Gimatecan is a topoisomerase I inhibitor that is presently tested in phase II of clinical trials for the treatment of different cancers: glioma, glioblastoma, epithelial ovarian cancer, fallopian tube or peritoneal cancer. The drug recieved orphan designation for the treatment of glioma.

Crenolanib is an orally active, highly selective, small molecule, next generation inhibitor of platelet-derived growth factor receptor (PDGFR) tyrosine kinase. Crenolanib, manufactured by Arog Pharmaceuticals in Dallas, is taken orally with chemotherapy. The compound is currently being evaluated for safety and efficacy in clinical trials for various types of cancer, including acute myeloid leukemia (AML), gastrointestinal stromal tumor (GIST), and glioma. Crenolanib is an orally bioavailable, selective small molecule inhibitor of type III tyrosine kinases with nanomolar potencies against platelet-derived growth factor receptors (PDGFR) (isoforms PDGFRα and PDGFRβ) and Fms-related tyrosine kinase 3 (FLT3). Besides PDGFR and FLT3, crenolanib does not inhibit any other known receptor tyrosine kinase (RTK) (e.g. VEGFR and FGFR) or any other serine/threonine kinase (e.g., Abl, Raf) at clinically achievable concentrations. Preclinical trials have shown Crenolanib to be active in inhibiting both wild-type and mutant FLT3. Crenolanib is cytotoxic to the FLT3/ITD-expressing leukemia cell lines Molm14 and MV411, with IC50s of 7 nM and 8 nM, respectively. In immunoblots, crenolanib inhibited phosphorylation of both the wild-type FLT3 receptor (in SEMK2 cells) and the FLT3/ITD receptor (in Molm14 cells) in culture medium with IC50s of 1-3 nM. Importantly, the IC50 of crenolanib against the D835Y mutated form of FLT3 was 8.8 nM in culture medium. Furthermore, crenolanib had cytotoxic activity against primary samples that were obtained from patients who had developed D835 mutations while receiving FLT3 TKIs. In vitro, the IC50 of crenolanib for inhibition of FLT3/ITD in plasma was found to be 34 nM, indicating a relatively low degree of plasma protein binding. From pharmacokinetic studies of crenolanib in solid tumor patients, steady state trough plasma levels of roughly 500 nM were found to be safe and tolerable, suggesting that crenolanib could potentially inhibit the target in vivo. Crenolanib has no significant activity against c-KIT, which may be an advantage in that myelosuppression can be avoided.1Furthermore, there was no evidence of QTc prolongation in patients treated with crenolanib. In summary, crenolanib offers a number of advantages over other FLT3 TKIs. Clinical trials of crenolanib in AML patients with FLT3 activating mutations are being planned.

Tesevatinib (EXEL-7647 or XL647) was optimized as an inhibitor of a spectrum of growth-promoting and angiogenic receptor tyrosine kinases (RTKs) to simultaneously block tumor growth and vascularization. In particular, Tesevatinib potently inhibits the EGF/ErbB2, VEGF, and ephrin RTK families. The drug is being developed by Kadmon Corporation under licence from Symphony Evolution (Symphony Capital Partners). Kadmon is developing tesevatinib for the treatment of autosomal polycystic kidney disease and solid cancers.

BLZ 945, an orally active antagonist of the colony-stimulating factor1 receptor (CSF1R), is being developed by Novartis and Celgene Corporation for the treatment of advanced solid tumors and tumor-induced osteolytic lesions in bone and skeletal-related events. Phase I/II development for solid tumors is underway in the US, Italy, Spain, and Singapore. Preclinical trials were ongoing for tumor-induced osteolysis in Europe and the US. However, no recent reports of development had been identified for this indication.

Altiratinib, a novel c-MET/TIE-2/VEGFR inhibitor, was able to effectively reduce tumor burden in vivo and block c-MET signaling, cell growth and migration. Altiratinib inhibits not only mechanisms of tumor initiation and progression, but also drug resistance mechanisms in the tumor and microenvironment. Altiratinib durably inhibits MET, both wild-type and mutated forms, in vitro and in vivo. Altiratinib exhibits properties amenable to oral administration and exhibits substantial blood-brain barrier penetration, an attribute of significance for eventual treatment of brain cancers and brain metastases. It is currently in Phase 1 clinical development for the treatment of solid tumors.

CC-115 is a recently identified inhibitor of the mammalian Target of Rapamycin Kinase (TORK) and DNA-Dependent Protein Kinase (DNA-PK). It is under investigation in phase II clinical trials for the treatment for Glioblastoma and in phase I trials for the treatment of prostate cancer, Ewing's, Osteosarcoma, Chronic Lymphocytic Leukemia and Squamous Cell Carcinoma of the Head and Neck.

Evofosfamide, also formerly known as TH-302, is an investigational hypoxia-activated prodrug and is used to target cancerous cells under hypoxic conditions, which is a feature possessed by multiple solid tumors including glioblastoma and pancreatic cancer. Within regions of tumor hypoxia, evofosfamide releases bromo isophosphoramide mustard (Br-IPM), a potent DNA alkylating agent that kills tumor cells by forming DNA crosslinks. Once activated in hypoxic tissues, Br-IPM can also diffuse into surrounding oxygenated regions of the tumor and kill cells there via a “bystander effect”. Because of its preferential activation in the targeted hypoxic regions of solid tumors, evofosfamide may be less likely to produce broad systemic toxicity seen with untargeted cytotoxic chemotherapies.

Withaferin A is one of the most bioactive phytoconstituents of Withania somnifera, a well-known herb in Ayurvedic medical tradition of India. Due to the lactonal steroid's potential to modulate multiple oncogenic pathways, Withaferin A has gained much attention as a possible anti-neoplastic agent. Systematic research on the evaluation of anticancer activities of withaferin A was started around the 1970s. Since then, a large number of studies have demonstrated the ability of withaferin A to suppress the in vivo growth of various human cancer cells’ xenograft tumors as well as experimentally induced carcinogenesis in different rodent models. It has being reported that withaferin-A reduced the growth of human prostate cancer (PC3) cells tumor xenograft in nude mice by blocking the tumor angiogenesis and inducing intratumoral apoptosis. According to this study, i.p. administration of withaferin-A caused regression of implanted tumor cells by decreasing the expression of angiogenesis marker CD31, inducing the expression of proapoptotic protein Bax, and activating caspase-3 via inhibition of nuclear factor-κB (NF-κB) signaling pathway. In a separate study, intratumoral administration of withaferin-A arrested PC3 cells’ xenograft tumor growth in mice by inducing tumor cell death via upregulation of prostate apoptosis response-4 (Par-4). Anticancer activity of withaferin-A has also being demonstrated for gynecological cancer, melanoma, thyroid, gastrointestinal and other types of cancer. Mechanistic basis of the anticancer effects of withaferin-A includes: (1) reinforcement of cellular antioxidant and/or detoxification system; (2) suppression of inflammatory pathways; (3) selective inhibition of tumor cell proliferation and induction of apoptosis; (4) suppression of tumor angiogenesis; (5) blockade of epithelial-to-mesenchymal transition (EMT), tumor invasion, and metastasis; (6) alteration of tumor cell metabolism; (7) immunomodulation; and (8) eradication of cancer stem cells.

p53 is a critical tumor suppressor and is the most frequently inactivated gene in human cancer. Inhibition of the interaction of p53 with its negative regulator MDM2 represents a promising clinical strategy to treat p53 wild-type tumors. AMG 232 is a potential best-in-class inhibitor of the MDM2-p53 interaction and is currently in clinical trials. Based on X-ray cocrystal structures a model of AMG 232 bound to MDM2 was developed. The model shows that the m-chlorophenyl, the p-chlorophenyl, and C-linked isopropyl fragments of AMG 232 bind to the Leu 26(p53), Trp 23(p53), and Phe 19(p53) pockets of MDM2, respectively. The carboxylic acid forms a salt bridge with His 96 and the isopropyl sulfone forms a novel interaction with the glycine shelf region of MDM2. AMG 232 in phase II in combination with trametinib and dabrafenib in subjects with metastatic melanoma; in phase I for the treatment of solid tumors, multiple myeloma and Acute Myeloid Leukemia.

LXR-623 is a is a highly selective and orally bioavailable synthetic agonist of Liver X receptors (LXR) alpha and beta that has shown promise in animal models of atherosclerosis. In nonhuman primates with normal lipid levels, LXR-623 significantly reduced total (50-55%) and LDL-cholesterol (LDLc) (70-77%) in a time- and dose-dependent manner and increased expression of the target genes ABCA1 and ABCG1 in peripheral blood cells of rats, mice and monkeys. LXR-623 demonstrated efficacy for reducing lesion progression in the murine LDLR(-/-) atherosclerosis model with no associated increase in hepatic lipogenesis either in this model or Syrian hamsters and displayed a unique and favorable pharmacological profile suggesting it may be suitable for evaluation in patients with atherosclerotic dyslipidemia. Results from a single ascending-dose study of the safety, pharmacokinetics, and pharmacodynamics of LXR-623 in healthy humans confirmed the effect of LXR-623 concentration on ABCA1 and ABCG1 expression. LXR-623 was absorbed rapidly with peak concentrations (Cmax) achieved at about 2 hours and increased Cmax and area under the concentration-time curve in a dose-proportional manner. The mean terminal disposition half-life was between 41 and 43 hours independently of dose. Central nervous system—related adverse events were observed at the 2 top doses tested. LXR-623 showed brain penetration and caused tumor regression in a glioblastoma (GBM) mouse model which characterize it as a potentially potent, highly-specific anti-GBM therapy.