Link:  Pharm/Biotech Resources

Title:  Methods and compositions for treatment of HIV-1 infection using antiviral compounds in simultaneous or sequential combinations

United States Patent:  6,861,059

Issued:  March 1, 2005

Inventors:  Johnson; M. Ross (Chapel Hill, NC); Lambert; Dennis Michael (Cary, NC)

Assignee:  Trimeris, Inc. (Durham, NC)

Appl. No.:  252136

Filed:  September 20, 2002

Abstract

Novel antiviral combinations for the treatment or prevention of viral infections, in particular, HIV, are disclosed. This new antiviral therapy employs either DP-178 or DP-107, viral fusion inhibitors, in combination with at least one other antiviral therapeutic agent. The combinations of the invention are better than single therapies alone, and in certain cases are synergistic. The use of DP-178 or DP-107 is an ideal therapy to combine with another antiviral, given both the novel mechanism which this therapeutic blocks HIV transmission and the non-toxicity of the therapeutic.

Description of the Invention

FIELD OF THE INVENTION

The present invention relates to methods of treating viral infections, particularly HIV infection, using novel combinational therapy. The novel combinational therapy employs either the peptide DP-178, DP-107 or fragments, analogs and/or homologs thereof, and at least one other therapeutic agent.

DP-178 is a peptide corresponding to amino acids 638 to 673 of the HIV-1_LAI transmembrane protein (TM) gp41. DP-178 includes portions, analogs, and homologs of DP-178, all of which exhibit antiviral activity. Antiviral activity includes, but is not limited to, the inhibition of HIV transmission to uninfected CD-4+ cells. Further, the invention relates to the use of DP-178 and DP-178 fragments and/or analogs or homologs as inhibitors of retroviral transmission, in particular HIV, to uninfected cells, in both humans and non-humans. The present invention also relates to the antiviral peptide DP-107, a peptide corresponding to amino acids 558 to 595 of the HIV-1_LAI transmembrane protein (TM) gp41, that are present in other enveloped viruses. More specifically, the invention is directed to the use of DP-107, fragments and/or analogs or homologs in combination with other therapeutic agents to treat viral infections, particularly HIV infection. Further, the invention encompasses novel pharmaceutical compositions comprising DP-178 or DP-107 and at least one other therapeutic agent.

BACKGROUND OF THE INVENTION

2.1. The Human Immunodeficiency Virus

The human immunodeficiency virus (HIV) is a pathogenic retrovirus and the causative agent of acquired immune deficiency syndrome (AIDS) and related disorders (Barre-Sinossi, F. et al., 1983, Science 220:868-870; Gallo, R. et al., 1984, Science 224:500-503). There are at least two distinct types of HIV: HIV-1 (Barre-Sinossi, F. et al., 1983, Science 220:868-870; Gallo, R. et al., 1984, Science 224:500-503) and HIV-2 (Clavel, F. et al., 1986, Science 223:343-346; Guyader, M. et al., 1987, Nature 326:662-669). Further, a large amount of genetic heterogeneity exists within populations of each of these types. Infection of human CD-4+ T-lymphocytes with an HIV virus leads to depletion of the cell type and eventually to opportunistic infections, neurological dysfunctions, neoplastic growth, and untimely death.

HIV is a member of the lentivirus family of retroviruses (Teich, N. et al., 1984; RNA Tumor Viruses, Weiss, R. et al., eds., CSH-press, pp. 949-956). Retroviruses are small enveloped viruses that contain a diploid, single-stranded RNA genome, and replicate via a DNA intermediate produced by a virally-encoded reverse transcriptase, an RNA-dependent DNA polymerase (Varmus, H., 1988, Science 240:1427-1439). Other retroviruses include, for example, oncogenic viruses such as human T-cell leukemia viruses (HTLV-1,-II,-III), and feline leukemiavirus. The HIV viral particle consists of a viral core, made up of proteins designated p24 and p18. The viral core contains the viral RNA genome and those enzymes required for replicative events. Myristylated gag protein forms an outer viral shell around the viral core, which is, in turn, surrounded by a lipid membrane envelope derived from the infected cell membrane. The HIV envelope surface glycoproteins are synthesized as a single 160 kD precursor protein which is cleaved by a cellular protease during viral budding into two glycoproteins, gp41 and gp120. gp41 is a transmembrane protein and gp120 is an extracellular protein which remains noncovalently associated with gp41, possibly in a trimeric or multimeric form (Hammerwskjold, M. and Rekosh, D., 1989, Biochem. Biophys. Acta 989:269-280).

HIV is targeted to CD-4+ T lymphocytes because the CD-4 surface protein acts as the cellular receptor for the HIV-1 virus (Dalgleish, A. et al., 1984, Nature 312: 767-768, Maddon et al., 1986, Cell 47:333-348). Viral entry into cells is dependent upon gp120 binding the cellular CD-4+ receptor molecules, while gp41 anchors the envelope glycoprotein complex in the viral membrane (McDougal, J. S. et al., 1986, Science 231:382-385; Maddon, P. J. et al., 1986, Cell 47:333-348) and thus explains HIV's tropism for CD-4+ cells.

2.2. HIV Treatment

HIV infection is pandemic and HIV associated diseases represent a major world health problem. Although considerable effort is being put into the successful design of effective therapeutics, currently no curative anti-retroviral drugs against AIDS exist. In attempts to develop such drugs, several stages of the viral life cycle have been considered targets for therapeutic intervention (Mitsuya, H. et al., 1991, FASEB J. 5:2369-2381). Intervention could potentially inhibit the binding of HIV to cell membranes, the reverse transcription of HIV RNA genome into DNA or the exit of the virus from the host cell and infection of new cellular targets.

Attempts are being made to develop drugs which can inhibit viral entry into the cell, the earliest stage of HIV infection. Here, the focus has been on CD-4+, the cell surface receptor for HIV. For example, recombinant soluble CD-4 has been shown to block HIV infectivity by binding to viral particles before they encounter CD-4 molecules embedded in cell membranes (Smith, D. H. et al., 1987, Science 238:1704-1707). Certain primary HIV-1 isolates are relatively less sensitive to inhibition by recombinant CD-4 (Daar, E. et al., 1990, Ann. Int. Med. 112:247-253). In addition, recombinant soluble CD-4 clinical trials have produced inconclusive results (Schooley, R. et al., 1990, Ann. Int. Med. 112:247-253; Kahn, J. O. et al., 1990, Ann. Int. Med. 112:254-261; Yarchoan, R. et al., 1989, Proc. Vth Int. Conf. on AIDS, p564, MCP 137).

The virally encoded reverse-transcriptase-targeted drugs, including 2',3'-dideoxynucleoside analogs such as AZT, ddI, ddC, and d4T, have been developed which have also been shown to be active against HIV (Mitsuya, H. et al., 1991, Science 249:1533-1544). While beneficial, these nucleoside analogs are not curative, probably due to the rapid appearance of drug resistant HIV mutants (Lander, B. et al., 1989, Science 243:1731-1734). In addition, the drugs often exhibit toxic side effects such as bone marrow suppression, vomiting, and liver function abnormalities.

The late stages of HIV replication, which involve crucial virus-specific secondary processing of certain viral proteins, have also been suggested as possible anti-HIV drug targets. Late stage processing is dependent on the activity of a viral protease, and drugs are being developed which inhibit this protease (Erikson, J., 1990, Science 249:527-533). The clinical outcome of these candidate drugs is still in question.

Attention is also being given to the development of vaccines for the treatment of HIV infection. The HIV-1 envelope proteins (gp160, gp120, gp41) have been shown to be the major antigens for anti-HIV antibodies present in AIDS patients (Barin et al., 1985, Science 228:1094-1096). Thus far, these proteins seem to be the most promising candidates to act as antigens for anti-HIV development. To this end, several groups have begun to use various portions of gp160, gp120, and/or gp41 as immunogenic targets for the host immune systems. See for example, Ivanoff, L. et al., U.S. Pat. No. 5,141,867; Saith, G. et al., WO 92/22, 654; Schafferman, A., WO 91/09,872; Formoso, C. et al., WO 90/07,119. Clinical results concerning these candidate vaccines, however, still remain far in the future.

Recently, double stranded RNAs, which elicit a general immune response, have been used in combination with antivirals such as interferon, AZT and phosphonoformate to treat viral infections. See Carter, W., U.S. Pat. No. 4,950,652. In addition, a therapy combining a pyrimidine nucleoside analog and a uridine phosphorylase inhibitor has been developed for the treatment of HIV, see Sommadossi, J. P. et al., U.S. Pat. No. 5,077,280. Although these specific therapies may prove to be beneficial, combination therapy in general has the potential for antagonism as demonstrated in vitro with azidothymidine (AZT) and ribavirin. See U.S. Pat. No. 4,950,652. Moreover, combination therapy is potentially problematic given the high toxicity of most anti-HIV therapeutics and their low level of effectiveness. Thus, there is a need for a combination therapy which is effective yet non-toxic.

The present invention provides a novel combination therapy based on the use of viral fusion inhibitors (DP-178 and DP-107, etc.) in combination with other antivirals. DP-178 and DP-107 are both novel therapeutics in that they prevent the virus from fusing with the cell, thereby very effectively preventing cell to cell transmission of the virus. In addition, DP-178 and DP-107 have proven to be non-toxic in in vitro studies and in animals. The present invention provides the first reported use of such peptides in combination with another antiviral or any other therapeutic agent.

SUMMARY OF THE INVENTION

The present invention relates to methods of treating or preventing viral infections, in particular HIV infections, in mammals, including humans, by administering an effective amount of DP-178, or a pharmaceutically acceptable derivative thereof in combination with at least one other therapeutic agent.

The present invention also relates to methods of treating or preventing viral infections, in particular HIV infections, in mammals, including humans, by administering an effective amount of DP-107 or pharmaceutically acceptable derivatives thereof in combination with at least one other therapeutic agent.

More specifically, the invention relates to methods of treating or preventing viral infections in mammals, including humans, by administering an effective amount of DP-107, DP-178, or a pharmaceutically acceptable derivative thereof, in combination with at least one other antiviral agent. The invention includes the administration of the active agents, e.g., DP-107, DP-178 or another antiviral either concomitantly or sequentially, including cycling therapy. Cycling therapy involves the administration of a first antiviral compound for a period of time, followed by the administration of a second antiviral compound for a period of time and repeating this sequential administration, i.e., the cycle, in order to reduce the development of resistance to one of the therapies. The invention encompasses combinations of DP-107, DP-178 or a pharmaceutically acceptable derivative thereof and at least one other therapeutic, particularly another antiviral, that are synergistic, i.e., better than either agent or therapy alone.

The invention also encompasses combinations of DP-178, DP-107 or a pharmaceutically acceptable derivative thereof with a least one other antiviral having a different site of action than the viral fusion inhibitor. Such a combination provides an improved therapy based on the dual action of these therapeutics whether the combination is synergistic or additive.

The present invention is also directed to methods of treating or preventing HIV infection in mammals, including humans, by administering an effective amount of DP-107, DP-178 or a pharmaceutically acceptable derivative thereof in combination with at least one other therapeutic agent, in particular at least one other antiviral.

The novel antiviral combinations of the present invention provide a means of treatment which may not only reduce the effective dose of either drug required for antiviral activity, thereby reducing toxicity, but may also improve the absolute antiviral effect, as a result of attacking the virus through multiple mechanisms. Similarly, the novel antiviral combinations provide a means for circumventing the development of viral resistance to a single therapy, thereby providing the clinician with a more efficacious treatment.

Another aspect of the invention encompasses pharmaceutical compositions and formulations for treating or preventing viral infections, in particular HIV infections, wherein said compositions comprise an effective amount of DP-178, DP-107, or a pharmaceutically acceptable derivative thereof, at least one additional therapeutic agent and a pharmaceutically acceptable carrier.

Therapeutic agents to be used in combination with DP-178, DP-107 or a pharmaceutically acceptable derivative thereof encompass a wide variety of known treatments. Preferably, the combinations employ DP-107 or DP-178 in combination with agents with a different mode of attack. Such agents include but are not limited to: antivirals, such as cytokines, e.g., rIFN .alpha., rIFN .beta., rIFN .gamma.; inhibitors of reverse transcriptase, e.g., AZT, 3TC, D4T, ddI, and other dideoxynucleosides or dideoxyfluoronucleosides; inhibitors of viral mRNA capping, such as ribavirin; inhibitors of HIV protease, such as ABT-538 and MK-639; amphotericin B as a lipid-binding molecule with anti-HIV activity; and castanospermine as an inhibitor of glycoprotein processing.

Thus, the present invention provides an improved antiviral therapy for treating a broad spectrum of viruses including HIV.

The present invention also provides combinational therapy which yields improved efficacy over either agent used as a single-agent therapy.

In addition, the invention provides combinational therapy which allows for reduced toxicity of DP-178 and DP-107 and/or the therapeutic agent with which the peptides are used; thereby providing a higher therapeutic index.

The instant invention provides a combinational therapy which provides a means for circumventing the development of viral resistance to a single therapy.

DETAILED DESCRIPTION OF THE INVENTION

The invention relates to methods of treating HIV infection in mammals, including humans which comprises administering an effective amount of DP-107, DP-178 or a pharmaceutically acceptable derivative thereof and an effective amount of at least one other therapeutic agent. Preferably, the therapeutic agent is another antiviral agent.

The present method provides an improved treatment for viral infection, specifically HIV infection. Specifically, the invention provides synergistic combinations for the treatment of HIV infection which comprise an effective amount of DP-178, DP-107 or pharmaceutically acceptable derivatives thereof and at least one member of a wide range of antiviral compounds available for the treatment of viral diseases. DP-178, DP-107 or a pharmaceutically acceptable derivative thereof is preferably used in combination with retrovirus inhibitors, viral protease inhibitors, cytokines or cytokine inhibitors or viral fusion inhibitors. The combinations of the present invention are administered to a patient in an amount sufficient to inhibit viral activity, to inhibit viral expression, or to inhibit viral transmission.

The method of the invention encompasses combination therapy in which DP-178, DP-107 and at least one other therapeutic agent are administered either concomitantly, e.g., as an admixture, separately but simultaneously or concurrently; or sequentially, including cycling therapy. Cycling therapy involves the administration of a first antiviral compound for a period of time, followed by the administration of a second antiviral compound for a period of time and repeating this sequential administration, i.e., the cycle, in order to reduce the development of resistance to one of the therapies. The invention also encompasses cycling therapy which comprises the administration of a first peptide of the present invention, followed by another antiviral, followed by another peptide of the present invention, etc., such that both viral fusion inhibitors DP-107 and DP-178 or derivatives thereof are used in combination with other antivirals. The invention also encompasses the use of a combination of the peptides, e.g., DP-107 in combination with DP-178.

Administration of DP-178, DP-107 or a pharmaceutically acceptable derivative thereof and one or more therapeutics "in combination" includes presentations in which both agents are administered together as a therapeutic mixture, and also procedures in which the two agents are administered separately but simultaneously, e.g., as through separate intravenous lines into the same individual. Administration "in combination" further includes the separate administration of one of the drugs given first, followed by the second.

The Applicants' novel therapy involves the use of peptides which inhibit viral fusion and cell to cell transmission of the virus in combination with another therapeutic. Without being limited by theory, the present invention is based, in part, on the belief that HIV is believed to be replicating 24 hours a day from the first day of infection. Therefore it may be beneficial to use antiviral treatment at different stages of the viral infection.

The combinations disclosed herein present the first known use of viral fusion inhibitors, acting at the first stage of viral infection, in combination with antivirals having different targets of action.

The DP-178 and DP-107 site of action is at the surface of the virus, preventing free virus from infecting host cells and cell-cell transmission of the virus. Therefore, without being limited by theory, Applicants believe that DP-178 or DP-107 used in combination with one or more drugs having different targets or mechanisms of action provides either an additive or synergistic effect. The combinations of the present invention are advantageous in that the drugs employed will be used at lower, less toxic concentrations. Combination therapy may not only reduce the effective dose of a drug required for antiviral activity, thereby reducing its toxicity, but may also improve the absolute antiviral effect as a result of attacking the virus through multiple mechanisms. Finally, the combinations of the present invention also provide a means for circumventing or decreasing the chance of development of viral resistance.

The preferred treatments to be used in combination with DP-178 and/or DP-107 include but are not limited to five different modes of attack on the virus: inhibition of the reverse transcriptase, inhibition of viral mRNA capping, inhibition of the HIV protease, inhibition of protein glycosylation, and inhibition of viral fusion. Agents which employ these modes of attack include, but are not limited to, antivirals, such as cytokines, e.g., rIFN .alpha., rIFN .beta., rIFN .gamma.; inhibitors of reverse transcriptase, such as AZT, 3TC, D4T, ddI, and dideoxyfluoronucleosides; inhibitors of viral mRNA capping, such as ribavarin; inhibitors of HIV protease, such as ABT-538 and MK-639; amphotericin B as a lipid-binding molecule with anti-HIV activity; and castanospermine as an inhibitor of glycoprotein processing.

5.1. Treatment of HIV with DP-178 or DP-107

5.1.1. DP-178 and DP-107 Peptides

DP-178 and DP-107 are peptides that exhibit potent antiviral activity by inhibiting virus fusion. These peptides include DP-178, a gp41 derived 36 amino acid peptide, fragments and/or analogs of DP-178, and peptides homologous to DP-178. In addition, these peptides may include peptides exhibiting antiviral activity which are analogous to DP-107, a 38 amino acid peptide, corresponding to residues 558 to 595 of the HIV-1_LAI transmembrane gp41 protein, and which are present in other enveloped viral proteins. The use of the peptides of the invention as inhibitors of non-human and human and retroviral, especially HIV transmission are detailed herein and in U.S. patent application Ser. No. 08/073,028, filed Jun. 7, 1993, U.S. patent application Ser. No. 08/264,531, filed Jun. 23, 1994, U.S. patent application Ser. No. 08/255,208, filed Jun. 7, 1994, U.S. patent application Ser. No. 08/360,107, filed Dec. 20, 1994, U.S. patent application Ser. No. 08/374,666, filed Jan. 27, 1995, U.S. patent application Ser. No. 08/470,896, filed Jun. 6, 1995, and U.S. patent application Ser. No. 08/485,264, filed Jun. 7, 1995, which are incorporated by reference herein in their entirety.

While not limited to any theory of operation, the following model is proposed to explain the potent anti-HIV activity of DP-178. In the viral protein, gp41, DP-178 corresponds to a putative a-helix region located in the C-terminal end of the gp41 ectodomain, and appears to associate with a distal site on gp41 whose interactive structure is influenced by the leucine zipper motif, a coiled-coil structure, referred to as DP-107. The association of these two domains may reflect a molecular linkage or "molecular clasp" intimately involved in the fusion process. It may be that the leucine zipper motif is involved in membrane fusion while the C-terminal .alpha.-helix motif serves as a molecular safety mechanism to regulate the availability of the leucine zipper during virus induced membrane fusion.

When synthesized as peptides both DP-107 and DP-178 are potent inhibitors of HIV infection and fusion, probably by virtue of their ability to form complexes with viral gp41 and interfere with its fusogenic process; e.g., during the structural transition of the viral protein from the native structure to the fusogenic state, the DP-107 and DP-178 peptides may gain access to their respective binding sites on the viral gp41, and exert a disruptive influence.

A truncated recombinant gp41 protein corresponding to the ectodomain of gp41 containing both DP-107 and DP-178 domains (excluding the fusion peptide, transmembrane region and cytoplasmic domain of gp41) did not inhibit HIV-1 induced fusion. However when a single mutation was introduced to disrupt the coiled-coil structure of the DP-107 domain--a mutation which results in a total loss of biological activity of DP-107 peptides--the inactive recombinant protein was transformed to an active inhibitor of HIV-1 induced fusion. This transformation may result from liberation of the potent DP-178 domain from a molecular clasp with the leucine zipper, DP-107 domain.

The peptide DP-178 of the invention corresponds to amino acid residues 638 to 673 of the transmembrane protein gp4l from the HIV-1_LAI isolate, and has the 36 amino acid sequence (reading from the amino to carboxy terminus):

NH2-YTSLIHSLIEESQNQQEKNEQELLELDKWASLWNWF-COOH (SEQ ID:1)

DP-178 is also described in Applicant's co-pending U.S. patent application Ser. No. 08/470,896, filed Jun. 6, 1995, Ser. No. 08/374,666, filed Jan. 27, 1995, Ser. No. 08/264,531, filed Jun. 23, 1994, and Ser. No. 08/255,208, filed Jun. 7, 1994, which are incorporated herein by reference in their entirety.

In addition to the full length DP-178 (SEQ ID:1) 36mer, the peptides of the invention may include truncations of the DP-178 (SEQ ID:1) peptide which exhibit antiviral activity. Such truncated DP-178 (SEQ ID:1) peptides may comprise peptides of between 3 and 36 amino acid residues (i.e., peptides ranging in size from a tripeptide to a 36-mer polypeptide), and may include but are not limited to those listed in Tables I and II, below. Peptide sequences in these tables are listed from amino (left) to carboxy (right) terminus. "X" may represent an amino group (--NH₂) and "Z" may represent a carboxyl (--COOH) group. Alternatively, as described below, "X" and/or "Z" may represent a hydrophobic group, an acetyl group, a FMOC group, an amido group, or a covalently attached macromolecule.

DP-107 is a 38 amino acid peptide corresponding to residues 558 to 595 of HIV-1_LAI transmembrane (TM) gp41 protein, which exhibits potent antiviral activity. DP-107 is an HIV-1-derived antiviral peptide and may also be found in other, non-HIV-1 envelope viruses. DP-107 is more fully described in Applicant's co-pending U.S. patent application Ser. No. 08/470,896, filed Jun. 6, 1995, Ser. No. 08/374,666, filed Jan. 27, 1995, Ser. No. 08/264,531, filed Jun. 23, 1994, and Ser. No. 08/255,208, filed Jun. 7, 1994, which are incorporated herein by reference in their entirety.

Deletions of DP107 or DP178 truncations are also within the scope of the invention. Such deletions consist of the removal of one or more amino acids from the DP107 or DP107-like peptide sequence, with the lower limit length of the resulting peptide sequence being 4 to 6 amino acids. Such deletions may involve a single contiguous or greater than one discrete portion of the peptide sequences. One or more such deletions may be introduced into DP107 or DP107 truncations, as long as such deletions result in peptides which may still be recognized by the 107x178x4, ALLMOTI5 or PLZIP search motifs described herein, or may, alternatively, exhibit antifusogenic or antiviral activity, or exhibit the ability to modulate intracellular processes involving coiled-coil peptide structures.

DP107 and DP107 truncations are more fully described in Applicants' co-pending U.S. patent application Ser. No. 08/374,666, filed Jan. 27, 1995, and which is incorporated herein by reference in its entirety.

The one letter amino acid code is used.

Additionally,

"X" may represent an amino group, a hydrophobic group, including but not limited to carbobenzoxyl, dansyl, or T-butyloxycarbonyl; an acetyl group; a 9-fluorenylmethoxy-carbonyl (FMOC) group; a macromolecular carrier group including but not limited to lipid-fatty acid conjugates, polyethylene glycol, or carbohydrates.

"Z" may represent a carboxyl group; an amido group; a T-butyloxycarbonyl group; a macromolecular carrier group including but not limited to lipid-fatty acid conjugates, polyethylene glycol, or carbohydrates.

The one letter amino acid code is used.

Additionally,

"X" may represent an amino group, a hydrophobic group, including but not limited to carbobenzoxyl, dansyl, or T-butyloxycarbonyl; an acetyl group; a 9-fluorenylmethoxy-carbonyl group; a macromolecular carrier group including but not limited to lipid-fatty acid conjugates, polyethylene glycol, or carbohydrates.

"Z" may represent a carboxyl group; an amido group; a T-butyloxycarbonyl group; a macromolecular carrier group including but not limited to lipid-fatty acid conjugates, polyethylene glycol, or carbohydrates.

5.1.2. DP-178 and DP-107 Analogs and Homologs

The antiviral peptides of the invention also include analogs of DP-178 and/or DP-178 truncations which may include, but are not limited to, peptides comprising the DP-178 (SEQ ID:1) sequence, or DP-178 truncated sequence, containing one or more amino acid substitutions, insertions and/or deletions. Analogs of DP-178 homologs, described below, are also within the scope of the invention. The DP-178 analogs of the invention exhibit antiviral activity, and may, further, possess additional advantageous features, such as, for example, increased bioavailability, and/or stability, or reduced host immune recognition.

HIV-1 and HIV-2 envelope proteins are structurally distinct, but there exists a striking amino acid conservation within the DP-178-corresponding regions of HIV-1 and HIV-2. The amino acid conservation is of a periodic nature, suggesting some conservation of structure and/or function. Therefore, one possible class of amino acid substitutions would include those amino acid changes which are predicted to stabilize the structure of the DP-178 peptides of the invention.

Amino acid substitutions may be of a conserved or non-conserved nature. Conserved amino acid substitutions consist of replacing one or more amino acids of the DP-178 (SEQ ID:1) peptide sequence with amino acids of similar charge, size, and/or hydrophobicity characteristics, such as, for example, a glutamic acid (E) to aspartic acid (D) amino acid substitution. When only conserved substitutions are made, the resulting peptide is functionally equivalent to DP-178 (SEQ ID:1) or the DP-178 peptide from which it is derived. Non-conserved substitutions consist of replacing one or more amino acids of the DP-178 (SEQ ID:1) peptide sequence with amino acids possessing dissimilar charge, size, and/or hydrophobicity characteristics, such as, for example, a glutamic acid (E) to valine (V) substitution.

Amino acid insertions may consist of single amino acid residues or stretches of residues ranging from 2 to 15 amino acids in length. One or more insertions may be introduced into DP-178 (SEQ ID:1), DP-178 fragments, analogs and/or DP-178 homologs.

Deletions of DP-178 (SEQ ID:1), DP-178 fragments, analogs, and/or DP-178 homologs are also within the scope of the invention. Such deletions consist of the removal of one or more amino acids from the DP-178 or DP-178-like peptide sequence, with the lower limit length of the resulting peptide sequence being 4 to 6 amino acids. Such deletions may involve a single contiguous or greater than one discrete portion of the peptide sequences.

The peptides of the invention may further include homologs of DP-178 (SEQ ID:1) and/or DP-178 truncations which exhibit antiviral activity. Such DP-178 homologs are peptides whose amino acid sequences are comprised of the amino acid sequences of peptide regions of other (i.e., other than HIV-1_LAI) viruses that correspond to the gp4l peptide region from which DP-178 (SEQ ID:1) was derived. Such viruses may include, but are not limited to, other HIV-1 isolates and HIV-2 isolates. DP-178 homologs derived from the corresponding gp4l peptide region of other (i.e., non HIV-1_LAI) HIV-1 isolates may include, for example, peptide sequences as shown below.

SEQ ID:3 (DP-185), SEQ ID:4, and SEQ ID:5 are derived from HIV-1_SF2, HIV-1_RF, and HIV-1_MN isolates, respectively. Underlined amino acid residues refer to those residues that differ from the corresponding position in the DP-178 (SEQ ID:1) peptide. One such DP-178 homolog, DP-185 (SEQ ID:3), is described in the Working Example presented in Section 6, below, where it is demonstrated that DP-185 (SEQ ID:3) exhibits antiviral activity. The DP-178 homologs of the invention may also include truncations, amino acid substitutions, insertions, and/or deletions, as described above.

In addition, striking similarities, as shown in FIG. 1, exist within the regions of HIV-1 and HIV-2 isolates which correspond to the DP-178 sequence. A DP-178 homolog derived from the HIV-2_NIHZ isolate has the 36 amino acid sequence (reading from amino to carboxy terminus):

NH₂ -LEANISQSLEQAQIQQEKNMYELQKLNSWDVFTNWL-COOH (SEQ ID:7)

Table III and Table IV show some possible truncations of the HIV-2_NIHZ DP-178 homolog, which may comprise peptides of between 3 and 36 amino acid residues (i.e., peptides ranging in size from a tripeptide to a 36-mer polypeptide). Peptide sequences in these tables are listed from amino (left) to carboxy (right) terminus. "X" may represent an amino group (--NH₂) and "Z" may represent a carboxyl (--COOH) group. Alternatively, as described below, "X" and/or "Z" may represent a hydrophobic group, an acetyl group, a FMOC group, an amido group, or a covalently attached macromolecule, as described below.

The one letter amino acid code is used.

Additionally,

"X" may represent an amino group, a hydrophobic group, including but not limited to carbobenzoxyl, dansyl, or T-butyloxycarbonyl; an acetyl group; a 9-fluorenylmethoxy-carbonyl (FMOC) group; a macromolecular carrier group including but not limited to lipid-fatty acid conjugates, polyethylene glycol, or carbohydrates.

"Z" may represent a carboxyl group; an amido group; a T-butyloxycarbonyl group; a macromolecular carrier group including but not limited to lipid-fatty acid conjugates, polyethylene glycol, or carbohydrates.

The one letter amino acid code is used.

Additionally,

"X" may represent an amino group, a hydrophobic group, including but not limited to carbobenzoxyl, dansyl, or T-butyloxycarbonyl; an acetyl group; a 9-fluorenylmethoxy-carbonyl (FMOC) group; a macromolecular carrier group including but not limited to lipid-fatty acid conjugates, polyethylene glycol, or carbohydrates.

"Z" may represent a carboxyl group; an amido group; a T-butyloxycarbonyl group; a macromolecular carrier group including but not limited to lipid-fatty acid conjugates, polyethylene glycol, or carbohydrates.

5.1.3. Preparation of DP-178 and DP-107

The peptides of the invention may be synthesized or prepared by techniques well known in the art. See, for example, Creighton, 1983, Proteins: Structures and Molecular Principles, W. H. Freeman and Co., NY, which is incorporated herein by reference in its entirety. Short peptides, for example, can be synthesized on a solid support or in solution. Longer peptides amy be made using recombinant DNA techniques. Here, the nucleotide sequences encoding the peptides of the invention may be synthesized, and/or cloned, and expressed according to techniques well known to those of ordinary skill in the art. See, for example, Sambrook, et al., 1989, Molecular Cloning, A Laboratory Manual, Vols. 1-3, Cold Spring Harbor Press, NY.

The peptides of the invention may alternatively be synthesized such that one or more of the bonds which link the amino acid residues of the peptides are non-peptide bonds. These alternative non-peptide bonds may be formed by utilizing reactions well known to those in the art, and may include, but are not limited to imino, ester, hydrazide, semicarbazide, and azo bonds, to name but a few. In yet another embodiment of the invention, peptides comprising the sequences described above may be synthesized with additional chemical groups present at their amino and/or carboxy termini, such that, for example, the stability, bioavailability, and/or inhibitory activity of the peptides is enhanced. For example, hydrophobic groups such as carbobenzoxyl, dansyl, or t-butyloxycarbonyl groups, may be added to the peptides' amino termini. Likewise, an acetyl group or a 9-fluorenylmethoxy-carbonyl group may be placed at the peptides' amino termini. (See "X" in Tables I to IV, above.) Additionally, the hydrophobic group, t-butyloxycarbonyl, or an amido group may be added to the peptides' carboxy termini. (See "Z" in Tables I to IV, above.) Further, the peptides of the invention may be synthesized such that their steric configuration is altered. For example, the D-isomer of one or more of the amino acid residues of the peptide may be used, rather than the usual L-isomer. Still further, at least one of the amino acid residues of the peptides of the invention may be substituted by one of the well known non-naturally occurring amino acid residues. Alterations such as these may serve to increase the stability, bioavailability and/or inhibitory action of the peptides of the invention.

Any of the peptides described above may, additionally, have a non-peptide macromolecular carrier group covalently attached to their amino and/or carboxy termini. Such macromolecular carrier groups may include, for example, lipid-fatty acid conjugates, polyethylene glycol, or carbohydrates. The truncations, analogs and homologs of DP-178 and DP-107 are described fully in Applicant's co-pending application Ser. No. 08/073,028, filed Jun. 7, 1993, Ser. No. 08/264,531, filed Jun. 23, 1994, Ser. No. 08/255,208, filed Jun. 7, 1994 and Ser. No. 08/360,107, filed Dec. 20, 1994, which are incorporated herein by reference in their entirety.

5.1.4. Therapeutic Uses of the Peptides of the Invention

The DP-178 (SEQ ID:1) peptides of the invention, and DP-178 fragments, analogs, and homologs, exhibit potent antiviral activity. The DP-107-like and DP-178-like peptides of the invention preferably exhibit antiviral activity. As such, the peptides may be used as inhibitors of human and non-human viral and retroviral, especially HIV, transmission to uninfected cells.

The human retroviruses whose transmission may be inhibited by the peptides of the invention include, but are not limited to all strains of HIV-1 and HIV-2 and the human T-lymphocyte viruses (HTLV-I and II). The non-human retroviruses whose transmission may be inhibited by the peptides of the invention include, but are not limited to bovine leukosis virus, feline sarcoma and leukemia viruses, simian immunodeficiency, sarcoma and leukemia viruses, and sheep progress pneumonia viruses.

Non retroviral viruses whose transmission may be inhibited by the peptides of the invention include, but are not limited to human respiratory syncytial virus, canine distemper virus, newcastle disease virus, human parainfluenza virus, and influenza viruses.

The invention further encompasses the treatment of the above retroviral and non-retroviral viruses using the peptides in combination therapy.

5.2. Antivirals to be Used in Combination with DP-178 or DP-107

According to the present invention, DP-178 or DP-107, a virus fusion inhibitor, may be used in combination with other therapeutic agents to enhance its antiviral effect achieved. Preferably DP-178 or DP-107 is used in combination with another antiviral agent. Such additional antiviral agents which may be used with DP-178 or DP-107 include but are not limited to those which function on a different target molecule involved in viral replication, e.g., reverse transcriptase inhibitors, viral protease inhibitors, glycosylation inhibitors; those which act on a different target molecule involved in viral transmission; those which act on a different loci of the same molecule; and those which prevent or reduce the occurrence of viral resistance. One skilled in the art would know of a wide variety of antiviral therapies which exhibit the above modes of activity.

DP-178 or DP-107 or a pharmaceutically acceptable derivative thereof can also be used in combination with retrovirus inhibitors, such as nucleoside derivatives. Nucleoside derivatives are modified forms of purine and pyrimidine nucleosides which are the building blocks of RNA and DNA. Many of the nucleoside derivatives under study as potential anti-HIV medications result in premature termination of viral DNA replication before the entire genome has been transcribed. These derivatives lack 3' substituents that can bind to subsequent nucleosides and result in chain termination. Nucleoside derivatives such as 3'azido-3'-thymidine (AZT) and dideoxyinosine (ddI) have been exploited as inhibitors of HIV-1 replication, both in vitro and in vivo. Nucleoside analogs are the currently the only licensed therapeutics for the treatment of HIV infection and AIDS (Fischl et al, 1987 N. Engl. J. Med. 317, 185-191; Mitsuya and Broder, 1987 Nature 325, 773-778). This class of compounds works by inhibiting reverse transcriptase resulting in a block in cDNA synthesis (Mitsuya and Broder, 1987), these inhibitors work early in the infectious cycle of HIV-1 and inhibit integration into T-cell genome. However, AZT therapy leads to development of resistant HIV strains (Larder 1989, 1991, Ibid.) and demonstrates toxicity in AIDS patients upon long-term therapy (Fischl et al., 1987, N. Engl. J. Med. 317:185-191; Creagh-Kirk, et al., 1988, J.A.M.A. 260:3045-3048).

Further, DP-178 or DP-107 or a pharmaceutically acceptable derivative thereof can be used in combination with nucleoside derivatives which include but are not limited to, 2',3'-dideoxyadenosine (ddA); 2',3'-dideoxyguanosine (ddG); 2',3'-dideoxyinosine (ddI); 2',3'-dideoxycytidine (ddC); 2',3'-dideoxythymidine (ddT); 2',3'-dideoxy-dideoxythymidine (d4T) and 3'-azido-2',3'-dideoxythymidine (AZT). Alternatively, halogenated nucleoside derivatives may be used, preferably 2',3'-dideoxy-2'-fluoronucleosides including, but not limited to, 2',3'-dideoxy-2'-fluoroadenosine; 2',3'-dideoxy-2'-fluoroinosine; 2',3'-dideoxy-2'-fluorothymidine; 2',3'-dideoxy-2'-fluorocytosine; and 2',3'-dideoxy-2',3'-didehydro-2'-fluoronucleosides including, but not limited to 2',3'-dideoxy-2',3'-didehydro-2'-fluorothymidine (Fd4T). Preferably, the 2',3'-dideoxy-2'-fluoronucleosides of the invention are those in which the fluorine linkage is in the beta configuration, including, but not limited to, 2'3'-dideoxy-2'-beta-fluoroadenosine (F-ddA), 2',3'-dideoxy-2'-beta-fluoroinosine (F-ddI), and 2',3'-dideoxy-2'-beta-fluorocytosine (F-ddC). Such combinations allow one to use a lower dose of the nucleoside derivative thus reducing the toxicity associated with that agent, without loss of antiviral activity because of the use of the antiviral peptides. Moreover, such a combination reduces or avoids viral resistance.

Preferred combinations of antiviral peptides and nucleoside derivatives within the scope of the present invention include an effective amount of DP-107, DP-178 or a pharmaceutically acceptable derivative thereof and an effective amount of AZT to treat HIV infection; and an effective amount of DP-107, DP-178 or a pharmaceutically acceptable derivative thereof and an effective amount of ddI.

According to the present invention, DP-178 or DP-107 or a pharmaceutically acceptable derivative thereof can also be used in combination with uridine phosphorylase inhibitors, including but not limited to acyclouridine compounds, including benzylacyclouridine (BAU);

benzyloxybenzylacyclouridine (BBAU); aminomethyl-benzylacyclouridine (AMBAU); aminomethyl-benzyloxybenzylacyclouridine (AMB-BAU); hydroxymethyl-benzylacyclouridine (HMBAU); and hydroxymethyl-benzyloxybenzylacyclouridine (HMBBAU).

According to the present invention, DP-178 or DP-107 or a pharmaceutically acceptable derivative thereof can also be used in combination with cytokines or cytokine inhibitors, including but not limited to rIFN .alpha., rIFN .beta., rIFN .gamma., inhibitors of TNF.alpha., and MNX-160. Human rIFN-.alpha.A (>108 IU/mg) and rIFN .gamma. (1.4x108 IU/mg) can be obtained from Hoffman LaRoche. Human rIFN .beta. Ser 17 (1.0x108 IU/mg) are obtained from Triton Biosciences. Reference standards are obtained from the World Health Organization (human IFN.alpha. WHO standard B,69,19 and human IFN .beta., WHO no. G-023-902-527, or the National Institute of Allergy and Infectious Disease (human .gamma., National Institute of Health no. G-023-901-530.

According to the present invention, DP-178 or DP-107 or a pharmaceutically acceptable derivative thereof can be used in combination with viral protease inhibitors, including but not limited to, MK-639 (Merck), Invirase (saquinavir, Roche), ABT-538 (Abbott, CAS Reg. No. 155213-67-5), AG1343, VX0478 (Burroughs Wellcome/Glaxo, CAS Reg. No. 161814-49-9), DMP450, SC-52151 (Telinavir). Protease inhibitors are generally thought to work primarily during or after assembly (i.e., viral budding) to inhibit maturation of virions to a mature infectious state. For example, ABT-538 has been shown to have potent antiviral activity in vitro and favorable pharmokinetic and safety profiles in vivo (Ho, et al., 1995, Nature 373: 123-126). Administration of ABT-538 to AIDS patients causes plasma HIV-1 levels to decrease exponentially and CD4 lymphocyte counts to rise substantially. The exponential decline in plasma viraemia following ABT-538 treatment reflects both the clearance of free virions and the loss of HIV-1 producing cells as the drug substantially blocks new rounds of infection. ABT-538 treatment reduces virus-mediated destruction of CD4 lymphocytes. Combining this treatment with DP-178 and/or DP-107, which inhibits at an earlier stage of HIV infection, viral fusion, would be likely to have synergistic effects and have a dramatic clinical impact.

DP-178 or DP-107 or a pharmaceutically acceptable derivative thereof can also be used in combination with a class of anti-HIV drugs which interfere with 5'-mRNA processing, for example ribavirin. (Ribavirin (Virazole) from Viratel Inc.). Although the mechanism of action of ribavirin is not clear, this drug is thought to compete with guanosine in the formation of mRNA cap structures and/or interfere with the functional methylation of these molecules. These viruses which may escape the inhibition of viral fusion by DP-178 and/or DP-107 would be blocked by ribavirin and thereby exhibiting synergy of the anti-HIV mechanism of DP-178 and/or DP-107 and ribavirin.

In addition, DP-178, DP-107 or a pharmaceutically acceptable derivative thereof can be used in combination with therapeutic agents, such as Amphotericin B (Fungizone, obtained from Gibco) a polyene microlide antifungal antibiotic which interacts with sterols and binds to them irreversibly. Amphotericin B represents a unique class of agents that are active against a variety of lipid -enveloped viruses, including HIV. Although amphotericin exhibits severe in vivo toxicities, the methyl ester form of this drug also exhibits anti-HIV activity and has a low cellular toxicity profile in vitro. Therefore amphotericin B or its methyl ester can be used in combinational therapy with DP-178, DP-107 or a pharmaceutical derivative thereof. This combination allows the clinician to employ a lower i.e., less toxic dose of ether Amphotericin B or its methyl ester without concern for loss of antiviral activity since it is used in conjunction with the antiviral peptides DP-178 or DP-107.

According to the present invention, DP-178 or DP-107 or a pharmaceutically acceptable derivative thereof can also be used in combination with inhibitors of glycoprotein processing, such as castonospermine (Boehringer Mannheim). Castanospermine is a plant alkaloid which inhibits glycoprotein processing, and acts as an anti-HIV since HIV contains two heavily glycosylated proteins, gp120 and gp41. Protein glycosylation plays an important role in gp120 interaction with CD4. Under conditions of infection by progeny virions synthesized in the presence of castanospermine the infectivity of HIV was attenuated. Therefore it is likely that DP-178, DP-107 or a pharmaceutically acceptable derivative thereof in combination with castanospermine would act synergistically to inhibit viral entry and hence attenuate infection.

Preferred combinations to be used within the methods of treating HIV include the use of an effective amount of DP-107; DP-178 or a pharmaceutically acceptable derivative thereof and an effective amount of ddI; the use of an effective amount of DP-107, DP-178 or a pharmaceutically acceptable derivative thereof and an effective amount of 3TC; and the use of an effective amount of DP-107, DP-178 or a pharmaceutically acceptable derivative thereof and an effective amount ribavirin.

A further preferred combinations to be used within the methods of treating HIV include the use of an effective amount of DP-107, DP-178 or a pharmaceutically acceptable derivative thereof and an effective amount of beta-interferon.

Yet another combination to be used with the methods of treating HIV include the use of an effective amount of DP-107, DP-178 or a pharmaceutically acceptable derivative thereof and an effective amount of protease inhibitors.

In order to evaluate potential therapeutic efficacy of DP-178, DP-107 or a pharmaceutically acceptable derivative thereof in combination with the antiviral therapeutics described above, these combinations may be tested for antiviral activity according to methods known in the art. For example, the ability of a DP-178 and AZT combination to inhibit HIV cytotoxicity, syncytia formation, reverse transcriptase activity, or generation of viral RNA or proteins may be tested in vitro, as described in Example 6.

5.2.1. Therapeutic Uses of HIV-Inhibitory Combinations

The improved or synergistic DP-178 or DP-107 combination therapy as described above may be used in accordance with the invention in vivo to prevent the formation of syncytia and the production of HIV virions and, thus, inhibit the progression of HIV within an exposed patient. The combinational therapy of the present invention is also useful to alleviate or treat disease associated with HIV-infected immunosuppressed patients. For example, the antiviral peptides DP-178, DP-107 or pharmaceutically acceptable derivatives thereof may be used in combination with antifungal agents, antivirals effects against HBV, EBV, CMV, and other opportunistic infections including TB.

The antiviral peptide of the present invention, DP-178, DP-107 or pharmaceutically acceptable derivatives thereof are preferably used against HIV infection. Effective doses of the combination therapy as described below may be formulated in suitable pharmacological carriers and may be administered by any appropriate means including but not limited to injection (e.g., intravenous, intraperitoneal, intramuscular, subcutaneous, etc.), by absorption through epithelial or mucocutaneous linings (e.g., oral mucosa, rectal and vaginal epithelial linings, nasopharyngeal mucosa, intestinal mucosa, etc.); orally, transdermally or any other means available within the pharmaceutical arts.

5.3. Pharmaceutical Formulations, Dosages and Modes of Administration

5.3.1. Pharmaceutical Compositions

The pharmaceutical compositions of the invention which are useful in the treatment or prevention of viral infections in humans contain as an active agent DP-178, DP-107 or a pharmaceutically acceptable derivative thereof, and at least one other therapeutic agent, such as another antiviral. The pharmaceutical compositions of the present invention provide combinational therapy that may have either additive and/or synergistic effects.

Preferably, the pharmaceutical compositions containing DP-178 or DP-107 or a pharmaceutically acceptable derivative thereof also contain at least one other antiviral agent, such as reverse transcriptase inhibitors, protease inhibitor, inhibitors of mRNA processing, inhibitors of protein glycosylation and inhibitors of viral fusion. Such agents include but are not limited to nucleoside analogs or chain terminators (e.g., dideoxynucleosides).

Additional suitable therapeutic agents which may be used in combinational therapy with DP-178 or DP-107 or a pharmaceutically acceptable derivative thereof within the scope of the invention include but are not limited to 2-deoxy-D-glucose (2-dGlc), deoxynojirimycin, acycloguanosine, ribavirin (virazole), rifampicin (rifadin), adamantidine, rifabutine, ganciclover, (DHPG), fluoroiodoaracytosine, idoxurine, trifluorothymidine, adenine arabinoside (ara-A), ara-AMP, bromovinyldeoxyuridine, bromovinylarauracil (BV-araU by Bristol-Meyers Squibb (1-beta-D-arabinofuranoside-E-5-[2-bromovinyl]uracil)) rimantadine, arildone, diarylamidine, (S)-(p-nitrobenzyl-)6-thioinosine and phosphonoformate.

Novel pharmaceutical compositions encompassed by the present invention include but are not limited to DP-178, DP-107 or a pharmaceutically acceptable derivative, and rifampicin (rifadin); DP-178 or DP-107 and AZT; DP-178 or DP-107 and ddI; DP-178 or DP-107 and ddC; DP-178 or DP-107 and adamantidine; DP-178 or DP-107 and acycloguanosine; DP-178 or DP-107 and 2-deoxy-D-glucose; DP-178 or DP-107 and deoxynojirimycin; DP-178 or DP-107 and interferon-.alpha. and DP-178 or DP-107 and ganciclovir. The present invention also encompasses pharmaceutical compositions which contain DP-178 or DP-107, or a pharmaceutically acceptable derivative, and optionally more than one additional therapeutic compound.

The peptides of the invention may be administered using techniques well known to those in the art. Preferably, agents are formulated and administered systemically. Techniques for formulation and administration may be found in "Remington's Pharmaceutical Sciences", 18th ed., 1990, Mack Publishing Co., Easton, Pa. Suitable routes may include oral, rectal, transmucosal, or intestinal administration; parenteral delivery, including intramuscular, subcutaneous, intramedullary injections, as well as intrathecal, direct intraventricular, intravenous, intraperitoneal, intranasal, or intraocular injections, just to name a few. Most preferably, administration is intravenous. For injection, the agents of the invention may be formulated in aqueous solutions, preferably in physiologically compatible buffers such as Hanks' solution, Ringer's solution, or physiological saline buffer. For such transmucosal administration, penetrants appropriate to the barrier to be permeated are used in the formulation. Such penetrants are generally known in the art.

In addition, the peptides may be used as a prophylactic measure in previously uninfected individuals after acute exposure to an HIV virus. Examples of such prophylactic use of the peptides may include, but are not limited to, prevention of virus transmission from mother to infant and other settings where the likelihood of HIV transmission exists, such as, for example, accidents in health care settings wherein workers are exposed to HIV-containing blood products. The peptides of the invention in such cases may serve the role of a prophylactic vaccine, wherein the host raises antibodies against the peptides of the invention, which then serve to neutralize HIV viruses by, for example, inhibiting further HIV infection. Administration of the peptides of the invention as a prophylactic vaccine, therefore, would comprise administering to a host a concentration of peptides effective in raising an immune response which is sufficient to neutralize HIV, by, for example, inhibiting HIV ability to infect cells. The exact concentration will depend upon the specific peptide to be administered, but may be determined by using standard techniques for assaying the development of an immune response which are well known to those of ordinary skill in the art. The peptides to be used as vaccines are usually administered intramuscularly.

The peptides may be formulated with a suitable adjuvant in order to enhance the immunological response. Such adjuvants may include, but are not limited to mineral gels such as aluminum hydroxide; surface active substances such as lysolecithin, pluronic polyols, polyanions; other peptides; oil emulsions; and potentially useful human adjuvants such as BCG and Corynebacterium parvum. Many methods may be used to introduce the vaccine formulations described here. These methods include but are not limited to oral, intradermal, intramuscular, intraperitoneal, intravenous, subcutaneous, and intranasal routes.

Effective dosages of the peptides of the invention to be administered may be determined through procedures well known to those in the art which address such parameters as biological half-life, bioavailability, and toxicity. Given the data presented below in Section 6, DP-178, for example, may prove efficacious in vivo at doses required achieve circulating levels of 10 ng per ml of peptide.

5.3.2. Dosage

In treating mammals, including humans, having a viral infection a therapeutically effective amount of DP-178, DP-107 or a pharmaceutically acceptable derivative is administered, i.e., a dose sufficient to inhibit viral replication. For example DP-178 or DP-107 may be administered as an infusion at about 0.1 mg/kg to 1.0 mg/kg per day for about 12 weeks. A preferable dose is from 20 mg to 35 mg; the equivalent daily dose of DP-178 or DP-107 or a pharmaceutically acceptable derivative thereof based on surface area is from about 7 mg to 70 mg. The most preferred dose is about 20 mg to 35 mg for about 12 weeks. Doses of DP-178, DP-107 or a pharmaceutically acceptable derivative should be administered in intervals of from about once per day to 4 times per day and preferably from about once every two days to once per day. A preferred dose is administered to achieve peak plasma concentrations of DP-178, DP-107 or a pharmaceutically acceptable derivative thereof from about 1 mg/ml to 10 mg/ml. This may be achieved by the sterile injection of a 2.0% solution of the administered ingredients in buffered saline (any suitable saline solutions known to those skilled in the art of chemistry may be used). Desirable blood levels may be maintained by a continuous infusion of DP-178 or DP-107 as ascertained by plasma levels measured by HPLC.

Effective amounts of the therapeutic agents, e.g., antivirals to be used in combination with DP-178, DP-107 or a pharmaceutically acceptable derivative thereof are based on the recommended doses known to those skilled in the art for the various antivirals. For example, doses for AZT, ddI and interferon-Beta can be found in standard physician reference texts. In addition, doses for other therapeutic agents, including antivirals, are reported in the literature, for example, ABT-538 is administered orally 600-1,200 mg/day on day 1 and daily thereafter (Ho, et al., 1995, Nature 373: 123-126). These recommended or known levels will preferably be lowered by 10% to 50% of the cited dosage after testing the effectiveness of these dosages in combination with DP-178, DP-107 or a pharmaceutically acceptable derivative, using the assays described in Section 5.4 infra. It should be noted that the attending physician would know how to and when to terminate, interrupt, or adjust therapy to lower dosage due to toxicity, bone marrow, liver or kidney dysfunctions or adverse drug-drug interaction. Conversely, the attending physician would also know to adjust treatment to higher levels if the clinical response is not adequate (precluding toxicity).

A therapeutically effective dose refers to that amount of the compound sufficient to result in amelioration of symptoms or a prolongation of survival in a patient. Toxicity and therapeutic efficacy of such compounds can be determined by standard pharmaceutical procedures in cell cultures or experimental animals, e.g., for determining the LD50 (the dose lethal to 50% of the population) and the ED50 (the dose therapeutically effective in 50% of the population). The dose ratio between toxic and therapeutic effects is the therapeutic index and it can be expressed as the ratio LD50/ED50. Compounds which exhibit large therapeutic indices are preferred. The data obtained from these cell culture assays and animal studies can be used in formulating a range of dosage for use in humans. The dosage of such compounds lies preferably within a range of circulating concentrations that include the ED50 with little or no toxicity. The dosage may vary within this range depending upon the dosage form employed and the route of administration utilized. For any compound used in the method of the invention, the therapeutically effective dose can be estimated initially from cell culture assays. A dose may be formulated in animal models to achieve a circulating plasma concentration range that includes the IC50 (i.e., the concentration of the test compound which achieves a half-maximal inhibition of RT production from infected cells compared to untreated control as determined in cell culture. Such information can be used to more accurately determine useful doses in humans. Levels in plasma may be measured, for example, by high performance liquid chromatography (HPLC).

5.4. Pharmaceutical Formulations and Routes of Administration

Pharmaceutical compositions containing DP-178, DP-107 or a pharmaceutically acceptable derivative can be administered to a human patient, by itself, or in pharmaceutical compositions where it is mixed with suitable carriers or excipient(s) at doses to treat a viral infection, in particular HIV infection. Techniques for formulation and administration of the compounds of the instant application may be found in "Remington's Pharmaceutical Sciences," Mack Publishing Co., Easton, Pa., latest edition.

As demonstrated in the Example presented below in Section 6, the antiviral activity of the peptides of the invention may show a pronounced type and subtype specificity, i.e., specific peptides may be effective in inhibiting the activity of only specific viruses. This feature of the invention presents many advantages. One such advantage, for example, lies in the field of diagnostics, wherein one can use the antiviral specificity of the peptide of the invention to ascertain the identity of a viral isolate. With respect to HIV, one may easily determine whether a viral isolate consists of an HIV-1 or HIV-2 strain. For example, uninfected CD-4⁺ cells may be co-infected with an isolate which has been identified as containing HIV the DP-178 (SEQ ID:1) peptide, after which the retroviral activity of cell supernatants may be assayed, using, for example, the techniques described above in Section 5.2. Those isolates whose retroviral activity is completely or nearly completely inhibited contain HIV-1. Those isolates whose viral activity is unchanged or only reduced by a small amount, may be considered to not contain HIV-1. Such an isolate may then be treated with one or more of the other DP-178 peptides of the invention, and subsequently be tested for its viral activity in order to determine the identify of the viral isolate.

Use of pharmaceutically acceptable carriers to formulate the compounds herein disclosed for the practice of the invention into dosages suitable for systemic administration is within the scope of the invention. With proper choice of carrier and suitable manufacturing practice, the compositions of the present invention, in particular, those formulated as solutions, may be administered parenterally, such as by intravenous injection. The compounds can be formulated readily using pharmaceutically acceptable carriers well known in the art into dosages suitable for oral administration. Such carriers enable the compounds of the invention to be formulated as tablets, pills, capsules, liquids, gels, syrups, slurries, suspensions and the like, for oral ingestion by a patient to be treated.

Suitable routes of administration may, for example, include oral, rectal, transmucosal, or intestinal administration; parenteral delivery, including intramuscular, subcutaneous, intramedullary injections, as well as intrathecal, direct intraventricular, intravenous, intraperitoneal, intranasal, or intraocular injections; transdermal, topical, vaginal and the like. Dosage forms include but are not limited to tablets, troches, dispersions, suspensions, suppositories, solutions, capsules, creams, patches, minipumps and the like.

Pharmaceutical compositions for use in accordance with the present invention thus may be formulated in conventional manner using one or more physiologically acceptable carriers comprising excipients and auxiliaries which facilitate processing of the active compounds into preparations which can be used pharmaceutically. Proper formulation is dependent upon the route of administration chosen.

For injection, the agents of the invention may be formulated in aqueous solutions, preferably in physiologically compatible buffers such as Hanks's solution, Ringer's solution, or physiological saline buffer. For transmucosal administration, penetrants appropriate to the barrier to be permeated are used in the formulation. Such penetrants are generally known in the art.

For oral administration, the compounds can be formulated readily by combining the active compounds with pharmaceutically acceptable carriers well known in the art. Such carriers enable the compounds of the invention to be formulated as tablets, pills, dragees, capsules, liquids, gels, syrups, slurries, suspensions and the like, for oral ingestion by a patient to be treated. Pharmaceutical preparations for oral use can be obtained solid excipient, optionally grinding a resulting mixture, and processing the mixture of granules, after adding suitable auxiliaries, if desired, to obtain tablets or dragee cores. Suitable excipients are, in particular, fillers such as sugars, including lactose, sucrose, mannitol, or sorbitol; cellulose preparations such as, for example, maize starch, wheat starch, rice starch, potato starch, gelatin, gum tragacanth, methyl cellulose, hydroxypropylmethyl-cellulose, sodium carboxymethylcellulose, and/or polyvinylpyrrolidone (PVP). If desired, disintegrating agents may be added, such as the cross-linked polyvinyl pyrrolidone, agar, or alginic acid or a salt thereof such as sodium alginate.

Dragee cores are provided with suitable coatings. For this purpose, concentrated sugar solutions may be used, which may optionally contain gum arabic, talc, polyvinyl pyrrolidone, carbopol gel, polyethylene glycol, and/or titanium dioxide, lacquer solutions, and suitable organic solvents or solvent mixtures. Dyestuffs or pigments may be added to the tablets or dragee coatings for identification or to characterize different combinations of active compound doses.

Pharmaceutical preparations which can be used orally include push-fit capsules made of gelatin, as well as soft, sealed capsules made of gelatin and a plasticizer, such as glycerol or sorbitol. The push-fit capsules can contain the active ingredients in admixture with filler such as lactose, binders such as starches, and/or lubricants such as talc or magnesium stearate and, optionally, stabilizers. In soft capsules, the active compounds may be dissolved or suspended in suitable liquids, such as fatty oils, liquid paraffin, or liquid polyethylene glycols. In addition, stabilizers may be added. All formulations for oral administration should be in dosages suitable for such administration.

For buccal administration, the compositions may take the form of tablets or lozenges formulated in conventional manner.

For administration by inhalation, the compounds for use according to the present invention are conveniently delivered in the form of an aerosol spray presentation from pressurized packs or a nebulizer, with the use of a suitable propellant, e.g., dichlorodifluoromethane, trichlorofluoromethane, dichlorotetrafluoroethane, carbon dioxide or other suitable gas. In the case of a pressurized aerosol the dosage unit may be determined by providing a valve to deliver a metered amount. Capsules and cartridges of e.g. gelatin for use in an inhaler or insufflator may be formulated containing a powder mix of the compound and a suitable powder base such as lactose or starch.

The compounds may be formulated for parenteral administration by injection, e.g., by bolus injection or continuous infusion. Formulations for injection may be presented in unit dosage form, e.g., in ampoules or in multi-dose containers, with an added preservative. The compositions may take such forms as suspensions, solutions or emulsions in oily or aqueous vehicles, and may contain formulatory agents such as suspending, stabilizing and/or dispersing agents.

Pharmaceutical formulations for parenteral administration include aqueous solutions of the active compounds in water-soluble form. Additionally, suspensions of the active compounds may be prepared as appropriate oily injection suspensions. Suitable lipophilic solvents or vehicles include fatty oils such as sesame oil, or synthetic fatty acid esters, such as ethyl oleate or triglycerides, or liposomes. Aqueous injection suspensions may contain substances which increase the viscosity of the suspension, such as sodium carboxymethyl cellulose, sorbitol, or dextran. Optionally, the suspension may also contain suitable stabilizers or agents which increase the solubility of the compounds to allow for the preparation of highly concentrated solutions.

Alternatively, the active ingredient may be in powder form for constitution with a suitable vehicle, e.g., sterile pyrogen-free water, before use.

The compounds may also be formulated in rectal compositions such as suppositories or retention enemas, e.g., containing conventional suppository bases such as cocoa butter or other glycerides.

In addition to the formulations described previously, the compounds may also be formulated as a depot preparation. Such long acting formulations may be administered by implantation (for example subcutaneously or intramuscularly) or by intramuscular injection. Thus, for example, the compounds may be formulated with suitable polymeric or hydrophobic materials (for example as an emulsion in an acceptable oil) or ion exchange resins, or as sparingly soluble derivatives, for example, as a sparingly soluble salt.

A pharmaceutical carrier for the hydrophobic compounds of the invention is a cosolvent system comprising benzyl alcohol, a nonpolar surfactant, a water-miscible organic polymer, and an aqueous phase. The cosolvent system may be the VPD co-solvent system. VPD is a solution of 3% w/v benzyl alcohol, 8% w/v of the nonpolar surfactant polysorbate 80, and 65% w/v polyethylene glycol 300, made up to volume in absolute ethanol. The VPD co-solvent system (VPD:5W) consists of VPD diluted 1:1 with a 5% dextrose in water solution. This co-solvent system dissolves hydrophobic compounds well, and itself produces low toxicity upon systemic administration. Naturally, the proportions of a co-solvent system may be varied considerably without destroying its solubility and toxicity characteristics. Furthermore, the identity of the co-solvent components may be varied: for example, other low-toxicity nonpolar surfactants may be used instead of polysorbate 80; the fraction size of polyethylene glycol may be varied; other biocompatible polymers may replace polyethylene glycol, e.g. polyvinyl pyrrolidone; and other sugars or polysaccharides may substitute for dextrose.

The pharmaceutical compositions also may comprise suitable solid or gel phase carriers or excipients. Examples of such carriers or excipients include but are not limited to calcium carbonate, calcium phosphate, various sugars, starches, cellulose derivatives, gelatin, and polymers such as polyethylene glycols. Pharmaceutical compositions suitable for use in the present invention include compositions wherein the active ingredients are contained in an effective amount to achieve its intended purpose. Determination of the effective amounts is well within the capability of those skilled in the art, especially in light of the detailed disclosure provided herein.

5.5. Assays for Antiviral Activity

The antiviral activity exhibited by the combination therapy of the invention may be measured, for example, by easily performed in vitro assays, such as those described below, which can test the peptides' ability to inhibit syncytia formation, or their ability to inhibit infection by cell-free virus. Using these assays, such parameters as the relative antiviral activity of the peptides, exhibit against a given strain of virus and/or the strain specific inhibitory activity of the peptide can be determined. A cell fusion assay may be utilized to test the peptides, ability to inhibit HIV-induced syncytia formation in vitro. Such an assay may comprise culturing uninfected CD-4+ cells (such as Molt or CEM cells, for example) in the presence of chronically HIV-infected cells and a therapeutic agent to be assayed. For each combinational therapy, a range of concentrations may be tested. This range should include a control culture wherein no peptide has been added. Standard conditions for culturing, well known to those of ordinary skill in the art, are used. After incubation for an appropriate period (24 hours at 37^oC., for example) the culture is examined microscopically for the presence of multinucleated giant cells, which are indicative of cell fusion and syncytia formation.

A reverse transcriptase (RT) assay may be utilized to test the peptides' ability to inhibit infection of CD-4⁺ cells by cell-free HIV in combination with another antiviral agent. Such an assay may comprise culturing an appropriate concentration (i.e., TCID₅₀) of virus and CD-4⁺ cells in the presence of the peptide and the antiviral in combination to be tested. Culture conditions well known to those in the art are used. As above, a range of peptide concentrations may be used, in addition to a control culture wherein no peptide has been added. After incubation for an appropriate period (e.g., 7 days) of culturing, a cell-free supernatant is prepared, using standard procedures, and tested for the present of RT activity as a measure of successful infection. The RT activity may be tested using standard techniques such as those described by, for example, Goff et al. (Goff, S. et al., 1981, J. Virol. 38:239-248) and/or Willey et al. (Willey, R. et al., 1988, J. Virol. 62:139-147). These references are incorporated herein by reference in their entirety.

Standard methods which are well-known to those of skill in the art may be utilized for assaying non-retroviral activity. See, for example, Pringle et al. (Pringle, C. R. et al., 1985, J. Medical Virology 17:377-386) for a discussion of respiratory syncytial virus and parainfluenza virus activity assay techniques. Further, see, for example, "Zinsser Microbiology", 1988, Joklik, W. K. et al., eds., Appleton & Lange, Norwalk, Conn., 19th ed., for a general review of such techniques. These references are incorporated by reference herein in its entirety.

5.5.1. Testing of Antiviral Compounds Active at Different Stares of HIV-1 Infection

Three separate in vitro assays for the study of antiviral compounds active at different stages of HIV infection (acute, co-cultivation, and chronic) are well known to those skilled in the art (Lambert et al., 1993, Antiviral Res. 21: 327-342). These assays can be used to assess the effects of DP-178, DP-107 or a pharmaceutically acceptable derivative thereof in combination with one of the described antiviral agents. All assays are carried out in triplicate in 24-well plates (Nunc.) 5-fold serial dilutions of inhibitor are made in 100% DMSO to yield 200x final concentrations. Addition of 1/200 vol. of dilutions to culture wells resulted in a final concentration of 0.5% DMSO and the desired concentration of the inhibitor. Experiments are carried out either with dilutions of fixed ratio of the two inhibitors (i.e., 1:10 or 1:40, AZT:DP-178) or where the concentrations are varied.

First the acute infection assay models the rapid replication and cytopathic effects contributing to the loss of CD-4+ cells in vivo. Assay the treatment of acutely infected Molt4 cells to show the antiviral compounds are effective at inhibiting the spread of HIV-1 infection in T cells. For these assays, 3x10⁴ uninfected Molt4 cells per well are infected with 50 TCIDs of HIV-1 (strain LA1). Stocks of inhibitors are prepared in 100% DMSO, and added on day 0, immediately after the 1.5 hour virus absorption period. Cultures are re-fed on days 1 and 4 with medium containing the same concentration of inhibitor. Samples are harvested on day 7.

Second, chronically infected cells, containing integrated provirus and exhibiting moderate to low levels of continuous virus expression, are likely to represent in vivo reservoirs of infectious virions, which ultimately contribute to disease progression. Chronically infected cells are washed three times in growth medium and plated at density 6x10⁴ cells per well. Inhibitors are added on day 0. Cultures are re-fed on days 1 and 3 with growth medium containing the same concentration of inhibitor. Assays are harvested on day 5.

Third, the co-cultivation assay used in these studies is a relevant model of in vivo infection since it involves cell to cell fusion and spread as well as cell free spread of HIV-1 within the culture. For this assay, 3x10⁴ uninfected Molt4 cells are cocultivated with 3x10³ H9/LA1 or CEM/LA1 chronically infected cells per well in 24 well plates. Inhibitors are added on day 0, and the assay plates are re-fed on days 1 and 3 with growth medium containing the inhibitors. The assay is harvested on day 5. Antiviral activity is measured by several parameters: Western blot analysis of pelleted cells from treated cultures, RT levels, and p24 antigen levels in the supernatant.

The combined drug effects are calculated by the multiple drug analysis method of Chou and Talalay (Chou and Talalay, 1984, Adv. Enzyme Regul. 22:27-55) and `Dose-Effect Analysis with Microcomputers` software (Chou and Chou, 1987, software and manual. p19-64. Elsevier Biosoft, Cambridge, UK) using the equation: ##EQU1##

where CI is the combination index, (Dx)₁ is the dose of drug 1 required to produce x percent effect alone, (D)₁ is the dose of drug 1 required to produce the same x percent effect in combination with (D)₂. The values of (Dx)₂ and (D)₂ are similarly derived from drug 2. The value of .alpha. is determined from the plot of the dose effect curve using the median effect equation:

fa/fu=(D/Dm)^m

where fa is the fraction affected by dose D, fu is the uninfected fraction, Dm is the dose required for 50% effect and m is the slope of the dose-effect curve. For mutually exclusive drugs (i.e. similar modes of action), both drugs alone and their parallel lines in the median effect plot. Mutually nonexclusive drugs (i.E. independent mode of action) will give parallel lines in the median effect plot, but in mixture will give a concave upward curve. If the agents are mutually exclusive .alpha. is 0, and if they are mutually nonexclusive, .alpha. is 1. Values obtained assuming mutual nonexclusiveness will always be slightly greater than mutually exclusive drugs. CI values of <1 indicate synergy, values >1 indicate antagonism and values equal to 1 indicate additive effects.

The combined drug effects are also calculated by the MacSynergy computer program (Pritchard and Shipman, 1990, Antiviral Research 14: 181-206). This computer program allows three-dimensional graphic analysis of drug-drug interactions. The amount of synergy observed with combinations of antiviral compounds is calculated by the MacSynergy program and is represented by a three-dimensional bar graph in which the percentage of drug interaction is plotted versus drug concentrations. The amount of synergy is represented by the heights of bars in the graph and antagonism is plotted as a negative value below the floor of the graph.

Claim 1 of 113 Claims

What is claimed is:

1. A method of treating HIV-1 infection in a subject, comprising administering to the subject a therapeutically effective amount of DP-178 having SEQ ID NO:1, or a pharmaceutically acceptable derivative thereof, and a therapeutically effective amount of at least one other therapeutic agent which is a viral entry inhibitor, reverse transcriptase inhibitors or an inhibitor of HIV-1 protease.

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