Trichostatin A (TSA) was originally isolated as an antifungal antibiotic along with its fermentation congeners trichostatin B ((TSA)3-Fe) and the D-glucopyranosides trichostatin C and D. TSA inhibits HDAC in the low nanomolar range and is an inducer of histone hyperacetylation, both in vitro and in vivo. It inhibits all class I and II deacetylases to a similar extent in both tumor and non-tumor cells, although HDAC4 is slightly resistant when compared with HDAC1 and HDAC6. Class III HDAC is not affected by TSA. It has been shown that TSA dosedependently inhibits growth and induces apoptosis in a plethora of carcinoma cell lines in vitro. Recently, it was also found that TSA inhibits angiogenesis, which is important for the growth and metastasis of solid tumors, both in vivo and in vitro. In HT-29 colon carcinoma cells, a single dose of TSA induced transient hyperacetylation of histone H4 resulting in the induction of p21WAF1/Cip1 and inhibition of cellular proliferation at both the G1 and G2 phases of the cell cycle. Growth inhibition was associated with decreased cyclin D1 mRNA and cdk6 protein levels and increased cyclin D3 protein and p21WAF1/Cip1 mRNA levels. Cyclin D1 protein, cyclin D3 mRNA, cdk2 and cdk4 remained unaffected. In addition, TSA induced apoptosis by upregulating the expression of the pro-apoptotic genes ID1, ID2 and ID3, whereas the expression of the anti-apoptotic genes BclxL and Hsp27 was decreased In vivo, TSA induces differentiation and shows chemotherapeutic activity against N-methylnitrosureainduced rat mammary cancer without toxic side effects. TSA may also have therapeutic potential for the treatment of a variety of genetic and infectious diseases since silenced, transduced genes are reactivated probably due to structural changes of the chromatin on integrated viral sequences.

Oxi0-4503 (now known as combretastatin A1 phosphate), a diphosphate prodrug of combretastatin A1, was developed by Mateon therapeutics as a second-generation, dual-mechanism vascular disrupting agent from the combretastatin family. On November 21, 2012, Oxi-4503 has been granted orphan designation by the US Food and Drug Administration for the treatment of acute myelogenous leukemia. It is known that the orphan drug designation qualifies a company for several benefits, including the potential for market exclusivity, development grants, and tax credits. Oxi0-4503 is currently participating in phase I/II clinical trial the treatment of patients with acute myelogenous leukemia or myelodysplastic syndrome. In addition, phase I clinical trial was successfully completed where was studied the safety of Oxi0-4503 in patients with advanced solid tumors.

Tanomastat (previously known as BAY 12-9566) is an inhibitor of angiogenesis and a biphenyl matrix metalloprotease (MMP). The drug was selective towards MMPs 2,3, and 9 and no activity against MMP1. Tanomastat was developed for the treatment of cancer and arthritis. Tanomastat participated in phase III clinical trials as maintenance therapy in patients with advanced ovarian cancer, and in patients with pancreatic, lung cancers. However, all studied were discontinued after the recommendation of the independent data safety monitoring board.

Latrunculin B originates from Latrunculia (now Negombata) magnifica, a sponge from the Red Sea. Latrunculin B inhibits the assembly of actin microfilaments by 1:1 molecular binding of free actin monomers in the cell cytoplasm. It may be a potential therapeutic agent for glaucoma. Latrunculin B induced destabilization of the actin microfilament and apoptosis in a dose-dependent manner, as demonstrated by morphological changes and nuclear condensation in the PC3M cells. In addition, it resulted in an increase in the levels of gamma-H2AX recruitment, implicating the induction of DNA damage, including double-strand breaks. Induction of Bax, with little effect on Bcl-2 expression, indicated that actin disruption causes apoptosis through activation of Bax signaling in PC3M cells. This data might helps to develop the strategy for actin-based anticancer chemotherapy against highly metastatic prostate cancer.

Latrunculin A is a naturally occurring toxin that can be purified from the red sea sponge Latrunculia magnifica. It disrupts actin polymerization and prevents mitotic spindle formation; therefore preventing proper cellular replication. It was discovered that latrunculin A has strong anticancer effects, and it was investigated as a treatment candidate for peritoneal dissemination of gastric cancer.

9-(N-methyl-L-isoleucine)-cyclosporin A (NIM-811, SDZ 811) is a cyclosporin A analog that is completely devoid of immunosuppressive capacity but exhibits potent and selective anti-human immunodeficiency virus type 1 (HIV-1) activity. NIM-811 interferes at two stages of the viral replication cycle: (i) translocation of the preintegration complex to the nucleus and (ii) production of infectious virus particles. NIM-811 induces a concentration-dependent reduction of HCV RNA in the replicon cells with an IC50 of 0.66 uM at 48 h. NIM-811 blocks the mitochondrial permeability transition induced by calcium and inorganic phosphate. NIM-811 blocks cell killing and prevents in situ mitochondrial inner membrane permeabilization and depolarization during tumor necrosis factor-α–induced apoptosis to cultured rat hepatocytes.Novartis discontinued development of SDZ 811 as an oral therapy for hepatitis C and HIV-1 infections.

2-(1-Hexyloxyethyl)-2-devinyl pyropheophorbide-a (HPPH), a chlorin-based photosensitize, is used in photodynamic therapy. It has been shown the therapeutic potential of HPPH in phase II clinical trials for the treatment of esophageal cancer. Besides, HPPH participated in clinical trials in treating patients with advanced non-small cell lung cancer that blocks the air passages. However, these studies were terminated.