Acquired On-Target Clinical Resistance Validates FGFR4 as a Driver of Hepatocellular Carcinoma.

Hepatocellular carcinoma (HCC) is a leading cause of cancer mortality worldwide with no clinically confirmed oncogenic driver. Although preclinical studies implicate the FGF19 receptor FGFR4 in hepatocarcinogenesis, the dependence of human cancer on FGFR4 has not been demonstrated. Fisogatinib (BLU-554) is a potent and selective inhibitor of FGFR4 and demonstrates clinical benefit and tumor regression in patients with HCC with aberrant FGF19 expression.

Precision Targeted Therapy with BLU-667 for -Driven Cancers.

The receptor tyrosine kinase rearranged during transfection (RET) is an oncogenic driver activated in multiple cancers, including non-small cell lung cancer (NSCLC), medullary thyroid cancer (MTC), and papillary thyroid cancer. No approved therapies have been designed to target RET; treatment has been limited to multikinase inhibitors (MKI), which can have significant off-target toxicities and limited efficacy. BLU-667 is a highly potent and selective RET inhibitor designed to overcome these limitations.

Discovery of a potent and isoform-selective targeted covalent inhibitor of the lipid kinase PI3Kα.

PI3Kα has been identified as an oncogene in human tumors. By use of rational drug design, a targeted covalent inhibitor 3 (CNX-1351) was created that potently and specifically inhibits PI3Kα. We demonstrate, using mass spectrometry and X-ray crystallography, that the selective inhibitor covalently modifies PI3Kα on cysteine 862 (C862), an amino acid unique to the α isoform, and that PI3Kβ, -γ, and -δ are not covalently modified.

Selective irreversible inhibition of a protease by targeting a noncatalytic cysteine.

Designing selective inhibitors of proteases has proven problematic, in part because pharmacophores that confer potency exploit the conserved catalytic apparatus. We developed a fundamentally different approach by designing irreversible inhibitors that target noncatalytic cysteines that are structurally unique to a target in a protein family. We have successfully applied this approach to the important therapeutic target HCV protease, which has broad implications for the design of other selective protease inhibitors.

TH1 and TH2 cytokine inhibition by 3,5-bis(trifluoromethyl)pyrazoles, a novel class of immunomodulators.

In order to discover novel immunomodulators for application in treating autoimmune diseases, a stable Jurkat transfectant was constructed in which luciferase reporter gene is driven by a full-length IL-2 promotor. A chemical library was screened to identify compounds that inhibited luciferase expression in Jurkat transfectants stimulated with PMA and ionomycin. A class of compounds (bis-trifluoromethyl pyrazole, BTPs) was identified from this screen.

Potent inhibition of NFAT activation and T cell cytokine production by novel low molecular weight pyrazole compounds.

NFAT (nuclear factor of activated T cell) proteins are expressed in most immune system cells and regulate the transcription of cytokine genes critical for the immune response. The activity of NFAT proteins is tightly regulated by the Ca(2+)/calmodulin-dependent protein phosphatase 2B/calcineurin (CaN). Dephosphorylation of NFAT by CaN is required for NFAT nuclear localization.

3,5-Bis(trifluoromethyl)pyrazoles: a novel class of NFAT transcription factor regulator.

A series of bis(trifluoromethyl)pyrazoles (BTPs) has been found to be a novel inhibitor of cytokine production. Identified initially as inhibitors of IL-2 synthesis, the BTPs have been optimized in this regard and even inhibit IL-2 production with a 10-fold enhancement over cyclosporine in an ex vivo assay. Additionally, the BTPs show inhibition of IL-4, IL-5, IL-8, and eotaxin production.

Development of a p38 Kinase Binding Assay for High Throughput Screening.

p38 is a member of the mitogen-activated protein kinase (MAPK) family of serine/threonine kinases, which is activated by cellular stressors and has been shown to be a critical enzyme in the synthesis and action of proinflammatory cytokines, tumor necrosis factor-a (TNF-alpha) and interleukin-1beta (IL-1beta). A group of pyridinyl imidazole compounds such as SB202190 have been identified as selective inhibitors of p38 that bind directly to the ATP pocket of the enzyme. These compounds inhibit the p38 kinase activity, block TNF-alpha and IL-1beta secretion both in vivo and in vitro and are found to be effective in animal models of arthritis, bone resorption, and endotoxin shock.

A macrolactam inhibitor of T helper type 1 and T helper type 2 cytokine biosynthesis for topical treatment of inflammatory skin diseases.

T lymphocytes play a critical part in inflammatory skin diseases but are targeted by available therapies that have only partial efficacy, significant side-effects, or both. Because psoriasis, atopic dermatitis, and allergic contact hypersensitivity are associated with T helper type 1 (Th1), T helper type 2 (Th2), or mixed Th1-Th2 cell subsets and cytokine types, respectively, there is a need for a better broad-based inhibitor. The macrolactam ascomycin analog, ABT-281, was found to inhibit potently T cell function across species and to inhibit expression of multiple cytokines in human peripheral blood leukocytes which have been found in human skin disease cells and tissues.

Discovery of ascomycin analogs with potent topical but weak systemic activity for treatment of inflammatory skin diseases.

Drug therapy for the major inflammatory skin diseases, which include atopic dermatitis, psoriasis and allergic contact dermatitis, is often inadequate due to poor efficacy, toxicity, or both. Much research has focused on the macrolactam T cell inhibitors as a promising new class of agents for immunotherapy, and medicinal chemistry efforts to design novel ascomycin analogs have produced clinically promising agents. A synthetic program to modify the ascomycin nucleus to alter its physicochemical properties and promote systemic clearance is described.

Inhibition of p56(lck) tyrosine kinase by isothiazolones.

Lck encodes a 56-kDa protein-tyrosine kinase, predominantly expressed in T lymphocytes, crucial for initiating T cell antigen receptor (TCR) signal transduction pathways, culminating in T cell cytokine gene expression and effector functions. As a consequence of a high-throughput screen for selective, novel inhibitors of p56(lck), an isothiazolone compound was identified, methyl-3-(N-isothiazolone)-2-thiophenecarboxylate(A-125800), which inhibits p56(lck) kinase activity with IC50 = 1-7 microM. Under similar assay conditions, the isothiazolone compound was equipotent in blocking the ZAP-70 tyrosine kinase activity but was 50 to 100 times less potent against the catalytic activities of p38 MAP kinase and c-Jun N-terminal kinase 2alpha.

Ex vivo assessment of immunosuppression in undiluted whole blood from pigs dosed with tacrolimus (FK506).

To assess the duration of immunosuppression in FK506-dosed pigs, an undiluted whole blood assay was established to measure reactivities of T cells in their physiological milieu. PMA and ionomycin were shown to induce IL-2 production in swine blood. The IC50 of FK506 in inhibiting IL-2 production in whole blood and isolated PBMC stimulated with PMA and ionomycin measured 1.

Synthesis and immunosuppressant activity of pyrazole carboxamides.

A series of novel pyrazole carboxamides is disclosed that demonstrate strong immunosuppressant activity in rodent and human mixed leukocyte response (MLR) assays (IC50 < 1 microM). The synthesis, biological activity, mode of action, and pharmacokinetic properties of this new lead series are discussed.