Barbara Mroczkowski

An Orally Available Small-Molecule Inhibitor of c-Met, PF-2341066, Exhibits Cytoreductive Antitumor Efficacy through Antiproliferative and Antiangiogenic Mechanisms

The c-Met receptor tyrosine kinase and its ligand, hepatocyte growth factor (HGF), have been implicated in the progression of several human cancers and are attractive therapeutic targets. PF-2341066 was identified as a potent, orally bioavailable, ATP-competitive small-molecule inhibitor of the catalytic activity of c-Met kinase. PF-2341066 was selective for c-Met (and anaplastic lymphoma kinase) compared with a panel of >120 diverse tyrosine and serine-threonine kinases. PF-2341066 potently inhibited c-Met phosphorylation and c-Met-dependent proliferation, migration, or invasion of human tumor cells in vitro (IC(50) values, 5-20 nmol/L). In addition, PF-2341066 potently inhibited HGF-stimulated endothelial cell survival or invasion and serum-stimulated tubulogenesis in vitro, suggesting that this agent also exhibits antiangiogenic properties. PF-2341066 showed efficacy at well-tolerated doses, including marked cytoreductive antitumor activity, in several tumor models that expressed activated c-Met. The antitumor efficacy of PF-2341066 was dose dependent and showed a strong correlation to inhibition of c-Met phosphorylation in vivo. Near-maximal inhibition of c-Met activity for the full dosing interval was necessary to maximize the efficacy of PF-2341066. Additional mechanism-of-action studies showed dose-dependent inhibition of c-Met-dependent signal transduction, tumor cell proliferation (Ki67), induction of apoptosis (caspase-3), and reduction of microvessel density (CD31). These results indicated that the antitumor activity of PF-2341066 may be mediated by direct effects on tumor cell growth or survival as well as antiangiogenic mechanisms. Collectively, these results show the therapeutic potential of targeting c-Met with selective small-molecule inhibitors for the treatment of human cancers.

Cytoreductive antitumor activity of PF-2341066, a novel inhibitor of anaplastic lymphoma kinase and c-Met, in experimental models of anaplastic large-cell lymphoma

A t(2;5) chromosomal translocation resulting in expression of an oncogenic kinase fusion protein known as nucleophosmin-anaplastic lymphoma kinase (NPM-ALK) has been implicated in the pathogenesis of anaplastic large-cell lymphoma (ALCL). PF-2341066 was recently identified as a p.o. bioavailable, small-molecule inhibitor of the catalytic activity of c-Met kinase and the NPM-ALK fusion protein. PF-2341066 also potently inhibited NPM-ALK phosphorylation in Karpas299 or SU-DHL-1 ALCL cells (mean IC50 value, 24 nmol/L). In biochemical and cellular screens, PF-2341066 was shown to be selective for c-Met and ALK at pharmacologically relevant concentrations across a panel of >120 diverse kinases. PF-2341066 potently inhibited cell proliferation, which was associated with G1-S–phase cell cycle arrest and induction of apoptosis in ALK-positive ALCL cells (IC50 values, ∼30 nmol/L) but not ALK-negative lymphoma cells. The induction of apoptosis was confirmed using terminal deoxyribonucleotide transferase–mediated nick-end labeling and Annexin V staining (IC50 values, 25–50 nmol/L). P.o. administration of PF-2341066 to severe combined immunodeficient-Beige mice bearing Karpas299 ALCL tumor xenografts resulted in dose-dependent antitumor efficacy with complete regression of all tumors at the 100 mg/kg/d dose within 15 days of initial compound administration. A strong correlation was observed between antitumor response and inhibition of NPM-ALK phosphorylation and induction of apoptosis in tumor tissue. In addition, inhibition of key NPM-ALK signaling mediators, including phospholipase C-γ, signal transducers and activators of transcription 3, extracellular signal-regulated kinases, and Akt by PF-2341066 were observed at concentrations or dose levels, which correlated with inhibition of NPM-ALK phosphorylation and function. Collectively, these data illustrate the potential clinical utility of inhibitors of NPM-ALK in treatment of patients with ALK-positive ALCL. [Mol Cancer Ther 2007;6(12):3314–22]

Structure Based Drug Design of Crizotinib (Pf-02341066), a Potent and Selective Dual Inhibitor of Mesenchymal-Epithelial Transition Factor (C-met) Kinase and Anaplastic Lymphoma Kinase (Alk).

Because of the critical roles of aberrant signaling in cancer, both c-MET and ALK receptor tyrosine kinases are attractive oncology targets for therapeutic intervention. The cocrystal structure of 3 (PHA-665752), bound to c-MET kinase domain, revealed a novel ATP site environment, which served as the target to guide parallel, multiattribute drug design. A novel 2-amino-5-aryl-3-benzyloxypyridine series was created to more effectively make the key interactions achieved with 3. In the novel series, the 2-aminopyridine core allowed a 3-benzyloxy group to reach into the same pocket as the 2,6-dichlorophenyl group of 3 via a more direct vector and thus with a better ligand efficiency (LE). Further optimization of the lead series generated the clinical candidate crizotinib (PF-02341066), which demonstrated potent in vitro and in vivo c-MET kinase and ALK inhibition, effective tumor growth inhibition, and good pharmaceutical properties.

Structure-based design of novel human Pin1 inhibitors (I).

Pin1 is a member of the cis-trans peptidyl-prolyl isomerase family with potential anti-cancer therapeutic value. Here we report structure-based de novo design and optimization of novel Pin1 inhibitors. Without a viable lead from internal screenings, we designed a series of novel Pin1 inhibitors by interrogating and exploring a protein crystal structure of Pin1. The ligand efficiency of the initial concept molecule was optimized with integrated SBDD and parallel chemistry approaches, resulting in a more attractive lead series.