Tanespimycin (17-allylamino-17-demethoxygeldanamycin, 17-AAG) is a synthetic analogue of geldanamycin, an antibiotic first purified in 1970 from Streptomyces hygroscopicus. Tanespimycin is an Hsp90 inhibitor that has demonstrated the potential to disrupt the activity of multiple oncogenes and cell signaling pathways implicated in tumor growth, including HER2, a key pathway in breast cancer. Tanespimycin was being under development by Kosan Biosciences. It was in phase 3 clinical development with bortezomib for the treatment of multiple myeloma (MM). However, in 2010 the company halted development of tanespimycin, during late-stage clinical trials as a potential treatment for multiple myeloma. While no definitive explanation was given, it has been suggested that Bristol-Myers Squibb halted development over concerns of the financial feasibility of tanespimycin development given the 2014 expiry of the patent on this compound, and the relative expense of manufacture.

The monoterpene perillyl alcohol (POH) is a naturally occurring compound derived from citrus fruits, mint, and herbs. It exhibited chemotherapeutic potential against various malignant tumors in preclinical models and was being tested in clinical trials in patients with refractory advanced cancers. POH was formulated in soft gelatine capsules and orally administered to cancer patients several times a day on a continuous basis. However, such clinical trials in humans yielded disappointing results, also because of the large number of capsules that had to be swallowed caused hard-to-tolerate intestinal side effects, causing many patients to withdraw from treatment due to unrelenting nausea, fatigue, and vomiting. The clinical trials in Brazil have explored intranasal POH delivery as an alternative to circumvent the toxic limitations of oral administration. In these trials, patients with recurrent malignant gliomas were given comparatively small doses of POH via simple inhalation through the nose. Results from these studies showed, that this type of long-term, daily chemotherapy was well tolerated and effective. The precise mechanism of action is still undetermined, but it is known, that perillyl alcohol plays an important role in the process of hepatoma cell invasion and migration via decreasing the activity of Notch signaling pathway and increasing E-cadherin expression regulated by Snail. Another possible mechanism is included inhibition of Na/K-ATPase (NKA). The NKA α1 subunit is known to be superexpresses in glioblastoma cells (GBM) and POH acts in signaling cascades associated with NKA can control cell proliferation and/or cellular death.

Pilaralisib (XL147, SAR245408) is a potent and highly selective inhibitor of class I phosphatidylinositol 3-kinase (PI3K) (α, β, γ, and δ). In cellular assays, XL147 inhibits the formation of PIP3 in the membrane, and inhibits phosphorylation of AKT, p70S6K, and S6 in multiple tumor cell lines with diverse genetic alterations affecting the PI3K pathway. In a panel of tumor cell lines, XL147 inhibits proliferation with a wide range of potencies, with evidence of an impact of genotype on sensitivity. Repeat-dose administration of XL147 results in significant tumor growth inhibition in multiple human xenograft models in nude mice. Pilaralisib, was being developed by Exelixis and its licensee, Sanofi (formerly sanofi-aventis), for the treatment of solid tumours. However, the product was not listed on Sanofi's early stage pipeline as of end of July 2015 and there have been no recent reports on development identified.

Indole-3-carbinol (I3C), a common phytochemical in cruciferous vegetables, and its condensation product, 3,3'-diindolylmethane (DIM) exert several biological activities on cellular and molecular levels, which contribute to their well-recognized chemoprevention potential. ndole-3-carbinol is used for prevention of breast cancer, colon cancer, and other types of cancer. The National Institutes of Health (NIH) has reviewed indole-3-carbinol as a possible cancer preventive agent and is now sponsoring clinical research for breast cancer prevention. Indole-3-carbinol is also used for fibromyalgia, tumors inside the voice box (laryngeal papillomatosis) caused by a virus, tumors inside the respiratory tract (respiratory papillomatosis) caused by a virus, abnormal cell growth in the cervix (cervical dysplasia), and systemic lupus erythematosus (SLE). Indole-3-carbinol scavenges free radicals and induces various hepatic cytochrome P450 monooxygenases. Specifically, this agent induces the hepatic monooxygenase cytochrome P4501A1 (CYP1A1), resulting in increased 2-hydroxylation of estrogens and increased production of the chemoprotective estrogen 2-hydroxyestrone. Accumulating evidence indicates that the antitumor activity of indole-3- carbinol is attributable to its ability to interfere with multiple oncogenic signaling pathways governing cell cycle progression, survival, invasion, and other aggressive phenotypes of cancer cells. Reported signaling targets of indole-3- carbinol in various cancer cell lines include EGFR/Src, Akt/NF-B, stress responses, elastase, and Rho kinase. Moreover, indole-3-carbinol functions as a negative regulator of estrogen action in hormonesensitive cancer cells through the inhibition of estrogen receptor (ER)-alpha signaling and/or induction of cytochrome P-450-mediated estrogen metabolism, suggesting its clinical use in hormone-sensitive cancers.

Epothilone D (KOS-862 or BMS-241027) is an intermediary obtained in the synthesis of members of the epothilone family and is a small-molecule microtubule stabilizer. It was investigated in Phase II trials in colorectal, metastatic breast and non-small-cell lung cancers. However, development was discontinued in 2007 in favor of a second-generation analog with a better safety profile. This drug also was studied for the treatment of Alzheimer's disease. The study ended in October 2013, and evaluation of epothilone D for Alzheimer's disease was subsequently discontinued. The mechanism by which epothilones induce microtubule polymerization appears to be similar to that of paclitaxel, in that epothilones compete with paclitaxel for binding to microtubules and suppress microtubule dynamics in a manner similar to that of paclitaxel.

Diosgenin is a major bioactive constituent of various edible pulses and roots, well characterized in the seeds of fenugreek as well as in the root tubers of wild yams. The findings from pre-clinical and mechanistic studies strongly implicate the use of diosgenin as a novel multi-target based chemo preventive or therapeutic agent against several chronic diseases. Diosgenin has been shown to increase cholesterol secretion fiveto seven-fold in the bile of rats without altering the output of bile salts and phospholipids (Kosters et al., 2005; Nervi et al., 1988; Nibbering et al., 2001). Recently, it was shown that the biliary cholesterol secretion stimulated by diosgenin and leading to fecal cholesterol excretion is independent of intestinal cholesterol absorption. The anti-cancer effects of diosgenin in vitro through different mechanisms was investigated and was shown that it could use in the treatment Colon cancer, breast cancer, prostate cancer and some others. Also was investigates the effect of diosgenin on hepatitis C virus (HCV) replication and was shown that compound can inhibits HCV replication at low µM concentrations. Diosgenin was able to protect the kidney from morphological changes associated with ovariectomy. The mechanism is responsible for this protection was the conversion of diosgenin to progesterone. The extensive pre-clinical and clinical research should be carried out prior to advocating the safe and efficacious use of diosgenin and diosgenin-rich plant extracts against the prevention and control of diseases.

Fenretinide (4-HPR) is an orally-active synthetic phenylretinamide analogue of retinol (vitamin A) with potential antineoplastic and chemopreventive activities. Fenretinide binds to and activates retinoic acid receptors (RARs), thereby inducing cell differentiation and apoptosis in some tumor cell types. This agent also inhibits tumor growth by modulating angiogenesis-associated growth factors and their receptors and exhibits retinoid receptor-independent apoptotic properties. Phase III clinical trial data has suggested that fenretinide reduces breast cancer relapse in pre-menopausal women. Fenretinide is the most studied retinoid in breast cancer chemoprevention clinical trials due to its selective accumulation in breast tissue and its favorable toxicological profile. This agent showed a significative reduction of the incidence of second breast tumors in premenopausal women confirmed after 15-year followups. Fenretinide, a drug being developed by Sirion Therapeutics, slowed the progression of advanced dry age-related macular degeneration (AMD) by 45 percent for people receiving a higher dose of the treatment in a Phase II clinical trial. Sirion has been granted a Fast Track designation for the treatment by the FDA. Fenretinide is in phase II clinical trials for the treatment of B-cell lymphoma, chronic lymphocytic leukemia. It is also in phase I clinical trials for the treatment of cystic fibrosis.

Amonafide L-malate (AS1413, Xanafide) is a DNA intercalator and topoisomerase II inhibitor that induces apoptosis by disrupting chromatin organisation independently of ATP. This is different from classical topoisomerase II inhibitors which induce apoptosis by causing extensive DNA damage. Amonafide L-malate is also able to evade P-glycoprotein and related transporters that contribute to multi-drug resistance. AS1413 had orphan drug status in both the U.S. and the E.U. for the treatment of AML and also received Fast Track status from the U.S. FDA for the treatment of secondary AML. Amonafide L-malate was originated by Xanthus Pharmaceuticals. It was added to Antisoma's pipeline through the acquisition of Xanthus Pharmaceuticals, Inc. in June 2008. Antisoma discontinued development of Amonafide L-malate after data from the open-label, international Phase III ACCEDE trial in over 420 patients showed that 600 mg/m 2 IV amonafide for 5 days plus cytarabine missed the primary endpoint of significantly improving initial remission rate, defined as the proportion of patients who achieve CR or CRi, vs. daunorubicin plus cytarabine.

GGTI-2418, also known as PTX100, is a synthetic peptidomimetic inhibitor of geranylgeranyltransferase I (GGTase I) that appears to induce apoptosis by downregulating several pivotal oncogenic and tumor survival pathways. In preclinical studies, GGTI-2418 has been shown to cause significant breast tumor regression in ErbB2 transgenic mice model. GGTI-2418 was the first GGTase I inhibitor to enter clinical development in early 2009. Phase I clinical trials early results demonstrated that ~30% of patients with advanced solid tumors had stable disease following GGTI-2418 therapy, the compound was well-tolerated and had minimal toxicity. However, the Phase I trial of GGTI-2418 has been stopped due to its lack of efficacy in patients. In February 2015 Prescient Therapeutics in-licensed the p27 biomarker for use as a companion diagnostic. Patients with low levels of p27 are more likely to respond to GGTI-2418 therapy.

SNX-2112, a novel 2-aminobenzamide inhibitor of heat shock protein 90 (Hsp90) was discovered by Serenex. This drug was investigated for treatment of different cancer cell lines, including hepatocellular carcinoma cells, breast cancer cells and in combination with 5-fluorouracil in esophageal cancer. However, subsequent development has been discontinued due to ocular toxicity as identified in a phase I study.