Carboline derivatives useful in the treatment of cancer

1. A method for treating a solid tumor cancer comprising administering a therapeutically effective amount of a compound of Formula (IV):

or a pharmaceutically acceptable salt, racemate or stereoisomer of said compound, to a subject in need thereof; wherein

X is hydrogen; C 1 to C 6 alkyl optionally substituted with one or more halogen substituents; hydroxyl halogen or C 1 to C 5 alkoxy optionally substituted with phenyl;

R o is hydrogen; halogen; cyano; nitro; sulfonyl substituted with C 1 to C 6 alkyl or morpholinyl; amino optionally substituted with C 1 to C 6 alkyl, —C(O)—R b , —C(O)O—R b , alkylsulfonyl, morpholinyl or tetrahydropyranyl; C 1 to C 6 alkyl optionally substituted with one or more substituents independently selected from hydroxyl, halogen or amino; —C(O)—R n ; or —OR a ;

R a is hydrogen; C 2 to C 8 alkenyl; —C(O)O—R b ; —C(O)—NH—R b ; C 1 to C 8 alkyl optionally substituted with one or more substituents independently selected from hydroxyl, halogen, C 1 to C 4 alkoxy, amino, alkylamino, dialkylamino, acetamide, —C(O)—R b , —C(O)O—R b , aryl, morpholinyl, thiomorpholinyl, pyrrolidinyl, piperidinyl, piperazinyl, 1,3-dioxolan-2-one, oxiranyl, tetrahydrofuranyl, tetrahydropyranyl, 1,2,3-triazole, 1,2,4-triazole, furan, imidazole, isoxazole, isothiazole, oxazole, pyrazole, thiazole, thiophene or tetrazole;

wherein amino is optionally substituted with C 1 to C 4 alkoxycarbonyl, imidazole, isothiazole, pyrazole, pyridine, pyrazine, pyrimidine, pyrrole, thiazole or sulfonyl substituted with C 1 to C 6 alkyl, wherein pyridine and thiazole are each optionally substituted with C 1 to C 4 alkyl;

wherein alkylamino and dialkylamino are each optionally substituted on alkyl with hydroxyl, C 1 to C 4 alkoxy, imidazole, pyrazole, pyrrole or tetrazole; and,

wherein morpholinyl, thiomorpholinyl, pyrrolidinyl, piperidinyl, piperazinyl and oxiranyl are each optionally substituted with —C(O)—R n , —C(O)O—R n or C 1 to C 4 alkyl, wherein C 1 to C 4 alkyl is optionally substituted with hydroxyl;

R b is hydroxyl; amino; alkylamino optionally substituted on alkyl with hydroxyl, amino, alkylamino or C 1 to C 4 alkoxy; a C 1 to C 4 alkoxy; C 2 to C 8 alkenyl; C 2 to C 8 alkynyl; aryl optionally substituted with one or more substituents independently selected from halogen and C 1 to C 4 alkoxy; furan; or C 1 to C 8 alkyl optionally substituted with one or more substituents independently selected from C 1 to C 4 alkoxy, aryl, amino, morpholinyl, piperidinyl or piperazinyl;

R d is phenyl substituted with one or more substituents independently selected from hydrogen, halogen, nitro, C 1 to C 6 alkyl, —C(O)O—R e , and —OR e ;

R e is hydrogen; C 1 to C 6 alkyl optionally substituted with one or more substituents independently selected from halogen and alkoxy; or phenyl optionally substituted with one or more substituents independently selected from halogen or alkoxy; and

R n is a hydroxyl, C 1 to C 4 alkoxy, amino or C 1 to C 6 alkyl,

wherein the compound inhibits VEGF production in a HT1080 solid tumor grown in a nude mouse, inhibits HT1080 solid tumor growth in a nude mouse or inhibits angiogenesis in a HT1080 solid tumor grown in a nude mouse.

2. The method of claim 1 , wherein said compound is selected from the group consisting of:

or a pharmaceutically acceptable salt, racemate or stereoisomer thereof.

3. The method of claim 1 , where said compound has a chiral carbon at the point of attachment of the R o substituted phenyl on the compound of Formula (IV) and said compound is an (S) isomer at said chiral carbon.

4. The method of claim 1 , wherein said compound is administered simultaneously or sequentially with one or more additional agents useful in the treatment of cancer.

5. The method of claim 4 , wherein said one or more additional agents useful in the treatment of cancer is selected from the group consisting of paclitaxel, fluorouracil, irinotecan, thalidomide, gemcitabine, squalamine, endostatin, angiostatin, neovastat, lenalidomide, vitaxin, 2-methoxyestradiol, carboxyamidotriazole, combretastatin A4 phosphate, 5-[1,2-Dihydro-2-oxo-3H-indol-3-ylidene)methyl]-2,4-dimethyl-1H-pyrrole-3-propanoic acid, sunitinib malate, rebimastat, metastat, cilengitide, ramucirumab, vatalanib, vandetanib, halofuginone, hydrobromide, celecoxib, interferon alpha, interleukin-12, and bevacizumab.

6. The method of claim 4 , wherein said one or more additional agents are selected from bevacizumab, paclitaxel and fluorouracil.

7. The method of claim 1 , wherein the solid tumor cancer is selected from a group consisting of a solid tumor carcinoma, a pediatric solid tumor, a Wilms tumor, a neuroblastoma, a carcinoma of the epidermis, a malignant melanoma, a cervical carcinoma, a cervical cancer, a colon carcinoma, a colon cancer, a lung carcinoma, a lung cancer, a renal carcinoma, and a solid tumor sarcoma.

8. The method of claim 1 or 2 , wherein the compound has an EC 50 of less than 50 nM for inhibiting hypoxia-induced VEGF expression in cultured HeLa cells.

9. The method of claim 1 or 2 , wherein the compound inhibits VEGF production in a HT1080 solid tumor grown in a nude mouse.

10. The method of claim 1 or 2 , wherein the compound inhibits HT1080 solid tumor growth in a nude mouse.

11. The method of claim 1 or 2 , wherein the compound inhibits angiogenesis in a HT1080 solid tumor grown in a nude mouse.

12. The method of claim 2 , wherein said compound has a carboline scaffold and at a chiral carbon of said scaffold, said compound is an (S) enantiomer.