Robert Sullivan

Solution-phase parallel synthesis using ion-exchange resins

Abstract Ion-exchange resins are useful as scavengers in solution-phase parallel synthesis. Ester and amide libraries have been generated using basic ion-exchange resins to facilitate the formation of products and to remove reaction byproducts. Acidic ion-exchange resins have been used as selective amine scavengers in the synthesis of urea and amine libraries. Several compound libraries have been prepared using the basic ion-exchange resin Amberlyst 21 as part of our lead optimization program. The utility of ion-exchange resins as a means of generating both large and small focused libraries will be reviewed. Acidic and basic ion-exchange resins are useful reagents in solution-phase parallel synthesis. Ester and amide libraries have been generated using basic ion-exchange resins, and acidic ion-exchange resins have been used as selective amine scavengers in the synthesis of urea and amine libraries. The utility of ion-exchange resins as a means of generating focused libraries will be discussed.

2,5-Diaminopyrimidines and 3,5-disubstituted azapurines as inhibitors of glycogen synthase kinase-3 (GSK-3).

The discovery of two classes of pyrimidine-based inhibitors of GSK-3 is described. Optimization of these series led to inhibitors with IC(50)<10nM and >100-fold selectivity over Aurora A kinase. A proposed binding mode of 21b is presented. One compound (33) of the pyrimidine series showed promising pharmacokinetic parameters.

The design and synthesis of novel α-ketoamide-based p38 MAP kinase inhibitors

We have identified a novel series of potent p38 MAP kinase inhibitors through structure-based design which due to their extended molecular architecture bind, in addition to the ATP site, to an allosteric pocket. In vitro ADME and in vivo PK studies show these compounds to have drug-like characteristics which could result in the development of an oral treatment for inflammatory conditions.

KR-003048, a potent, orally active inhibitor of p38 mitogen-activated protein kinase

The tumor necrosis factor-alpha (TNF-alpha) cytokine, secreted by activated monocytes/macrophages and T lymphocytes, is implicated in several diseases, including rheumatoid arthritis, chronic obstructive pulmonary disease, inflammatory bowel disease, and osteoporosis. Monocyte/macrophage production of TNF-alpha is largely driven by p38alpha mitogen-activated protein kinase (MAP kinase), an intracellular soluble serine-threonine kinase. p38alpha MAP kinase is activated by growth factors, cellular stresses, and cytokines such as TNF-alpha and interleukin-l (IL-I). The primary contribution of p38alpha activation to excess TNF-alpha in settings of both chronic and acute inflammation has instigated efforts to find inhibitors of this enzyme as possible therapies for associated disease states. Analogue design, synthesis, and structure-activity studies led to the identification of 5-tert-butyl-N-cyclopropyl-2-methoxy-3-{2-[4-(2-morpholin-4-yl-ethoxy)-naphthalen-1-yl]-2-oxo-acetylamino}-benzamide (KR-003048) as a potent inhibitor of the p38 MAP kinase signaling pathway in vitro and in vivo. The inhibition in vitro of human p38alpha enzyme activity and lipopolysaccharide (LPS)-induced p38 activation and subsequent TNF-alpha release is described. KR-00348 was demonstrated to be a potent inhibitor of inflammatory cytokine production ex vivo in rat and human whole blood, and showed good oral bioavailability. Additionally, efficacy in mouse and rat models of acute and chronic inflammation was obtained. KR-003048 possessed therapeutic activity in acute models, demonstrating substantial inhibition of carrageenan-induced paw edema and in vivo LPS-induced TNF release at 30mg/kg p.o. Collagen-induced arthritis in mice was significantly inhibited by 10 and 30mg/kg doses of KR-003048. Evidence for disease-modifying activity in this model was indicated by histological evaluation of joints.

Optimization of α-ketoamide based p38 inhibitors through modifications to the region that binds to the allosteric site

We have optimized a novel series of potent p38 MAP kinase inhibitors based on an alpha-ketoamide scaffold through structure based design that due to their extended molecular architecture bind, in addition to the ATP site, to an allosteric pocket. In vitro ADME, in vivo PK and efficacy studies show these compounds to have drug-like characteristics and have resulted in the nomination of a development candidate which is currently in phase II clinical trials for the oral treatment of inflammatory conditions.

'Reverse' α-ketoamide-based p38 MAP kinase inhibitors

We have identified a second series of potent p38 inhibitors. As with our first generation series, these compounds are based on an alpha-ketoamide scaffold. The reversal of the ketoamide order, however, introduces more chemical flexibility and in addition results in improve potencies against p38.

PEPTIDE INHIBITORS OF IKB PROTEASE : MODIFICATION OF THE C-TERMINI OF Z-LLF-CHO

Abstract A series of tripeptides (Z-LLF-R) with various modifications at their C-terminus were synthesized and evaluated for their ability to prevent the activation of NF-κB through inhibition of IκB protease. Of the compounds evaluated only the C-terminal aldehydes 5a,b were active in our Jurkat T-cell based assay. Compound 5a also decreased IL-2 and IL-8 levels in these cells indicating that inhibitors of IκB protease can have an effect on various signaling pathways.

Small Molecules Co-targeting CKIα and the Transcriptional Kinases CDK7/9 Control AML in Preclinical Models.

CKIα ablation induces p53 activation, and CKIα degradation underlies the therapeutic effect of lenalidomide in a pre-leukemia syndrome. Here we describe the development of CKIα inhibitors, which co-target the transcriptional kinases CDK7 and CDK9, thereby augmenting CKIα-induced p53 activation and its anti-leukemic activity. Oncogene-driving super-enhancers (SEs) are highly sensitive to CDK7/9 inhibition. We identified multiple newly gained SEs in primary mouse acute myeloid leukemia (AML) cells and demonstrate that the inhibitors abolish many SEs and preferentially suppress the transcription elongation of SE-driven oncogenes. We show that blocking CKIα together with CDK7 and/or CDK9 synergistically stabilize p53, deprive leukemia cells of survival and proliferation-maintaining SE-driven oncogenes, and induce apoptosis. Leukemia progenitors are selectively eliminated by the inhibitors, explaining their therapeutic efficacy with preserved hematopoiesis and leukemia cure potential; they eradicate leukemia in MLL-AF9 and Tet2-/-;Flt3ITD AML mouse models and in several patient-derived AML xenograft models, supporting their potential efficacy in curing human leukemia.