Pharmaceutical compositions

Details Pharmaceutical compositions Pharmaceutical compositions

1999-03-04

2002-10-15

LeGuyader, John L. (Department: 1635)

Drug, bio-affecting and body treating compositions

Designated organic active ingredient containing

Carbohydrate doai

C536S023100, C536S024310, C536S024500, C424S450000, C435S325000, C435S375000

Reexamination Certificate

active

06465439

ABSTRACT:

This invention relates to pharmaceutical compositions, particularly liposomal oligonucleotide compositions, their preparation and their use.
In WO 95/02069 there are described oligonucleotides specifically hybridizable with DNA or RNA derived from a protein kinase C (PKC) gene, which oligonucleotides are particularly for use in the diagnosis and treatment of neoplastic, hyperproliferative and inflammatory disorders associated with protein kinase C.
It has now been found that compositions retaining high activity after prolonged circulation in the bloodstream and exhibiting reduced accumulation of oligonucleotide in non-target organs such as the liver and kidney can be prepared by formulation of such oligonucleotides within sterically stabilised liposomes.
Accordingly, the present invention provides a pharmaceutical composition comprising (A) an oligonucleotide having 5 to 50 nucleotide units specifically hybridizable with DNA or RNA derived from a protein kinase C gene, entrapped in (B) sterically stabilised liposomes.
Hybridisation, in the context of nucleic acid chemistry, means hydrogen bonding, also known as Watson-Crick base pairing, between complementary bases, usually on opposite nucleic acid strands or two regions of a nucleic acid strand. Guanine and cytosine are examples of complementary bases which are known to form three hydrogen bonds between them. Adenine and thymine are examples of complementary bases which form two hydrogen bonds between them. “Specifically hybridizable” and “complementary” are terms which are used to indicate a sufficient degree of complementary such that stable and specific binding occurs between the DNA or RNA target and the oligonucleotide. It is understood that an oligonucleotide need not be 100% complementary to its target nucleic acid sequence to be specifically hybridizable.
An oligonucleotide is specifically hybridizable when binding of the oligonucleotide to the target interferes with the normal function of the target molecule to cause a loss of utility, and there is a sufficient degree of complementary to avoid non-specific binding of the oligonucleotide to non-target sequences under conditions in which specific binding is desired, i.e. under physiological conditions in the case of in vivo assays or therapeutic treatment, or, in the case of in vitro assays, under conditions in which the assays are conducted.
As used in the context of this invention, the term “oligonucleotide” refers to a substance having a plurality of nucleotide units formed from naturally occurring bases and sugars joined by phosphodiester internucleoside (backbone) linkages. The term “oligonucleotide” also includes analogues which function similarly to naturally occurring oligonucleotides but which have non-naturally occurring monomers (nucleotides) or portions thereof. These oligonucleotide analogues are often preferred over native forms because of properties such as enhanced cellular uptake, enhanced target binding affinity and increased stability in the presence of nucleases.
In preferred embodiments of the invention, the oligonucleotide (A) is specifically hybridizable with the translation initiation codon of the PKC gene, in which case it preferably comprises a CAT sequence, or with the 5′ untranslated region or 3′ untranslated region of the gene. In other preferred embodiments of the invention, the oligonucleotide (A) is specifically hybridizable with DNA or mRNA encoding a particular PKC isozyme (isoform) or a particular set of PKC isozymes.
The oligonucleotide (A) preferably comprises from 8 to 30 nucleotide units, more preferably 12 to 25 nucleotide units, especially 18 to 22 nucleotide units.
In some preferred oligonucleotides (A), at least one nucleotide is modified at the 2′ position of the sugar moiety. Certain preferred oligonucleotides (A) are chimeric oligonucleotides. “Chimeric oligonucleotides” or “chimeras”, in the context of this invention, are oligonucleotides which contain two or more chemically distinct regions, each made up of at least one nucleotide. These oligonucleotides typically contain at least one region of modified nucleotides that confers one or more beneficial properties (such as, for example, increased nuclease resistance, increased uptake into cells, increased binding affinity for the RNA target) and a region that is a substrate for RNase H cleavage. In one preferred embodiment, a chimeric oligonucleotide comprises at least one region modified to increase target binding affinity and, usually, a region that acts as a substrate for RNAse H. Affinity of an oligonucleotide for its target is routinely determined by measuring the Tm of an oligonucleotide/target pair, which is the temperature at which the oligonucleotide and target dissociate; dissociation is detected spectrophotometrically. The higher the Tm, the greater the affinity of the oligonucleotide for the target. In a more preferred embodiment, the region of the oligonucleotide which is modified to increase target binding affinity comprises at least one nucleotide modified at the 2′ position of the sugar, particularly a 2′-alkoxy, 2′-alkoxyalkoxy or 2′-fluoro-modified nucleotide. Such modifications are routinely incorporated into oligonucleotides and these oligonucleotides have been shown to have a higher Tm (i.e., higher target binding affinity) than 2′-deoxyoligonucleotides against a given target. In the chimeric oligonucleotides, the region which is a substrate for RNAse H comprises at least one 2′-deoxynucleotide. RNAse H is a cellular endonuclease that cleaves the RNA strand of RNA:DNA duplexes; activation of this enzyme therefore results in cleavage of the RNA target, and thus can greatly enhance the efficiency of antisense inhibition. Cleavage of the RNA target can be routinely demonstrated by gel electrophoresis. In another preferred embodiment, the chimeric oligonucleotide is also modified to enhance nuclease resistance. Cells contain a variety of exo- and endo-nucleases which can degrade nucleic acids. A number of nucleotide and nucleoside modifications have been shown to make the oligonucleotide into which they are incorporated more resistant to nuclease digestion than the native oligodeoxynucleotide. Nuclease resistance is routinely measured by incubating oligonucleotides with cellular extracts or isolated nuclease solutions and measuring the extent of intact oligonucleotide remaining over time, usually by gel electrophoresis. Oligonucleotides which have been modified to enhance their nuclease resistance survive intact for a longer time than unmodified oligonucleotides. A variety of oligonucleotide modifications have been demonstrated to enhance or confer nuclease resistance. Oligonucleotides which contain at least one phosphorothioate modification are presently more preferred. In some cases, oligonucleotide modifications which enhance target binding affinity are also, independently, able to enhance nuclease resistance.
Specific examples of some preferred oligonucleotides may contain phosphorothioate, phosphotriester, methyl phosphonate, short chain alkyl or cycloalkyl intersugar linkages or short chain heteroatomic or heterocyclic intersugar (“backbone”) linkages, e.g. amide-type linkages. Most preferred are phosphorothioates and those with CH
2
—NH—O—CH
2
, CH
2
—N(CH
3
)—O—CH
2
, CH
2
—O—N(CH
3
)—CH
2
, CH
2
—N(CH
3
)—N(CH
3
)—CH
2
and O—N(CH
3
)—CH
2
—CH
2
and CH
2
—C(O)—NH—CH
2
backbones (where phosphodiester is O—P—O—CH
2
). Also preferred are oligonucleotides having morpholino backbone structures, for example as described in U.S. Pat. No. 5,034,506. In other preferred embodiments, such as the protein-nucleic acid or peptide-nucleic acid (PNA) backbone, the phosphodiester backbone of the oligonucleotide may be replaced with a polyamide backbone, the bases being bound directly or indirectly to the aza nitrogen atoms of the polyamide backbone, as described by P. E. Nielsen, M. Egholm, R. H. Berg, O. Buchardt, Science 1991, 254, 1497. Other preferred oligonucleotides may contain sugar moieties comprising

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