JNJ-7706621, developed by Johnson & Johnson Pharmaceutical, is pan-CDK inhibitor with the highest potency on cyclin-dependent kinases: CDK1/2. Inhibition of CDK1 kinase activity, altered CDK1 phosphorylation status, and interference with downstream substrates such as retinoblastoma was also shown in human tumor cells following drug treatment. It also potently inhibits Aurora A/B and has no activity on Plk1 and Wee1. In human cancer cells, treatment with JNJ-7706621 inhibited cell growth independent of p53, retinoblastoma, or P-glycoprotein status; activated apoptosis; and reduced colony formation. At low concentrations, JNJ-7706621 slowed the growth of cells and at higher concentrations induced cytotoxicity. JNJ-7706621 is a unique inhibitor regulating cell cycle progression at multiple points, suggesting that it could be useful for cell cycle analysis and therapy of various cancers, including Ewing's sarcoma.

AS-605240 is a potent and selective phosphoinositide 3-kinase (PI3K) gamma inhibitor. It selectively inhibits PI3Kgamma enzymatic activity as well as PI3Kgamma-mediated signaling and chemotaxis in vitro and in vivo. It also has peripheral activity versus other PI3K isoforms. AS-605240 did not progress to clinical development although it had been described as a development candidate.

AZ-960 is a novel inhibitor of janus-associated kinases (JAKs) that exhibits a potent inhibition against janus kinase 2 (JAK2) with the value of inhibition constant of Ki of 0.45 nmol/L. It also exhibits a lesser inhibitory effects against other JAKs family members, including JAK1, JAK3 and TYK2 as well as other kinases, including TrkA, Aurora A and FAK, with 50% inhibition concentration IC50 of around 0.1 umol/L. In recent studies, AZ-960 demonstrates potential anti-cancer activity against adult T-cell leukemia (ATL), an aggressive malignancy of CD4+ T lymphocytes, by effectively inducing growth arrest and apoptosis in human T-cell lumphotropic virus type 1 (HTLV-1) infected T cells. AZ-960 potently inhibited the clonogenic growth and induced apoptosis of freshly isolated AML cells from patients in association with cleavage of caspase 3 and downregulation of anti-apoptotic Bcl-xL proteins.

Staurosporine is an alkaloid isolated from the culture broth of Streptomyces staurosporesa. It exerts antimicrobial, hypotensive, and cytotoxic activity. The main biological activity of staurosporine is the inhibition of protein kinases through the prevention of ATP binding to the kinase. This is achieved through the stronger affinity of staurosporine to the ATP-binding site on the kinase. Staurosporine is a prototypical ATP-competitive kinase inhibitor in that it binds to many kinases with high affinity, though with little selectivity. It is a potent, cell permeable protein kinase C inhibitor with an IC50 of 0.7 nM. At higher concentration (1-20 nM), staurosporine also inhibits other kinases such as PKA, PKG, CAMKII and Myosin light chain kinase (MLCK). At 50-100 nM, it is a functional neurotrophin agonist, promoting neurite outgrowth in neuroblastoma, pheochromocytoma and brain primary neuronal cultures. At 0.2- 1 uM, staurosporine induces cell apoptosis. Staurosporine is also a potent GSK-3β inhibitor with a reported IC50 value of 15 nM. In research, staurosporine is used to induce apoptosis. It has been found that one way in which staurosporine induces apoptosis is by activating caspase-3. Staurosporine was discovered to have biological activities ranging from anti-fungal to anti-hypertensive. The interest in these activities resulted in a large investigative effort in chemistry and biology and the discovery of the potential for anti-cancer treatment. Staurosporine induces apoptosis by multiple pathways and that the inhibition of more than one kinase is responsible for its potent activity. Because the mechanism of action of staurosporine is distinct from traditional anticancer drugs, this may warrant further preclinical evaluations of the antitumor potential of new staurosporine derivatives either alone or in combination with death ligands or conventional chemotherapeutic drugs.

Indolocarbazole GO-6976 inhibited the calcium-dependent protein kinase C (PKC) isozymes alpha and beta 1. As PKC is a central enzyme that modulates numerous biological functions GO-6976 is extensively used as a tool for studying the involvement of PKC in signal transduction pathways. GO6976 was originally synthesized by Goedecke (formerly a subsidiary of Warner-Lambert, now Pfizer) in Germany. Preclinical investigations carried out by Goedecke have been for the potential treatment of HIV infections. Preclinical research with GO 6976 had been conducted by Biomol Inc. and Calbiochem in the USA as a potential treatment for cancer. No further information has been available for the compound therefore it is assumed that development has been discontinued. In addition to GO-6976 inhibition of PKC, it was reported that GO-6976 also inhibits JAK 2 and FLT3 tyrosine kinases and non-kinase transmembrane guanylyl cyclase.

K-252a, a metabolite isolated from the culture broth of Nocardiopsis sp. K-252a, was found to exhibit an extremely potent inhibitory activity on protein kinase C. The IC50 value was 32.9 nM. K252a is a potent inhibitor of various protein kinases including Protein kinase A, Protein kinase C and Protein kinase G. It acts by competition with the ATP binding site with Ki values of 18-25 nM. K252a also acts as a specific and potent inhibitor (IC50 = 3 nM) of Trk receptors and thus selectively blocks the effects of nerve growth factor (NGF) on PC12 cells. At lower concentrations, K252a can act as a neuroprotective compound, promoting survival of primary neuronal cultures. This alkaloid induces apoptosis and cell cycle arrest by inhibiting Cdc2 and Cdc25.4 Recently, K252a was found to improve psoriasis in a SCID mouse-human skin model and to suppress referred mechanical hypersensitivity and neuropeptide up-regulation associated with acute pancreatitis.

PRT062607 (BIIB-057; P 50515 PRT-2607; PRT062607) is a highly specific and potent inhibitor of spleen tyrosine kinase (Syk). PRT062607 (BIIB-057) has a desirable pharmacokinetics profile and is capable of safely, potently, and selectively suppressing SYK kinase function in humans following once-daily oral dosing. The compound is being evaluated for the treatment of chronic inflammatory diseases; including rheumatoid arthritis, systemic lupus erythematosus, non-Hodgkin's lymphoma and chronic lymphocytic leukaemia. Phase I development is underway in the US and the UK for the treatment of patients with inflammation and cancer. Phase I development is also being conducted in rheumatoid arthritis and systemic lupus erythematosus, presumably in the US.