Debio 0617B Inhibits Growth of STAT3-Driven Solid Tumors through Combined Inhibition of JAK, SRC, and Class III/V Receptor Tyrosine Kinases.

Tumor survival, metastases, chemoresistance, and escape from immune responses have been associated with inappropriate activation of STAT3 and/or STAT5 in various cancers, including solid tumors. Debio 0617B has been developed as a first-in-class kinase inhibitor with a unique profile targeting phospho-STAT3 (pSTAT3) and/or pSTAT5 in tumors through combined inhibition of JAK, SRC, ABL, and class III/V receptor tyrosine kinases (RTK). Debio 0617B showed dose-dependent inhibition of pSTAT3 in STAT3-activated carcinoma cell lines; Debio 0617B also showed potent antiproliferative activity in a panel of cancer cell lines and in patient-derived tumor xenografts tested in an in vitro clonogenic assay. Debio 0617B showed in vivo efficacy by inhibiting tumor growth in several mouse xenograft models. To increase in vivo efficacy and STAT3 inhibition, Debio 0617B was tested in combination with the EGFR inhibitor erlotinib in a non-small cell lung cancer xenograft model. To evaluate the impact of in vivo STAT3 blockade on metastases, Debio 0617B was tested in an orthotopic tumor model. Measurement of primary tumor weight and metastatic counts in lung tissue demonstrated therapeutic efficacy of Debio 0617B in this model. These data show potent activity of Debio 0617B on a broad spectrum of STAT3-driven solid tumors and synergistic activity in combination with EGFR inhibition. Mol Cancer Ther; 15(10); 2334-43. ©2016 AACR.

New aromatase inhibitors from the 3-pyridyl arylether and 1-aryl pyrrolo[2,3-c]pyridine series.

Aromatase inhibition is the new standard of care for estrogen receptor positive breast cancer and has also potential for treatment of other diseases such as endometriosis. Simple and readily available 3-pyridyl arylethers and 1-aryl pyrrolo[2,3-c]pyridines recapitulating the key pharmacophore elements of Letrozole (1) are described and their structure-activity relationships are discussed. Potent and ligand efficient leads such as compound 23 (IC(50)=59nM on aromatase) have been identified.

Potent and selective inhibition of polycythemia by the quinoxaline JAK2 inhibitor NVP-BSK805.

The recent discovery of an acquired activating point mutation in JAK2, substituting valine at amino acid position 617 for phenylalanine, has greatly improved our understanding of the molecular mechanism underlying chronic myeloproliferative neoplasms. Strikingly, the JAK2(V617F) mutation is found in nearly all patients suffering from polycythemia vera and in roughly every second patient suffering from essential thrombocythemia and primary myelofibrosis. Thus, JAK2 represents a promising target for the treatment of myeloproliferative neoplasms and considerable efforts are ongoing to discover and develop inhibitors of the kinase. Here, we report potent inhibition of JAK2(V617F) and JAK2 wild-type enzymes by a novel substituted quinoxaline, NVP-BSK805, which acts in an ATP-competitive manner. Within the JAK family, NVP-BSK805 displays more than 20-fold selectivity towards JAK2 in vitro, as well as excellent selectivity in broader kinase profiling. The compound blunts constitutive STAT5 phosphorylation in JAK2(V617F)-bearing cells, with concomitant suppression of cell proliferation and induction of apoptosis. In vivo, NVP-BSK805 exhibited good oral bioavailability and a long half-life. The inhibitor was efficacious in suppressing leukemic cell spreading and splenomegaly in a Ba/F3 JAK2(V617F) cell-driven mouse mechanistic model. Furthermore, NVP-BSK805 potently suppressed recombinant human erythropoietin-induced polycythemia and extramedullary erythropoiesis in mice and rats.

2-Amino-aryl-7-aryl-benzoxazoles as potent, selective and orally available JAK2 inhibitors.

A series of novel benzoxazole derivatives has been designed and shown to exhibit attractive JAK2 inhibitory profiles in biochemical and cellular assays, capable of delivering compounds with favorable PK properties in rats. Synthesis and structure-activity relationship data are also provided.

Entry into a new class of protein kinase inhibitors by pseudo ring design.

A pyrimidin-4-yl-urea motif forming a pseudo ring by intramolecular hydrogen bonding has been designed to mimic the pyrido[2,3-d]pyrimidin-7-one core structure of a well-established class of protein kinase inhibitors. Potent inhibition of a number of protein kinases was obtained with the first prototype compound synthesized to probe the design concept.

Novel beta-lactam derivatives: potent and selective inhibitors of the chymotrypsin-like activity of the human 20S proteasome.

A series of beta-lactam derivatives has been designed and synthesized to inhibit the chymotrypsin-like activity of the human 20S proteasome. The most potent compounds of this new structural class of beta-subunit selective 20S proteasome inhibitors exhibit IC50 values in the low-nanomolar range and show good selectivity over the trypsin-like and post-glutamyl-peptide hydrolytic activities of the enzyme.

Entry into a new class of potent proteasome inhibitors having high antiproliferative activity by structure-based design.

Proteasome inhibition is a therapeutic concept of current interest in anticancer research. We report here the design, synthesis, and biological characterization of prototypes of a new class of noncovalent proteasome inhibitors showing high activity in biochemical and cellular assays.

Structure-based optimisation of 2-aminobenzylstatine derivatives: potent and selective inhibitors of the chymotrypsin-like activity of the human 20S proteasome.

We have identified 2-aminobenzylstatine derivatives that inhibit non-covalently the chymotrypsin-like activity of the human 20S proteasome. A structure-based optimisation approach has allowed us to improve the potency of this structural class of proteasome inhibitors from micromolar to nanomolar level. The new derivatives showed good selectivity against the trypsin-like and post-glutamyl-peptide hydrolytic activities of this enzyme.