Advances towards the development of ATP-competitive small-molecule inhibitors of the insulin-like growth factor receptor (IGF-IR)

Kinase Inhibitors in the Treatment of Ovarian Cancer: Current State and Future Promises

Ovarian cancer is the deadliest gynecological cancer, the high-grade serous ovarian carcinoma (HGSC) being its most common and most aggressive form. Despite the latest therapeutical advancements following the introduction of vascular endothelial growth factor receptor (VEGFR) targeting angiogenesis inhibitors and poly-ADP-ribose-polymerase (PARP) inhibitors to supplement the standard platinum- and taxane-based chemotherapy, the expected overall survival of HGSC patients has not improved significantly from the five-year rate of 42%. This calls for the development and testing of more efficient treatment options. Many oncogenic kinase-signaling pathways are dysregulated in HGSC. Since small-molecule kinase inhibitors have revolutionized the treatment of many solid cancers due to the generality of the increased activation of protein kinases in carcinomas, it is reasonable to evaluate their potential against HGSC. Here, we present the latest concluded and on-going clinical trials on kinase inhibitors in HGSC, as well as the recent work concerning ovarian cancer patient organoids and xenograft models. We discuss the potential of kinase inhibitors as personalized treatments, which would require comprehensive assessment of the biological mechanisms underlying tumor spread and chemoresistance in individual patients, and their connection to tumor genome and transcriptome to establish identifiable subgroups of patients who are most likely to benefit from a given therapy.

Theoretical and computational studies of peptides and receptors of the insulin family

Synergistic interactions among peptides and receptors of the insulin family are required for glucose homeostasis, normal cellular growth and development, proliferation, differentiation and other metabolic processes. The peptides of the insulin family are disulfide-linked single or dual-chain proteins, while receptors are ligand-activated transmembrane glycoproteins of the receptor tyrosine kinase (RTK) superfamily. Binding of ligands to the extracellular domains of receptors is known to initiate signaling via activation of intracellular kinase domains. While the structure of insulin has been known since 1969, recent decades have seen remarkable progress on the structural biology of apo and liganded receptor fragments. Here, we review how this useful structural information (on ligands and receptors) has enabled large-scale atomically-resolved simulations to elucidate the conformational dynamics of these biomolecules. Particularly, applications of molecular dynamics (MD) and Monte Carlo (MC) simulation methods are discussed in various contexts, including studies of isolated ligands, apo-receptors, ligand/receptor complexes and intracellular kinase domains. The review concludes with a brief overview and future outlook for modeling and computational studies in this family of proteins.

Discovery of 2,4-bis-arylamino-1,3-pyrimidines as insulin-like growth factor-1 receptor (IGF-1R) inhibitors

The insulin-like growth factor-1 receptor (IGF-1R) plays an important role in the regulation of cell growth and differentiation, and in protection from apoptosis. IGF-1R has been shown to be an appealing target for the treatment of human cancer. Herein, we report the synthesis, structure-activity relationships (SAR), X-ray cocrystal structure and in vivo tumor study results for a series of 2,4-bis-arylamino-1,3-pyrimidines.

Insulin-like growth factor-1 receptor and ErbB kinase inhibitor combinations block proliferation and induce apoptosis through cyclin D1 reduction and Bax activation

The insulin-like growth factor-1 receptor (IGF-1R) and ErbB family of receptors are receptor tyrosine kinases that play important roles in cancer. Lack of response and resistance to therapies targeting ErbB receptors occur and are often associated with activation of the IGF-1R pathway. Combinations of agents that inhibit IGF-1R and ErbB receptors have been shown to synergistically block cancer cell proliferation and xenograft tumor growth. To determine the mechanism by which targeting both IGF-1R and ErbB receptors causes synergistic effects on cell growth and survival, we investigated the effects of combinations of selective IGF-1R and ErbB kinase inhibitors on proliferative and apoptotic signaling. We identified A431 squamous cell carcinoma cells as most sensitive to combinations of ErbB and IGF-1R inhibitors. The inhibitor combinations resulted in not only blockade of A431 cell proliferation, but also induced apoptosis, which was not seen with either agent alone. Upon examining phosphorylation states and expression levels of proteins in the IGF-1R and ErbB signaling pathways, we found a correlation between the ability of combinations to inhibit proliferation and to decrease levels of phosphorylated Akt and cyclin D1. In addition, the massive cell death induced by combined IGF-1R/ErbB inhibition was associated with Mcl-1 reduction and Bax activation. Thus, targeting both IGF-1R and ErbB receptors simultaneously results in cell cycle arrest and apoptosis through combined effects on Akt, cyclin D1, and Bax activation.

Selective inhibition of SCLC growth by the A12 anti-IGF-1R monoclonal antibody correlates with inhibition of Akt

Activation of the insulin-like growth factor-1 receptor (IGF-1R) by IGF-1 and IGF-2 plays a prominent role in the growth and survival of small cell lung cancer (SCLC) by potently activating the PI3K-Akt signal transduction pathway, which is also an important factor in the resistance of SCLC to chemotherapy. A12 is a fully human monoclonal antibody directed against the human IGF-1R that does not cross-react with the insulin receptor. In this study we have utilized A12 to determine the effects of selective antibody-mediated blockade of the IGF-1R on SCLC cell lines. Incubation with A12 resulted in a dose-dependent inhibition of IGF-1-stimulated IGF-1R and Akt activity, with maximal inhibition of approximately 75% at a concentration of 10mug/ml in the H526 cell line. Growth of the H526 and H146 cell lines in serum was inhibited by a maximum of 50-70% in a dose-dependent fashion, which correlated well with the extent of Akt inhibition. However, growth of the H69 and WBA cell lines was unaffected by A12. Despite almost complete inhibition of IGF-1R phosphorylation by A12, Akt activity remained constitutively high in these cell lines. H526 transfectants expressing a constitutively active Akt allele also were resistant to A12. Treatment with A12 additively enhanced response to carboplatin in the H526 and H146 cell lines but had no effect on the H69 and WBA cell lines. Treatment of the H526 cell line with a combination of A12 and rapamycin was highly synergistic. These data suggest that growth inhibition and chemosensitization of SCLC by A12 is directly correlated with the ability to inhibit PI3K-Akt signaling, with those cell lines showing constitutive PI3K-Akt signaling displaying a high level of resistance to IGF-1R targeted therapy.

Pyrazolo[3,4-d]pyrimidines as potent inhibitors of the insulin-like growth factor receptor (IGF-IR)

A high throughput screen of Abbott's compound repository revealed that the pyrazolo[3,4-d]pyrimidine class of kinase inhibitors possessed moderate potency for IGF-IR, a promising target for cancer chemotherapy. The synthesis and subsequent optimization of this class of compounds led to the discovery of 14, a compound that possesses in vivo IGF-IR inhibitory activity.