Trequinsin is a potent PDE3 inhibitor that inhibits PDE4 and PDE2 at higher concentrations. Trequinsin can block platelet aggregation and also inhibit tissue factor expression in human endothelial cells. Trequinsin can enhance cellular cAMP content, forskolin-induced cAMP synthesis, and renin release in cells.

Flumatinib (HHGV678) is an orally bioavailable antineoplastic tyrosine kinase inhibitor. Flumatinib inhibits the wild-type forms of Bcr-Abl, platelet-derived growth factor receptor (PDGFR) and mast/stem cell growth factor receptor (SCFR; c-Kit) and forms of these proteins with certain point mutations. Flumatinib was extensively metabolized after oral administration, and the major metabolic pathways observed were amide hydrolysis, demethylation, oxidation, and glucuronide conjugation. It is in phase III clinical trials for the treatment of Chronic myeloid leukemia (in China).

Ricolinostat is a selective inhibitor of HDAC6 with IC50 value of 4.7 nM. Ricolinostat demonstrated good anti-proliferative activity on different cell lines and clinical models of cancer. The drug is being tested in phase I/II for the treatment of multiple myeloma and lymphoid malignancies and in phase I in patients with breast cancer, gynecological cancer, cholangiocarcinoma, recurrent chronic lymphoid leukemia.

Vedroprevir, or GS-9451, is a potent inhibitor of the HCV NS3 protease (Box 1). NS3 is a serine protease that cleaves the HCV polyprotein and helps generate the viral replication complex. Through binding NS3, vedroprevir halts the assembly of the viral replication complex, thus interfering with the assembly and release of viral particles. Vedroprevir is a potent inhibitor of NS3 protease with high selectivity against off-target proteases. It has rapid association kinetics and slow dissociation kinetics. Preclinical studies of vedroprevir showed high oral bioavailability in rats, dogs, and monkeys. Preclinical studies of vedroprevir demonstrated potent NS3 inhibition using laboratory strains as well as patient-derived NS3 protease gene isolates. In a phase I, randomized trial of vedroprevir monotherapy, doses of 200 and 400 mg/day yielded median maximal HCV RNA reductions of −3.2 log10 in genotype 1a patients and −3.5 log10 in genotype 1b patients. Significantly less activity was seen against genotype 2a HCV when compared to genotype 1. Vedroprevir was not listed on the Gilead Sciences pipeline in its 2014 annual report and appears to have been discontinued for the once-daily treatment of Hepatitis C.

Rigosertib sodium (ON 01910.Na) is a small molecule inhibitor of critical pathways important in the growth and survival of cancer cells, being developed by Onconova Therapeutics ("Onconova") for the treatment of hematologic malignancies and solid tumors. Rigosertib (ON-01910) is a non-ATP-competitive inhibitor of PLK1 with IC50 of 9 nM in a cell-free assay. It shows 30-fold greater selectivity against Plk2 and no activity to Plk3. Extensive Phase I and Phase II studies with rigosertib have been conducted at leading institutions in the U.S. and abroad in more than 450 patients with solid tumors and hematological cancers, including MDS and AML. MDS and AML are blood disorders widely recognized as difficult to manage, with limited therapeutic options available for patients, especially those with drug-resistant disease. The multi-site Phase III ONTIME trial in MDS patients is under a Special Protocol Assessment (SPA) from the U.S. FDA and is being supported by an award from the Therapeutics Acceleration Program (TAP) of the Leukemia and Lymphoma Society (LLS). FDA has granted Orphan Drug Designation for the use of rigosertib in MDS. The clinical program in solid tumors is also advancing with initiation of the Phase II/III combination ONTRAC trial (ON 01910.Na TRial in Patients with Advanced Pancreatic Cancer) and Phase II single agent trial in ovarian cancer. In Japan, SymBio is developing rigosertib for the treatment of refractory/relapsed HR-MDS (IV form) and first-line LR-MDS (oral form).

Apitolisib, a dual inhibitor of mTOR and phosphatidylinositol 3-kinase (PI3K), was being developed by Roche and Genentech as an orally administered therapy of cancer. Apitolisib is a selective, potent, orally bioavailable inhibitor of Class I PI3 kinase (PI3K) and mTOR kinase (TORC1/2) with excellent pharmacokinetic and pharmaceutical properties. Apitolisib displayed excellent potency against class I PI3K isoforms (IC50 PI3K-α, β, δ and γ = 4.8, 27, 6.7 and 14 nM) and mTOR kinase (IC50 = 17 nM) and selectivity against a large panel of other kinases. Apitolisib is in phase II trials by Genentech for the treatment of breast cancer, prostate cancer, endometrium cancer, kidney cancer. However, no recent development has been reported. It is also in phase I trials by Genentech for the treatment of non-Hodgkin's lymphoma.

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.

P276-00 (also known as riviciclib) is a novel, potent, small-molecule, flavone-derived inhibitor of cyclin-dependent kinases (Cdk), Cdk 4 D1, Cdk1 B, and Cdk9 T, with potent cytotoxic effects against chemosensitive and chemoresistant cancer cell lines. P276-00 was in phase II clinical trial for the treatment mantle cell lymphoma, but that study was terminated based on interim results and all subjects were off study at that time. Although, there were not the major safety or tolerability concerns. However, this drug successfully passed phase II clinical trial for the treatment Melanoma, squamous cell carcinoma of head and neck, malignant melanoma and in combination with Gemcitabine in the treatment of advanced pancreatic cancer.