensers. The temperature of the gas can be reduced with conventional procedures, e.g., with liquid nitrogen, solid carbon dioxide or an equivalent cryogenic agent to produce the subfreezing temperatures.
Following the formation of solid frozen particles, the particles are dried to produce a powder. By “dry” is meant having a negligible amount of liquid, e.g., having a moisture content such that the particles are readily dispersible to form an aerosol, e.g. in an inhalation device. This moisture content is generally below about 15% by weight water, with less than about 10% being preferred and less than about 1% to about 5% being particularly preferred.
In one embodiment of the invention, the frozen droplets are dried by lyophilization (freeze-drying, under vacuum), using a conventional lyophilization apparatus. This method is generally called a “spray-freeze-dry” or SFD method, and compositions made by the method are called “spray-freeze-dry” or SFD compositions. For example, in one embodiment, when particles have been frozen by spraying them into a vessel (such as a Virtis freeze-drying flask) containing liquid nitrogen, the vessel can then be attached to a conventional lyophilizer and the excess liquid nitrogen evaporated off. The frozen aerosol is typically dried within about 48 hours and reaches a moisture level below about 1 wt %. Alternatively, droplets that have been frozen in cold air at about atmospheric pressure and, optionally, partially dried at about atmospheric pressure (as is discussed below) can then be placed in a lyophilization flask and subjected to lyophilization.
In another embodiment, the frozen droplets are dried by sublimation in a cold, desiccated gas (e.g., air, nitrogen or helium) stream at about atmospheric pressure. By “about atmospheric pressure” is meant herein a pressure ranging from about one half atmosphere to about five atmospheres. The temperature of the gas can be reduced by any of a variety of conventional procedures, e.g., with liquid nitrogen, solid carbon dioxide or an equivalent cryogenic agent. Particles of the invention that are dried in such a manner are sometimes referred to herein as “spray-freeze-atmosphere-dried” particles. In a preferred embodiment, atomized droplets are frozen and dried in the same “spray-freeze-atmosphere-dry” chamber, allowing the freezing and drying procedures to be carried out in a single step.
One apparatus and method for drying solid, frozen particles in cold air at about atmospheric pressure is disclosed in Leuenberger, U.S. Pat. No. 4,608,764. See also Examples in U.S. patent application Ser. Nos. 10/299,012 and 10/299,010. Other types of conventional apparatus can also be used, as will be appreciated by persons of skill in the art.
In a preferred embodiment, frozen atomized particles are dried in a cold gas at about atmospheric pressure in the presence of conditions that enhance fluidization of the particles. In a most preferred embodiment, the frozen, atomized particles are dried in the presence of vibration, internals, mechanical stirring, or combinations thereof, during the drying process. The term, “internals,” as used herein, refers to any physical barrier inside a chamber (e.g., the SFD chamber) or fluidized bed, such as, e.g., blades, plates or other barriers. Such treatments allow the particles to achieve a fluidized state, and help to prevent channeling.
In another embodiment, the frozen droplets are dried by a combination of sublimation in a cold, desiccated gas (e.g., air) stream at about atmospheric pressure, as described above, and lyophilization. For example, a composition that has been partially dried at about atmospheric pressure (e.g., to form a cake or a powder that still contains undesirable amounts of liquid) is removed to a lyophilizer, in which the composition is dried further.
Conventional methods can be used to collect the dried compositions. In one embodiment, the dried particles are collected on a filter, from which they can be removed for use in, e.g., medical applications. In another embodiment, the spray-freeze atmosphere dried particles are collected in a product vessel. Partially dried particles may form a loose cake, from which remaining moisture can be removed by further atmospheric sublimation in a cold desiccated air stream, or they can optionally be removed to a lyophilizer or other suitable device and further dried under reduced pressure (below atmospheric pressure.)
Particles dried by any of the above methods exhibit substantially the same properties (e.g., particle size, porosity, and the like).
Following the drying procedure, a composition of the invention can achieve the form of a free-flowing powder. The dry, porous particles of the composition are roughly the same size (geometric diameter) and shape as the frozen droplets prior to drying.
Dried particles of the invention exhibit desirable aerodynamic properties show a desirable morphology (as shown by SEM) and a desirable density. Furthermore, the particles exhibit lower amounts of residual powder remaining in a delivery device following its use, exhibit greater stability than, e.g., liquid insulin formulations, and are readily reconstituted in liquid.
One aspect of the invention is a method of treating a patient in need thereof, comprising administering to the patient an effective amount of an immunogenic anthrax composition (e.g., an anthrax vaccine) produced by a method of the invention. By an “effective amount” is meant herein an amount that is effective to elicit a desired response. For example, an effective amount of an immunogenic composition is an amount that is effective to elicit a detectable immune response. An effective dose can be determined empirically, according to conventional procedures, taking into account well known factors such as the age, weight, and/or clinical condition of the patient, the method of and scheduling of administration, and the like. As for other methods disclosed herein, the patient can be any animal, preferably a mammal such as, e.g., a farm or other domestic animal, or a rat, mouse, hamster, guinea pig, rabbit, etc., preferably a human.
Compositions of the invention can be administered by any of a variety of routes that are known to the skilled worker, including respiratory preferably intranasal, routes. In one embodiment, the composition is administered to a mucosal tissue, such as a mucosal tissue of the nasal passages and the sinuses. In a preferred embodiment, a composition of the invention is administered to a patient in need thereof via the respiratory system. By “administration through the respiratory system” or “respiratory administration” is meant herein that an agent is administered to the nose (intranasally), or the lungs (pulmonary administration).
Conventional methods of administration may be used. Suitable applicators (e.g., inhalers) are known in the art. Typical delivery devices include, but are not limited to, the devices disclosed in U.S. patent application Ser. No. 09/879,714 (filed Jun. 12, 2001) and 09/758,776 (filed Jan. 12, 2001). In a preferred embodiment, the device used for nasal administration is a “Solovent” apparatus. Dosages to be administered can be determined by conventional procedures known to those of skill in the art. See, e.g., The Pharmacological Basis of Therapeutics, Goodman and Gilman, eds., Macmillan Publishing Co., New York. Factors to be considered include the activity of the specific agent involved, the metabolic stability and length of action of the agent, mode and time of administration, drug combination, rate of excretion, the species being treated, and the age, body weight, general health, sex, diet and severity of the particular disease states of the host undergoing therapy. Dosages for eliciting an effective immune response (e.g., dosages for effective vaccination) are well known to those of skill in the art.
The invention also includes a unit dosage receptacle or dry powder inhaler, comprising an effective amount of an immunogenic anthrax composition (e.g., an anthrax vaccine) of the invention.
Compositions of the invention can achieve greater therapeutic effects following intranasal administration than do liquid formulations. See, e.g., Example 11. Therefore, the invention includes a method of reducing the amount of an immunogenic anthrax composition (e.g., an anthrax vaccine) that is required to produce an efficacious result following intranasal administration to a patient in need thereof, comprising administering to said patient, intranasally, an effective amount of an immunogenic anthrax composition of the invention.
The invention further includes a method to elicit (induce) an immune response in a patient, comprising administering to the patient an effective amount of an immunogenic anthrax composition (e.g., an anthrax vaccine) of the invention. The term “immune response” as used herein encompasses, for example, mechanisms by which a multi-cellular organism produces antibodies against an antigenic material that invades the cells of the organism or the extra-cellular fluid of the organism. The antibody so produced may belong to any of the immunological classes, such as immunoglobulins A, D, E, G or M. Other types of responses, for example cellular immunity, such as the induction of cytotoxic T cells, are also included. Immune response to antigens is well studied and widely reported. A survey of immunology is given, e.g., in Roitt I., (1994). Essential Immunology, Blackwell Scientific Publications, London. Methods in immunology are routine and conventional (see, e.g., Currents Protocols in Immunology; edited by John E. Coligan et al., John Wiley & Sons, Inc.).
In one aspect, the invention relates to an anthrax vaccine (a vaccine used to stimulate the immune system of a living organism so that protection against future infection by anthrax is provided). That is, the vaccine can result in the amelioration of at least some of the symptoms engendered by infection with anthrax. The delivery platforms and methods described herein would also be applicable to gene therapy methods of introducing nucleic acids encoding the anthrax PA.
Inhalation anthrax enters the body and exerts its pathophysiologic effects through nasal mucous membranes. Protection against infection can be provided at the first site of entry by neutralizing infectious agents with locally produced mucosal IgA. Although systemic immune responses are readily elicited by traditional immunization routes (such as IM, ID, etc.), mucosal responses are more difficult to achieve in general. An advantage of intranasal (IN) delivery of dry powder vaccine is its ability to elicit both systemic and mucosal immune response. In addition, IN powder vaccine delivery may reduce the required dose because of the effectiveness of mucosal powder drug intake.
Intradermal (ID) Delivery Methods, Using Hollow Microneedles (HMN) or Solid Microneedles (SMN)
In one aspect, the present invention utilizes “microneedles”, both “hollow” and “solid,” to administer an anthrax rPA vaccine to skin. According to the present invention, “hollow” microneedles are small microprojections that enable reproducible intra-dermal (ID) delivery. Devices comprised of such microneedle structures and suitable fluid-driving mechanisms are known in the art. Suitable “hollow” microneedle structures and fluid-driving mechanisms are described in detail in U.S. applications Ser. No. 10/028,988, filed Dec. 28, 2001 and 10/185,717, filed Jul. 1, 2002, and PCT publication No. WO 02/02179 A1, which are incorporated herein by reference.
Delivery with hollow microneedles (HMN) allows delivery into an intradermal space within mammalian skin. An immunogenic anthrax composition can be administered, e.g., through a small gauge hollow needle having an outlet with an exposed height between 0 and 1 mm, said outlet being inserted into the skin to a depth of between 0.3 mm and 2 mm, such that delivery of the substance occurs at a depth between 0.3 mm and 2 mm. It has been found that using the method of the invention, the effective amount is less than that required to be administered by intramuscular injection to achieve an immunogenic effect, such as protective immunity.
One benefit of the invention is that ID administration with enhanced immunogenicity allows equivalent biological effects while using less of an immunogenic composition. This results in direct economic benefit to the manufacturer and perhaps consumer, especially for expensive vaccine preparations. Likewise, higher immunogenicity allows reduced overall dosing and decreases patient side effects associated with higher dosing.
Anatomically, the outer surface of the body is made up of two major tissue layers, an outer epidermis and an underlying dermis, which together constitute the skin (for review, see Physiology, Biochemistry, and Molecular Biology of the Skin, Second Edition, L. A. Goldsmith, Ed., Oxford University Press, New York, 1991). The epidermis is subdivided into five layers or strata of a total thickness of between 75 and 150 μm. Beneath the epidermis lies the dermis, which contains two layers, an outermost portion referred to at the papillary dermis and a deeper layer referred to as the reticular dermis. The papillary dermis contains vast microcirculatory blood and lymphatic plexuses. In contrast, the reticular dermis is relatively acellular and avascular and made up of dense collagenous and elastic connective tissue. Beneath the epidermis and dermis is the subcutaneous tissue, also referred to as the hypodermis, which is composed of connective tissue and fatty tissue. Muscle tissue lies beneath the subcutaneous tissue.
It is appreciated by those of skill in the art that skin thickness varies, both among individuals, and in any individual between different locations on the body. Thus, depending on the location of administration, the depth of delivery needed to target the ID space will vary.
The subject of intradermal delivery of the present invention is a mammal, preferably, a human. The biologically active reagent, with or without a tracer reagent, may be delivered into the intradermal space by a needle or cannula, usually from about 300 μm to about 5 mm long. Preferably, the needle or cannula is about 300 μm to about 1 mm long, with the outlet inserted into the skin of the subject to a depth of 1 mm to 3 mm. Preferably, a small gauge needle or cannula, between 30 and 36 gauge, preferably 31-34 gauge is used. The outlet of the needle or cannula is preferably inserted to a depth of 0.3 mm (300 μm) to 1.5 mm.
The immunogenic anthrax composition may be infused, or preferably, administered as a bolus. As used herein, the term “bolus” is intended to mean an amount that is delivered within a time period of less than ten (10) minutes. “Infuision” is intended to mean the delivery of a substance over a time period greater than ten (10) minutes It is understood that bolus administration or delivery can be carried out with rate controlling means, for example a pump, or have no specific rate controlling means, for example user self-injection.
In one preferred embodiment, an immunogenic anthrax composition is administered through at least one small gauge hollow needle having an outlet with an exposed height between 0 and 1 mm, said outlet being inserted into the skin to a depth of between 0.3 mm and 2 mm, such that delivery of the composition occurs at a depth between 0.3 mm and 2 mm.
As used herein, “intradermal delivery” means the delivery of materials to the intradermal space and its interrogation as described by Pettis et al. in WO 02/02179 A1 (PCT/US01/20782 having a priority date of Jun. 29, 2000).
In a particularly preferred embodiment the immunogenic composition is delivered though a device that allows skilled and unskilled medical staff to reach the dermal space with each attempt. Micro-cannula- and microneedle-based methodology and devices are described in U.S. Application Ser. No. 606,909, filed Jun. 29, 2000. Standard steel cannula can also be used for intra-dermal delivery using devices and methods as described in U.S. Ser. No. 417,671, filed Oct. 14, 1999. These methods and devices include the delivery of substances through narrow gauge (30 G or narrower) “micro-cannula” with a limited depth of penetration (typically ranging from 10 μm to 2 mm), as defined by the total length of the cannula or the total length of the cannula that is exposed beyond a depth-limiting hub feature. In one preferred embodiment, the microneedle is configured in a delivery device which positions the microneedle perpendicular to skin surface.
As used herein, “conventional delivery” means any method for delivering any material that has, or is thought to induce immune responses that are similar in magnitude or weaker than via intramuscular delivery. Conventional delivery may include subcutaneous, iontophoretic, and intradermal delivery methods such as those described in U.S. Pat. No. 5,800,420 to Gross.
According to the present invention, “solid” microneedles (SMN) are small microprojections that are used to abrade the stratum comeum to allow the vaccine to access the epidermal tissue. The microprojections are part of an “abrading surface” that, together with a suitable base and handle, make up a “microenhancer” or “microabrader” device. These devices are typically used in association with topical vaccine delivery to the skin. Preferably, the device used in the present invention penetrates, but does not pierce, the stratum corneum. The substance to be administered using the methods of this invention may be applied to the skin prior to abrading, simultaneous with abrading, or post-abrading. Devices comprised of a suitable abrading surface, base and handle are referred to herein as SMN devices. Suitable such devices are known in the art and are described for example in U.S. application Ser. Nos. 09/405,488, filed Sep. 24, 1999; 09/576,643, filed May 22, 2000; 09/974,829, filed Oct. 12, 2001; and 10/282,231, filed Oct. 29, 2002.
The SMN method for delivering a vaccine or other substance includes the steps of coating a patient's outer skin layer or a microabrader 2, see
As shown in
Microabrader 2 is applied to a subject by moving microabrader 2 across the subject's skin with enough pressure to enable abrading surface 5 to open the outer protective skin or stratum corneum of the subject. The inward pressure applied to the base causes microabrader 2 to be pressed into the subject's skin. Accordingly, it is preferable that the height of the sloping mushroom-like crown 4b be sufficient to prevent the applied substance from flowing over and onto the facet 4c when microabrader 2 is being used. As will be described below, abrading surface 5 comprises an array of microprotrusions.
A handle 6 is attached to base 4 or may be integral with base 4. As shown in
As shown in the cross-section of
Abrading surface 5 is designed so that when microabrader 2 is moved across a patient's skin, the resultant abrasions penetrate the stratum corneum. Abrading surface 5 may be coated with a medicament or substance desired to be delivered to the patient's viable epidermis.
In order to achieve the desired abrasions, the microabrader 2 should be moved across a patient's skin at least once. The patient's skin may be abraded in alternating directions. The structural design of the microabrader according to the invention enables the medicament or substance to be absorbed more effectively thereby allowing less of the medicament or substance to be applied to a patient's skin or coating abrading surface 5.
Abrading surface 5 may be coated with a substance desired to be delivered to the patient. In one embodiment, the substance may be a powder disposed on abrading surface 5. In another embodiment, the substance to be delivered may be applied directly to the patient's skin prior to the application and movement of microabrader 2 on the patient's skin.
Referring to
As shown in
The microprotrusions 14 preferably terminate at blunt tips 18. Generally, the tip 18 is substantially flat and parallel to the support 14. When the tips are flat, the total length of the microprotrusions do not penetrate the skin; thus, the length of the microprotrusions is greater than the total depth to which said microprotrusions penetrate said skin. The tip 18 preferably forms a well defined, sharp edge 20 where it meets the sides 16. The edge 20 extends substantially parallel to the abrading surface support 12 and defines a further scraping edge. In further embodiments, the edge 20 can be slightly rounded to form a smooth transition from the sides 16 to the tip 18. Preferably, the microprotrusions are frustoconical or frustopyramidal in shape.
The microabrader device 10 and the microprotrusions can be made from a plastic material that is non-reactive with the substance being administered. A non-inclusive list of suitable plastic materials include, for example, polyethylene, polypropylene, polyamides, polystyrenes, polyesters, and polycarbonates as known in the art. Alternatively, the microprotrusions can be made from a metal such as stainless steel, tungsten steel, alloys of nickel, molybdenum, chromium, cobalt, titanium, and alloys thereof, or other materials such as silicon, ceramics and glass polymers. Metal microprotrusions can be manufactured using various techniques similar to photolithographic etching of a silicon wafer or micromachining using a diamond tipped mill as known in the art. The microprotrusions can also be manufactured by photolithographic etching of a silicon wafer using standard techniques as are known in the art. They can also be manufactured in plastic via an injection molding process, as described for example in U.S. application Ser. No. 10/193,317, filed Jul. 12, 2002, which is hereby incorporated by reference.
The length and thickness of the microprotrusions are selected based on the particular substance being administered and the thickness of the stratum corneum in the location where the device is to be applied. Preferably, the microprotrusions penetrate the stratum corneum substantially without piercing or passing through the stratum corneum. The microprotrusions can have a length up to about 500 microns. Suitable microprotrusions have a length of about 50 to 500 microns. Preferably, the microprotrusions have a length of about 50 to about 300 microns, and more preferably in the range of about 150 to 250 microns, with 180 to 220 microns most preferred. The microprotrusions in the illustrated embodiment have a generally pyramidal shape and are perpendicular to the plane of the device. These shapes have particular advantages in insuring that abrasion occurs to the desired depth. In preferred embodiments, the microprotrusions are solid members. In alternative embodiments, the microprotrusions can be hollow.
As shown in
The flat upper surface of the frustoconical or frustopyramidal microprotrusions is generally 10 to 100, preferably 30-70, and most preferably 35-50 microns in width.
The method of preparing a delivery site on the skin places the microabrader against the skin 28 of the patient in the desired location. The microabrader is gently pressed against the skin and then moved over or across the skin. The length of the stroke of the microabrader can vary depending on the desired size of the delivery site, defined by the delivery area desired. The dimensions of the delivery site are selected to accomplish the intended result and can vary depending on the substance, and the form of the substance, being delivered. For example, the delivery site can cover a large area for treating a rash or a skin disease. Generally, the microabrader is moved about 2 to 15 centimeters (cm). In some embodiments of the invention, the microabrader is moved to produce an abraded site having a surface area of about 4 cm2 to about 300 cm2.
The microabrader is then lifted from the skin to expose the abraded area and a suitable delivery device, patch or topical formulation may be applied to the abraded area. Alternatively, the substance to be administered may be applied to the surface of the skin either before, or simultaneously with abrasion.
The extent of the abrasion of the stratum corneum is dependent on the pressure applied during movement and the number of repetitions with the microabrader. In one embodiment, the microabrader is lifted from the skin after making the first pass and placed back onto the starting position in substantially the same place and position. The microabrader is then moved a second time in the same direction and for the same distance. In another embodiment, the microabrader is moved repetitively across the same site in alternating direction without being lifted from the skin after making the first pass. Generally, two or more passes are made with the microabrader.
Methods of formulating anthrax compositions for delivery by the microneedle-mediated methods described herein are conventional. For example, a skilled worker will recognize how to use or modify in an appropriate manner methods described herein with respect to intranasal delivery.
To examine the utility of the delivery methods of the invention for the administration of biodefense vaccines, studies were carried out in animal models. The Examples below illustrate delivery with hollow and solid microneedle devices, and with intranasal administration. Examples 1-5 illustrate studies with a mouse animal model, comparing delivery with hollow and solid microneedle devices to other methods of delivery. Examples 6-11 illustrate studies of lethal challenge with a rabbit model. These Example clearly show that intranasal (IN) and intradermal (ID) delivery methods provide superior protection compared to conventional delivery methods, such as intramascular (IM) injection. Furthermore, the abrader/topical administration method of the invention provides superior protection compared to convention methods of topical delivery.
In the foregoing and in the following examples, all temperatures are set forth uncorrected in degrees Celsius; and, unless otherwise indicated, all parts and percentages are by weight.
I. Studies in a Mouse Model
Formulations: Liquid formulations only
Adjuvants: see Experimental Groups below
Immunization Schedule: Mice were immunized at d0, d21 and d42
Antigen Dose: 10 μg rPA per mouse per immunization
Number of animals: Total=10/group
Sample Collection: Blood was collected on day 0 (“d0”, pre-bleed), d21 (prior to immunization 2), d42 (prior to immunization 3), and d56. Bronchial-alveolar lavage (BAL) fluid was collected from at least 5 animals per group at d56.
Challenge: None
Assays: Serum from individual mice was analyzed for rPA-specific total Ig by ELISA, using standard methods of the art. In addition, pooled group sera was analyzed for rPA-specific Ig isotype profiles (IgG1, IgG2aIgG2b, IgG3, IgM, IgA) using a sub-isotyping kit assay (Quantitative ELISA Immunoassay, Bethyl Laboratories, Montgomery, Tex.). BAL fluid from individual mice was analyzed for rPA-specific total Ig and IgA. Anthrax neutralization was measured by adding dilutions of sera from vaccinated or control animals to monocyte cell cultures incubated with lytic concentrations of PA and lethal toxin (LT) from B. anthracis. This assay represents an in vitro correlate of protection against anthrax disease. Cell viability was determined by measuring intracellular ATP.
Experimental Groups:
A recently developed candidate anthrax vaccine is based on a recombinantly produced Protective Antigen (rPA) (Ivins, B. E., Infection and Immunity, 60:662-668, 1992; Ramirez, D. M., et al., J. Industrial Microbiol. and Biotechnol. 28:232-238, 2002). This vaccine is being investigated by USAMRIID as an alternative to AVA due to the potential for improved efficacy and thus a reduction in the required number of booster administrations, as well as an improved safety profile. Additional pre-clinical and clinical studies are required in order to determine the most effective delivery routes for protection and to further elucidate the potential requirements for adjuvants. This vaccine was used in the examples set forth below.
For HMN studies, a hollow 1 mm 34 gauge stainless steel needle was attached to a short section of catheter tubing, which was in turn attached to a syringe. Injections into the mice were inserted essentially parallel to the skin surface in a Mantoux-style injection.
For SMN studies, the device comprised a plastic abrading surface on a hand held applicator, as shown in
At each application site, a total of six passes was made over the shaved skin of the mouse so that an area of approximately 1.5 cm2 was abraded. For some SMN experiments, the skin was abraded and the vaccine applied (“pre”), for others the vaccine was applied and the skin immediately abraded through the droplet (“abr”).
A volume of 50 μl was split between two injection or abrasion sites for all experiments, unless indicated otherwise.
IM injection was performed in a standard manner at one site using a standard 30 gauge needle. Intranasal administration was performed by liquid instillation of 30 μl (15 μl per each nostril) using a conventional Gilson pipettor (Gilson, Middleton, Wis.) For topical administration, the vaccine was applied to shaved skin.
Table 1 below displays the anthrax rPA-specific serum antibody titers (1/serum dilution) for individual mice (n=10 per group) at d21 post-immunization; i.e., following a single dose of vaccine. Sero-positive responses are indicated in bold.
The results indicate that the strongest serum antibody titers and highest overall response rates were observed following HMN-based ID delivery. Current anthrax vaccines contain alum as adjuvant and are administered either IM or SC. There was only a 20% response rate in the IM-alum group (Group 1), as compared to a 60% response rate in animals immunized ID in the absence of adjuvant (Group 4). The response rates in the ID groups were further enhanced by the addition of either alum (80%; Group 5) or CpG (90%; Group 6) as adjuvant.
SMN-based delivery stimulated an antibody response of similar magnitude and response rate (up to 30%; Groups 8 and 9) as that induced by the conventional IM-alum regimen. In addition, the SMN devices enabled topical delivery, as only a single positive responder was evident across all 30 mice receiving rPA topically without a micro-abrasion device (Groups 13-15).
IN delivery did not result in a positive antibody response after a single dose of vaccine.
Altogether, the results indicate that, relative to the conventional IM-alum vaccine regimen, HMN-based ID delivery of anthrax rPA overcomes the need for adjuvants, and increases the serum antibody response level and response rate. In addition, the results indicate that SMN-based topical administration to the skin induces an antibody response that is at least as strong as that induced by the conventional IM-alum regimen.
Tables 2 and 3, below, illustrate the anthrax rPA-specific serum antibody titers (1/serum dilution) following 2 and 3 doses of vaccine, respectively. Anesthesia-related deaths not related to any particular method of delivery or adjuvant occurred in some animals and are indicated in the Tables below.
The results presented in Tables 2 and 3 demonstrate that there is a significant booster effect upon administration of the 2nd and 3rd dose of rPA vaccine in all groups. At the completion of the study (d56), the strongest overall mean serum antibody titers were observed in the ID-HMN groups (Group 4 mean titer=78,280; Group 5 mean titer=204,800; Group 6 mean titer=138,280). In all cases the mean ID-induced titers were stronger than the corresponding titer achieved via the conventional regimen of IM injection of rPA plus alum (Group 1 mean titer =54,400). Thus, as indicated above, HMN-based ID delivery induces a stronger serum antibody response than via the conventional regimen of IM-alum and reduces or eliminates the need for adjuvants.
In addition, the results indicate that SMN induces antibody responses that are of comparable or greater magnitude than those induced via the conventional regimen of IM-alum. At d56, mean SMN-induced titers ranged from 30,720 (Group 7) to 71,680 (Group 9), as compared to a mean titer of 54,400 in the IM-alum group (Group 1). Thus, SMN delivery also reduces or eliminates the need for adjuvants and, in the presence of adjuvants, induces an immune response that is at least as strong as that induced by IM injection, yet without a conventional needle-based injection.
In addition, the results indicate that IN delivery of anthrax rPA requires use of an adjuvant, in this case CpG, to induce a significant immune response and 100% sero-conversion. Upon addition of adjuvant, however, an antibody response of similar but slightly lower magnitude than via IM injection is achieved (Group 3 mean titer at d56=36,480), yet without a conventional needle-based injection.
To further characterize the immune response, d56 sera from the experimental groups presented in Example 1 above were further investigated for Ig isotype profile. Different isotypes are involved in different immune functions; e.g., IgG fixes complement and binds to Fc-receptors, IgE is involved in allergic responses, IgA is involved in mucosal immune responses. Helper T (Th) cells can be divided into 2 subsets, based on the particular cytokines produced; “Th1” cells produce the pro-inflammatory cytokines IFN-γ and TNF-α important in cellular immune responses, whereas “Th2” cells produce IL-4, IL-5 and IL-10 which are important for humoral immune responses. Both Th1 and Th2 cytokines influence IgG isotype switching; “Th1” cytokines favor production of IgG2a, whereas “Th2” cytokines favor production of IgG1. Thus, the ratio of IgG1:IgG2a is suggestive of the type of helper T cell response induced by a given vaccine.
The results presented in
Table 4, below, displays the IgG1:IgG2a ratios for the experimental groups presented in Example 1. In groups receiving rPA either without adjuvant or with alum as adjuvant, IgG responses displayed a higher IgG1:IgG2a ratio than the corresponding groups immunized with rPA plus CpG. Altogether, the novel methods and devices described herein appeared to induce IgG1:IgG2a ratios as expected for these types of adjuvants. However, the IgG1:IgG2a ratios in the IN groups were, in general, lower than those present in other groups, suggesting more Th1 activity following IN delivery than that achieved via the other routes.
Antrax-specific antibodies present in the BAL provide a first line of defense against the inhalation form of the disease. At the termination of the experiment described in Example 1, BAL samples were collected from 5-10 mice per group and analyzed for PA-specific antibodies by ELISA. PA-specific antibody titers (1/BAL dilution) are presented in Table 5, below:
The results presented in Table 5 indicate that HMN- and SMN-based delivery of anthrax rPA vaccine induce significant levels of PA-specific antibodies in the BAL fluid. As with the serum titers, HMN-based delivery resulted in the strongest overall titers in the BAL with individual mice responding with a mean group titer as high as 115 (Group 5), as compared to a mean group titer of 51 following IM injection (Group 1). Notably, animals immunized via HMN raised a significant titer in the BAL even in the absence of added adjuvant. Likewsie, SMN-based delivery resulted in the induction of significant titers in the BAL fluid even in the absence of added adjuvant. In addition, SMN-induced titers were comparable in magnitude to those generated by the conventional IM-alum regimen. Thus, the methods and devices of the present invention are able to overcome the requirements for adjuvants in the induction of immune responses in the BAL fluid. Such immune responses in the BAL are likely to be important for protection against aerosol challenge with anthrax spores.
IN delivery required an adjuvant in order to induce significant antibody titers in the BAL fluid. In the presence of adjuvant, however, rPA administered IN yielded similar but slightly lower BAL titers as compared to IM injection.
In addition to the total Ig analysis presented above, BAL fluid was also analyzed for PA-specific IgA. IgA is a secretory antibody involved in protection from infection at mucosal surfaces. PA-specific IgA was only detectable in a limited number of samples; 4/9 samples from the IN/CpG group (Group 3) and 1/5 samples from the ID/CpG group (Group 6) were positive at dilutions ranging from 1:2 to 1:8. All other samples were negative. These results indicate that IN and ID delivery are unique among the routes tested in their ability to induce IgA responses in the BAL fluid.
Anthrax neutralization was measured by adding dilutions of sera from vaccinated or control animals to monocyte cell cultures incubated with lytic concentrations of PA and lethal toxin (LT) from B. anthracis. This assay represents an in vitro correlate of protection against anthrax disease. Cell viability was determined by measuring intracellular ATP. Results are presented in
Thus, ID delivery via HMN devices induces stronger anthrax neutralizing antibody titers than any other route of delivery. SMN enables topical delivery and induces anthrax neutralizing antibody titers that are as strong or stronger than those achieved via the IM injection. Notably, neutralizing antibodies were present in the HMN and SMN groups even in the absence of added adjuvant. Thus, the methods and devices of the present invention overcome the need for added adjuvants in the induction of a protective immune response to a vaccine. IN delivery also induced neutralizing antibody responses but required an adjuvant. Thus, IN delivery yields comparable results to IM injection but does so via non-invasive delivery without a needle.
II. Lethal Challenge Studies in a Rabbit Model
Delivery Routes:
Hollow microneedle (HMN)-based intradermal (ID) delivery: Injections into rabbits were made perpendicular to the skin surface, using a 34 gauge needle, with a 1 mm depth, on the end of a catheter line. The delivery rate was not controlled. The administration was performed by hand, over an about 20-30 second time span, using a rapid bolus injection. One hundred microliters of vaccine was administered, divided over 2 delivery sites per rabbit.
Solid microneedle (SMN) abrasion-based delivery: Rabbits were shaved with electric clippers then depilated using Nair® cream. Rabbits were then pre-treated with the SMN device, as described above. Vaccine (100 μl volume divided over 2 treatment sites, each of approximately 1×3 cm area) was then topically applied to the treated skin using a Gilson pipetter.
Topical delivery (no device): Rabbits were shaved with electric clippers then depilated using Nair® cream. Vaccine (100 μl volume divided over 2 treatment sites, each of approximately 1×3 cm area) was then topically applied to the treated skin using a Gilson pipetter.
Intramuscular (IM) injection: Vaccine (100 μl volume) was injected into the quadriceps muscle using a standard 30Ga needle and Icc syringe.
Intranasal (IN) (liquid formulation): Vaccine (100 μl volume) was sprayed into one nostril using a Penn-Century nasal sprayer device.
Intranasal (IN) delivery, with an aerodynamically light particle (ALP) formulation of the invention: Each capsule was filled with 10 mg of powder. Delivery was accomplished by pushing 5 ml of air through the device and into the nostril. Adjuvants: Alhydrogel (2% AL(OH)3; Superfos Biosector), CpG oligonucleotide (TCCATGACGTTCCTGACGTT; Proligo, LLC), 50 μg/rabbit.
Animals: New Zealand White (NZW) female rabbits
Immunization schedule: Rabbits were immunized at d0, d21 and d42
Antigen dose: 50 μg rPA per immunization
Number of animals: Total=n=6 or n=9 per group. Six animals from each group were subjected to lethal challenge. The remaining animals were sacrificed for broncheal alveolar lavage (BAL), nasal, or vaginal lavage on day 56. See Experimental Groups below
Sample Collection: Blood was collected on day 0 (“d0”, pre-bleed). d21 (prior to immunization 2), d35 (prior to immunization 3), and d56.
Assays: Assays were conventional and/or were performed as described elsewhere herein.
Serum total Ig titers were measured on day 21, 35 and 56. Serum from individual rabbits was analyzed for rPA-specific total rPA-specific total Ig by ELISA. BAL total Ig titers were measured on day 56. BAL IgA titers were measured on day 56. Nasal IgA titers were measured on day 56. Vaginal IgA titers were measured on day 56. Serum IgA titers were measured on day 56. PA/LT-neutralizing titers were determined in monocyte cell cultures on day 21, 35 and 56, as described above.
Lethal aerosol challenge was conducted with ˜100 LD50 anthrax spores, as described previously (Pitt et al., Vaccine 19:4768-4773, 2001). Challenge was performed 6 weeks following the 3rd dose of vaccine.
*Indicates groups with animals sacrificed for BAL, Nasal and Vaginal lavage.
Preparation of SFD rPA Particles:
For the dry powder SFD rPA samples used in this example, liquid particles were generated from solutions containing rPA and excipients using a BD AccuSpray nozzle as described in U.S. application Ser. No. 10/299,012. The volume mean diameter of liquid particles produced by this process is between about 50 μm and 100 μm. The frozen droplets were dried by lyophilization (freeze-drying, under vacuum), using a conventional lyophilization apparatus.
The compositions used in the rabbit challenge study were:
In the following examples, particles were frozen by spraying them into a vessel (such as a Virtis freeze-drying flask) containing liquid nitrogen, the vessel was then attached to a conventional lyophilizer and the excess liquid nitrogen evaporated off. The frozen aerosol was dried within about 48 hours to reach a moisture level below 3 wt %.
For sample 4, chitosan was spray freeze dried from a solution containing 20 wt % chitosan and 80 wt % trehalose, using a BD AccuSpray nozzle as described above. The SFD rPA and SFD chitosan were then blended by agitation in a vial.
Preparation of FD rPA Particles:
For the dry powderFD rPA samples used in this example, the frozen solution was dried by lyophilization (freeze-drying, under vacuum), using a conventional lyophilization apparatus. This method is generally called a “freeze-dry” or FD method, and compositions made by the method are called “freeze-dry” or FD compositions.
The compositions used in the rabbit challenge study were:
Solutions containing rPA, trehalose, and CpG were frozen by placing vials containing the solutions into a dry ice bath. The vials containing frozen solution were then dried using a conventional lyophilization apparatus to reach a moisture level below 3 wt %. For sample 3, the dried powder was then milled for 30 minutes using a “wiggle bug” ball mill. Sample 5 was prepared by adding to the dried sample SFD chitosan, which was prepared as described above, and milling for 30 minutes using a “wiggle bug” ball mill. This milling process results in samples with a volume mean diameter of between about 50 μm and 100 μm.
Serum antibody titers on day 21, day 35 and day 56 are presented in Tables 7-9.
After 1 dose of vaccine, the highest overall serum antibody response was in the ID-alum group, consistent with the results of the mouse study presented above. The arithmetic mean titer in this group was 142,933 as compared to a mean titer of 32,000 in the IM-alum group. IN delivery also induced significant serum antibody titers after a single dose of vaccine, although generally lower than those achieved by ID or IM injection. Rabbits immunized IN with the SFD powder formulation containing chitosan and CpG adjuvant generated the strongest overall IN-induced response with a mean serum titer of 10,500 as compared to a titer of 2016 in the group immunized IN with the standard liquid formulation.
SMN devices enabled topical delivery of anthrax vaccine, as significant antibody reponses were generated after 1 dose of vaccine in groups 7 and 14, whereas none of the rabbits in the topical group (group 8) generated a detectable response.
After the 2nd dose of vaccine, all groups showed a significant rise in serum antibody titers. As after the first dose, the strongest overall response was generated in the HMN ID-alum group with a mean titer of 3,003,733 as compared to a mean of 2,321,067 in rabbits immunized IM with rPA plus alum.
After the 3rd dose of vaccine, all groups were positive for PA-specific antibodies in the serum. Overall, the ID and IM induced titers were highest, followed by IN, SMN and topical.
Tables 10-12 show antibody titers on day 56 in various tissues. Table 10 shows PA-specific IgA titers in BAL fluid; Table 11 shows PA-specific IgA titers in nasal fluid; Table 12 shows PA-specific IgA titers in vaginal fluid. The results presented in Table 10 show that the anthrax vaccine compositions and methods of the present invention induce mucosal immune responses in the BAL. The results presented in Table 11 show that the anthrax vaccine composition and methods of the present invention induce mucosal immune responses in the nasal cavity. The results presented in Table 12 show that the anthrax vaccine composition and methods of the present invention induce mucosal immune responses in the vaginal tissue, a remote mucosal tissue distant from the sites of vaccine administration.
Anthrax neutralization from was measured by adding dilutions of rabbit sera from vaccinated or control animals to monocyte cell cultures incubated with lytic concentrations of PA and lethal toxin (LT) from B. anthracis. This assay represents an in vitro correlate of protection against anthrax disease. Cell viability was determined by measuring intracellular ATP. Results are presented in
Data obtained with various types of administration are summarized in Table 13.
1Ames strain, provided by Dr. Bruce Ivins, Division of Bacteriology, USAMRIID.
2Overall number of aerosol LD50s given calculated at 103 ± 44 (mean ± S.D.).
3Amount in parenthesis is per vaccination.
4Liquid antigen/adjuvant formulation.
5Spray freeze-dried powder antigen/adjuvant formulation.
6Freeze-dried powder antigen/adjuvant formulation.
The current standard for anthrax vaccination consists of IM injection of vaccine containing alum as adjuvant. In this study, this standard provided partial protection (83%) against lethal challenge (Table 13). In contrast, HMN-based ID delivery of rPA plus alum or rPA without adjuvant provided complete protection (100%). In general, choice of adjuvant for IM or ID groups did not seem to play a major role in determining protective efficacy at the dose of rPA employed in this study. IN delivery of a liquid formulation provided 67% protection, while IN delivery of the powder formulation of the present invention provided complete protection (100%). SMN-based topical delivery provided up to 50% protection as compared to only 17% by topical administration in the absence of a device. Overall, the results of the lethal challenge study demonstrate that by targeting the skin and nasal mucosa via the methods and formulations of the present invention, complete protection against anthrax can be achieved. This is the first time that protection has been demonstrated through targeting of the very tissues through which anthrax disease is acquired in natural and weaponized forms of the pathogen (i.e, skin and respiratory systems).
The results of the mouse and rabbit studies presented above show that ID delivery via HMN provides stronger immune responses than IM injection after a single dose of vaccine. Thus, ID delivery via HMN may enable a reduction in the number of required doses of anthrax vaccine to elicit protective effect. Also, based on these results, it is anticipated that ID delivery via HMN may provide dose sparing benefits; i.e., may enable one to use a reduced amount of rPA per dosage to achieve the same or greater level of immune response and protection as that achieved using the full dose of vaccine via the IM route.
From the foregoing description, one skilled in the art can easily ascertain the essential characteristics of this invention, and without departing from the spirit and scope thereof, can make changes and modifications of the invention to adapt it to various usage and conditions.
Without further elaboration, it is believed that one skilled in the art can, using the preceding description, utilize the present invention to its fullest extent. The preceding preferred specific embodiments are, therefore, to be construed as merely illustrative, and not limitative of the remainder of the disclosure in any way whatsoever.
The entire disclosure of all applications, patents and publications, cited above and in the figures are hereby incorporated by reference.
| Number | Date | Country | |
|---|---|---|---|
| 60446995 | Feb 2003 | US | |
| 60486460 | Jul 2003 | US |
