Alisertib (MLN8237) is an orally available selective aurora A kinase inhibitor developed by Takeda. Alisertib inhibited AAK over ABK with a selectivity of more than 200-fold in cells and produced a dose-dependent decrease in bipolar and aligned chromosomes in the HCT-116 xenograft model, a phenotype consistent with AAK inhibition. Alisertib inhibited proliferation of human tumor cell lines in vitro and produced tumor growth inhibition in solid tumor xenograft models and regressions in in vivo lymphoma models. It is currently in phase II clinical trials for acute myeloid leukaemia; B cell lymphoma; brain cancer; mesothelioma; prostate cancer; small cell lung cancer.

Volasertib (BI 6727), a dihydropteridinone derivative, is a small-molecule cell cycle inhibitor of polo-like kinase-1 (PLK-1). Volasertib induces G2-M arrest and induction of apoptosis in cancer cells and potently inhibits tumor growth in xenograft models. Boehringer Ingelheim is developing intravenously administered volasertib for the treatment of acute myeloid leukaemia (AML), myelodysplastic syndromes (MDS), chronic myelomonocytic leukaemia (CMML), non-small cell lung cancer, urogenital cancer, ovarian cancer and solid tumours.

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.

Veliparib (ABT-888) is a potent inhibitor of PARP, has good oral bioavailability, can cross the blood-brain barrier, and potentiates temozolomide, platinums, cyclophosphamide, and radiation in syngeneic and xenograft tumor models. AbbVie is developing veliparib for the treatment of cancers. Clinical trials are underway worldwide, investigating veliparib primarily as part of a combination therapy in oncology indications such as brain, colorectal, melanoma, ovarian, prostate and pancreatic cancers.

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.

Methoxyamine (TRC102) is an orally bioavailable small molecule with potential adjuvant activity, that may potentiate the antitumor activity of alkylating agents. Methoxyamine covalently binds to apurinic/apyrimidinic (AP) DNA damage sites and inhibits base excision repair (BER) that causes topoisomerase II-dependent irreversible strand breaks and apoptosis. Methoxyamine is currently being studied in multiple Phase 1 and Phase 2 clinical trials sponsored by the National Cancer Institute or Case Comprehensive Cancer Center.

Iniparib (BSI-201 or 4-iodo-3-nitrosobenzamide) inactivated poly(ADP-ribose) polymerase by zinc ejection from the first zinc finger of this nuclear protein. Iniparib, either alone or in combination with chemotherapy, had significant antitumor activity in preclinical studies in vitro and in vivo. In June 2013, Sanofi dropped the drug after it failed in a phase III trial of patients with squamous non–small-cell lung cancer and a phase II trial in platinum-resistant ovarian cancer.

Fosbretabulin (Combretastatin A4 phosphate, CA4P) is the lead compound of a relatively new class of agents termed vascular disrupting agents that target existing tumor blood vessels. Rapid tumor blood flow shutdown has been demonstrated in preclinical models and patients by various techniques such as dynamic contrast-enhanced MRI, perfusion computed tomography and PET scans following CA4P infusion. CA4P typically induces rapid tumor necrosis in the center of the tumor and leaves a rim of viable cells in the periphery. In oncology, CA4P does not appear to be that active by itself, but may be more efficacious when combined with chemotherapy, antiangiogenic therapy and radiation therapy. Combretastatin was initially isolated from the root bark of the South African Bush willow Combretum caffrum in 1982 by Pettit and colleagues at the Arizona State University (AZ, USA). Combretastatin A4 phosphate binds avidly to tubulin at the colchicine-binding site to inhibit microtubule assembly and destabilize the cytoskeleton. CA4P is a tubulin-binding agent that binds at or near the colchicine binding site of β-tubulin (Kd = 0.40 uM), inhibits tubulin assembly with IC50 of 2.4 uM. Fosbretabulin has orphan drug status in the EU and the US for the treatment of ATC (Anaplastic Thyroid Cancer). Later the development of this drug was discontinued.

Zibotentan (ZD4054) is a potent and specific orally available endothelin A (ETA) receptor antagonist, with no measurable affinity for endothelin B receptor. Activation of the ETA receptor by ET-1 has emerged as an important factor promoting tumor cell proliferation, survival, angiogenesis, migration, invasion, and metastasis in several tumor types. Zibotentan inhibits endothelin-mediated mechanisms that promote tumour cell proliferation. Zibotentan was being developed by AstraZeneca as treatment for heart failure, hormone resistant prostate cancer and other cancers including non-small cell lung, ovarian and breast cancer. However, following disappointing results from a phase III trial in patients with advanced prostate cancer, AstraZeneca decided to discontinue the development of zibotentan as a potential treatment for cancer. AstraZeneca undertook preclinical studies in the UK with zibotentan to investigate its potential as a treatment for heart failure. However, development for this indication has been discontinued.

Pfizer's CP-547632 is a selective inhibitor of VEGFR-2 tyrosine kinase that was discovered during Pfizer's collaboration with OSI Pharmaceuticals. CP-547632, was identified as a potent inhibitor of the VEGFR-2 and basic fibroblast growth factor (FGF) kinases (IC(50) = 11 and 9 nM, respectively). It is selective relative to epidermal growth factor receptor, platelet-derived growth factor beta, and other related TKs. It also inhibits VEGF-stimulated autophosphorylation of VEGFR-2 in a whole cell assay with an IC(50) value of 6 nM. After oral administration of CP-547632 to mice bearing NIH3T3/H-ras tumors, VEGFR-2 phosphorylation in tumors was inhibited in a dose-dependent fashion (EC(50) = 590 ng/ml). CP-547,632 is a well-tolerated, orally-bioavailable inhibitor presently under clinical investigation for the treatment of human malignancies. CP-547632 is in phase I for the treatment of diabetic retinopathy and age-related macular degeneration.