Etanidazole (also known as Radinyl) is a 2-nitroimidazole with radiosensitizing properties. Etanidazole exerts its therapeutic action by depleting glutathione and inhibiting glutathione S-transferase, thus enhancing the anticancer effects of radiation therapy. Etanidazole was tested in Phase III clinical trials in patients with advanced head and neck cancer, however, its development was stopped. A fluorinated etanidazole (EF5) may also be useful as an imaging agent for identification of hypoxic, drug-resistant regions of primary tumors and metastases.

Motesanib (AMG 706), a novel nicotinamide, was identified as a potent, orally bioavailable inhibitor of the VEGFR1/Flt1, VEGFR2/kinase domain receptor/Flk-1, VEGFR3/Flt4 and Kit receptors. Motesanib was expected to reduce vascular permeability and blood flow in human tumours. A phase III trial of motesanib in combination with paclitaxel and carboplatin in non-squamous NSCLC has been terminated by Takeda and subsequently the development was discontinued. Motesanib has also been investigated up to phase II in breast, thyroid, colorectal and gastrointestinal stromal tumours. However, development has been discontinued in these indications.

Omtriptolide (previously known as PG490-88 or F60008), an immunosuppressant that has been shown to be the safe and potent antitumor agent and it has been approved entry into Phase I clinical trial for the treatment of prostate cancer in the USA. In addition, the drug is participating in phase I clinical trial for the treatment of myeloid leukemia. Experiments on animals have shown omtriptolide was highly effective in the prevention of murine graft-versus-host disease (GVHD). The immunosuppressive effect of the drug was mediated by inhibition of alloreactive T cell expansion through interleukin-2 production. However, this study was discontinued. Recently published article has shown omtriptolide possesses the potential as a prophylactic agent to prevent ischemia/reperfusion (I/R)-induced lung injury.

Hydroxytamoxifen (Afimoxifene) is an active metabolite of tamoxifen exerting estrogen receptor modulatory function. In addition, hydroxytamoxifen binds to regulates transcriptional activity of the estrogen-related receptor gamma. ASCEND Therapeutics, Inc. was developing TamoGel (4-hydroxytamoxifen gel) for a variety of estrogen-dependent conditions, including breast cancer, cyclic breast pain and gynecomastia.

Omtriptolide (previously known as PG490-88 or F60008), an immunosuppressant that has been shown to be the safe and potent antitumor agent and it has been approved entry into Phase I clinical trial for the treatment of prostate cancer in the USA. In addition, the drug is participating in phase I clinical trial for the treatment of myeloid leukemia. Experiments on animals have shown omtriptolide was highly effective in the prevention of murine graft-versus-host disease (GVHD). The immunosuppressive effect of the drug was mediated by inhibition of alloreactive T cell expansion through interleukin-2 production. However, this study was discontinued. Recently published article has shown omtriptolide possesses the potential as a prophylactic agent to prevent ischemia/reperfusion (I/R)-induced lung injury.

Brivanib is a pyrrolotriazine-based compound and an inhibitor of vascular endothelial growth factor receptor-2 (VEGFR-2) with potential antineoplastic activity. It specifically targets and strongly binds to human VEGFR-2, a tyrosine kinase receptor and pro-angiogenic growth factor expressed almost exclusively on vascular endothelial cells. Blockade of VEGFR-2 by this agent may lead to an inhibition of VEGF-stimulated endothelial cell migration and proliferation, thereby inhibiting tumor angiogenesis. Brivanib has a moderate potency compared to VEGFR-2 against VEGFR-1 and FGFR-1 as well. Brivanib is suggested to be efficient in treatment of hepatocellular carcinoma (HCC). As first-line and as second-line therapy brivanib demonstrated promising antitumor activity and a manageable safety profile in patients with advanced, unresectable HCC in phase II clinical trials. On 3 march 2011, orphan designation was granted by the European Commission to Bristol-Myers Squibb for brivanib alaninate for the treatment of hepatocellular carcinoma.[

Ravuconazole is a triazole with antifungal properties that inhibits cytochrome P450 sterol 14a-demethylase, an enzyme involved in sterol synthesis, resulting in lysis of the fungal cell wall and fungal cell death. It was investigated for the treatment of aspergillosis, candidiasis, and onychomycosis, but these studies were discontinued. Ravuconazole is now in phase II clinical trials to investigate efficacy in preventing fungal infections in patients undergoing chemotherapy and stem cell transplantation.

Ombrabulin is an experimental drug candidate discovered by Ajinomoto and further developed by Sanofi-Aventis for cancer treatment. Ombrabulin is a synthetic water-soluble analog of combretastatin A4, derived from the South African willow bush (Combretum caffrum), with potential vascular-disrupting and antineoplastic activities. Ombrabulin binds to the colchicine binding site of endothelial cell tubulin, inhibiting tubulin polymerization and inducing mitotic arrest and apoptosis in endothelial cells. As apoptotic endothelial cells detach from their substrate, tumor blood vessels collapse; the acute disruption of tumor blood flow may result in tumor necrosis. Ombrabulin has been used in trials studying the treatment of Sarcoma, Neoplasms, Solid Tumor, Neoplasms, Malignant, and Advanced Solid Tumors, among others. In January 2013, Sanofi said it discontinued development of Ombrabulin after disappointing results from phase III clinical trials.

Thiorphan is the first potent synthetic inhibitor of enkephalinase. Thiorphan displays antinociceptive activity after systemic administration. Thiorphan also inhibits to a lesser extent the widely distributed angiotensin-converting enzyme, a carboxydipeptidase implicated in blood pressure regulation. Thiorphan failed to potentiate allergen-induced airway responses in asthma. Thiorphan significantly reduced the castor oil-induced diarrhea in rats when administered intravenously but not when administered intracerebroventricularly. Racecadotril, via its active metabolite thiorphan, was consistently effective in animal models and patients with various forms of acute diarrhea by inhibiting pathologic (but not basal) secretion from the gut without changing gastro-intestinal transit time or motility.

AT7519M or AT7519, a small molecule inhibitor of cyclin-dependent kinases 1, 2, 4, 5, and 9, participated in phase II clinical trials in patients with relapsed or refractory chronic lymphocytic leukemia (CLL) and mantle cell lymphoma (MCL). As a result, in CLL, some patients had tumor reductions, but the objective response rate (ORR) was low. In MCL, activity was noted with ORR of 27%. In addition, AT7519M was studied in patients with previously treated multiple myeloma, to understand whether the drug alone or in combination with bortezomib were effective treatments. Recent experiments also have shown that AT7519 is a promising drug for the treatment of high-risk neuroblastoma patients with MYCN amplification. It is known, that MYCN-dependent neuroblastomas have low cure rates with current multimodal treatment.