Vatalanib a potent oral tyrosine kinase inhibitor with a selective range of molecular targets, has been extensively investigated and has shown promising results in patients with solid tumors in early trials. Vatalanib selectively inhibits the tyrosine kinase domains of vascular endothelial growth factor (VEGF) receptor tyrosine kinases (important enzymes in the formation of new blood vessels that contribute to tumor growth and metastasis), platelet-derived growth factor (PDGF) receptor, and c-KIT. The adverse effects of vatalanib appear similar to those of other VEGF inhibitors. In the CONFIRM trials, the most common side effects were high blood pressure, gastrointestinal upset (diarrhea, nausea, and vomiting), fatigue, and dizziness.

Ditercalinium is the antineoplastic agent. Ditercalinium itself is not a natural product, however, it is derived from the natural product 5,11-dimethyl-6H-pyrido-[4,3- b]carbazole (ellipticine) that was isolated in 1959. It is a rare example of a noncovalent DNA-binding ligand that forms bisintercalation complexes via the major groove of the double helix. Ditercalinium selectively recognizes certain GC-rich sequences in DNA. It preferentialy binds with antiparallel quadruplex sequence d(AG(3)[T(2)AG(3)](3)). Ditercalinium chloride can deplete mitochondrial DNA in both mouse and human cells. Ditercalinium chloride inhibits human DNA polymerase gamma activity as efficiently as does ethidium bromide. Ethidium bromide distributes diffusely in the mitochondria of HeLa cells, while ditercalinium chloride distributes granularly and hence may be strongly associated with mitochondrial DNA.

Canfosfamide is a modified glutathione analogue and nitrogen mustard prodrug, with potential antineoplastic activity. Canfosfamide is selectively activated by glutathione S-transferase P1-1 an enzyme that is over-expressed in many human cancers including ovarian cancer. GST P1-1-mediated cleavage leads to an active cytotoxic phosphorodiamidate alkylating metabolite that forms covalent linkages with nucleophilic centers in tumor cell DNA, which may induce a cellular stress response and cytotoxicity, and decrease tumor cell proliferation. Preclinical studies showed that canfosfamide inhibited the growth and was cytotoxic to a wide range of established cancer cell lines including those derived from ovarian cancer (OVCAR3, HEY, SK-OV-3). Canfosfamide treatment inhibited cancer cell proliferation and induced apoptosis through the activation of the cellular stress response kinase pathway. The cytotoxic activity of canfosfamide correlated with the expression of GST P1-1. Cancer cells in which GST expression levels were increased by transfection with the GST P1-1 gene, were more sensitive to the cytotoxic effects of canfosfamide than the parental cell lines Canfosfamide in combination with pegylated liposomal doxorubicin is well tolerated and active in platinum and paclitaxel refractory or resistant ovarian cancer.

Amustaline (S-303) is a quinacrine mustard compound with potential antineoplastic activity. Amustaline binds to, intercalates and crosslinks DNA and RNA. This agent is mainly used for ex vivo purposes, specifically for the inactivation of pathogens such as viruses, protozoa and bacteria in red blood cells (RBCs). When S-303 is added to red blood cells, the compound rapidly passes through membranes, including those of cells and viral envelopes, due to its amphipathic character, and intercalates into helical regions of the nucleic acids of pathogens and white blood cells. TERCEPTTMBlood System usingamustaline (S-303) and glutathione (GSH) was able to inactivate high levels of DENV and ZIKV in RBCs. S-303 system has been shown to effectively inactivate a broad spectrum of pathogens, while maintaining RBC quality.

Motexafin gadolinium is a novel, MRI-detectable, an anticancer agent that enhances the cytotoxic potential of radiation therapy through several mechanisms, including depleting intracellular reducing metabolites that are necessary for repairing the oxidative damage induced by irradiation. Motexafin gadolinium catalyzes the oxidation of intracellular reducing metabolites such as ascorbate, glutathione, nicotinamide adenine dinucleotide phosphate, and protein thiols, generating reactive oxygen species in a process known as futile redox cycling. The depletion (through oxidation) of these reducing metabolites removes the substrate necessary in a cell to repair oxidative damage induced by radiation and, left unrepaired, such radiation-induced oxidative DNA damage is converted into lethal double-stranded breaks. Motexafin gadolinium has tumor-specific uptake, normal tissue sparing, and tolerable and reversible toxicities in clinical trials. Motexafin gadolinium use in conjunction with whole-brain radiation therapy (WBRT) has demonstrated an improvement in neurocognitive decline, neurologic progression, and quality of life in patients with brain metastases from Non-small-cell lung carcinoma. Motexafin gadolinium use in conjunction with radiosurgery and whole brain radiation therapy in the setting of brain metastases is currently being studied, as is Motexafin gadolinium with radiation and temozolomide in patients with glioblastoma multiforme.

Mivobulin is a synthetic water-soluble colchicine analog with the broad antitumor activity that competitively binds tubulin at the colchicine-binding site and inhibits tubulin polymerization. Cancer cells exposed to Mivobulin isethionate accumulate in the M phase of the cell cycle and subsequently die. Preclinical studies have demonstrated that Mivobulin isethionate is able to cross the blood-brain barrier. Importantly, Mivobulin isethionate demonstrated significant antitumor activity in a broad spectrum of murine and human tumor models that were cross-resistant to vincristine, cisplatin, vinblastine, navelbine, and doxorubicin and in tumor cell lines exhibiting multidrug resistance owing to P-glycoprotein overexpression. In animal studies, the activity of Mivobulin isethionate was largely independent of the route of drug administration but favored a prolonged treatment schedule. Unfortunately, in clinical trials, Mivobulin fail to demonstrate the significant activity

Prospidium is a diazoniadispiro(5.2.5.2)hexadecane derivative patented by All-Union Scientific-Research Chemical-Pharmaceutical Institute as an antitumor agent that does not inhibit hematopoiesis. In preclinical models, The injection of Prospidium to thyroidectomized and hypophysectomized rats inhibited tumor growth to a greater extent than in intact rats. Larynx and lung cancer, lymphogranulomatosis, leucosis, etc. can be successfully treated with Prospidium at doses of 60-120 mg daily.

Amuvatinib (formerly known as MP470) is an oral multi-targeted tyrosine kinase inhibitor, which play critical roles in transducing growth signals to cancer cells. It suppresses c-MET, c-RET and the mutant forms of cKIT, PDGFR and FLT3. It also disrupts DNA repair likely through suppression of homologous recombination protein Rad51, an important survival pathway in many human cancers. In vitro and in vivo data have demonstrated amuvatinib synergy with DNA damaging agents including etoposide and doxorubicin. Overall, in the amuvatinib clinical development program, over 200 subjects were exposed to at least one dose of amuvatinib. In the Phase 1b clinical study in combination with carboplatin and etoposide, responses in small cell lung cancer (SCLC), neuroendocrine as well as other tumor types were observed. Human pharmacokinetic data suggest that co-administration of amuvatinib did not alter exposures of standard of care agents including carboplatin, etoposide, doxorubicin, paclitaxel, topotecan or erlotinib as measured by overall exposure. In the first-in-human study, durable clinical benefit was observed in the gastrointestinal stromal tumors (GIST) with modulation of Rad51 observed in skin punch biopsies. In clinical trials, amuvatinib has demonstrated a wide therapeutic window and shows minimal toxicity in the expected therapeutic dose range, despite suppressing several signaling pathways within cells. However, in spite of this, this drug was discontinued, because it was not pre-specified primary endpoints in the clinical proof of concept (cPOC) stage. But the combination of MP470 and Erlotinib, which target the HER family/PI3K/Akt pathway may represent a novel therapeutic strategy for prostate cancer.

Puromycin dihydrochloride belongs to the aminonucleoside family of antibiotics and is isolated from Streptomyces alboniger. Since the partial structure of this antibiotic showed it to be a purine derivative, puromycin was assigned as its generic name. Puromycin is a broad spectrum antibiotic and antibacterial agent. It is active against Gram-positive microorganisms, less active against acid-fast bacilli, and weakly active against Gram-negative microorganisms. It acts very quickly and can kill 99% of the cells within 2 days. It also exhibits antitumor activity in studies on brain tumor cells. Puromycin is a protein synthesis inhibitor that causes premature chain termination by acting as an analog of the 3’-terminal end of aminoacyl-tRNA. It has been used to study transcriptional regulatory mechanisms that control the sequential and coordinate expression of genes during cell differentiation.

Banoxantrone (formally known as AQ4N), a bioreductive drug that is irreversibly converted to AQ4, a stable DNA affinic cytotoxic compound. Banoxantrone is activated by haem-containing reductases such as inducible nitric oxide synthase (iNOS). In hypoxic cells, AQ4N is reduced to the topoisomerase II inhibitor AQ4. By inhibition of topoisomerase II within these hypoxic areas, AQ4N has been shown to sensitize tumors to existing chemo- and radiotherapy treatments. Novacea, the company which was responsible for clinical trials for banoxantrone had decided to scale back on its clinical development, including discontinuing the clinical trial in acute lymphoblastic leukemia and delaying the planned clinical trial in B-cell lymphoma. The company decided to continue enrollment in an ongoing Phase 1b/2a clinical trial in patients with glioblastoma multiforme. However, further information about these clinical trials are not available. Some recent experiments have shown that targeting hypoxic tumors with high levels of iNOS with a combination of AQ4N and radiotherapy could be a useful clinical therapeutic strategy.