WO2008013987A2

WO2008013987A2 - N-alkyl substituted piperazinylmethylquinazolinones and azepanylmethylquinazolinones

Info

Publication number: WO2008013987A2
Application number: PCT/US2007/016996
Authority: WO
Inventors: Michael Pierce; Longwu Qi; Paul B. Robbins; Sudhir R. Sahasrabudhe; Robert Selliah; Raj Gopal Venkat
Original assignee: Prolexys Pharmaceuticals, Inc.
Priority date: 2006-07-27
Filing date: 2007-07-27
Publication date: 2008-01-31
Also published as: WO2008013987A3

Abstract

Compounds represented by Structural Formula (I) : are useful, for example, in the effective killing or reduction in rate of proliferation of cancer cells, such as in patients suffering from cancer. In addition to the compounds themselves, the invention provides pharmaceutical compositions of the compounds and method of treatment using the compounds.

Description

N-ALKYL SUBSTITUTED PIPERAZINYLMETHYLQUINAZOLINONES AND AZEPANYLMETHYLQUINAZOLINONES

RELATED APPLICATION

This application claims priority to U.S. Provisional Appplication No. 60/834,027, filed on July 27, 2006, the entire contents of which is incorporated herein by reference.

BACKGROUND OF THE INVΕNTION

Many drugs administered to treat a disease are targeted against general differences between a diseased cell and a normal cell. For example, paclitaxel., which is used to treat ovarian and breast cancer and inhibits microtubule function, is thought to exhibit tumor cell specificity based on the greater rate of proliferation of tumor cells relative to normal cells (Miller and Ojima, Chem. Rec. 1 :195-211, 2002). However, despite this consensus view, paclitaxel's in vitro activity varies widely across tumor cell lines (Weinstein et al., Science 275:343-349, 1997), indicating that genetic factors can modify sensitivity of tumor cells to paclitaxel and that the responsiveness of tumor cells is not simply determined by their rate of proliferation.

Molecularly targeted therapeutics represent a promising new approach to anti-cancer drug discovery (Shawver et al, Cancer Cell 1: 117-23, 2002). Using this approach, small molecules are designed to inhibit directly the very oncogenic proteins that are mutated or overexpressed in specific tumor cell types. By targeting specific molecular defects found within tumor cells, this approach may ultimately yield therapies tailored to each tumor's genetic makeup. Two recent examples of successful molecularly targeted anti-cancer therapeutics are Gleevec (imatinib mesylate), an inhibitor of the breakpoint cluster region- abelsen kinase (BCR-ABL) oncoprotein found in Philadelphia chromosome-positive chronic myelogenous leukemia (Capdeville et al., Nat Rev Drug Discov 1 : 493-502, 2002) and Herceptin (trastuzumab), a monoclonal antibody targeted against the HER2/NEU oncoprotein found in metastatic breast cancers (Mokbel and Hassanally, Curr Med Res Opin 17: 51-9_S 2001).

A complementary strategy involves searching for genotype-selective anti-tumor agents that become lethal to tumor cells only in the presence of specific oncoproteins or in the absence of specific tumor suppressors. Such genotype-selective compounds might target oncoproteins directly or they might target other critical proteins involved in oncoprotein- linked signaling networks. Compounds that have been reported to display synthetic lethality include (i) the rapamycin analog CCI-779 in myeloma cells lacking PTEN (Shi et al., Cancer Res 62: 5027-34, 2002), (ii) Gleevec in BCR-ABL-transformed cells (Druker et al., Nat Med 2: 561-6, 1996) and (iii) a variety of less well-characterized compounds (Stockwell et al., Chew. Biol 6: 71-83, 1999; Torrance et al., Nat Biotechnol 19: 940-5, 2001).

Despite the research discussed above, there remains a significant need to develop and/or identify compounds that selectively target tumor cells.

SUMMARY OF THE INVENTION

A number of compounds / agents / drugs useful for treating or preventing cancer {e.g., tumors or leukemia) in an individual, such as a human in need of treatment or prevention, have been identified. As used herein, the terms "agent" and "drug" are used interchangeably; they can be compounds or molecules. These compounds generally have increased activity in the presence of one or more of the following: hTERT oncoprotein, the SV40 large T oncoprotein (LT), small T oncoprotein (ST), human papillomavirus type 16 (HPV) E6 oncoprotein, HPV E7 oncoprotein, and oncogenic HRAS, NRAS and KRAS. Over- expression of hTERT and either E7 or LT increases expression of topoisom erase 2a and overexpressing RAS ^vι2 and ST in cells expressing hTERT both increases expression of topoisomerase 1 and sensitizes cells to a non-apoptotic cell death process initiated by a compound of the invention.

In one embodiment, the invention provides compounds represented by Structural Formula (I):

or a pharmaceutically acceptable salt thereof, where: Ring A and B is optionally substituted; Ar is an optionally substituted phenyl group;

R₄ and R₅ are independently selected from the group consisting of -H, substituted or unsubstituted alkyl, substituted or unsubstituted alkenyl, substituted or unsubstituted alkynyl, substituted or unsubstituted non-aromatic heterocyclic and substituted or unsubstituted aryl, where alkyl, alkenyl and alkynyl are optionally interrupted by NR, O or S(O)_n; or R₄ and R₃ taken together form a 3- to S-membered carbocyclic or heterocyclic group;

V is

Q is a substituted or unsubstituted alkyl; each R is independently -H, substituted or unsubstituted alkyl, substituted or unsubstituted alkenyl, substituted or unsubstituted alkynyl, substituted or unsubstituted aryl or substituted or unsubstituted non-aromatic heterocyclic; and each n is independently 0, 1 or 2.

In another embodiment, the invention provides compounds represented by Structural Formula (U):

or a pharmaceutically acceptable salt thereof, where:

Rings A and B are optionally further substituted;

R_a is a halogen, substituted or unsubstituted alkyl, substituted or unsubstituted alkenyl, substituted or unsubstituted alkynyl, substitued or unsubstitued aryl-O-, substituted or unsubstituted alkyl-O-, substituted or unsubstituted alkenyl-O- or substituted or unsubstituted alkynyl-O- , where alkyl, alkenyl and alkynyl are optionally interrupted by NR₅ O or S(O)_n;

Rb is H, halogen, Ci_-8alkoxy or d-galkyl;

R₄ and Rs are independently selected from the group consisting of — H, substituted or unsubstituted alkyl, substituted or unsubstituted alkenyl, substituted or unsubstituted alkynyl, substituted or unsubstituted non-aromatic heterocyclic and substituted or unsubstituted aryl, where alkyl, alkenyl and alkynyl are optionally interrupted by NR, O or S(O)_n; or R₄ and Rs taken together form a 3- to 8-membered carbocyclic or heterocyclic group;

V is

Q is a substituted or unsubstituted alkyl group; each R is independently -H, substituted or unsubstituted alkyl, substituted or unsubstituted alkenyl, substituted or unsubstituted alkynyl, substituted or unsubstituted aryl or substituted or unsubstituted non-aromatic heterocyclic; and each n is independently 0, 1 or 2.

In yet another embodiment, the invention provides compounds represented by Structural Formula (111):

or a pharmaceutically acceptable salt thereof, where:

Rings A and B are optionally further substituted; Ri is a substituted or unsubstituted alkyl, substituted or unsubstituted alkenyl or substituted or unsubstituted alkynyl group, each of which is optionally interrupted by NR, O or S(O)_n;

R₄ and Rs are independently selected from the group consisting of -H, substituted or unsubstituted alkyl, substituted or unsubstituted alkenyl, substituted or unsubstituted alkynyl, substituted or unsubstituted non-aromatic heterocyclic and substituted or unsubstituted aryl, where alkyl, alkenyl and alkynyl are optionally interrupted by NR₅ O or S(O)_n; or R₄ and R₅ taken together form a 3- to 8-membered carbocyclic or heterocyclic group;

V is

In a further embodiment, the invention provides compounds represented by Structural Formula (I):

or a pharmaceutically acceptable salt thereof or a metabolic precursor thereof, wherein:

Ar is an optionally substituted phenyl group;

R₄ and R₅ are independently selected from the group consisting of -H, substituted or unsubstituted alkyl, substituted or unsubstituted alkenyl, substituted or unsubstituted alkynyl, substituted or unsubstituted non-aromatic heterocyclic and substituted or unsubstituted aryl, where alkyl, alkenyl and alkynyl are optionally interrupted by NR, O or S(O)_n; or R4 and R₅ taken together form a 3- to 8-membered carbocyclic or heterocyclic group; V is

;

Ring C is a substituted or unsubstituted heterocyclic aromatic or non-aromatic ring; A is NR or O; or A is a covalent bond;

L is a substituted or unsubstituted hydrocarbyl group optionally interrupted by one or more heteroatoms selected from N, O and S; Q is selected from the group consisting of -R¹, -C(O)R', -C(O)N(R)₂, -C(O)OR' and

-S(O)₂R'; each R is independently -H, substituted or unsubstituted alkyl, substituted or unsubstituted alkenyl, substituted or unsubstituted alkynyl, substituted or unsubstituted aryl or substituted or unsubstituted non-aromatic heterocyclic; each R' is independently a substituted or unsubstituted alkyl, substituted or unsubstituted alkenyl, substituted or unsubstituted alkynyl group, substituted or unsubstituted non-aromatic heterocyclic or substituted or unsubstituted aryl group; and each n is independently O, 1 or 2.

The compounds of the invention can be formulated with a pharmaceutically acceptable carrier as pharmaceutical compositions.

In further aspects of the invention, the invention relates to compounds disclosed herein that selectively kill or inhibit the growth of (are toxic to) engineered human tumorigenic cells and/or tumor cells.

In another embodiment, the present invention provides methods of treating a condition in a mammal, comprising administering to the mammal a therapeutically effective amount of a compound of the invention. Suitable. agents can have the recited activity in the existing form or after complete or partial metabolism

In certain embodiments, the condition is characterized by cells with substantially wild-type level of Rb activity. In certain such embodiments, the cells are further characterized by enhanced Ras signaling activity and/or altered (e.g., reduced or increased) activity of a cellular target protein of the SV40 small t antigen.

In certain aspects, the compound kills the cells by a non-apoptotic mechanism.

In certain aspects, the compound kills the cells by a mechanism other than a non- apoptotic mechanism (e.g., by apoptosis). In certain aspects, the cells have enhanced Ras pathway activity (e.g., RasV12), overexpress SV40 small t antigen, have substantially reduced activity of phosphatase PP2A, and/or modulate (e.g., enhance or inhibit) VDAC levels or activity, such as VDAC2 or VDAC3.

In certain aspects, the condition is cancer. In certain aspects, the cells are induced to express SV40 small t antigen, e.g., by infecting said cells with a viral vector overexpressing SV40 small t antigen, such as a retroviral vector or an adenoviral vector.

Another aspect of the invention provides a method of killing a cell, promoting cell death or inhibiting cellular proliferation, comprising administering to the cell an effective amount of a compound of the invention.

Suitable agents can have the recited activity in the existing form or after complete or partial metabolism

In certain embodiments, the cell is a cancer cell.

Tn certain aspects, the method also involves administering an agent that increases the abundance of VDAC (e.g., VDACl , VDAC2, VDAC3) in the cell. The agent for increasing the abundance of VDAC can, for example, include a polynucleotide encoding a VDAC, such as VDAC3; be a VDAC protein (e.g., VDAC3) adapted to be transported into the cell, e.g., fused with a heterologous internalization domain or formulated in liposome preparation; enhance endogenous VDAC (e.g., VDAC3) expression; stimulate VDAC (e.g., VDAC3) expression; or inhibit the function of a VDAC (e.g., VDAC3) inhibitor.

In certain aspects, the method also involves administering an agent that decreases the abundance of VDAC (e.g., VDACl , VDAC2, VDAC3) in the cell. The agent for decreasing the abundance of VDAC can, for example, inhibit endogenous VDAC (e.g., VDAC3) expression, suppress VDAC (e.g., VDAC3) expression or enhance the function of a VDAC (e.g., VDAC3) inhibitor.

In one embodiment, the present invention is a method of reducing the growth rate of a tumor, comprising administering an amount of a therapeutic agent sufficient to reduce the growth rate of the tumor, where the therapeutic agent is a compound of the invention. Suitable agents can have the recited activity in the existing form or after complete or partial metabolism.

In one aspect, the invention is a method for treating a patient suffering from a cancer, comprising administering to the patient an effective amount of a compound of the invention. Suitable agents can have the recited activity in the existing form or after complete or partial metabolism.

In another aspect, the invention is a method of increasing sensitivity of a tumor cell to a chemotherapeutic agent (e.g., additively or synergistically), where a tumor cell is contacted with a compound disclosed herein. In a related aspect, the invention is a method of reducing the sensitivity of a normal cell to a chemotherapeutic agent, where a normal cell is contacted with a compound disclosed herein.

In one embodiment, the invention is a method of identifying patients which are likely to respond to treatment with compounds of the invention. Using standard characterization methods known in the art, patients identified as possessing neoplasias displaying one or more of the following attributes would be expected to be responsive: aberrant Ras signaling ^• pathway activity as characterized by activation of one or more pathway members (e.g. phosphorylated Erkl/2, phosphorylated MEK etc.), and /or expression of VDAC proteins (1 , 2 or 3) and/or sensitivity of a cell line of similar or identical genotype to exposure of compounds of the invention either in vitro or in vivo.

In yet another embodiment, the invention is a method of conducting a pharmaceutical business, which includes:

(a) identifying a candidate therapeutic agent for inhibiting cell proliferation, where the candidate therapeutic agent is a compound disclosed herein, (b) conducting therapeutic profiling of the candidate therapeutic agent identified in step (a) for efficacy and toxicity in animals; and (c) formulating a pharmaceutical preparation including one or more the candidate therapeutic agent identified in step (b) as having an acceptable therapeutic profile.

Instead of or in addition to one or both of steps (b) and (c), the method can include licensing to a third party the rights for further development of the candidate therapeutic agent. In a further embodiment, the method of conducting a drug discovery business comprises establishing a distribution system for distributing the pharmaceutical preparation for sale. Optionally, a sales group is established for marketing the pharmaceutical preparation.

The present invention further provides packaged pharmaceuticals. In one embodiment, the packaged pharmaceutical comprises: (i) a therapeutically effective amount of a compound disclosed herein; and (ii) instructions and/or a label for administration of the agent for the treatment of patients having cancer. The instruction or label may be stored on an electronic medium such as CD, DVD, floppy disk, memory card, etc, which may be readable by a computer.

The present invention further provides use of a compound disclosed herein in the manufacture of a medicament for the treatment of cancer.

In certain embodiments, the methods of the invention further comprise conjointly administering one or more agents, such as chemotherapeutic agents that typically kill the cells through an apoptotic mechanism. Agents suitable for use in reducing the growth rate of a tumor and in treating a patient suffering from cancer include, but are not limited to, small organic molecules, peptides, proteins, peptidomimetics, nucleic acids, antibodies and combinations thereof.

It is contemplated that all embodiments of the invention can be combined with one or more other embodiments, even those described under different aspects of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 schematically shows the relationships among experimentally transformed human cells. BJ cells are primary human foreskin fibroblasts. BJ-TERT (also referred to as BJEH) cells are derived from BJ cells and express hTERT, the catalytic subunit of the enzyme telomerase. BJ-TERT/LT/ST cells are derived from BJ-TERT cells by introduction of a genomic construct encoding both simian virus 40 large (LT) and small T (ST) oncoproteins. BJ-TERT/LT/ST/RAS^{V I2} (also referred to as BJELR) tumor cells are derived from BJ-TERT/LT/ST cells by introduction of an oncogenic allele of HRAS (RAS^VI2) (Hahn et ciL, 1999, Nat Med 5, 1164-70). BJ-TERT/LT/RAS^VI2 cells are derived from BJ cells by introduction of cDNA constructs encoding TERT, LT, RAS^V12 and a control vector (Hahn et al, 2002, Nat Rev Cancer 2, 331-41). BJ-TERT/LT/RAS^VI2/ST cells are derived from BJ- TERT/LT/RAS^V12 cells by introduction of a cDNA encoding ST (Hahn et al, 2002, Nat Rev Cancer 2, 331 -41). TIP5 cells are primary human foreskin fibroblasts. The TIP5-derived cell lines were prepared by introducing vectors encoding hTERT, LT, ST, RAS, or the papillomavirus E6 or E7 proteins, as shown. E6 and E7 can jointly substitute for LT (Lessnick et al, 2002, Cancer Cell 1, 393-401).

FIG. 2 shows proteins identified by Western blot and SDS-PAGE from pull-down experiments using lysates from BJELR, BJEH, HT-1080 and PANC-I cells with Compound 1 immobilized on Affi-Gel 10 beads.

FIG. 3 shows proteins identified by Western blot and SDS-PAGE from pull-down experiments using lysates from BJELR cells with Compounds 1, 2 and 3 immobilized on Affi-Gel 10 beads.

DETAILED DESCRIPTION OF THE IN VEJNTION

The present invention provides compounds represented by Structural Formula (I)₃ where the compounds are suitable for use in the methods and compositions disclosed herein:

or a pharmaceutically acceptable salt thereof, where:

Ring A and B is optionally substituted;

Ar is an optionally substituted phenyl group;

R4 and R₅ are independently selected from the group consisting of — H, substituted or unsubstituted alkyl, substituted or unsubstituted alkenyl, substituted or unsubstituted alkynyl, substituted or unsubstituted non-aromatic heterocyclic and substituted or unsubstituted aryl, where alkyl, alkenyl and alkynyl are optionally interrupted by NR, O or S(O)_n; or R₄ and R5 taken together form a 3- to 8-membcrcd carbocyclic or heterocyclic group; V is

Q is a substituted or unsubstituted alkyl; each R is independently -H, substituted or unsubstituted alkyl, substituted or unsubstituted alkenyl, substituted or unsubstituted alkynyl, substituted or unsubstituted aryl or substituted or unsubstituted non-aromatic heterocyclic; and each n is independently 0, 1 or 2. Typically, V is

In certain embodiments, Q is a substituted alkyl (e.g., C₁-C₁₂ alkyl, such as C|-C₄ θr

C₃-Ci₂). Suitable examples of substituted alkyl groups include those substituted with a heteroatom, particularly halogens or substituents that are capable of forming hydrogen bonds such as -NHR (e.g., -NH₂) or -OH. Additional suitable substituents include alkoxy groups and poly(alkylene glycols) (e.g., polyethylene glycol). In certain embodiments, Q is substituted with a substituent other than —OH or -CN. Q is advantageously substituted at the terminal carbon.

In certain embodiments, Q is a Cs-C)₂ substituted or unsubstituted alkyl (e.g,. Cs-C₈). Suitable examples of substituted Cs-Ci₂ alkyl groups include those substituted with a heteroatom, particularly substituents that are capable of forming hydrogen bonds such as -NHR (e.g., -NH₂) or— OH. Q is advantageously substituted at the terminal carbon.

R₄ and R₅ are typically independently — H or a substituted or unsubstituted alkyl group (e.g., alkyl, alkoxyalkyl, mono- or dialkylaminoalkyl, aralkyl). More typically, R₄ and R5 are independently — H or a substituted or unsubstituted Ci-C₄ alkyl group, particularly where one is — H and the other is — H or a CpC₄ alkyl group.

In certain embodiments, Ring A is substituted with 1 -4 substituents, such as halogen or nitro. In certain embodiments, Ring A is substituted with one substituent, such as halogen or nitro, especially chloro, situated para to the carbonyl of the quinazolinone ring. In other embodiments, there are no substituents on Ring B (i.e., all substituents are hydrogen atoms).

In preferred embodiments of the present invention, Ar is a substituted phenyl. In certain embodiments, Ar is mono-substituted wherein the substituent is halogen, lower alkoxy, or lower alkyl. In certain embodiments, Ar has a substituent at the ortho position wherein the substituent is halogen, lower alkoxy, or lower alkyl. In certain embodiments, Ar is 2,6-disubstituted such that one substituent is halogen, lower alkoxy, or lower alkyl and the second substituent is halogen, lower alkoxy, or lower alkyl.

In certain embodiments, Ar has at least one halogen substituent. In certain embodiments, Ar has a halogen substituent in the ortho position. In preferred embodiments, the compounds of formula IV include those wherein Ar is a 2,6-disubstituted phenyl ring wherein the substituents are halogen atoms.

The present invention also provides compounds represented by Structural Formula (II), where the compounds are suitable for use in the methods and compositions disclosed herein:

or a pharmaceutically acceptable salt thereof, where:

Rings A and B are optionally further substituted;

R_n is a halogen, substituted or unsubstituted alkyl, substituted or unsubstituted alkenyl, substituted or unsubstituted alkynyl, substitued or unsubstitued aryl-O, substituted or unsubstituted alkyl-O-, substituted or unsubstituted alkenyl-O- or substituted or unsubstituted alkynyl-O- , where alkyl, alkenyl and alkynyl are optionally interrupted by NR, O or S(O)_n;

Rb is H, halogen, Ci-galkoxy or Cι_-8alkyl;

R4 and R₅ are independently selected from the group consisting of -H, substituted or unsubstituted alkyl, substituted or unsubstituted alkenyl, substituted or unsubstituted alkynyl, substituted or unsubstituted non-aromatic heterocyclic and substituted or unsubstituted aryl, where alkyl, alkenyl and alkynyl are optionally interrupted by NR, O or S(O)_n; or R₄ and R₅ taken together form a 3- to 8-membered carbocyclic or heterocyclic group;

V is

Typically, V is

In certain embodiments, Q is a substituted alkyl (e.g., C_I-C_I2 alkyl, such as C)-C₄ Or C3-C12). Suitable examples of substituted alkyl groups include those substituted with a heteroatom, particularly halogens or substituents that are capable of forming hydrogen bonds such as -NHR (e.g., -NH₂) or -OH. Additional suitable substituents include alkoxy groups and poly(alkylene glycols) (e.g., polyethylene glycol). In certain embodiments, Q is substituted with a substituent other than -OH or -CN. Q is advantageously substituted at the terminal carbon.

In certain embodiments, Q is a Cs-C)₂ substituted or unsubstituted alkyl (e.g,. Cs-Cs). Suitable examples of substituted C₅-C₁₂ alkyl groups include those substituted with a heteroatom, particularly substituents that are capable of forming hydrogen bonds such as -NHR (e.g., -NH₂) or —OH. Q is advantageously substituted at the terminal carbon.

R₄ and R₅ are typically independently — H or a substituted or unsubstituted alkyl group (e.g., alkyl, alkoxyalkyl, mono- or dialkylaminoalkyl, aralkyl). More typically, R₄ and R₅ are independently — H or a substituted or unsubstituted C₁-C₄ alkyl group, particularly where one is — H and the other is — H or a C₁-C4 alkyl group.

R₃ is typically a halogen or a substituted or unsubstituted alkyl-O- group, particularly where the alkyl portion is an unsubstituted C1-C4 alkyl group (e.g., methyl, ethyl, n-propyl, i- propyl, n-butyl, s-butyl, t-butyl). In one example, Ri is typically a substituted or unsubstituted alkyl-O- group. R_b is typically — H or a halogen. In certain embodiments,

Although Rings A and B are typically not further substituted in compounds of the invention (i.e., no substituents are present other than those specifically shown in the Structural Formula (H)), Rings A and B are substituted in certain embodiments. Suitable substituents include halogen, nitro, substituted or unsubstituted alkyl, substituted or unsubstituted aryl, substituted or unsubstituted non-aromatic heterocyclic, -CN, -COOR', -CON(R)₂, -SO₂N(R)₂, -OH and -OR', particularly nitro and halogen. In particular, when Ring A includes two or more nitrogen atoms, one of the nitrogen atoms advantageously is substituted with a substituted or unsubstituted alkyl or aryl, typically unsubstituted. Exemplary substituents for the nitrogen atom include methyl, ethyl, n-propyl, i-propyl and phenyl.

The present invention also provides compounds represented by Structural Formula (III), where the compounds are suitable for use in the methods and compositions disclosed herein:

or a pharmaceutically acceptable salt thereof, where:

Rings A and B are optionally further substituted;

Ri is a substituted or unsubstituted alkyl, substituted or unsubstituted alkenyl or substituted or unsubstituted alkynyl group, each of which is optionally interrupted by NR, O or S(O)_n;

R₄ and R₅ are independently selected from the group consisting of — H, substituted or unsubstituted alkyl, substituted or unsubstituted alkenyl, substituted or unsubstituted alkynyl, substituted or unsubstituted non-aromatic heterocyclic and substituted or unsubstituted aryl, where alkyl, alkenyl and alkynyl are optionally interrupted by NR, O or S(O)_n; or R₄ and R₅ taken together form a 3- to 8-membered carbocyclic or heterocyclic group;

V is

Q is a substituted or unsubstituted alkyl group; each R is independently -H₅ substituted or unsubstituted alkyl, substituted or unsubstituted alkenyl, substituted or unsubstituted alkynyl, substituted or unsubstituted aryl or substituted or unsubstituted non-aromatic heterocyclic; and each n is independently 0, 1 or 2. Typically, V is

In certain embodiments, Q is a substituted alkyl (e.g., CJ-C_{I 2} alkyl, such as Ci-C₄ Or C₃-C ₁₂). Suitable examples of substituted alkyl groups include those substituted with a heteroatom, particularly halogens or substituents that are capable of forming hydrogen bonds such as -NHR (e.g., -NH₂) or -OH. Additional suitable substituents include alkoxy groups and poly(alkylene glycols) (e.g., polyethylene glycol). In certain embodiments, Q is substituted with a substituent other than —OH or -CN. Q is advantageously substituted at the terminal carbon. In certain embodiments, Q is a Cs-Ci₂ substituted or unsubstituted alkyl (e.g_v Cs-Cs).

Suitable examples of substituted Cs-C]₂ alkyl groups include those substituted with a heteroatom, particularly substituents that are capable of forming hydrogen bonds such as -NHR (e.g., -NH₂) or -OH. Q is advantageously substituted at the terminal carbon.

R₄ and R₅ are typically independently -H or a substituted or unsubstituted alkyl group (e.g., alkyl, alkoxyalkyl, mono- or dialkylaminoalkyl, aralkyl). More typically, R₄ and R₅ are independently -H or a substituted or unsubstituted C]-C₄ alkyl group, particularly where one is -H and the other is -H or a Ci-C₄ alkyl group.

Ri is typically a substituted or unsubstituted alkyl group, particularly an unsubstituted Cj-C₄ alkyl group (e.g., methyl, ethyl, n-propyl, i-propyl, n-butyl, s-butyl, t-butyl). In one example, R| is typically a substituted or unsubstituted alkyl group when R₄, R5, V, W, X, Y and Z have the values described above.

Although Rings A and B are typically not further substituted in compounds of the invention (i.e., no substituents are present other than those specifically shown in the Structural Formula (III)), Rings A and B are substituted in certain embodiments. Suitable substituents include halogen, substituted or unsubstituted alkyl, substituted or unsubstituted aryl, substituted or unsubstituted non-aromatic heterocyclic, -CN, -COOR% -CON(R)₂, -SO₂N(R)₂, -OH and -OR'. Specific examples of compounds encompassed by Structural Formula (III) include Compounds (1) and (2).

The present invention also provides compounds represented by Structural Formula (1), where the compounds are suitable for use in the methods and compositions disclosed herein:

or a pharmaceutically acceptable salt thereof or a metabolic precursor thereof, where: Ar is an optionally substituted phenyl group;

R.4 and R₅ are independently selected from the group consisting of -H, substituted or unsubstituted alkyl, substituted or unsubstituted alkenyl, substituted or unsubstituted alkynyl, substituted or unsubstituted non-aromatic heterocyclic and substituted or unsubstituted aryl, where alkyl, alkenyl and alkynyl are optionally interrupted by NR, O or S(O)_n; or R₄ and R₅ taken together form a 3- to 8-membered carbocyclic or heterocyclic group; V is -NH-L-A-Q-NHR or

L is a substituted or unsubstituted hydrocarbyl group optionally interrupted by one or more heteroatoms selected from N, O and S;

Q is selected from the group consisting of -R', -C(O)R', -C(O)N(R)₂, -C(O)OR' and -S(O)₂R'; each R is independently -H, substituted or unsubstituted alkyl, substituted or unsubstituted alkenyl, substituted or unsubstituted alkynyl, substituted or unsubstituted aryl or substituted or unsubstituted non-aromatic heterocyclic; each R' is independently a substituted or unsubstituted alkyl, substituted or unsubstituted alkenyl, substituted or unsubstituted alkynyl group, substituted or unsubstituted non-aromatic heterocyclic or substituted or unsubstituted aryl group; and each n is independently O, 1 or 2. For certain compounds of the invention, V is

. Suitable examples of .V encompassed by the above structure include

.

When V is represented by one of these structures, A is typically a covalent bond or NR. Particularly suitable examples of V are

where A is a covalent bond; and

where A is NR.

The substituent -Q-NHR in compounds of the invention, particularly compounds where V is as represented above, is typically an amino-substituted acyl group or an amino- substitued alkyl group. Acy! groups typically are represented by -C(O)R'-NHR, where R' is as defined above. In certain embodiments, R' in -C(O)R' -N HR is an amino-substituted aryl or aryloxyalkyl group, particularly an amino-substituted phenyl or phenyloxyalkyl group such as an amino-substituted or unsubstituted phenyl oxymethyl group. The amino substituent on such groups may be part of an aminoalkyl group. Preferred amino-substituted phenyloxymethyl group include aminophenoxymethyl, aminomethylphenoxymethyl and arninoethylphenoxymethyl.

As used herein, "metabolic precursor thereof refers to the -NHR moiety of -Q-NHR, in that the invention includes function groups that are metabolically converted to -Q-NHR, such as amide derivatives thereof.

R₄ and R₅ are typically independently — H or a substituted or unsubstituted alkyl group (e.g., alkyl, alkoxyalkyl, mono- or dialkylaminoalkyl, aralkyl). More typically, R₄ and R5 are independently — H or a substituted or unsubstituted C₁-C₄ alkyl group, particularly where one is — H and the other is the Ci -C₄ alkyl group.

In certain embodiments, Ring A is substituted with 1-4 substituents, such as halogen or nitro. In certain embodiments, Ring A is substituted with one substituent, such as halogen or nitro, especially chloro, situated para to the carbonyl of the quinazolinone ring. In other embodiments, there are no substituents on Ring B (i.e., all substituents are hydrogen atoms). In preferred embodiments of the present invention, Ar is a substituted phenyl. In certain embodiments, Ar is mono-substituted wherein the substituent is halogen, lower alkoxy, or lower alkyl. In certain embodiments, Ar has a substituent at the ortho position wherein the substituent is halogen, lower alkoxy, or lower alkyl. In certain embodiments, Ar is 2,6-disubstituted such that one substituent is halogen, lower alkoxy, or lower alkyl and the second substituent is halogen, lower alkoxy, or lower alkyl.

In certain embodiments, Ar has at least one halogen substituent. In certain embodiments, Ar has a halogen substituent in the ortho position. In preferred embodiments, Ar is a 2,6-disubstituted phenyl ring wherein the substituents arc halogen atoms. In certain embodiments, Ar is represented by the following formula:

where R_n and R_b have the values described above for Structural Formula (II) and Ring B can be optionally further substituted as described above for Structural Formula (II). In certain such embodiments, Ar is represented by the following formula:

where Ri has the values described above for Structural Formula (III) and Ring B can be optionally further substituted as described above for Structural Formula (III).

An example of a compound encompassed by Structural Formula (I) is Compound (3):

In certain embodiments, the invention does not include one or more of the following compounds, which are disclosed in U.S. Application No. 1 1/340,430, filed January 25, 2006, the contents of which are incorporated herein by reference:

Compounds included in the invention include enantiomers and diastereomers of the compounds disclosed herein. The invention also includes salts, particularly pharmaceutically acceptable salts of the compounds disclosed herein. In addition, the invention includes solvates, hydrates and polymorph crystalline forms of the compounds disclosed herein.

The term "acyl" as used herein includes such moieties as can be represented by the general formula:

O

.R

wherein suitable R groups, include, but are not limited to H, alkyl, alkoxy, aralkyl, aryloxy, aryl, heteroaryl, heteroaralkyl, heteroaryloxy, and cycloalkyl, wherein any of these groups may optionally be further appropriately substituted.

The term "hydrocarbyl" refers to substituted or unsubstituted, cyclic or acyclic, saturated or unsaturated hydrocarbon groups. When indicated, hydrocarbyl atoms can be interrupted by one or more heteroatoms such as N, O and S (i.e., the heteroatoms are not at a terminus of the group). The term "alkyl" refers to substituted or unsubstituted saturated hydrocarbon groups, including straight-chain alkyl and branched-chain alkyl groups, including haloalkyl groups such as trifluoromethyl and 2,2,2-tirfluoroethyl, etc. Co alkyl indicates a hydrogen where the group is in a terminal position, a bond if internal. The terms "alkenyl" and "alkynyl" refer to substituted or unsubstituted unsaturated aliphatic groups analogous possible substitution to the alkyls described above, but that contain at least one double or triple bond respectively.

The term "alkoxy" refers to an oxygen having an alkyl group attached thereto.

Representative alkoxy groups include methoxy, ethoxy, propoxy, tert-butoxy and the like. An "ether" is two hydrocarbons covalently linked by an oxygen. Accordingly, the substituent of an alkyl that renders that alkyl an ether is or resembles an alkoxy.

The term "aralkyl", as used herein, refers to an alkyl group substituted with an aryl group.

The term "carbocyclic" as used herein includes 3- to 8-membered substituted or unsubstituted single-ring saturated or unsaturated cyclic aliphatic groups in which each atom of the ring is carbon. The term "heterocyclic" as used herein includes 3- to 8-membered, preferably 4- to 8- membered, substituted or unsubstituted single-ring cyclic groups in which the ring includes 1 to 3 heteroatoms. Examples of non-aromatic heterocyclic groups include pyrrolidine, piperadine, piperazine, tetrahydrofuran and tetrahydrothiophene. The term "aryl" as used herein includes 5-, 6-, and 7-membered substituted or unsubstituted single-ring carbocyclic or heterocyclic aromatic groups. The term "aryl" also includes polycyclic ring systems having two or more cyclic rings in which two or more carbons are common to two adjoining rings wherein at least one of the rings is aromatic, e.g., the other cyclic rings can be cycloalkyls, cycloalkenyls, cycloalkynyls, aryls and/or heterocyclyls. Carbocyclic aryl groups include benzene, naphthalene, phenanthrene, phenol, aniline, and the like. The term "heteroaryl" includes substituted or unsubstituted aromatic 5- to 7-membered ring structures, more preferably 5- to 6-membered rings, whose ring structures include one to four heteroatoms. The term "heteroaryl" also includes polycyclic ring systems having two or more cyclic rings in which two or more carbons are common to two adjoining rings wherein at least one of the rings is heteroaromatic, e.g., the other cyclic rings can be cycloalkyls, cycloalkenyls, cycloalkynyls, aryls, and/or heterocyclyls. Heteroaryl groups include, for example, pyrrole, furan, thiophene, imidazole, oxazole, thiazole, triazole, pyrazole, pyridine, pyrazine, pyridazine and pyrimidine, and the like. The term "heteroatom" as used herein means an atom of any element other than carbon or hydrogen. Preferred heteroatoms are nitrogen, oxygen, phosphorus, and sulfur.

The terms "polycyclyl" or "polycyclic" refer to two or more rings {e.g., cycloalkyls, cycloalkenyls, cycloalkynyls, aryls, heteroaryls, and/or heterocyclyls) in which two or more carbons are common to two adjoining rings, e.g., the rings are "fused rings". Each of the rings of the polycycle can be substituted or unsubstituted. The term "substituted" refers to moieties having substituents replacing a hydrogen on one or more carbons of the backbone. It will be understood that "substitution" or "substituted with" includes the implicit proviso that such substitution is in accordance with permitted valence of the substituted atom and the substituent, and that the substitution results in a stable compound, e.g., which does not spontaneously undergo transformation such as by rearrangement, cyclization, elimination, etc. As used herein, the term "substituted" is contemplated to include all permissible substituents of organic compounds. In a broad aspect, the permissible substituents include acyclic and cyclic, branched and unbranched, carbocyclic and heterocyclic, aromatic and non-aromatic substituents of organic compounds. The permissible substituents can be one or more and the same or different for appropriate organic compounds. For purposes of this invention, the heteroatoms such as nitrogen may . have hydrogen substituents and/or any permissible substituents of organic compounds described herein which satisfy the valences of the heteroatoms. Substituents can include, for example, a halogen, a hydroxyl, a carbonyl (such as a carboxyl, an alkoxycarbonyl, a formyl, or an acyl), a thiocarbonyl (such as a thioester, a thioacetate, or a thioformate), an alkoxyl, a phosphoryl, a phosphate, a phosphonate, a phosphinate, an amino, an amido, an amidine, an imine, a cyano, a nitro, an azido, a sulfhydryl, an alkylthio, a sulfate, a sulfonate, a sulfamoyl, a sulfonamido, a sulfonyl, a heterocyclyl, an aralkyl, or an aromatic or heteroaromatic moiety. It will be understood by those skilled in the art that the moieties substituted on the hydrocarbon chain can themselves be substituted, if appropriate.

The term "small organic molecule" refers to a non-polymeric compound having a molecular weight of less than 2000 amu. Typically, such molecules have a molecular weight of less than 1000 amu, such as less than 500 amu.

Selective Cell Killing

The ability of genotype-selective compounds to serve as molecular probes is based on the premise of chemical genetics, that small molecules can be used to identify proteins and pathways underlying biological effects (Schreiber, 1998, Bioorg. Med. Chem. 6, 1 127-1 152; Stockwell, 2000, Nat Rev Genet 1, 116-25; Stockwell, 2000, Trends Biotechnol J 8, 449-55). For example, the observation that the natural product rapamycin retards cell growth made possible the discovery of the mammalian Target of Rapamycin (mTOR) as a protein that regulates cell growth (Brown et ah, 1994, Nature 369, 756-758; Sabatim et al., \994, Cell 78, 35-43). A series of human tumor cells have been engineered with defined genetic elements for use in identifying those critical pathways whose disruption leads to a tumorigenic phenotype (Hahn et al., 1999, Nat Med 5, 1 164-70; Hahn et al., 2002, Nat Rev Cancer 2, 331 -41 ; Lessnick et al., 2002, Cancer Cell 1 , 393-401). It is expected that these experimentally transformed cells will enable identification of genotype-selective agents that exhibit synthetic lethality in the presence of specific cancer-related alleles. Compounds with genotype- selective lethality may serve as molecular probes of signaling networks present in tumor cells, as leads for subsequent development of clinically effective drugs with a favorable therapeutic index and/or as an effective drug. The invention provides compounds that kill cancer cells, especially genotype-specific cancer cells, such as those with elevated Ras signaling activity, altered SV40 small t antigen target activity, and/or substantially intact Rb activity.

Thus, one aspect of the invention provides a method to selectively kill cancer cells, especially those with elevated Ras activity, altered SV40 small t antigen target activity, and preferably substantially intact Rb and/or p53 activity, the method comprising administering to a mammalian patient in need of treatment a therapeutically effective amount of a compound disclosed herein.

As is well-known in the art, the constitutive activation of Ras appears to be an important factor for the malignant growth of human cancer cells. Mutations of the RAS proto-oncogenes (H-RAS, N-RAS, K-RAS) are frequent genetic aberrations found in 20% to 30% of all human tumors, although the incidences in tumor type vary greatly (Bos, Cancer Res. 49: 4682-4689, 1989). The highest rates of RAS mutations were detected in adenocarcinomas of the pancreas (90%), the colon (50%), and the lung (30%). In follicular and undifferentiated carcinomas of the thyroid, the incidence of RAS mutations is also considerable (50%). The most commonly observed RAS mutations arise at sites critical for Ras regulation — namely, codons 12, 13, and 61. Each of these mutations results in the abrogation of the normal GTPase activity of Ras. Ras activation is also frequently observed in hematologic malignancies such as myeloid leukemias and multiple myelomas. In about one-third of the myelodysplastic syndromes (MDS) and acute myeloid leukemias (AML), RAS genes are mutationally activated. RAS mutations occur in about 40% of newly diagnosed multiple myeloma patients, and the frequency increases with disease progression. On the other hand, polyomaviruses infect a wide variety of vertebrates (12 members now known). Murine polyomavirus was isolated by Ludwig Gross in 1953 while he was studying leukemia in mice and named because it caused solid tumors at multiple sites. The second member of the family, Simian Vacuolating Virus 40 (SV40) was isolated by Sweet and Hilleman in 1960 in primary monkey kidney cells cultures being used to grow Sabin OPV (Hilleman, Dev Biol Stand 94: 183-190, 1998). Two human polyomaviruses were isolated in 1971, cBK Virus (BKV) and JC Virus (JCV). The polyomaviruses encode three proteins involved in cellular transformation termed large tumor antigen (LT), middle T antigen (mT), and small tumor antigen (sT). These three proteins result from the differential splicing of the early region transcript and contain homologous sequences. The large T antigen of polyoma interacts with the tumor suppressor protein, pRb and is able to immortalize primary fibroblasts in culture. The Dna J domain located at its N-terminus, particularly the HPDKYG sequence found between residues 42 and 47, is critical for functional inactivation of Rb family proteins, as is also the case with SV40 large T antigen. The expression of LT is not sufficient to produce a fully transformed cell phenotype - this requires mT, which is the major transforming protein of the polyomavirus. Mouse polyoma middle T consists of 421 amino acids and can be divided into at least three domains, some of which are shared with LT and sT. The amino terminal domain comprises the first 79 amino acids and is also present in LT and sT. Adjacent to it, between residues 80- 192, is a domain that is also present in the polyoma sT and contains two cysteine rich regions, Cys-X-Cys-X-X-Cys, which have also been identified in small t of SV40. Mutation of these cysteines abolishes the ability of mT to transform cells. The remaining 229 amino acids are unique to mT and contain the major tyrosine phosphorylation site of mouse mT and a hydrophobic region (approximately 20 amino acids at the carboxy-terminus) involved in membrane localization of this protein which is necessary for its transforming activity. Small t antigen of SV40 comprises 174 amino acids. The region between residues 97-

103 interacts with the protein phosphatase 2A (PP2A). This interaction reduces the ability of PP2A to inactivate ERKl and MEKl protein kinases, resulting in stimulation of proliferation of quiescent monkey kidney cells. Small t antigen-dependent assays also identified other regions which had the ability to enhance cellular transformation. These regions are located in the N-terminal part which is shared by the small and large T antigens of S V40 and can potentially function as a Dna J domain. Small t antigen can also associate with tubulin and it has been suggested that this plays a role in its biological function.

Cells with both activated Ras activity and small t antigen expression (and thus diminished small t antigen target protein activity, e.g., diminished PP2A, etc., or enhanced ERKl and MEKl) can be selectively killed by compounds disclosed herein, likely via a non- apoptotic mechanism. In a preferred embodiment, the cell expresses a substantially wild-type level of Rb and/or p53 (or other E6/E7 protein targets).

Thus, in certain embodiments, cancer cells of certain specific genotypes can be selectively killed by the compounds of the invention. These may include cancers harboring constitutively active Ras mutations or Ras signaling pathway mutations, and enhanced ERKl , MEKl activity or reduced PP2A activity.

In certain other embodiments, the genotype of the target cells may be selectively altered (e.g., to express small t antigen of SV40, express ERKl or MEKl, or inhibit PP2A, etc.), so that target cells previously not susceptible to compounds of the invention are now susceptible to killing by these compounds.

In certain embodiments, the invention provides a method of selectively killing cancer cells that have elevated Ras activity and small t antigen expression (or altered small t antigen target protein activity, such as PP2A activity, enhanced ERKl or MEKl activity or a mechanism that mimics the effects of sT, including but not limited to mutations in the PP2 A regulatory subunit), while protecting relatively normal cells that do not have elevated Ras activity, even when these cells also express small t antigen. This can be useful since many cancers harbor the somatic RasV12 or other similar mutations leading to elevated Ras signaling activity in cancer cells, while normal cells in the same patient / individual usually do not have the same Ras Vl 2 or other Ras pathway mutations. Compounds of the invention can be used to selectively kill these cancer cells, if the cancer cells also express small t antigen (or have altered small t antigen target protein activity). Even though other normal cells in the individual / patient also express the small t antigen, the subject method would still be effective in killing cancer cells since normal cells likely do not have elevated Ras signaling activity. Even if the individual does not express small t antigen, small t antigen may be delivered to the patient (either as protein or as vector-encoded DNA) to confer susceptibility to killing by compounds of the invention in cancer (but not normal) cells. Since small t antigen by itself is not understood to be sufficient to induce adverse effects on the patient, the side effects of the treatment (providing small t antigen to the patient) would be minimal or non-existent. In fact, as many as 30 million Americans are thought to have been exposed to SV40 through polio vaccinations between 1955 and 1963. SV40 found its way into the vaccine through macaque kidney cells used to grow polio virus. That method is no longer used and polio vaccines have been free of the virus since 1963. DNA studies in the 1990's found SV40 in some human tumors. However, association of virus DNA with dividing cells in tumor tissue does not prove that the virus caused the formation of the tumor. In October 2002, a scientific panel from the U.S. Institute of Medicine concluded that there is no way to determine whether widespread use of polio vaccine contaminated with simian virus SV40 decades ago led to increased cancer rates in humans. In some embodiments, the elevated Ras activity is manifested by a constitutively active Ras (N-, H-, or K- Ras) mutation at amino acid positions 12, 13, and/or 61. In some other embodiments, the elevated Ras activity is manifested by. enhanced activity of one or more downstream components of the Ras pathway proteins, including but are not limited to Raf, MEK, MAPK, etc.

In yet other embodiments, the small t antigen expression can be accomplished by infection of target cells with vectors, such as adenoviral or retroviral vectors expressing SV40 small t antigen (see below).

Alternatively, the small t antigen may be directly provided to the target cells. For example, small t antigen may be introduced into the target cells using various methods known in the art (see details below). In one embodiment, the small t antigen may be provided to the target cell by entrapping it in liposomes bearing positive charges on their surface (e.g., lipofectins) and which are optionally tagged with antibodies against cell surface antigens of the target tissue, e.g., antibodies against a cancer cell surface antigen. In another embodiment, the small t antigen may be provided to the target cells by transcytosis, using any of the "internalizing peptides" capable of mediating this effect, including but not limited to the N- terminal domain of the HIV protein Tat (e.g., residues 1-72 of Tat or a smaller fragment thereof which can promote transcytosis), all or a portion of the Drosophila antenopedia III protein, a sufficient portion of mastoparan, etc. (see below).

In other embodiments, the diminished PP2A (and/or other small t antigen target proteins) may be achieved by delivering an antibody, RNAi (siRNA, short hairpin RNA, etc.), antisensc sequence, or small molecule inhibitor specific for such target protein.

Delivery of such antagonists of a protein to a target cell is well known in the art. See, for example, WO04078940A2, EP1439227A1, WO04048545A2, US20040029275A1 , WO03076592A2, WO04076674A1, WO9746671 Al , all incorporated herein by reference.

. Another aspect of the invention provides a conjoint therapeutic method using compounds of the invention and one or more agents or therapies (e.g., radiotherapy) that kill cells via an apoptotic mechanism. Such agents include many of the chemotherapeutic drugs described below.

It is believed that certain proteins have elevated expression levels in cells sensitive to compounds of the invention. One such protein, VDAC3, is elevated 2-2.5 fold in abundance when exposed to erastin, for example, and, while Applicants do not wish to be bound by theory, its presence or even increased abundance is believed to be essential for killing mediated by compounds of the invention. Thus in another aspect of the invention, a method is provided to kill or slow the rate of proliferation of cells that have an elevated level of a VDAC such as VDAC2 or VDAC3, comprising contacting the target cells with a compound of the invention.

In certain embodiments, target cells are manipulated to express a higher level of a VDAC such as VDAC2 or VDAC3 so as to enhance the susceptibility of killing or slowing the rate of proliferation by compounds of the invention.

For example, a VDAC protein may be introduced into the target cells using various methods known in the art (see details below). In one embodiment, the VDAC protein may be provided to the target cell by entrapping it in liposomes bearing positive charges on their surface {e.g., lipofectins) and which are optionally tagged with antibodies against cell surface antigens of the target tissue, e.g., antibodies against a cancer cell surface antigen. In another embodiment, the VDAC protein may be provided to the target cells by transcytosis, using any of the "internalizing peptides" capable of mediating this effect, including but not limited to the N-terminal domain of the HIV protein Tat {e.g., residues 1-72 of Tat or a smaller fragment thereof which can promote transcytosis), all or a portion of the Drosophila antennapedia III protein, a sufficient portion of mastoparan, etc. (see below).

Alternatively, nucleic acids encoding a functional VDAC may be introduced into such target cells, using, for example, adenoviral or retroviral vectors expressing VDAC.

In addition, endogenous VDAC (e.g., VDAC3) activity may be stimulated by an agent that either stimulates VDAC expression, or suppresses the activity of a VDAC inhibitor

(transcription or translation inhibitor, or inhibitor that promotes VDAC turnover in the cell).

In certain aspects, the method of the invention also involves administering an agent that increases the abundance of VDAC (e.g. VDACl , VDAC2, VDAC3) in the cell. The agent for increasing the abundance of VDAC can, for example, include a polynucleotide encoding VDAC, such as VDAC3; be a VDAC protein (e.g., VDAC3) adapted to be transported into the cell, e.g., fused with a heterologous internalization domain or formulated in liposome preparation.

In certain aspects, the method of the invention also involves administering an agent that decreases the abundance of VDAC (e.g. VDACl, VDAC2, VDAC3) in the cell. The agent for decreasing the abundance of VDAC can, for example, inhibit endogenous VDAC (e.g. VDAC3) expression, suppress VDAC (e.g. VDAC3) expression or enhance the function of a VDAC (e.g., VDAC3) inhibitor. The following sections describe certain exemplary embodiments of the invention, which are contemplated to be capable to combining with one another. In addition, the embodiments are for illustrative purposes only, and should not be construed to be limiting in any respect. •^■

Engineered Cell Lines

Previous reports have indicated that it is possible to convert primary human cells into tumorigenic cells by introduction of vectors expressing the hTERT and oncogenic RAS proteins as well as others that disrupt the function of p53, RB and PP2A (Hahn et al., 2002, MoI Cell Biol 22, 2111-23; Hahn et al., 1999, Nature 400, 464-8; Hahn and Weinberg, 2002, Nat Rev Cancer 2, 331-41 ; Lessnick et al., 2002, Cancer Cell 1, 393-401). A series of engineered human tumorigenic cells and their precursors, which were created by introducing specific genetic elements into primary human foreskin fibroblasts (FlG. 1), can be used in the assays described herein. A variety of characteristics of these engineered tumorigenic cells have been reported previously, including their doubling time, their resistance to replicative senescence and crisis in culture, their response to gamma irradiation, their ability to grow in an anchorage-independent fashion and their ability to form tumors in immunodeficient mice (Hahn et al., 1999, supra; Hahn et al., 2002, supra; Lessnick et al., 2002, supra).

In one series of engineered cells, the following genetic elements were introduced sequentially into primary BJ fibroblasts: the human catalytic subunit of the enzyme telomerase (hTERT), a genomic construct encoding the Simian Virus 40 large (LT) and small T (ST) oncoproteins, and an oncogenic allele of HRAS (RAS^VI2). The resulting transformed cell lines were named, respectively: BJ-TERT, BJ-TERT/LT/ST, and BJ- TERT/LT/ST/RAS^VI2. In a second series, cell lines were created in which complementary DNA (cDNA) constructs encoding LT and ST were used in place of the SV40 genomic construct that encodes both of these viral proteins. In this latter series, ST was introduced in the last stage, such that compounds can be tested in the presence or absence of ST. This latter engineered human tumorigenic cell line was named BJ-TERT/LT/RAS^{V 12}/ST.

In a third series, cell lines derived from independently prepared human TIP5 foreskin fibroblasts created by introducing cDNA constructs encoding hTERT, LT, ST and RAS^VI2 (Lessnick et al., 2002, Cancer Cell 1 , 393-401) were used. These cell lines were called, respectively: TIP5/TERT, T1P5/TERT/LT, TIP5/TERT/LT/ST, and TIP5/TERT/LT/ST/RAS^VI2. In a fourth series, cell lines derived from TIP5 fibroblasts created by introducing cDNA constructs encoding hTERT, E6, E7, ST and RAS^VI2 were used. These cell lines were named, respectively: TIP5/TERT/E6, TIP5/TERT/E6/E7, TIP5/TERT/E6/E7/ST, and TIP5/TERT/E6/E7/ST/RAS^VI2. In this series, HPV E6 and E7, which inactivate p53 and RB, respectively, serve a similar function as LT in the previous series. However, by using HPV E6 and E7, the effects of inactivating, separately and independently, p53 and RB can be observed.

Methods of Screening for Genotype-Selective Compounds As used herein, the terms agent and drug are used interchangeably. As used herein, the term "is toxic to" refers to the ability of an agent or compound to kill or inhibit the growth/proliferation of tumorigenic cells. Large-scale screens include screens wherein hundreds or thousands of compounds are screened in a high- throughput format for selective toxicity to engineered tumorigenic cells. In one embodiment of the invention, selective toxicity is determined by comparing cell viability of test cells, which are engineered tumorigenic cells, and control cells after contact with a candidate agent. An appropriate control is a cell that is the same type of cell as that of test cells except that the control cell is not engineered to be tumorigenic. For example, control cells may be the parental primary cells from which the test cells are derived. Control cells are contacted with the candidate agent under the same conditions as the test cells. An appropriate control may be run simultaneously, or it may be pre-established (e.g., a pre-established standard or reference). Cell viability may be determined by any of a variety of means known in the art, including the use of dyes such as calcein acetoxymethyl ester (calcein AM) and Alamar Blue. In certain embodiments of the invention, a dye such as calcein AM is applied to test and control cells after treatment with a candidate agent. In live cells, calcein AM is cleaved by intracellular esterases, forming the anionic fluorescent derivative calcein, which cannot diffuse out of live cells. Hence, live cells exhibit a green fluorescence when incubated with calcein AM, whereas dead cells do not. The green fluorescence that is exhibited by live cells can be detected and can thereby provide a measurement of cell viability. In certain embodiments of the invention, an agent that has been identified as one that selectively induces cell death in an engineered tumorigenic cell is further characterized in an animal model. Animal models include mice, rats, rabbits, and monkeys, which can be nontransgenic (e.g., wildtype) or transgenic animals. The effect of the agent that selectively induces cell death in engineered turaorigenic cells may be assessed in an. animal model for- any number of effects, such as its ability to selectively induce cell death in tumorigenic cells in the animal and its general toxicity to the animal. For example, the method can comprise further assessing the selective toxicity of an agent (drug) to tumorigenic cells in an appropriate mouse model.

The effect of the agent that induces death in engineered tumorigenic cells may be assessed in an animal model for any number of effects, such as its ability to induce death in tumorigenic cells in the animal and its general toxicity to the animal. For example, the method can comprise further assessing the toxicity of an agent (drug) to tumorigenic cells in an appropriate mouse model. To illustrate, an agent can be further evaluated by using a tumor growth assay which assesses the ability of tested agent to inhibit the growth of established solid tumors in mice. The assay can be performed by implanting tumor cells into the fat pads of nude mice. Tumor cells are then allowed to grow to a certain size before the agents are administered. The volumes of tumors are monitored for a set number of weeks, e.g., three weeks. General health of the tested animals is also monitored during the course of the assay.

An agent that has been identified as one that selectively kills or inhibits the growth/proliferation of engineered tumorigenic cells can be further characterized in cell- based assays to assess its mechanism of action. For example, the agent can be tested in apoptosis assays to assess its ability to induce cell death by means of a pro-apoptotic pathway. In addition, an agent that induces death in tumor cells can be assessed for its ability to induce death in tumorigenic cells by a non-apoptotic pathway. For example, the agent can be tested in apoptosis assays to assess its inability to induce cell death by means of a pro- apoptotic pathway. If the viability of the test cells is more than that of the control cells in the assays described above, then an agent (drug) that selectively suppresses the cellular toxicity is identified. Control cells are contacted with the candidate agent under the same conditions as the test cells. An appropriate control may be run simultaneously, or it may be pre-established (e.g., a pre-established standard or reference). Genotype-Selective Compounds of the Invention

One effect of introducing TERT and one or more of LT, ST, E6, E7 and oncogenic RAS into normal human cells is to increase the rate of cell proliferation and to allow sensitivity to small molecules that inhibit DNA synthesis. Although it is well established that such agents preferentially target rapidly replicating tumor cells, it is reassuring to see this principle emerge from this unbiased screening approach. Moreover, the methodology made it possible to readily distinguish between compounds that have a clear basis for genetic selectivity and those that do not.

Results showed that expression of hTERT and either E7 or LT sensitizes cells to topoisomerase II poisons. Since loss or inactivation of RB (Sellers and Kaelin, 1997, J Clin Oncol 15, 3301-12; Sherr, 2001, Nat Rev MoI Cell Biol 2, 731-7) and activation of telomerase (Hahn and Weinberg, 2002, Nat Rev Cancer 2, 331-41; Harley, 1994, Pathol Biol (Paris) 42, 342-5) are found in most human cancers, these observations may explain, in part, the activity of these agents in a diverse range of human tumor types.

One aspect of the ability of ST to transform human cells along with RAS^VI2, LT and hTERT may be the effect of ST and RAS^VI2 on expression of topoisomerase I. Mutations in HRAS and KRAS have been described in many types of human cancers. Moreover, the inactivation of PPP2R1 B, a component of PP2A, has recently been reported in colon and lung tumors (Wang et al., 1998, Science 282, 284-7), while mutations in a different PP2A subunit have been described in melanoma, lung, breast and colon cancers (Calin et al., 2000, Oncogene 19, i 191-5; Kohno et al., 1999, Cancer Res 59, 4170-4; Ruediger et al., 2001 , Oncogene 20, 1892-9; Ruediger et al., 2001, Oncogene 20, 10-5). At present, it remains unclear whether simultaneous alteration of these two pathways occurs at high frequency in human tumors or whether cancers in which both of these pathways are perturbed show increased susceptibility to these compounds.

Expression of RAS^V12 leads to the activation of several well-characterized signaling pathways, including the RAF-MEK-MAPK signaling cascade, the phosphatidylinositol 3- kinase (P13K) signaling pathway and the Ral-guanine dissociation factor pathway (RaI-GDS). Each of these pathways has been implicated in human cancers, and recent work demonstrates that these pathways work in concert in this system of cell transformation (Hamad et al., 2002, Genes Dev 16, 2045-57). In addition, ST binds to and inactivates PP2A, a widely expressed serine-threonine phosphatase. Although the specific enzymatic targets of PP2A that are perturbed upon expression of ST are not yet known, there is substantial overlap among pathways altered by PP2A and RAS (Millward et al., 1999, Trends Biochem Sci 24, 186-91). Methods of Identifying Targets for Genotype-Selective Compounds

In certain embodiments, the invention relates to the use of compounds of the invention, also referred to herein as "ligand", to identify targets (also referred to herein as "cellular components" (e.g., proteins, nucleic acids, or lipids) involved in conferring the phenotype of diseased cells.

In one embodiment, the invention provides a method to identify cellular components involved in rumorigenesis, whereby a tumorigenic cell, such as an engineered human tumori genie cell, tissue, organ, organism or a lysate or an extract thereof is contacted with a subject anti-tumor compound; and after contact, cellular components that interact (directly or indirectly) with a ligand are identified, resulting in identification of cellular components involved in tumorigenesis. In another embodiment, the invention provides a method to identify cellular components involved in tumorigenesis. In this method, (a) a tumorigenic cell, such as an engineered human tumorigenic cell, tissue, organ, organism or a lysate or an extract thereof is contacted with an inhibitor of a ligand and contacted with the ligand; and (b) cellular components that interact (directly or indirectly) with the inhibitor of the ligand are identified, which cellular components are involved in tumorigenesis. The cell can be contacted with the ligand and the inhibitor of the ligand sequentially or simultaneously. Cellular components that interact with the ligand or any agent of the present invention may be identified by known methods. As described herein, the subject compound (or ligand) of these methods may be created by any chemical method. The ligand may be optionally derivatized with another compound. One advantage of this modification is that the derivatizing compound may be used to facilitate ligand target complex collection or ligand collection, e.g., after separation of ligand and target. Non-limiting examples of derivatizing groups include biotin, fluorescein, digoxygenin, green fluorescent protein, isotopes, polyhistidine, magnetic beads, glutathione S transferase, photoactivatible crosslinkers or any combinations thereof. Derivatizing groups can also be used in conjunction with targets (e.g., an erastin binding protein) in order to facilitate their detection.

According to the present invention, a target (cellular component) may be a naturally occurring biomolecule synthesized in vivo or in vilro. A target may be comprised of amino acids, nucleic acids, sugars, lipids, natural products or any combinations thereof. An advantage of the instant invention is that no prior knowledge of the identity or function of the target is necessary. The interaction between the ligand and target may be covalent or non-covalent. Optionally, the ligand of a ligand-target pair may or may not display affinity for other targets. The target of a ligand-target pair may or may not display affinity for other ligands.

For example, binding between a ligand and a target can be identified at the protein level using in vitro biochemical methods, including photo-crosslinking, radiolabeled ligand binding, and affinity chromatography (Jakoby WB et al., 1974, Methods in Enzymology 46: 1). Alternatively, small molecules can be immobilized on a suitable solid support or affinity matrix such as an agarose matrix and used to screen extracts of a variety of cell types and organisms. Similarly, the small molecules can be contacted with the cell, tissue, organ, organism or lysate or extract thereof and the solid support can be added later to retrieve the small molecules and associate target proteins.

Expression cloning can be used to test for the target within a small pool of proteins (King RW et. al., 1997, Science 277:973). Peptides (Kieffer et. al., 1992, PNAS 89: 12048), nucleoside derivatives (Haushalter KA et. al., 1999, Curr. Biol. 9:174), and drug-bovine serum albumin (drug-BSA) conjugate (Tanaka et. al., 1999, MoI. Pharmacol. 55:356) have been used in expression cloning.

Another useful technique to closely associate ligand binding with DNA encoding the target is phage display. In phage display, which has been predominantly used in the monoclonal antibody field, peptide or protein libraries are created on the viral surface and screened for activity (Smith GP, 1985, Science 228:1315). Phages are panned for the target which is connected to a solid phase (Parmley SF et al., 1988, Gene 73:305). One of the advantages of phage display is that the cDNA is in the phage and thus no separate cloning step is required.

A non-limiting example includes binding reaction conditions where the ligand comprises a marker such as biotin, fluorescein, digoxygenin, green fluorescent protein, radioisotope, histidine tag, a magnetic bead, an enzyme or combinations thereof. In one embodiment of the invention, the targets may be screened in a mechanism based assay, such as an assay to detect ligands which bind to the target. This may include a solid phase or fluid phase binding event with either the ligand or the protein or an indicator of either being detected. Alternatively, the gene encoding the protein with previously undefined function can be transfected with a reporter system {e.g., β-galactosidase, luciferase, or green fluorescent protein) into a cell and screened against the library preferably by a high throughput screening method or with individual members of the library. Other mechanism based binding assays may be used, for example, biochemical assays measuring an effect on enzymatic activity, cell based assays in which the target and a reporter system (e.g., luciferase.or β-galactosidase) have been introduced into a cell, and binding assays which detect changes in free energy. Binding assays can be performed with the target fixed to a well, bead or chip or captured by an immobilized antibody or resolved by capillary electrophoresis. The bound ligands may be detected usually using colorimetric or fluorescence or surface plasmon resonance.

In certain embodiments, the present invention further contemplates methods of treating or preventing a disease (e.g., cancer) by modulating the function (e.g., activity or expression) of a target (cellular component) that is identified according to the invention. To illustrate, if a target is identified to promote tumor growth, a therapeutic agent can be used to modify or reduce the function (activity or expression) of the target. Alternatively, if a target is identified to inhibit tumor growth, a therapeutic agent can be used to enhance the function (activity or expression) of the target. The therapeutic agent is a compound of the invention.

Erastin Targets

In certain embodiments, the present invention provides targets of compounds of the invention, which are generally referred to herein as erastin targets. The erastin targets may directly or indirectly bind to a compound of the invention as described above. Optionally, the erastin target may mediate the anti-tumor activity of a compound of the invention in a cell. Exemplary erastin targets include, but are not limited to, VDACl, VDAC2, VDAC3, Prohibitin, Ribophorin, Secδla, and Sec22b.

Voltage-dependent anion channels (VDACs) are a family of pore-forming proteins encoded by different genes, with at least three protein products (VDACl , VDAC2, and VDAC3) expressed in mammalian tissues. The major recognized functional role of VDACs is to permit the almost free permeability of the outer mitochondrial membrane (ODF). See, e.g., Shoshan-Barmatz et al., 2003, Cell Biochem Biophys 39:279-92. VDAC2 and VDAC3 might have an alternative structural organization and different functions in ODF than in mitochondria (Hinsch et al., 2004, J Biol Chem. 279:15281-8). Representative VDAC sequences of various species have been deposited in GenBank. For example, human VDACl amino acid and nucleic acid sequences can be found in GenBank Accession numbers

NP_003365 and 1MM_OO3374; human VDAC2 amino acid and nucleic acid sequences can be found in GenBank Accession numbers NP_003366 and NM_OO3375; and human VDAC3 amino acid and nucleic acid sequences can be found in GenBank Accession numbers NP_005653 and NM_005662.

Prohibitin is an evolutionarily conserved gene that is ubiquitously expressed. It is thought to be a negative regulator of cell proliferation and maybe a tumor suppressor (e.g., Fusaro et al., 2003, J. Biol. Chem. 278: 47853-47861; Fusaro et al., 2002, Oncogene 21 : 4539-4548). Representative prohibitin sequences of various species have been deposited in GenBank. For example, human prohibitin amino acid and nucleic acid sequences can be found in GenBank Accession numbers NP_002625 and NM_002634.

Ribophorins (e.g., I and II) are proteins that appear to be involved in ribosome binding. They are abundant, highly conserved glycoproteins located exclusively in the membranes of the rough endoplasmic reticulum (e.g., Fu et al., 2000, J. Biol. Chem. 275: 3984-3990; Crimaudo et al., 1987, EMBO J. 6: 75-82). Representative ribophorin sequences of various species have been deposited in GenBank. For example, human ribophorin I amino acid and nucleic acid sequences can be found in GenBank Accession numbers NP_002941 and NM_002950; and human ribophorin 11 amino acid and nucleic acid sequences can be found in GenBank Accession numbers NP_002942 and NMJ302951.

Secόl -alpha proteins are suggested to play a role in the insertion of secretory and membrane polypeptides into the endoplasmic reticulum (see, e.g., Higy et al., 2004, Biochemistry 43:12716-22). Representative Secόl alpha sequences of various species have been deposited in GenBank. For example, human Sec61 -alpha-I amino acid and nucleic acid sequences can be found in GenBank Accession numbers NP_037468 and NM_013336; and human Sec61-alpha-II amino acid and nucleic acid sequences can be found in GenBank Accession numbers NP_060614 and NM_018144.

Sec22-beta proteins are suggested to play a role in the ER-Golgi protein trafficking and complex with SNARE (e.g., Parlati et al., 2000, Nature 407:194-198; Mao et al., 1998, Proc. Natl. Acad. Sci. U.S.A. 95:8175-8180). Representative Secόl -beta sequences of various species have been deposited in GenBank. For example, human Secό l -beta amino acid and nucleic acid sequences can be found in GenBank Accession numbers NP_004883 and NM_004892. Delivery Methods

Certain embodiments of the invention use methods of delivering proteins (e.g., small t antigen, VDAC, PP2A inhibitors, etc.) or DNA encoding such proteins to a target cell, which can be accomplished by any standard molecular biology and molecular medicine techniques. The embodiments illustrated below are but a few such techniques that can be used for such purposes.

In one aspect of the invention, expression constructs of the subject proteins, or for generating antisense molecules, may be administered in any biologically effective carrier, e.g., any formulation or composition capable of effectively transfecting cells in vivo with a recombinant gene. Approaches include insertion of the subject gene in viral vectors including recombinant retroviruses, adenovirus, adeno-associated virus, and herpes simplex virus- 1, or recombinant bacterial or eukaryotic plasmids. Viral vectors can be used to transfect cells directly; plasmid DNA can be delivered with the help of, for example, cationic liposomes

(e.g., lipofectin) or derivatized (e.g., antibody conjugated), polylysine conjugates, gramacidin S, artificial viral envelopes or other such intracellular carriers, as well as direct injection of the gene construct or CaPO₄ precipitation carried out in vivo. It will be appreciated that because transduction of appropriate target cells represents the critical first step in gene therapy, choice of the particular gene delivery system will depend on such factors as the phenotype of the intended target and the route of administration, e.g., locally or systemically.

A preferred approach for in vivo introduction of nucleic acid encoding one of the subject proteins into a cell is by use of a viral vector containing a nucleic acid, e.g., a cDNA, encoding the gene product. Infection of cells with a viral vector has the advantage that a large proportion of the targeted cells can receive the nucleic acid. Additionally, molecules encoded within the viral vector, e.g., by a cDNA contained in the viral vector, are expressed efficiently in cells which have taken up viral vector nucleic acid.

Retroviral vectors and adeno-associated viral vectors are generally understood to be the recombinant gene delivery systems of choice for the transfer of exogenous genes in vivo, particularly into humans. These vectors provide efficient delivery of genes into cells, and the transferred nucleic acids are stably integrated into the chromosomal DNA of the host. A subset of the retrovirus family termed "lentiviruses" for the long duration of their latent phases following integration, are represented by the human immunodeficiency virus (HlV) and the feline immunodeficiency virus (FlV). Vector systems derived from both of these viruses have been used effectively in pre-clinical models and show great promise for therapeutic application (Humeau et al., MoI Ther. 2004, 9(6):902-13; Curran et al., MoI Ther. 2000, 1( 1):31-8; Engel and Kohn, Front Biosci. 199, 4:e26-33). Unlike most retroviruses, HIV and FlV (and vectors derived from them) have the ability to transduce non-dividing cells (Humeau et al., MoI Ther. 2004, 9(6):902-13; Curran et al., MoI Ther. 2000, l(l):31-8). This property may be advantageous depending upon the target cell type. In addition, FlV may distinguish itself from other retroviruses by its increased transgene carrying capacity (Curran et al., MoI Ther. 2000, l(l):31-8). A major prerequisite for the use of retroviruses is to ensure the safety of their use, particularly with regard to the possibility of the spread of wild- type virus in the cell population. The development of specialized cell lines (termed "packaging cells") which produce only replication-defective retroviruses has increased the utility of retroviruses for gene therapy, and defective retroviruses are well characterized for use in gene transfer for gene therapy purposes (for a review see Miller, A.D., Blood 76:271 , 1990). Thus, recombinant retrovirus can be constructed in which part of the -retroviral coding sequence (gag, pol, env) has been replaced by nucleic acid encoding a subject polypeptide, ' rendering the retrovirus replication-defective. The replication-defective retrovirus is then packaged into virions which can be used to infect a target cell through the use of a helper virus by standard techniques. Protocols for producing recombinant retroviruses and for infecting cells in vitro or in vivo with such viruses can be found in Current Protocols in

Molecular Biology, Ausubel, F.M. et al., (eds.), John Wiley & Sons, Inc., Greene Publishing Associates, (2001), Sections 9.9-9.14 and other standard laboratory manuals. Examples of suitable retroviruses include pLJ, pZIP, pWE and pEM which are well known to those skilled in the art. Examples of suitable packaging virus lines for preparing both ecotropic and amphotropic retroviral systems include ψCrip, ψCre,

and ψAm. Retroviruses have been used to introduce a variety of genes into many different cell types, including neural cells, epithelial cells, endothelial cells, lymphocytes, myoblasts, hepatocytes, bone marrow cells, in vitro and/or in vivo (see, for example, Eglitis et al., Science 230:1395-1398, 1985; Danos and Mulligan, PNAS USA 85:6460-6464, 1988; Wilson et al., PNAS USA 85:3014-3018, 1988; Armentano et al., PNAS USA 87:6141 -6145, 1990; Ruber et al., PNAS USA 88:8039-8043, 1991 ; Ferry et al., PNAS USA 88:8377-8381, 1991; Chowdhiiry el al., Science 254:1802- 1805, 1991 ; van Beusechem et al., PNAS USA 89:7640-7644, 1992; Kay et al., Human Gene Therapy 3.-641-647, 1992; Dai et al., PNAS USA 89:10892-10895, 1992; Hwu et al., J. Immunol. 150:4104-41 15, 1993; U.S. Patent No. 4,868,1 16; U.S. Patent NO: 4,980,286; PCT Application WO 89/07136; PCT Application WO 89/02468; PCT Application WO 89/05345; and PCT Application WO 92/07573).

Furthermore, it has been shown that it is possible to limit the infection spectrum of retroviruses and consequently of retroviral-based vectors, by modifying the viral packaging proteins on the surface of the viral particle (see, for example, PCT publications WO 93/25234, WO 94/06920, and WO 94/11524). For instance, strategies for the modification of the infection spectrum of retroviral vectors include coupling antibodies specific for cell surface antigens to the viral env protein (Roux et al, PNAS USA 86:9079-9083, 1989; Julan et al, J. Gen Virol 73:3251-3255, 1992; and Goud et al., Virology 163:251-254, 1983); or coupling cell surface ligands to the viral env proteins (Neda et al., J. Biol. Chem. 266:14143- 14146, 1991). Coupling can be in the form of the chemical cross-linking with a protein or other variety (e.g., lactose to convert the env protein to an asialoglycoprotein), as well as by generating fusion proteins (e.g., single-chain antibody/env fusion proteins). This technique, while useful to limit or otherwise direct the infection to certain tissue types, can also be used to convert an ecotropic vector into an ampho tropic vector.

Another viral gene delivery system useful in the present invention utilizes adenovirus- derived vectors. The genome of an adenovirus can be manipulated such that it encodes a gene product of interest, but is inactive in terms of its ability to replicate in a normal lytic viral life cycle (see, for example, Berkner et al., BioTechniques 6:616, 1988; Rosenfeld et al., Science 252:431-434, 1991 ; and Rosenfeld et al, Cell 68:143-155, 1992). Suitable adenoviral vectors derived from the adenovirus strain Ad type 5 d!324 or other strains of adenovirus (e.g. , Ad2, Ad3, Ad7 etc.) are well known to those skilled in the art. Recombinant adenoviruses can be advantageous in certain circumstances in that they are not capable of infecting nondividing cells and can be used to infect a wide variety of cell types, including airway epithelium (Rosenfeld et al, (1992) cited j-«/?rø), endothelial cells (Lemarchand et al, PNAS USA 89:6482-6486, 1992), hepatocytes (Herz and Gerard, PNAS USA 90:2812-2816, 1993) and muscle cells (Quantin et al, PNAS USA 89:2581 -2584, 1992). Furthermore, the virus particle is relatively stable, amenable to purification and concentration, and as described above, can be modified to affect the spectrum of infectivity. Additionally, introduced adenoviral DNA (and foreign DNA contained therein) is not integrated into the genome of a host cell but remains episomal, thereby avoiding potential problems that can occur as a result of insertional mutagenesis in situations where introduced DNA becomes integrated into the host genome (e.g., retroviral DNA). Moreover, the carrying capacity of the adenoviral genome for foreign DNA is large (up to 8 kilobases) relative to other gene delivery vectors (Berkner et al, supra; Haj-Ahmand and Graham J., Virol. 57:267, 1986). Most replication- defective adenoviral vectors currently in use and therefore favored by the present invention are deleted for all or parts of the viral El and E3 genes but retain as much as 80% of the adenoviral genetic material (see, e.g., Jones et al, Cell 16:683, 1979; Berkner et al, supra; and Graham et al, in Methods in Molecular Biology, EJ. Murray, Ed. (Humana, Clifton, NJ, 1991) vol. 7. pp. 109-127). Expression of the inserted subject gene can be under control of, for example, the El A promoter, the major late promoter (MLP) and associated leader sequences, the viral E3 promoter, or exogenously added promoter sequences.

Yet another viral vector system useful for delivery of the subject genes is the adeno- associated virus (AAV). Adeno-associated virus is a naturally occurring defective virus that requires another virus, such as an adenovirus or a herpes virus, as a helper virus for efficient replication and a productive life cycle. (For a review, see Muzyczka et al., Curr. Topics in Micro. Immunol. (1992) 158:97-129, 1992.) It is also one of the few viruses that may integrate its DNA into non-dividing cells, and exhibits a high frequency of stable integration (see for example Flotte et al., Am. J. Respir. Cell. MoI. Biol. 7:349-356, 1992; Samulski et al., L Virol. 63:3822-3828, 1989; and McLaughlin et al, J. Virol. 62:1963-1973, 1989). Vectors containing as few as 300 base pairs of AAV can be packaged and can integrate. Space for exogenous DNA is limited to about 4.5 kb. An AAV vector such as that described in Tratschin et al., MoI. Cell. Biol. 5:3251-3260, 1985 can be used to introduce DNA into cells. A variety of nucleic acids have been introduced into different cell types using AAV vectors (see for example Hermonat et al., PNAS USA 81.6466-6470, 1984; Tratschin et al., MoI. Cell. Biol. 4:2072-2081, 1985; Wondisford et al., MoI. Endocrinol. 2:32-39, 1988; Tratschin et al, J. Virol. 51 :61 1-619, 1984; and Flotte et al, J. Biol. Chem. 268:3781-3790, 1993).

Other viral vector systems that may have application in gene therapy have been derived from herpes virus, vaccinia virus, and several RNA viruses. In particular, herpes virus vectors may provide a unique strategy for persistence of the subject recombinant gene in cells of the central nervous system and ocular tissue (Pepose et al, Invest Ophthalmol Vis Sci 35:2662-2666, 1994).

In addition to viral transfer methods, such as those illustrated above, non-viral methods can also be employed to cause expression of a subject protein in the tissue of an animal. Most nonviral methods of gene transfer rely on normal mechanisms used by mammalian cells for the uptake and intracellular transport of macromolecules. In preferred embodiments, non- viral gene delivery systems of the present invention rely on cndocytic pathways for the uptake of the subject gene by the targeted cell. Exemplary gene delivery systems of this type include liposomal derived systems, poly-lysine conjugates, and artificial viral envelopes.

In a representative embodiment, a gene encoding a subject polypeptide can be entrapped in liposomes bearing positive charges on their surface {e.g., lipofectins) and (optionally) which are tagged with antibodies against cell surface antigens of the target tissue (Mizuno et al., No Shinkei Geka 20:547-551,1992; PCT publication WO 91/06309; Japanese patent application 1047381; and European patent publication EP-A-43075). For example, lipofection of neuroglioma cells can be carried out using liposomes tagged with monoclonal antibodies against glioma-associated antigen (Mizuno et al., Neurol. Med. Chir. 32:873-876, 1992).

In yet another illustrative embodiment, the gene delivery system comprises an antibody or cell surface ligand which is cross-linked with a gene binding agent such as poly- lysine (see, for example, PCT publications WO 93/04701, WO 92/22635, WO 92/20316, WO 92/19749, and WO 92/06180). For example, the subject gene construct can be used to transfect specific cells in vivo using a soluble polynucleotide carrier comprising an antibody conjugated to a poly-cation, e.g., poly-lysine (see U.S. Patent 5,166,320). It will also be appreciated that effective delivery of the subject nucleic acid constructs via peptide-mediated endocytosis can be improved using agents which enhance escape of the gene from the endosomal structures. For instance, whole adenovirus or fusogenic peptides of the influenza HA gene product can be used as part of the delivery system to induce efficient disruption of DNA-containing endosomes (Mulligan et al., Science 260-926, 1993; Wagner et al., PNAS USA 89:7934, 1992; and Christiano et al, PNAS USA 90:2122, 1993).

In clinical settings, the gene delivery systems can be introduced into a patient by any of a number of methods, each of which is familiar in the art. For instance, a pharmaceutical preparation of the gene delivery system can be introduced systemically, e.g., by intravenous injection, and specific transduction of the construct in the target cells occurs predominantly from specificity of transfection provided by the gene delivery vehicle, cell-type or tissue-type expression due to the transcriptional regulatory sequences controlling expression of the gene, or a combination thereof. In other embodiments, initial delivery of the recombinant gene is more limited with introduction into the animal being quite localized. For example, the gene delivery vehicle can be introduced by catheter (see U.S. Patent 5,328,470) or by stereotactic injection {e.g., Chen et al., PNAS USA 91 : 3054-3057, 1994). In addition, the subject proteins can be provided as a fusion peptide along with a second peptide which promotes "transcytosis", e.g., uptake of the peptide by target cells. To illustrate, the subject protein can be provided as part of a fusion polypeptide with all or a fragment of the N-terminal domain of the HIV protein Tat, e.g., residues 1-72 of Tat or a smaller fragment thereof which can promote transcytosis. In other embodiments, the subject polypeptide can be provided as a fusion polypeptide with all or a portion of the antennapedia III protein. Synthetic peptides have also been effectively used to transport proteins, peptides and small molecules across biological membranes including the blood brain barrier and therefore, may be applicable to this application. (Rothbard et al., Nat Med. 2000, 6(11):1253- 7; Rothbard et al., J Med Chem. 2002, 45(17):3612-8). While the synthetic protein transduction sequence examples provided are characterized by a high density of arginine residues, other functionally similar but structurally dissimilar molecules or sequences could be substituted.

To further illustrate, the subject polypeptide (or peptidomimetic) can be provided as a chimeric peptide which includes a heterologous peptide sequence ("internalizing peptide" or "internalization domain") which drives the translocation of an extracellular form of a subject polypeptide sequence across a cell membrane in order to facilitate intracellular localization of the subject polypeptide. In this regard, the therapeutic subject polypeptide is one which is active intracellularly. The internalizing peptide, by itself, is capable of crossing a cellular membrane by, e.g., transcytosis, at a relatively high rate. The internalizing peptide is conjugated, e.g., as a fusion protein, to the subject polypeptide, optionally in a cleavable manner. The resulting chimeric peptide is transported into cells at a higher rate relative to the activator polypeptide alone, thereby providing a means for enhancing its introduction into cells to which it is applied, e.g., to enhance topical applications of the subject polypeptide. In addition to proteins and peptidomimetics, an agent of the drug can be coupled to a compound that enhances delivery to a substance (e.g., receptor-mediated compounds such as Vitamin B₁₂).

In one embodiment, the internalizing peptide is derived from the Drosophila antennapedia protein, or homologs thereof. The 60 amino acid long homeodomain of the homeo-protein antennapedia has been demonstrated to translocate through biological membranes and can facilitate the translocation of heterologous polypeptides to which it is coupled. See, for example, Derossi et al. (1994) J Biol Chem 269: 10444- 10450; and Perez et al. (1992) J Cell Sci 102:717-722. It has been demonstrated that fragments as small as 16 amino acids long of this protein arc sufficient to drive internalization. See Derossi et al. (1996) J Biol Chem 271 :18188-18193.

The present invention also provides a polypeptide (small t antigen or VDAC) or peptidomimetic sequence as described herein, and at least a portion of the Antennapedia protein (or homo log thereof) sufficient to increase the transmembrane transport of the chimeric protein, relative to the subject polypeptide or peptidomimetic, by a statistically significant amount. Such polypeptide or peptidomimetic thereof may be used in the subject methods to assist in efficient and specific killing of cancer cells.

Another example of an internalizing peptide is the HIV transactivator (TAT) protein. This protein appears to be divided into four domains (Kuppuswamy et a (1989) Nucl. Acids Res. 17:3551-3561). Purified TAT protein is taken up by cells in tissue culture (Frankel and Pabo, (1989) Cell 55:1189-1193), and peptides, such as the fragment corresponding to residues 37-62 of TAT, are rapidly taken up by cell in vitro (Green and Loewenstein, (1989) Cell 55: 1179-1188). The highly basic region mediates internalization and targeting of the internalizing moiety to the nucleus (Ruben et al., (1989) J. Virol. 63:1-8).

Another exemplary transcellular polypeptide can be generated to include a sufficient portion of mastoparan (T. Higashijima et al., (1990) J. Biol. Chem. 265:14176) to increase the transmembrane transport of the chimeric protein.

While not wishing to be bound by any particular theory, it is noted that hydrophilic polypeptides may be also be physiologically transported across the membrane barriers by coupling or conjugating the polypeptide to a transportable peptide which is capable of crossing the membrane by receptor-mediated transcytosis. Suitable internalizing peptides of this type can be generated using all or a portion of, e.g., a histone, insulin, transferrin, basic albumin, prolactin and insulin-like growth factor I (IGF-I), insulin-like growth factor II (IGF- II) or other growth factors. For instance, it has been found that an insulin fragment, showing affinity for the insulin receptor on capillary cells, and being less effective than insulin in blood sugar reduction, is capable of transmembrane transport by receptor-mediated transcytosis and can therefore serve as an internalizing peptide for the subject transcellular peptides and peptidomimetics. Preferred growth factor-derived internalizing peptides include EGF (epidermal growth factor)-derived peptides, such as CMHIESLDSYTC and

CMY1EALDKYAC; TGF-beta (transforming growth factor beta)-derived peptides; peptides derived from PDGF (platelet-derived growth factor) or PDGF-2; peptides derived from IGF-I (insulin-like growth factor) or IGF-II; and FGF (fibroblast growth factor)-derived peptides. Another class of translocating/internalizing peptides exhibits pH-dependent membrane binding. For an internalizing peptide that assumes a helical conformation at an acidic pH, the internalizing peptide acquires the property of amphiphilicity, e.g., it has both hydrophobic and hydrophilic interfaces. More specifically, within a pH range of approximately 5.0-5.5, an internalizing peptide forms an alpha-helical, amphophilic structure that facilitates insertion of the moiety into a target membrane. An alpha-helix-inducing acidic pH environment may be found, for example, in the low pH environment present within cellular endosomes. Such internalizing peptides can be used to facilitate transport of subject polypeptide and peptidomimetics, taken up by an endocytic mechanism, from endosomal compartments to the cytoplasm.

A preferred pH-dependent membrane-binding internalizing peptide includes a high percentage of helix-forming residues, such as glutamate, methionine, alanine and leucine. In addition, a preferred internalizing peptide sequence includes ionizable residues having pKa's within the range of pH 5-7, so that a sufficient uncharged membrane-binding domain will be present within the peptide at pH 5 to allow insertion into the target cell membrane.

A particularly preferred pH-dependent membrane-binding internalizing peptide in this regard is aal-aa2-aa3-EAALA(EALA)4-EALEALAA-amide, which represents a modification of the peptide sequence of Subbarao et al. (Biochemistry 26:2964, 1987). Within this peptide sequence, the first amino acid residue (aal) is preferably a unique residue, such as cysteine or lysine, that facilitates chemical conjugation of the internalizing peptide to a targeting protein conjugate. Amino acid residues 2-3 may be selected to modulate the affinity of the internalizing peptide for different membranes. For instance, if both residues 2 and 3 are lys or arg, the internalizing peptide will have the capacity to bind to membranes or patches of lipids having a negative surface charge. If residues 2-3 are neutral amino acids, the internalizing peptide will insert into neutral membranes.

Yet other preferred internalizing peptides include peptides of apo-lipoprotein A-I and B; peptide toxins, such as melittin, bombolittin, delta hemolysin and the pardaxins; antibiotic peptides, such as alamethicin; peptide hormones, such as calcitonin, corticotrophin releasing factor, beta endorphin, glucagon, parathyroid hormone, pancreatic polypeptide; and peptides corresponding to signal sequences of numerous secreted proteins. In addition, exemplary internalizing peptides may be modified through attachment of substituents that enhance the alpha-helical character of the. internalizing peptide at acidic pH. Yet another class of internalizing peptides suitable for use within the present invention includes hydrophobic domains that are "hidden" at physiological pH, but are exposed in the low pH environment of the target cell endosome. Upon pH-induced unfolding and exposure of the hydrophobic domain, the moiety binds to lipid bilayers and effects translocation of the covalently linked polypeptide into the cell cytoplasm. Such internalizing peptides may be modeled after sequences identified in, e.g., Pseudomonas exotoxin A, clathrin, or Diphtheria toxin.

Pore-forming proteins or peptides may also serve as internalizing peptides herein. Pore- forming proteins or peptides may be obtained or derived from, for example, C9 complement protein, cytolytic T-cell molecules or NK-cell molecules. These moieties are capable of forming ring-like structures in membranes, thereby allowing transport of attached polypeptide through the membrane and into the cell interior.

Mere membrane intercalation of an internalizing peptide may be sufficient for translocation of the subject polypeptide or peptidomimetic, across cell membranes. However, translocation may be improved by attaching to the internalizing peptide a substrate for intracellular enzymes (i.e., an "accessory peptide"). It is preferred that an accessory peptide be attached to a portion(s) of the internalizing peptide that protrudes through the cell membrane to the cytoplasmic face. The accessory peptide may be advantageously attached to one terminus of a translocating/internalizing moiety or anchoring peptide. An accessory moiety of the present invention may contain one or more amino acid residues. In one embodiment, an accessory moiety may provide a substrate for cellular phosphorylation (for instance, the accessory peptide may contain a tyrosine residue).

An exemplary accessory moiety in this regard would be a peptide substrate for N- myristoyl transferase, such as GNAAAARR (Eubanks et al., in: Peptides. Chemistry and . Biology, Garland Marshall (ed.), ESCOM, Leiden, 1988, pp. 566-69). In this construct, an internalizing peptide would be attached to the C-terminus of the accessory peptide, since the N-terminal glycine is critical for the accessory moiety's activity. This hybrid peptide, upon attachment to an E2 peptide or peptidomimetic at its C-terminus, is N-rnyristylated and further anchored to the target cell membrane, e.g., it serves to increase the local concentration of the peptide at the cell membrane.

To further illustrate use of an accessory peptide, a phosphorylatable accessory peptide is first covalently attached to the C-terminus of an internalizing peptide and then incorporated into a fusion protein with a subject polypeptide or peptidomimetic. The peptide component of the fusion protein intercalates into the target cell plasma membrane and, as a result, the accessory peptide is translocated across the membrane and protrudes into the cytoplasm of the target cell. On the cytoplasmic side of the plasma membrane, the accessory peptide is phosphorylated by cellular kinases at neutral pH. Once phosphorylated, the accessory peptide acts to irreversibly anchor the fusion protein into the membrane. Localization to the cell surface membrane can enhance the translocation of the polypeptide into the cell cytoplasm. Suitable accessory peptides include peptides that are kinase substrates, peptides that possess a single positive charge, and peptides that contain sequences which are glycosylated by membrane-bound glycotransferases. Accessory peptides that are glycosylated by membrane-bound glycotransferases may include the sequence x-NLT-x, where "x" may be another peptide, an amino acid, coupling agent or hydrophobic molecule, for example. When this hydrophobic tripeptide is incubated with microsomal vesicles, it crosses vesicular membranes, is glycosylated on the luminal side, and is entrapped within the vesicles due to its hydrophilicity (C. Hirschberg et al., (1987) Ann. Rev. Biochem. 56:63-87). Accessory peptides that contain the sequence x-NLT-x thus will enhance target cell retention of corresponding polypeptide.

In another embodiment of this aspect of the invention, an accessory peptide can be used to enhance interaction of a polypeptide or peptidomimetic with the target cell. Exemplary accessory peptides in this regard include peptides derived from cell adhesion proteins containing the sequence "RGD", or peptides derived from laminin containing the sequence CDPGYIGSRC. Extracellular matrix glycoproteins, such as fϊbronectin and laminin, bind to cell surfaces through receptor-mediated processes. A tripeptide sequence, RGD, has been identified as necessary for binding to cell surface receptors. This sequence is present in fibronectin, vitronectin, C3bi of complement, von-Willebrand factor, EGF receptor, transforming growth factor beta, collagen type 1, lambda receptor of E. CoIi, fibrinogen and Sindbis coat protein (E. Ruoslahti, Ann. Rev. Biochem. 57:375-413, 1988). Cell surface receptors that recognize RGD sequences have been grouped into a superfamily of related proteins designated "integrins". Binding of "RGD peptides" to cell surface integrins will promote cell-surface retention, and ultimately translocation, of the polypeptide. As described above, the internalizing and accessory peptides can each, independently, be added to the polypeptide or peptidomimetic by either chemical cross-linking or in the form of a fusion protein. In the instance of fusion proteins, unstructured polypeptide linkers can be included between each of the peptide moieties. In general, the internalization peptide will be sufficient for the direct export of the ^■ polypeptide. However, where an accessory peptide is provided, such as an RGD sequence, it may be necessary to include a secretion signal sequence to direct export of the fusion protein from its host cell. In preferred embodiments, the secretion signal sequence is located at the extreme N-terminus, and is (optionally) flanked by a proteolytic site between the secretion signal and the rest of the fusion protein.

In an exemplary embodiment, a polypeptide or peptidomimetic is engineered to include an integrin-binding RGD peptide/SV40 nuclear localization signal (see, for example Hart S L et al., 1994; J. Biol. Chem.,269: 12468-12474), such as encoded by the nucleotide sequence provided in the Ndel-EcoRl fragment: catatggutgactgccgtggcgatatgttcggttgcggtgctcctccaaaaaagaagagaaaggtagctggattc, which encodes the RGD/SV40 nucleotide sequence: MGGCRGDMFGCGAPPKKKRKVAGF. In another embodiment, the protein can be engineered with the HIV-I tat(l-72) polypeptide, e.g., as provided by the Ndel-EcoRl fragment: catatggagccagtagatcctagactagagccc- tggaagcatccaggaagtcagcctaaaactgcttgtaccaattgctattgtaaaaagtgttgctttcattgccaagtgtttc ataacaaaagcccttggcatctcctatggcaggaagaagcgagacagcgacgaagacctcctcaaggcagtcagact catcaagtttctctaagtaagcaaggattc, which encodes the HIV-I tat(l-72) peptide sequence: MEPVDPRLEPWKHPGSQPKTACTNCYCKKCCFHCQVCFITKALGISYGRKK RRQRRRPPQGSQTHQVSLSKQ. In still another embodiment, the fusion protein includes the HSV-I VP22 polypeptide (Elliott G., O'Hare P (1997) Cell, 88:223-233) provided by the Ndel-EcoRl fragment. In still another embodiment, the fusion protein includes the C- terminal domain of the VP22 protein from, e.g., the nucleotide sequence (Ndel-EcoRl fragment).

In certain instances, it may also be desirable to include a nuclear localization signal as part of a polypeptide. In the generation of fusion polypeptides including the subject polypeptide, it may be necessary to include unstructured linkers in order to ensure proper folding of the various peptide domains. Many synthetic and natural linkers are known in the art and can be adapted for use in the present invention, including the (Gly₃Ser)₄ linker.

Methods of Treatment

In certain embodiments, the invention provides a method to treat or prevent cancer in an individual. The terms "cancer," "tumor," and "neoplasia" are used interchangeably herein. As used herein, a cancer (tumor or neoplasia) is characterized by one or more of the following properties: cell growth is not regulated by the normal biochemical and physical . influences in the environment; anaplasia (e.g., lack of normal coordinated cell differentiation); and in some instances, metastasis. Cancer diseases include, for example,- anal carcinoma, bladder carcinoma, breast carcinoma, cervix carcinoma, chronic lymphocytic leukemia, chronic myelogenous leukemia, endometrial carcinoma, hairy cell leukemia, head and neck carcinoma, lung (small cell) carcinoma, multiple myeloma, non-Hodgkin's lymphoma, follicular lymphoma, ovarian carcinoma, brain tumors, colorectal carcinoma, hepatocellular carcinoma, Kaposi's sarcoma, lung (non-small cell carcinoma), melanoma, pancreatic carcinoma, prostate carcinoma, renal cell carcinoma, and soft tissue sarcoma.

Additional cancer disorders can be found in, for example, Isselbacher et al. (1994) Harrison's Principles of Internal Medicine 1814-1877, herein incorporated by reference.

Typically, the cancers described above and treatable by the methods described herein exhibit deregulated VDAC expression. In one embodiment, the cancers described above contain a mutation in the Ras signaling pathway, resulting in elevated Ras signaling activity. For example, the mutation could be a constitutively active mutation in the Ras gene, such as Ras V 12. In other embodiments, the cancer may contain loss of function mutations in PP2A, and/or activating mutations of MEKl and/or ERKl . In certain further embodiments, the cancer is characterized by cells expressing SV40 small T oncoprotein, or are phenotypically similar to cells expressing ST, and/or oncogenic HRAS. In certain preferred embodiments, the cells express substantially wild-type level of Rb (e.g., at least about 50%, 60%, 70%, 80%, 90%, 100%, 1 10%, 120%, 130%, or 150%, etc.)

In one embodiment, the invention relates to a method of treating or preventing cancer in an individual, comprising administering to the individual a therapeutically effective amount of a compound that is selectively toxic to an engineered human tumorigenic cell, or a cancer cell of specific genotype (or specifically altered genotype). In certain embodiments, the cancer is characterized by cells comprising an activated RAS pathway. In certain further embodiments, the cancer is characterized by cells expressing SV40 small T oncoprotein, or exhibiting modulations of targets of sT and/or oncogenic RAS. In a related embodiment, the invention contemplates the practice of the method of the invention in conjunction with other anti-tumor therapies such as conventional chemotherapy directed against solid tumors and for control of establishment of metastases. The administration of the other anti-tumor therapies can be conducted during or after chemotherapy. Such agents are typically formulated with a pharmaceutically acceptable carrier, and can be administered intravenously, orally, bucally, parenterally, by an inhalation spray, by topical application or transdermally. An agent can also be administered by local administration. Preferably, one or more additional agents administered in conjunction with an anti-cancer chemotherapeutic agent (e.g., a compound of the invention) inhibits cancer cells in an additive or synergistic manner compare.

A wide array of conventional compounds has been shown to have anti-tumor activities. These compounds have been used as pharmaceutical agents in chemotherapy to shrink solid tumors, prevent metastases and further growth, or decrease the number of malignant cells in leukemic or bone marrow malignancies. Although chemotherapy has been effective in treating various types of malignancies, many anti-tumor compounds induce undesirable side effects. In many cases, when two or more different treatments are combined, the treatments may work synergistically and allow reduction of dosage of each of the treatments, thereby reducing the detrimental side effects exerted by each compound at higher dosages. In other instances, malignancies that are refractory to a treatment may respond to a combination therapy of two or more different treatments.

Therefore, compounds and pharmaceutical compositions of the present invention may be conjointly administered with a conventional anti-tumor compound. Conventional antitumor compounds include, merely to illustrate: aminoglutethimide, amsacrine, anastrozole, asparaginase; beg, bicalutamide, bleomycin, buserelin, busulfan, camptothecin, capecitabine, carboplatin, carmustine, chlorambucil, cisplatin, cladribine, clodronate, colchicine, cyclophosphamide, cyproterone, cytarabine, dacarbazine, dactinomycin, daunorubicin, dienestrol, diethylstilbestrol, docetaxel, doxorubicin, epirubicin, estradiol, estramustine, etoposide, exemestane, filgrastim, fludarabine, fludrocortisone, fluorouracil, fluoxymesterone, flutamide, gemcitabine, genistein, goserelin, hydroxyurea, idarubicin, ifosfamide, imatinib, interferon, irinotecan, ironotecan, letrozole, leucovorin, leuprolide, levamisole, lomustine, mechlorethamine, medroxyprogesterone, megestrol, melphalan, mercaptopurine, mesna, methotrexate, mitomycin, mitotane, mitoxantrone, nilutamide, nocodazole, octreotide, oxaliplatin, paclitaxel, pamidronate, pentostatin, plicamycin, porfimer, procarbazine, raltitrexed, rituximab, streptozocin, suramin, tamoxifen, temozolomide, teniposide, testosterone, thioguanine, thiotepa, titanocene dichloride, topotecan, trastuzumab, tretinoin, vinblastine, vincristine, vindesine, and vinorelbine. In other embodiments, compounds and pharmaceutical compositions of the present invention may be conjointly administered with a conventional anti-tumor compound selected from: an EGF-receptor antagonist, arsenic sulfide, adriamycin, cisplatin, carboplatin, cimetidine, carminomycin, mechlorethamine hydrochloride, pentamethylmel amine, thiotepa, teniposide, cyclophosphamide, chlorambucil, demethoxyhypocrellin A₃ -melphalan, ifosfamide, trofosfamide, Treosulfan, podophyllotoxin or podophyllotoxin derivatives, etoposide phosphate, teniposide, etoposide, leurosidine, leurosine, vindesine, 9- aminocamptothecin, camptoirinotecan, crisnatol, megestrol, methopterin, mitomycin C, ecteinascidin 743, busulfan, carmustine (BCNU), lomustine (CCNU), lovastatin, 1 -methyl -4- phenylpyridinium ion, semustine, staurosporine, streptozocin, phthalocyanine, dacarbazine, aminopterin, methotrexate, trimetrexate, thioguanine, mercaptopurine, fludarabine, pentastatin, cladribin, cytarabine (ara C), porfiromycin, 5-fluorouracil, 6-mercaptopurine, doxorubicin hydrochloride, leucovorin, mycophenolic acid, daunorubicin, deferoxamine, floxuridine, doxifluridine, raltitrexed, idarubicin, epirubican, pirarubican, zorubicin, mitoxantrone, bleomycin sulfate, actinomycin D₅ safracins, saframycins, quinocarcins, discodermolides, vincristine, vinblastine, vinorelbine tartrate, vcrtoporfin, paclitaxel, tamoxifen, raloxifene, tiazofuran, thioguanine, ribavirin, EICAR, estramustine, estramustine phosphate sodium, flutamide, bicalutamide, buserelin, leuprolide, pteridines, enediynes, levamisole, aflacon, interferon, interleukins, aldesleukin, filgrastim, sargramostim, rituximab, BCG, tretinoin, betamethasone, gemcitabine hydrochloride, verapamil, VP-16, altretamine, thapsigargin, oxaliplatin, iproplatin, tetraplatin, lobaplatin, DCP, PLD-147, JMl 18, JM216, JM335, satraplatin, docetaxel, deoxygenated paclitaxel, TL- 139, 5 '-nor-anhydro vinblastine (hereinafter: 5'-nor- vinblastine), camptothecin, irinotecan (Camptosar, CPT-I l), topotecan (Hycamptin), BAY 38-3441, 9-nitrocamptothecin (Orethecin, rubitecan), exatecan (DX- 8951 ), lurtotecan (GI-14721 1C), gimatecan, homocamptothecins diflomotecan (BN-80915) and 9-aminocamptothecin (IDEC- 13'), SN-38, STl 481, karanitecin (BNP 1350), indolocarbazoles (e.g., NB-506), protoberberines, intoplicines, idenoisoquinolones, benzo- phenazines or NB-506.

In another related embodiment, the invention contemplates the practice of the method in conjunction with other anti-tumor therapies such as radiation. As used herein, the term "radiation" is intended to include any treatment of a neoplastic cell or subject by photons, neutrons, electrons, or other type of ionizing radiation. Such radiations include, but are not limited to, X-ray, gamma-radiation, or heavy ion particles, such as alpha or beta particles. Additionally, the radiation may be radioactive. The means for irradiating neoplastic cells in a subject are well known in the art and include, for example, external beam therapy, and brachytherapy.

Methods to determine if a cancer (tumor or neoplasia) has been treated are well known to those skilled in the art and include, for example, a decrease in the number of tumor cells (e.g., a decrease in cell proliferation or a decrease in tumor size). Tt is recognized that the treatment of the present invention may be a lasting and complete response or can encompass a partial or transient clinical response. See for example, lsselbacher et al. (1996) Harrison's Principles of Internal Medicine 13 ed., 1814-1882, incorporated herein by reference.

Assays to test for the sensitization or the enhanced death of tumor cells are well known in the art, including, for example, standard dose response assays that assess cell viability; agarose gel electrophoresis of DNA extractions or flow cytometry to determine DNA fragmentation, a characteristic of cell death; assays that measure the activity of polypeptides involved in apoptosis; and assay for morphological signs of cell death. The details regarding such assays are described elsewhere herein. Other assays include, chromatin assays (e.g., counting the frequency of condensed nuclear chromatin) or drug resistance assays as described in, for example, Lowe et al. (1993) Cell 74:95 7-697, herein incorporated by reference. See also U.S. Patent No. 5,821,072, also herein incorporated by reference. Pharmaceutical Compositions

Prospective therapeutic agents can be profiled in order to determine their suitability for inclusion in a pharmaceutical composition. One common measure for such agents is the therapeutic index, which is the ratio of the therapeutic dose to a toxic dose. The thresholds for therapeutic dose (efficacy) and toxic dose can be adjusted as appropriate (e.g., the necessity of a therapeutic response or the need to minimize a toxic response). For example, a therapeutic dose can be the therapeutically effective amount of an agent (relative to treating one or more conditions) and a toxic dose can be a dose that causes death (e.g., an LD₅₀) or causes an undesired effect in a proportion of the treated population. Preferably, the therapeutic index of an agent is at least 2, more preferably at least 5, and even more preferably at least 10. Profiling a therapeutic agent can also include measuring the pharmacokinetics of the agent, to determine its bioavailability and/or absorption when administered in various formulations and/or via various routes. A compound of the present invention can be administered to an individual in need thereof. In certain embodiments, the individual is a mammal such as a human, or a non- human mammal. When administered to an individual, the compound of the invention can be administered as a pharmaceutical composition containing, for example, the compound of the invention and a pharmaceutically acceptable carrier. Pharmaceutically acceptable carriers are well known in the art and include, for example, aqueous solutions such as water or physiologically buffered saline or other solvents or vehicles such as glycols, glycerol, oils such as olive oil or injectable organic esters. In a preferred embodiment, when such pharmaceutical compositions are for human administration, the aqueous solution is pyrogen free, or substantially pyrogen free. The excipients can be chosen, for example, to effect delayed release of an agent or to selectively target one or more cells, tissues or organs.

A pharmaceutically acceptable carrier can contain physiologically acceptable agents that act, for example, to stabilize or to increase the absorption of a compound of the invention. Such physiologically acceptable agents include, for example, carbohydrates, such as glucose, sucrose or dextrans, antioxidants, such as ascorbic acid or glutathione, chelating agents, low molecular weight proteins or other stabilizers or excipients. The choice of a pharmaceutically acceptable carrier, including a physiologically acceptable agent, depends, for example, on the route of administration of the composition. The pharmaceutical composition (preparation) also can be a liposome or other polymer matrix, which can have incorporated therein, for example, a compound of the invention. Liposomes, for example, which consist of phospholipids or other lipids, are nontoxic, physiologically acceptable and metabolizable carriers that are relatively simple to make and administer.

A pharmaceutical composition (preparation) containing a compound of the invention can be administered to a subject by any of a number of routes of administration including, for example, orally; intramuscularly; intravenously; anally; vaginally; parenterally; nasally; intraperitoneally; subcutaneously; and topically. The composition can be administered by injection or by incubation.

In certain embodiments, the compound of the present invention may be used alone or conjointly administered with another type of anti-tumor therapeutic agent. As used herein, the phrase "conjoint administration" refers to any form of administration in combination of two or more different therapeutic compounds such that the second compound is administered while the previously administered therapeutic compound is still effective in the body {e.g., the two compounds are simultaneously effective in the patient, which may include synergistic effects of the two compounds). For example, the different therapeutic compounds can be administered either in the same formulation or in a separate formulation, either concomitantly or sequentially. Thus, an individual who receives such treatment can benefit from a combined effect of different therapeutic compounds. It is contemplated that the compound of the present invention will be administered to a subject (e.g., a mammal, preferably a human) in a therapeutically effective amount (dose). By "therapeutically effective amount" is meant the concentration of a compound that is sufficient to elicit the desired therapeutic effect (e.g., treatment of a condition, the death of a neoplastic cell). It is generally understood that the effective amount of the compound will vary according to the weight, sex, age, and medical history of the subject. Other factors which influence the effective amount may include, but are not limited to, the severity of the patient's condition, the disorder being treated, the stability of the compound, and, if desired, another type of therapeutic agent being administered with the compound of the invention. Typically, for a human subject, an effective amount will range from about 0.001 mg/kg of body weight to about 50 mg/kg of body weight. A larger total dose can be delivered by multiple administrations of the agent. Methods to determine efficacy and dosage are known to those skilled in the art. See, for example, Isselbacher et al. (1996) Harrison's Principles of Internal Medicine 13 ed., 1814-1882, herein incorporated by reference.

EXEMPLIFICATION

The invention now being generally described, it will be more readily understood by reference to the following examples, which are included merely for purposes of illustration of certain aspects and embodiments of the present invention, and are not intended to limit the invention.

EXAMPLE 1 Inhibition of Cell Growth by Compound 2

The ability of Compound 2, dissolved in DMSO, to inhibit the growth of BJELR cells was measured. The compound was assayed by the Sytox primary screen, a phenotypic assay which monitors alterations in cell survival-proliferation as a result of compound treatment. It was devised as high throughput method to identify compounds which specifically alter the growth potential of cells harboring the causative mutations found in cancer patients while not affecting the growth of normal cells. The assay relies upon an inexpensive, simple and reliable readout of a membrane impermeable fluorescent dye (Sytox, from Molecular Probes) which binds to nucleic acid. In healthy cells, no signal is detected because the cell's membrane is intact and the dye will not enter. However, if a cell's membrane is compromised as a result of apoptosis or necrosis, a fluorescent signal proportional to the number of similarly affected cells will be detected. By utilizing a two-step readout (final read in the presence of detergent to permit labeling of all cells), the assay can identify compounds which produce cytostasis, cytotoxicity and/or mitogenesis. The first read or "dead cell" read, provides an estimate of the toxicity of a given compound by indicating the number of dead or dying cells in the culture at the time of assay. The second read or "total cell" read, captures both the cumulative effects of cytoxicity in reducing the size of the cell population as well as any cytostatic or antiproliferative effects a test compound may exert on the cells in the test population in the absence of toxicity.

For the purpose of screening, the previously described BJ-TERT line was defined as the "normal" reference cell line and and BJ-TERT/LT/ST/RAS^V12 cells were the tumorigenic cell line. Cells were seeded overnight in 96 well plates at densities that without treatment would permit 95% confluence in the wells 72 hours later. The following day, the ceils were exposed to test compounds in a dilution series for a period of 48 hours. Following this incubation period, the Sytox reagent was added to the cultures at the manufacturer's recommended concentration and the dead cell fluorescence read was taken. After completion of this measurement, the detergent Saponin was added to each well of the cultures to permeabilize the membranes allowing the Sytox reagent to enter every cell, thereby facilitating measurement of the total number of cells remaining in the culture. For data evaluation, no differentiation was made between compounds which exhibited cytotoxic or cytostatic effects.

Compounds 2 inhibited the growth of BJELR cells with an JCso of about 1.5 μM.

EXAMPLE 2 Identification of Compounds with Increased Potency or Activity in the Presence of Specific Cancer- Related Alleles

Described here is a method to identify compounds with increased potency or activity in the presence of hTERT, LT, ST, E6, E7 or RAS^V'². Although the method described herein uses hTERT, LT, ST, E6, E7 and RAS^{V 12} as transforming genes, other studies can make use of a wide variety of cancer-associated alleles using this methodology in order to define the signaling networks that involve many oncogenes and tumor suppressors. The primary screen tests the effect of treating tumorigenic BJ-TERT/LT/ST/RAS¹^¹² engineered tumorigenic cells with each compound for 48 hours at a concentration of 4 μg/mL, corresponding to 10 μM for a compound with a molecular weight of 400. Cell viability is measured using the dye calcein acetoxymethyl ester (calcein AM) (Wang et al., 1993, Hum. Immunol. 37, 264-270), which is a non-fluorescent compound that freely diffuses into cells. In live cells, calcein AM is cleaved by intracellular esterases, forming the anionic fluorescent derivative calcein, which cannot diffuse out of live cells. Hence, live cells exhibit a green fluorescence when incubated with calcein AM, whereas dead cells do not. Compounds that display 50% or greater inhibition of staining with the viability dye calcein AM in B J-TERT/LT/ST/RAS^VI2 cells are subsequently tested in a two-fold dilution series in BJ and BJ-TERT/LT/ST/RAS^V12 cells to identify compounds that display synthetic lethality, which is lethality in tumorigenic cells but not in isogenic primary cells.

A selectivity metric that measures the shift in the IC₅0 (concentration required for 50% inhibition of viability signal) of a compound in two different cell lines is as follows. To calculate this selectivity score between two cell lines, the IC₅₀ for a compound in one cell line is divided by the IC₅₀ for the same compound in a second cell line. Thus, a compound that must be used at a four-fold higher concentration in one cell line relative to a second cell line would have a selectivity score of 4. The "tumor selectivity score" is calculated for each compound, by dividing the IC₅₀ value for the compound in the parental, primary BJ cells by the IC₅₀ value for the compound in engineered BJ-TERT/LT/ST/RAS^VI2 cells, containing all four genetic elements required to create tumorigenic cells.

These engineered tumorigenic cells make use of dominantly acting viral oncoproteins such as LT, ST, E6 and E7. These viral proteins are possibly involved in cell transformation in specific forms of cancer, namely simian virus 40-induced malignant mesothelioma (Testa and Giordano, 2001, Semin Cancer Biol JJ, 31-8) and human papillomavirus-induced cervical carcinoma (Bosch et al., 2002, J Clin Pathol 55, 244-65), and have been used to disrupt ρ53 and pRB function to transform cells in vitro and in vivo (Elenbaas et al., 2001 , Genes Dev 15, 50-65; Jorcyk et al., 1998, Prostate 34, 10-22; Perez-Stable et al., 1997, Cancer Res 57, 900-6; Rich et al., 2001 , Cancer Res 61, 3556-60; Sandmoller et al., 1995,

Cell Growth Differ 6, 97-103). These two different methods are used for inactivating cellular proteins, (they test the effects of both LT and E6/E7-based inactivation of pRB and p53) in order to control for idiosyncratic effects that might be observed with a specific viral protein. The selectivity of these compounds is also confirmed in a cell line expressing dominant negative inhibitors of p53 and pRB that are not derived from viral elements. This cell line expresses (i) a truncated form of p53 (p53DD) that disrupts tetramerization of endogenous p53, (ii) a CDK4^R24C mutant resistant to inhibition by pl6^INK4A and pl5^1NK4B (the major negative regulators of CDK4) and (iii) cyclin Dl. The effects of compounds of the invention are tested at a range of concentrations in these cells, which are referred to as BJ-TERT/ p53DD/ CDK4^R24C/D1/ ST/ RAS^V12 cells.

EXAMPLE 3 Characterization of cell death The purpose of this example is to characterize the type of cell death induced by compounds of the invention in tumorigenic BJ-TERT/LT/ST/RAS^VI2 cells. Apoptotic cell death is characterized by alterations in nuclear morphology including pyknosis, karyorhexis and/or margination of chromatin (Majno and Joris, 1995, Am J Pathol 146, 3-15). To determine whether a compound induces apoptosis, the nuclear morphology tumorigenic cells treated with CPT or a compound of the invention is monitored using fluorescence microscopy. Nuclear morphological change is required of apoptotic cells.

To confirm that a compound induces cell death, rather than cell detachment, cell viability is quantitated in the presence of the compound using Alamar Blue (Ahmed et al., 1994, J. Immunol. Methods 170, 21 1-224), a viability dye that measures intracellular reductive potential.

The following methods and materials can be used to characterize the activities of the compounds of the invention.

Constructs and retroviruses

Expression constructs for hTERT, LT, ST, SV40 Early Region, and HRAS^VI2 are used as previously described (Hahn et al., 1999, supra; Hahn et al., 2002, supra)). hTERT- pWZL-Blastε, E6-pWZL-zeoε, and E6E7-ρWZL-Zeoε were previously described (Lessnick et al., 2002, supra). The E6 and LT cDNAs were cloned into the pWZL-Hygroε retroviral vector (a kind gift from J. Morgensteni, Millenium Pharmaceuticals). Vesicular stomatitis virus-G glycoprotein pseudotyped retroviruses are prepared, and infections carried out. as described previously (Lessnick et al., 2002, supra). Cell lines

TIP5 primary fibroblasts (Lessnick et al., 2002, supra) are prepared from discarded neonatal foreskins and are immortalized by infection with hTERT-pWZL-blastε or hTERT- pBabe-hygro retroviruses and selection with either blasticidin or hygromycin, respectively. BJ cells were a gift of Jim Smith. hTERT- immortalized fibroblasts are infected with the indicated retroviruses and selected for the appropriate markers. All BJ derivatives are cultured in a 1:1 mixture of DMEM and Ml 99 supplemented with 15% inactivated fetal bovine serum, penicillin and streptomycin (pen/strep). TIP5 cells are grown in DMEM containing 10% FBS and pen/strep. All cell cultures are incubated at 37°C in a humidified incubator containing 5% CO2.

Compound formulation

All compound formulations are prepared as 4 mg/ml solutions in DMSO in 384-well polypropylene plates (columns 3-22) and stored at -20 ⁰C.

Calcein AM viability assay Calcein acetoxylm ethyl ester (AM) is a cell membrane-permeable, non-fluorescent compound that is cleaved by intracellular esterases to form the anionic, cell-impermeable, fluorescent compound calcein. Viable cells are stained by calcein because of the presence of intracellular esterases and because the intact plasma membrane prevents fluorescent calcein from leaking out of cells (Wang et al., 1993, supra). Cells are seeded in 384-well plates using a Zymark Sciclone ALH, treated with each compound in triplicate at 4 μg/mL in the primary screen for two days, washed with phosphate-buffered saline on a Packard Minitrak with a 384-well washer and incubated for four hours with 0.7 μg/mL calcein (Molecular Probes). Total fluorescence intensity in each well is recorded on a Packard Fusion platereader, and converted to a percent inhibition of signal by subtracting the instrument background and dividing by the average signal obtained when cells were not treated with any compound.

Alamar Blue Viability Assay

Alamar Blue is reduced by mitochondrial enzyme activity in viable cells, causing both cσlorimetric and fluorescent changes (Nociari et al., 1998, J. Immunol. Methods 13, 157- 167). Cells are seeded at a density of 6000 cells (50 μl) per well in a 384-well black, clear bottom plate using a syringe bulk dispensor (Zymark). 10 μl is removed from a two-fold serially diluted plate (6X final concentration) using a 384 fixed cannula head, making the final concentration 20 μg/ml in the well with highest concentration. The plates are incubated for 24 hours. Alamar Blue (Biosource International) is added to each well by diluting 1:10 and incubated for 16 hours at 37 ⁰C. Fluorescence intensity is determined using a Packard Fusion platereader with an excitation filter centered on 535 nm and an emission filter centered on 590 nm. Average percentage inhibition at each concentration is calculated. The Alamar Blue assay does not involve washing the cells.

Screening

Replica daughter plates are prepared with a Zymark Sciclone ALH and integrated Twister II by diluting stock plates 50 fold in medium lacking serum and pen/strep to obtain a compound concentration in daughter plates of 80 μg/ml with 2% DMSO. Assay plates are prepared by seeding cells in black, clear bottom 384-well plates in columns 1-23 (6000 cells/well in 57 μl) using a syringe bulk dispenser. Columns 3-22 are treated with compounds from a daughter library plate by transferring 3 μl from the daughter library plate using 384- position fixed cannula array. The final compound concentrations in assay plates are thus 4 μg/ml. The assay plates are incubated for 48 hours at 37 ⁰C in humidified incubator containing 5% CO₂. Plate processing for the calcein AM viability assay is performed using an integrated Minitrak/Sidetrak robotic system from Packard Bioscience (Perkin Elmer). Assay plates are washed with phosphate buffered saline, and 20 μl of calcein AM (0.7 μg/ml) per well is added. Plates are incubated at room temperature for 4 hours. Fluorescence intensity is determined using a Fusion platereader with filters centered on an excitation of 485 nm and an emission of 535 nm.

Retesting of compounds in a dilution series

Stocks are prepared in DMSO at a concentration of 1 mg/ml in 384-well polypropylene plates with a 16-point, two-fold dilution dose curve of each compound in a column, in duplicates. Column 1 -2 and 23-24 were left empty for controls. Daughter retest plates are prepared from stock retest plate by diluting 66.6 fold in DMEM in 384-well deep- deep well plates (4.5 μl transfer into 300 μl). Cells are seeded at a density of 6000 per well in 40 μl, and 20 μl is added from a daughter retest plate. The plates are incubated for two days at 37 ⁰C with 5% CO₂. Data Analysis

Mean RFU (relative fluorescence units) for untreated cells is calculated by averaging columns 1, 2, and 23 (wells with cells but lacking compounds). The calcein background is calculated by averaging column 24 (wells with calcein. but lacking cells). Percentage inhibition of each well is calculated as [1 - (RFU - calcein control)/(untreated cell — calcein control)* 100]. Compounds causing at least 50% inhibition of calcein staining in the primary screen are tested for selectivity towards BJ-TERT/LT/ST/RAS^VI2 engineered tumor cells by testing in BJ primary and BJ-TERT/LT/ST/RAS^VI2 cells at a range of concentrations. Selective compounds are retested in all engineered cell lines. Nuclear Morphology Assay

200,000 tumorigenic BJ-TERT/LT/ST/RAS^V12 cells are seeded in 2 mL on glass coverslips in each well of a six-well dish, treated with nothing (NT) or a compound of the invention in growth medium for 18 hours while incubating at 37 °C with 5% CO₂- Nuclei are stained with 25 μg/mL Hoechst 33342 (Molecular Probes) and viewed using an oil immersion IOOX objective on a fluorescence microscope.

Cell size measurements

200,000 BJ-TERT/LT/ST/RAS^{V 12} cells are seeded in six-well dishes in 2 mL growth medium only (No treatment) or a compound of the invention. After 24 hours, cells are released with trypsin/EDTA, diluted to 10 mL in growth medium, and. the cell size distribution of each sample is determined on a Coulter Counter.

Cell counting assay for camptothecin activity

BJ-TERT/LT/ST/RAS^VI2 cells are seeded in 6-well dishes (200 000 cells/well; 2ml per well) and transfected in serum- and antibiotic-free medium using Oligofectamine (Life Technologies), with 100 nM siRNA per well in a total volume of one milliliter. 500 μl of medium containing 30% FBS is added 4 hours after transfection. Cells are treated with a compound of the invention 30 hours after transfection. Cells are removed with trypsin-EDTA and counted using a hemacytometer 75 hours after transfection. Western Blot Analysis

Caspase-3

BJ-TERT/LT/ST/RAS^V12 cells are seeded prior to the experiment at 5X10⁵ cells in 60 mm dishes. The cells are treated with 5 μg/ml of a compound of the invention for 2, 4, 6, 8 or 10 hours. One dish is maintained for camptothecin treatment (0.4 μg/ml for 24 h) as a positive control. Cells are lysed after each time point in lysis buffer (50 mM HEPES KOH pH 7.4, 40 nM NaCl, 2 mM EDTA, 0.5% Triton X-100, 1.5 mM Na₃VO₄, 50 mM NaF, 10 mM sodium pyrophosphate, 10 mM sodium beta-glycerophosphate and protease inhibitor tablet (Roche)). Protein content is quantified using a Biorad protein assay reagent. Equal amounts of protein are resolved on 16% SDS-polyacrylamide gel. The electrophoresed proteins are transblotted onto a PVDF membrane, blocked with 5% milk and incubated with anti-active caspase-3 polyclonal antibody (BD Pharmingen) at 1:1500 dilution overnight at 4 ⁰C. The membrane is then incubated in anti-rabbit-HRP (Santa Cruz Biotechnology) at 1:3000 dilution for 1 hour and developed with an enhanced chemiluminescence mixture (NEN life science, Renaissance). To test for equivalent loading in each lane, blots are stripped, blocked, and probed with an anti-elF-4E antibody (BD Transduction laboratories) at 1 :1000 dilution.

Topoisomerase-II a

BJ, BJ-TERT, BJ-TERT/LT/ST, BJ-TERT/LT/ST/RAS^{V 12}, BJ-TERT/LT/RAS^Vl2 and BJ-TERT/LT/RAS^V12/ST cells are seeded at IXlO⁶ cells per dish in 60 mm dishes. After overnight incubation of the cells at 37 ⁰C with 5% CO₂, the cells are lysed as described above and proteins resolved on a 10% polyacryl amide gel. The membrane is incubated with monoclonal anti-human topoisomerase Ilα pi 70 antibody (TopoGEN) at 1 :1000 dilution overnight at 4 ⁰C and then with anti-mouse HRP (Santa Cruz Biotechnology). Topoisomerase I (TOPl)

A 21-nucleotide double stranded siRNA directed against TOPl (nucleotides 2233- 2255, numbering from the start codon, Genbank accession J03250) is synthesized (Dharmacon, purified and desalted/deprotected) and transfected (100 nM) into and BJ- TERT/LT/ST/RAS^VI2 cells in six-well dishes with oligofectamine (Life Technologies). After 75 hours, cells are lysed and the expression level of TOPl determined by Western blot (Topogen, Cat# 2012-2, 1 : 1000 dilution). The protein loading level is determined by stripping and reprobing the same blot with an antibody directed against eIF-4E (BD Biosciences, Cat# 610270, 1 :500 dilution). Alternatively, IxIO⁶ cells are seeded in 60 mm dishes and grown overnight at 37 ⁰C with 5% CO₂, then lysed with 150 μl of lysis buffer. Cells are removed with a scraper and transferred to microcentrifuge tubes and incubated on ice for 30 minutes. The protein contents in the lysates are quantified using a Biorad protein estimation assay reagent. Equal amounts of protein are loaded on 10% gradient SDS- polyacrylamide gel. The electrophoresed proteins are transblotted onto PVDF membrane- After blocking with 5% dry milk, the membrane is incubated with mouse anti-human topoisomerase I antibody (Pharmingen) overnight at 4⁰C, then with anti-mouse peroxidase conjugate antibody (Santa Cruz Biotechnology).

Annexin V-FITC Apoptosis Assay

BJ-TERT/LT/ST/RAS^V12 cells are seeded at IXlO⁶ cells per dish in 100 mm dishes and allowed to grow overnight. Cells are treated with a compound of the invention for 6, 8 or 11 h. A camptothecin-treated (0.4 μg/ml) control is maintained, treated at the time of seeding for 20 hours. After the treatment, cells are harvested with trypsin/EDTA and washed once with fresh medium containing serum and then twice with phosphate buffered saline. Cells are resuspended in IX binding buffer (BD Pharmingen) at a concentration of 1X10⁶ cells/ml. 100 μl (IXlO⁵ cells) are incubated with 5 μl of Annexin V- FlTC (BD Pharmingen) and propidium iodiode (BD Pharmingen) for 15 minutes in the dark at room temperature. Then 400 μl of the IX binding buffer is added and the cells analyzed by flow cytometry (Becton- Dickinson). Data are acquired and analyzed using Cellquest software. Only viable cells that do not stain with propidium iodiode are analzyed for Annexin V-FITC staining using the FLl channel.

ROS analysis: flow cytometry analysis using H2DCF-DA 2',7'-dichlorodihydrofluorescein diacetate (H2DCF-DA) is a non-fluorescent cell permeable compound. The endogenous esterase enzyme inside the cell cleaves the diacetate part, and it can no longer pass out of the cell. Thus it accumulates in the cell. Then H2DCF reacts with ROS to form fluorescent dichlorofluorescene (DCF), which can be measured by flow cytometry in FLl channel. 1. Seed cells at 3X10⁵ cells per dish in 60mm dishes and allow to grow overnight.

2. Treat with the test compound for different period of time (1-10 hr). 3. Maintain one dish for untreated cells, compound treated cell and positive control dish (hydrogen peroxide treated) for each time point.

4. Incubate the cells with 10 μM of H2DCF-DA for 10 minutes at 37 ⁰C.

5. For positive control cells, after 5 minutes of H2DCF-DA loading, add 500 μM of hydrogen peroxide and incubate for 5 minutes further.

6. Harvest the cell by trypsinization.

7. Wash with cold PBS-twice.

8. Resuspend the pellet in 100 μl of PBS and transfer into 5 ml FACS tube.

9. Add 5 μl of propidium iodide (50 μg/ml) and incubate for 10 minutes on ice in dark.

10. Add 400 μl of PBS and analyze by flow cytometry (Becton-Dickinson).

1 1. Acquire the data and analyze using Cell Quest software program.

12. Take only propidium iodiode negative cells (viable cells) for the analysis for DCF staining using the FLl channel, PI in FL3 channel, plot a quadrant chart.

EXAMPLE 4 Identification and Characterization of Binding Partners of

Compounds Pull-down assays using immobilized compounds of the invention and cell lysates are used to identify binding partners for compounds of the invention inside a cell. Pull-down experiments arc performed with HT-1080, PANC-I , HEK293, BJEH and BJELR whole cell lysates. In these experiments, a compound of the invention is immobilized to Affigel 10 and incubated with lysate under standard pull-down conditions. The beads are washed and either eluted with 100 μM erastin or a compound of the invention or 0.8% N-lauroylsarcosine

(sarkosyl). The eluates are subjected to mass spectromctric analysis. The results of pull-down assays for Compounds 1-3 are shown in FIGS. 2 and 3.

Comparative Compound 1, which is disclosed in U.S. Application No. 10/340,430 and has the following structure:

was included in the pull-down assay for comparative purposes.

In pull-down assays using immobilized Compound 1 in conjunction with the lysates of BJLER, HT-1080 and PANC-I cells, VDACl and VDAC2 were identified in all three cell lines.

EXAMPLE 5 Expression Levels of Various VDAC lsoforms

Quantitative PCR (Q-PCR) experiments are performed to determine the relative quantities of mRNA (as a surrogate marker for gene expression) for a variety of genes in the "normal" BJEH cell line, and the tumorigenic BJELR line. For each of the VDAC isoforms (VDACl, 2 and 3), two regions of the mRNA are targeted for amplification. These regions are referred to as 1 and 1 -2, 2-1 and 2-2, and 3-1 and 3-2, respectively. The Q-PCR signal for mRNA fragment amplification for each gene of interest is compared to a series of internal standards, and scaled relative to the signal derived from GAPDH mRNA in the target cells.

EXAMPLE 6 Functional Evaluation of Compounds of the Invention on Various VDAC Isoforms

Functional assays help to validate the identified proteins as functional targets for compounds of the invention. In certain embodiments, isolated mitochondria might be used to see if a compound of the invention has any functional or phenotypic effects on mitochondria function. For example, phenotypic effects can be observed by microscope, while the detection of changes in the mitochondrial membrane potential, or the release of oxidative species upon treatment with a compound of the invention can be observed by using certain dyes, known in the art for detecting reactive oxygen species (ROS).

In certain other embodiments, validation experiments include photo-affinity labeling of the target protein with azido derivatives of the compounds of the invention, or compounds of the invention coupled to a bidentate affinity-tagged crosslinker (such as SBED), or a cleavable cross-linker.

In yet other embodiments, recombinant and over-expressed proteins are used in certain in vitro assays to assess any possible effects compounds of the invention have on their functions. Such in vitro assays could include, but are not limited to, direct binding (in vitro or BIACORE™), or efflux assays that could determine the channel properties of the VDAC isoforms.

In yet other embodiments, knockout mutants (cells or organisms) of those target proteins can be used. Compared to wild-types, these mutants could become either resistant or hypersensitive to compounds of the invention. Those knockout cell lines could also be used in high throughput screenings (HTS) to determine and/or evaluate the specificity of compounds of the invention.

In yet other embodiments, RNAi experiments for VDACs, Prohibitin and Ribophorin can also be used to assess any phenotypes upon treatment with compounds of the invention (e.g., resistance or hypersensitivity). According to this embodiment of the invention, SMARTPOOL^® siRNAs targeting VDACl , VDAC2 and VDAC3, respectively, can be purchased from Dharmacon (Lafayette, CO). Transfection conditions are then optimized, for example, using FUGENE™ and oligofectamine in 384-well plates, and a fluorescently labeled siRNA duplex. Such procedure resulted in ~90% transfection efficiency. ELR tumor cells can then be transfected with siRNAs against VDACl, VDAC2, VDAC3 or other targets identified by the methods described herein, and the dose-response to a compound of the invention can be measured.

INCORPORATION BY REFERENCE

All publications and patents mentioned herein are hereby incorporated by reference in their entirety as if each individual publication or patent was specifically and individually indicated to be incorporated by reference. In case of conflict, the present application, including any definitions herein, will control. EQUIVALENTS

While specific embodiments of the subject invention have been discussed, the above specification is illustrative and not restrictive. Many variations of the invention will become apparent to those skilled in the art upon review of this specification and the claims below. The full scope of the invention should be determined by reference to the claims, along with their full scope of equivalents, and the specification, along with such variations.

Claims

CLAIMS;

We claim:

1. A compound represented by Structural Formula (I):

or a pharmaceutically acceptable salt thereof, wherein:

Ring A and B is optionally substituted;

Ar is an optionally substituted phenyl group;

R₄ and R₅ are independently selected from the group consisting of — H, substituted or unsubstituted alkyl, substituted or unsubstituted alkenyl, substituted or unsubstituted alkynyl, substituted or unsubstituted non-aromatic heterocyclic and substituted or unsubstituted aryl, wherein alkyl, alkenyl and alkynyl are optionally interrupted by NR, O or S(O)_n; or R₄ and R₅ taken together form a 3- to 8-membered carbocyclic or heterocyclic group;

V is

Q is a substituted or unsubstituted alkyl; each R is independently -H, substituted or unsubstituted alkyl, substituted or unsubstituted alkenyl, substituted or unsubstituted alkynyl, substituted or unsubstituted ary! or substituted or unsubstituted non-aromatic heterocyclic; and each n is independently 0, I or 2, wherein the compound is not

A compound represented by Structural Formula (II):

or a pharmaceutically acceptable salt thereof, wherein:

Rings A and B are optionally further substituted;

R_a is a halogen, substituted or unsubstituted alkyl, substituted or unsubstituted alkenyl, substituted or unsubstituted alkynyl, substitued or unsubstitued aryl-O-, substituted or unsubstituted alkyl-O-, substituted or unsubstituted alkenyl-O- or substituted or unsubstituted alkynyl-O- , wherein alkyl, alkenyl and alkynyl are optionally interrupted by NR, O or S(O)_n;

R_b is H, halogen, Ci.galkoxy or C|_-8alkyl;

R₄ and R₅ are independently selected from the group consisting of — H, substituted or unsubstituted alkyl, substituted or unsubstituted alkenyl, substituted or unsubstituted alkynyl, substituted or unsubstituted non-aromatic heterocyclic and substituted or unsubstituted aryl, where alkyl, alkenyl and alkynyl are optionally interrupted by NR, O or S(O)₁₁; or R₄ and R₅ taken together form a 3- to 8-membered carbocyclic or heterocyclic group; V is

Q is a substituted or unsubstituted alkyl group; each R is independently -H₅ substituted or unsubstituted alkyl, substituted or unsubstituted alkenyl, substituted or unsubstituted alkynyl, substituted or unsubstituted aryl or substituted or unsubstituted non-aromatic heterocyclic; and each n is independently 0, 1 or 2, wherein the compound is not

3. The compound of claim 2, wherein Q is a substituted alkyl.

4. The compound of claim 3, wherein Q is substituted with a group capable of forming hydrogen bonds.

5. The compound of claim 4, wherein Q is substituted with -NHR.

6. The compound of claim 2, wherein Q is a Cs-Ci₂ alkyl.

7. The compound of claim 2, wherein R4 and R₅ are -H or a substituted or unsubstituted alkyl group.

8. The compound of claim 7, wherein R₄ and R5 are — H or an unsubstituted C1-C4 alkyl group.

9. The compound of claim 2, wherein R_a is a halogen or a substituted or unsubstituted alkyl-O- group.

10. The compound of claim 9, wherein R_a is an unsubstituted C₁-C₄ alkyl-O- group.

11. The compound of claim 10, wherein R_b is — H.

12. The compound of claim 9, wherein R_n and R_b are each a halogen.

13. The compound of claim 2, wherein Rings A and B are not further substituted or are substituted with one or more of nitro, halogen, substituted or unsubstituted alkyl, substituted or unsubstituted aryl, substituted or unsubstituted non-aromatic heterocyclic, -CN₃ -COOR', -CON(R)₂, -SO₂N(R)₂, -OH and -OR'.

14. A compound represented by Structural Formula (III):

or a pharmaceutically acceptable salt thereof, where:

Rings A and B are optionally further substituted;

R4 and R5 are independently selected from the group consisting of -H, substituted or unsubstituted alkyl, substituted or unsubstituted alkenyl, substituted or unsubstituted alkynyl, substituted or unsubstituted non-aromatic heterocyclic and substituted or unsubstituted aryl, where alkyl, alkenyl and alkynyl are optionally interrupted by NR, O or S(O)_n; or R₄ and R₅ taken together form a 3- to 8-membered carbocyclic or heterocyclic group;

V is

Q is a substituted or unsubstituted alkyl group; each R is independently -H, substituted or unsubstituted alkyl. substituted or unsubstituted alkenyl, substituted or unsubstituted alkynyl, substituted or unsubstituted aryl or substituted or unsubstituted non-aromatic heterocyclic; and each n is independently 0, 1 or 2, wherein the compound is not

15. The compound of claim 14, wherein Q is a substituted alkyl.

16. The compound of claim 15, wherein Q is substituted with a group capable of forming hydrogen bonds.

17. The compound of claim 16, wherein Q is substituted with -NHR.

18. The compound of claim 14, wherein Q is a C₅-C [₂ alkyl.

19. The compound of claim 14, wherein R₄ and R₅ are -H or a substituted or unsubstituted alkyl group.

20. The compound of claim 19, wherein R₄ and R₅ are -H or an unsubstituted C1-C4 alkyl group.

21. The compound of claim 14, wherein R) is a substituted or unsubstituted alkyl group.

22. The compound of claim 21 , wherein Ri is an unsubstituted Ci-C₄ alkyl group.

23. The compound of claim 14, wherein Rings A and B are not further substituted or are substituted with one or more of halogen, substituted or unsubstituted alkyl, substituted or unsubstituted aryl, substituted or unsubstituted non-aromatic heterocyclic, -CN, -COOR', -CON(R)₂, -SO₂N(R)₂, -OH and -OR'.

24. A compound represented by Structural Formula (I):

or a pharmaceutically acceptable salt thereof or a metabolic precursor thereof, where:

Ar is an optionally substituted phenyl group;

R₄ and R₅ are independently selected from the group consisting of -H, substituted or unsubstituted alkyl, substituted or unsubstituted alkenyl, substituted or unsubstituted alkynyl, substituted or unsubstituted non-aromatic heterocyclic and substituted or unsubstituted aryl, where alkyl, alkenyl and alkynyl are optionally interrupted by NR, O or S(O)_n; or R₄ and R₅ taken together form a 3- to 8-membered carbocyclic or heterocyclic group;

V is

:

Ring C is a substituted or unsubstituted heterocyclic aromatic or non-aromatic ring;

A is NR or O; or A is a covalent bond;

L is a substituted or unsubstituted hydrocarbyl group optionally interrupted by one or more heteroatoms selected from ^"N, O and S;

Q is selected from the group consisting of -R', -C(O)R', -C(O)N(R)₂, -C(O)OR' and -S(O)₂R'; each R is independently -H, substituted or unsubstituted alkyl, substituted or unsubstituted alkenyl, substituted or unsubstituted alkynyl, substituted or unsubstituted aryl or substituted or unsubstituted non-aromatic heterocyclic; each R' is independently a substituted or unsubstituted alkyl, substituted or unsubstituted alkenyl, substituted or unsubstituted alkynyl group, substituted or unsubstituted non-aromatic heterocyclic or substituted or unsubstituted aryl group; and each n is independently 0, 1 or 2.

25. A pharmaceutical composition comprising a compound of any of claims 1-24 and a pharmaceutically acceptable carrier.

26. A method of treating a condition in a mammal, comprising administering to the mammal a therapeutically effective amount of a compound of any of claims 1-24.

27. The method of claim 26, wherein the condition is further characterized by substantially wild-type level of Rb activity.

28. The method of claim 26 or 27, wherein the condition is characterized by cells with enhanced Ras signaling activity; and altered activity of a cellular target protein of the S V40 small t antigen.

29. The method of claim 26 or 27, wherein the compound kills cells in the mammal by a non-apoptotic mechanism.

30. The method of claim 29, wherein said cells have enhanced Ras signaling activity.

31. The method of claim 30, wherein said cells have measurable Ras signaling activity.

32. The method of claim 29, wherein said cells express SV40 small t antigen.

33. The method of claim 32, wherein said cells overexpress SV40 small t antigen.

34. The method of claim 29, wherein said cells express VDAC

35. The method of claim 34, wherein said cells overexpress VDAC.

36. The method of claim 29, wherein said cells have substantially reduced activity of phosphatase PP2A

37. The method of claim 26, wherein said condition is cancer.

38. The method of claim 37, wherein said cells are induced to express SV40 small t antigen.

39. The method of claim 37, wherein said cells are induced to express SV40 small t antigen by infecting said cells with a viral vector overexpressing SV40 small t antigen.

40. The method of claim 39, wherein said viral vector is a retroviral vector or an adenoviral vector.

41. The method of claim 26, further comprising conjointly administering to said mammal an agent that kills cells through an apoptotic mechanism.

42. The method of claim 41, wherein said agent is a chemotherapeutic agent.

43. The method of claim 42, wherein said chemotherapeutic agent is selected from: an EGF-receptor antagonist, arsenic sulfide, adriamycin, cisplatin, carboplatin, cimetidine, carminomycin, mechlorethamine hydrochloride, pentamethylmelamine, thiotepa, teniposide, cyclophosphamide, chlorambucil, demethoxyhypocrellin A, melphalan, ifosfamide, trofosfamide, Treosulfan, podophyllotoxin or podophyllotoxin derivatives, etoposide phosphate, teniposide, etoposide, leurosidine, leurosine, vindesine, 9-aminocamptothecin, camptoirinotecan, crisnatol, megestrol, methopterin, mitomycin C, ecteinascidin 743, busulfan, carmustine, lomustine, lovastatin, 1- methyl-4-phenylpyridinium ion, semustine, staurosporine, streptozocin, phthalocyanine, dacarbazine, aminopterin, methotrexate, trimetrexate, thioguanine, mercaptopurine, fludarabine, pentastatin, cladribin, cytarabine, porfϊromycin, 5- fluorouracil, 6-mercaptopurine, doxorubicin hydrochloride, leucovorin, mycophenolic acid, daunorubicin, deferoxamine, floxuridine, doxifluridine, raltitrexed, idarubicin, epirubican, pirarubican, zorubicin, mitoxantrone, bleomycin sulfate, actinomycin D, safracins, saframycins, quinocarcins, discodeπτiolides, vincristine, vinblastine, vinorelbine tartrate, vertoporfin, paclitaxel, tamoxifen, raloxifene, tiazofuran, thioguanine, ribavirin, ElCAR, estramustine, estramustine phosphate sodium, flutamide, bicalutamide, buserelin, leuprolide, pteridines, enediynes, levamisole, aflacon, interferon, interleukiris, aldesleukin, filgrastim, sargramostim, rituximab, BCG, tretinoin, betamethasone, gemcitabine hydrochloride, verapamil, VP- 16, altretamine, thapsigargin, oxaliplatin, iproplatin, tetraplatin, lobaplatin, DCP, PLD- 147, JMl 18, JM216, JM335, satraplatin, docetaxel, deoxygenated paclitaxel, TL-139, 5'-nor-anhydrovinblastine, camptothecin, irinotecan, topotecan, BAY 38-3441, 9- nitrocamptothecin, exatecan, lurtotecan, gimatecan, homocamptothecins diflomotecan and 9-aminocamptothecin, SN-38, ST1481 , karanitecin, indolocarbazoles, protoberberines, intoplicines, idenoisoquinolones, benzo-phenazines and NB-506.

44. A method of killing a cell, comprising administering to the cell an effective amount of a compound of any of claims 1-24 and an agent that increases the abundance of VDAC in the cell.

45. The method of claim 44, wherein the VDAC is VDACl , VDAC2 or VDAC3.

46. The method of claim 44, wherein said cell is a cancer cell.

47. The method of claim 44, wherein said agent comprises a polynucleotide encoding VDAC.

48. The method of claim 44, wherein said agent is a VDAC protein adapted to be transported into the cell.

49. The method of claim 48, wherein said agent is a VDAC protein fused with a heterologous internalization domain.

50. The method of claim 48, wherein said agent is a liposome preparation comprising a VDAC protein.

51. The method of claim 44, wherein said agent enhances or inhibits endogenous VDAC expression.

52. The method of claim 51 , wherein said agent enhances VDAC expression.

53. The method of claim 44, wherein said agent inhibits the function of a VDAC inhibitor.

54. A method of killing a cell, comprising administering to the cell an effective amount of a compound of any of claims 1-24 and an agent that decreases the abundance of VDAC in the cell.

55. A method of promoting cell death or slowing cell growth, comprising administering to the cell an effective amount of a compound of any of claims 1-24.

56. A method of reducing the growth rate of a tumor, comprising contacting the tumor with an effective amount of a compound of any of claims 1-24.

57. A method of increasing the sensitivity of a tumor cell to a chemotherapeutic agent, comprising contacting the tumor cell with an effective amount of a compound of any of claims 1-24.

58. A packaged pharmaceutical comprising:

(i) a therapeutically effective amount of a compound of any of claims 1-24; and

(ii) instructions, a label or both for administration of the agent for the treatment of patients having cancer.