Invented by Jong-Sang Park, Min-Hyo Seo, Samyang Biopharmaceuticals Corp
The Samyang Biopharmaceuticals Corp invention works as followsThe disclosure is a biodegradable and positively charged aminoalkyl polymer that can be used to deliver bioactive agents such as drugs, DNA, RNA oligonucleotides peptides proteins. The polymer can be modified to allow biologically active molecules, such as drugs or ligands.
Background for Positively charged poly[alpha-(omega-aminoalkyl) glycolic acid] for the delivery of a bioactive agent via tissue and cellular uptake
This invention is about the delivery of a biological agent. The invention is more specifically a composition for delivery of bioactive agents such as drugs, DNA, RNA and oligonucleotides.
In the past two decades, the concept of using polymers to release active drugs or other therapeutic compounds in medical applications has been developed and refined extensively.
When polymers are used to deliver pharmacologically-active agents in vivo it is important that the polymers be nontoxic, and that as they are eroded by body fluids, the polymer degrades into non-toxic degradation product. Many synthetic biodegradable materials, however, produce oligomers or monomers that negatively interact with surrounding tissue. D. F. Williams, 17 J. Mater. Sci. 1233 (1982). Polymers based on naturally-occurring metabolites have been developed to minimize the toxic effects of the intact polymer and its degradation products. The polyesters and polyamides made from amino acids or lactic acid are probably the best studied.
Bioerodable or degradable polymers can be used to control the release of pharmaceuticals. U.S. Pat., for instance, describes such polymers. No. 4,291,013; U.S. Pat. No. 4,347,234; U.S. Pat. No. 4,525,495; U.S. Pat. No. 4,570,629; U.S. Pat. No. 4,572,832; U.S. Pat. No. 4,587,268; U.S. Pat. No. 4,638,045; U.S. Pat. No. 4,675,381; U.S. Pat. No. No. 4,745,160 and U.S. Pat. No. 5,219,980. The U.S. Pat. No. No. “The products of hydrolysis include 4-amino-2 hydroxy butanoic and 4-amino-3 hydroxy butanoic acids which are not precursors to the twenty naturally occurring amino acids and are therefore not as biocompatible as would be desired.
The biodegradable polymers, polylactic acid, polyglycolic acid, and polylactic-glycolic acid copolymer (PLGA), have been investigated extensively for nanoparticle formulation. These polymers are polyesters that, upon implantation in the body, undergo simple hydrolysis. The products of such hydrolysis are biologically compatible and metabolizable moieties (i.e. lactic acid and glycolic acid), which are eventually removed from the body by the citric acid cycle. Polymer biodegradation products are formed at a very slow rate, hence do not affect normal cell function. Drug release from these polymers occurs by two mechanisms. First, diffusion results in the release of the drug molecules from the implant surface. Second, subsequent release occurs by the cleavage of the polymer backbone, defined as bulk erosion. Several implant studies with these polymers have proven safe in drug delivery applications, used in the form of matrices, microspheres, bone implant materials, surgical sutures, and also in contraceptive applications for long-term effects. These polymers are also used as graft materials for artificial organs, and recently as basement membranes in tissue engineering investigations. 2 Nature Med. 824-826 (1996). Thus, these polymers have been time-tested in various applications and proven safe for human use. Most importantly, these polymers are FDA-approved for human use.
Nanoparticles, due to their sub-cellular sizes, are thought to enhance interfacial cell uptake and achieve a “local pharmacological effect”. The hypothesis is that nanoparticles would enhance the cellular uptake (due endocytosis), compared to free drugs. Several investigators have demonstrated that nanoparticle-entrapped agents have higher cellular uptake by endocytosis and prolonged retention compared to the free drugs. Thus, nanoparticle-entrapped drugs have enhanced and sustained concentrations inside cells and hence enhanced therapeutic drug effects in inhibiting proliferative response. Furthermore, nanoparticle-entrapped drugs are protected from metabolic inactivation before reaching the target site, as often happens with upon the systemic administration of free drugs. The effective local dose of nanoparticles required to achieve the local pharmacologic effect could be several times lower than systemic or oral dosages.
Nanoparticles are being investigated in cancer treatment for their use as drug carriers for tumor localization, intracellular targeting of antiviral and antibacterial agents, targeting the reticuloendothelial (parasitic) system, as immunological adjuvants (by subcutaneous and oral routes), ocular drug delivery for sustained action and prolonged systemic therapy. “263 Science 1600-1603 (1996).
The surface of nanoparticles or microspheres and the cell membranes have a negative charge, so cellular uptake will be very low. The cell membranes repel PLGA nanoparticles or microspheres. They cannot penetrate the cells.
Since the mid-1950’s efforts to identify methods of delivery of nucleic acid in tissue culture cell, H. E. Alexander and al., 5 Virol. 172-173 (1958), there has been steady progress in improving the delivery of functional DNA and RNA in vitro and In vivo. The delivery and expression of nucleic acid is a subject that continues to attract scientific attention. In vivo, methods for delivering non-replicating functional plasmids are still in their infancy. However, some success has already been achieved in vitro. E. R. Lee and colleagues, 7 Human Gene Therapy, 1701-1717, 1996, and cationic polymers (B. A. Demeneix et al., 7 Human Gene Therapy 1947-1954 (1996); A. V. Kabanov et al., 6 Bioconjugate Chem. 7-20 (1995); E. Wagner, 88 Proc. Nat’l Acad. Sci. USA 4255-4259 (1991), viral vectors, A. H. Jobe et al., 7 Human Gene Therapy 697-704 (1996); J. Gauldie, 6 Curr. Opinion Biotech. 590-595 (1995). Each of the methods above has its own limitations and disadvantages. Viral vectors are more efficient than non-viral ones, but they have several disadvantages. These include targeting only dividing cell, random DNA insert, the risk of replication and host immune reactions. J. M. Wilson et al., 96 J. Clin. Invest. 2547-2554 (1995).
Compared to viral Vectors, Nonviral vectors can be easily made and are less likely to cause immune reactions. There is also no replication reaction. In vitro, transfection efficiency can reach close to 100% under certain conditions. In general, these nonviral vectors are ineffective at introducing genetic material into the cells and show low gene expression when used in vivo. For gene transfection, for example, cationic amphiphiles were used. F. D. Ledley. 6 Human Gene Therapy, 1129-1144 (1996). However, transfection efficiency with cationic vectors is not as high compared to viral vectors. There have also been complaints about cytotoxicity. “The biggest disadvantage of cationic fats is that they do not break down in the body, and are therefore very difficult to remove from there.
Several classes of cationic oligomers have been described to enhance the uptake of genetic material into cells, and its expulsion from endosomes. Dendrimers are polyamidoamine polymers whose diameter is determined by how many steps were taken to synthesize them. The complexes were constructed by combining dendrimers with different sizes and different ratios of drug charges (cationic DNA to anionic dendrimer). These complexes show efficient gene delivery in vitro into a variety cell types. F. D. Ledley. 6 Human Gene Therapy, 1129-1144 (1996). Other cationic polymers such as polyethylenimine and poly-L lysine have a uniformly high positive charge density. They will also complex with nucleic acid and DNA, and transfer nucleic acid into cells in vitro. These polymers can condense plasmids to form complexes of varying size and charge that interact with cell membranes by ionic interactions and enter cells through endocytosis. However, these cationic polymers are not biodegradable. They are toxic because they accumulate in the body. For example, it takes several years to degrade PLL completely in the body.
It is clear that a carrier which is non-toxic and biodegradable and can be used to deliver nucleic acid and other drugs efficiently would represent a significant advance in the field.
The present invention aims to provide a carrier that can be used to deliver a nucleic agent, drug or other bioactive agents to an individual who needs them.
It is also the object of this invention to provide nontoxic, biodegradable drug carriers.
It is also an object of the invention, to provide a carrier that delivers nucleic acid with high transfection efficiency.
These and other objects can be addressed by providing poly[?-(?-aminoalkyl) glycolic acid] for use in delivery of a bioactive agent. The invention is a biodegradable polymer of polyester represented by formula.
wherein R1 and R2 can be selected from the following group: H, carbohydrates, polyethylene glycol and their derivatives, drugs and peptides.
In a second preferred embodiment, the invention consists of a biodegradable amphiphilic block copolymer consisting:
(a), a first monomer represented by formula
wherein R1 and R2 can be selected from a group of drugs, polyethylene glycol and carbohydrates, and peptides.
(b) a second polymer bonded to the first polymer, wherein the second polymer is a member selected from the group consisting of poly(D-lactic acid), poly(L-lactic acid), poly(DL-lactic acid), poly(D-lactide), poly(L-lactide), poly(DL-lactide), polyglycolic acid, polyglycolides, poly(lactic-co-glycolic acids), and polycaprolactone.Click here to view the patent on Google Patents.