WO2007143630A2 - Treatment of neurofibromatosis with hsp90 inhibitors - Google Patents

Abstract

The invention includes methods of treating NF2-deficient or NF1-deficient cells with the HSP90 inhibiting compound and assessing degradation and activity of one or more client proteins of HSP90 and/or upregulation of HSP70 which are important for the proliferation and survival of NF2-deficient or NF1-deficient tumor cells. The present invention is directed to methods of inhibiting the growth of NF2-deficient or NF1-deficient tumors. The methods comprise contacting NF2-deficient or NF1-deficient tumor cells with a compound that inhibits the function of heat shock protein 90 (HSP90). The present invention is also directed to methods of screening a test compound for treatment of NF2 or NF1 and related conditions.

Description

TREATMENT OF NEUROFIBROMATOSIS WITH HSP90 INHIBITORS

CROSS REFERENCE TO RELATED APPLICATIONS

[0001] This application claims priority to U.S. Serial No. 60/810,166, filed on June 2, 2006, which is incorporated in its entirety by reference. FIELD OF INVENTION

[0002] The present invention relates to the use of heat shock protein 90 (HSP90) inhibitors for treatment of neurofibromatosis type 2 (NF2) and neurofibromatosis type 1 (NFl).

BACKGROUND

[0003] Neurofibromatosis includes two diseases, neurofibromatosis type 1 (NFl) and neurofibromatosis type 2 (NF2). Both NFl and NF2 are inherited disorders and both encompass mutations which predispose individuals to multiple tumors of the central or peripheral nervous system, and occasionally to other malignancies. Major tumor types associated with NFl and NF2 involve glial cells (e.g. Schwann cells and astrocytes).

Although there is the similarity of the involvement of Schwann cells in NFl and NF2 tumors,

NFl and NF2 have a spectrum of tumors which involve different types of cells. In addition,

NFl and NF2 are caused by different gene mutations.

Neurofibromatosis type 2

[0004] Neurofibromatosis type 2 (NF2) is a rare form of neurofibromatosis, which is a dominantly inherited tumor suppressor disorder, that affects approximately 1 in 25,000 individuals and is characterized by multiple tumors on the cranial and spinal nerves. NF2 is a different disease from NFl , neurofibromatosis type 1. Although both NFl and NF2 are tumor predisposition syndromes in the nervous system, the tumor suppressor genes are different and signaling pathways are likely to be different.

[0005] Individuals with NF2 are at a high risk for developing brain tumors, in particular tumors on both the seventh and eighth cranial nerves. Bilateral vestibular schwannomas, a type of tumor which occurs on these nerves, occurs in about 95% of affected individuals.

Consequently, hearing loss, ringing in the ears, and problems with balance are symptoms frequently associated with NF2.

[0006] Schwannomas are tumors consisting of nerve sheath cells or Schwann cells (SCs).

Schwann cells support and protect nerve cells and provide nerves with the insulation they need to conduct information. Bilateral vestibular schwannomas, also known as acoustic neuromas, as well as spinal schwannomas and schwannomas of the peripheral nerves are common manifestations of NF2. The symptoms of a schwannoma will depend on its location.

[0007] In addition to schwannomas, individuals with NF2 may develop other types of tumors emanating from the nerves, meningeal envelopes, brain and spinal cord. The most common tumor of this type is meningioma; other less common tumors include ependymomas and astrocytomas. Moreover, NF2 patients may have an increased risk for developing mesotheliomas.

Molecular Role of Merlin

[0008] NF2 is an autosomal dominant genetic trait, meaning it affects both genders equally and each child of an affected parent has a fifty percent chance of inheriting the gene. NF2 results from a mutation or a deletion of the NF2 gene and is transmitted on chromosome 22

(Sainz et al, 1994, Hum. MoI. Genet. 3: 885-891 ; Ruttledge et al, 1994, Nat. Genet. 6: 180-

184; Rubio et al., 1994, Cancer Res. 54: 45-47; Huynh et al., 1997, J. Neuropathol. Exp.

Neurol. 56: 382-390).

[0009] The NF2 gene is a tumor suppressor gene that encodes a 595-amino acid protein, termed Merlin. Merlin belongs to the ezrin, radixin, and moesin (ERM) family of proteins

(Trofatter et al, 1993, Cell. 75: 826).

[0010] Over-expression of Merlin can block both cell proliferation and oncogene-induced transformation (Lutchman and Rouleau, 1995, Cancer Res. 55(1 1): 2270-2274; Tikoo et al,

1994, J. Biol. Chem. 269(38): 23387-23390). Indeed, Merlin can negatively regulate cyclin

Dl levels (Xiao et al, 2002, J. Biol. Chem. 277: 883-886) and loss of Merlin results in overexpression of cyclin Dl (Lallemand et al., 2003, Genes Dev. 17: 1090-1 100). However, given its predominant localization to the membrane and cytoskeleton interface, Merlin is not likely to directly control the cell cycle machinery.

[0011] The mechanism by which loss of NF2 may contribute to tumor development is not clear. Many studies have focused on this issue using both genetic and biochemical approaches. Several lines of evidence suggest that Merlin can regulate receptor tyrosine kinase activity, trafficking, and degradation. Merlin has been shown to interact directly with the focal adhesion component paxillin in a complex that contains integrin-βl and ErbB2

(Fernandez-Valle et al, 2002, Nat. Genet. 31 (4): 354-362), HGF receptor substrate (HRS)

(Scoles et al, 2002, Hum. MoI. Genet. 1 1 (25): 3179-3189; Gutmann et al, 2001 , Hum. MoI.

Genet. 10(8): 825-834; Soles et al, 2000, Hum. MoI. Genet. 9(1 1): 1567-1574), and platelet derived growth factor receptor (PDGFR) indirectly through interaction with a PDZ- containing adaptor protein EBP50/NHE-RF (Maudsley et al, 2000, MoI. Cell Biol. 20(22): 8352-8363; Murthy et al, 1998, J. Biol. Chem. 273(3): 1273-1276). Neuregulin growth factors (EGF family of growth factors), VEGF, and HGF are important mitogens for Schwann cells (SCs) (Krasnoselsky et al, 1994, J. Neurosci. 14:7284-7290; DeClue et al, 2000, J. Clin. Invest. 105(9):1233-1241 ; Caye-Thomasen et al, 2005, Otol. Neurotol. 26(l):98-101). Neuregulin/ErbB pathways are constitutively activated in human NF2 vestibular schwannomas and inhibitors of these pathways (e.g. antibody against neuregulin and Iressa) block proliferation of NF2-deficient schwannoma cells (Stonecypher et al, 2006, J. Neuropathol. Exp. Neurol. 65:162-175; Hansen et al., 2006, Glia 53:593-600). Recent evidence from Drosophila indicates that Merlin can regulate abundance/turnover of many signaling and adhesion receptors such as Notch, the EGF receptor, Patched, Smoothened, E- cadherin, and Fat. Loss of merlin results in accumulation of these cell surface receptors and activation of the associated signaling pathways (e.g. the EGFR pathway and the Wingless pathway) (Maitra et al, 2006, Curr. Biol. 16(7):702-709).

[0012] In addition to cell surface receptors, Merlin has been shown to interact with downstream components of various signaling pathways, including Rac-PAK (p21 -activated kinase) pathway. Rac is a member of the Rho family of small GTPases, which organize the actin cytoskeleton and control many cellular processes such as cell proliferation, transformation, and cell motility (Etienne-Manneville and Hall, 2002, Nature. 420(6916): 629-635; Sahai and Marshall, 2002, Nat. Rev. Cancer 2(2): 133-142). PAK can phosphorylate S518 of Merlin (Xiao et al, 2002, J. Biol. Chem. 277: 883-886; Kissel et al, 2002, J. Biol. Chem. 277(12): 10394-10399) which leads to conformational change and loss of growth-suppressing activity (Shaw et al, 1998, J. Biol. Chem. 273(13): 7757-7764; Shaw et al, 2001 , Dev. Cell. 1 (1): 63-72). Merlin can also act as a negative regulator of Rac-PAK signaling (Shaw et al, 2001 , Dev. Cell. 1 : 63-72; Kissil et al, 2003, MoI. Cell. 12:841 -849; Lallemand et al., 2003, Genes Dev. 17: 1090-1 100; Hirokawa et al., 2004, Cancer J. 10: 20- 26). Loss of Merlin results in the inappropriate phosphorylation and activation of PAK. Over-expression of Merlin inhibits PAK activation and blocks Rac-induced transformation. (Shaw et al, 2001 , Dev. Cell. 1 (1 ): 63-72; Kissil et al, 2003, MoI. Cell. 12(4): 841-849). Preliminary evidence indicates that loss of Merlin also leads to activation of the Ras/Raf/Mek/Erk pathway and PI3K-Akt pathway (Rangwala et al, 2005, J. Biol. Chem. 280(12):1 1790-1 1797; our preliminary data). A recent study from Drosophila has proposed that Merlin and a related protein expanded function upstream of the Hippo signaling pathway to regulate cell proliferation and apoptosis (Hamaratoglu et al, 2006, Nat. cell biol. 8:27-36; Willecke et al, 2006. Curr Biol. 16(21 ):2090-2100). [0013] The link between Merlin and growth factor receptor signaling indicates that growth factor receptors may play direct roles in NF2-associated tumor formation and progression. However, possible involvement of Merlin with multiple signaling pathways presents a challenge in developing drugs for the treatment of NF2. Neurofibromatosis type 1

[0014] NFl is one of the most common single gene disorder to affect the human nervous system, with an incidence of 1 in 3500 individuals (Sorensen SA, Mulvihill JJ, Nielsen A. Ann N Y Acad Sci 1986;486:30-7.). NFl affects approximately 1.5 million people worldwide and there is no racial, ethnic, or geographic predilection for the disease. NFl is an autosomal dominantly inherited genetic disorder with frequent germline deletion or loss-of- function mutations of the NFl gene, and is caused by mutation in the NFl gene, which encodes Neurofibromin, a tumor suppressor. Neurofibromin shares a region of similarity with the pi 20RasGAP protein, therefore functioning as a negative regulator of the Ras pathway. A high spontaneous mutation rate (50%) at the NFl locus and the substantial variability of its expression ensure that the disorder is unlikely to decrease significantly in the population due to genetic screening.

[0015] The signs of NFl include cafe-au-lait macules, skin freckling, skeletal defects, learning disability, Lisch nodules, deπnal and plexiform neurofibromas (most common), benign tumors of the brain or other organs (e.g. optic pathway astrocytomas, optic neuromas, optic gliomas, cerebral astrocytomas, cerebral gliomas, ganglioneuromas, ependymomas, pheochromocytomas and ganglioneuromas), and malignant neoplasms (e.g. rhabdomyosarcomas, neurofibrosarcomas or malignant peripheral nerve sheath tumors C¹MPNST^"') or malignant schwannomas) (Korf BR. J Child Neurol 2002; 17(8):573-7; discussion 602-4, 46-51.) Children affected by NFl also have increased risk for developing a rare form of leukemia-juvenile myelomonocytic leukemia (JMML) (Stiller CA, Chessells JM, Fitchett M. Br J Cancer 1994;70(5):969-72.). Dermal neurofibromas, subdermal neurofibromas, plexiform neurofibromas and MPNSTs are primarily derived from Schwann cells or their progenitors. Optic gliomas and astrocytomas are derived from astrocytes. Pheochromocytomas are derived from neural crest components (as are neurofibromas and MPNSTs).

[0016] The typical characteristic of NFl is the neurofibroma, of which there are clinically and histologically distinct types. Ninety-five% of patients have discrete benign neurofibromas within the dermis which may develop at any time in life, but their numbers are usually small before puberty. The total number of neurofibromas seen in adults varies from just a few to hundreds or even thousands. These tumors may cause disfigurement, chronic pain and pruritus. Certain patients may develop some of the same disfiguring symptoms that are associated with Elephant Man's disease, a separate disorder originally thought to be NFl . Plexiform neurofibromas may be congenital and are present in 30% of patients with NFl . These tumors represent a major cause of morbidity in NFl . They affect long portions of nerves and infiltrate the nerve and surrounding tissue, resulting in disfiguration and neuralgic complications. In about 2—5% of patients, plexiform neurofibromas transform to malignant peripheral nerve-sheath tumors, which have a significant mortality rate. Although NFl is usually not a lethal disorder, affected individuals often face a lifetime of morbidity and disfigurement.

[0017] The Nfl gene was identified in 1990 (Wallace et al. 1990 Science 249:181-186; Cawthon et al. 1990 Cell 62:193-201) and its gene product, neurofibromin, is a 250 kD protein of 2818 amino acids that has a catalytic domain related to the GTPase-activating protein (GAP) domain of pl20RasGAP (Marchuk et al., 1991 Genomics 1 1 :931-940; Gutmann et al., 1991. Proc. Natl. Acad. ScL U. S. A. 88: 9658-9662; DeClue et al., 1991. Proc. Natl. Acad. ScL U. S. A. 88:9914-9918; Martin et al., 1990. Cell 63:843-849; Xu et al., 1990. Cell 63: 835-841 ; Xu et al., 1990. Cell 62: 599-608). Loss of Nfl in human neurofibromas, MPNSTs, leukemias, and tumor-derived cell lines results in the elevation of Ras-GTP levels and activation of Ras-Raf-Mek-Erk2 and other MAP kinase pathways (Guha et al., 1996 Oncogene 12: 507-513; Bollag et al., 1996. Nat. Genet. 12:144-148; Basu et al. 1992. Nature 356: 713-715; DeClue et al., 1992 Cell 69:265-273). For example, Ras-GTP levels from a few NFl MPNST-derived cell lines ST88-14, 88-3 and 90-8 are much higher compared to other cell lines with normal neurofibromin. These cell lines also have activated downstream MAP kinase pathways. In addition, cell proliferation and soft agar growth of ST88-14 can be inhibited by injection of an antibody against Ras and expression of the GAP domain of neurofibromin, respectively. Therefore, controlling Ras pathway activity in these cells is important in blocking the transformation properties. HSP90 and HSP90 Inhibitors/Modulators

[0018] The heat shock protein 90 (HSP90) is an ATP-dependent molecular chaperone whose function is to ensure the proper folding and stability of a number of its client proteins such as kinases and transcription factors (Pearl and Prodromou, 2001 Adv. Protein Chem. 59: 157- 186). HSP90 belongs to the ATPase superfamily and consists of three protein domains: the

N-terminal ATPase domain, a middle domain responsible for client protein binding, and a C-terminal dimerization domain which also contains a weak ATP-binding domain (Pearl and

Prodromou, 2001 Adv Protein Chem. 59: 157-186). Four genes of the HSP90 family are found in humans and their gene products have different cellular locations. The two major cytoplasmic isoforms are HSP90 alpha and HSP90 beta (Hickey et al., 1989, MoI Cell Biol. 9: 2615-2626). Other major isoforms are GRP94 in the endoplasmic reticulum (Argon and Simen, 1999, Semin. Cell Dev. Biol. 10: 495-505) and TRAP1/HSP75 in mitochondria (Felts et al., 2000, J. Biol. Chem. 275: 3305-12). HSP 90 is found to be part of a series of dynamic multiprotein complexes made of co-chaperones including HSP70, HSP40, and Hop. Hydrolysis of ATP causes HSP90 to alter its conformation and allows other co-chaperones such as p23, CDC37, or imunophilins to associate with HSP90 to form a mature complex, which catalyzes the folding and maturation of the client proteins (Pearl & Prodromou, 2000, Curr. Opin. Struct. Biol. 10: 46-51.). The adaptor co-chaperone protein CDC37 mediates interactions between HSP90 and kinases (Pearl, 2005, Curr. Opin. Genet. Dev. 15:55-61 ; Roe et al., 2004, Cell 1 16: 87-98.).

[0019] There are over one hundred HSP90 client proteins reported in the literature (Solit and Rosen, 2006, Curr. Top. Med. Chem. 6:1205-14). Major HSP90 client proteins include steroid hormone receptors such as the androgen, estrogen and glucocorticoid receptors (AR, ER, and GR) (Whitesell and Cook, 1996, MoI. Endocrinol. 10: 705-712; Segnitz and Gehring, 1997, J Biol Chem. 272(30):l 8694-701 ; Czar et al., 1997 Biochemistry. 1997, 36:7776-85), tyrosine and serine/threonine kinases such as HER2 (ErbB2) (Munster et al., 2002, Cancer Res. 62: 3132-3137.), the insulin-like growth factor-1 receptor (IGF-IR) (Sepp-Lorenzino et al., 1995, J. Biol. Chem. 270: 16580-16587.), Met (Webb et al., 2000, Cancer Res. 60: 342- 349.), Flt-3 (Yao et al., 2003, Clin. Cancer Res. 9: 4483-4493.), ZAP70 (Castro et al., 2005, Blood 106: 2506-2512.), Src family kinases (Bijlmakers and Marsh, 2000, MoI Biol Cell. 1 1 :1585-1595.) Raf-1 (Schultc et al., 1995, J. Biol. Chem. 270: 24585-24588.), cyclin- dependent kinases 4 and 6 (Cdk4/6) (Stepanova et al., 1996, Genes Dev. 10: 1491-1502.), MLK3 (Zhang et al., 2004, J. Biol. Chem. 279: 19457-19463.), and Akt (Basso et al., 2002, J. Biol. Chem. 277: 39858-39866.), mutant proteins including v-Src (Xu et al., 1993, Proc. Natl. Acad. Sci. USA 90: 7074-7078: Whitesell et al., 1994, Proc. Natl. Acad. Sci. USA 91 :8324- 8328), mutant EGFR (Shimamura et al., 2005, Cancer Res. 65: 6401 -6408.), mutant B-Raf (da Rocha Dias et al., 2005, Cancer Res. 65: 10686-10691 ; Grbovic et al., 2006, Proc. Natl. Acad. Sci. USA 103: 57-62.), Bcr-Abl (Gorre et al., 2002, Blood 100: 3041 -3044; Nimmanapalli et al., 2001 , Cancer Res. 61 : 1799-1804.) and mutant p53 (Whitesell et al., 1998, MoI. Cell Biol. 18: 1517-1524.), and other proteins such as HIF-I alpha (Isaacs et al, 2002, J. Biol. Chem. 277: 29936-29944; Mabjeesh et al., 2002, Cancer Res. 62: 2478-2482.), Mdm2 (Peng et al., J. Biol. Chem. 276: 40583-40590.), and HSF-I (Zou et al., 1998, Cell 94: 471-480.). Many of these HSP90 client proteins are important in controlling cell growth and proliferation, differentiation, and cell survival. This is a putative rationale for the use of HSP90 inhibitors in the treatment of cancer. This subject has been extensively reviewed in the recent literature (Chiosis and Neckers, 2006, ACS. Chem. Biol. l(5):279-284; Janin, 2005, J. Med. Chem. 48(24):7503-7512; Sharp and Workman, 2006, Adv. Cancer Res. 95:323-348; Solit and Rosen, 2006, Curr. Top. Med. Chem. 6(1 1):1205-1214). The identification of specific HSP90 clients that are important for the growth of specific cancer types is an active area of research.

[0020] Two structurally unrelated natural products, geldanamycin and radicicol, were isolated in 1970 from Streptomyces hygrocopicus and in 1953 from the fungus Monosporium bonorden, respectively. Geldanamycin is a benzoquinone-based ansamycin antibiotic, and radicicol is a macrocyclic lactone antibiotic. They were believed to be kinase inhibitors initially and later found to inhibit HSP90 function via the interaction with the N-terminal

ATP binding domain of HSP90 (DeBoer et al., 1970, J. Antibiot. 23: 442-447, Roe et al .,

1999, J. Med. Chem. 42:260-266; Schulte and Neckers, 1998, Cancer Chemother. Pharmacol. 42:273-279; Prodromou et al., 1997, Cell 90:65-75; Whitesell et al., 1994, Proc. Natl. Acad. Sci. U. S. A. 91 :8324-8328). More compounds have been found to inhibit the function of HSP90 and are generally referred to as HSP90 inhibitors. Most HSP90 inhibitors inhibit the intrinsic ATPase activity by binding to the N-terminal nucleotide binding site of HSP90 and thus block the formation of the mature complex between HSP90, co-chaperones, and the client proteins since the formation of the mature complex is dependent on ATP hydrolysis. The client proteins are then degraded through the ubiquitin-proteasome degradation pathway (Connell et al., 2001 , Nat. Cell Biol. 3: 93-96.). The coumarin antibiotic novobiocin binds to the C-terminal ATP-binding site of HSP90 but with a very weak activity to degrade HSP90 client proteins (Marcu et al., 2000, J. Natl. Cancer Inst. 92:242-248; Marcu et al., 2000, J. Biol. Chem. 275:37181 -37186).

[0021] Both geldanamycin and radicicol demonstrate good cellular potency but are not suitable for clinical development. Geldanamycin has severe hepatotoxicity and radicicol is not stable in serum thereby having no in vivo anti-tumor activity (Agatsuma et al., 2002, Bioorg. Med. Chem. 10:3445-3454; Soga et al., 2003, Curr. Cancer Drug Targets, 3:359-369). Thus, analogs of radicicol, such as oxime derivatives of radicicol, and analogs of geldanamycin, such as 17-(Allylamino)-17-demethoxygeldanamycin (17-AAG), the more

water soluble analogue 17-demethoxy, 17-(2-dimethylamino) ethylamino geldanamycin

(17-DMAG), and hydroquinone analogue of 17-AAG, have been synthesized and tested.

These analogs generally exhibit good efficacy at tolerated doses in in vitro studies and in vivo animal xenograft models (Ikuina et al., 2003, J. Med. Chem., 46:2534-2541 ; Ge et al., 2006, J. Med. Chem. 49:4606-4615; Maroney et al., 2006, Biochemistry, 45:5678-5685; Shiotsu et al., 2000, Blood, 96(6):2284-2291 ; Sydor et al., 2006, Proc. Natl. Acad. Sci. U.S.A. 103(46): 17408- 17413). Several geldanamycin analogs have entered clinical trials for the treatment of cancer. These agents have demonstrated promising results in several types of cancer (e.g. breast cancer, leukemia, melanoma, and etc.).

[0022] The clinical experience of 17-AAG has stimulated a search for new HSP90 inhibitors with better pharmacological properties and safety profiles. A number of HSP90 inhibitors in various compound classes have been developed as potential agents for cancer treatment. These include purine-based compounds (PCT publications WO/2006/084030; WO/2002/036075; US7,138,401 ; US20050049263; Biamonte et al., 2006, J. Med. Chem. 49:817-828; Chiosis, 2006, Curr. Top. Med. Chem. 6:1 183-1 191 ; He et al., 2006, J. Med. Chem. 49:381-390), pyrazole-based compounds (Rowlands et al., 2004, Anal. Biochem. 327:176-183; Dymock et al., 2005, J. Med. Chem. 48:4212-4215; PCT publication WO/2007/021966; WO/2006/039977; WO/2004/096212; WO/2004/056782; WO/2004/050087; WO/2003/055860; US7, 148,228), peptidomimetic shepherdin (Plescia et al., 2005, Cancer Cell 7:457-468; US publication 20060035837), and HSP90 inhibitors in other compound classes (PCT publications WO/2006/123165; WO/2006/ 109085; WO/2005/028434; US7,160,885; US7,138,402; US7,129,244; US20050256183; US20060167070; US20060223797; WO2006091963). Furthermore, small molecules that modulate HSP functions have been reported. For instance, HDAC inhibitors such as Trichostatin A, SAHA, and FK228 are capable of inhibiting deacetylation of HSP90 and thus modulating the function of HSP90 (Kovacs et al., 2005, Molecular Cell, 18: 601-607). Other molecules modulating the level of HSPs, such as HSP70 and HSP27 may also affect the function of the HSP90 complex (Zaarur et al., 2006, Cancer Res. 66(3): 1783-1791 ). None of these HSP90 inhibitors have previously been shown to inhibit the growth of NFl - or NF2- deficient tumor cells. [0023] Current treatments for NF2- and NFl -associated tumors consist of surgical removal and focused-beam radiation. Neither treatment is considered optimal. Most patients with NF2 and NFl require multiple surgical and/or focused beam radiation procedures during their lifetime. Since the tumors of NF2 most frequently lie on nerves near the brain and spinal cord, their surgical removal is not without risk. For instance, surgical removal of vestibular schwannomas typically results in complete hearing loss and frequent facial nerve damage. Focused-beam radiation also has a significant incidence of hearing loss and facial nerve damage. Accordingly, a strong need exists for safer treatment options for NF2 and associated tumors (e.g. schwannomas, meningiomas, and mesotheliomas) and NFl and associated tumors (e.g. dermal neurofibromas, subdermal neurofibromas, plexiform neurofibromas, MPNSTs, gliomas, astrocytomas, and JMML). The present invention provides a novel method for treating NF2 and related NF2-deficient tumors and NFl and related NFl -deficient tumors and their associated signs and symptoms by administering HSP90 inhibitors.

SUMMARY OF THE INVENTION

[0024] The present invention is also directed to methods of treating a patient diagnosed with NF2 or NFl by the administration of a therapeutically effective amount of at least one compound that inhibits or reduces the activity of HSP90 in the patient, and particularly in the patients NF2-defϊcient and NF-I -deficient tumor cells.

[0025] The present invention also is directed to methods of inhibiting the growth of NF2- deficient tumor cells or NF-I deficient tumor cells by contacting the NF2-deficient tumor cells, such as schwannoma cells, meningioma cells, and mesothelioma cells, or NF-ldeficient tumor cells, such as neurofibroma cells, MPNST cells, glioma cells, astrocytoma cells, and JMML cells with at least one compound that inhibits or reduces the activity of HSP90. [0026] In another aspect, the present invention is directed to methods of assaying test compounds for the treatment of NF2. Preferably, the methods comprise assaying NF2- deficient cells or NFl -deficient cells treated with a HSP90 inhibitor for degradation of HER2 (ErbB2), phospho-HER2, AKT, phospho-AKT, Raf, or phospho-Raf proteins.

BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 shows that 17-AAG (500 nM) causes degradation of both Akt and phospho- Akt in NF2-deficient mouse and human tumor cells. [0028] Figure 2A shows the time-course of degradation of ErbB2 and c-Raf and upregulation of HSP70 by 17-AAG (500 nM) in NF2-deficient mouse and human tumor cells. Figure 2B shows that various concentrations of 17-AAG or Radicicol induce degradation of ErbB2 and c-Raf and upregulation of HSP70 in N/2-/- Schwann cells.

[0029] Figure 3 shows IC50s of several HSP90 inhibitors on cell proliferation of NF2- defϊcient mouse and human tumor cells.

[0030] Figure 4 shows IC50s of Trichostatin A (TSA) on cell proliferation of NF2-deficient mouse and human tumor cells.

[0031] Figure 5 shows that 17-AAG inhibits the formation of foci-like structures in Nf2-/- mouse Schwann cells.

[0032] Figure 6 shows that 17-DMAG delays the growth of N/2-/- mouse Schwann cell tumors in nude mice.

[0033] Figure 7 shows the pharmacodynamic markers in Np.-/- mouse Schwann cell tumors in vivo treated with vehicle or 17-DMAG.

DETAILED DESCRIPTION OF THE INVENTION

[0034] Tumors in NF2 and NFl patients are unique in that they are slow growing tumors. Both NF2 and NFl tumors have mutations or loss of heterozygosity in tumor suppressor genes although the tumor suppressor genes are different- NF2 or NFl genes, respectively. The inventors of the present invention have discovered that inhibitors of HSP90 potently blocked the proliferation of NF2-deficient and NFl -deficient tumor cells and also delay the growth of NF2-deficient and NFl -deficient tumors in mice. Merlin regulates the abundance and turnover of multiple cell surface receptors and interacts with multiple pathways. Many of these proteins are client proteins of HSP90. For instance, ErbB2 and other receptor tyrosine kinases, AKT, and Raf are well-established client proteins of HSP90. In addition, aberrant activation of the PI3K/AKT pathway has been found in human schwannomas from NF2 patients (as compared to normal nerves), in human NF2-deficient tumor xenografts (e.g. meningiomas and mesotheliomas), and in mouse Nf2-deficient Schwann cell tumors (reference is made to a PCT application entitled ''Treatment of Neurofibromatosis with Inhibitors of a Signal Transduction Pathway^" referenced as Attorney Docket No. NEXG-005- 01 WO, filed on June 4, 2007, which is incorporated in its entirety by reference). Neurofibromin is a negative regulator of Ras. Raf, the direct downstream effector of Ras, is a well-known client protein of HSP90. Neurofibromin has also been shown to regulate AKT. Therefore, a compound that inhibits HSP90 will likely be able to reduce the amount of AKT and other HSP90 client proteins such as ErbB2, IGF-IR, and Raf in the NF2-deficient cells or NFl -deficient cells. Reduction of the amount or activity of these proteins may be useful to reduce or stabilize the proliferation of NF2-deficient cells or NFl -deficient cells or to cause apoptosis of NF2-deficient cells or NFl -deficient cells. A compound that inhibits the activity of HSP90 is a compound that directly binds to the HSP90 protein or modifies the HSP90 protein post-translationally or regulate the transcription of HSP proteins such as HSP70 and HSP27 (Zaarar et al., 2006, Cancer Res. 66(3):1783-1791). For instance, HSP90 can be acetylated and inactivated by histone deacetylase (HDAC) inhibitors (Kovacs et al., 2005, MoI. Cell 18(5):601-607; Fuino et al., 2003, MoI. Cancer Ther. 2:971-984; Aoyagi and Archer, 2005, Trends Cell. Biol. 15(1 1):565-567). For this reason, HSP90 inhibitory compounds are determined to be useful for the treatment of NF2-deficient tumors and NFl- deficient tumors which may not respond well to traditional chemotherapy and other cancer therapies which target fast growing and heterogeneous cancer cells. NF2- Associated Tumors

[0035] Patients with neurofibromatosis typc-2 (NF2) have NF2-deficient tumors. This genetic characteristic, i.e., inactivation of the NF2 gene, differentiates tumors found in NF2 patients from genetically heterogeneous tumors such as breast and colon cancer tumors. For instance, NF2 patients have NF2 -deficient meningiomas whereas some non-NF2-deficient meningiomas may contain mutations in many different oncogenes or tumor suppressor genes. [0036] As used herein, "NF2-deficient tumors^" refer to tumors which contain a nonfunctioning NF2 gene. A non-functioning NF2 gene can be the result of a one or more insertion or deletion mutations within the NF2 gene, for instance, missense or nonsense mutations, mutations in the promoter or enhancer or introns that lead to no/low expression of the NF2 gene, or the deletion of the entire NF 2 gene. NF2-deficient tumors are found in mesotheliomas and in patients with NF2, and include schwannomas, meningiomas, and other tumors associated with the nervous system. NF2-deficient tumors are also found in all patients with sporadic schwannomas and in 50%-70% of patients with meningiomas. [0037] The presence of NF2-deficient bilateral vestibular schwannomas, i.e., Schwann cell tumors, is a hallmark of NF2. The methods of the present invention can be used to inhibit the growth and/or kill NF2-deficient schwannoma cells, including those associated with vestibular schwannomas, spinal cord and other peripheral nerve schwannomas and sporadic schwannomas. Merlin and signaling proteins and pathways

[0038] As used herein, "NF2-deficient tumors^" refer to tumors which contain a nonfunctioning NF2 gene. Merlin interacts with or regulates, but is not limited to, proteins and pathways such as Paxillin/lntegrin-βl/ErbB2, EGFR, Patched/Smoothened, HRS, CD44, E- Cadherin, Fat, EBP50/NHE-RF/PDGFR, Wingless, Notch, Rac-PAK, PI3K-AKT, Ras-Raf- Mek-Erk2, Hippo pathways, and downstream proteins thereof. Figure 1 is a schematic of involvement of Merlin with multiple cell surface proteins and signaling pathways. Targeting multiple proteins or pathways may be necessary for treating NF2. NFl- Associated Tumors

[0039] Patients with neurofibromatosis type- 1 (NFl) have NFl-deficient tumors. This genetic characteristic, i.e., inactivation of the NFl gene, differentiates tumors found in TVF/ patients from genetically heterogeneous tumors such as breast and colon cancer tumors. For instance, tumors found in NFl patients all have NFl gene mutations whereas patients with other cancers have mutations in different genes or overexpression of different genes. [0040] As used herein, '"NFl-deficient tumors^" refer to tumors which contain a non- functioning NFl gene. A non-functioning NFl gene can be the result of one or more insertion or deletion mutations within the NFl gene, for instance, missense or nonsense mutations, mutations in the promoter or enhancer or introns that lead to no/low expression of the NFl gene, or the deletion of the entire NFl gene. NFl-deficient tumors are found in patients with NFl , and include dermal, subdermal, plexiform neurofibromas, and MPNST and other tumors associated with the nervous system. NFl -deficiency also predisposes individuals to a rare form of leukemia, JMML.

[0041] NFl diagnosis is confirmed by fulfilling NIH clinical criteria or by finding an NFl mutation with mutational analysis. The methods of the present invention can be used to inhibit the growth and/or kill NFl -deficient tumors, including dermal, subdermal, plexiform neurofibromas, MPNST, gliomas, astrocytomas, pheochromocytomas and JMML. Method of inhibiting the growth of NF2 and NFl tumor cells

[0042] The present invention includes methods of inhibiting the growth of NF2-deficient and/or NFl -deficient tumor cells by contacting, i.e., treating, the NF2-deficient or NFl - deficient tumor cells with inhibitors of HSP90. The present invention also includes methods of decreasing proliferation of NF2-deficient or NFl -deficient tumor cells by contacting the cells with an inhibitor of HSP90. [0043] In one embodiment, inhibition of the growth of NF2 or NFl cells is determined by comparing a sample of NF2-deficient or NFl -deficient tumor cells treated with an inhibitor of HSP90 to a control, such as a sample of untreated NF2-deficient or NFl -deficient tumor cells or a sample of cells treated with a known inert compound. Prior to contacting cells with an inhibitor of HSP90, both samples of NF2-deficient cells or NFl -deficient cells (treated and control) should consist of approximately the same number of cells and be of the same cell type, e.g., NF2-deficient schwannomas or NFl -deficient MPNST cells. NF2-deficient tumor cells or NFl -deficient tumor cells treated with an inhibitor of a HSP90 protein may decrease in number by at least about 10%, at least about 20%, at least about 30%, at least about 40%, at least about 50%, at least about 60%, at least about 70%, at least about 80%, at least about 90%, or about 100% following compound treatment compared to the control. [0044] HSP90 functions as a chaperone for its client proteins as part of dynamic multiprotein complexes, here define as "HSP90 complexes^" or "HSP90 chaperone machineries, which consist of co-chaperones such as HSP90, HSP70, HSP27, HSP40, HOP, p23, and CDC37 and individual client protein. These multimeric chaperone/co-chaperone complexes are quite dynamic and involve a series of cycles of association and dissociation of several co- chaperones with HSP90 and/or client proteins.

[0045] As used herein, "a HSP90 inhibitor,^" "a HSP90 inhibitor compound," "a HSP inhibitory compound,^" "an inhibitor compound^", or "an inhibitor'^" refers to a substance that inhibits or reduces the growth of or number of NF2-deficient tumor cells or NFl -deficient tumor cells by inhibiting HSP90 function in these cells. Any compound that modulates the activity of HSP90, i.e., a HSP90 modulator, may also be used to inhibit the growth of NF2- deficient tumor cells. For example, a HSP90 modulator may modulate HSP90 by inhibiting or down-regulating, i.e., reducing, the activity of one or more proteins of the HSP90 complex. [0046] In one embodiment of the present invention, biological agents or molecules that inhibit or reduce the activity of the HSP90 complex may also be used to inhibit the growth of NF2-deficient or NFl -deficient tumor cells. Examples of the biological agents or molecules of the present invention, include, but are not limited to antibodies, peptides, siRNAs, antisense nucleic acids, and any combinations thereof.

[0047] Inhibition by a HSP90 inhibitor can occur through a reduction in the capability of the HSP90 protein or complex to assist its client proteins to function in or to activate a signaling pathway. The HSP90 inhibitor may reduce the amount of total or phosphorylated forms of specific client proteins of HSP90 which in turn inhibits the activity of the downstream pathways of these client proteins. The HSP90 inhibitor/modulator can upregulate the amount of the HSP70 protein and other HSP proteins in the HSP90 complex. HSP90 function can be inhibited or modulated, for example, such as by binding of a compound as disclosed herein to HSP90 or by modifying the HSP90 protein postranslationally. Also, such as by inhibition of a kinase activity of a protein, by inhibition of dimerization of a protein, inhibition of DNA binding of a protein, or inhibition of transactivation of a protein. HSP90 inhibitors can inhibit one or more proteins in the HSP90 complex by an antibody specific for it or by employing antisense, siRNA, or ribozyme technologies to reduce the level of mRNA coding for the protein.

[0048] The HSP90 inhibitors or modulators useful for the present invention include, but are not limited to radicicol and its analogs, benzoquinone-based ansamycin antibiotics, purine scaffold-based HSP90 inhibitors, pyrazole or imidazole scaffold-based HSP90 inhibitors, tetrahydroindolone- or tetrahydroindazolone-based HSP90 inhibitors, novobiocin and its analogs, and any combinations thereof.

[0049] Radicicol, a macrocyclic lactone antibiotic, has been shown to inhibit the function of HSP90. To further investigate the biological mechanism of radicicol and its analogs in regulating HSP90 and establish the fundamental structure-activity relationship, a number of radicicol analogs have been synthesized and studied. The term "radicicol analogs" or "radicicol derivatives^" as used herein denotes macrocyclic lactone compounds that are structurally similar to radicicol. Specifically, the "radicicol analogs^" or "radicicol derivatives" refer to compounds of fused bicyclic ring structure wherein a six-membered aromatic ring shares two carbon atoms with a 12- to 16-membered non-aromatic ring containing a lactone group and at least one olefin group in the core of the 12- to 16- membered ring. The radicicol analogs/derivatives may have one or more substituents on the six-membered aromatic ring or the 12- to 16-membered non-aromatic ring. It is noted that the terms "analog" and "derivative" are used interchangeably in the present application. [0050] A number of radicicol analogs have been disclosed in patent publications including WO 96/33989, WO 98/18780, WO 99/55689, US 7, 1 15,651 , US 5,731 ,343, and US 5,077,165, all of which are herein incorporated by reference in their entirety. Radicicol and its representative analogs are shown in Scheme 1. [0051] SCHEME 1

Cyclopropane Radicicol

of Radicicol

(compound 9b, Ikuina. 2003, J. Med. Chem., 46, 2534)

[0052] In one embodiment of the present invention, preferred radicicol analogs have the structure represented by Formula (I):

Formula (I)

[0053] wherein R¹, R², R³, and R⁴ are each independently hydrogen, halogen, hydroxyl, substituted or unsubstituted alkoxy, substituted or unsubstituted alkyl, substituted or unsubstituted alkenyl, substituted or unsubstituted alkynyl, cyano, amino, N-alkyl amino, N,N-dialkyl amino, heteroaliphatic, or heteroalicyclic;

[0054] R⁵ is hydrogen, substituted or unsubstituted alkyl, substituted or unsubstituted alkenyl, substituted or unsubstituted alkynyl, substituted or unsubstituted aryl, substituted or unsubstituted alkylaryl, substituted or unsubstituted heteroaryl, substituted or unsubstituted alkylheteroaryl; [0055] A and B together represent

[0056] D and E together, and G and H together, each independently represent

(e) R¹⁰ R¹¹ or (f) R¹² R¹³ , [0057] wherein R⁶, R⁷, R¹⁰, and R^{1 1} are each independently hydrogen, halogen, or substituted or unsubstituted alkyl, and R⁸, R⁹, R¹², and R¹³ are each independently hydrogen, halogen, hydroxyl, substituted or unsubstituted alkoxy, substituted or unsubstituted alkyl, substituted or unsubstituted alkenyl, substituted or unsubstituted alkynyl, cyano, amino, N-alkyl amino, or N,N-dialkyl amino, heteroaliphatic, orheteroalicyclic; [0058] M and L together represent

[0059] wherein R¹⁴ and R¹⁵ are each independently hydrogen or substituted or unsubstituted alkyl;

[0060] L and Y together represent C=O, C=S, -CH2-, =CH-, -CH-CH(R^Y)2, C=C(R^Y)2,

CH-OR^Y, CH-SR^Y, CH-N(R^Y)2, CH-N(R^Y)-(C=O)-R^Y, C=N-O-R^Y, CH-N=O, C=C(R^Y)-

N(R^Y)2, C=N-R^Y, C=N-N(R^Y)2, O-(C=O)-R^Y, O-(C=O)-OR^Y, -CH-CH(R^Y)-(C=O)-N(R^Y)2,

[0061] wherein each R^γ is independently hydrogen, aliphatic, heteroaliphatic, alicyclic, heteroalicyclic, aryl, heteraryl, alkylaryl, or alkylheteraryl;

[0062] with the following provisos:

[0063] (i) when M-L is (g), then Y is attached to L via a monovalent bond or a divalent bond; and

[0064] (ii) when M-L is (h), then Y is attached to L via a monovalent bond.

[0065] In one preferred embodiment, R and R are each independently substituted or unsubstituted alkoxy, R^" is hydrogen, and R is halogen.

[0066] In another preferred embodiment, R⁶, R⁷, R⁸, R⁹, R¹⁰, R¹ ', R¹², R¹³, R¹⁴, and R¹⁵ are hydrogen.

[0067] In another preferred embodiment, R⁸ and R⁹, are each independently hydroxyl, halogen, or substituted or unsubstituted alkoxy.

[0068] In yet another preferred embodiment, L and Y together represent C=O or C=N-O-

R^γ.

[0069] As used herein, the term "'aliphatic^" denote an organic moiety containing only carbon and hydrogen atoms and having the carbon atoms linked in open chains that can be straight or branched. Examples of aliphatic compounds include, but are not limited to alkanes, such as, propyl, butyl, and hexyl; alkenes, such as, butylene and hexylene; and alkynes, such as butyne. The term "'alicyclic" denote an organic moiety containing only carbon and hydrogen atoms and having at least some carbon atoms linked in ring structure. That is, "alicyclic" is both aliphatic and cyclic. Alicyclic contains one or more all-carbon rings which may be either saturated or unsaturated, but not aromatic. When an alicyclic contains more than one rings, the rings can be separated, fused or bridged. Examples of alicyclic compounds include, but are not limited to cycloalkanes, such as, cyclopropane, cyclobutane, and cylcohexane; and cycloalkenes, such as, cyclobutene and cylcohexene. [0070] By "heteroaliphatic^'', it is meant an organic moiety containing carbon, hydrogen, and hetero atoms and having the carbon atoms linked in open chains that can be straight or branched. "Heteroalicyclic" is both heteroaliphatic and cyclic. Examples of the heteroatom in '"heteroaliphatic" and "heteroalicyclic"' include, but are not limited to oxygen, nitrogen, halogen, sulfur, phosphor, and any combinations thereof. When a heteroalicyclic contains more than one ring, the rings can be separated, fused or bridged. Heteroaliphatic and heteroalicyclic may contain functional groups including, but are not limited to: ketone, lactone, ester, amide, lactam, imine, carboxylic acid, carboxylic halide, anhydride, thioether, urea, ether, carbamate, isocyanate, oxime, hydrazine, hydrozone, and any combinations thereof.

[0071] One well-known class of HSP90 inhibitors are benzoquinone-based ansamycin antibiotics, the structure of which typically contain a 1 ,4-benzoquinone ring fused with a 18- to 20-membered non-aromatic ring containing a lactam group and at least one olefin group in the core of the 18- to 20-membered ring. (See, for example, WO 98/51702, which is herein incorporated by reference in its entirety) Some representative benzoquinone-based ansamycin antibiotics are shown in Scheme 2. [0072] SCHEME 2

Geldanamycin: R¹ = H, R² = H, R³ = OCH₃ Dihydroquinone derivative of 17-AAG

Herbimycin: R¹ = CH₃, R² = OCH₃, R³ = H 17-AAG: R¹ = H, R² = H, R³ = -NHCH₂CH=CH₂ 17-DMAG: R¹ = H, R² = H, R³ = -NHCH₂CH₂N(CH₃)₂

[0073] It has been reported that certain purine scaffold-based compounds are HSP90 inhibitors. (See, for example, WO 02/36705, WO 03/037860, and WO 2006/084030, all of which are herein incorporated by reference in their entirety) These purine scaffold-based HSP90 inhibitors typically have a structure wherein an adenine ring and a six-membered aryl or heteroaryl ring are linked through a linker which can be methylene, fluorinated methylene, sulfur, oxygen, nitrogen, carbonyl, imine, sulfϊnyl, or sulfonyl. Scheme 3 shows two compounds exemplifying the purine scaffold-based HSP90 inhibitors. [0074] SCHEME 3

[0075] Some pyrazole or imidazole scaffold-based compounds are known to inhibit HSP90. These pyrazole or imidazole scaffold-based HSP90 inhibitors are typically non-fused tricyclic compounds wherein two aryl or heteroaryl rings are attached to two adjacent positions (carbon or nitrogen atom) of a pyrazole or imidazole ring, respectively. (See, for example, WO 2007/021877, which is herein incorporated by reference in its entirety, or Vernalis Ltd, Bioorg Med Chem Lett, 2006, 16, 2543-2548, or Sharp et al., Molecular Cancer Therapeutics, 2007, 6, 1 198-121 1). Examples of pyrazole or imidazole scaffold-based HSP90 inhibitors are shown in Scheme 4. [0076] SCHEME 4

CCT018159 CCT0129397 VER49009

Compound 1 in Table 5 Compound 2 in Table 5 Compound 3 in Table 5 WO 2007/021877 WO 2007/021877 WO 2007/021877

[0077] Another class of HSP90 inhibitors are tetrahydroindolone and tetrahydroindazolone derivatives reported in WO 2006/091963, the disclosure of which is herein incorporated by reference in its entirety. These tetrahydroindolone or tetrahydroindazolone based HSP90 inhibitors generally have a structure wherein a substituted aryl group is directly attached to the nitrogen atom of a tetrahydroindolone or tetrahydroindazolone. Scheme 5 shows certain examples in WO 2006/091963. [0078] SCHEME 5

Example 3 Example 11

WO 2006/091963 WO 2006/091963

[0079] The aminoglycoside antibiotic, Novobiocin, has also been reported to inhibit HSP90. (See, for example, Yu et al., J. Am. Chem. Soc, 2005, 127, 12778-12779) The structure of Novobiocin is shown in Scheme 6. [00801 SCHEME 6

(0081] Many client proteins of HSP90 are kinases which are involved in phosphorylation cascades. For this reason, presence and/or activity of a client protein of HSP90 can be assessed by measuring the phosphorylation of the protein and/or a downstream protein. Inhibition of phosphorylation or hypophosphorylation is an indication of a decrease or inhibition of activity of a protein. In one embodiment, the proliferation of NF2-deficient tumor cells or NFl -deficient cells can be reduced or stabilized by the administration of a HSP90 inhibitory compound that inhibits or reduces the phosphorylation of one or more proteins of the PI3K/Akt pathway or Ras-Raf pathway including, but not limited to, Akt, mTOR, FKHR, GSK3, S6, S6K, Bad, Raf, Mek, and Erkl/2 proteins. [0082] In another embodiment of the invention, the proliferation of NF2-deficient or NFl- deficient tumor cells can be reduced or stabilized by the administration of a HSP90 inhibitory compound that reduces or degrades ErbB2 or phospho-ErbB2.

[0083] In another embodiment of the invention, the proliferation of NF2-deficient or NFl- deficient tumor cells can be reduced or stabilized by the administration of a HSP90 inhibitory compound that reduces or degrades other receptor tyrosine kinases.

[0084] The present invention is also directed to a pharmaceutical composition comprising a HSP90 inhibitor, or a pharmaceutically acceptable salt, solvent and/or ester thereof, and a pharmaceutically acceptable carrier or excipient. As used herein, the term "pharmaceutically acceptable" refers to a carrier, diluent, vehicle, excipient, and/or salt that is compatible with the other ingredients of the composition, and not deleterious to the recipient thereof. In one embodiment, the inhibitor compound can be in a water soluble formation or lipid soluble formulation as known in the art.

[0085] Growth of NF2-deficient or NFl -deficient tumor cells can be inhibited in vitro or ex vivo. NF2-deficient or NFl -deficient tumor cells can be primary cell culture cells or a tissue culture cell line cells. Cells can be mammalian cells, including, but not limited to, human, canine, rat and murine 7V/2-deficient or NfI -deficient tumor cells. For instance, methods of the invention include the use of jV/2-deficicnt mouse cells {e.g.. Schwann cells) or NF2- deficient human tumor cells (e.g., Schwann cells) or NfI -deficient mouse cells {e.g. Schwann cells and MPNST cells) or NFl -deficient human tumor cells (e.g. MPNST cells, astrocytoma cell, JMML cells). Cells can be confluent or subconfluent when contacted with an inhibitor of the H SP90 protein.

[0086] In another embodiment, NF2-deficient or NFl -deficient tumor cells are contacted with a compound in vivo. In this embodiment, a compound is administered to a subject with a NF2-deficient or NFl -deficient tumor. The subject can be any mammal, including, but not limited to, a human, canine, rat, mouse, and farm animals. The compound can be administered at the site of a NF2-deficient or NFl -deficient tumor or elsewhere in the body. [0087] NF2-deficient or NFl -deficient tumor cells can be contacted in vitro or ex vivo with very small amounts of compound to trigger inhibition of cell growth and/or resulting in cell death. For instance, NF2-deficient or NFl -deficient cells can be contacted with at least about .001 μM of compound, at least about .01 μM of compound, at least about .05 μM of compound, at least about 0.08 μM of compound, at least about 0.09 μM of compound, at least about 0.1 μM of compound, at least about 0.2 μM of compound, at least about 0.3 μM of compound, at least about 0.4 μM of compound, at least about 0.5 μM of compound, at least about 0.6 μM of compound, at least about 0.7 μM of compound, at least about 0.8 μM of compound, at least about 0.9 μM of compound, at least about 1 μM of compound, at least about 1.5 μM of compound, at least about 2 μM of compound or about 2 μM of compound to 10 μM of compound to inhibit cell growth and/or trigger cell apoptosis. Appropriate amounts of the compound to contact with the cells can be determined by persons skilled in the art to obtain the desired level of inhibition of cell growth or the corresponding amount of cell death. [0088] Inhibition of cell growth or cell death can be measured by methods known in the art. For instance, in vitro and ex vivo inhibition of cell growth and cell death can be measured by a cell proliferation assay and a cell apoptosis assay. Cell death or inhibition of proliferation can be measured in terms of the IC50 of the compound. In one embodiment, the IC50 of NF2-deficient tumor cells treated in vitro or ex vivo is at least about .001 μM, at least about .01 μM, at least about .05 μM, at least about 0.08 μM, at least about 0.09 μM, at least about 0.1 μM, at least about 0.2 μM, at least about 0.3 μM, at least about 0.4 μM, at least about 0.5 μM, at least about 0.6 μM, at least about 0.7 μM, at least about 0.8 μM, at least about 0.9 μM, at least about 1 μM, at least about 1.5 μM, at least about 2 μM, or about 2 μM to 10 μM. [0089] In another embodiment, NF2-deficient or NFl -deficient tumor cells are contacted with a HSP90 inhibitor compound in vivo. In this embodiment, a compound is administered to a subject with a NF2-deficient or NFl -deficient tumor. The subject can be any mammal, including, but not limited to, a human, canine, rat, mouse, and farm animals. The compound can be administered at the site of the tumor or elsewhere in the body.

[0090] When a compound is administered in vivo, it can be administered such that the serum levels mimic those levels found to cause inhibition of cell growth and/or cell death in vitro. In one embodiment, the HSP90 inhibitor compound contacts the NF2-deficient or NFl- defϊcient tumor cells with another agent. "Agent," "compound" and "molecule^" are used interchangeably herein and refer to a chemical or biological entity that can be used, for example, as a therapeutic. Agents can also be used to mitigate toxicity. For instance, a PAK inhibitor can be used in conjunction with a HSP90 inhibitor compound to inhibit cell growth or cause cell death.

[0091] A cytotoxic agent and a HSP90 inhibitor compound can also be contacted together with NF2-defϊcient or NFl -deficient tumor cells, either simultaneously or sequentially. In this embodiment, the cytotoxic agent, i.e., chemotherapeutic drug, can act synergistically with the HSP90 inhibitor compound to inhibit growth and kill NF2 -deficient or NFl -deficient tumor cells. Cytotoxic agents that can be co-administered with a HSP90 inhibitor compound are chemotherapy drugs known in the art. Methods of Treatment

[0092] The present invention provides methods of treating a subject diagnosed with neurofibromatosis type-2 or a condition associated with the loss of NF2 function (i.e., the loss of the protein, Merlin), including, but not limited to sporadic schwannomas, and other NF2 related tumors, such as sporadic meningiomas and sporadic mesotheliomas. The method comprises the administration to the subject a therapeutically effective amount of one or more HSP90 inhibitor compounds which inhibit or decrease the growth of one or more NF2- deficient tumors. "Subject" and "patient^" are used interchangeably herein, and refer to a mammalian subject to be treated, including, but not limited to, human patients. A subject can be diagnosed with NF2 by methods known in the art, including, but not limited to, a direct gene test and the bilateral occurrence of vestibular schwannomas. The methods of treatment are similar for a subject diagnosed with NFl or a condition associated with the loss of NFl function (i.e., the loss of the protein, neurofibromin).

[0093] As used herein, "therapeutically effective amount^" refers to an amount sufficient to inhibit the growth of one or more NF-2 deficient tumors or NFl -deficient tumors. "Inhibition^", as used herein, means that the size of a tumor stabilizes and does not increase. In one embodiment, the tumor may be reduced in size following administration of a HSP90 inhibitor compound. For instance, the tumor may be reduced in size at least about 10%, at least about 20%, at least about 30%, at least about 40%, at least about 50%, at least about 60%, at least about 70%, at least about 80%, at least about 90%, or about 100% compared to the size of the tumor prior to treatment, i.e., a baseline measurement. The inhibition of tumor growth can be assessed by methods known in the art, including, but not limited to, magnetic resonance imaging or a CAT scan.

[0094] As can be appreciated by a skilled artisan, a "therapeutically effective amount" will vary depending on the tumor load of the patient and the age, weight, and other conditions of the patient to be treated. Further, a therapeutically effective amount may vary based on the type of HSP90 inhibitor compound administered and pharmaceutical composition as well as the route of administration.

(0095] The methods of the present invention can be used to treat a variety of NF2-defϊcient tumors or NFl -deficient tumors. For instance, a HSP90 inhibitor compound can be administered to treat a vestibular schwannoma, for instance, a unilateral schwannoma or a bilateral schwannoma. Inhibition of the growth of these tumors and/or death of tumor cells can mitigate the symptoms associated with schwannomas, including but not limited to vestibular schwannomas. For instance, treatment with a HSP90 inhibitor compound may result in an improvement in hearing, tinnitus and/or balance.

[0096] The methods of the invention can be used to treat other types of NF2-deficient schwannomas as well or type of NFl -deficient tumors. For instance, administration of a HSP90 inhibitor compound can be used to treat a patient suffering from one or more spinal cord schwannomas/neurofibromas and other peripheral nerve schwannomas/neurofibromas and sporadic schwannomas/neurofibromas. Treatment of peripheral nerve tumors, including spinal cord tumors, can decrease a patient^'s pain. Further, neurological deficits associated with NFl may be reversible with HSP90 inhibitor compound treatment. [0097] In one embodiment of the invention, administration of a compound results in a decrease in a patient^'s tumor load. For instance, administration of a HSP90 inhibitor or a pharmaceutically acceptable salt, solvate, and/or ester thereof can result in at least about a 5%, at least about a 10%, at least about a 15%, at least about a 20%, at least about a 25%, at least about a 30%, at least about a 40%, at least about a 50%, at least about a 60%, at least about a 70%, at least about an 80%, at least about a 90%, or about a 100% decrease in tumor load.

[0098] A HSP90 inhibitor compound may be formulated for administration in a pharmaceutically acceptable earner or excipient in accordance with known techniques in the art. See, e.g., Remington, The Science And Practice of Pharmacy (9^th Ed. 1995). In the manufacture of a pharmaceutical composition according to the invention, the compound

(including the physiologically acceptable salts thereof) is typically admixed with, inter alia, an acceptable carrier. The carrier must, of course, be acceptable in the sense of being compatible with any other ingredients in the composition and must not be deleterious to the patient. The carrier may be a solid or a liquid, or both, and is preferably formulated with the compound as a unit-dose formulation, for instance, a tablet, which may contain from 0.01 or

0.5% to 95% or 99% by weight of compound. In one embodiment of the invention, the pharmaceutical composition administered to the patient contains more than one type of

HSP90 inhibitor.

[0099] Pharmaceutical compositions include those suitable for oral, rectal, topical, buccal

{e.g., sub-lingual), vaginal, parenteral (e.g., subcutaneous, intramuscular, intradermal, intraperitoneal, intravenous, etc.), topical {e.g., both skin and mucosal surfaces, including airway surfaces) and transdermal administration.

[00100] In one embodiment of the invention, the pharmaceutical composition is applied directly to the site of a NF2-deficient tumor or NFl -deficient tumor. For instance, the HSP90 inhibitor can be applied by local treatment which encompasses both topical treatment and intralesional or intradermal treatment at the site of the tumor. Therefore, the inhibitor can be injected into, topically applied onto or near a NF2 -deficient tumor or NFl -deficient tumor. In one embodiment of the invention, the inhibitor is applied intralesionally to NF2-deficient tumors or NFl -deficient tumors by methods known in the art.

[00101] Alternatively, a HSP90 inhibitor pharmaceutical composition can take the form of an implant. Such a composition can be surgically implanted at or near the site of a tumor for slow release of the HSP90 inhibitor.

[00102] In another embodiment of the invention, a pharmaceutical composition is administered by transcatheter arterial embolization by methods known in the art.

[00103] Pharmaceutical compositions suitable for oral administration may be presented in discrete units, such as capsules, cachets, lozenges, or tablets, each containing a predetermined amount of a HSP90 inhibitor; as a powder or granules; as a solution or a suspension in an aqueous or non-aqueous liquid; or as an oil-in-water or water-in-oil emulsion.

[00104] Pharmaceutical compositions suitable for buccal (sub-lingual) administration include lozenges comprising the active compound in a flavored base, usually sucrose and acacia or tragacanth; and pastilles comprising the compound in an inert base such as gelatin and glycerin or sucrose and acacia. [00105] Pharmaceutical compositions of the present invention suitable for parenteral administration comprise sterile aqueous and non-aqueous injection solutions of the active compound, which preparations are preferably isotonic with the blood of the intended recipient. These preparations may contain anti-oxidants, buffers, bacteriostats and solutes which render the formulation isotonic with the blood of the intended recipient. Aqueous and non-aqueous sterile suspensions may include suspending agents and thickening agents. [00106] In one embodiment of the invention, a pharmaceutical composition of the HSP90 inhibitor is applied topically. For instance, a pharmaceutical composition can be applied to the skin near a NF2-deficient tumor or a NFl -deficient tumor. Compositions suitable for topical application to the skin preferably take the form of an ointment, cream, lotion, paste, gel, spray, aerosol, or oil. Carriers which may be used include petroleum jelly, lanoline, polyethylene glycols, alcohols, transdermal enhancers, and combinations of two or more thereof.

[00107] Pharmaceutical compositions suitable for transdermal administration may be presented as discrete patches adapted to remain in intimate contact with the epidermis of the recipient for a prolonged period of time. Such compositions may be applied near or at the site of a NF2-deficient tumor or a NFl -deficient tumor. Formulations suitable for transdermal administration may also be delivered by iontophoresis (see, for example, Pharmaceutical Research 3 (6):318 (1986)) and typically take the form of an optionally buffered aqueous solution of the active compound. Suitable formulations comprise citrate or bis\tris buffer (pH 6) or ethanol/water and contain from 0.1 to 0.2M active ingredient. [00108] The present invention also includes methods of treating a subject with NF2 or NFl by administering a liposomal formulation of HSP90 inhibitors and salts thereof. The technology for forming liposomal suspensions is well known in the art. When the inhibitor is water-insoluble, the salt may be substantially entrained within the hydrophobic lipid bilayer which forms the structure of the liposome. The liposomes which are produced may be reduced in size, as through the use of standard sonication and homogenization techniques. The liposomal formulations containing the HSP90 inhibitors disclosed herein or salts thereof, may also be lyophilized to produce a lyophilizate which may be reconstituted with a pharmaceutically acceptable earner, such as water, to regenerate a liposomal suspension. [00109] Other pharmaceutical compositions may be prepared from HSP90 inhibitor compounds or salts thereof, such as aqueous base emulsions. In such an instance, the composition will contain a sufficient amount of pharmaceutically acceptable emulsifying agent to emulsify the desired amount of HSP90 inhibitor or salt thereof. Particularly useful emulsifying agents include phosphatidyl cholines and lecithin.

[00110] The therapeutically effective dosage of any specific HSP90 inhibitor for treatment of a NF2 -deficient tumor or a NFl -deficient tumor will vary from patient to patient, and will depend upon factors such as the age, weight, gender and condition of the patient and the route of delivery. As a general proposition, a dosage from about 0.01 or 0.1 to about 50, 100 or

500 mg/kg will have therapeutic efficacy, with all weights being calculated based upon the weight of the HSP90 inhibitor, including the cases where a salt is employed.

[00111] The methods of the invention include co-administering a HSP90 inhibitor with another therapeutic agent, either concurrently or sequentially. For instance, a HSP90 inhibitor pharmaceutical composition can be administered with a cytotoxic agent known in the art to inhibit tumor growth or kill the tumor(s). Co-administration of a HSP90 pathway inhibitor with a cytotoxic agent may reduce the toxic side-effects otherwise associated with the cytotoxic agent. Toxicity would be reduced because less cytotoxic agent would need to be administered to the patient to inhibit tumor growth or kill one or more tumors than if the cytotoxic agent were administered alone.

[00112] In addition to co-administration of a HSP90 inhibitor with a cytotoxic agent such a chemotherapy drug, a HSP90 inhibitor compound can also be administered with radiation therapy in combination. As with chemotherapy, administration of a HSP90 inhibitor with radiation therapy allows less HSP90 inhibitor and radiation therapy to be used for treatment, and thus, reduces the risk of toxic side effects.

[00113] HSP90 inhibitors can also be administered before or after surgical removal of a tumor to kill or inhibit the growth of any remaining NF2-deficient or NFl-deficient tumor cells. This embodiment is especially useful for tumors of the brain and spine where removing all NF2-deficient or NFl -deficient tumor cells could put the patient at risk for permanent nerve damage or even death.

[00114] In another embodiment, a HSP90 inhibitor is administered to a patient with a PAK inhibitor.

Methods of Screening for NF2 and NFl HSP90 Inhibitor Therapeutics

[00115] The present invention also includes methods of screening HSP90 inhibiting compounds for efficacious treatment of NF2 or NFl . For instance, the methods of the invention can be used to determine the efficacy of a compound in pre-clinical experiments.

This is useful because it can allow researchers to reduce the number of drugs to be tested for efficacious treatment of NF2 or NFl . The methods of the invention can also be used to repurpose existing drugs that were developed and/or are used for other indications. This is useful because such drugs presumably have established safety data and can thus be brought to market quicker and with less expense than uncharacterized compounds. [00116] As used herein, "efficacious treatment^"' means that a test compound results in the inhibition or reduction of cell growth. In one embodiment, efficacious treatment results in cell death or inhibition of proliferation. An efficacious treatment can be correlated with a reduction in the amount or activity of one or more client proteins of HSP90 or an increase in other HSP proteins such as HSP70. For instance, a reduction in the amount of ErbB2 protein leads to the reduction in the amount of phospho-ErbB2 and the activity of ErbB2 which can be correlated with the inhibition or reduction of growth of NF2-deficient cells. In addition, a reduction in the amount of AKT or phospho-AKT may lead to the reduction in the phosphorylation of mTOR, GSK3, FKHR, S6 and S6K which can also be correlated with the inhibition or reduction of growth of NF2-defϊcient cells or apoptosis of NF2-deficient cells. Moreover, a reduction in the amount of Raf may lead to the reduction in the activity of downstream MAP kinase signaling pathway which can be correlated with the inhibition or reduction of growth of NFl -deficient cells.

[00117] Methods known in the art can be used to assess whether a test drug reduces the activity of one or more client proteins of the HSP90 complex. Such assays can be conducted in vitro, ex vitro using cells or tumor specimens from human patients or animal models, or, in the case of animal models, in vivo (Roe et al., 2004, Cell 1 16: 87-98; Smith et al., 2005, Cancer Chemother. Pharmacol. 56:126-137; Banerji et al., 2005, Clin. Cancer Res. 1 1 :7023- 7032; Eiseman et al., 2005, Cancer Chemother. Pharmacol. 55: 21-32; Goβtz et al, 2005, J. Clin. Oncol. 23(6): 1078-1087; Solit et al., 2002, Clin. Cancer. Res. 8(5):986-993) [00118] In one embodiment of the invention, the ability of a drug to reduce the activity of a client protein (e.g. a kinase) of HSP90 or the downstream pathway of the client protein is assessed by contacting the proteins of the cells with an anti-phospho antibody specific for the particular protein. For instance, Western blots can be used by methods known in the art and can be probed with anti-phospho antibodies to phosphorylated AKT, phosphorylated ErbB2, phosphorylated GSK3, phosphorylated S6, phosphorylated S6K, phosphorylated mTOR. phosphorylated Mek, and phosphorylated down-stream proteins thereof. [00119] Embodiments of the invention are summarized as follows:

[00120] The present invention is directed to a method of treating, preventing or ameliorating tumors or symptoms resulting from neurofibromatosis in a subject comprising administering to said subject with neurofibromatosis type 2 (NF2) or a condition associated with the loss of NF2 function or with neurofibromatosis type 1 (NFl) or a condition associated with the loss of NFl function a therapeutically effective amount of at least one composition comprising at least one heat shock protein 90 (HSP90) inhibitor which inhibits or slows growth of one or more NF2-deficient tumors or NFl -deficient tumors, reduces the number of said tumors or inhibits and/or reduces associated symptoms as compared to no treatment with the composition as a control level to determine treatment utility. The method is particularly directed to the administration of the at least one composition comprising HSP90 resulting in a decrease in size and/or number of one or more NF2-deficient tumors or of one or more NFl- defϊcient tumors.

[00121] The method of the present invention comprises administering a HSP90 inhibitor comprising a compound which inhibits or reduces the function of HSP90 complex. More specifically, the HSP90 inhibitor comprises a compound that binds and inhibits the HSP90 protein, modifies HSP90 protein posttranslationally, and/or increases HSP70 or other HSP proteins from their normal levels in the NF2-deficient or NFl -deficient tumors. The administration of the HSP90 inhibitor results in the upregulation or increase in HSP70 in said subject. Further, the method comprises administering a HSP90 inhibitor comprising a compound that degrades or reduces one or more client proteins of HSP90 and the phosphorylated forms of the client proteins. Additionally, the method comprises administering a HSP90 inhibitor comprises a compound that inhibits or reduces activity or phosphorylation of signaling pathway proteins associated with one or more client proteins of HSP90. The one or more client proteins are selected from the group consisting of ErbB2, AKT, and Raf The HSP90 inhibitor inhibits or reduces activity or phosphorylation of the signaling pathways proteins, such as PBK, mTOR, GSK3, 4E-BP1 , Bad, FKHR, HSP90, S6K, S6, Mek, and Erkl/2.

[00122] In a further embodiment, the method comprises administering a HSP90 inhibitor comprising a biological agent or molecule that is a peptide, antibody, siRNA and antisense nucleic acid molecule.

[00123] In still a further embodiment, the method comprises administering at least one composition comprising at least one heat shock protein 90 (HSP90) inhibitor comprising radicicol or a derivative thereof, 17-AAG or a derivative thereof, a purine scaffold-based HSP90 inhibitor or a derivative thereof, a pyrazole scaffold-based HSP90 inhibitor or a derivative thereof, an imidazole scaffold-based HSP90 inhibitor or a derivative thereof, a tetrahydroindolone- or tetrahydroindazolone-based HSP90 inhibitor or a derivative thereof, Novobiocin or a derivative thereof, or any combination thereof. Further, in a further embodiment, the HSP90 inhibitor comprises a HSP90 modulator compound such as a HDAC inhibitor and specifically HDAC6 inhibitor. This HSP90 modulator compound may further comprise Trichostatin A, SAHA, LAQ824, FK228, or derivatives thereof. Further, the method comprises administering a HSP90 inhibitor comprising an inhibitor or compound that modulates or increases the level of HSPs such as HSP70 and HSP27. The HSP90 inhibitor further comprises NZ28 (NCS-134754) or a derivative thereof.

[00124] The method comprises administering the HSP90 inhibitor orally, intravenously or locally, such as intralesionally or topically. The method also encompasses administering the HSP90 inhibitor before, during or after surgical removal of a tumor, Another mode of administration allows the HSP90 inhibitor to be co-administered before, during or after radiation therapy or with a PAK inhibitor or a cytotoxic compound. [00125] The method of the present invention treats, prevents or ameliorates tumors or symptoms resulting from neurofibromatosis type 2 (NF2) or condition(s) associated with the loss of NF2 function. More specifically the one or more NF2-deficient tumors comprise vestibular schwannomas, and more specifically comprise a unilateral vestibular schwannoma or a bilateral vestibular schwannoma. Additionally, the one or more NF2-deficient tumors that are treated comprise spinal cord schwannomas, sporadic schwannomas, peripheral nerve schwannomas, schwannoma, meningioma, mesothelioma, ependymoma, glioma and astrocytoma.

[00126] The method comprises the administration of the HSP90 inhibitor to obtain results in an improvement in at least one of the subject^'s hearing, balance and vision; increase in muscle mass, reduction in tumor burden in the subject, which the latter is identified using a MRI or a CAT scan.

[00127] The method of the present invention treats, prevents or ameliorates tumors or symptoms resulting from neurofibromatosis type 1 (NFl) or condition(s) associated with the loss of NFl function. More specifically the one or more NFl -deficient tumors comprise a dermal and plexiform neurofibromas, optic pathway astrocytomas, optic neuromas, optic gliomas, cerebral astrocytomas, cerebral gliomas, ependymomas, pheochromocytomas and ganglioneuromas, rhabdomyosarcomas, neurofibrosarcomas, malignant peripheral nerve sheath tumors ("MPNST^"), malignant schwannomas, and JMML.

[00128] The present invention also includes a method of inhibiting or reducing the growth or number of NF2-deficient tumor cells or NFl -deficient tumor cells comprising contacting said NF2-deficient tumor cells or NFl -deficient tumor cells with at least one composition comprising at least one heat shock protein 90 (HSP90) inhibitor which inhibits or slows growth and/or reduces the number of one or more NF2-deficient tumors or NFl -deficient tumors. This method comprises contacting said NF2-deficient tumor cells or NFl -deficient tumor cells with said compound occurs in vitro or ex vivo. The NF2-deficient tumor cells are Nf2-deficient mouse Schwann cells and said NFl -deficient tumor cells are NfI -deficient mouse Schwann cells. Or the NF2-deficient tumor cells are NF2-deficient human schwannoma cells and said NFl -deficient tumor cells are NFl -deficient human Schwann cells. The NF2-deficient tumor cells are selected from the group consisting of NF2-deficient schwannoma cell line cells, NF2-deficient meningioma cell line cells and NF2-deficient mesothelioma cell line cells. The NF2-deficient tumor cells are selected from the group consisting of HEI 193 cells, SF1335 cells, BAR cells and RAV cells. The NFl -deficient tumor cells are selected from the group consisting of human MPNST cells, primary neurofibroma cells derived from NFl patients, mouse NfI ;p53-defιcϊent MPNST cell lines established from cisNfl ;p53 mice, and NfI-/- mouse cells, such as Schwann cells, mouse embryonic cells, and leukemia cells. More specifically, the NFl -deficient tumor cells are selected from the group consisting of ST88-14, 88-3, 90-8, and sNF96.2. The NF2-deficient tumor cells or NFl -deficient tumor cells that are contacted with said HSP90 inhibitor can occur in vivo. The NF2-deficient tumor cells or said NFl -deficient tumor cells are from a human, canine, rat or mouse.

[00129] The method of the present invention comprises contacting the NF2-deficient tumor cells or the NFl -deficient tumor cells with a HSP90 inhibitor that results in an inhibition of HSP90 function. The method further comprises contacting the NF2-deficient tumor cells or said NFl -deficient tumor cells with said HSP90 inhibitor that results in an upregulation of HSP70. Further the contact of the NF2-deficient tumor cells or the NFl -deficient tumor cells with the HSP90 inhibitor results in degradation of ErbB2 and/or phosphorylated ErbB2, in degradation of Akt and/or phosphorylated Akt or in degradation of Raf and/or phosphorylated Raf. More specifically, the contact of the NF2-deficient tumor cells or said NFl -deficient tumor cells with the HSP90 inhibitor results in a reduction in phosphorylation of proteins downstream of the ErbB2, Akt or Raf signaling pathway. The degradation or upregulation of the proteins or reduction in phosphorylated proteins is detected using an antibody. [00130] The method also contacts a HSP90 inhibitor with the NFl -deficient and NF2- deficient cells where the HSP90 inhibitor comprises a biological agent or molecule, wherein the biological agent or molecule is selected from the group consisting of peptide, antibody, siRNA and antisense nucleic acid. [00131] In still a further embodiment, the method comprises contacting the NF2-deficent tumor and NFl -deficient tumors with at least one composition comprising at least one heat shock protein 90 (HSP90) inhibitor comprising radicicol or a derivative thereof, 17-AAG or a derivative thereof, a purine scaffold-based HSP90 inhibitor or a derivative thereof, a pyrazole scaffold-based HSP90 inhibitor or a derivative thereof, an imidazole scaffold-based HSP90 inhibitor or a derivative thereof, a tetrahydroindolone- or tetrahydroindazolone-based HSP90 inhibitor or a derivative thereof, Novobiocin or a derivative thereof, or any combination thereof. Further, in a further embodiment, the HSP90 inhibitor comprises a HSP90 modulator compound such as a HDAC inhibitor and specifically HDAC6 inhibitor. This HSP90 modulator compound may further comprise Trichostatin A, SAHA, LAQ824, FK228, or derivatives thereof. Further, the method comprises administering a HSP90 inhibitor comprising an inhibitor or compound that modulates or increases the level of HSPs such as HSP70 and HSP27. The HSP90 inhibitor further comprises NZ28 (NCS-134754) or a derivative thereof. The HSP90 inhibitor also comprises an inhibitor or compound that modulates (e.g. increases) the level of HSPs such as HSP70 and HSP27. The HSP90 inhibitor may also comprise NZ28 (NCS-134754) or a derivative thereof. The method also comprises contacting the NF-2-deficient cells or NF-I -deficient cells are contacted with said compound and a compound that inhibits or reduces PAK activity.

[00132] In another embodiment, the present invention includes a method for screening a test compound for treatment of NF-2 or NF-I comprising treating or contacting NF-2-deficient cells or NF-I -deficient cells with said test compound, wherein a degradation of one or more client proteins of HSP90 or a decrease in activity of signaling pathways associated with one or more client proteins of HSP90 or an increase in HSP70 is indicative of an efficacious treatment of NF-2 or NF- 1. The method further comprises assessing inhibition of HSP90 function. The inhibition of HSP90 function results in an upregulation of HSP70. The one or more client proteins of HSP90 are selected from the group consisting of ErbB2, AKT, and Raf. Additionally, the signaling pathways are associated with one or more client proteins of HSP90 are ErbB2 pathway, AKT pathway or Raf pathway which contain at least one protein selected from group consisting of ErbB2, AKT, Raf, mTOR, GSK3, 4E-BP1 , Bad, FKHR, S6K, S6, Mek, and Erkl/2. Specifically, the one or more client proteins is AKT, the AKT is degraded by said test compound, resulting in reduced phosphorylation of AKT. The treatment results in reduced phosphorylation of S6, GSK3. FKHR, Mek, or Erkl/2. The reduced phosphorylation is detected using an antibody. [00133] The method of the present invention further comprises measuring NF-2-deficient cells or NF-I -deficient cells following treatment with the test compound, wherein a decrease in the number of NF2-deficient cells or NF-I -deficient cells following treatment with the test compound or a decrease in proliferation of NF2-deficient cells or NF-I -deficient cells following treatment with the test compound is indicative of an efficacious treatment. Additionally, the method further comprises comparing the NF2-deficient cells or NF-I - defϊcient cells following treatment to untreated NF2 deficient cells or NF-I -deficient cells, wherein a decrease in one or more client proteins of the HSP90 following treatment with the test compound compared to untreated NF2-deficient cells or NF-I -deficient cells is indicative of an efficacious treatment. Additionally, the method further comprising comparing the NF2-deficient cells or NF-I -deficient cells following treatment to untreated NF2 deficient cells or NF-I -deficient cells, wherein a decrease in number of NF2 deficient cells or NF-I- deficient cells following treatment with the test compound or a decrease in proliferation of NF2-deficient cells or NF-I -deficient cells following treatment with the test compound compared to untreated NF2-deficient cells or NF-I -deficient cells is indicative of an efficacious treatment. The treatment of the NF2 -deficient cells or NFl -deficient cells with said test compound occurs in vitro or ex vivo. The NF2-deficient tumor cells are Nf2- deficient mouse Schwann cells and the NFl -deficient tumor cells are NfI -deficient mouse Schwann cells. Also the NF2-deficient tumor cells are NF2-deficient human schwannoma cells and said NFl -deficient tumor cells are NFl -deficient human Schwann cells. [00134] The NF2-deficient tumor cells are selected from the group consisting of NF2- deficient schwannoma cell line cells, NF2-deficient meningioma cell line cells and NF2- deficient mesothelioma cell line cells. The NF2-deficient tumor cells are selected from the group consisting of HE1193 cells, SF1335 cells, BAR cells and RAV cells. The NFl-deficient tumor cells are selected from the group consisting of human MPNST cells, primary neurofibroma cells derived from NFl patients, mouse N/7;/?5J-deficient MPNST cell lines established from cisNfl ;p53 mice, and NfI-/- mouse cells, such as Schwann cells, mouse embryonic cells, and leukemia cells. More specifically, the NFl-deficient tumor cells are selected from the group consisting of ST88-14, 88-3, 90-8, and sNF96.2. The NF2-deficient tumor cells or NFl-deficient tumor cells that are contacted with said F1SP90 inhibitor can occur in vivo. The NF2-deficient tumor cells or said NFl-deficient tumor cells are from a human, canine, rat or mouse. Examples

[00135] The present invention includes assaying test compounds for use as therapeutics for NF2 of NFl . NF2 deficient or NFl -deficient cells lines as well as NF2-deficient cells or NFl-deficient cells obtained from a patient with NF2 or NFl , respectively, are treated with varying amounts of a test compound, and the effects of the test compound on degradation of one or more client proteins of HSP90, on HSP70 upregulation, and on activity or phosphorylation status of proteins in pathways associated with one or more client proteins of HSP90 can be measured. Compounds that result in a decrease in the amount and/or activity, e.g. decrease or increase in phosphorylation, of one or more client proteins of HSP90, an upregulation of HSP70, or a decrease in activity, e.g. decrease or increase in phosphorylation, of proteins in pathways associated with one or more client proteins of HSP90 can be identified as a putative therapeutic for NF2 or NFl .

[00136] The client proteins of HSP90 (e.g. ErbB2, Akt, Raf, and etc) are involved in many signaling pathways that control diverse functions like translation and cell growth, differentiation, and apoptosis. In order to determine proteins degraded and downstream pathways blocked by a HSP90 inhibitor in N/2-/- Schwann cells or NfI-/- Schwann cells, one or more client proteins and downstream proteins such as Akt, mTOR, S6K, S6, GSK3, Mek, Erkl/2 can be monitored. For example, the effect of a HSP90 inhibitor on Akt is assessed by comparing the amounts of Akt, phospho-Akt, and several phosphorylated downstream proteins (e.g. phospho-S6K, phospho-S6, and phospho-GSK3) in cells treated with the compound and those treated with vehicle (control).

[00137] Cells that are useful for treatment include, but are not limited to, NF2-defϊcient Schwann cells (e.g. HEI- 193), NF2-deficient malignant mesothelioma cells (e.g. BAR and RAV) and NF2-deficient meningioma cells (e.g. SFl 335). For instance, HSP90 inhibitors can be evaluated in a panel of NF2 mutant human and mouse cells and cell lines. Antibodies to one or more client proteins (e.g. Erb2, Akt, or Raf) of HSP90 and activation-specific phospho-antibodies against these proteins or downstream proteins are ideal tools for this purpose (Cell Signaling Technology). Cells in 6 cm dishes are treated with increasing concentrations of compounds (usually 6-8 concentrations guided by the proliferation IC50 for the same cells) for different lengths of time and normalized cell lysates probed in Western blots using antibodies against these proteins and phospho-specific antibodies recognizing only the phosphorylated species.

[00138] Cells that are useful for treatment include, but are not limited to, NFl -deficient human MPNST cells (e.g. ST88-14, 88-3, 90-8, and sNF96.2) (Basu et al., 1992, Nature 356: 713-715; DeClue et al., 1992, Cell 69: 265-273; Wallace et al., 2000, Genes Chromosomes Cancer 27(2):1 17-123; Muir et al., 2001, Am. J. Pathol. 158: 501-513), primary neurofibroma cells derived from NFl patients, mouse Λ//7;/?53-deficient MPNST cell lines established from cisNfl;p53 mice (Vogel et al., 1999, Science 286: 2176-2179), and NfJ-/- mouse cells (e.g. Schwann cells, mouse embryonic cells, and leukemia cells).

L 17 -AAG, α HSP90 inhibitor, causes degradation ofAkt in NF2 deficient mouse and human tumor cells

[00139] It has been shown that inhibition of HSP90 function in breast cancer cells causes down-regulation of Akt (Basso et al., 2002, J. Biol. Chem. 277(42): 39858-39866) . The inventors have determined that phospho-Akt levels are elevated in N/2-/- mouse Schwann cells, NF2 defϊent human schwannomas, NF2 deficient meningioma xenografts, NF2 deficient mesothelioma xenografts as compared to wild-type mouse Schwann cells and/or normal human peripheral nerves (reference is made to a PCT application entitled "Treatment of Neurofibromatosis with Inhibitors of a Signal Transduction Pathway" referenced as Attorney Docket No. NEXG-005-01 WO, filed on June 4, 2007, and is incorporated in its entirety by reference). To assess the effect of HSP90 inhibitors on Akt and phospho-Akt in NF2 deficient cells, Western blots were prepared from various NF2-deficient cells, including Nf2-/- mouse Schwann cells, NF2 deficient schwannoma cells, NF 2 deficient meningioma cells, and NF2 deficient mesothelioma cells. The blot was prepared using methods known in the art. The cells were treated with 0.5 μM 17-AAG for 6, 12, or 24 hours. As control the same cells were treated with vehicle DMSO for 24 hours. The results show that treatment of NF2 deficient cells with 17-AAG, a known potent HSP90 inhibitor, caused a decline of both phospho- and total Akt levels (Figure 1 ). The loss of Akt was time-dependent. The more rapid decline of Akt phosphorylation might partially be caused by the degradation of ErbB2 upon 17-AAG treatment (see Figure 2A). ErbB2, one of the well-documented client proteins of HSP90, lies upstream of the AKT pathway in Schwann cells. Taken together, these data suggest that pharmacological inhibition of HSP90 function blocks the deregulated Akt pathway in NF2 mutant cells.

2. 17-AAG causes degradation ofErbB2 and Rafin NF2 deficient mouse and human tumor cells

[00140] To assess the effect of HSP90 inhibitors on ErbB2 and Raf in NF2 deficient cells, Western blots were prepared from various NF2-deficient cells, including Nf2-/- mouse Schwann cells, NF2 deficient schwannoma cells, NF2 deficient meningioma cells, and NF2 deficient mesothelioma cells. The blot was prepared using methods known in the art. The cells were treated with 0.5μM 17-AAG for 6, 12, or 24 hours or treated with 0.02μM, 0.1 μM, 0.5μM 17-AAG or radicicol for 24 hours. As control the same cells were treated with vehicle DMSO for 24 hours. The inventors of the present invention determined that treatment of NF2 deficient cells with 17-AAG, the known potent HSP90 inhibitor, caused a decline of both ErbB2 and Raf levels (Figure 2 A and 2B), except in Λ^/F2-deficient mesothelioma cells (RAV) in which there is no ErB2 expression. The loss of ErbB2 and Raf proteins were both time- and dose-dependent. Similarly, radicicol, another known potent HSP90 inhibitor, caused a decline of both ErbB2 and Raf levels in NJ2-/- mouse Schwann cells in a dose- dependent manner (Figure 2B).

[00141} Similar methods are used to assess the effect of HSP90 inhibitors on ErbB2 and Raf in NFl-deficient cells such as NFl-deficient MPNST cells, NfI-/- mouse Schwann cells, and mouse 7y/7;/?53-deficient MPNST cells. In these cells, Schwann cell mitogen neuregulins signal though ErbB2 to exert their effects on cell proliferation and survival. Ras-Raf-Mek- Erkl/2 pathway is activated in the NFl-deficient cells. Degradation of ErbB2 and Raf induced by HSP90 inhibitors may have effects on the proliferation and survival of these cells.

3. 17-AAG causes upregulation ofHSPK) in NF2 deficient mouse and human tumor cells [00142] To assess the effect of HSP90 inhibitors on HSP70 in NF2 deficient cells, Western blots were prepared from various NF2-deficient cells, including N/2-/- mouse Schwann cells, NF2 deficient schwannoma cells, NF2 deficient meningioma cells, and NF2 deficient mesothelioma cells. The blot was prepared using methods known in the art. The cells were treated with 0.5μM 17-AAG for 6, 12, or 24 hours or treated with 0.02μM, 0.1 μM, 0.5μM

17-AAG or radicicol for 24 hours. As control the same cells were treated with vehicle DMSO for 24 hours. The inventors of the present invention found that treatment of NF2 deficient cells with 17-AAG, the known potent HSP90 inhibitor, caused an upregulation of HSP70 (Figure 2A and 2B). The increase of HSP70 protein level was both time- and dose-dependent. Similarly, radicicol, another known potent HSP90 inhibitor, caused an upregulation of HSP70 in N/2-/- mouse Schwann cells in a dose-dependent manner (Figure 2B). Similarly, HSP70 upregulation induced by HSP90 inihibitors can be verified in NF 1 -deficient cells.

4. Proliferation Assay

[00143] Inhibitors of HSP90 function is assayed for the ability to decrease the number of NF2 deficient tumor cells in a tumor, i.e., shrink a tumor, or reduce the proliferation of NF2 deficient tumor cells. Inhibitors that are useful to assay, include, but are not limited to, HSP90 inhibitors such as 17-AAG, 17-DMAG, other geldanamycin derivatives, radicicol, radicicol derivatives, purine-based HSP90 inhibitors, pyrazole- or imidazole- based HSP90 inhibitors; tetrahydroindolone- or tetrahydroindazolone-based inhibitors; and HSP90 modulators that modulate the activity of the HSP90 protein or complex via post-translational modifications such as acetylation or deaceylation. For instance, HDAC inhibitors, such as SAHA, Trichostatin A (TSA), FK228, or HDAC6 inhibitor are known to modulate HSP90. [00144] The ability of inhibitors to decrease the number of NF2 deficient tumor cells in a sample or reduce proliferation of NF2 deficient tumor cells is assessed using a variety of methods known in the art. For instance, compounds are assessed using a proliferation assay using paired N/2-/- and N/2+/+ Schwann cells or paired NfI-/- and NfI+/+ Schwann cells. A pre-determined number of cells (to reach -70% confluence in 4 days) are plated and cultured in 96-well plates along with various concentration of compounds for 4 days. A positive control compound and a vehicle (usually DMSO) control are included with each assay. The number of viable cells is measured using ATPlite assay (Perkin Elmer) as described in the manufacture's manual. Various growth conditions such as steady state and reduced growth factor conditions are tested as well. 1C50, the concentration needed for 50% inhibition of cell proliferation, are determined and analyzed for each compound. Efficacious compounds should have about an IC50 < lOμM.

[00145] Inhibition activity of HSP90 inhibitors on cell proliferation of NF2-deficient cells is shown in Figure 3. The chart shows inhibition activity of 17-AAG, Radicicol, and 17- DMAG on cell proliferation of NfI-/- mouse Schwann cells. IC50s were calculated using XLfit 4.1 software and listed below the chart along with their IC50s on cell proliferation of HE1193 human schwanoma, SF1335 human meningioma, and BAR human mesothelioma cell lines.

[00146] Inhibition activity of HDAC inhibitor TSA on cell proliferation of NF2-deficient cells is shown in Figure 4. IC50s of TSA on NfI-I- SC, SF 1335 human meningioma, HEI 193 human schwanoma, and BAR human mesothelioma cell lines are 0.02μM, 0.02μM, 0.04μM, and 0.05μM, respectively. To provide further evidence that the inhibition of TSA on the proliferation of the NF2-deficient cells is due to its ability to modulate HSP90 funciton, degradation of Akt, ErbB2, and Raf upon TSA treatment are monitored. Kovacs et al. (2005, Molecular Cell, 18: 601-607) reported that HDAC6 is responsible for modulation of HSP90 function.

[00147] Similar ATPlite assay can be used to determine IC50s of various HSP90 inhibitors on proliferation of NFl -deficient human MPNST cells (e.g. ST88-14, 88-3, 90-8, and sNF96.2), primary neurofibroma cells derived from NFl patients, mouse 7V/7/p53-deficient MPNST cells and other NfI -deficient mouse cells.

5. Restoration of contact inhibition

[00148] Nf2-/- mouse cells escape the control of contact-inhibition and therefore they are able to grow to a higher density as compared to the wild-type cells (Lallemand et al., 2003, Genes Dev. 17(9): 1090-1 100). N/2-/- rat schwannoma cells form foci after growing at high density, which could be reversed by reintroduction of wild-type Merlin into the cells (Morrison et al., 2001, Genes Dev. 15(8): 968-980). For this reason, compounds that cause cells to exhibit contact-inhibition to a greater degree than NF2 deficient cells can be considered to be efficacious for the treatment of NF2.

[00149] Briefly, N/2-/- mouse Schwann cells were seeded at low cell density and cultured in 6-well plates for 2-3 days to reach confluency and then various concentrations of 17-AAG were added. Vehicle treated Nf2-/- Schwann cells continued proliferating and formed foci- like structures 24-48 hrs after reaching confluency. Np-/- Schwann cells treated with 17- AAG stopped proliferating and did not form any foci-like structures. As shown in Figure 5, 17-AAG restored the contact inhibition of N/2-/- Schwann cells in a dose-dependent manner.

6. Xenografts, Animal models, and Treatment

[00150] The ability of a test compound to act as a therapeutic in NF2 or NFl by modulating the HSP90 complex is also assessed using animal xenograft experiments. Xenograft experiments were performed with subcutaneous tumor formation in nude mice or SCID mice using a human NF2 '-deficient malignant mesothelioma cell line RAV, a benign meningioma cell line or Np^''^' SCs. A dermal neurofibroma (DNF) xenograft model has been established to evaluate compounds useful for treating NFl neurofibromas (PCT publication WO 06/083979). In particular, these experiments have allowed the inventors of the invention to define the treatment starting point for each xenograft model.

[00151] In order to assess the action of a test compound in xenograftic mice, mice are randomized among control and treated groups with 8-12 mice in each experimental group. For oral dosing, compound are suspended in 0.5% (w/v) methyl cellulose or other suitable dosing vehicles known in the art. Dosing starts from a predefined starting point for each cell system (i.e. 100-200 mm^J at 3-5 days for Np-/- Schwann cells). Mice are dosed once or twice a day with high, medium, low doses and vehicle control for 4 weeks or less determined by preset tumor volume criteria. The actual dose should be calculated based on data of in vitro analyses, literature precedent, and maximal tolerated dose (MTD) determined using normal mice. In some cases, it may be optimal to dose via intravenous, intraperitoneal or intralesional routes. In case of significant variations in body weight during the treatment period, doses can be adjusted accordingly.

[00152] Mice are monitored daily and tumor growth, assessed based on tumor volume (V= [length x width ] π/6), and measured twice a week with calipers. Tumor formation is monitored for the duration of the treatment or longer, for instance, 3-6 weeks. Animals are sacrificed earlier when they meet predetermined criteria established for minimizing pain and suffering. Treatment efficacy endpoints are assessed in terms of the compound's effects on tumor growth of treated mice relative to that of control vehicle-treated mice. Two evaluation criteria are used in parallel: (/) Growth Inhibition, calculated as the ratio of the mean tumor volume of drug-treated versus control groups: T/C percent = (mean tumor volume of compound-treated group on day X / mean tumor volume of control group on day X) x 100, the optimal value, being the minimal T/C ratio which reflects the maximal tumor growth inhibition achieved and (U) Specific Tumor Growth Delay (SGD), calculated as [Td (compound-treated group)-Td (vehicle-treated group)] / Td (vehicle-treated group), with Td being the tumor doubling time of compound-treated and control groups, defined as the time in days required for the tumor volume to double.

[00153] An example of a xenograft experiment to test the effect of 17-DMAG, a HSP90 inhibitor, on the growth of N/2-/- Schwann cell tumor in nude mice is described below. Five week old Swiss nu/nu mice were implanted with 10^ή N/2-/- Schwann cells (SC4 cells, a clone of Nf2-/- Schwann cells). When the tumors reached the size of ~100 mm , mice were randomized to receive vehicle (water), 20 mg/kg 17-DMAG once daily (IX group), or 10 mg/kg 17-DMAG twice daily (2X group) by oral gavage for 5 days per week. The treatment cycle repeated for four weeks. The day of randomization was designated as Day 0 which is also the first day of dosing. The tumor volume was determined by two-dimensional measurement with a caliper on the day of randomization (DayO) and then once/week. Tumor volumes were calculated according to the formula (a x b2) x 0.5, where a represents the largest and b the perpendicular tumor diameter. Antitumor activity was evaluated as maximum tumor volume inhibition versus the vehicle control group. Data evaluation was performed using specifically designed software (Prism, GraphPad software). 17-DMAG significantly (p=0.031) slowed the progression of the SC4 cell line xenograft (Figure 6). Tumor doubling times were 6 days for the control group, 7.5 days for the IX group and 8 days for the 2X group. The optimal T/C value of 65% was observed on the last day of the experiment (Day30) for group 2X and 69% on day 18 for group IX. Significant average tumor weight reduction was observed at day30 in the treated groups: -31 % and -38% of the control group for group IX and 2X, respectively (Figure 6).

[00154] Various HSP90 inhibitors are tested in cisNfl;p53 mouse models developed previously (Vogel et al., 1999, Science 286: 2176-2179; Cichowski et al., 1999 Science. 286: 2172-2176). MPNSTs can harbor mutations in at least 2 tumor suppressor genes in addition to the NFl loss of heterozygosity. In particular, several studies have reported mutations in the p53 gene. The Nfl;p53 mice develop tumors with a 100% incidence between 5 and 6 months of age. In all cases the tumors exhibit characteristics of NFl associated malignancies of the peripheral nervous system, including MPNSTs, triton tumors and rhabdomyosarcomas, according to histopathological criteria. The full penetrance and reproducibility of tumor timing of appearance make the cisNfl ;p53 mouse ideal for testing therapeutic compounds since reduction in tumor burden or delay in tumor appearance can be readily monitored. [00155] Mice are randomized among control and treated groups with 15-20 mice in each experimental group. Dosing starts from a predefined starting point (i.e. ~200 mm ). Mice are dosed every week day with high, medium, and low doses and vehicle control for 8 weeks or less beginning at 18-20 weeks of age, when 30-50% of mice begin to develop tumors. The high dose is defined as the MTD dose of the test compound with similar schedule. If toxicity is an issue for the proposed duration, lower starting dose or increase the sample size per group are implemented so that a sufficient number of live mice are evaluated at the end of the study. Test agents are administered via intraperitoneal (i.p.), intravenous (i.v.), or oral route. In case of significant variations in body weight during the treatment period, doses are adjusted accordingly or experiments can be repeated with the adjusted doses. [00156] Typically, cisNfl;p53 mice that develop tumors become less active and assume classic rounded positions and ruffled coat. An untreated cohort of mice is expected to begin to develop signs of ill health within the fifth month of age. Pairs of control and test mice are sacrificed on a weekly basis once the signs of illness become apparent in control mice. All mice are carefully necropsied and the number, location and size of all tumors are noted. All tumor samples are evaluated for histologic and immunohistochemical analysis to deteπnine pathology as well as evidence for apoptosis, necrosis, and proliferation. [00157] For compound efficacy analysis, the mean tumor volume of each dosing group are compared to that of the vehicle control group. Student's t-test is used for statistical analysis of tumor volume. Differences with a p-value <0.05 is considered as statistically significant. 7. Pharmacodynamic Assays Measuring In Vivo Target Inhibition [00158] Various pharmacodynamic (PD) assays are useful to measure in vivo target inhibition.

[00159] The present invention also includes screening for degradation of one or more client proteins of HSP90 or upregulation of HSP70 using peripheral blood mononuclear cells ("PMBC PD assay"). In this assay, whole blood from groups of about 5 similarly treated normal and/or mice harboring NF2-deficient or NFl -deficient tumors at efficacious doses is collected and pooled in a single heparinized Vacutainer tube (BD biosciences, NJ), and peripheral blood mononuclear cells (PBMCs) are isolated as reported (Graff et al., 2005, Cancer Res. 65(16): 7462-7469; Peralba et al., 2003, Clin. Cancer Res. 9(8): 2887-2892). PBMCs are collected at 0, 2, 4, 8, and 24 hours post dosing. PBMCs are lysed directly for Western blots or for immunoprecipitation first and then Western blots to detect target proteins. For example, HSP70 upregulation by a HSP90 inhibitor is detected in PBMCs (Ramanathan et al., 2007, Clin. Cancer Res. 13(6): 1769-1774).

[00160] In yet another assay ("tumor tissue PD assay^"'), either target protein degradation, phosphorylation, and HSP70 upregulation in tumor lysates by Western blots or in tumor sections (i.e. paraffin-embedded sections) by immunohistochemistry are used to assay the effects of the test compound on target proteins. Tumor tissues are harvested at the same time points as described above for PBMCs. Each tumor sample is divided in two pieces with one flash frozen in liquid nitrogen immediately and the other fixed in 10% buffered formalin and then paraffin-embedded. ErbB2, phospho-Akt, and phospho-S6 levels in N/2 -/-Schwann cell xenografts have been shown to be very high and can be readily detected by immunohistochemistry (reference is made to a PCT application entitled "Treatment of Neurofibromatosis with Inhibitors of a Signal Transduction Pathway^" referenced as Attorney Docket No. NEXG-005-01 WO, filed on June 4, 2007). Phospho-S6 level in NfI-/- tumor cells is also elevated and is readily detected by immunohistochemistry (Johannessen et al., Proc. Natl. Acad. ScL U.S.A. 2005, 102(24):8573-8578; Dasgupta et al., Cancer Res. 2005, 65(7):2755-2760).

[00161] Examples of degradation of client proteins (e.g. ErbB2, Raf, Akt) and upregulation of HSP70 in N/2-/- Schwann cell tumors of untreated and 17-DMAG treated animals are shown in Figure 7. In the 17-DMAG treated group, Raf relative protein level decreased starting from 6h and 23h after treatment, while HSP70 protein level increased. [00162] It is understood that the present invention is not limited to the particular methods and components, etc, described herein, as these may vary. It is also to be understood that the terminology used herein is used for the purpose of describing particular embodiments only, and is not intended to limit the scope of the present invention. It must be noted that as used herein, the singular forms "a," "an," and "the" include the plural reference unless the context clearly dictates otherwise.

[00163] Although the present invention has been described in detail with reference to examples above, it is understood that various modifications can be made without departing from the spirit of the invention. All cited patents, patent applications and publications referred to in this application are herein incorporated by reference in their entirety.

Claims

We Claim:

1. A method of treating, preventing or ameliorating tumors or symptoms resulting from neurofibromatosis in a subject comprising administering to said subject with neurofibromatosis type 2 (NF2) or a condition associated with the loss of NF2 function or with neurofibromatosis type 1 (NFl) or a condition associated with the loss of NFl function a therapeutically effective amount of at least one composition comprising at least one heat shock protein 90 (HSP90) inhibitor which inhibits or slows growth of one or more NF2- deficient tumors or NFl -deficient tumors, reduces the number of said tumors or inhibits and/or reduces associated symptoms as compared to no treatment with said composition.

2. The method of claim 1 , wherein administration of the at least one composition results in a decrease in size and/or number of said one or more NF2-deficient tumors.

3. The method of claim 1 , wherein administration of the at least one composition results in a decrease in size and/or number of said one or more NFl -deficient tumors.

4. The method of any one of claims 1-3, wherein said HSP90 inhibitor comprises a compound which inhibits or reduces the function of HSP90 complex.

5. The method of claim 4, wherein said HSP90 inhibitor comprises a compound that binds and inhibits the HSP90 protein, modifies HSP90 protein posttranslationally, and/or increases HSP70 or other HSP proteins from their normal levels in the NF2-deficient or NFl -deficient tumors.

6. The method of claim 4, wherein said HSP90 inhibitor comprises a compound that degrades or reduces one or more client proteins of HSP90 and the phosphorylated forms of said client proteins.

7. The method of claim 4, wherein said HSP90 inhibitor comprises a compound that inhibits or reduces activity or phosphorylation of signaling pathway proteins associated with one or more client proteins of HSP90.

8. The method of claim 6, wherein said one or more client proteins are selected from the group consisting of ErbB2, AKT, and Raf.

9. The method of claim 6, wherein said HSP90 inhibitor inhibits or reduces phosphorylation of ErbB2, AKT, and Raf.

10. The method of claim 7, wherein said signaling pathways proteins are selected from the group consisting of PBK, mTOR, GSK3, 4E-BP1, Bad, FKHR, HSP90, S6K, S6, Mek, and Erkl/2.

1 1. The method of any one of claims 1 -3, wherein said HSP90 inhibitor comprises radicicol or a derivative thereof.

12. The method of any one of claims 1-3, wherein said HSP90 inhibitor comprises 17-AAG or a derivative thereof

13. The method of any one of claims 1-3, wherein said HSP90 inhibitor comprises a biological agent or molecule.

14. The method of claim 13, wherein said HSP90 inhibitor comprises an agent or a molecule selected from the group consisting of peptide, antibody, siRNA and antisense nucleic acid molecule.

15. The method of any one of claims 1-3, wherein said HSP90 inhibitor comprises a purine scaffold-based HSP90 inhibitor or a derivative thereof, a pyrazole scaffold-based HSP90 inhibitor or a derivative thereof, an imidazole scaffold-based HSP90 inhibitor or a derivative thereof, a tetrahydroindolone- or tetrahydroindazolone-based HSP90 inhibitor or a derivative thereof, Novobiocin or a derivative thereof, or any combination thereof.

16. The method of any one of claims 1 -3, wherein said HSP90 inhibitor comprises a HSP90 modulator compound such as a HDAC inhibitor and specifically HDAC6 inhibitor.

17. The method of any one of claims 16, wherein said HSP90 modulator compound is selected from the group consisting of Trichostatin A, SAHA, LAQ824, FK228, and a derivative thereof.

18. The method of any one of claims 1-3, wherein said HSP90 inhibitor is an inhibitor or compound that modulates or increases the level of HSPs such as HSP70 and HSP27.

19. The method of any one of claims 1-3, where said HSP90 inhibitor comprises NZ28 (NCS-134754) or a derivative thereof.

20. The method of any one of claims 1-3, wherein said HSP90 inhibitor is administered orally, intravenously or locally, such as intralesionally or topically.

21. The method of any one of claims 1 -3, wherein said HSP90 inhibitor is administered before, during or after surgical removal of a tumor.

22. The method of any one of claims 1-3, wherein said HSP90 inhibitor is co-administered before, during or after radiation therapy.

23. The method of any one of claims 1-3, wherein said HSP90 inhibitor is co-administered with a PAK inhibitor or a cytotoxic compound.

24. The method of any one of claims 1-3, wherein said HSP90 inhibitor results in the upregulation or increase in HSP70 in said subject.

25. The method of 2, wherein the one or more NF2-deficient tumors comprise vestibular schwannomas.

26. The method of claim 25, wherein the one or more NF2-defϊcient tumors comprise a unilateral vestibular schwannoma or a bilateral vestibular schwannoma.

27. The method of claim 2, wherein the one or more NF2-deficient tumors comprise spinal cord schwannomas.

28. The method of claim 2, wherein the one or more NF2-deficient tumors comprise sporadic schwannomas.

29. The method of claim 2, wherein the one or more NF2-deficient tumors comprise peripheral nerve schwannomas.

30. The method of claim 2, wherein the one or more NF2-deficient tumors are selected from the group consisting of schwannoma, meningioma, mesothelioma, ependymoma, glioma and astrocytoma.

31. The method of claim 2, wherein administration of the HSP90 inhibitor results in an improvement in at least one of the subject's hearing, balance and vision.

32. The method of claim 2, wherein administration of the HSP90 inhibitor results in an increase in muscle mass.

33. The method of claim 2, wherein administration of the HSP90 inhibitor compound reduces tumor burden in the subject.

34. The method of claim 33, wherein the reduction in tumor burden is identified using a MRl or a CAT scan.

35. The method of claim 3, wherein one or more NFl-deficient tumors are selected from the group consisting of dermal and plexiform neurofibromas, optic pathway astrocytomas, optic neuromas, optic gliomas, cerebral astrocytomas, cerebral gliomas, ependymomas, pheochromocytomas and ganglioneuromas, rhabdomyosarcomas, neurofibrosarcomas, malignant peripheral nerve sheath tumors ("MPNST^"), malignant schwannomas, and JMML.

36. A method of inhibiting or reducing the growth or number of NF2-deficient tumor cells or NFl -deficient tumor cells comprising contacting said NF2-deficient tumor cells or NFl - deficient tumor cells with at least one composition comprising at least one heat shock protein 90 (HSP90) inhibitor which inhibits or slows growth and/or reduces the number of one or more NF2-deficient tumors or NFl-deficient tumors.

37. The method of claim 36, wherein contacting said NF2-deficient tumor cells or NFl - deficient tumor cells with said compound occurs in vitro or ex vivo.

38. The method of claim 36, wherein said NF2-defϊcient tumor cells are Nf2-deficient mouse Schwann cells and said NFl -deficient tumor cells are NfI -deficient mouse Schwann cells.

39. The method of claim 36, wherein said NF2-deficient tumor cells are NF2-deficient human schwannoma cells and said NFl-deficient tumor cells are NFl-deficient human Schwann cells.

40. The method of claim 36, wherein said NF2-deficient tumor cells are selected from the group consisting of NF2-deficient schwannoma cell line cells, NF2-deficient meningioma cell line cells and NF2-deficient mesothelioma cell line cells.

41. The method of claim 40, wherein said NF2-deficient tumor cells are selected from the group consisting of HEI193 cells, SF1335 cells, BAR cells and RAV cells.

42. The method of claim 36, wherein said NFl-deficient tumor cells are selected from the group consisting of human MPNST cells, primary neurofibroma cells derived from NFl patients, mouse Λ//7;jp53-deficient MPNST cell lines established from cisNfl ;p53 mice, and NfI-/- mouse cells, such as Schwann cells, mouse embryonic cells, and leukemia cells.

43. The method of claim 42, wherein said NFl-deficient tumor cells are selected from the group consisting of ST88-14, 88-3, 90-8, and sNF96.2.

44. The method of claim 37, wherein contacting said NF2-deficient tumor cells or NFl - deficient tumor cells with said HSP90 inhibitor occurs in vivo.

45. The method of claim 37, wherein said NF2-deficient tumor cells or said NFl-deficient tumor cells are from a human, canine, rat or mouse.

46. The method of claim 36, wherein contact of said NF2-deficient tumor cells or said NFl - deficient tumor cells with said HSP90 inhibitor results in an inhibition of HSP90 function.

47. The method of claim 36, wherein contact of said NF2-deficient tumor cells or said NFl- deficient tumor cells with said HSP90 inhibitor results in an upregulation of HSP70.

48. The method of claim 36, wherein contact of said NF2-deficient tumor cells or said NFl- deficient tumor cells with said HSP90 inhibitor results in degradation of ErbB2 and/or phosphorylated ErbB2, in degradation of Akt and/or phosphorylated Akt or in degradation of Raf and/or phosphorylated Raf.

49. The method of claim 48, wherein contact of said NF2-deficient tumor cells or said NFl- deficient tumor cells with said HSP90 inhibitor results in a reduction in phosphorylation of proteins downstream of the ErbB2, Akt or Raf signaling pathway.

50. The method of claims 48 or 49, wherein said degradation or upregulation of the proteins or reduction in phosphorylated proteins is detected using an antibody.

51. The method of claim 36, wherein said HSP90 inhibitor comprises a biological agent or molecule.

52. The method of claim 51, wherein said biological agent or molecule is selected from the group consisting of peptide, antibody, siRNA and antisense nucleic acid.

53. The method of claim 36, wherein said HSP90 inhibitor comprises radicicol or a derivative thereof.

54. The method of claim 36, wherein said HSP90 inhibitor comprises 17-AAG or a derivative thereof.

55. The method of claim 36, wherein said HSP90 inhibitor comprises a purine scaffold-based HSP90 inhibitor or a derivative thereof, a pyrazole scaffold-based HSP90 inhibitor or a derivative thereof, an imidazole scaffold-based HSP90 inhibitor or a derivative thereof, a tetrahydroindolone- or tetrahydroindazolone-based HSP90 inhibitor or a derivative thereof, Novobiocin or a derivative thereof, or any combination thereof.

56. The method of claim 36, wherein said HSP90 inhibitor comprises a HSP90 modulator compound such as a HDAC inhibitor and specifically HDAC6 inhibitor.

57. The method of claim 56, wherein said HSP90 modulator compound is selected from the group consisting of Trichostatin A, SAHA, LAQ824, FK228, and a derivative thereof.

58. The method of claim 36, wherein said HSP90 inhibitor is an inhibitor or compound that modulates (e.g. increases) the level of HSPs such as HSP70 and HSP27.

59. The method of claim 36 where said HSP90 inhibitor comprises NZ28 (NCS-134754) or a derivative thereof.

60. The method of claim 36, wherein said NF-2-deficient cells or NF-I -deficient cells are contacted with said compound and a compound that inhibits or reduces PAK activity.

61. A method for screening a test compound for treatment of NF-2 or NF-I comprising treating or contacting NF-2-deficient cells or NF-I -deficient cells with said test compound, wherein a degradation of one or more client proteins of HSP90 or a decrease in activity of signaling pathways associated with one or more client proteins of HSP90 or an increase in HSP70 is indicative of an efficacious treatment of NF-2 or NF-I .

62. The method of claim 61, further comprising assessing inhibition of HSP90 function.

63. The method of claim 62, wherein said inhibition of HSP90 function results in an upregulation of HSP70.

64. The method of claim 61, wherein said one or more client proteins are selected from the group consisting of ErbB2, AKT, and Raf.

65. The method of claim 61, wherein said signaling pathways associated with one or more client proteins of HSP90 are ErbB2 pathway, AKT pathway or Raf pathway which contain at least one protein selected from group consisting of ErbB2, AKT, Raf, mTOR, GSK3, 4E- BPl , Bad, FKHR, S6K, S6, Mek, and Erkl/2.

66. The method of claim 61 , wherein said one or more client proteins is AKT, said AKT is degraded by said test compound, resulting in reduced phosphorylation of AKT.

67. The method of 61, wherein said treatment results in reduced phosphorylation of S6, GSK3, FKHR, Mek, or Eric 1/2.

68. The method of claims 66 or 67, wherein said reduced phosphorylation is detected using an antibody.

69. The method of claim 61, further comprising measuring NF-2-deficient cells or NF-I- deficient cells following treatment with the test compound, wherein a decrease in the number of NF2-defiicient cells or NF-I -deficient cells following treatment with the test compound or a decrease in proliferation of NF2-defϊcient cells or NF-I -deficient cells following treatment with the test compound is indicative of an efficacious treatment.

70. The method of claim 61 , further comprising comparing the NF2-deficient cells or NF-I - deficient cells following treatment to untreated NF2 deficient cells or NF-I -deficient cells, wherein a decrease in one or more client proteins of the HSP90 following treatment with the test compound compared to untreated NF2-deficient cells or NF-I -deficient cells is indicative of an efficacious treatment.

71. The method of claim 61, further comprising comparing the NF2-deficient cells or NF-I - deficient cells following treatment to untreated NF2 deficient cells or NF-I -deficient cells, wherein a decrease in number of NF2 deficient cells or NF-I -deficient cells following treatment with the test compound or a decrease in proliferation of NF2-deficient cells or NF- 1 -deficient cells following treatment with the test compound compared to untreated NF2- deficient cells or NF-I -deficient cells is indicative of an efficacious treatment.

72. The method of claim 61 , wherein treatment of said NF2-deficient cells or NFl -deficient cells with said test compound occurs in vitro or ex vivo.

73. The method of claim 61 , wherein said NF2-deficient tumor cells are Nf2-deficient mouse Schwann cells and said NFl -deficient tumor cells are NfI -deficient mouse Schwann cells.

74. The method of claim 61. wherein said NF2-deficient tumor cells are NF2-deficient human schwannoma cells and said NFl -deficient tumor cells are NFl -deficient human Schwann cells.

75. The method of claim 61 , wherein said NF2-deficient tumor cells are selected from the group consisting of NF2-defϊcient schwannoma cell line cells, NF2-deficient meningioma cell line cells and NF2-deficient mesothelioma cell line cells.

76. The method of claim 75, wherein said NF2-deficient tumor cells are selected from the group consisting of HEI 193 cells, SFl 335 cells, BAR cells and RAV cells.

77. The method of claim 61, wherein said NFl -deficient tumor cells are selected from the group consisting of human MPNST cells, primary neurofibroma cells derived from NFl patients, mouse /V/7;/?53-deficient MPNST cell lines established from cisNfl;p53 mice, and NfI-/- mouse cells, such as Schwann cells, mouse embryonic cells, and leukemia cells.

78. The method of claim 77, wherein said NFl -deficient tumor cells are selected from the group consisting of ST88-14, 88-3, 90-8, and sNF96.2.

79. The method of claim 61 , wherein contacting said NF2-deficient tumor cells or NFl - deficient tumor cells with said HSP90 inhibitor occurs in vivo.

80. The method of claim 61, wherein said NF2-deficient tumor cells or said NFl -deficient tumor cells are from a human, canine, rat or mouse.