Tosedostat is a proprietary orally bioavailable inhibitor of the M1 family of aminopeptidases with potential antineoplastic activity. Tosedostat is converted intracellularly into a poorly membrane-permeable active metabolite (CHR-79888) which inhibits the M1 family of aminopeptidases, particularly puromycin-sensitive aminopeptidase (PuSA), and leukotriene A4 (LTA4) hydrolase; inhibition of these aminopeptidases in tumor cells may result in amino acid deprivation, inhibition of protein synthesis due to a decrease in the intracellular free amino acid pool, an increase in the level of the proapoptotic protein Noxa, and cell death. There are several ongoing Phase 2 cooperative group-sponsored trials and investigator-sponsored trials evaluating the clinical activity of Tosedostat in combination with standard agents in patients with acute myeloid leukemia (AML) or myelodysplastic syndrome (MDS).

Exisulind (tentative trade name Aptosyn) is an antineoplastic agent, which was originally developed by Cell Pathways. This drug is an inhibitor of phosphodiesterase (PDE) isozymes: PDE5 and PDE4. Inhibition of PDE5 appears to be pharmacologically relevant, which leads to increase cGMP and activate protein kinase G at doses that induce apoptosis, whereas cyclic AMP levels were not changed. Exisulind has been in phase III clinical trials for the treatment of Non-Small Cell Lung Cancer and for the treatment of polyps in patients who have familial adenomatous polyposis (Colorectal Cancer and Small Intestine Cancer). In addition, this drug was in phase II/III for the treatment of Prostate Cancer, however, there studies have been discontinued.

The BET-bromodomain inhibitor OTX015 (MK-8628) was initially developed by Mitsubishi Tanabe Pharma Corporation, but then was licensed by OncoEthix, privately held biotechnology company. OTX015 is a selective bromodomains: BRD2, BRD3, and BRD4 inhibitor and inhibits their binding to AcH4. Bromodomains have an important role in the targeting of chromatin-modifying enzymes to specific sites, including methyltransferases, HATs and transcription factors and regulate diverse biological processes from cell proliferation and differentiation to energy homeostasis and neurological processes. OTX015 has potent antiproliferative activity accompanied by c-MYC down-regulation in several tumor types, and has demonstrated synergism with the mTOR inhibitor everolimus in different models. Oral administration of OTX-015 markedly inhibited tumor growth and reduced tumor volume. OTX015 is currently in Phase 1b studies for the treatment of hematological malignancies and advanced solid tumors such as Triple Negative Breast Cancer, Non-small Cell Lung Cancer, Castrate-resistant Prostate Cancer (CRPC) and Pancreatic Ductal Adenocarcinoma. In addition, OTX015 was in phase II for the treatment of Glioblastoma Multiforme, but there were not detected clinical activity of the drug in the treatment populations and trial was closed.

Ralimetinib (LY2228820), a trisubstituted imidazole derivative, is a potent and selective, ATP-competitive inhibitor of the α- and β-isoforms of p38 mitogen-activated protein kinase. LY2228820 produced significant tumor growth delay in multiple in vivo cancer models (melanoma, non-small cell lung cancer, ovarian, glioma, myeloma, breast). Eli Lilly is developing ralimetinib for the treatment of cancer.

Plinabulin (formerly known as NPI-2358) is a potent microtubule-destabilizing agent that exerts its effect by binding to the colchicine-binding site of tubulin. Plinabulin projects its potent antitumor activity against a broad spectrum of tumor cell lines. This drug in combination with docetaxel is under development by BeyondSpring Pharmaceuticals in a worldwide Phase 3 clinical trial for non-small cell lung cancer. Pegfilgrastim is also in phase II clinical trial for the prevention of chemotherapy-induced neutropenia, where docetaxel, doxorubicin, and cyclophosphamide (TAC) were used as the chemotherapy. Plinabulin also possessed antitumor activity in animal models with multiple myeloma cancer cells, where the JNK protein appeared to be a primary target of plinabulin.

Sonolisib (PX-866) is a small-molecule inhibitor of the alpha, gamma, and delta isoforms of phosphoinositide 3-kinase (PI3K) with potential antineoplastic activity. Sonolisib inhibits the production of the secondary messenger phosphatidylinositol-3,4,5-trisphosphate (PIP3) and activation of the PI3K/Akt signaling pathway, which may result in inhibition of tumor cell growth and survival in susceptible tumor cell populations. Inhibition of the PI3K pathway with Sonolisib leads to inhibition of cell growth and decreased activation of downstream targets in GBM, both in vitro and in vivo, using U87–tumor-bearing mice, including Akt, S6, and mTOR. Sonolisib was in phase II clinical trials by Oncothyreon for the treatment of glioblastoma multiforme and castration-resistant prostate cancer (CRPC). It was in phase I/II clinical trials for the treatment of malignant melanoma, non-small cell lung cancer and Head and neck cancer. In clinical trials, Sonolisib was well tolerated, with common side effects being diarrhea, nausea, vomiting, and elevated liver enzymes. However, no recent development has been reported.

Mocetinostat is an rationally designed, orally available, Class 1-selective, small molecule, 2-aminobenzamide HDAC inhibitor with potential antineoplastic activity. Mocetinostat binds to and inhibits Class 1 isoforms of HDAC, specifically HDAC 1, 2 and 3, which may result in epigenetic changes in tumor cells and so tumor cell death; although the exact mechanism has yet to be defined, tumor cell death may occur through the induction of apoptosis, differentiation, cell cycle arrest, inhibition of DNA repair, upregulation of tumor suppressors, down regulation of growth factors, oxidative stress, and autophagy, among others. It is undergoing clinical trials for treatment of various cancers including bladder cancer, diffuse large B cell lymphoma, follicular lymphoma, myelodysplastic syndromes, non-small cell lung cancer. Fatigue, weight loss or anorexia were most common treatment-related adverse events.

Tozasertib, originally developed as VX-680 by Vertex (Cambridge, MA) and later renamed MK-0457 by Merck (Whitehouse Station, NY), was the first aurora kinase inhibitor to be tested in clinical trials. The drug, a pyrimidine derivative, has affinity for all aurora family members at nanomolar concentrations with inhibitory constant values (Ki(app)) of 0.6, 18, and 4.6 nM for aurora A, aurora B, and aurora C, respectively. Preclinical studies confirmed that tozasertib inhibited both aurora A and aurora B kinase activity, and activity has been reported against prostate, thyroid, ovarian, and oral squamous cancer cell lines. Upon treatment with tozasertib, cells accumulate with a 4N DNA content due to a failure of cytokinesis. This ultimately leads to apoptosis, preferentially in cells with a compromised p53 function. Tozasertib is an anticancer chemotherapeutic pan-aurora kinase (AurK) inhibitor that also inhibits FMS-like tyrosine kinase 3 (FLT3) and Abl. Tozasertib is currently in clinical trials as a potential treatment for acute lymphoblastic leukemia (ALL). In cellular models of cancer, tozasertib activates caspase-3 and PARP and decreases expression of HDAC, increasing apoptosis and inhibiting cell growth. In other cellular models, tozasertib inhibits cell proliferation and metastasis by blocking downstream ERK signaling and downregulating cdc25c and cyclin B. This compound also decreases tumor growth in an in vivo model of prostate cancer.

Seliciclib (CYC202, R-roscovitine) is a second-generation orally available cyclin-dependent kinases (CDKs) inhibitor that competes for ATP binding sites on these kinases. It is a direct inhibitor of cyclin CDK2/E, CDK2/A and it has inhibitory effects on cyclin H/CDK7, CDK5, and CDK9. CDKs are enzymes that are central to the process of cell division and cell cycle control and play pivotal roles in cancer cell growth and DNA damage repair. Seliciclib exerts an anti-proliferative effect via several key mechanisms: selective downregulation of proliferative and survival proteins and upregulation of p53, leading to growth arrest or apoptosis. The second one is decreasing phosphorylation of Rb and modulating E2F transcriptional activity leading to growth arrest or apoptosis. Seliciclib is currently in phase II clinical trial as a drug candidate for the treatment of Cushing's disease and as a potential therapeutic agent for the treatment of cystic fibrosis (CF). In addition, it is in Phase II trials for non-small cell lung cancer and nasopharyngeal carcinoma.

Canertinib or CI-1033 (N-[4-[N-(3-Chloro-4-fluorophenyl)amino]-7-[3-(4-morpholinyl)propoxy]quinazolin-6-yl]acrylamide) is a pan-erbB tyrosine kinase inhibitor. It selectively inhibits erbB1 (epidermal growth factor receptor), erbB2, erbB3, and erbB4 without inhibiting tyrosine kinase activity of receptors such as platelet-derived growth factor receptor, fibroblast growth factor receptor, and insulin receptor, even at high concentrations. Canertinib was under development by Pfizer Inc as a potential treatment for cancer.