Patent Application
20110021618
Pathological fibrosis is described by an aberrant expansion, firming, and/or scarring of tissue. It is characterized by an excess deposition of extracellular matrix components including collagen. Fibrosis typically results from a state of chronic inflammation in which inflammation, tissue remodeling and repair processes occur simultaneously. Despite having distinct etiological and clinical manifestations, most chronic fibrotic disorders have in common a persistent irritant or stimuli including persistent infections, autoimmune reactions, allergic responses, chemical insults, radiation, and tissue injury. The irritant or stimuli sustains the production of growth factors, proteolytic enzymes, angiogenic factors and fibrogenic cytokines, which stimulate the deposition of connective tissue elements that progressively remodel and destroy normal tissue architecture. In some diseases, such as idiopathic pulmonary fibrosis, liver cirrhosis, cardiovascular fibrosis, systemic sclerosis and nephritis, extensive tissue remodeling and fibrosis can ultimately lead to organ failure and death.
The present invention relates to compositions and methods for treating fibrotic disorders. The current invention is directed in part to benzo[c]chromen-6-one compounds and pharmaceutical compositions thereof that demonstrate a therapeutic benefit in diseases involving fibrosis.
In yet another embodiment, the present invention is directed toward methods of administering a therapeutically effective amount of one or more compositions described herein to a subject in need thereof. In one aspect, the targeted subject has been diagnosed with a fibrotic disorder.
Other features and advantages of the invention will be apparent from the following detailed description of embodiments thereof.
Most chronic fibrotic disorders have in common a persistent irritant or stimuli including persistent infections, autoimmune reactions, allergic responses, chemical insults, radiation, and tissue injury. The irritant or stimuli sustains the production of growth factors, proteolytic enzymes, angiogenic factors and fibrogenic cytokines, which stimulate the deposition of connective tissue components that replace normal parenchymal tissue. In some diseases, such as idiopathic pulmonary fibrosis, liver cirrhosis, cardiovascular fibrosis, systemic sclerosis and nephritis, extensive tissue remodelling and fibrosis can ultimately lead to organ failure and death (Table 1). Wynn, T A, “Cellular and Molecular Mechanisms of Fibrosis”, J Pathol, 214:199-210 (2008).
In this invention we describe examples of fibrosis that involve the eye and the lung with the understanding that the induction of fibrosis occurs through a series of events in a similar manner in a variety of tissues. We claim that benzo[c]chromen-6-one compounds and pharmaceutical compositions thereof demonstrate a therapeutic benefit in diseases involving fibrosis. We further claim that inhibition of the Akt/mTOR signal transduction pathway by benzo[c]chromen-6-one compounds and pharmaceutical compositions thereof demonstrate a therapeutic benefit in diseases involving fibrosis.
The present invention relates to compositions and methods for preventing and/or treating diseases associated with fibrosis. The current invention is directed in part to a series of chemical compositions that demonstrate therapeutic benefit in fibrotic diseases. In a particular aspect, the instant invention relates to benzo[c]chromen-6-one derivatives that demonstrate their effect on fibrotic diseases.
The term “derivative” is understood by those skilled in the art. For example, a derivative can be understood as a chemical compound that is produced from another compound of similar structure in one or more steps, such as illustrated in Table 2 (infra) for benzo[c]chromen-6-one.
The present invention relates to a therapeutic formulation comprising one or more compositions useful in the treatment of fibrotic disorders. Fibrotic disorders are due to the abnormal formation of an extracellular matrix. Examples of fibrotic disorders include pulmonary fibrosis, systemic sclerosis, scleroderma, proliferative vitreoretinopathy, hepatic cirrhosis and mesangial proliferative cell disorders. Further examples of fibrotic disorders include cystic fibrosis of the pancreas and lungs, endomyocardial fibrosis, idiopathic pulmonary fibrosis of the lung, mediastinal fibrosis, myelofibrosis, retroperitoneal fibrosis, nephrogenic systemic fibrosis, progressive massive fibrosis (a complication of coal workers' pneumoconiosis) and injection fibrosis (which can occur as a complication of intramuscular injections, especially in children). Further fibrosis-associated conditions include diffuse parenchymal lung disease, post-vasectomy pain syndrome, tuberculosis (which can cause fibrosis of the lungs), sickle-cell anemia (which can cause fibrosis of the spleen) and rheumatoid arthritis.
Hepatic cirrhosis is characterized by the increase in extracellular matrix constituents resulting in the formation of a hepatic scar. Hepatic cirrhosis can cause diseases such as cirrhosis of the liver. An increased extracellular matrix resulting in a hepatic scar can also be caused by viral infection such as hepatitis.
Mesangial disorders are brought about by abnormal proliferation of mesangial cells. Mesangial hyperproliferative cell disorders include various human renal diseases, such as glomerulonephritis, diabetic nephropathy, malignant nephrosclerosis, thrombotic microangiopathy syndromes, transplant rejection, and glomerulopathies.
In accordance with the present invention, there is provided pharmaceutical compositions comprising Formula I:
where,
R1=H or alkyl;
R2=H, OH, O-alkyl, amino, O-heterocyc, O-aryl, O-substituted alkyl, where substitution is e.g. halo, aryl, or heteroaryl, O—Ac, O—PO3, O—SO3, or OSO2NH2;
R3=H, OH, O-alkyl, O—CH2Aryl, O—CH2heteroaryl, O-alkylaryl, O-acyl, or nitro;
R4=H, Alkyl, CH2Aryl, substituted alkyl, OH, O-alkyl, O-aryl, OCH2Aryl, OCH2Heteroaryl, O-Acyl, OPO3, OSO3, or OSO2NH2;
R5=H, Oxo, aryl, hydroxyl, alkyl, or O-alkyl;
R7=H, Acyl, substituted alkyl, where substitution is e.g. hydroxyl or sulfamoyl, alkyl, O-alkyl, or O-substituted alkyl where substitution is O—PO3 or OSO3;
In accordance with the present invention, there is provided pharmaceutical compositions comprising Formula II:
where,
R1=H or alkyl;
R2=H, O-alkyl, OH, amino, O-heterocyc, O-aryl, O-substituted alkyl where substitution is e.g. halo, aryl, or heteroaryl, O—Ac, O—PO3, O—SO3, or OSO2NH2;
R3=H, O-alkyl, O-substituted alkyl where substitution is aryl or heteroaryl, OH, O-acyl, or nitro;
R4=H, Alkyl, CH2Aryl, substituted alkyl, O), O-alkyl, O-aryl, OCH2Aryl, OCH2Heteroaryl, O-Acyl, OPO3, OSO3, or OSO2NH2;
R5=H, Aryl, heteroaryl or substituted alkyl; and
In accordance with the present invention, there is provided pharmaceutical compositions comprising Formula III:
where,
R1=alkyl or H;
R2=alkyl or H;
In accordance with the present invention, there is provided pharmaceutical compositions comprising Formula IV:
where,
R2=H or nitro;
R5=alkyl, substituted alkyl or aryl.
In accordance with the present invention, there is provided a pharmaceutical composition comprising a therapeutically effective amount of one or more benzo[c]chromen-6-one derivatives having the following structure depicted in Table 2:
The individual benzo[c]-chromen-6-one derivatives of Table 2 are identified by the designation “SG” followed by a number. They are alternatively referred to herein by the designation “Palomid” followed by the same number, i.e. the terms “SG” and “Palomid” are used interchangeably throughout this application.
The compounds of Table 2 exhibit anti-fibrotic activities. Those skilled in the art will appreciate that the invention includes other benzo[c]-chromen-6-one derivatives having anti-fibrotic activities.
The present invention also relates to implants or other devices comprised of one or more compositions described herein or prodrugs thereof wherein the composition or prodrug is formulated in a biodegradable or non-biodegradable format for sustained release. Non-biodegradable formats release the drug in a controlled manner through physical or mechanical processes without the format being itself degraded. Bio-degradable formats are designed to gradually be hydrolyzed or solubilized by natural processes in the body, allowing gradual release of the admixed drug or prodrug. Both bio-degradable and non-biodegradable formats and the process by which drugs are incorporated into the formats for controlled release are well known to those skilled in the art. These implants or devices can be implanted in the vicinity where delivery is desired, for example, at the site of aberrant extracellular matrix.
The present invention also relates to conjugated prodrugs and uses thereof. More particularly, the invention relates to conjugates of benzo[c]chromen-6-one derivatives and the use of such conjugates in the prophylaxis or treatment of conditions associated with uncharacteristic extracellular matrix formation.
The present invention also provides a conjugated prodrug of a benzo[c]chromen-6-one derivative conjugated to a biological activity modifying agent, e.g., a peptide, an antibody or fragment thereof, or in vivo hydrolysable esters, such as methyl esters, phosphate or sulfate groups, and amides or carbamates. Modifications can include modifying a hydroxyl group with a phosphate group. This derivative would not be expected to have activity due to the modification causing a significant change to the derivative thereby losing biological activity. However the modification imparts better solubility characteristics, i.e., more water soluble, which could facilitate transport through the blood or give it better oral availability to allow it to reach its site of activity. Once it gets into the microenvironment where it is needed to have activity, the modification is cleaved through natural processes, i.e., endogenous enzymes which are present at the site of needed activity. Alternatively it may just keep the derivative in a state to give it better systemic concentration which would then be cleaved again in the systemic circulation and thereby enhance its activity. The incorporation of benzo[c]chromen-6-one derivatives into a disease-dependently activated prodrug enables significant improvement of potency and selectivity in treating one or more disease conditions referred to hereinabove.
In addition to the compounds of the present invention, the pharmaceutical composition of this invention may also contain or be co-administered (simultaneously or sequentially) with one or more pharmacological agents of value in treating one or more disease conditions referred to hereinabove.
Furthermore, the benzo[c]chromen-6-one derivatives or prodrugs thereof may be incorporated into bio-degradable or non-degradable formats allowing for sustained release. For example, the formulation being implanted in the proximity of where the delivery is desired, at the site of a tumor or in the vicinity of aberrant vasculature. Alternatively, the pharmaceutical formulation can be packaged into a delivery vehicle that has a chemical moiety that provides for specificity. For example, the moiety can be an antibody or some other such molecule that directs and facilitates delivery of the active agent to the desirable site.
The present invention also relates to use of the benzo[c]chromen-6-one derivatives or prodrugs thereof for the preparation of a medicant for the prophylaxis or treatment of conditions associated with any disease characterized by uncharacteristic formation of fibrotic tissue, i.e. aberrant extracellular matrix formation.
The present invention also relates to the provision of a pharmaceutical composition comprising benzo[c]chromen-6-one derivatives or prodrugs thereof according to the present invention together with a pharmaceutical acceptable carrier, diluent or excipient.
The pharmaceutical composition may also be used for the prophylaxis or treatment of conditions associated with fibrotic diseases or disorders. The present invention also pertains to methods of prophylaxis or treatment of a condition associated with any fibrotic disease or disorder characterized by uncharacteristic extracellular matrix formation, said method including administering to a subject in need of such prophylaxis or treatment an effective amount of benzo[c]chromen-6-one derivatives or prodrugs thereof according to the present invention as described hereinabove. It should be understood that prophylaxis or treatment of said condition includes amelioration of said condition.
By “effective amount” it is meant a therapeutically effective amount that relieves symptoms, partially or completely, associated with a particular disease or syndrome. Such amounts can be readily determined by an appropriately skilled practitioner, taking into account the condition to be treated, the route of administration, and other relevant factors —well known to those skilled in the art. Such a person will be readily able to determine a suitable dose, mode and frequency of administration.
Pharmaceutically acceptable salts of the benzo[c]chromen-6-one derivatives or prodrugs thereof may be prepared in any conventional manner. In vivo hydrolysable esters, for example, methyl esters, phosphate or sulfate groups, and amides or carbamates may be prepared in any conventional manner.
The benzo[c]chromen-6-one derivatives or prodrugs thereof can be provided as physiologically acceptable formulations using known techniques and these formulations can be administered by standard routes. The compositions may be administered through means including, but not limited to, topical, oral, rectal or parenteral, for example, intravenous, subcutaneous or intramuscular, route. In addition, the compositions may be incorporated into formats allowing for sustained release, the formats being implanted in the proximity of where the delivery is desired, for example, at the site of the skin disease or aging skin or in the vicinity of aberrant vasculature. The dosage of the composition will depend on the condition being treated, the particular derivative used, and other clinical factors such as weight and condition of the subject and the route of administration of the compound—all of which is appreciated by those skilled in the art. For example, a person skilled in the art will be able by reference to standard texts, such as Remington's Pharmaceuticals Sciences 17th edition (the entire teaching of which is incorporated herein by reference), determine how the formulations are to be made and how these may be administered.
The formulations including, but not limited to, those suitable for oral, rectal, nasal, inhalation, topical (including, but not limited to, dermal, transdermal, buccal and sublingual), vaginal or parenteral (including, but not limited to, subcutaneous, intramuscular, intravenous, intradermal, intraocular (including, but not limited to, intra-vitreal, sub-conjunctival, sub-Tenon's, trans-scleral), intra-tracheal and epidural) and inhalation administration. The formulations may be conveniently presented in unit dosage form and may be prepared by conventional pharmaceutical techniques. Such techniques include the step of bringing into association the active ingredient and a pharmaceutical carrier(s) or excipient(s). The formulations are prepared by uniformly and intimately bringing into association the active ingredient with liquid carriers or finely divided solid carriers or both, and then, if necessary, shaping the product.
Formulations of the present invention suitable for oral administration may be presented as discrete units such as capsules, cachets or tablets each containing a predetermined amount of the active ingredient; as a powder or granules; as a solution or a suspension in an aqueous liquid or a non-aqueous liquid; or as an oil-in-water liquid emulsion or a water-in-oil emulsion, etc.
A tablet may be made by compression or molding, optimally with one or more accessory ingredient. Compressed tablets may be prepared by compressing, in a suitable machine, the active ingredient in a free-flowing form such as a powder or granules, optionally mixed with a binder, lubricant, inert diluent, preservative, surface-active or dispersing agent. Molded tablets may be made by molding, in a suitable machine, a mixture of the powdered compound moistened with an inert liquid diluent. The tablets may optionally be coated or scored and may be formulated so as to provide a slow or controlled release of the active ingredient therein.
Formulations suitable for administration via the mouth include lozenges comprising the ingredients in a flavored basis, usually sucrose and acacia or tragacanth; pastilles comprising the active ingredient in an inert basis such as gelatin and glycerin, or sucrose and acacia; and mouthwashes comprising the ingredient to be administered in a suitable liquid carrier.
Formulations suitable for topical administration to the skin may be presented as ointments, creams, gels and pastes comprising the ingredient to be administered in a pharmaceutical, cosmeceutical or cosmetic acceptable carrier. A viable delivery system is a transdermal patch containing the ingredient to be administered.
Formulations for rectal administration may be presented as a suppository with a suitable base comprising, for example, cocoa butter or a salicylate.
Formulations suitable for nasal administration, wherein the carrier is a solid, include a coarse powder having a particle size, for example, in the range of 20 to 500 microns which is administered in the manner in which snuff is taken, for example, by rapid inhalation through the nasal passage from a container of the powder held close up to the nose. Suitable formulations include wherein the carrier is a liquid for administration, as for example a nasal spray or as nasal drop, including aqueous or oily solutions of the active ingredient.
Formulations suitable for vaginal administration may be presented as pessaries, tampons, creams, gels, pastes, foams or spray formulations containing, in addition to the active ingredient, ingredients such as carriers as are known in the art to be appropriate.
Formulation suitable for inhalation may be presented as mists, dusts, powders or spray formulations containing, in addition to the active ingredient, ingredients such as carriers as are known in the art to be appropriate.
Formulations suitable for parenteral administration include aqueous and non-aqueous sterile injection solutions which may contain anti-oxidants, buffers, bacteriostatic agents and solutes which render the formulation isotonic with the blood of the intended recipient; and aqueous and non-aqueous sterile suspensions which may include suspending agents and thickening agents. The formulations may be presented in unit-dose or multi-dose containers, for example, sealed ampules and vials, and may be stored in a freeze-dried, lyophilized, conditions requiring only the addition of the sterile liquid, for example, water for injections, immediately prior to use. Extemporaneous injection solution and suspensions may be prepared from sterile powders, granules and tablets of the kinds previously described.
Acceptable unit dosage formulations are those containing a daily dose or unit, daily sub-dose, as herein above recited, or an appropriate fraction thereof, of the administered ingredient.
In addition to the ingredients mentioned above, the formulations of the present invention may include other agents conventional in the art having regard to the type of formulation in question, for example, those suitable for oral administration may include flavoring agents.
The present invention includes compositions of about 100% to about 90% pure isomers. In another aspect, the invention pertains to compositions of about 90% to about 80% pure isomer. In yet another aspect, the invention pertains to compositions of about 80% to about 70% pure isomer. In still another aspect, the invention pertains to a composition of about 70% to about 60% pure isomer. In yet a further aspect, the invention pertains to a composition of about 60% to about 50% pure isomer. However, a steriochemical isomer labeled as alpha or beta may be a mixture of both in any ratio, where it is chemically possible by one skilled in the art. Additionally, included by this invention are both classical and non-classical bio-isosteric atom and substituent replacements and are well known by one skilled in the art. Such bio-isosteric replacements include, for example, substitution of ═S or ═NH for ═O.
Known compounds that are used in accordance with the invention and precursors to novel compounds according to the invention can be purchased from commercial sources, for example, Sigma-Aldrich. Other compounds according to the invention can be synthesized according to known methods well known to those skilled in the art.
Tissue Preparation
Retinal detachments were created in adult New Zealand Red pigmented rabbits as described in Eibl et al. (Eibl K H, et al. The effect of alkylphosphocholines on intraretinal proliferation initiated by experimental retinal detachment. Invest Ophthalmol Vis Sci. 2007; 48:1305-11). Briefly, intramuscular injections of the combined drugs xylazine (3 mg/kg) and ketamine (15 mg/kg) were used for anesthesia and analgesia. Additional analgesia was provided by topical eye drops of proparacaine. A 0.25% solution of sodium hyaluronate (Healon; Pharmacia, Piscataway, N.J., in balanced salt solution (BSS; Alcon, Ft. Worth, Tex.) was infused via a glass pipette between the neural retina and RPE. The Healon is necessary to prevent spontaneous reattachment of the retina and 0.25% is the most dilute solution that maintains the detachment for extended periods. The pipette, with an external diameter of approximately 100 μm, was inserted into the eye via an incision that was made several millimeters below the pars plana to prevent the pipette from touching the lens. Approximately one-half of the inferior retina was detached in the right eye, leaving the superior attached regions as internal controls. The left eyes served as uninjected controls. Immediately after producing the detachment, 600 μg of Palomid 529 in 50 μl balance salt solution (BSS) was injected intravitreally. On day 3 after detachment, the experimental (right) eyes were given an intravitreal injection of 10 μg BrdU (Sigma, St Louis, Mich.) in 50 μl BSS. BrdU was given intravitreally on day 3 for both the 3-day and 7-day detachment experiments since it has been shown previously that the proliferative response is at its maximum at this time. Attached retinal regions within the eyes with the detachment served as control retinas labeled with BrdU. Animals were euthanized either 4 hr after the BrdU injection on day 3, or on day 7 using sodium pentobarbital (120 mg/ml, IV). Three animals were used in both 3 and 7 day experiments. Following enucleation, the eye was fixed in 4% paraformaldehyde for at least 24 hr (in 0.1M sodium cacodylate buffer, pH 7.4; Electron Microscopy Sciences, Fort Washington, Pa.). To determine potential toxic effects of the drug, six additional animals received either vehicle (BSS, n=3) or drug injections (n=3) into normal eyes. These animals were euthanized on day 15, and the eyes were fixed in 4% paraformaldehyde and the whole eyes embedded in paraffin for light microscopic evaluation. All experimental procedures conformed to the ARVO statement for the Use of Animals in Ophthalmic and Vision Research and the guidelines of the Animal Resource Center of the University of California, Santa Barbara.
Immunocytochemistry/Light Microscopy
The immunocytochemistry was performed as described in Eibl et al. with slight modifications. Pieces of retinal tissue approximately 3 mm square were excised from 3 detached regions from within each eye. The tissue was rinsed in phosphate buffered saline (PBS), embedded in low-melt agarose (5%; Sigma, St. Louis, Mich.) and sectioned at 100 μm using a vibratome (Technical Products International, Polysciences, Warrington, Pa.). Sections were incubated in normal donkey serum (1:20) in PBS, 0.5% bovine serum albumin, 0.1% triton X-100, and 0.1% azide (=PBTA) overnight at 4° C. on a rotator. The following day the sections were pre-treated with 2 N HCL for 1 hr as an antigen retrieval step for the BrdU. After rinsing in PBTA, the primary antibodies and lectin were added and incubated overnight at 4° C. on a rotator in PBTA. Anti-BrdU (1:200, Accurate Chemical and Scientific Corp., Westbury, N.Y.) was used to detect dividing cells, anti-vimentin (1:500; Dako, Carpinteria, Calif.) was used to identify Müller cells, and the isolectin B4, Griffonia Simplicifolia (1:50; Vector Labs, Burlingame, Calif.) was used to label microglia and macrophages. Following rinsing of the primary antibodies in PBTA, the secondary antibodies (streptavidin CY5, donkey anti-rat CY3, and donkey anti-mouse CY2; Jackson ImmunoResearch, West Grove, Pa.) were added together, each at 1:200 in PBTA, overnight at 4° C. on a rotator. The next day the sections were rinsed in PBTA, mounted on glass slides using 5% n-propyl gallate in glycerol with the nuclear stain Hoescht (1:5000; Invitrogen, Carlsbad, Calif.) and viewed on an Olympus Fluoview 500 laser scanning confocal microscope. Paraffin sections of whole eyes were cut at 4 μm, counter-stained with Hemotoxylin & Eosin (H&E) and photographed using a digital camera on an Olympus BX60 microscope. Since whole eyes from 3 different animals within each group were embedded and sectioned, examination of the entire length of the retina was performed in a single section and similar retinal regions from control and experimental animals were chosen to photograph.
Quantitation
At least 60 single plane confocal images at 1024×1024 pixel resolution were captured from 3 animals within each of the experimental groups (vehicle and drug treated). Similar retinal locations were examined in all animals. To quantify the effect of drug treatment on proliferation, the number of anti-BrdU labeled Müller cell nuclei was determined per millimeter of retina using the confocal images from both 3 and 7-day time-points. To quantify the effect of drug treatment on subretinal glial scar formation, scars were defined as areas of continuous cellular growth located sclerad to the OLM that were also labeled with anti-vimentin. The number of scars was counted and their length measured per mm of retina in the 7 day animals since no scars were observed at 3 days. To determine the width of the ONL, sections were stained with a fluorescent nuclear dye (Hoescht) and the ONL was automatically segmented by a statistic-based clustering method (Byun J, Ph.D. thesis, “Quantitative analysis and modeling of confocal retinal images”. Univ. Calif. Santa Barbara, June 2007). The ONL widths in the control retina were then compared to the widths in the vehicle and drug injected eyes. Only the 7-day time-point was examined since more photoreceptor cell death has occurred at this time compared to day 3. The same sections were used to quantify all of the responses described above.
Analysis of Attached Retinas
Light microscopy of paraffin embedded normal retinas and confocal microscopy of attached retinal regions labeled with various antibodies from within the detached eyes were examined to determine possible adverse affects of the drug (
Analysis of Detached Retinas
In detached retinal regions from the eyes injected with the vehicle at day 3, anti-vimentin labeling (green) extended to the outer limiting membrane (OLM), giving the Müller cells a thickened, distorted appearance within the retina (
At 3 and 7 days after detachment in the drug treated eyes, the occurrence of anti-BrdU labeled nuclei was greatly reduced (FIGS. 2C,D). Anti-vimentin labeling was somewhat elevated when compared to non-detached controls and the Müller cells appeared thickened (compare with FIGS. 1E,D) but they rarely extended into the subretinal space at either time-point; if they did, they were much smaller in size (bracket,
Quantitation
At the 3-day detachment time-point, the average number of anti-BrdU labeled Müller cell nuclei was significantly reduced from 10.79/mm of retina, in the vehicle treated control eyes, to 1.19 following drug treatment (
Specifically,
Specifically,
Specifically,
Few immune-related cells (microglia and macrophages) incorporated BrdU in either control or treated retinas, therefore, to quantify this response, the total number of isolectin B4 labeled cells were counted per millimeter of retina. At the 7-day time-point, the total number of cells decreased from an average of 43.9/mm of retina in control eyes, to 24.5/mm retina in drug treated retinas (
Specifically,
Since the outer retina appeared more organized in the drug treated eyes, as shown by the anti-vimentin labeling of Müller cells (compare FIGS. 2A,B with FIGS. 2C,D), we sought to determine if more photoreceptors were present by measuring the ONL width. Seven days of detachment resulted in a statistically significant decrease in the average thickness of the ONL from 34.45 μm in the normal retina to 19.40 μm in the vehicle treated detached retinas (p<1.27 E-11;
Specifically,
Two potentially blinding conditions that can result from retinal detachment are PVR and subretinal fibrosis, the formation of cellular membranes on the vitreal or photoreceptor surface of the retina. Currently the only treatment is surgical removal of the membranes. This, however, involves surgical intervention and is often not a permanent solution since recurrence of secondary membranes is not uncommon. Ideally a pharmacological adjunct could be given at the time of reattachment surgery to prevent membrane formation or alternatively at the time of membrane removal to prevent continued growth of the tissue. To date no pharmacological approaches have proven clinically effective at inhibiting this process. In the current invention a single injection of Palomid 529 is effective in an animal model at reducing the proliferation induced by detachment, the subsequent hypertrophy and growth of the Müller cells into the subretinal space, and the activation of microglia. In addition, there is no apparent toxicity associated with intraocular delivery of the drug and, in fact, the ONL thickness was greater in the Palomid 529 treated detached retinas, indicating some neuroprotective effect on photoreceptors. Hence this drug is useful for treating a variety of related human retinal diseases in which proliferation and/or photoreceptor cell death are components.
Typically, PVR is thought to be a condition involving undesirable cell proliferation, cell spreading and contractility. Indeed, dividing cells have been observed in membranes removed from patients with PVR. However, data from animal models suggest that in addition to proliferation, the growth and hypertrophy of Müller cells plays a role in the response perhaps by providing a cellular scaffold on which more complex membranes, involving a variety of cell types, can grow. Both proliferation and hypertrophy of Müller cells begin within the first few days after detachment. After 1 week, proliferation declines to low levels but processes from these cells continue expanding in the subretinal space, apparently as long as the retina remains detached. This is also true for the growth of epiretinal membranes in the vitreous. Müller cell growth on the vitreal surface appears to begin, however, with retinal reattachment, not detachment. Reattachment reduces the proliferative response significantly, but the growth of membranes along the vitreal retinal surface continues since large membranes are generally observed weeks to months after reattachment. The fact that PVR and subretinal fibrosis are complex combinations of proliferation and cell growth may explain why drugs that target solely proliferation such as 5-fluorouracil, were not effective at reducing epiretinal membrane formation in human patients. The Akt/mTOR pathway, through which Palomid acts, has been shown to regulate both proliferation and cell spreading. This may provide a mechanism for Palomid's dramatic reduction of both proliferation and subretinal gliosis in the rabbit model of detachment although its precise mechanism of action is not known. It is presumed that Palomid is acting directly on Müller cells since these are the most numerous cell types undergoing division. Palomid 529's effect on increased photoreceptor survival could be direct or indirect. It has been shown that activation of the PI3K/Akt signaling pathway can have a neuroprotective effect in the retina by inhibiting light-induced photoreceptor apoptosis indicating that the drug may in fact have a direct effect on photoreceptors.
Palomid 529 has an expected half-life of at least 3 months in the vitreous, enabling the observation of an effect on proliferation and scar formation 7 days after detachment. The rapid clearance of drugs such as 5-fluorouracil may contribute to its ineffectiveness in preventing PVR. While the average number of subretinal scars was reduced approximately 4 fold with the addition of Palomid 529, their length was reduced more than 20 fold. This indicates that the drug not only reduced Müller cell growth into the subretinal space, but also the actual expansion of the processes that do reach that space. This correlates with the observation that Müller cells within the retina appear less branched and tortuous in the treated eyes (see FIGS. 2C,D), indicating a result of Palomid's effect on cell spreading, in this case translated into cell hypertrophy. Clinically, Palomid 529 can prevent the formation of scars and also reduce the overall growth of scars that are already present. Finally, Palomid 529 also reduced the microglial/macrophage response, and since these cells become highly migratory when activated, this may also be a result of the anti-spreading effect of the drug.
In summary, the data presented herein indicate that Palomid 529 is an effective agent for decreasing proliferation and glial cell growth, as well as photoreceptor cell death induced by retinal detachment, and therefore represents a novel way to improve the overall outcome of repairing rhegmatogenous retinal detachments.
Methods: Experimental retinal detachments were made in the right eyes of pigmented rabbits. Six hundred micrograms of Palomid 529 in 50 microliters of PBS, or PBS alone was injected intravitreally on day 0, immediately after retinal detachment. Each rabbit received 10 micrograms of BrdU intravitreally on day 3. Animals were sacrificed on day 3 or 7, at which time the tissue was fixed in paraformaldahyde, embedded in agarose and sectioned at 100 microns. The sections were labeled with anti-BrdU, to detect dividing cells, and anti-vimentin, to identify Müller cells. Labeling was imaged on an Olympus Fluoview confocal microscope, and the resultant digital images were analyzed to determine the number of proliferating cells as well as the number and length of subretinal glial scars.
Results: In control detachments, Müller cells make up the majority of BrdU labeled cells, and are the cells that form glial scars by growing into the subretinal space. The data show a statistically significant decrease in the number of BrdU labeled Müller cells per millimeter at both the 3 (
Conclusions: The data indicate that Palomid 5299 is an effective suppressor of Müller cell proliferation and glial scar growth in a rabbit model of retinal detachment. Therefore, inhibiting the Adt/mTOR signal transduction pathway is a strategy to decrease proliferation induced by detachment and represents a novel therapy for related human diseases such as proliferative vitreoretinopathy.
Transforming growth factor-beta one (TGF-β1) and alpha-Thrombin (α-Thrombin) are known to be involved in the pathogenesis of fibrotic disease. In an in vitro model of pulmonary fibrosis, TGF-β1 stimulates myofibroblast differentiation of human lung fibroblasts characterized by expression of contractile smooth muscle (SM)-specific proteins such as SM-alpha-actin (SM-α-actin). TGF-β1 also stimulates SM-α-actin expression in human lung fibroblasts which parallels a profound induction of serum response factor (SRF) expression and activity. Increased contractile gene expression with SM-α-actin as marker, increased SRF, increased connective tissue growth factor (CTGF) and increased matrix genes (e.g. fibronectin) are examples of effects observed during myofibroblast differentiation. Myofibroblast differentiation is induced by stimulation with TGF-β1 thereby increasing markers of differentiation.
Palomid 529 inhibits TGF-β1 stimulated increases of CTGF (18% at 30 μM Palomid 529), SRF (29% at 30 μM Palomid 529) and SM-α-actin (65% at 30 μM Palomid 529) in human lung fibroblasts, see
Myofibroblast activation, as shown in
| Filing Document | Filing Date | Country | Kind | 371c Date |
|---|---|---|---|---|
| PCT/US09/38285 | 3/25/2009 | WO | 00 | 10/1/2010 |
| Number | Date | Country | |
|---|---|---|---|
| 61039146 | Mar 2008 | US |
