Therapeutic inhibitor of vascular smooth muscle cells

Abstract

Methods are provided for inhibiting or treating stenosis or restenosis following vascular trauma or disease in a mammalian host, comprising administering to the host a therapeutically effective amount of a therapeutic agent via a catheter. Also provided is a catheter adapted for administering a therapeutically effective amount of a therapeutic agent to a mammalian host for inhibiting or treating stenosis or restenosis.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS[0001]This application is a continuation of U.S. patent application Ser. No. 09 / 910,388, filed Jul. 20, 2001, which is a continuation of U.S. patent application Ser. No. 09 / 470,662, filed Dec. 22, 1999, now U.S. Pat. No. 6,268,390, which is a continuation of U.S. patent application Ser. No. 09 / 113,733, filed Jul. 10, 1998, now U.S. Pat. No. 6,074,659, which is a continuation of U.S. patent application Ser. No. 08 / 450,793, filed May 25, 1995, now U.S. Pat. No. 5,811,447, which is a continuation of U.S. patent application Ser. No. 08 / 062,451, filed May 13, 1993, abandoned, which is a continuation-in-part of U.S. patent application Ser. No. 08 / 011,669, filed Jan. 28, 1993, abandoned, filed the entire disclosure of each of which is incorporated herein by reference in its entirety.FIELD OF THE INVENTION[0002]This invention relates generally to therapeutic methods involving surgical or intravenous introduction of binding partners directed to certain ...

AI Technical Summary

Benefits of technology

[0010]Other aspects of the invention include methods for inhibiting stenosis, e.g., following angioplasty in a mammalian host, by administering to a human or animal subject in need of such treatment a therapeutically effective dosage of a therapeutic conjugate of the invention. In one representative embodiment, the dosage of therapeutic conjugate may be administered with an infusion catheter, to achieve a 10−3 M to 10−12 M concentration of said therapeutic conjugate at the site of administration in a blood vessel.

[0011]The present invention also contemplates therapeutic methods and therapeutic dosage forms involving sustained release of therapeutic agent to target cells. Preferably, the target cells are vascular smooth muscle cells, cancer cells, somatic cells requiring modulation to ameliorate a disease state and cells involved in immune system-mediated diseases that are accessible by local administration of the dosage form. Consequently, the methods and dosage forms of this aspect of the present invention are useful for inhibiting vascular smooth muscle cells in a mammalian host, employing a therapeutic agent that inhibits the activity of the cell (e.g., proliferation, contraction, migration or the like) but does not kill the cell and, optionally, a vascular smooth muscle cell binding protein. Also, the methods and dosage forms of this aspect of the present invention are useful for inhibiting target cell proliferation or killing such target cells, employing a therapeutic agent that inhibits proliferation or is cytotoxic to the target cells and, optionally, a target cell binding protein. In addition, the methods and dosage forms of this aspect of the present invention are useful for delivering cytostatic, cytocidal or metabolism modulating therapeutic agents to target cells, such as effector cells of the immune system, that are accessible by local administration of the dosage form, optionally employing a target cell binding protein. Finally, dosage forms of the present invention are useful to reduce or eliminate pathological proliferation or hyperactivity of normal tissue (i.e., somatic cells).

[0012]The dosage forms of the present invention are preferably either non-degradable microparticulates or nanoparticulates or biodegradable microparticulates or nanoparticulates. More preferably, the microparticles or nanoparticles are formed of a polymer containing matrix that biodegrades by random, nonenzymatic, hydrolytic scissioning. A particularly preferred structure is formed of a mixture of thermoplastic polyesters (e.g., polylactide or polyglycolide) or a copolymer of lactide and glycolide components. The lactide / glycolide structure has the added advantage that biodegradation thereof forms lactic acid and glycolic acid, both normal metabolic products of mammals.

[0013]Preferable therapeutic agents dispersed within the microparticulates or nanoparticulates are those exhibiting inhibition of a therapeutically significant target cell activity without killing the target cell, or target cell killing activity. For treatment of restenosis of vascular smooth muscle cells, useful therapeutic agents inhibit target cell activity (e.g., proliferation or migration) without killing the target cells. Preferred therapeutic moieties for this purpose are protein kinase inhibitors (e.g., staurosporin or the like), TGF-beta production or activation stimulators, such as tamoxifen or TGF-beta itself, taxol or analogs thereof (e.g., taxotere), smooth muscle migration and / or contraction inhibitors (e.g., the cytochalasins, such as cytochalasin B, cytochalasin C, cytochalasin D or the like), suramin, and nitric oxide-releasing compounds, such as nitroglycerin, or analogs or functional equivalents thereof. In cancer therapy, useful therapeutic agents inhibit proliferation or are cytotoxic to the target cells. Preferred therapeutic moieties for this purpose are TGF-beta production or activation stimulators, such as tamoxifen or TGF-beta itself, taxol or analogs thereof (e.g., taxotere), Roridin A and Pseudomonas exotoxin, or analogs or functional equivalents thereof. For treatment of immune system-modulated diseases, such as arthritis, useful therapeutic agents deliver cytostatic, cytocidal or metabolism-modulating therapeutic agents to target cells that are accessible by local administration of the dosage form. Preferred therapeutic moieties for this purpose are Roridin A, Pseudomonas exotoxin, suramin, TGF-beta production or activation stimulators, such as tamoxifen or TGF-beta itself, taxol or analogs thereof (e.g., taxotere) and protein kinase inhibitors (e.g., staurosporin), sphingosine, or analogs or functional equivalents thereof. For treatment of pathologically proliferating normal tissues (e.g., proliferative vitreoretinopathy, corneal pannus and the like), anti-proliferative agents or antimigration agents are preferred (e.g., cytochalasins, taxol or analogs thereof, somatostatin, somatostatin analogs, N-ethylmaleimide, antisense oligonucleotides, TGF-beta production or activation stimulators, such as tamoxifen or TGF-beta itself and the like).

[0014]The dosage forms of the present invention are optionally targeted to a relevant target cell population by a binding protein or peptide. Preferred binding proteins / peptides of the present invention are vascular smooth muscle cell binding protein, tumor cell binding protein and immune system effector cell binding protein. Preferred vascular smooth muscle cell binding proteins specifically associate with a chondroitin sulfate proteoglycan (CSPG) expressed on the membranes of a vascular smooth muscle cell, and in a preferred embodiment this CSPG has a molecular weight of about 250 kDaltons. In preferred embodiments, the vascular smooth muscle binding protein binds to a CSPG target on the cell surface with an association constant of at least 10−4 M. In other preferred embodiments, the vascular smooth muscle binding protein contains a sequence of amino acids found in the Fab, Fv or CDR (complementarity determining regions) of monoclonal antibody NR-AN-01 or functional equivalents thereof. Other preferred binding peptides useful in this embodiment of the present invention include those that localize to intercellular stroma and matrix located between and among vascular smooth muscle cells. Preferred binding peptides of this type are specifically associated with collagen, reticulum fibers or other intercellular matrix compounds. Preferred tumor cell binding proteins are associated with surface cell markers expressed by the target tumor cell population or cytoplasmic epitopes thereof. Preferred immune system-modulated target cell binding proteins are associated with cell surface markers of the target immune system effector cells or cytoplasmic epitopes thereof. Binding peptides / proteins of the present invention also target pathologically proliferating normal tissues.

[0015]The present invention also provides therapeutic methods and therapeutic dosage forms involving administration of free (i.e., non-targeted or non-binding partner associated) therapeutic agent to target cells. Preferably, the target cells are vascular smooth muscle cells and the therapeutic agent is an inhibitor of vascular smooth muscle cell contraction, allowing the normal hydrostatic pressure to dilate the vascular lumen. Such contraction inhibition may be achieved by actin inhibition, which is preferably achievable and sustainable at a lower dose level than that necessary to inhibit protein synthesis. Consequently, the vascular smooth muscle cells synthesize protein required to repair minor cell trauma and secrete interstitial matrix, thereby facilitating the fixation of the vascular lumen in a dilated state near its maximal systolic diameter. This phenomenon constitutes a biological stenting effect that diminishes or prevents the undesirable recoil mechanism that occurs in up to 25% of the angioplasty procedures classified as successful based on an initial post-procedural angiogram. Cytochalasins (which inhibit the polymerization of G- to F-actin which, in turn, inhibits the migration and contraction of vascular smooth muscle cells) are the preferred therapeutic agents for use in this embodiment of the present invention. Free therapeutic agent protocols of this type effect a reduction, a delay, or an elimination of stenosis after angioplasty or other vascular surgical procedures. Preferably, free therapeutic agent is administered directly or substantially directly to vascular smooth muscle tissue. Such administration is preferably effected by an infusion catheter, to achieve a 10−3 M to 10−12 M concentration of said therapeutic agent at the site of administration in a blood vessel.

Problems solved by technology

Stenosis following PTCA remains a significant problem, with from 25% to 35% of the patients developing restenosis within 1 to 3 months.

Restenosis results in significant morbidity and mortality and frequently necessitates further interventions such as repeat angioplasty or coronary bypass surgery.

No surgical intervention or post-surgical treatment (to date) has proven effective in preventing restenosis.

The processes responsible for stenosis after PTCA are not completely understood but may result from a complex interplay among several different biologic agents and pathways.

Compounds that reportedly suppress smooth muscle proliferation in vitro (4, 6, 7) may have undesirable pharmacological side effects when used in vivo.

Heparin is an example of one such compound, which reportedly inhibits smooth muscle cell proliferation in vitro but when used in vivo has the potential adverse side effect of inhibiting coagulation.

Heparin peptides, while having reduced anti-coagulant activity, have the undesirable pharmacological property of having a short pharmacological half-life.

First, inhibitory agents may have systemic toxicity that could create an unacceptable level of risk for patients with cardiovascular disease.

Second, inhibitory agents might interfere with vascular wound healing following surgery and that could either delay healing or weaken the structure or elasticity of the newly healed vessel wall.

Third, inhibitory agents killing smooth muscle cells could damage surrounding endothelium and / or other medial smooth muscle cells.

Fourth, delivery of therapeutically effective levels of an inhibitory agent may be problematic from several standpoints: namely, a) delivery of a large number of molecules into the intercellular spaces between smooth muscle cells may be necessary, i.e., to establish favorable conditions for allowing a therapeutically effective dose of molecules to cross the cell membrane; b) directing an inhibitory drug into the proper intracellular compartment, i.e., where its action is exerted, may be difficult to control; and, c) optimizing the association of the inhibitory drug with its intracellular target, e.g., a ribosome, while minimizing intercellular redistribution of the drug, e.g. to neighboring cells, may be difficult.

As is apparent from the foregoing, many problems remain to be solved in the use of inhibitory drugs, including cytotoxic agents, to effectively treat smooth muscle cell proliferation.

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