Bone-targeted canonical notch inhibitor

Abstract

Disclosed herein are bone-targeted Notch inhibitors joined to a targeting group where the Notch inhibitor moiety has an oxydiaryl structure. Also disclosed are uses thereof, including methods for inhibiting growth or proliferation of bone tumor cells.

Description

[0001] BONE-TARGETED CANONICAL NOTCH INHIBITOR

[0002] CROSS-REFERENCE TO RELATED APPLICATIONS

[0003] This application claims benefit of priority to U.S. Patent Application Ser. No. 63 / 515,576, filed July 25, 2023, the contents of which is incorporated by reference in its entirety.

[0004] STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH

[0005] This invention was made with government support under R37CA251763 awarded by National Institutes of Health. The government has certain rights in the invention.

[0006] BACKGROUND OF THE INVENTION

[0007] Bone is a primary site of metastasis. In addition, several less common, but devastating cancers develop in bone (sarcomas, leukemia, multiple myeloma). The bone provides a rich soil for the cancer to thrive, and cancer that grow in bone are typically incurable. Notch is a highly conserved key oncogenic pathway mediating cell communication in the tumor microenvironment. Notch signaling is involved in tumor initiation, progression, bone destruction, and resistance to therapies. The multifunctional role of Notch communication in cancer provides a strong rationale to target this pathway for therapeutic purposes. Signaling inhibition downstream of the four Notch receptors with y-secretase inhibitors (GSI) has been used to inhibit Notch in multiple myeloma. GSIs decrease tumor growth and mitigate the bone disease in animal models of cancer. Despite these promising results, the use of GSIs in the clinic has been prevented because of undesirable, dose-limiting severe toxicities, particularly gastrointestinal toxicity, derived from the systemic inhibition of Notch in different tissues. 6-(4-(tert-butyl)phenoxy)pyri din-3 -amine, also known as CB-103, is a small molecule capable of preventing the formation of the transcriptional activation complex known as NICD-CSL. While effective, in preventing tumor growth, systemic administration of CD-103 results in gut toxicity. A new approach is needed to reduce undesired side-effects of systemic Notch inhibition while retaining the ability to block Notch communication.

[0008] SUMMARY

[0009] Disclosed herein are bone-targeted Notch inhibitors joined to a targeting group where the Notch inhibitor moiety has an oxydiaryl structure. The compound comprises a bone-targeting group, a notch inhibitor moiety, and a linker L therebetween. The compound includes the notch inhibitor moiety having the formula where R is selected from the group consisting of tert-butyl, tert-pentyl, cyclohexyl, (3r,5r,7r)- adamantan-l-yl, and wherein W is selected from the group consisting of N, CH, or CF. The bone targeting group comprises a bis-phosphonate group.

[0010] Further disclosed herein is a compound having Formula (I) (I), or a pharmaceutically acceptable salt thereof, where Ri is H, alkyl, or aryl, R2 is tert-butyl, tert- pentyl, cyclohexyl, or (3r,5r,7r)-adamantan-l-yl, and L is a saturated or unsaturated alkyl or a polyethylene glycol optionally substituted with one or more substituents selected from alkyl, haloalkyl, aryl, heteroaryl, heterocyclic, cycloalkyl, and any combination thereof.

[0011] Further disclosed herein is a compound having Formula (II), where Ri is selected from the group consisting of H, alkyl, or ary, R3 is selected from the group consisting of H, CF3, t-Bu, cyclopropyl, alkyl, aryl, heteroaryl, heterocyclic, cycloalkyl, n is any number between 0 and 10, X is any of O, N, S, or CH2, Y is any of O, N, S, CH2, and Z is any of O, NH, S.

[0012] Further disclosed herein is a compound having Formula (III),

[0013] Further disclosed herein is a compound having Formula (IV),

[0014] Further disclosed herein is a compound having Formula (V),

[0015] Further disclosed herein is a compound having Formula (VI), where Ri is selected from the group consisting of H, alkyl, or aryl, R3 is selected from the group consisting of H, CF3, t-Bu, cyclopropyl, alkyl, aryl, heteroaryl, heterocyclic, cycloalkyl, n is any integral number between 0 and 10, A is selected from the group consisting of alkyl, alkenyl, alkynyl, phenyl, O, N, S, X is selected from the group consisting of O, N, S, or CH2, and Y is selected from the group consisting of O, N, S, CH2.

[0016] Further disclosed herein is a compound having Formula (VII), where Ri is selected from the group consisting of H, alkyl, or aryl, R3 is selected from the group consisting of H, CF3, t-Bu, cyclopropyl, alkyl, aryl, heteroaryl, heterocyclic, cycloalkyl, m is any integral number between 0 and 10, X is selected from the group consisting of O, N, S, or CH2, and Y is selected from the group consisting of O, N, S, CH2.

[0017] Further disclosed herein is a compound having Formula (VIII), where Ri is selected from the group consisting of H, alkyl, or aryl, B is selected from the group consisting of CH or N, X is selected from the group consisting of O, N, S, or CH2, and Y is selected from the group consisting of O, N, S, CH2.

[0018] Further disclosed herein is a compound having Formula (IX), where Ri is selected from the group consisting of H, alkyl, or aryl, C is selected from the group consisting of CH2, NH, NMe, O, or S, D is any integral number between 0 and 4, X is selected from the group consisting of O, N, S, or CH2, and Y is selected from the group consisting of O, N, S, CH2.

[0019] Further disclosed herein is a method for the treatment of bone loss comprising administering an effective amount of the compound to a subject in need thereof. The method includes bone tumor growth associated with cancer metastasis, sarcoma, leukemia, multiple myeloma.

[0020] Further disclosed herein is a method for reducing or inhibiting bone tumor growth comprising administering an effective amount of the compound to a subject in need thereof. The method includes bone tumor growth associated with cancer metastasis, sarcoma, leukemia, multiple myeloma. Further disclosed herein is a method of inhibiting the growth or proliferation of bone tumor cells comprising contacting the bone tumor cells with the compound or a pharmaceutically acceptable salt thereof.

[0021] Further disclosed herein is a method of inducing apoptosis of bone tumor cells comprising contacting the bone tumor cells with the compound or a pharmaceutically acceptable salt thereof.

[0022] Further disclosed herein is a method of inhibiting a CSL-NICD gene transcription complex in bone tumor cells comprising contacting the bone tumor cells with the compound or a pharmaceutically acceptable salt thereof.

[0023] Further disclosed herein is a method of downregulating the expression of Rankl in bone tumor cells comprising contacting the bone tumor cells with the compound or a pharmaceutically acceptable salt thereof.

[0024] Further disclosed herein is a method of downregulating the expression of HES genes in bone tumor cells comprising contacting the bone tumor cells with the compound or a pharmaceutically acceptable salt thereof.

[0025] Further disclosed herein is a method of downregulating the expression of HEY genes in bone tumor cells comprising contacting the bone tumor cells with the compound or a pharmaceutically acceptable salt thereof.

[0026] The disclosed methods include bone tumor cells are multiple myeloma cells. The contacting step is performed in vitro or ex vivo. The contacting step is performed in vivo.

[0027] The compound is the compound any of the compounds described as Formula (I)-(IX).

[0028] BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Non-limiting embodiments of the present invention will be described by way of example with reference to the accompanying figures, which are schematic and are not intended to be drawn to scale. In the figures, each identical or nearly identical component illustrated is typically represented by a single numeral. For purposes of clarity, not every component is labeled in every figure, nor is every component of each embodiment of the invention shown where illustration is not necessary to allow those of ordinary skill in the art to understand the invention.

[0030] Figure 1 shows proliferation (number of viable cells), cell death (number of dead cells), and apoptosis (%) of OPM-2 human multiple myeloma cells at 72 h after treating with either GSL XX (CAS No. 209984-56-5) or CB-103. Figure 2 shows the gene expression of Notch targeted HES and HEY genes in OPM-2 human multiple myeloma cells treated with CB-103.

[0031] Figure 3 shows the proliferation (number of viable cells), cell death (number of dead cells, %) of JJN3 human multiple myeloma cells at 72 h after treating with either GSI or CB-103.

[0032] Figure 4 shows gene expression of Notch targeted genes (HES and HEY) in JJN3 human multiple myeloma cells treated with either CB-103 or GSI at a dosage of 15pM.

[0033] Figure 5 shows Notch targeted gene expression (HES and Rankl) in ex vivo bone organ cultures dosed with 20pM of one of vehicle, BPTB, BPTF, BT, CB-103, BPA-CB103, BPTB- CB103, BPTF-CB103, or BT-GSI.

[0034] Figure 6 shows cryosections of TNR Notch reporter animals treated with CB-103 and a control. Magnification = 20x; Dose = 20pM / day for 3 days (CB-103) Samples were stored in PFA (2 days) followed by decalcification for 6 days and preserved at 30% sucrose solution (Overnight). Samples were embedded in OCT solution and sliced (lOpm / slice) using cryostat. This image shows the ability of CB-103 to decrease Notch signaling in bone tissues, including cells living in the mineralized tissue.

[0035] Figure 7 shows the effects of bone-targeted CB-103 compounds on Notch signaling in MM cell lines, specifically JJN3 cells and 5TGM1 cells.

[0036] Figure 8 shows the lack of effects of bone-targeting moieties on Notch signaling in MM cell lines, specifically JJN3 cells and 5TGM1 cells.

[0037] Figure 9 shows data demonstrating that bone-targeted CB-103 conjugates, but not bone- targeting moieties, decrease proliferation and induce cell death in myeloma cell lines, specifically JJN3 cells and 5TGM1 cells.

[0038] Figure 10 shows that BPA-CB103 mitigates MM-induced bone loss. Percent BV / TV means the percentage of mineralized bone volume versus the total volume of the skeletal sample.

[0039] DETAILED DESCRIPTION OF THE INVENTION

[0040] Disclosed herein is a compound including a Notch inhibitor moiety joined to a targeting group via a linker. The targeting group is included to direct the Notch inhibitor moiety to a specific, desired site, for example to a particular organ or tissue type within a body. Upon administration, the compound can localize at the targeted site, thus avoiding toxicity in other tissues and reducing undesirable side effects. Suitably, a semilabile linkage can join the Notch inhibitor moiety to the linker, such that a Notch inhibitor can be released from the compound once the compound is localized in the desired region.

[0041] Notch inhibitor moiety

[0042] In some examples, the Notch inhibitor moiety has an oxy diaryl structure with the following general formula: where R2 can be a hydrophobic group, for example tert-butyl, tert-pentyl, cyclohexyl, or (3r,5r,7r)- adamantan-l-yl. The R2 group can assist binding of the compound to the NICD-CSL complex. Furthermore, W can be N, CH, or CF. These structural analogues can be included in the compound as the Notch inhibitor moiety. Exemplary Notch inhibitor moieties include:

[0043] Bone-targeting group

[0044] In some embodiments, the targeting group can be a bone-targeting group. The bone- targeting group can be a functional group known to have a high affinity for finding to the surface of bone or intercalating into bone. In one example as shown in Formula I, the bone-targeting group can be a bisphosphonate. Bisphosphonates have a high affinity for the hydroxyapatite mineral found in bone, and are well known to bind by an electrostatic interaction between negatively charged oxygens of the bisphosphonate and positively charged calcium ions in the surface of the bone.

[0045] As shown in Formula I, Ri of the bisphosphonate can be H, an alkyl (e.g., H, CH3, ethyl, propyl, isopropyl, butyl), or an aryl (e.g. phenyl). If Ri is a carbon-containing group (i.e., not H), it must be processed or cleaved from the bisphosphonate to form the tetra acid form where Ri is H (e.g., by hydrolysis, or enzymatic activity) before the compound can bind to the surface of a bone.

[0046] In some embodiments, the bone-targeting group can be a modified bisphosphonate. For example, the bone-targeting group can be etidronate, tiludronate, clodronate, alendronate, pamidronate, ibandonate, zoledronate, risedronate, minodronate, phytic acid, or a derivative thereof, In other examples, the bone-targeting group can be a peptide rich in negatively charged amino acids (e.g., aspartate, glutamate). Additionally and alternatively, tetracyclines are also known to have a high affinity for bone, and may be used as the bone-targeting group.

[0047] Semi-labile Linkage

[0048] The semi labile linkage connects the Notch inhibitor moiety to the targeting group. The semi labile linkage can be selected to control of the rate at which the Notch inhibitor moiety is cleaved from the compound to release the Notch inhibitor. In other words, the semi labile linkage includes a labile bond that is stable enough to hold the compound together just long enough for the compound to accumulate at the site of interest. Once the compound has accumulated, the labile bond breaks and releases the Notch inhibitor. In some embodiments, the semi labile linkage can be a carbamate. Other types of bonds are contemplated for the semi labile linkage, for example dithiocarbamate, disulfide, ester, or amide. In some embodiments, the semi labile linkage can be cleaved by hydrolysis. In other embodiments, the semi labile linkage can be cleaved by an enzyme. Based on the release rate, or the rate at which the Notch inhibitor is released from the compound, the dosage of the compound can be adjusted.

[0049] Linker

[0050] The linker is adjacent to the semi labile linkage and thus connects the Notch inhibitor moiety to the targeting group. Because it is connected to the semi labile linkage, the properties of the linker (e.g., electron withdrawing or electron donating) can influence the lability of the semi labile linkage, thus allowing the rate of delivery of the Notch inhibitor to be tuned.

[0051] In some examples, the compound can have Notch inhibitor moiety, a substituted alkyl linker, and a bisphosphonate targeting group as exemplified by Formula II. (II).

[0052] In Formula II examples, the alkyl portion of the linker can have an n value between 0 and 10. The substituent R3 can be H, CF3, t-Bu, cyclopropyl, alkyl, aryl, heteroaryl, heterocycle, or cycloalkyl. The linker may be optically pure or a racemic mixture. Furthermore, the semi labile linkage can include any combination of X, Y, and Z, where X and Y can independently be O, N, S, or CH2, and Z can be any one of O, NH, or S. For example, Formula I includes a carbamate linkage.

[0053] Specific examples of Formula II include: In some examples, the compound can have Notch inhibitor moiety, an unsaturated or heteroalkyl linker, and a bisphosphonate targeting group as exemplified by Formula VI.

[0054] In Formula VI examples, the alkyl portion of the linker can have an n value between 0 and 10. The linker can further include A, where A is at least one double bond, at least one triple bond, at least one aryl group, or at least one heteroatom, (e.g., O, N, or S). The substituent R3 can be H, CF3, t-Bu, cyclopropyl, alkyl, aryl, heteroaryl, heterocycle, or cycloalkyl. The linker may be optically pure or a racemic mixture.

[0055] In some examples, the compound can have a Notch inhibitor moiety, a poly ether linker, and a bisphosphonate targeting group as exemplified by Formula VIE

[0056] The linker can include a polyether such as polyethylene glycol (PEG) or polypropylene glycol. The repeating alkyl ether portion of the linker can have an m value between 0 and 10. The linker can be selected for control of the solubility, for example including a PEG group can improve aqueous solubility. The linker can be selected for stability of the compound in aqueous solutions. The linker can be selected for stability of the compound in buffered solutions or biological conditions, such as in the bloodstream.

[0057] In some examples, the compound can have a Notch inhibitor moiety, a cyclic linker, and a bisphosphonate targeting group as exemplified by Formula VIII, The cyclic linker can include at least one cycle incorporated into the linker backbone as shown. In Formula VIII examples, each instance of B can independently be CH orN, or any combination thereof.

[0058] In some examples, the compound can have a Notch inhibitor moiety, a linker, and a bisphosphonate targeting group as exemplified by Formula IX,

[0059] The linker can include at least one component C incorporated into the linker backbone as shown, where C can be CH2, or a heteroatom, e.g., NH, NMe. O, or S. The linker can further include an optional cyclic component defined by D, where D can be any number between 0 and

[0060] Specific examples of bone-targeted Notch inhibitors according to Formulas I-IX are:

[0061]

[0062]

[0063]

[0064] Methods for treating subjects with the compounds disclosed herein are provided. Suitably, the methods for treating a subject comprise administering to the subject an effective amount of one or more compounds or pharmaceutically acceptable salts thereof, or a pharmaceutical composition comprising the effective amount of one or more compounds or pharmaceutically acceptable salts thereof. As used herein, a “subject” may be interchangeable with “patient” or “individual” and means an animal, which may be a human or non-human animal, in need of treatment. In particular embodiments, the subject is a human subject.

[0065] As used herein, the terms “treating” or “to treat” each mean to alleviate symptoms, eliminate the causation of resultant symptoms either on a temporary or permanent basis and / or to prevent or slow the appearance or to reverse the progression or severity of resultant symptoms of the named disease or disorder. As such, the methods disclosed herein encompass both therapeutic and prophylactic administration. In some embodiments, the subject is responsive to therapy with one or more of the compounds disclosed herein in combination with one or more additional therapeutic agents.

[0066] As used herein the term “effective amount” refers to the amount or dose of the compound that provides the desired effect. In some embodiments, the effective amount is the amount or dose of the compound, upon single or multiple dose administration to the subject, which provides the desired effect in the subject under diagnosis or treatment. The compounds may be administered to a subject in an effective amount in such that the transcriptional activation complex known as NICD-CSL, is inhibited. Suitably, the desired effect may be slowing progression of bone tumor growth, halting of bone tumor growth, reversing of bone tumor growth, or reducing of bone tumor growth. In some embodiments, the effective amount of the compound results in slowing of bone tumor growth, reducing of bone tumor growth, or increasing apoptosis in bone tumors. In still other embodiments, the effective amount of the compound results in reduction of bone loss or osteoporosis. In still other embodiments, the effective amount of the compound results in reduction of non-neoplastic skeletal disease characterized by high bone resorption.

[0067] An effective amount can be readily determined by those of skill in the art, including an attending diagnostician, by the use of known techniques and by observing results obtained under analogous circumstances. In determining the effective amount or dose of compound administered, a number of factors can be considered by the attending diagnostician, such as: the species of the subject; its size, age, and general health; the degree of involvement or the severity of the disease or disorder involved; the response of the individual subject; the particular compound administered; the mode of administration; the bioavailability characteristics of the preparation administered; the dose regimen selected; the use of concomitant medication; and other relevant circumstances.

[0068] A “subject in need of treatment” may include a subject having a disease, disorder, or condition that may be characterized by a disease associated with or that contributes to the development or progression of bone loss or bone tumors. The compound can be administered systemically as a pharmaceutical composition. Pharmaceutical compositions comprising the compound or pharmaceutically acceptable salt thereof may be adapted for administration by any appropriate route, for example by the oral (including buccal or sublingual), rectal, nasal, topical (including buccal, sublingual or transdermal), vaginal or parenteral (including subcutaneous, intramuscular, intravenous or intradermal) route. Such formulations may be prepared by any method known in the art of pharmacy, for example by bringing into association the active ingredient with the carrier(s) or excipient(s).

[0069] According to an aspect as disclosed herein, a method for treatment of bone loss may include administering an effective amount of the compound or a pharmaceutically acceptable salt thereof to a subject in need thereof. The subject in need of treatment may have bone loss associated with metastasis of cancer from another part of the body, such as breast, kidney, lung, lymphoma, thyroid, or prostate cancer. In some embodiments, the bone tumor growth may be associated with sarcoma. In other embodiments, the bone tumor growth may be associated with leukemia. In further embodiments, the bone tumor growth may be associated with multiple myeloma. In other embodiments, the bone tumor growth may be associated with radiation exposure. In some embodiments, the bone tumor growth may be associated with a genetic predisposition.

[0070] According to an aspect as disclosed herein, a method for reducing bone tumor growth may include administering an effective amount of the compound or a pharmaceutically acceptable salt thereof to a subject in need thereof. The subject in need of treatment may have bone tumor growth associated with metastasis of cancer from another part of the body, such as breast, kidney, lung, lymphoma, thyroid, or prostate cancer. In some embodiments, the bone tumor growth may be associated with sarcoma. In other embodiments, the bone tumor growth may be associated with leukemia. In further embodiments, the bone tumor growth may be associated with multiple myeloma. In other embodiments, the bone tumor growth may be associated with radiation exposure. In some embodiments, the bone tumor growth may be associated with a genetic predisposition. The subject in need of treatment may have abnormal bone resorption due to osteoporosis, bone loss, or other disorder.

[0071] According to an aspect as disclosed herein, a method of inhibiting the growth or proliferation of bone tumor cells may include contacting the bone tumor cells with the targeted compound. Cell growth refers to the increase in cell size or mass accumulation. Cell proliferation is the process of generating an increased number of cells through cell division. The bone tumor cells may be, for example, JJN3 human multiple myeloma cells, or OPM-2 human multiple myeloma cells. The bone tumor cells may be contacted in vitro or in vivo with the compound. In some embodiments, a method of inducing apoptosis of bone tumor cells may include contacting bone tumor cells with the compound. As used herein, apoptosis is the programmed death of cells which typically occurs as a normal and controlled part of an organism's growth or development.

[0072] Notch signaling is a highly conserved mechanism for communication between adjacent cells and regulates many aspects of cancer biology. For example, multiple myeloma (MM) cells use Notch to communicate with adjacent MM cells and other cells in a tumor niche. Activation of Notch stimulates MM growth, increases osteoclastogenesis and bone destruction, and contributes to the development of drug resistance. Further, studies found that the effects of the Notch pathway vary among osteosarcoma cell lines, including effects on proliferation, migration and invasion, drug resistance, and cancer stem cell characteristics. In addition, Notch signaling has an important impact on the microenvironment of osteosarcoma via modulating immune function, tumor angiogenesis, and osteogenic differentiation, which indirectly affect the biological behavior of osteosarcoma. Thus, Notch signaling is an important target for the treatment of MM and osteosarcoma. According to an aspect as disclosed herein, a method of inhibiting the CSL-NICD gene transcription complex in bone tumor cells may include contacting the bone tumor cells with the compound. Example 6 shows in vitro testing results.

[0073] Rankl is a member of the tumor necrosis factor (TNF) superfamily. Rankl is expressed in osteoblasts and plays an important role in bone metabolism. This surface-bound molecule can activate osteoclasts, which are involved in bone resorption. Rankl can contribute to bone loss in conditions involving inflammation such as in lesions caused by cancer, e.g., multiple myeloma. In some embodiments, a method of downregulating the expression of Rankl in bone tumor cells may include contacting the bone tumor cells with the compound. Test results in Example 6 show that Rankl can be downregulated by BPA-CB103, BPTB-CB103, and BPTF-CB103.

[0074] HES / HEY genes encode a family of basic helix-loop-helix (bHLH) transcription factors. HES / HEY proteins are direct targets of the Notch signaling pathway and play an important role in development of the nervous system, blood vessel and heart. Aberrant Notch-Hes 1 axis is presented in cancer stem cells, such as glioblastoma, breast cancer, pancreatic cancer, and osteosarcoma. The inhibition of the Notch signaling pathway can reverse cancer cell survival and induce apoptosis. If the Notch signaling pathway is blocked by an inhibitor, the population of cancer stem cells can be depleted.

[0075] A method of downregulating the expression of HES gene in multiple myeloma cells, may include contacting the multiple myeloma cells with the compound. Similarly, a method of downregulating the expression of HEY gene in multiple myeloma cells, may include contacting the multiple myeloma cells with the compound. Test results in Example 6 show that HEY1 and HES1 can be downregulated by BPA-CB103, BPTB-CB103, and BPTF-CB103.

[0076] A method of downregulating the expression of HES gene in a subject may include administering a dose of at least one of the compounds BPA-CB103, BPTB-CB103, and BPTF- CB103 to the subject. Similarly, a method of downregulating the expression of HEY gene in multiple myeloma cells, may include contacting the multiple myeloma cells with at least one of the compounds BPA-CB103, BPTB-CB103, and BPTF-CB103. Test results in Example 10 show that HEY1 can be downregulated by BPA-CB103. A method of mitigating bone loss in a subject may include administering a dose of BPA- CB103, BPTB-CB103, and BPTF-CB103. Test results in Example 10 show that mitigating bone loss in a subject can be achieved by administering BPA-CB103.

[0077] Benefits

[0078] There are no FDA-approved therapies to inhibit Notch signaling. The strategy of targeting Notch signaling in the bone can apply to primary, hematological, and metastatic cancers. Targeted inhibition of Notch signaling to bone microenvironment with compounds is a promising therapeutic approach with dual anti-tumor and anti-resorptive properties, enabling simultaneous inhibition of tumor growth and prevention of bone destruction in cancers that grow in bone. The compounds disclosed herein are effective in inhibiting Notch signaling in cancer cells and the conjugates generated are capable of inhibiting this pathway in bone tissue. The new chemical entities disclosed herein are stable in the bloodstream and transport to the skeleton within minutes to hours. The bone-targeting group allows the compounds to be delivered in particularly high concentrations wherever there is high bone loss or bone turnover, a characteristic of bone diseases. In the presence of such bone metabolism high local concentrations of potent Notch signaling inhibitors can be released. The linker substitutions allow for different release rates. Further, because the Notch inhibitor is targeted to the bone and there can be different release rates, lower doses may be administered. The compounds disclosed herein are more stable in the bloodstream and offer safety advantages over other Notch inhibitors. Because the compounds are tissue-specific and selectively block Notch signaling in bone, there are lower safety concerns elsewhere in the body. For example the compounds should lack gut toxicity and circumvent the undesirable side effects that limit the clinical use of Notch inhibitors. Due to the anti -resorptive activity of these bone-targeted compounds, they can also be used to treat osteoporosis and other non-neoplastic skeletal disease characterized by high bone resorption

[0079] Miscellaneous

[0080] Unless otherwise specified or indicated by context, the terms “a”, “an”, and “the” mean “one or more.” For example, “a molecule” should be interpreted to mean “one or more molecules.”

[0081] As used herein, “about”, “approximately,” “substantially,” and “significantly” will be understood by persons of ordinary skill in the art and will vary to some extent on the context in which they are used. If there are uses of the term which are not clear to persons of ordinary skill in the art given the context in which it is used, “about” and “approximately” will mean plus or minus <10% of the particular term and “substantially” and “significantly” will mean plus or minus >10% of the particular term.

[0082] As used herein, the terms “include” and “including” have the same meaning as the terms “comprise” and “comprising.” The terms “comprise” and “comprising” should be interpreted as being “open” transitional terms that permit the inclusion of additional components further to those components recited in the claims. The terms “consist” and “consisting of’ should be interpreted as being “closed” transitional terms that do not permit the inclusion additional components other than the components recited in the claims. The term “consisting essentially of’ should be interpreted to be partially closed and allowing the inclusion only of additional components that do not fundamentally alter the nature of the claimed subject matter.

[0083] All methods described herein can be performed in any suitable order unless otherwise indicated herein or otherwise clearly contradicted by context. The use of any and all examples, or exemplary language (e.g., “such as”) provided herein, is intended merely to better illuminate the invention and does not pose a limitation on the scope of the invention unless otherwise claimed. No language in the specification should be construed as indicating any non-claimed element as essential to the practice of the invention.

[0084] All references, including publications, patent applications, and patents, cited herein are hereby incorporated by reference to the same extent as if each reference were individually and specifically indicated to be incorporated by reference and were set forth in its entirety herein.

[0085] Preferred aspects of this invention are described herein, including the best mode known to the inventors for carrying out the invention. Variations of those preferred aspects may become apparent to those of ordinary skill in the art upon reading the foregoing description. The inventors expect a person having ordinary skill in the art to employ such variations as appropriate, and the inventors intend for the invention to be practiced otherwise than as specifically described herein. Accordingly, this invention includes all modifications and equivalents of the subject matter recited in the claims appended hereto as permitted by applicable law. Moreover, any combination of the above-described elements in all possible variations thereof is encompassed by the invention unless otherwise indicated herein or otherwise clearly contradicted by context. EXAMPLES

[0086] The following Examples are provided to demonstrate and further illustrate certain embodiments and aspects of the present invention and is not to be construed as limiting the scope of the invention. The statements provided in the Example are presented without being bound by theory.

[0087] Example 1

[0088] The synthesis of 6-(4-( / ert-butyl)phenoxy)pyridin-3-amine (CB-103) is shown in Scheme 1.

[0089] Scheme 1

[0090] The synthesis of 2-(4-(te / 7-butyl)phenoxy)-5-nitropyridine in Step 1 of Scheme 1 is shown below in more detail.

[0091] An oven dried round bottom flask was charged with a solution of 2-chloro-5-nitropyridine in anhydrous DMF (10 g, 0.07 moles in 120 mL). Freshly activated potassium carbonate (14.5 g, 0.105 moles) and 4-( / c / 7-butyl)phenol (12 g, 0.077 moles) were added sequentially and the contents were heated at 60°C for 3h. The reaction mixture was diluted with water (600 mL) and the aqueous layer was extracted with diethyl ether (5 x 100 mL). The combined organic layer was washed with brine (2 x 100 mL), dried over anhydrous sodium sulphate, filtered, and concentrated under reduced pressure. The crude mixture was purified by column chromatography on silica (0 % to 5 % ethyl acetate in n-hexanes) to yield 16.96 g (89%) of 2-(4-(tert-butyl)phenoxy)-5- nitropyridine as off white solid. Rf (Silica) 0.7 (20 % ethyl acetate in n-hexanes, UV & KMnO4)1H-NMR (400 MHz, CD3OD) ^ 8.96 (d, J = 2.8 Hz, 1H), 8.54 (dd, J1= 5.2 Hz, J2= 8.8 Hz, 1H), 7.47 (d, J = 8.8 Hz, 2H), 7.11 – 6.98 (m, 3H), 1.35 (s, 9H). The synthesis of 6-(4-(tert-butyl)phenoxy)pyridin-3-amine for Step 2 of Scheme 1 is shown below. An oven dried round bottom flask was charged with a solution of 2-(4-(tert- butyl)phenoxy)-5-nitropyridine in ethyl acetate (4.5 g, 16.52 mmol in 20 mL). Methanol (20 mL) and palladium on carbon (0.45g, 0.422 mmol, 10 %) were sequentially. The reaction mixture was run in an atmosphere of hydrogen (1 atm) for 2 days. The contents were carefully filtered over celite and the filtrate was concentrated under reduced pressure. The crude mixture was purified by column chromatography on silica (50 % to 100 % n-hexanes in diethyl ether) to yield 3.849 (96%) 6-(4-(tert-butyl)phenoxy)pyridin-3-amine as off white solid. (Note: The product is light sensitive. Hence concentrated and stored in the absence of light). Rf (Silica) 0.1 (25 % ethyl acetate in n-hexanes, UV & KMnO4)1H-NMR (400 MHz, CD3OD) ^ 7.62 (d, J = 2.8 Hz, 1H), 7.37 (d, J = 8.4 Hz, 2H), 7.20 (dd, J1 = 5.2 Hz, J2 = 8.4 Hz, 1H), 6.87 (d, J = 12 Hz, 2H), 6.71 (d, J = 8.4 Hz, 1H), 1.31 (s, 9H). Example 2 BPA-CB103 (C21H30BrN3O10P2) has a molecular weight = 626.33 g / mol. This conjugate is formed by linking a bisphosphonate bone targeting to an amino pyridine functional group from the CB-103 through an aryl carbamate linkage. BPA-CB103 has the formula . yl)carbamoyl)oxy)butanamido)methylene)bis(phosphonic acid), or BPA-CB103, is shown in Scheme 2. (EtO)2(O)P NH2Step 1(EtO)2(O)PO Me Scheme 2 The synthesis of tetraethyl ((4-hydroxybutanamido)methylene)bis(phosphonate) in Step 1 of Scheme 2 is shown below. etraethyl (aminomethylene)bis(phosphonate) in anhydrous tetrahydrofuran. Succinic anhydride was added, and the contents were heated at 70oC for 3 h. The reaction mixture was cooled to room temperature and left in freezer (-10oC) for 24 h, which led to the precipitation of the 4- ((bis(diethoxyphosphoryl)methyl)amino)-4-oxobutanoic acid as white solid. The contents were carefully decanted, and the white solid was washed with cold hexane and dried.1H-NMR (400 MHz, CD3OD) ^ 5.06 (t, J = 48 Hz, 1H), 4.28 – 4.11 (m, 8H), 2.59 (s, 4H), 1.39 – 1.24 (m, 12H). An oven dried flask as charged with a solution of ((bis(diethoxyphosphoryl)methyl)amino)-4-oxobutanoic acid in anhydrous tetrahydrofuran. After cooling to 0oC, neat borane dimethyl sulfide was added, and the contents were gradually warmed to room temperature (without removing ice bath) and stirred for 2 h. After cooling to 0oC, the contents were carefully quenched with methanol and stirred at room temperature for 30 min. The reaction mixture was concentrated under reduced pressure and the crude mixture was purified by column chromatography on silica to yield tetraethyl ((4-hydroxybutanamido)- methylene)bis(phosphonate) as colorless oil which slowly solidified to colorless solid upon standing. Rf (Silica) 0.52 (10 % methanol in dichloromethane, KMnO4)1H-NMR (400 MHz, CD3OD) ^ 5.09 (t, J = 22.4 Hz, 1H), 4.23 – 4.05 (m, 8H), 3.57 (t, J = 5.6 Hz, 2H), 2.38 (t, J = 10 Hz, 2H), 1.91 – 1.72 (m, 2H), 1.39 – 1.25 (m, 12H).13C-NMR (125 MHz, CD3OD) ^ 174.56, 64.35 (d, J = 16.25 Hz), 61.44, 44.00 (t, J = 250 Hz), 32.30, 29.02, 16.03 (d, J =10 Hz).31P-NMR (162 MHz, CD3OD) ^ 14.93. Thermo-MS (ESI) m / z (M+Na+) Calcd for C13H29NO8P2Na: 412.13 Found: 412.4. The synthesis of 4-((bis(diethoxyphosphoryl)methyl)amino)-4-oxobutyl (6-(4-(tert- butyl)phenoxy)pyridin-3-yl)carbamate for Step 2 / 3 of Scheme 2 is shown below. ous dichloromethane (0.31 mL, 2.57 mmol in 3 mL). Freshly activated potassium carbonate (0.89 g, 6.43 mmol) was added. After cooling to 0oC, a solution of ((4-hydroxybutanamido)- methylene)bis(phosphonate) in anhydrous dichloromethane (0.5 g, 1.285 mmol in 2 mL) was added dropwise over a period of 5 min and the contents were stirred at 0oC for 3h. The reaction mixture was diluted with anhydrous dichloromethane (20 mL) and the contents were filtered after attaining room temperature. The filtrate was concentrated under reduced pressure to yield 0.541 g of the chloroformate as pale-yellow oil (crude NMR is attached below).1H-NMR (400 MHz, CDCl3) ^ 6.36 (d, J = 9.6 Hz, 1H), 5.34 – 4.87 (m, 1H), 4.36 (t, J = 6.4 Hz, 2H), 4.31 – 4.08 (m, 8H), 2.39 (t, J = 7.2 Hz, 2H), 2.15 – 2.02 (m, 2H), 1.39 – 1.25 (m, 12H).31P-NMR (162 MHz, CDCl3) ^ 14.53. An oven dried round bottom flask was charged with a solution of 6-(4-(tert- butyl)phenoxy)pyridin-3-amine in anhydrous dichloromethane (0.373 g, 1.5 mmol in 3 mL). Freshly activated potassium carbonate (0.89 g, 6.43 mmol) was added. After cooling to 0oC, a solution of chloroformate (0.541 g in 2 mL) was added dropwise over a period of 5 mins and the contents were gradually warmed to room temperature (without removing ice bath) and stirred for 14 h. The reaction mixture was diluted with dichloromethane (20 mL) and filtered. The filtrate was concentrated under reduced pressure and the crude mixture was purified by column chromatography on silica (0 % to 6 % methanol in ethyl acetate) to yield 0.492 mg (58 %) of 4- ((bis(diethoxyphosphoryl)methyl)amino)-4-oxobutyl (6-(4-(tert-butyl)phenoxy)pyridin-3- yl)carbamate as colorless oil. Rf(Silica) 0.37 (10 % methanol in ethyl acetate, UV & KMnO4)1H-NMR (400 MHz, CD3OD) ^ 8.19 (bs, 1H), 7.94 (d, J = 6.8 Hz, 1H), 7.42 (d, J = 8.8 Hz, 2H), 6.97 (d, J = 8.8 Hz, 2H), 6.85 (d, J = 8.8 Hz, 1H), 5.11 (t, J = 23.2 Hz, 1H), 4.28 – 4.11 (m, 10H), 2.44 (t, J = 7.2 Hz, 2H), 2.06 – 1.92 (m, 2H), 1.39 – 1.23 (m, 21H).13C-NMR (125 MHz, CD3OD) ^ 173.86, 160.00, 155.13, 153.25, 147.70, 138.00, 132.73, 131.61, 127.14, 120.44, 112.08, 64.82, 64.39 (d, J = 15 Hz), 44.14 (t, J = 150 Hz), 34.67, 32.22, 31.43, 25.61, 16.25 (d, J = 17.5 Hz).31P-NMR (162 MHz, CD3OD) ^ 14.95. The final step of Scheme 2 for the synthesis of ((4-(((6-(4-(tert-butyl)phenoxy)pyridin-3- yl)carbamoyl)oxy)butanamido)methylene)bis(phosphonic acid) (BPA-CB103) is shown below. 4- ((bis(diethoxyphosphoryl)methyl)amino)-4-oxobutyl (6-(4-(tert-butyl)phenoxy)pyridin-3- yl)carbamate in anhydrous dichloromethane (0.49 g, 0.745 mmol in 3 mL). After cooling to 0oC, neat bromotrimethylsilane (0.6 mL, 4.47 mmol) was added and the contents were gradually warmed to room temperature (without removing ice bath) and stirred overnight. The reaction mixture was concentrated under reduced pressure and the crude was dissolved in anhydrous methanol (5 mL) and concentrated. This procedure was repeated twice. The white foam was dissolved in a mixture of dichloromethane / methanol (10:1, 1.5 mL) and added dropwise to a centrifuge tube containing anhydrous diethyl ether (30 mL) which resulted in the formation of white suspension. The contents were centrifuged, and the supernatant liquid was discarded. The white precipitate was washed with anhydrous diethyl ether (2 x 20 mL) and dried under reduced pressure (35oC for 12 h) to yield ((4-(((6-(4-(tert-butyl)phenoxy)pyridin-3- yl)carbamoyl)oxy)butanamido)methylene)bis(phosphonic acid) as white solid.1H-NMR (400 MHz, CD3OD) ^ 8.12 (bs, 1H), 7.84 (d, J = 8 Hz, 1H), 7.33 (d, J = 8.8 Hz, 2H), 6.95 – 6.81 (m, 3H), 4.54 (t, J = 22.4 Hz, 1H), 2.26 (t, J = 8 Hz, 2H), 188 – 1.73 (m, 2H), 1.20 (s, 9H).13C-NMR (125 MHz, CD3OD) ^ 172.86, 159.60, 155.08, 153.17, 147.80, 138.41, 132,77, 132.09, 127.60, 121.10, 112.71, 65.47, 47.10 (t, J = 137.5 Hz), 35.21, 32.81, 32.37, 25.67.31P-NMR (162 MHz, CD3OD) ^ 12.01. Example 3 BPTB-CB103 (C25H38BrN3O10P2) has a molecular weight = 682.44 g / mol. This conjugate is formed by linking a bone targeting bisphosphonate moiety to an amino pyridine functional group from the CB-103 molecule through a more stabilized aryl carbamate that should cleave and release CB103 more slowly than BPA-CB103 due to the alpha-t-butyl substituent within the bisphosphonate moiety. BPTB-CB103 has the formula

[0092] The synthesis of ((4-(((6-(4-(tert-butyl)phenoxy)pyridin-3-yl)carbamoyl)oxy)-5,5- dimethylhexanamido)methylene)bis(phosphonic acid) (BPTB-CB103) is shown below in Scheme 3.

[0093] Scheme 3

[0094] The synthesis of tetraethyl ((5,5-dimethyl-4-oxohexanamido)methylene)bis(phosphonate) in Step 1 of Scheme 3 is shown below. An o 5,5-dimethyl-4- oxohexanoic acid in anhydrous dichloromethane (2.4 g, 15.18 mmol in 20 mL). Tetraethyl- (aminomethylene)bis(phosphonate) (5.5 g, 18.21 mmol), DIPEA (6.3 mL, 36.43 mmol) and DMAP (2.2 g, 18.21 mmol) were added sequentially. After 10 min EDC (3.78 g, 19.23 mmol) was added portion wise and the contents were stirred at room temperature for 2 d. The reaction mixture was concentrated under reduced pressure and the crude mixture was purified by column chromatography on silica (0 % to 8 % methanol in ethyl acetate) to yield 4.6 g (69 %) of tetraethyl ((5,5-dimethyl-4-oxohexanamido)methylene)bis(phosphonate) as white solid. Rf (silica) 0.34 (10 % methanol in ethyl acetate, KMnO4active)1H-NMR (400 MHz, CD3OD) ^ 5.04 (t, J = 232 Hz, 1H), 4.29 – 4.08 (m, 8H), 2.87 (t, J = 6.4 Hz, 2H), 2.52 (t, J = 6.4 Hz, 2H), 1.39 – 1.23 (m, 12H), 1.13 (s, 9H).13C-NMR (125 MHz, CD3OD) ^ 215.22, 173.74, 64.39 (d, J = 31 Hz), 44.10 (t, J = 149 Hz), 31.98, 29.34, 26.28, 16.05 (d, J = 13.75 Hz).31P-NMR (162 MHz, CD3OD) ^ 14.83. ^ Bioorganic and Medicinal Chemistry, 2012, vol.20, # 13, p.4056 - 4063 The synthesis of tetraethyl ((4-hydroxy-5,5-dimethylhexanamido)methylene) bis(phosphonate) in Step 2 of Scheme 3 is shown below. An oven dried round bottom flask was charged with a solution of tetraethyl ((5,5-dimethyl- 4-oxohexanamido)methylene)bis(phosphonate) in anhydrous tetrahydrofuran (4.5 g, 10.14 mmol 5 in 12 mL). After cooling to 0oC, sodium borohydride was added portion wise (0.767 g, 20.29 mmol) and stirred for an hr. The reaction mixture was quenched with methanol (20 mL) and concentrated under reduced pressure. The crude mixture was purified by column chromatography on silica (0 % to 10 % methanol in ethyl acetate) to yield 4.157 g (92 %) of tetraethyl ((4-hydroxy- 5,5-dimethylhexanamido)methylene)bis(phosphonate) as white solid. Rf (silica) 0.23 (10 % methanol in ethyl acetate, KMnO4 active) 1H-NMR (400 MHz, CD2Cl2) ^7.38 (d, J = 9.6 Hz, 1H), 5.09 – 4.95 (m,1 H), 4.29 – 4.05 (m, 8H), 3.31 (bs, 1H), 3.14 (d, J = 10.4 Hz, 1H), 2.47 (t, J = 6.8 Hz, 2H), 1.96 – 1.81 (m, 1H), 1.59 – 1.41 (m, 1H), 1.35 – 1.23 (m, 12H), 0.89 (s, 9H). 13C-NMR (125 MHz, CD3OD) ^ 174.01, 79.33, 64.20 (m), 44.15 (t, J = 147.5 Hz), 35.57, 34.17, 28.02, 26.20, 16.87 (t, J = 7.5 Hz). 31P-NMR (162 MHz, CD3OD) ^ 14.79. The synthesis of 6-((bis(diethoxyphosphoryl)methyl)amino)-2,2-dimethyl-6-oxohexan-3- yl (6-(4-(tert-butyl)phenoxy)pyridin-3-yl)carbamate in Step 3 / 4 of Scheme 3 is shown below. An oven dried round bottom flask was charged with a solution of diphosgene in anhydrous dichloromethane (0.54 mL, 4.49 mmol in 5 mL). Freshly activated potassium carbonate (1.5 g, 11.2 mmol) was added. After cooling to 0oC, a solution of tetraethyl ((4-hydroxy-5,5- dimethylhexanamido)methylene)bis(phosphonate) in anhydrous dichloromethane (1 g, 2.24 mmol in 2 mL) was added dropwise over a period of 5 min and the contents were stirred at 0oC for 3h. The reaction mixture was diluted with anhydrous dichloromethane (25 mL) and the contents were filtered after attaining room temperature. The filtrate was concentrated under reduced pressure to yield 1.051 g of the chloroformate as pale-yellow oil. An oven dried round bottom flask was charged with a solution of 6-(4-(tert- butyl)phenoxy)pyridin-3-amine in anhydrous dichloromethane (0.654 g, 2.68 mmol in 5 mL). Freshly activated potassium carbonate (1.5 g, 11.2 mmol) was added. After cooling to 0oC, a solution of chloroformate (1.051 g in 2 mL) was added dropwise over a period of 5 min and the contents were gradually warmed to room temperature (without removing ice bath) and stirred for 14 h. The reaction mixture was diluted with dichloromethane (30 mL) and filtered. The filtrate was concentrated under reduced pressure and the crude mixture was purified by column chromatography on silica (0 % to 4 % methanol in ethyl acetate) to yield 0.89 g (56 %) of 6- ((bis(diethoxyphosphoryl)methyl)amino)-2,2-dimethyl-6-oxohexan-3-yl (6-(4-(tert- butyl)phenoxy)-pyridin-3-yl)carbamate as pale yellow foam. Rf (silica) 0.27 (4 % methanol in ethyl acetate, UV & KMnO4 active)1H-NMR (400 MHz, CD2Cl2) ^ 8.186 (bs, 1H), 7.40 (dd, J1 = 2 Hz, J2 = 6.4 Hz, 1H), 7.01 (d, J = 8.8 Hz, 1H), 5.13 – 4.97 (m, 1H), 4.75 (bs, 1H), 4.29 – 4.01 (m, 8H), 2.49 – 2.31 (m, 2H), 2.11 – 1.88 (m, 2H), 1.45 – 1.21 (m, 12H), 0.98 (s, 9H).13C-NMR (125 MHz, CD2Cl2) ^ 172.75, 160.16, 155.41, 153.18, 147.88, 138.62, 132.30, 131.44, 127.11, 120.95, 111.93, 81.78, 64.18, 44.20 (t, J = 21.25 Hz), 35.58, 35.01, 33.69, 31.95, 26.48, 16.93.31P-NMR (162 MHz, CD2Cl2) ^ 14.81. The synthesis of ((4-(((6-(4-(tert-butyl)phenoxy)pyridin-3-yl)carbamoyl)oxy)-5,5- dimethylhexanamido)methylene)bis(phosphonic acid) (BPTB-CB103) in Step 5 of Scheme 3 is shown below. An oven dried round bottom flask was charged with a solution of 6- ((bis(diethoxyphosphoryl)methyl)amino)-2,2-dimethyl-6-oxohexan-3-yl (6-(4-(tert-butyl)- phenoxy)pyridin-3-yl)carbamate (1 g, 1.4 mmol in 5 mL). After cooling to 0oC, neat bromotrimethylsilane (1.1 mL, 8.4 mmol) was added and the contents were gradually warmed to room temperature (without removing ice bath) and stirred overnight. The reaction mixture was concentrated under reduced pressure and the crude was dissolved in anhydrous methanol (5 mL) and concentrated. This procedure was repeated twice. The white foam was dissolved in a mixture of dichloromethane / methanol (10:1, 6 mL) and added dropwise to a centrifuge tube containing anhydrous diethyl ether (50 mL) which resulted in the formation of white suspension. The contents were centrifuged, and the supernatant liquid was discarded. The white precipitate was washed with anhydrous diethyl ether (2 x 20 mL) and dried under reduced pressure (35oC for 12 h) to yield 742 mg of ((4-(((6-(4-(tert-butyl)phenoxy)pyridin-3-yl)carbamoyl)oxy)-5,5-dimethylhexanamido)- methylene)bis(phosphonic acid) as pale brown solid.1H-NMR (500 MHz, CD2Cl2) ^ 8.78 (bs, 1H), 8.30 (d, J = 10 Hz, 1H), 7.57 (d, J = 5Hz, 2H), 7.23 (d, J = 5 Hz, 2H), 7.13 (d, J = 5 Hz, 1H), 4.82 (t, J = 20 Hz), 4.69 (d, J = 10 Hz, 1H), 2.45 – 2.31 (m, 2H), 2.15 – 1.95 (m, 2H), 1.89 – 1.72 (m, 1H), 1.34 (s, 9H), 0.96 (s, 9H).13C-NMR (125 MHz, CD3OD) ^ 174.10, 156.41. 156.32, 151.15, 150.85, 139.11, 134.44, 128.83, 128.30, 120.48, 113.51, 82.98, 46.70 (t, J = 16.25 Hz), 35.24, 34.93, 33.13, 31.12, 26.32, 25.65.31P-NMR (162 MHz, CD3OD) ^ 11.98 Example 4 BPTF-CB103 (C22H29BrF3N3O10P2) has molecular weight = 682.44 g / mol. This conjugate is formed by linking a bone targeting moiety link to CB-103 through a more labile aryl carbamate that should cleave and release CB103 faster due to the alpha-CF3 substituent within the bisphosphonate moiety. BPTF-CB103 has the formula . The synthesis of ((4-(((6-(4-(tert-butyl)phenoxy)pyridin-3-yl)carbamoyl)oxy)-5,5,5- trifluoropentanamido)methylene)bis(phosphonic acid) (BPTF-CB103) in Scheme 4 is shown below.

[0095] O O OTBS Ste OTBS Step 2 EtO p 1 HO )2H Me The synthesis of 4-((tert-butyldimethylsilyl)oxy)-5,5,5-trifluoropentanoic acid in Step 1 of Scheme 4 is shown below. A round bottom flask was charged with a solution of ethyl 4-((tert-butyldimethylsilyl)- oxy)-5,5,5-trifluoropentanoate*in tetrahydrofuran (4 g, 12.72 mmol in 11 mL). Methanol (11 mL) and an aqueous solution of lithium hydroxide mono hydrate (1.6 g, 31.80 mmol in 11 mL) were added and the turbid solution was stirred vigorously for 7 h. After concentration under reduced pressure, the pH of the crude mixture was carefully adjusted to 4 using 1N HCl solution. The aqueous layer was extracted with ethyl acetate (5 x 50 mL) and the combined organic layer was washed with brine (1x 50 mL), dried over anhydrous sodium sulphate, filtered, and concentrated under reduced pressure to yield 3.86 g (99 %) of 4-((tert-butyldimethylsilyl)oxy)-5,5,5-trifluoro- pentanoic acid as colorless oil. The crude acid was taken to the next step without purification.1H-NMR (400 MHz, CDCl3) ^ 4.15 – 401 (m, 1H), 2.63 (t, J = 7 Hz, 1H), 2.53 (t J = 7 Hz, 1H), 2.15 – 1.82 (m, 2H), 0.9 (s, 9H), 0.1 (s, 3H), 0.96 (s, 3H). The synthesis of tetraethyl ((4-((tert-butyldimethylsilyl)oxy)-5,5,5- trifluoropentanamido)methylene)bis(phosphonate) in Step 2 of Scheme 4 is shown below. An on of 4-((tert- butyldimethylsilyl)oxy)-5,5,5-trifluoropentanoic acid in anhydrous dichloromethane (3.8 g, 13.26 mmol in 26 mL). Tetraethyl-(aminomethylene)bis(phosphonate) (5.2 g, 17.24 mmol), DIPEA (5.8 mL, 33.15 mmol) and DMAP (1.62 g, 13.26 mmol) were added sequentially. After 10 min EDC (3.3 g, 17.24 mmol) was added portion wise and the contents were stirred at room temperature for 2 d. The reaction mixture was concentrated under reduced pressure and the crude mixture was purified by column chromatography on silica (0 % to 6 % methanol in ethyl acetate) to yield 4.776 g (63 %) of tetraethyl ((4-((tert-butyldimethylsilyl)oxy)-5,5,5-trifluoropentanamido)methylene)- bis(phosphonate) as pale yellow oil. Rf (silica) 0.54 (10 % methanol in ethyl acetate, KMnO4 active)1H-NMR (400 MHz, CD2Cl2) ^ 6.91 (d, J = Hz, 1H), 5.11 – 4.91 (m, 1H), 4.29 – 4.06 (m, 10 H), 2.02 (t, J =.2H), 2.12 – 1.95 (m, 1H), 1.95 – 1.81 (m, 1H), 1.36 – 1.25 (m, 12H), 0.91 (s, 9H), 0.12 (s, 3H), 0.11 (s, 3H).13C-NMR (125 MHz, CD2Cl2) ^ 172.50, 125.24 (q, J = 282 Hz), 70.81 (t, J = 30 Hz), 63.88 (d, J = 29 Hz).44.04 (t, J = 146.25 Hz), 30.06, 27.64, 25.98, 18.53, 16.73 (d, J = 12.5 Hz), -4.50, -4.96.31P-NMR (162 MHz, CD2Cl2) ^ 14.4819F-NMR (400 MHz, CD2Cl2) ^ -78.44 The synthesis of tetraethyl ((5,5,5-trifluoro-4-hydroxypentanamido)methylene) bis(phosphonate) in Step 3 of Scheme 4 is shown below. l ((4-((tert- butyldimethylsilyl)oxy)-5,5,5-trifluoropentanamido)methylene)-bis(phosphonate in anhydrous tetrahydrofuran (3.75 g, 6.56 mmol in 7 mL). A solution of tetrabutylammonium chloride in tetrahydrofuran was added at 0oC, and the contents were gradually warmed to room temperature (without removing ice bath) and stirred for 3 h. The reaction mixture was concentrated under reduced pressure and the crude mixture was purified by column chromatography on silica (0 % to 10 % methanol in ethyl acetate) to yield 2.48 g (83%) of tetraethyl ((5,5,5-trifluoro-4- hydroxypentanamido)methylene)bis(phosphonate) as white solid. Rf (silica) 0.15 (10 % methanol in ethyl acetate, KMnO4active)1H-NMR (400 MHz, CD2Cl2) ^ 7.78 (d, J = 7.2 Hz, 1H), 5.19 – 4.98 (m, 1H), 4.29 – 4.02 (m, 8 H), 3.99- 3.81 (m, 1H), 2.73 – 2.61 (m, 1H), 2.61 – 2.41 (m, 1H), 2.14 – 2.01 (m, 1H), 1.94 – 1.78 (m, 1H), 1.41- 1.21 (m, 12H).13C-NMR (125 MHz, CD2Cl2) ^ 173.50, 126.31(q, J = 279 Hz), 69.60 (q, J = 30 Hz), 65.51(dq, J1 = 5 Hz, J2 = 20 Hz), 44.11 (t, J = 150 Hz), 31.74, 26.74, 16.78 (d, J = 5 Hz). 31P-NMR (162 MHz, CD2Cl2) ^ 14.49. 19F-NMR (400 MHz, CD2Cl2) ^ -79.96. The synthesis of 5-((bis(diethoxyphosphoryl)methyl)amino)-1,1,1-trifluoro-5-oxopentan- 2-yl (6-(4-(tert-butyl)phenoxy)pyridin-3-yl)carbamate in Step 4 / 5 of Scheme 4 is shown below. An oven dried round bottom flask was charged with a solution of diphosgene in anhydrous dichloromethane (0.53 mL, 4.37 mmol in 5 mL). Freshly activated potassium carbonate (1.5 g, 11.2 mmol) was added. After cooling to 0oC, a solution of tetraethyl ((4-hydroxy-5,5- dimethylhexanamido)methylene)bis(phosphonate) in anhydrous dichloromethane (1 g, 2.18 mmol in 2 mL) was added dropwise over a period of 5 min and the contents were gradually warmed to room temperature and stirred for 24 h. The reaction mixture was diluted with anhydrous dichloromethane (25 mL) and the contents were filtered after attaining room temperature. The filtrate was concentrated under reduced pressure to yield 1.039 g of the chloroformate as pale- yellow oil. 1H-NMR (400 MHz, CD2Cl2) ^ 7.23 (bs, 1H), 5.59 – 5.45 (m, 1H), 5.11 – 4.89 (m, 1H), 4.31- 4.08 (m.8H), 2.61 – 2.41 (m, 2H), 2.39 – 2.22 (m, 1H), 2.21 – 2.03 (m, 1H), 1.47 – 1.21 (m, 12H). An oven dried round bottom flask was charged with a solution of 6-(4-(tert- butyl)phenoxy)pyridin-3-amine in anhydrous dichloromethane (0.581 g, 2.34 mmol in 7 mL). Freshly activated potassium carbonate (1.5 g, 10.9 mmol) was added. After cooling to 0oC, a solution of chloroformate (1.039 g in 2 mL) was added dropwise over a period of 5 min and the contents were gradually warmed to room temperature (without removing ice bath) and stirred for 14 h. The reaction mixture was diluted with dichloromethane (30 mL) and filtered. The filtrate was concentrated under reduced pressure and the crude mixture was purified by column chromatography on silica (0 % to 5 % methanol in ethyl acetate) to yield 0.851 g (52 %) of 6- ((bis(diethoxyphosphoryl)methyl)amino)-2,2-dimethyl-6-oxohexan-3-yl (6-(4-(tert- butyl)phenoxy)-pyridin-3-yl)carbamate as white powder. Rf (silica) 0.31 (4 % methanol in ethyl acetate, UV & KMnO4active)1H-NMR (400 MHz, CDCl3) ^ 9.08 (bs, 1H), 8.25 (bs, 1H), 8.08 (d, J = 9.6 Hz, 1H), 7.37 (d, J = 8.4 Hz, 2H), 7.16 (d, J = 8.4 Hz, 2H), 6.84 (d, J = 8.4 Hz, 2H), 6.18 (d, J = 8 Hz, 1H), 5.49 – 5.399m, 1H), 5.13 – 4.96 (m, 1H) 4.29 – 4.05 (m, 8H), 2.55 – 2.31 (m, 3H), 2.12 – 2.03 (m, 1H), 1.39 – 1.23 (m, 21H).13C-NMR (125 MHz, CD2Cl2) ^ 171.93, 160.52, 153.10, 152.90, 147.99, 138.90, 131.77, 131.53, 127.08, 121.02, 11.09, 70.02 (dd, J1= 5 Hz, J2= 20 Hz), 44.23 (t, J = 141 Hz), 35.01, 31.93, 31.13, 24.34, 16.85 (d, J = 5Hz).31P-NMR (400 MHz, CD2Cl2) ^ 14.7719F-NMR (400 MHz, CD2Cl2) ^ -76.26 The synthesis of ((4-(((6-(4-(tert-butyl)phenoxy)pyridin-3-yl)carbamoyl)oxy)-5,5,5- trifluoropentanamido)methylene)bis(phosphonic acid) (BPTF-CB103) in Step 6 of Scheme 4 is shown below. An oven dried round bottom flask was charged with a solution of 6- ((bis(diethoxyphosphoryl)methyl)amino)-2,2-dimethyl-6-oxohexan-3-yl (6-(4-(tert- butyl)phenoxy)-pyridin-3-yl)carbamate (0.773 g, 1.06 mmol in 3 mL). After cooling to 0oC, neat bromotrimethylsilane (0.84 mL, 6.39 mmol) was added and the contents were gradually warmed to room temperature (without removing ice bath) and stirred overnight. The reaction mixture was concentrated under reduced pressure and the crude was dissolved in anhydrous methanol (5 mL) and concentrated. This procedure was repeated twice. The white foam was dissolved in a mixture of dichloromethane (2.5 mL) and added dropwise to a centrifuge tube containing anhydrous diethyl ether (30 mL) which resulted in the formation of white suspension. The contents were centrifuged, and the supernatant liquid was discarded. The white precipitate was washed with anhydrous diethyl ether (2 x 20 mL) and dried under reduced pressure (35oC for 12 h) to yield 687 mg of ((4-(((6-(4- (tert-butyl)phenoxy)pyridin-3-yl)carbamoyl)oxy)-5,5-dimethylhexanamido)- methylene)bis(phosphonic acid) as pale brown solid.1H-NMR (500 MHz, CD3OD) ^ 8.58 (bs, 1H), 8.21 (d, J = 9.2 Hz, 1H), 7.54 (d, J = 8.8 Hz, 1H), 7.16 (d, J = 8.8 Hz, 1H), 7.07 ((d, J = 8.8 Hz, 1H), 5.55 – 5.41 (m, 1H), 4.81 (t, J = 22 Hz, 1H), 2.59 – 2.41 (m, 2H), 2.32 – 2.21 (m, 1H), 2.21 – 2.03 (m, 1H), 1.38 (s, 9H).13C-NMR (125 MHz, CD3OD) ^ 172.89, 157.85, 153.13, 151.41, 150.44, 137.50, 133.29, 131.56, 127.98, 125.88, 123.59, 120.44, 113.11, 70.99 (q, J = 37.5 Hz), 46.72 (t, J = 20 Hz), 34.84, 30.92 (d, J = 46 Hz), 24.31.31P-NMR (400 MHz, CD3OD) ^ 13.13.19F-NMR (400 MHz, CD2Cl2) ^ -78.72. Note: Traces of heptane is trapped in the final sample despite drying the sample at 40oC overnight. Example 5 The bisphosphonates BPA, BPTB, BPTF that are released after cleavage of each linkage compound (BPA (C5H13NO8P2, MW = 277.11 g / mol), BPTB (C9H21NO8P2, MW = 333.21 g / mol, and BPTF (C6H12F3NO8P2, MW = 345.1 g / mol), as controls, in particular BPTB and BPTF that are novel chemical entities for this purpose. BPA has the formula . BPTB has the formula . BPTF has the formula . The synthesis of ((5,5,5-trifluoro-4-hydroxypentanamido)methylene)bis(phosphonic acid) (BPTF) as a control compound is shown below. An oven dried round bottom flask was charged with a solution of tetraethyl ((5,5,5- trifluoro-4-hydroxypentanamido)methylene)bis(phosphonate) (0.345 g, 0.754 mmol in 2 mL). After cooling to 0oC, neat bromotrimethylsilane (0.6mL, 4.52 mmol) was added and the contents were gradually warmed to room temperature (without removing ice bath) and stirred overnight. The reaction mixture was concentrated under reduced pressure and the crude was dissolved in anhydrous methanol (5 mL) and concentrated. This procedure was repeated twice. The white foam was dissolved in water (10 mL) and washed with diethyl ether (2 x 10 mL). The aqueous layer was concentrated under reduced pressure. The white foam was suspended in methanol / acetonitrile (10 mL (1:1)) and concentrated to remove last traces of water to yield ((5,5,5-trifluoro-4- hydroxypentanamido)methylene)bis(phosphonic acid) as white foam.1H-NMR (500 MHz, CD3OD) ^ 8.58 (bs, 1H), 8.21 (d, J = 9.2 Hz, 1H), 7.54 (d, J = 8.8 Hz, 1H), 7.16 (d, J = 8.8 Hz, 1H), 7.07 ((d, J = 8.8 Hz, 1H), 5.55 – 5.41 (m, 1H), 4.81 (t, J = 22 Hz, 1H), 2.59 – 2.41 (m, 2H), 2.32 – 2.21 (m, 1H), 2.21 – 2.03 (m, 1H), 1.38 (s, 9H).13C-NMR (125 MHz, CD3OD) ^ 173.90, 125.36 (q, J = 270 Hz), 69.24 (dd, J1= 31 Hz, J2= 59 Hz, 53.23, 45.53 (t, J = 146 Hz), 31.24, 26.00.31P-NMR (400 MHz, CD3OD) ^ 13.13.19F-NMR (400 MHz, CD2Cl2) ^ -81.47. Example 6 Testing Results 1. In vitro work in myeloma cancer cells shows that treatment with CB-103 decreases their proliferation and induces apoptosis of these cells similarly to the action of the Notch inhibitor GSI. (Figure 1 and Figure 3) 2. HES and HEY genes encode for bHLH transcription factors identified as Notch targets. Ex vivo work in organ cultures established with bones from Notch reporter mice shows that CB- 103 decreases Notch signaling in bone cells. (Figure 2 and Figure 4) 3. Ex vivo work in organ cultures established with bones from naïve mice shows that BPA- CB103, BPTB-CB103, and BPTF-CB103 downregulate the expression of Notch target genes similarly to a bone-targeted Notch inhibitor based on GSI-XII (CAS No.161710-10-7). (Figure 5) 4. Ex vivo work in organ cultures established with bones from naive mice shows that BPA- CB103, BPTB-CB103, and BPTF-CB103 downregulate the expression of Rankl, a cytokine essential for the formation of osteoclast and bone destruction. (Figure 5)

[0096] 5. Ex vivo work in organ cultures established with bones from naive mice shows that BPA, BPTB, and BPTF do not affect the expression of Notch target genes or Rankl. (Figure 5)

[0097] 6. The inventors have extensively characterized the in vivo effects (PK, PD, bone disease, tumor burden, toxicity, etc.) of a previously generated bone-targeted GSI inhibitor (US20200368259A1) in immunodeficient and immunocompetent preclinical models of cancer in bone.

[0098] Example 7

[0099] Figure 7 shows data regarding the effects of bone-targeted CB-103 compounds on Notch signaling in MM cells.

[0100] Brief summary

[0101] CB-103 is a compound that acts as a pan-Notch inhibitor. Its mechanism of action involves targeting the Notch transcriptional activation complex by specifically inhibiting the Mastermind Like protein (MAML). This inhibition ultimately leads to cell death. In cancer, the Notch pathway can promote tumor growth and development, making it an attractive target for therapeutic intervention. Notch inhibitors aim to block the signaling cascade and potentially slow down or inhibit cancer cell growth. We have CB-103 (active compound) attached with a pH sensitive linker to different Bisphosphonates (BT). These BTs are novel because they are attached to different chemical moi eties which are cleaved and release CB-103 at acidic sites and hence increase the CB-103 on site.

[0102] Previous research studies have shown that increased Notch signaling activity in myeloma cells promotes cell growth and survival by regulating the expression of genes involved in these processes. Targeting the Notch pathway has been investigated as a potential therapeutic strategy in multiple myeloma (MM). The progression of multiple myeloma (MM) is facilitated by increased osteoclastogenesis via Rankl. Osteoclasts create lytic sites with a low pH, which can be targeted by delivering CB-103, aNotch inhibitor, using various drivers that can withstand the low pH. This approach is being tested on both human and murine MM cell lines to treat MM.

[0103] Methods To achieve this, Human MM cells (JJN3) and murine MM cells (5TGM1) were seeded (50K per well) in 24 well plates and treat with all CB-103 (15uM) and other conjugates for 48h. We also included GSI in this study. In every 24h we add CB-103 and conjugates over the top. After 48h, the cells were extracted and gene expression (qPCR) for Notch targeted genes were performed. The quantified RNA used to prepare cDNA was 1500ng.

[0104] Conclusion

[0105] Gene expression data revealed that in JJN3 cells, GSI was the compound which is consistently decreased all Notch targeted genes significantly. CB-103 and BPTF-CB103 were other potent compounds which were able to regress most of the Notch targeted genes.

[0106] Example 8

[0107] Figure 8 shows data regarding the lack of effects of bone-targeting moieties on Notch signaling in MM cells lines.

[0108] Brief summary

[0109] To rule out the effect of Notch targeted genes regression primarily and only due to the active compound (CB-103) we were interested in knowing if the drivers alone can have any effects on Notch targeted genes regression.

[0110] Methods

[0111] To achieve this, Human MM cells (JJN3) and murine MM cells (5TGM1) were seeded (50K per well) in 24 well plates and treat with all 3 drivers and BT for 48h. In every 24h we again added drivers and BT compound over the top. After 48h, the cells were extracted and gene expression (qPCR) for Notch targeted genes were performed. The quantified RNA used to prepare cDNA was 1500ng.

[0112] Conclusion

[0113] Gene expression data revealed that drivers alone and BT has no effects on Notch targeted genes.

[0114] Example 9

[0115] Figure 9 shows data demonstrating that bone-targeted CB-103 conjugates, but not bone- targeting moieties, decrease proliferation and induce cell death in myeloma cell lines.

[0116] Brief summary Previous data showed that CB-103 and conjugates able to inhibit Notch targeted genes compared to the control. It was interesting to know if these compounds and drivers are having anti- MM effects or not. To achieve this, proliferation and cell death in the JJN3 and 5TGM1 were evaluated.

[0117] Methods

[0118] Proliferation and cell death of JJN3 and 5TGM1 were evaluated by counting the cells after the treatment (15uM). The cells were treated with CB-103 and conjugates for 48h and were counted using trypan blue staining method for proliferation cell death (blue stained cells).

[0119] Conclusion

[0120] JJN3 and 5TGM1 both shows decline in cellular proliferation with an increase in cell death. In this experiment, BPTF-CB 103 shows the maximum cell death compared to other compounds. No changes in proliferation and cell death were detected while treated with drivers only.

[0121] Example 10

[0122] An in vivo study was conducted to test the effects of one of the compounds, BPA-CB103. At the dose used (2.5mg / kg, 3 times / week), the conjugate decreases Notch in bone as observed by a decrease in Notch target gene expression (Heyl mRNA). Further, this dose mitigates the bone loss induced by myeloma cancer cells, as observed by the cancellous bone mass of the tibia as compared to the naive sample. However, at this dose, the growth of the tumors is not affected as demonstrated by the serum paraprotein, indicator of tumor burden.

Claims

CLAIMSWe claim:

1. A compound comprising a bone-targeting group, a notch inhibitor moiety, and a linker L therebetween.

2. The compound of claim 1, wherein the notch inhibitor moiety has the formulawherein R is selected from the group consisting of tert-butyl, tert-pentyl, cyclohexyl, (3r,5r,7r)- adamantan-l-yl, and wherein W is selected from the group consisting of N, CH, or CF.

3. The compound of any one of claims 1-2, wherein the bone targeting group comprises a bis-phosphonate group.

4. The compound of any one of claims 1-3, wherein L comprises a saturated or unsaturated alkyl or a polyethylene glycol optionally substituted with one or more substituents selected from alkyl, haloalkyl, aryl, heteroaryl, heterocyclic, cycloalkyl, and any combination thereof.

5. A compound of claim 1, wherein the compound has Formula (I)or a pharmaceutically acceptable salt thereof, whereinRi is H, alkyl, or aryl;R2 is tert-butyl, tert-pentyl, cyclohexyl, or (3r,5r,7r)-adamantan-l-yl; andL is a saturated or unsaturated alkyl or a polyethylene glycol optionally substituted with one or more substituents selected from alkyl, haloalkyl, aryl, heteroaryl, heterocyclic, cycloalkyl, and any combination thereof.

6. The compound of claim 5, wherein R2 is tert-butyl.

7. The compound of claim 5, wherein R1is H.

8. The compound of any one of claims 5-7, wherein L is an alkyl of 1 to 3 carbons optionally substituted with an alkyl or haloalkyl.

9. The compound of claim 1, wherein the compound has Formula (II), einR3is selected from the group consisting of H, CF3, t-Bu, cyclopropyl, alkyl, aryl, heteroaryl, heterocyclic, cycloalkyl; n is any number between 0 and 10; X is any of O, N, S, or CH2; Y is any of O, N, S, CH2; and Z is any of O, NH, S.

10. The compound of claim 9, wherein the compound has Formula (III), N O O I).

11. The compound of claim 9, wherein the compound has Formula (IV),V).

12. The compound of claim 9, wherein the compound has Formula (V), V).

13. The compound of claim 1, wherein the compound has Formula (VI), ), whereinlkyl, or aryl; R3 is selected from the group consisting of H, CF3, t-Bu, cyclopropyl, alkyl, aryl, heteroaryl, heterocyclic, cycloalkyl; n is any integral number between 0 and 10; A is selected from the group consisting of alkyl, alkenyl, alkynyl, phenyl, O, N, S; X is selected from the group consisting of O, N, S, or CH2; and Y is selected from the group consisting of O, N, S, CH2.

14. The compound of claim 1, wherein the compound has Formula (VII), I), whereinRi is selected from the group consisting of H, alkyl, or aryl;R3 is selected from the group consisting of H, CF3, t-Bu, cyclopropyl, alkyl, aryl, heteroaryl, heterocyclic, cycloalkyl; m is any integral number between 0 and 10;X is selected from the group consisting of O, N, S, or CH2; andY is selected from the group consisting of O, N, S, CH2.

15. The compound of claim 1, wherein the compound has Formula (VIII),whereinRi is selected from the group consisting of H, alkyl, or aryl;B is selected from the group consisting of CH or N;X is selected from the group consisting of O, N, S, or CH2; andY is selected from the group consisting of O, N, S, CH2.

16. The compound of claim 1, wherein the compound has Formula (IX),whereinRi is selected from the group consisting of H, alkyl, or aryl;C is selected from the group consisting of CH2, NH, NMe, O, or S;D is any integral number between 0 and 4;X is selected from the group consisting of O, N, S, or CH2; andY is selected from the group consisting of O, N, S, CH2.

17. A pharmaceutical composition comprising the compound according to any one of claims 1-16 or a pharmaceutically acceptable salt thereof and a pharmaceutically acceptable excipient, carrier, or diluent.

18. A method for the treatment of bone loss comprising administering an effective amount of the compound of claim 1 or a pharmaceutically acceptable salt thereof to a subject in need thereof.

19. A method for reducing or inhibiting bone tumor growth comprising administering an effective amount of the compound of claim 1 or a pharmaceutically acceptable salt thereof to a subject in need thereof.

20. The method of claim 18 or 19, wherein the subject in need has multiple myeloma.

21. The method of claim 18 or 19, wherein the subject in need has leukemia.

22. The method of claim 18 or 19, wherein the subject in need has bone tumor growth associated with sarcoma.

23. The method of claim 18 or 19, wherein the subject in need has bone tumor growth associated with cancer metastasis.

24. A method of inhibiting the growth or proliferation of bone tumor cells comprising contacting the bone tumor cells with the compound according to claim 1 or a pharmaceutically acceptable salt thereof.

25. A method of inducing apoptosis of bone tumor cells comprising contacting the bone tumor cells with the compound according to claim 1 or a pharmaceutically acceptable salt thereof.

26. A method of inhibiting a CSL-NICD gene transcription complex in bone tumor cells comprising contacting the bone tumor cells with the compound according to claim 1 or a pharmaceutically acceptable salt thereof.

27. A method of downregulating the expression of Rankl in bone tumor cells comprising contacting the bone tumor cells with the compound according to claim 1 or a pharmaceutically acceptable salt thereof.

28. A method of downregulating the expression of HES genes in bone tumor cells comprising contacting the bone tumor cells with the compound according to claim 1 or a pharmaceutically acceptable salt thereof.

29. A method of downregulating the expression of HEY genes in bone tumor cells comprising contacting the bone tumor cells with the compound according to claim 1 or a pharmaceutically acceptable salt thereof.

30. The method of any one of claims 24-29, wherein the bone tumor cells are multiple myeloma cells.

31. The method of any one of claims 24-30, wherein the contacting step is performed in vitro or ex vivo.

32. The method of any one of claims 24-30, wherein the contacting step is performed in vivo.

33. The method of any one of claims 18-32, wherein the compound is the compound according to any one of claims 2-16.

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