An evaluation of in-house and off-the-shelf in silico models: implications on guidance for mutagenicity assessment.

The evaluation of impurities for genotoxicity using in silico models are commonplace and have become accepted by regulatory agencies. Recently, the ICH M7 Step 4 guidance was published and requires two complementary models for genotoxicity assessments. Over the last ten years, many companies have developed their own internal genotoxicity models built using both public and in-house chemical structures and bacterial mutagenicity data. However, the proprietary nature of internal structures prevents sharing of data and the full OECD compliance of such models. This analysis investigated whether using in-house internal compounds for training models is needed and substantially impacts the results of in silico genotoxicity assessments, or whether using commercial-off-the-shelf (COTS) packages such as Derek Nexus or Leadscope provide adequate performance. We demonstrated that supplementation of COTS packages with a Support Vector Machine (SVM) QSAR model trained on combined in-house and public data does, in fact, improve coverage and accuracy, and reduces the number of compounds needing experimental assessment, i.e., the liability load. This result indicates that there is added value in models trained on both internal and public structures and incorporating such models as part of a consensus approach improves the overall evaluation. Lastly, we optimized an in silico consensus decision-making approach utilizing two COTS models and an internal (SVM) model to minimize false negatives.

Metabolic alterations in cancer cells and therapeutic implications.

Cancer metabolism has emerged as an important area of research in recent years. Elucidation of the metabolic differences between cancer and normal cells and the underlying mechanisms will not only advance our understanding of fundamental cancer cell biology but also provide an important basis for the development of new therapeutic strategies and novel compounds to selectively eliminate cancer cells by targeting their unique metabolism. This article reviews several important metabolic alterations in cancer cells, with an emphasis on increased aerobic glycolysis (the Warburg effect) and glutamine addiction, and discusses the mechanisms that may contribute to such metabolic changes. In addition, metabolic alterations in cancer stem cells, mitochondrial metabolism and its influence on drug sensitivity, and potential therapeutic strategies and agents that target cancer metabolism are also discussed.

In vitro and in vivo characterization of SGI-1252, a small molecule inhibitor of JAK2.

OBJECTIVE: Constitutive activation of the Janus kinase 2 (JAK2) due to a somatic mutation (JAK2(V617F)) arising in hematopoietic stem cells plays a central role in the pathophysiology of myeloproliferative neoplasms (MPNs). To investigate the hypothesis that drugs that inhibit JAK2 have therapeutic potential, we developed a small molecule inhibitor, SGI-1252, that targets the adenosine triphosphate-binding and solvent pocket of the protein. MATERIALS AND METHODS: Established cells lines each expressing different JAK2(V617F) copy numbers, a cell line transfected with wild-type and mutant JAK2, ex vivo expanded erythroid progenitor cells from patients with MPNs, and a murine xenograft model were used to characterize the activity of SGI-1252. RESULTS: In vitro studies showed that SGI-1252 potently inhibits the kinase activity of wild-type JAK2, JAK2(V617F) and JAK1, but not JAK3. SGI-1252 blocked phosphorylation of signal transducers and activators of transcription 5, a downstream target of JAK2 and inhibited expression of the JAK2-dependent antiapoptotic gene BCL-X(L). Additional studies confirmed induction of apoptosis in JAK2(V617F)-positive cell lines by SGI-1252. Moreover, cell lines transfected with either wild-type JAK2 or JAK2(V617F) were equally susceptible to the antiproliferative effects of SGI-1252 and the antiproliferative activity of SGI-1252 toward ex vivo--expanded erythroid progenitors from patients with polycythemia vera and primary myelofibrosis appeared independent of the JAK2(V617F) allele burden. Pharmacodynamic studies in a murine xenograft model demonstrated both anti-tumor activity and inhibition of signal transducers and activators of transcription 5 phosphorylation by SGI-1252, and the drug was active and well-tolerated whether delivered intraperitoneally or orally. CONCLUSIONS: Together, these studies support further development of SGI-1252 for clinical use.

Synthesis of biotinylated OSW-1.

OSW-1 is a highly potent anticancer natural saponin with an unknown mode of action. To determine its cellular target(s) biotinylated OSW-1 was successfully synthesized in nine steps.