Bisphosphonate-EP4 agonists for selective delivery to damaged muscle

Abstract

The present invention relates to methods and uses of EP4 agonist-bisphosphonate conjugates or related compounds for selective delivery to damaged muscle.

Description

BISPHOSPHONATE-EP4 AGONISTS FOR SELECTIVE DELIVERY TO DAMAGED MUSCLEFIELD OF INVENTION

[0001] The present invention relates to conjugate compounds for use in treatment of muscle damage.BACKGROUND OF THE INVENTION

[0002] Muscle injuries are extremely common and loss of enervation due to immobilization or crushing injuries or peripheral nerve injury can lead to loss or degeneration of muscles and loss of strength and function. In addition, muscular dystrophies, for example, Duchenne Muscular Dystrophy (DMD), lead to progressive degeneration of muscles and accompanying fibrosis leading to loss of mobility and, often, to premature death. There is communication between bones and skeletal muscles and many coexisting conditions of bone loss and muscle wasting including sarcopenia [L. Bonewald. Bone 120 (2019) 212-218],

[0003] Nakamura et al., have reported on a DMD gene deletion rat model of DMD [SCIENTIFIC REPORTS | 4 : 5635 | DOI: 10.1038 / srep05635; Sugihara H, Teramoto N, Nakamura K, et al. Cellular senescence-mediated exacerbation of Duchenne muscular dystrophy. Sci Rep. 2020;10(1):16385. doi:10.1038 / s41598-020-73315-6]. These DMD- mutated rats (DMD rats) do not produce dystrophin and exhibit weight loss after 5 months of age, loss of bone density as well as a decline in muscle strength, and the emergence of degenerative / regenerative phenotypes in the skeletal muscle, heart, and diaphragm and including increased fibrosis as they mature, increased muscle fat, a decline in numbers of regenerating EMHC myofibers and loss of grip strength, which closely parallels the human DMD phenotype.

[0004] Prostaglandins are a subclass of eicosanoids found in most body tissues and implicated in a variety of physiological functions in animals, including smooth muscle contraction, reproduction, autoimmunity, inflammation, reduction of intraocular pressure, etc. Prostaglandin E2(PGE2) has been associated with muscle cell function and for augmenting regeneration and enhancing strength [Ho et al PNAS, 114(26) 6675-6684], Inhibition of COX-2 (an enzyme responsible for generating PGE2) with NSAIDs blocks muscle stem cell proliferation of human skeletal muscle [Mikkelsen UR, et al. Local NSAID infusion inhibits satellite cell proliferation in human skeletal muscle after eccentric exercise. Journal of Applied Physiology. 2009;107(5):1600-1611. doi:10.1152 / japplphysiol.00707.2009]. COX-2 deficientmice show impaired healing of muscle damage and in vitro PGE2 has been implicated in activation of myocyte regeneration [Shen et al. J Appl Physiol101: 1215-1221, 2006], Myoblasts express EP4 receptors, and PGE2 and the EP4 receptor agonist CAY10598 have been reported to promote proliferation of skeletal muscle myoblasts via EP4 receptor activation [Mo et al. Cell Cycle 14:10, 1507-1516; May 15, 2015],

[0005] PGE2 binds to four receptors (EP1 , EP2, EP3 and EP4). The EP4 receptor is associated with intracellular cyclic adenosine monophosphate (cAMP) production, and is distributed in a wide variety of tissue types suggesting a major role in PGE2-mediated biological events, such as smooth muscle relaxation, intraocular pressure, pain (in particular inflammatory, neuropathic and visceral pain), inflammation, neuroprotection, lymphocyte differentiation, bone metabolic processes, allergic activities, promotion of sleep, renal regulation, gastric or enteric mucus secretion and duodenal bicarbonate secretion.

[0006] A variety of EP4 agonists and related compounds have been described and include, without limitation, compounds as set forth in, for example, WO 02 / 24647, WO 02 / 42268, EP 1132086, EP 855389, EP 1114816, EP 2465506, WO 01 / 46140, WO 01 / 72268, WO 05 / 116010, WO 03 / 047417, W02008076703, WO 2014078446 or US 7,238,710.

[0007] PGE2 or EP4 agonists have been associated with systemic side effects, such as hypotension, headaches, and gastrointestinal disturbance which have limited their use.

[0008] Bisphosphonates are drugs used to strengthen bone and have been implicated in inhibiting bone resorption and in bone targeting.

[0009] Prostaglandin-bisphosphonate conjugate compounds have been described in for example US 5,409,911 , US 6,121 ,253, or WO 2011 / 147034.

[0010] Bisphosphonate-prostaglandin EP4 receptor agonist conjugates target and bind to bony structures throughout the body and can release the active EP4 agonist (e.g. MES-1002) in a slow and sustained manner selectively in the bone environment and have anabolic effects to repair bone defects and rebuild lost bone associated with osteoporosis and related conditions while mitigating unacceptable systemic side effects that would be elicited if the active EP4 agonist were administered directly. Such a conjugate (C3, also known as MES- 1007) has been described in US 10,400,000 and bone targeting, anabolic and repair activities have been reported [Thevenin et al., ACS Pharmacology + Translational Science, 2021, 4 (2) 908-925; Boraschi-Diaz et al., Bone. 145 (2021) 115867; Sheikh et al., J. Periodontology 2020, 25, February, 2020, 1521-1531; Sheikh et al. J Biomed Mater Res. 2020;1-11; Sheikh et al., Journal of Bone and Mineral Research Plus 2019 Nov 9;3(12):e10237; Hu et al. Osteoporosis International (2016) 27(2) 797-808; Liu et al, Journalof Bone and Mineral Research (2015) 30(4), 670-680], In experiments administering radiolabeled C3 ([3H]-MES-1007) and the radiolabeled free acid analog, [3H]-MES-1022, the radioactive drug was shown to associate with bones and organs of metabolism and elimination (liver, kidney, spleen) after in vivo administration while little detectable radioactive conjugate drug or the active EP4 agonist was detected in skeletal muscles of normal healthy animals. [Thevenin et al., ACS Pharmacology + Translational Science, 2021, 4 (2) 908-925],SUMMARY OF THE INVENTION

[0011] The present disclosure provides, in part, a method of selectively delivering anEP4 agonist or related compound to a damaged muscle, by administering a bisphosphonate- EP4 agonist conjugate or related compound to a subject in need thereof, where the bisphosphonate-EP4 agonist or related compound conjugate is selectively delivered to the damaged muscle. In some embodiments, the method includes treating or preventing damage to a muscle, or reversing or repairing a damage to a muscle.

[0012] In some aspects, the present disclosure provides a method of treating or preventing damage to a muscle, or reversing or repairing a damage to a muscle, by administering a bisphosphonate-EP4 agonist or related compound to a subject in need thereof.

[0013] In some embodiments of the present disclosure, the muscle may be a skeletal muscle, a smooth muscle or a cardiac muscle, a muscle associated with the lungs, a muscle associated with blood vessels, or a muscle associated with kidney or kidney vasculature.

[0014] In some embodiments of the present disclosure, the muscle may be damaged by injury, overuse, or due to a disease or condition that includes muscle damage.

[0015] In some embodiments of the present disclosure, the disease or condition that includes muscle damage may be a cardiac disorder (e.g., fibrotic cardiac disease or is calcification of a cardiac valve), a vascular system disorder (e.g., a vascular lesion associated with calcification), inflammatory bowel disease, a muscular dystrophy (e.g., Duchenne Muscular Dystrophy), pulmonary fibrosis, asthma, chronic obstructive pulmonary disease (COPD), or a fibrotic kidney disease.

[0016] In some embodiments of the present disclosure, the bisphosphonate-EP4 agonist may be a compound according to Formula I or a pharmaceutically acceptable salt thereof:Formula I where:X may be -CH2-, -S-, -O-, or -NH-;Y may be COOR', optionally substituted tetrazole, or C(O)NHSO2R;Z may be OH or H;R may be optionally substituted lower alkyl or optionally substituted aryl; n may be 1 , 2, or 3; m may be 0, 1 , 2, 3, 4, 5, or 6; q may be 1 , or 2;Ri may be independently H or halogen;Ar may be aryl, substituted aryl, or heteroaryl;R3may be each independently H, OR', halogen, CN, or C(O)R';R' may be each independently H or lower alkyl, or two R's may form a ring of up to 6 carbons; and may be a double or single bond.

[0017] In some embodiments of the present disclosure, the bisphosphonate-EP4 agonist may be:Sodium (4-(4-(2-(((R,E)-4-((R)-1 -(7-ethoxy-7-oxoheptyl)-5-oxopyrrolidin-2-yl)-1 ,1- difluoro-1-phenylbut-3-en-2-yl)oxy)-2-oxoethyl)benzamido)-1-hydroxybutane-1 ,1- diyl)bis(hydrogen phosphonate);Sodium (3-(4-(2-(((R,E)-4-((R)-1 -(7-ethoxy-7-oxoheptyl)-5-oxopyrrolidin-2-yl)-1 ,1- difluoro-1-phenylbut-3-en-2-yl)oxy)-2-oxoethyl)benzamido)-1-hydroxypropane-1 ,1 - diyl)bis(hydrogen phosphonate);Sodium (6-(4-(2-(((R,E)-4-((R)-1 -(7-ethoxy-7-oxoheptyl)-5-oxopyrrolidin-2-yl)-1 ,1- difluoro-1-phenylbut-3-en-2-yl)oxy)-2-oxoethyl)benzamido)-1-hydroxyhexane-1 ,1 - diyl)bis(hydrogen phosphonate);Sodium (4-(3,5-bis(2-(((R,E)-4-((R)-1 -(7-ethoxy-7-oxoheptyl)-5-oxopyrrolidin-2-yl)-1 ,1- difluoro-1-phenylbut-3-en-2-yl)oxy)-2-oxoethyl)benzamido)-1-hydroxybutane-1 ,1- diyl)bis(hydrogen phosphonate);Sodium (4-(4-(2-(((R,E)-4-((R)-1-(6-carboxyhexyl)-5-oxopyrrolidin-2-yl)-1 , 1 -difluoro-1 - phenylbut-3-en-2-yl)oxy)-2-oxoethyl)benzamido)-1-hydroxybutane-1 ,1 -diyl)bis(hydrogen phosphonate);Sodium (3-(4-(2-(((R,E)-4-((R)-1-(6-carboxyhexyl)-5-oxopyrrolidin-2-yl)-1 ,1 -difluoro-1 - phenylbut-3-en-2-yl)oxy)-2-oxoethyl)benzamido)-1 -hydroxypropane-1 ,1- diyl)bis(hydrogen phosphonate);Sodium (6-(4-(2-(((R,E)-4-((R)-1-(6-carboxyhexyl)-5-oxopyrrolidin-2-yl)-1 ,1 -difluoro-1 - phenylbut-3-en-2-yl)oxy)-2-oxoethyl)benzamido)-1 -hydroxyhexane-1 ,1 - diyl)bis(hydrogen phosphonate); orSodium (4-(3,5-bis(2-(((R,E)-4-((R)-1-(6-carboxyhexyl)-5-oxopyrrolidin-2-yl)-1 ,1-difluoro- 1 -phenylbut-3-en-2-yl)oxy)-2-oxoethyl)benzamido)-1 -hydroxybutane-1 ,1- diyl)bis(hydrogen phosphonate).

[0018] In some embodiments of the present disclosure, the bisphosphonate-EP4 agonist may be:

[0019] In some embodiments of the present disclosure, the EP4 agonist may be a compound comprising a hydroxyl group at a position equivalent to C-15 of prostaglandin E2.

[0020] In some embodiments of the present disclosure, the EP4 agonist may be: prostaglandinprostaglandinAE-1-329:pCompound A:Compound B:, wherein in Compound B, a dashed line indicates the presence or absence of a bond, A is optionally substituted phenyl, X is CH2, O or S, Y is OR1or N R1R2and R1and R2are independently H or Ci-6alkyl.

[0021] In some embodiments of the present disclosure, there is provided the use of a bisphosphonate-EP4 agonist or related compound for selective delivery of an EP4 agonist or related compound to a damaged muscle.

[0022] In some embodiments of the present disclosure, there is provided the use of a bisphosphonate-EP4 agonist or related compound for treating or preventing damage to a muscle, or reversing or repairing a damage to a muscle.

[0023] This summary does not necessarily describe all features of the invention.BRIEF DESCRIPTION OF THE DRAWINGS

[0024] These and other features will become more apparent from the following description in which reference is made to the appended drawings wherein:

[0025] Figure 1 shows distal femur trabecular bone for 7-month old DMD rats dosed weekly for 8 weeks with 3 mg / Kg MES-1022 and compared to vehicle treated DMD rats;

[0026] Figures 2A-F show the effects of MES-1022, dosed once weekly for 8 weeks, on DMD gene deletion rats compared to matched wild type rats starting at 7 months after birth evaluating A) final body weight; B) maximum tetanus force; C) Tibialis anterior muscle fibrosis by picrosirius red (PSR) staining and D) Tibialis anterior fat from % perilipin area. E)Tibialis anterior muscle weight corrected for body weight; F) number of myofibers in tibialis anterior muscle; and

[0027] Figures 3A-B show the biodistribution of radiolabel in tissues 24 hours after dosing tritium labeled MES-1022 to wild type (WT) and DMD gene deleted rats (DMD) (shown as ratio of radiolabel concentration normalized to concentration found in blood in wild type and DMD gene deleted rats). Data to measure levels of radioactivity (dpm). A) Data (as dpm / gram of tissue or mL of blood) expressed normalized relative to label found in blood which is set at 1 . B) Data (as dpm / gram of tissue or mL of blood for selected muscles normalized to amount of label found in blood.DETAILED DESCRIPTION

[0028] The present disclosure provides, in part, methods and uses of EP4 agonistbisphosphonate conjugates or related compounds in treating muscle damage.

[0029] The EP4 agonist-bisphosphonate conjugates or related compounds are selectively delivered to a site of action, such as a damaged muscle. Delivery of EP4 agonistbisphosphonate conjugates or related compounds to a damaged muscle can result in, for example, improved muscle mass and function, reduction in fibrosis, increased myofiber size, decreased fat infiltration, and / or elevated myofiber count in the damaged muscle.

[0030] Accordingly, in some aspects, the present disclosure provides a method of selectively delivering an EP4 agonist conjugate or related compound to a damaged muscle, the method including administering a bisphosphonate-EP4 agonist conjugate or related compound to a subject in need thereof, where the bisphosphonate-EP4 agonist conjugate or related compound is selectively delivered to the damaged muscle.

[0031] In alternative aspects, the present disclosure provides a method of treating or preventing damage to a muscle, or of reversing or repairing a damage to a muscle, the method including administering a bisphosphonate-EP4 agonist conjugate or related compound to a subject in need thereof. The bisphosphonate-EP4 agonist conjugate or related compound can be selectively delivered to the damaged muscle.

[0032] A “muscle” is a soft tissue. In vertebrates, a muscle can be a skeletal muscle, a smooth muscle or a cardiac muscle. A muscle may be damaged by injury or overuse, or due to a disease or condition. In some embodiments, the muscle can be a smooth muscle or a cardiac muscle. In some embodiments, the muscle can be a skeletal muscle. In some embodiments, the muscle can be a smooth muscle. In some embodiments, the muscle can be a cardiac muscle or lungs.

[0033] By “undamaged muscle” is meant normal or healthy muscle. An undamaged muscle can include without limitation a skeletal muscle, a smooth muscle or a cardiac muscle. In some embodiments, the muscle can be a smooth muscle or a cardiac muscle. In general, undamaged muscles preferentially exclude administered compounds, such as drugs, for example, when compared to blood. By “preferentially exclude” as used herein is meant the amount of an EP4 agonist or related compound, alone or conjugated with bisphosphonate as described herein (“conjugate”), present in undamaged muscle, compared to the amount of the EP4 agonist or related compound or conjugate present in blood, where the amount of the EP4 agonist or related compound or conjugate present in undamaged muscle is less than the amount of the EP4 agonist or related compound or conjugate present in blood, after administration of the conjugate. The amount of the EP4 agonist or related compound or conjugate present in undamaged muscle can be at least about 5% less than the amount of the EP4 agonist or related compound or conjugate present in blood. In alternative embodiments, the amount of the EP4 agonist or related compound or conjugate present in undamaged muscle can be at least about 5%, 6%, 7%, 8%, 9%, 10%, 11%, 12%, 13%, 14%, 15%, 16%, 17%, 18%, 19%, 20%, 21 %, 22%, 23%, 24%, 25%, 50%, 60%, 70%, 80%, 90% or 100%, less than the amount of the EP4 agonist or related compound or conjugate present in blood. In alternative embodiments, the amount of the EP4 agonist or related compound or conjugate present in undamaged muscle can be at least about 1-fold, 2-fold, 5- fold, 10-fold, 15-fold or more, less than the amount of the EP4 agonist or related compound or conjugate present in blood. The amount of the EP4 agonist or related compound or conjugate that may be present in muscle may be measured in a suitable period of time, such as 5 to 24 hours, after the initial administration.

[0034] By “damaged muscle” or “damage to a muscle” is meant any insult or injury to a muscle that results in tissue degeneration, loss of function, muscle wasting, muscle fibrosis, decreased myofiber size, decreased myofiber count, increased fat infiltration, or fibrotic infiltration. Accordingly, a damaged muscle includes without limitation injured, diseased or dystrophic muscle tissue, etc. Muscle damage can be assessed by various techniques, such as histological examination, as known in the art. In some embodiments, muscle damage can be assessed by monitoring levels of certain enzymes in the blood including, without limitation, aspartate aminotransferase (AST) and / or alanine aminotransferase (ALT).

[0035] By “reversing or repairing a damage to a muscle” is meant ameliorating damage to a muscle including without limitation, decreasing muscle degradation, decreasing fibroticlesions, decreasing fibrotic deposition, decreasing muscle fat, increasing body weight, and / or increasing muscle mass, etc.

[0036] A condition that includes muscle damage includes without limitation cardiac disorders, vascular system disorders, inflammatory bowel disease, muscular dystrophies (e.g. Duchenne Muscular Dystrophy (DMD)), pulmonary fibrosis, asthma, chronic obstructive pulmonary disease (COPD), fibrotic kidney diseases, vascular lesions associated with calcification, fibrotic cardiac diseases, calcification of cardiac valves, fibrotic kidney diseases, etc.

[0037] In some embodiments, a condition that includes muscle damage specifically excludes a condition associated with abnormal or excessive bone loss, or with abnormal or reduced bone resorption, or with abnormal calcium metabolism.

[0038] By “EP4 agonist-bisphosphonate conjugate compound” or “conjugate compound” or simply “conjugate,” as used herein, is meant a compound including an EP4 agonist or related compound linked to a bisphosphonate. Accordingly, by “conjugated” is meant the linkage of a bisphosphonate and another compound, such as an EP4 agonist or related compound, via a stable linker that may, for example, include a hydrolyzable bond such as a hydrolyzable ester, as described herein or known in the art.

[0039] In some embodiments, the stable linker may be a carbon-carbon bond, a carbonoxygen bond (an ether) or a carbon-sulfur bond (a thioether) (such as exemplified in Laurent Gil et al. Bioorganic & Medicinal Chemistry 7 (1999) 901-919 or US Patent No. 6,121 ,253) or a carbamate moiety (such as exemplified in US Patent No. 9,611 ,284). In alternative embodiments, the stable linker may include a include a hydrolyzable bond such as a hydrolyzable ester and a stable amide as described herein or known in the art. Without being bound to any particular theory, the amide linkage may be resistant to hydrolysis in vivo and may thus provide a higher chemical stability to the conjugate compound. The hydrolyzable bond, such as a hydrolyzable ester, linkage may be slowly hydrolyzed in vivo to liberate the EP4 agonist. It is to be understood that more than one EP4 agonists or related compounds may be conjugated to a linker. In some embodiments, more than one EP4 agonists or related compounds may be conjugated to a hydrolyzable linker, such as a hydrolyzable ester - linker, which may be conjugated to a single bisphosphonate.

[0040] EP4 agonist and related compounds are described in, for example, WO 02 / 24647, WO 02 / 42268, EP 1132086, EP 855389, EP 1114816, EP 2465506, WO 01 / 46140, WO 01 / 72268, WO 05 / 116010, WO 03 / 047417, W02008076703, WO 2014078446, US 7, 238,710 etc. and include, without limitation, compounds containing at least one hydroxylgroup, as described herein or known in the art, that may in some embodiments be capable of forming a linkage, such as an ester linkage, with another compound. In some embodiments, EP4 agonists having a hydroxyl group at position “C-15” (nomenclature based on the corresponding numbering of prostaglandin E2), may be used to prepare conjugate compounds as described herein. In some embodiments, EP4 agonists include compounds described herein or known in the art that have a hydroxyl group at a position equivalent to C- 15 of prostaglandin E2and that may be used to prepare conjugate compounds as described herein. In some embodiments, EP4 agonists include compounds described herein or known in the art that have carbon in place of nitrogen in the central ring of a structure according to Formula I.

[0041] An “EP4 agonist” moiety, as described herein, is the portion of an EP4 agonist or related compound (a “related moiety”) that is conjugated via a hydroxyl group, such as the C- 15 or equivalent hydroxyl group through, for example, an ester or other hydrolyzable moiety, to another compound, such as a linker, for example, an amide containing linker, to a bisphosphonate moiety, in the context of a conjugate compound.

[0042] In some embodiments, an EP4 agonist may have the following general structure:

[0043] where X may be -CH2-, -S-, -O-, or -NH-; Y may be COOR', optionally substituted tetrazole, or C(O)NHSO2R; R may be optionally substituted lower alkyl or optionally substituted aryl; n may be 1 , 2, or 3; Ri may be independently H or halogen; Ar may be aryl, substituted aryl, or heteroaryl; R' may be H or lower alkyl; and may be a double or single bond. It is to be noted that the position equivalent to C-15 of prostaglandin E2is indicated.

[0044] In some embodiments, an EP4 agonist having a hydroxyl group at a position equivalent to C-15 of prostaglandin E2may be optionally substituted in the alkyl chain. In some embodiments, the alkyl chain of such an EP4 agonist compound may be saturated or unsaturated. In some embodiments, an EP4 agonist having a hydroxyl group at a positionequivalent to C-15 of prostaglandin E2compound may have a heteroatom (such as sulfur) in the alkyl chain, as found for example in an ONO agonist.

[0045] In some embodiments, an EP4 agonist compound may include, without limitation:p , e inCompound B, a dashed line indicates the presence or absence of abond, A is optionally substituted phenyl, X is CH2, O or S, Y is OR1or N R1R2and R1and R2are independently H or Ci.6alkyl, CP-536,745-01 , CP-043,305-02, CP- 044,519-02 or ONO-4232.

[0046] By “bisphosphonate” as used herein is meant a compound including two phosphate groups joined by a central carbon atom. In some embodiments, a bisphosphonate as used herein may include carbon, oxygen, sulfur or nitrogen atoms. In some embodiments, a bisphosphonate as used herein is an amino-bisphosphonate compound. In some embodiments, a bisphosphonate as used herein is an alkyl bisphosphonate or a thiobisphosphonate. A bisphosphonate can be coupled for example via a hydrolysable moiety such as a hydrolyzable ester to a linker through a carbon-carbon bond or a carbon-oxygen bond or a carbon-sulfur bond or through a carbamate bond. Any known bisphosphonate which is capable of coupling to an EP4 agonist or related compound or other compound, such as via a linker, and which targets in vivo to bone may be used, whether or not that particular bisphosphonate has bone resorption inhibiting activity. In some embodiments, a suitable bisphosphonate may exhibit poor or no bone resorption inhibiting activity.

[0047] In some embodiments, amino-bisphosphonates may have the following general structure, where m may be 1 , 2, 3, 4, 5 or 6.

[0048] Amino-bisphosphonates include, without limitation, alendronic acid, 4-amino-1- hydroxybutylidene-1 , 1-bisphosphonic acid; alendronate (also known as alendronate sodium or alendronate monosodium trihydrate), 4-amino-1-hydroxybutylidene-1 , 1-bisphosphonic acid monosodium trihydrate; alendronic acid and alendronate are described in U. S. Patents 4,922,007, to Kieczykowski et al., issued May 1 ,1990; 5,019,651 , to Kieczykowski et al., issued May 28,1991 ; 5,510,517, to Dauer ef al., issued April 23,1996; 5,648,491 , to Dauer ef al., issued July 15,1997; 6-amino-1-hydroxyhexylidene-1 , 1 -bisphosphonic acid (neridronate); 3-amino-1-hydroxypropylidene-1 , 1-bisphosphonic acid (pamidronate); or pharmaceutically acceptable salts thereof, or mixtures thereof.

[0049] A “bisphosphonate moiety,” as used herein, is the portion of a bisphosphonate that is conjugated to another compound, such as a linker, in the context of a conjugate compound, as described herein.

[0050] Examples of EP4 agonists include A and B and examples of clinically active bisphosphonates (BPs) include alendronate / alendronic acid (C), pamidronate (D) or neridronate (E).

[0051] An example of a thioether containing linker conjugate is shown in (G) and carbamate containing linker is shown in (F)

[0052] By an amide, or other, linker, as used herein, is meant a moiety, as described herein or known in the art, which may be used to link a hydroxyl group, such as the C-15 or equivalent hydroxyl group, of an EP4 agonist or related compound via a hydrolyzable moiety such as a hydrolyzable ester moiety which is then further attached with the amino or other group of a bisphosphonate. In some embodiments, a suitable amide or other linker may be capable of being conjugated, via an ester or other hydrolyzable unit, with a hydroxyl group, such as the C-15 or equivalent hydroxyl group, of an EP4 agonist or related compound. In some embodiments, a suitable amide or other linker may be capable of being conjugatedwith the amino or other group of a bisphosphonate to form an amide or other bond. In some embodiments, a suitable amide or other linker may be capable of being conjugated, via an ester or other hydrolyzable unit, with a hydroxyl group, such as the C-15 or equivalent hydroxyl group, of an EP4 agonist or related compound, and also with the amino or other group of a bisphosphonate to form a corresponding bond ( / .e., a bifunctional linker). In some embodiments, a suitable amide or other linker may be capable of being conjugated, via an ester or other hydrolyzable unit, with the hydroxyl groups, such as the C-15 or equivalent hydroxyl groups, of multiple EP4 agonists or related compounds, and also with the amino or other group of a single bisphosphonate.

[0053] In some embodiments, a suitable amide or other linker may contain a carboxylic acid group capable of reacting with a hydroxyl group, such as the C-15 or equivalent hydroxyl group, of an EP4 agonist or related compound to form an ester or other hydrolyzable linkage. In some embodiments, a suitable amide or other linker may contain a carboxylic acid group capable of reacting with the amino or other group of a bisphosphonate. In some embodiments, a suitable amide or other linker may contain carboxylic acid groups capable of reacting with a hydroxyl group, such as the C-15 or equivalent hydroxyl group, of an EP4 agonist or related compound, to form an ester or other hydrolyzable linkage, and with the amino or other group of a bisphosphonate to form an amide or other bond. In some embodiments, a suitable amide or other linker may be a bifunctional dicarboxylic acid chain up to about 12 carbons in length, optionally including an aryl and / or heteroatoms (for example, O, S, or N), where one of the carboxylic acid groups may be capable of reacting with a hydroxyl group, such as the C-15 or equivalent hydroxyl group, of an EP4 agonist or related compound, to form an ester or other hydrolyzable linkage, and the other carboxylic acid group may be capable of reacting with the amino or other group of a bisphosphonate to form an amide or other bond. In some embodiments, a suitable amide or other linker may include one or more aliphatic carboxylic acid groups capable of reacting with a hydroxyl group, such as the C-15 or equivalent hydroxyl group, of an EP4 agonist or related compound, to form an ester or other hydrolyzable linkage. In some embodiments, a suitable amide or other linker may include an aromatic carboxylic acid group (a benzoic acid moiety) that is capable of reacting with the amino or other group of a bisphosphonate (NHR”) to form an amide or other bond.

[0054] In some embodiments, a suitable amide forming linker may have the following general structure wherein the aromatic carboxylic acid can be condensed with an amino containing bisphosphonate to form an amide bond:where R3may each independently be H, OR', halogen, CN, or C(O)R'; and R' may each independently be H or lower alkyl, or two R's may form a ring of up to 6 carbons; where one of the carboxylic acid groups may be capable of reacting with a hydroxyl group, such as the C-15 or equivalent hydroxyl group, of an EP4 agonist or related compound, to form an ester linkage, and the other carboxylic acid group (e.g., the benzoic acid moiety) may be capable of reacting with the amino group of a bisphosphonate to form an amide bond.

[0055] In some embodiments, a suitable amide linker may have the following general structure:where R3may each independently be H, OR', halogen, CN, or C(O)R'; and R' may each independently be H or lower alkyl, or two R's may form a ring of up to 6 carbons; where the carboxylic acid group may be capable of reacting with a hydroxyl group, such as the C-15 or equivalent hydroxyl group, of an EP4 agonist or related compound, to form an ester linkage, and the other carboxylic acid group (e.g., the benzoic acid moiety) may be capable of reacting with the amino group of a bisphosphonate (NHR”) to form an amide bond.

[0056] In some embodiments, a suitable amide linker may have the following general structure:where q may be 1 or 2, R3may each independently be H, OR', halogen, CN, or C(O)R'; and R' may each independently be H or lower alkyl, or two R's may form a ring of up to 6 carbons; where one or more of the carboxylic acid groups may be capable of reacting with a hydroxyl group, such as the C-15 or equivalent hydroxyl group, of an EP4 agonist or related compound, to form an ester linkage, and the remaining carboxylic acid group (e.g., the benzoic acid moiety) may be capable of reacting with the amino group of a bisphosphonate (NHR”) to form an amide bond. In some embodiments, the carboxylic acid groups depicted as “q” may be aliphatic carboxylic acids.

[0057] In some embodiments, a suitable amide linker may have the following general structure:

[0058] where n may be 1 , 2 or 3; q may be 1 or 2; R3may each independently be H, OR', halogen, CN, or C(O)R'; and R' may each independently be H or lower alkyl, or two R's may form a ring of up to 6 carbons; where one or more of the carboxylic acid groups may be capable of reacting with a hydroxyl group, such as the C-15 or equivalent hydroxyl group, of an EP4 agonist or related compound, to form an ester linkage, and the remaining carboxylic acid group (e.g., the benzoic acid moiety) may be capable of reacting with the amino group of a bisphosphonate (NHR”) to form an amide bond. In some embodiments, the carboxylic acid groups depicted as “q” may be aliphatic carboxylic acids.

[0059] In some embodiments, a suitable amide linker may include, without limitation, 4- (carboxymethyl) benzoic acid or 3,5-bis-(carboxymethyl)benzoic acid.

[0060] In some embodiments, bisphosphonate-EP4 agonist compounds according to the present disclosure include a compound according to Formula I, or a pharmaceutically acceptable salt thereof:Formula I where:X may be -CH2-, -S-, -O-, or -NH-;Y may be COOR', optionally substituted tetrazole, or C(O)NHSO2R;Z may be OH or H;R may be optionally substituted lower alkyl or optionally substituted aryl; n may be 1 , 2, or 3; m may be 0, 1 , 2, 3, 4, 5, or 6; q may be 1 , or 2;Ri may be independently H or halogen;Ar may be aryl, substituted aryl, or heteroaryl;R3may be each independently H, OR', halogen, CN, or C(O)R';R' may be each independently H or lower alkyl, or two R's may form a ring of up to 6 carbons; and may be a double or single bond.

[0061] It is to be noted that the position equivalent to C-15 of prostaglandin E2is indicated in Formula I.

[0062] “Alkyl” as used herein refers to a straight or branched hydrocarbon chain group consisting solely of carbon and hydrogen atoms, containing no unsaturation and including, for example, from one to ten carbon atoms (“lower alkyl”), and which is attached to the rest of the molecule by a single bond. Unless stated otherwise specifically in the specification, the alkyl group may be optionally substituted by one or more substituents as described herein. Unless stated otherwise specifically herein, it is understood that the substitution can occur on any carbon of the alkyl group. Examples of straight or branched chain alkyl groups include, but are not limited to, methyl, trifluoromethyl, ethyl, 1 -propyl, 2-propyl, 1 -butyl, 2-butyl, 2- methyl-1 -propyl, 2-methyl-2-propyl, 1 -pentyl, 2-pentyl, 3-pentyl, 2-methyl-1 -butyl, 3-methyl-1- butyl, 2-methyl-3-butyl, 2, 2-dimethyl-1 -propyl, 1 -hexyl, 2-hexyl, 3-hexyl, 2-methyl-1 -pentyl, 3- methyl-1 -pentyl, 4-methyl-1 -pentyl, 2-methyl-2-pentyl, 3-methyl-2-pentyl, 4-methyl-2-pentyl, 2,2-dimethyl-1-butyl, 3,3-dimethyl-1-butyl, 2-ethyl-1 -butyl, 1-heptyl, or 1-octyl.

[0063] By a “ring structure” is meant a cycloalkyl, aryl, heteroaryl, or any cyclic structure that may be optionally substituted.

[0064] “Aryl” as used herein refers to a monocylic or bicycled ring structure wherein all rings are aromatic and are formed of carbon atoms, for example, phenyl or naphthyl groups. Unless stated otherwise specifically herein, the term “aryl” is meant to include aryl groups optionally substituted by one or more substituents as described herein. Accordingly, in some embodiments, the term “aryl” may refer to heteroaryl with, for example, rings of 5 or 6 or more atoms containing one or two heteroatoms such as N, S, or O.

[0065] “Halo” refers to halogen groups such as bromo, chloro, fluoro, iodo, etc. In some embodiments, suitable halogens include fluorine.

[0066] Any group described herein, such as alkyl, aryl, tetrazole, etc., may be substituted or unsubstituted. When substituted, a group may be substituted with any desired substituent or substituents such as one or more of the following group: H, alkyl (C1-10), alkenyl (C2-w), alkynyl (C2.i0), aryl (5-12 members), arylalkyl, arylalkenyl, or arylalkynyl, each of which may optionally contain one or more heteroatoms selected from O, S, P, N, F, Cl, Br, I, or B, and each of which may be further substituted, for example, by =O; or optionally substituted formsof acyl, arylacyl, alkyl- alkenyl-, alkynyl- or arylsulfonyl and forms thereof which contain heteroatoms in the alkyl, alkenyl, alkynyl or aryl moieties; halogen (e.g., chloro, iodo, bromo, or fluoro); hydroxyl; Ci-i0alkoxyl; amino (primary, secondary, or tertiary); nitro; thiol; thioether; imine; cyano; amido; carbamoyl; phosphonato; bisphosphonate; phosphine; carboxyl; thiocarbonyl; sulfonyl; sulfonamide; ketone; aldehyde; ester; oxo; haloalkyl (e.g., trifluoromethyl); cycloalkyl, which may be monocyclic or fused or non-fused polycyclic (e.g., cyclopropyl, cyclobutyl, cyclopentyl, or cyclohexyl), or non-aromatic heterocyclic, which may be monocyclic or fused or non-fused polycyclic (e.g., pyrrolidinyl, piperidinyl, piperazinyl, morpholinyl, or thiazinyl); and aromatic carbocyclic or heterocyclic, monocyclic or fused or non-fused polycyclic (e.g., phenyl, naphthyl, pyrrolyl, indolyl, furanyl, thiophenyl, imidazolyl, oxazolyl, isoxazolyl, thiazolyl, triazolyl, tetrazolyl, pyrazolyl, pyridinyl, quinolinyl, isoquinolinyl, acridinyl, pyrazinyl, pyridazinyl, pyrimidinyl, benzimidazolyl, benzothiophenyl, or benzofuranyl). Specific substituent groups include benzyloxy; O-alkyl; O-aryl; aryl; aryl-lower alkyl, etc. A substituted group may have 1 , 2, 3, 4, 5, 6, 7, 8, 9 or 10 substituent groups. In some embodiments, these substituent groups may optionally be further substituted with a substituent as listed herein. Substituents may also be optionally substituted by a bridge structure, for example -OC(O)O- or -OC(O)NH-. In some embodiments, substituents are not further substituted.

[0067] “Optional” or “optionally” means that the subsequently described event of circumstances may or may not occur, and that the description includes instances where said event or circumstance occurs and instances in which it does not. For example, “optionally substituted alkyl” means that the alkyl group may or may not be substituted and that the description includes both substituted alkyl groups and alkyl groups having no substitution. Examples of optionally substituted alkyl groups include, without limitation, methyl, ethyl, propyl, etc. Similarly, “optionally substituted tetrazole” means that the tetrazole group may or may not be substituted and the description includes both substituted tetrazoles and tetrazoles having no substitution.

[0068] Compounds may be in acid, base, or salt form.

[0069] Throughout this application, it is contemplated that the term “compound” or “compounds” refers to the compounds and conjugates discussed herein and includes precursors, intermediates, and derivatives of the compounds, including acyl-protected derivatives, and pharmaceutically acceptable salts of the compounds, precursors, and derivatives. The invention also includes prodrugs of the compounds, pharmaceutical compositions including the compounds and a pharmaceutically acceptable carrier, andpharmaceutical compositions including prodrugs of the compounds and a pharmaceutically acceptable carrier.

[0070] In some embodiments, all of the compounds of the invention contain at least one chiral center. In some embodiments, the compounds of the invention can have one or more chiral centers and / or double bonds. In some embodiments, the formulations, preparation, and compositions including compounds according to the invention can include mixtures of stereoisomers, individual stereoisomers, and enantiomeric mixtures, mixtures of multiple stereoisomers, double-bond isomers ( / .e., geometric EIZ isomers) or diastereomers (e.g., enantiomers (i.e., (+) or (-)) or cis / trans isomers). In some embodiments, the chemical structures depicted herein, and therefore the compounds of the invention, encompass all of the corresponding stereoisomers, that is, both the stereomerically pure form (e.g., geometrically pure, enantiomerically pure, or diastereomerically pure) and enantiomeric and stereoisomeric mixtures, e.g., racemates. In general, the compound may be supplied in any desired degree of chiral purity.

[0071] Enantiomeric and stereoisomeric mixtures of compounds of the invention can typically be resolved into their component enantiomers or stereoisomers by well-known methods, such as chiral-phase gas chromatography, chiral-phase high performance liquid chromatography, crystallizing the compound as a chiral salt complex, or crystallizing the compound in a chiral solvent. Enantiomers and stereoisomers can also be obtained from stereoisomerically or enantiomerically pure intermediates, reagents, and catalysts by well- known asymmetric synthetic methods.

[0072] In some embodiments, an EP4 agonist-bisphosphonate conjugate compound can be:

[0073] Sodium (4-(4-(2-(((R,E)-4-((R)-1-(7-ethoxy-7-oxoheptyl)-5-oxopyrrolidin-2-yl)-1 ,1- difluoro-1 -phenylbut-3-en-2-yl)oxy)-2-oxoethyl)benzamido)-1 -hydroxybutane-1 ,1 - diyl)bis(hydrogen phosphonate);

[0074] Sodium (3-(4-(2-(((R,E)-4-((R)-1-(7-ethoxy-7-oxoheptyl)-5-oxopyrrolidin-2-yl)-1 ,1- difluoro-1-phenylbut-3-en-2-yl)oxy)-2-oxoethyl)benzamido)-1-hydroxypropane-1 ,1- diyl)bis(hydrogen phosphonate);

[0075] Sodium (6-(4-(2-(((R,E)-4-((R)-1-(7-ethoxy-7-oxoheptyl)-5-oxopyrrolidin-2-yl)-1 ,1- difluoro-1-phenylbut-3-en-2-yl)oxy)-2-oxoethyl)benzamido)-1-hydroxyhexane-1 ,1- diyl)bis(hydrogen phosphonate);

[0076] Sodium (4-(3,5-bis(2-(((R,E)-4-((R)-1-(7-ethoxy-7-oxoheptyl)-5-oxopyrrolidin-2-yl)-1 ,1- difluoro-1 -phenylbut-3-en-2-yl)oxy)-2-oxoethyl)benzamido)-1 -hydroxybutane-1 ,1 - diyl)bis(hydrogen phosphonate);

[0077] Sodium (4-(4-(2-(((R,E)-4-((R)-1-(6-carboxyhexyl)-5-oxopyrrolidin-2-yl)-1 ,1-difluoro-1- phenylbut-3-en-2-yl)oxy)-2-oxoethyl)benzamido)-1-hydroxybutane-1 ,1-diyl)bis(hydrogen phosphonate);

[0078] Sodium (3-(4-(2-(((R,E)-4-((R)-1-(6-carboxyhexyl)-5-oxopyrrolidin-2-yl)-1 ,1-difluoro-1- phenylbut-3-en-2-yl)oxy)-2-oxoethyl)benzamido)-1 -hydroxypropane-1 ,1 -diyl)bis(hydrogen phosphonate);

[0079] Sodium (6-(4-(2-(((R,E)-4-((R)-1-(6-carboxyhexyl)-5-oxopyrrolidin-2-yl)-1 ,1-difluoro-1- phenylbut-3-en-2-yl)oxy)-2-oxoethyl)benzamido)-1-hydroxyhexane-1 ,1-diyl)bis(hydrogen phosphonate); or

[0080] Sodium (4-(3,5-bis(2-(((R,E)-4-((R)-1-(6-carboxyhexyl)-5-oxopyrrolidin-2-yl)-1 ,1- difluoro-1 -phenylbut-3-en-2-yl)oxy)-2-oxoethyl)benzamido)-1 -hydroxybutane-1 ,1 - diyl)bis(hydrogen phosphonate).

[0081] In some embodiments, an EP4 agonist-bisphosphonate conjugate compound can be:C3 (MES-1007) MES-1022

[0082] In some embodiments, an EP4 agonist-bisphosphonate conjugate compound or related compound, as described herein, may be selectively delivered to damaged muscle. The selective delivery can be to muscles in close proximity to bones and also to muscles more remote from bones. In some embodiments, the selective delivery can be to damaged muscles more remote from bones, such as cardiac muscle, muscles associated with the lungs or muscles associated with blood vessels or muscles associated with kidney or kidney vasculature.

[0083] By “selectively delivered” or “selective delivery” as used herein is meant the amount of EP4 agonist or related compound and / or conjugate compound present in damaged muscle, compared to the amount of EP4 agonist or related compound and / or conjugate compound present in undamaged muscle, where the amount of EP4 agonist or related compound and / or conjugate compound present in damaged muscle is greater than the amount of EP4 agonist or related compound and / or conjugate compound present in undamaged muscle, after administration of the conjugate compound. Alternatively oradditionally, by “selectively delivered” or “selective delivery” is meant the amount of EP4 agonist or related compound and / or conjugate compound present in damaged muscle, compared to the amount of EP4 agonist or related compound and / or conjugate compound present in blood, where the amount of EP4 agonist or related compound and / or conjugate compound present in damaged muscle is greater than the amount of EP4 agonist or related compound and / or conjugate compound present in blood, after administration of the conjugate compound. The amount of EP4 agonist or related compound and / or conjugate compound present in damaged muscle can be at least about 5% greater than the amount of EP4 agonist or related compound and / or conjugate compound present in undamaged muscle or blood. In alternative embodiments, the amount of EP4 agonist or related compound and / or conjugate compound present in damaged muscle can be at least about 5%, 6%, 7%, 8%, 9% 10%, 11%, 12%, 13%, 14%, 15%, 16%, 17%, 18%, 19%, 20%, 21%, 22%, 23%, 24%, 25%, 50%, 60%, 70%, 80%, 90% or 100%, greater than the amount of EP4 agonist or related compound and / or conjugate compound present in undamaged muscle or blood. In alternative embodiments, the amount of EP4 agonist or related compound and / or conjugate compound present in damaged muscle can be at least about 1-fold, 2-fold, 5-fold, 10-fold, 15-fold or more, greater than the amount of EP4 agonist or related compound and / or conjugate compound present in undamaged muscle or blood. The amount of the EP4 agonist or related compound and / or conjugate compound that may be present in muscle may be measured in a suitable period of time, such as 1 to 48 hours, or 5 to 24 hours, or more than 48 hours, after the initial dosage. In some embodiments, the measurement can be performed prior to the initiation of hydrolysis of the conjugate compound.

[0084] In some embodiments, an EP4 agonist-bisphosphonate conjugate compound or related compound, as described herein, may exhibit efficient uptake to muscle. By “efficient uptake” as used herein is meant the amount of conjugate compound in muscle as a percentage of the initial dosage. In alternative embodiments, by “efficient uptake” as used herein is meant the uptake of at least about 1%, or at least about 5%, of an EP4 agonistbisphosphonate conjugate compound as described herein, compared to the initial dosage. In alternative embodiments, at least about 1 %, 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9% 10%, 11%, 12%, 13%, 14%, 15%, 16%, 17%, 18%, 19% 20%, 21%, 22%, 23%, 24%, 25%, or more, of an EP4 agonist-bisphosphonate conjugate compound or related compound as described herein, may be present in muscle in a suitable period of time, such as 5 to 24 hours, after the initial dosage but prior to the initiation of hydrolysis of the conjugate compound.

[0085] The conjugate compounds may be hydrolyzable in vivo to release the EP4 agonist or or related compound, conjugated to the bisphosphonate. In some embodiments, the EP4 agonist or related bisphosphonate conjugate compounds may be hydrolyzable in vivo to release one or more EP4 agonists or related compounds only (with a free alcohol, such as the C-15 or equivalent position), and not the bisphosphonate, which may remain conjugated to the linker. Without being bound to any particular theory, the linkage may result in increased stability of the conjugate compounds. For example, conjugates 1_(alendronate conjugate), 2_(pamidronate conjugate), or 3_(neridronate conjugate), which contain an EP4 agonist linked through the C-15 hydroxyl via an ester linker to the bisphosphonate moiety, may be hydrolyzed in vivo to release the EP4 agonist and result in the formation of fragments 4, 5, or 6, which contain the linker attached to the bisphosphonate moiety via an amide group.

[0086] In alternative embodiments, the conjugate compounds may be inactive until hydrolyzed and the agents conjugated to the bisphosphonates are released. For example, EP4 agonist or related -bisphosphonate conjugate compounds may be inactive untilhydrolyzed, releasing only the EP4 agonist or related compound moieties. In some embodiments, the linkage of the EP4 agonists or related compounds through the C-15 hydroxyl via an ester bond may allow slow release of the EP4 agonists or related compounds. The EP4 agonist moieties or related compounds, containing a free alcohol at for example C-15, may be active. In some embodiments, the conjugate compounds may be inactive until they are hydrolyzed and the agents conjugated to the bisphosphonate moiety and amide linker released. For example, EP4 agonist or related -bisphosphonate conjugate compounds may be inactive until they are hydrolyzed and the EP4 agonist moieties or related compounds conjugated to the bisphosphonate moiety and amide linker released.

[0087] By “release” as used herein is meant the liberation of the agent(s) conjugated to the bisphosphonate such as by hydrolysis or enzyme action, from a conjugate compound. In alternative embodiments, by “release” as used herein is meant the liberation of one or more EP4 agonist moieties or related compounds, for example, by hydrolysis or enzyme action, from an EP4 agonist or related -bisphosphonate conjugate compound as described herein. In alternative embodiments, at least about 1% to about 100%, or at least about 5% to about 100%, for example, about 1%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9% 10%, 11%, 12%, 13%, 14%, 15%, 20%, 25%, 30%, 35%, 40%, 45%, 50%, 55%, 60%, 65%, 70%, 75%, 80%, 85%, 90%, 95%, or 100% or any value there between, of the EP4 agonists or related compounds may be released from an EP4 agonist or related -bisphosphonate conjugate compound, as described herein, in a suitable period of time. The release may be measured, for example, in muscle, blood and / or plasma, or in any suitable system or assay described herein or known in the art. The release may also be measured by loss of radiolabel associated with the EP4 agonist or related compound after various time periods when compared to earlier time periods. In alternative embodiments, the release may take a period of time, for example, about 1 day to about 30 days, or any value or set of values between this range, for example, about 7 days to about 14 days, such as about 7, 8, 9, 10, 11 , 12, 13, or 14 days.

[0088] EP4 agonist-bisphosphonate conjugates or related compounds may be prepared as described herein or elsewhere. It is to be understood that modifications of the methods and schemes as described herein, when performed using standard techniques or achieved by routine experimentation, are encompassed herein.

[0089] In some embodiments, suitable conjugates may be prepared, for example, by linking the hydroxyl moiety of a compound (e.g., EP4 agonists or related compounds) using bisphosphonate for example one with a free primary or secondary amino moiety, via a linker,such as an amide linker, using the techniques described herein or modifications thereof, as known in the art.Therapeutic Indications

[0090] A variety of conditions or disorders in humans and other mammals involve or are associated with muscle damage, as described herein or known in the art.

[0091] Accordingly, the conjugate compounds, as described herein, may be used to treat, prevent or repair conditions or disorders associated with muscle damage. In some embodiments, conjugate compounds including multiple EP4 agonist moieties or related compounds may be particularly useful.

[0092] In alternative embodiments, the present disclosure provides methods of treating, preventing or repairing conditions or disorders associated with muscle damage in animal subjects, such as, veterinary and human subjects.

[0093] The effectiveness of the conjugates in treating, preventing or repairing conditions or disorders associated with muscle damage may be confirmed by testing the ability of the conjugates to improve muscle mass and function, reduce fibrosis, increase myofiber size, decrease fat infiltration, and / or elevate myofiber count in damaged muscle, or by measuring targeting of the conjugates to, or retention in, damaged muscle compared to blood or undamaged muscle, using standard techniques.

[0094] In general, the methods of the invention are effected by administering a conjugate compound according to the present disclosure to a subject in need thereof, or by contacting a cell or a sample with a compound according to the present disclosure, for example, a pharmaceutical composition comprising a therapeutically effective amount of the conjugate compound.Pharmaceutical & Veterinary Compositions, Dosages, And Administration

[0095] Pharmaceutical compositions including the conjugate compounds according to the present disclosure, or for use according to the present disclosure, are contemplated as being within the scope of the present disclosure. In some embodiments, pharmaceutical compositions including an effective amount of a conjugate compound as described herein are provided. In some embodiments, the conjugate compounds according to the present disclosure selectively target damaged muscle. Such a site includes both the area in the immediate vicinity to a section of bone or group of bones or remote from bones (such as cardiac muscle). The conjugate compounds and their pharmaceutically acceptable salts,stereoisomers, solvates, and derivatives may be useful for delivery to damaged muscle because they have pharmacological activity in animals, including humans. In some embodiments, the conjugate compounds according to the present disclosure may be stable in plasma, when administered to a subject. In alternative embodiments, the EP4 agonist or other agent -bisphosphonate conjugate compounds may be administered at lower doses compared to each of the individual components. In some embodiments, the EP4 agonist or other agent -bisphosphonate conjugate compounds may reduce the systemic side effects associated with EP4 agonists.

[0096] In some embodiments, conjugate compounds according to the present disclosure, or for use according to the present disclosure, may be provided in combination with any other active agents or pharmaceutical compositions where such combined therapy is useful to treat or prevent conditions or disorders associated with muscle damage. In some embodiments, conjugate compounds according to the invention, or for use according to the present disclosure, may be provided in combination with one or more agents useful in the prevention or treatment of conditions or disorders associated with muscle damage. Combinations of conjugate compounds according to the present disclosure, or for use according to the present disclosure, and other therapies useful in the prevention or treatment of conditions or disorders associated with muscle damage, may be administered separately or in conjunction. The administration of one agent or conjugate compound may be prior to, concurrent to, or subsequent to the administration of other agent(s) or conjugate compounds.

[0097] In alternative embodiments, while the conjugate compounds according to the invention may themselves be considered “prodrugs,” the conjugate compounds may be supplied as further prodrug or protected forms, which release the compound after administration to a subject. For example, the compound may carry a protective group which is split off by hydrolysis in body fluids, e.g., in the bloodstream, thus releasing the active compound or is oxidized or reduced in body fluids to release the compound. Accordingly, a “prodrug” is meant to indicate a compound that may be converted under physiological conditions (e.g., enzymatically) or by solvolysis to a biologically active compound of the invention. Thus, the term “prodrug” refers to a metabolic precursor of a compound of the invention that is pharmaceutically acceptable. A prodrug may be inactive when administered to a subject in need thereof, but is converted in vivo to an active compound of the invention. Prodrugs are typically rapidly transformed in vivo to yield the parent compound of the invention, for example, by hydrolysis. The prodrug compound often offers advantages of solubility, tissue compatibility or delayed release in a subject. The term “prodrug” is alsomeant to include any covalently bonded carriers which release the active compound of the invention in vivo when such prodrug is administered to a subject. Prodrugs of a compound of the invention may be prepared by modifying functional groups present in the compound of the invention in such a way that the modifications are cleaved, either in routine manipulation or in vivo, to the parent compound of the invention. Prodrugs include compounds of the invention wherein a hydroxy, amino or mercapto group is bonded to any group that, when the prodrug of the compound of the invention is administered to a mammalian subject, cleaves to form a free hydroxy, free amino or free mercapto group, respectively. Examples of prodrugs include, but are not limited to, acetate, formate and benzoate derivatives of alcohol and acetamide, formamide, and benzamide derivatives of amine functional groups in the compounds of the invention and the like. A discussion of prodrugs may be found in “Smith and Williams’ Introduction to the Principles of Drug Design,” H.J. Smith, Wright, Second Edition, London (1988); Bundgard, H., Design of Prodrugs (1985), pp. 7-9, 21-24 (Elsevier, Amsterdam); The Practice of Medicinal Chemistry, Camille G. Wermuth et al., Ch 31 , (Academic Press, 1996); A Textbook of Drug Design and Development, P. Krogsgaard- Larson and H. Bundgaard, eds. Ch 5, pgs 113 191 (Harwood Academic Publishers, 1991); Higuchi, T., et al., "Pro-drugs as Novel Delivery Systems," A.C.S. Symposium Series, Vol. 14; or in Bioreversible Carriers in Drug Design, ed. Edward B. Roche, American Pharmaceutical Association and Pergamon Press, 1987, all of which are incorporated in full by reference herein. Suitable prodrug forms of the compounds of the invention include embodiments in which one of the hydroxyl groups is substituted with C(O)OR, where R is optionally substituted alkyl, alkenyl, alkynyl, aryl, or heteroaryl. In these cases, the ester groups may be hydrolyzed in vivo e.g. in bodily fluids), releasing the active compounds.

[0098] Conjugate compounds as described herein, or for use according to the invention, can be provided alone or in combination with other compounds in the presence of a liposome, an adjuvant, or any pharmaceutically acceptable carrier, diluent or excipient, in a form suitable for administration to a subject such as a mammal, for example, humans, cattle, sheep, etc. If desired, treatment with a compound according to the invention may be combined with more traditional and existing therapies for the therapeutic indications described herein. Compounds according to the invention may be provided chronically or intermittently.“Chronic” administration refers to administration of the compound(s) in a continuous mode as opposed to an acute mode, so as to maintain the initial therapeutic effect (activity) for an extended period of time. “Intermittent” administration is treatment that is not consecutively done without interruption, but rather is cyclic in nature. The terms “administration,”“administrable,” or “administering” as used herein should be understood to mean providing a compound of the invention to the subject in need of treatment.

[0099] “Pharmaceutically acceptable carrier, diluent or excipient” includes without limitation any adjuvant, carrier, excipient, glidant, sweetening agent, diluent, preservative, dye / colorant, flavor enhancer, surfactant, wetting agent, dispersing agent, suspending agent, stabilizer, osmolality adjustment agent, solvent, or emulsifier that has been approved, for example, by the United States Food and Drug Administration or other governmental agency as being acceptable for use in humans or domestic animals.[000100] The compounds of the present invention may be administered in the form of pharmaceutically acceptable salts. In such cases, pharmaceutical compositions in accordance with this invention may comprise a salt of such a compound, preferably a physiologically acceptable salt, which are known in the art. In some embodiments, the term “pharmaceutically acceptable salt” as used herein means an active ingredient comprising conjugate compounds used in the form of a salt thereof, particularly where the salt form confers on the active ingredient improved pharmacokinetic properties as compared to the free form of the active ingredient or other previously disclosed salt form. A “pharmaceutically acceptable salt” includes both acid and base addition salts. A "pharmaceutically acceptable acid addition salt" refers to those salts which retain the biological effectiveness and properties of the free bases, which are not biologically or otherwise undesirable, and which are formed with inorganic acids such as hydrochloric acid, hydrobromic acid, sulfuric acid, nitric acid, phosphoric acid and the like, and organic acids such as amino acids, acetic acid, trifluoroacetic acid, propionic acid, glycolic acid, pyruvic acid, oxalic acid, maleic acid, malonic acid, succinic acid, fumaric acid, tartaric acid, citric acid, benzoic acid, cinnamic acid, mandelic acid, methanesulfonic acid, ethanesulfonic acid, p-toluenesulfonic acid, salicylic acid, and the like. A “pharmaceutically acceptable base addition salt” refers to those salts which retain the biological effectiveness and properties of the free acids, which are not biologically or otherwise undesirable. These salts are prepared from addition of an inorganic base or an organic base to the free acid. Salts derived from inorganic bases include, but are not limited to, the sodium, potassium, lithium, ammonium, calcium, magnesium, iron, zinc, copper, manganese, aluminum salts and the like. Preferred inorganic salts are the ammonium, sodium, potassium, calcium, and magnesium salts. Salts derived from organic bases include, but are not limited to, salts of primary, secondary, and tertiary amines, substituted amines including naturally occurring substituted amines, cyclic amines and basic ion exchange resins, such as isopropylamine, trimethylamine, diethylamine, triethylamine,tripropylamine, ethanolamine, 2-dimethylaminoethanol, 2-diethylaminoethanol, dicyclohexylamine, lysine, arginine, histidine, caffeine, procaine, hydrabamine, choline, betaine, ethylenediamine, glucosamine, methylglucamine, theobromine, purines, piperazine, piperidine, N-ethylpiperidine, polyamine resins and the like. Particularly preferred organic bases are isopropylamine, diethylamine, ethanolamine, trimethylamine, dicyclohexylamine, choline and caffeine. Thus, the term “pharmaceutically acceptable salt” encompasses all acceptable salts including but not limited to acetate, lactobionate, benzenesulfonate, laurate, benzoate, malate, bicarbonate, maleate, bisulfate, mandelate, bitartarate, mesylate, borate, methylbromide, bromide, methylnitrite, calcium edetate, methylsulfate, camsylate, mucate, carbonate, napsylate, chloride, nitrate, clavulanate, N-methylglucamine, citrate, ammonium salt, dihydrochloride, oleate, edetate, oxalate, edisylate, pamoate (embonate), estolate, palmitate, esylate, pantothenate, fumarate, phosphate / diphosphate, gluceptate, polygalacturonate, gluconate, salicylate, glutame, stearate, glycollylarsanilate, sulfate, hexylresorcinate, subacetate, hydradamine, succinate, hydrobromide, tannate, hydrochloride, tartrate, hydroxynaphthoate, teoclate, iodide, tosylate, isothionate, triethiodide, lactate, panoate, valerate, and the like. Pharmaceutically acceptable salts of the compounds of the present invention can be used as a dosage for modifying solubility or hydrolysis characteristics, or can be used in sustained release or prodrug formulations. Also, pharmaceutically acceptable salts of the compounds of this invention may include those formed from cations such as sodium, potassium, aluminum, calcium, lithium, magnesium, zinc, and from bases such as ammonia, ethylenediamine, N-methyl-glutamine, lysine, arginine, ornithine, choline, N,N’-dibenzylethylene-diamine, chloroprocaine, diethanolamine, procaine, N-benzylphenethyl-amine, diethylamine, piperazine, tris(hydroxymethyl)aminomethane, and tetramethylammonium hydroxide.[000101] Pharmaceutical formulations will typically include one or more carriers acceptable for the mode of administration of the preparation, be it by injection, inhalation, topical administration, lavage, or other modes suitable for the selected treatment. Suitable carriers are those known in the art for use in such modes of administration. Suitable pharmaceutical compositions may be formulated by means known in the art and their mode of administration and dose determined by the skilled practitioner. For parenteral administration, a compound may be dissolved in sterile water or saline or a pharmaceutically acceptable vehicle used for administration of non-water soluble compounds such as those used for vitamin K. For enteral administration, the compound may be administered in a tablet, capsule or dissolved in liquid form. The table or capsule may be enteric coated, or in a formulation for sustainedrelease. Many suitable formulations are known, including polymeric or protein microparticles encapsulating a compound to be released, ointments, gels, hydrogels, or solutions which can be used topically or locally to administer a compound. A sustained release patch or implant may be employed to provide release over a prolonged period of time. Many techniques known to skilled practitioners are described in Remington: the Science & Practice of Pharmacy by Alfonso Gennaro, 20thed., Williams & Wilkins, (2000). Formulations for parenteral administration may, for example, contain excipients, polyalkylene glycols such as polyethylene glycol, oils of vegetable origin, or hydrogenated naphthalenes. Biocompatible, biodegradable lactide polymer, lactide / glycolide copolymer, or polyoxyethylene-polyoxypropylene copolymers may be used to control the release of the compounds. Other potentially useful parenteral delivery systems for modulatory compounds include ethylene-vinyl acetate copolymer particles, osmotic pumps, implantable infusion systems, and liposomes. Formulations for inhalation may contain excipients, for example, lactose, or may be aqueous solutions containing, for example, polyoxyethylene-9-lauryl ether, glycocholate and deoxycholate, or may be oily solutions for administration in the form of nasal drops, or as a gel. The conjugate compounds or pharmaceutical compositions according to the present invention may be administered by oral or non-oral, e.g., intramuscular, intraperitoneal, intravenous, intracisternal injection or infusion, subcutaneous injection, transdermal or transmucosal routes. In some embodiments, conjugate compounds or pharmaceutical compositions in accordance with this invention or for use in this invention may be administered by means of a medical device or appliance such as an implant, graft, prosthesis, stent, etc. Implants may be devised which are intended to contain and release such compounds or compositions. An example would be an implant made of a polymeric material adapted to release the conjugate compound, or its individual components, over a period of time. The conjugate compounds may be administered alone or as a mixture with a pharmaceutically acceptable carrier e.g., as solid formulations such as tablets, capsules, granules, powders, etc. liquid formulations such as syrups, injections, etc.; injections, drops, suppositories, pessaries. In some embodiments, conjugate compounds or pharmaceutical compositions in accordance with this invention or for use in this invention may be administered by inhalation spray, nasal, vaginal, rectal, sublingual, or topical routes and may be formulated, alone or together, in suitable dosage unit formulations containing conventional non-toxic pharmaceutically acceptable carriers, adjuvants and vehicles appropriate for each route of administration.[000102] The conjugate compounds of the invention may be used to treat animals, including mice, rats, horses, cattle, sheep, dogs, cats, and monkeys. However, compounds of the invention can also be used in other organisms, such as avian species (e.g., chickens). The compounds of the invention may also be effective for use in humans. The term “subject” or alternatively referred to herein as “patient” is intended to refer to an animal, such as a vertebrate, such as a mammal, for example a human, who has been the object of treatment, observation or experiment. Accordingly, as used herein, a “subject” may be a human, nonhuman primate, rat, mouse, cow, horse, pig, sheep, goat, dog, cat, etc. The subject may be suspected of having or at risk for having a condition or disorder associated with muscle damage or may benefit from muscle repair and regeneration.[000103] An “effective amount” of a compound according to the invention includes a therapeutically effective amount or a prophylactically effective amount. A “therapeutically effective amount” refers to an amount effective, at dosages and for periods of time necessary, to achieve the desired therapeutic result, such as amelioration of muscle damage. A therapeutically effective amount of a compound may vary according to factors such as the disease state, age, sex, and weight of the individual, and the ability of the compound to elicit a desired response in the individual. Dosage regimens may be adjusted to provide the optimum therapeutic response. A therapeutically effective amount is also one in which any toxic or detrimental effects of the compound are outweighed by the therapeutically beneficial effects. A “prophylactically effective amount” refers to an amount effective, at dosages and for periods of time necessary, to achieve the desired prophylactic result, such as prevention of muscle damage. Typically, a prophylactic dose is used in subjects prior to or at an earlier stage of disease, so that a prophylactically effective amount may be less than a therapeutically effective amount. A suitable range for therapeutically or prophylactically effective amounts of a compound may be any value from 0.1 nM-0.1 M, 0.1 nM-0.05 M, 0.05 nM-15pM or 0.01 nM-10pM. In alternative embodiments, in the treatment or prevention of conditions associated with muscle damage, an appropriate dosage level will generally be about 0.01 to 1000 mg per kg subject body weight per day, and can be administered in single or multiple doses. In some embodiments, the dosage level may be about 0.1 to about 250 mg / kg per day. In some embodiments, the dosage level may be about 5 mg / kg per day. In some embodiments, the dosage level may be such that leads to sustained release of the EP4 agonist or other agent at a rate of about 5 pg / kg per day to about 50 pg / kg per day, or about 15 pg / kg per day to about 25 pg / kg per day, or any value in between or inclusive of these ranges, such as about 5, 10, 15, 20, 25, 30, 35, 40, 45 or 40 pg / kg per day. It will beunderstood that the specific dose level and frequency of dosage for any particular patient may be varied and will depend upon a variety of factors including the activity of the specific compound used, the metabolic stability and length of action of that compound, the age, body weight, general health, sex, diet, mode and time of administration, rate of excretion, drug combination, the severity of the particular condition, and the patient undergoing therapy. It is to be noted that dosage values may vary with the severity of the condition to be alleviated. For any particular subject, specific dosage regimens may be adjusted over time according to the individual need and the professional judgment of the person administering or supervising the administration of the compositions. Dosage ranges set forth herein are exemplary only and do not limit the dosage ranges that may be selected by medical practitioners. The amount of active compound(s) in the composition may vary according to factors such as the disease state, age, sex, and weight of the subject. Dosage regimens may be adjusted to provide the optimum therapeutic response. For example, a single bolus may be administered, several divided doses may be administered over time or the dose may be proportionally reduced or increased as indicated by the exigencies of the therapeutic situation. It may be advantageous to formulate parenteral compositions in dosage unit form for ease of administration and uniformity of dosage. In general, compounds of the invention should be used without causing substantial toxicity, and as described herein, the compounds exhibit a suitable safety profile for therapeutic use. Toxicity of the compounds of the invention can be determined using standard techniques, for example, by testing in cell cultures or experimental animals and determining the therapeutic index, i.e., the ratio between the LD50 (the dose lethal to 50% of the population) and the LD100 (the dose lethal to 100% of the population). In some circumstances however, such as in severe disease conditions, it may be necessary to administer substantial excesses of the compositions.[000104] In some embodiments, the conjugate compounds according to the invention are hydrolyzed at a rate that allows for dosage multiple times in a week. In some embodiments, the conjugate compounds according to the invention are hydrolyzed at a rate that allows for dosage once a week. In some embodiments, the conjugate compounds according to the invention are hydrolyzed at a rate that allows for dosage once a fortnight. Various alternative embodiments and examples of the invention are described herein. These embodiments and examples are illustrative and should not be construed as limiting the scope of the invention.[000105] The present invention will be further illustrated in the following examples.EXAMPLES[000106] Sodium (3-(4-(2-(((R,E)-4-((R)-1-(7-ethoxy-7-oxoheptyl)-5-oxopyrrolidin-2-yl)-1 ,1- difluoro-1 -phenylbut-3-en-2-yl)oxy)-2-oxoethyl)benzamido)-1-hydroxypro pane-1 ,1- diyl)bis(hydrogen phosphonate) (Mes-1022), was administered to Nakamura DMD rats (Nakamura et al., SCIENTIFIC REPORTS | 4 : 5635 | DOI: 10.1038 / srep05635). Significant blockade and reversal was noted both for bone density losses and muscle degeneration as compared to untreated control animals.[000107] Mes-1022 at 1 or 3 mg / kg was administered once weekly subcutaneously (SC) to Nakamura DMD rats from week 29-38 after birth. Once weekly subcutaneous administration of Mes-1022 at 3 mg / kg was very well tolerated and without overt side effects and significantly reversed loss of bone mineral density (Figure 1). Unexpectedly, Once weekly subcutaneous administration of Mes-1022 at 1 or 3 mg / kg also reversed loss of body weight (Figure 2A) and decline in ex vivo measured functional muscle tetanus force (Figure 2B), increased muscle mass (Figure 2C), reduced the observed degree of fibrotic deposition in muscles (Figure 2D) and reduced muscle fat (Figure 2E) when compared to paired untreated control rats and increased the number of myofibers (Figure 2F). These unanticipated effects indicate that MES-1022 can effectively block not only the bone loss and fragility associated with DMD but also block and help repair muscle degradation and fibrotic lesions associated with this phenotype while minimizing systemic side effects associated with the active EP4 agonist.[000108] Muscle regeneration and repair was observed both in muscles in close proximity to bones and also in muscles more remote from bones, indicating a more general stimulation of repair. When radiolabeled MES-1022 bearing tritium on the phenyl group of the EP4 agonist moiety:[3H]-MES-1022was administered SC to both wild type and DMD rats and tissues were analyzed for radioactivity 24 hours after dosing, the radiolabel was found to selectively accumulate (relative to blood) in bones and organs of elimination ( / .e. spleen, kidneys and liver) in both WT and DMD rats. Briefly, 6-month-old WT and DMD male rats received single subcutaneous injection of tritium-labeled MES-1022 (1 mg / Kg). Animals were sacrificed 24 hours later and tissues including whole blood, heart, and limb muscles weighed and combusted. There was relatively less radiolabel found in muscle tissues (relative to blood) in WT normal rats similar to what had been observed by Thevenin et al. (ACS Pharmacology + Translational Science, 2021 , 4 (2) 908-925). However, muscle tissues in the DMD rats preferentially accumulated radiolabel (relative to blood) (Figures 3A-B). This was true for several selected muscles, irrespective of proximity to bones and also for the heart and lungs. Thus, in diseased DMD animals, the drug selectively associates with muscle tissues and therefore is available to release the active MES-1002 agonist by slow hydrolysis in these tissues. Notably, in dystrophic diseases such as DMD, morbidity and mortality is not only associated with degeneration and failure or repair of skeletal muscles but is also associated with degeneration of cardiac and lung function. Thus, a bisphosphonate conjugated EP4 agonist prodrug, such as MES-1022 can effectively deliver the EP4 agonist to bones, stimulate growth and repair and also deliver the agonist to damaged and diseased muscle, to inhibit degeneration and stimulate repair in skeletal muscles and heart and lungs.[000109] As used herein the singular forms “a”, “and”, and “the” include plural referents unless the context clearly dictates otherwise. For example, “a compound” refers to one or more of such compounds, and equivalents thereof as known to those skilled in the art.[000110] All citations are hereby incorporated by reference.[000111] The present invention has been described with regard to one or more embodiments. However, it will be apparent to persons skilled in the art that a number of variations and modifications can be made without departing from the scope of the invention as defined in the claims. Therefore, although various embodiments of the invention are disclosed herein, many adaptations and modifications may be made within the scope of the invention in accordance with the common general knowledge of those skilled in this art. Such modifications include the substitution of known equivalents for any aspect of the invention in order to achieve the same result in substantially the same way. Numeric ranges are inclusive of the numbers defining the range. In the specification, the word “comprising” is used as an open-ended term, substantially equivalent to the phrase “including, but not limited to,” and theword “comprises” has a corresponding meaning. It is to be however understood that, where the words “comprising” or “comprises,” or a variation having the same root, are used herein, variation or modification to “consisting” or “consists,” which excludes any element, step, or ingredient not specified, or to “consisting essentially of’ or “consists essentially of,” which limits to the specified materials or recited steps together with those that do not materially affect the basic and novel characteristics of the claimed invention, is also contemplated. The elements of the present invention as described may be indicated specific embodiments, however, it should be understood that they may be combined in any manner and in any number to create additional embodiments. The variously described examples and preferred embodiments should not be construed to limit the present invention to only the explicitly described embodiments. This description should be understood to support and encompass embodiments which combine the explicitly described embodiments with any number of the disclosed and / or preferred elements. Furthermore, any permutations and combinations of all described elements in this application should be considered disclosed by the description of the present application unless the context indicates otherwise. Citation of references herein shall not be construed as an admission that such references are prior art to the present invention. All publications are incorporated herein by reference as if each individual publication was specifically and individually indicated to be incorporated by reference herein and as though fully set forth herein. The invention includes all embodiments and variations substantially as hereinbefore described and with reference to the examples and drawings

Claims

WHAT IS CLAIMED IS:1 . A method of selectively delivering an EP4 agonist or related compound to a damaged muscle, the method comprising administering a bisphosphonate-EP4 agonist or related compound to a subject in need thereof, wherein the bisphosphonate-EP4 agonist or related compound is selectively delivered to the damaged muscle.

2. The method of claim 1 wherein the method comprises treating or preventing damage to a muscle, or reversing or repairing a damage to a muscle.

3. A method of treating or preventing damage to a muscle, or reversing or repairing a damage to a muscle, the method comprising administering a bisphosphonate- EP4 agonist or related compound to a subject in need thereof.

4. The method of any one of claims 1 to 3 wherein the muscle is a skeletal muscle, a smooth muscle or a cardiac muscle, a muscle associated with the lungs, a muscle associated with blood vessels, or a muscle associated with kidney or kidney vasculature.

5. The method of any one of claims 1 to 3 wherein the muscle is damaged by injury, overuse, or due to a disease or condition that includes muscle damage.

6. The method of claim 5 wherein the disease or condition that includes muscle damage is a cardiac disorder, a vascular system disorder, inflammatory bowel disease, a muscular dystrophy, asthma, pulmonary fibrosis, asthma, chronic obstructive pulmonary disease (COPD), or a fibrotic kidney disease.

7. The method of claim 6 wherein the cardiac disorder is a fibrotic cardiac disease or is calcification of a cardiac valve.

8. The method of claim 6 wherein the vascular system disorder is a vascular lesion associated with calcification.

9. The method of claim 6 wherein the muscular dystrophy is Duchenne Muscular Dystrophy.

10. The method of any one of claims 1 to 9 wherein the bisphosphonate- EP4 agonist is a compound according to Formula I or a pharmaceutically acceptable salt thereof:Formula I wherein:X is -CH2-, -S-, -O-, or -NH-;Y is COOR', optionally substituted tetrazole, or C(O)NHSO2R;Z is OH or H;R is optionally substituted lower alkyl or optionally substituted aryl; n is 1 , 2, or 3; m is 0, 1 , 2, 3, 4, 5, or 6; q is 1 , or 2;Ri is independently H or halogen;Ar is aryl, substituted aryl, or heteroaryl;R3is each independently H, OR', halogen, CN, or C(0)R';R' is each independently H or lower alkyl, or two R's may form a ring of up to 6 carbons; and is a double or single bond.11 . The method of claim 10 wherein the EP4 agonist-bisphosphonate conjugate compound is: Sodium (4-(4-(2-(((R,E)-4-((R)-1-(7-ethoxy-7-oxoheptyl)-5-oxopyrrolidin-2-yl)-1 ,1-difluoro-1-phenylbut-3-en-2-yl)oxy)-2-oxoethyl)benzamido)-1-hydroxybutane-1 ,1-diyl)bis(hydrogen phosphonate);Sodium (3-(4-(2-(((R,E)-4-((R)-1-(7-ethoxy-7-oxoheptyl)-5-oxopyrrolidin-2-yl)-1 ,1-difluoro-1- phenylbut-3-en-2-yl)oxy)-2-oxoethyl)benzamido)-1 -hydroxypropane-1 ,1 -diyl)bis(hydrogen phosphonate);Sodium (6-(4-(2-(((R,E)-4-((R)-1-(7-ethoxy-7-oxoheptyl)-5-oxopyrrolidin-2-yl)-1 ,1-difluoro-1- phenylbut-3-en-2-yl)oxy)-2-oxoethyl)benzamido)-1-hydroxyhexane-1 ,1-diyl)bis(hydrogen phosphonate);Sodium (4-(3,5-bis(2-(((R,E)-4-((R)-1-(7-ethoxy-7-oxoheptyl)-5-oxopyrrolidin-2-yl)-1 ,1-difluoro-1- phenylbut-3-en-2-yl)oxy)-2-oxoethyl)benzamido)-1-hydroxybutane-1 ,1-diyl)bis(hydrogen phosphonate);Sodium (4-(4-(2-(((R,E)-4-((R)-1-(6-carboxyhexyl)-5-oxopyrrolidin-2-yl)-1 ,1-difluoro-1-phenylbut-3- en-2-yl)oxy)-2-oxoethyl)benzamido)-1-hydroxybutane-1 ,1-diyl)bis(hydrogen phosphonate);Sodium (3-(4-(2-(((R,E)-4-((R)-1-(6-carboxyhexyl)-5-oxopyrrolidin-2-yl)-1 ,1-difluoro-1-phenylbut-3- en-2-yl)oxy)-2-oxoethyl)benzamido)-1 -hydroxypropane-1 ,1-diyl)bis(hydrogen phosphonate);Sodium (6-(4-(2-(((R,E)-4-((R)-1-(6-carboxyhexyl)-5-oxopyrrolidin-2-yl)-1 ,1-difluoro-1-phenylbut-3- en-2-yl)oxy)-2-oxoethyl)benzamido)-1-hydroxyhexane-1 ,1-diyl)bis(hydrogen phosphonate); orSodium (4-(3,5-bis(2-(((R,E)-4-((R)-1-(6-carboxyhexyl)-5-oxopyrrolidin-2-yl)-1 ,1-difluoro-1- phenylbut-3-en-2-yl)oxy)-2-oxoethyl)benzamido)-1-hydroxybutane-1 ,1-diyl)bis(hydrogen phosphonate).

12. The method of claim 10 wherein the EP4 agonist-bisphosphonate conjugate compound is:C3 (MES-1007) MES-102213. The method of any one of claims 1 to 9 wherein the EP4 agonist is a compound comprising a hydroxyl group at a position equivalent to C-15 of prostaglandin E2.

14. The method of any one of claims 1 to 9 wherein the EP4 agonist is: prostaglandinprostaglandinAE-1-329:pCompound A:Compound B:, wherein in Compound B, a dashed line indicates the presence or absence of a bond, A is optionally substituted phenyl, X is CH2, O or S, Y is OR1or N R1R2and R1and R2are independently H or Ci-6alkyl.

15. Use of a bisphosphonate-EP4 agonist or related compound for selective delivery of an EP4 agonist or related compound to a damaged muscle.

16. Use of a bisphosphonate-EP4 agonist or related compound for treating or preventing damage to a muscle, or for reversing or repairing a damage to a muscle.

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