Targeted mutagenesis in mice demonstrates that the POU-domain gene Brn4/Pou3f4 plays a crucial role in the patterning of the mesenchymal compartment of the inner ear. Brn4 is expressed extensively throughout the condensing mesenchyme of the developing inner ear. Mutant animals displayed behavioral anomalies that resulted from functional deficits in both the auditory and vestibular systems, including vertical head bobbing, changes in gait, and hearing loss. Anatomical analyses of the temporal bone, which is derived in part from the otic mesenchyme, demonstrated several dysplastic features in the mutant animals, including enlargement of the internal auditory meatus. Many phenotypic features of the mutant animals resulted from the reduction or thinning of the bony compartment of the inner ear. Histological analyses demonstrated a hypoplasia of those regions of the cochlea derived from otic mesenchyme, including the spiral limbus, the scala tympani, and strial fibrocytes. Interestingly, we observed a reduction in the coiling of the cochlea, which suggests that Brn-4 plays a role in the epithelial-mesenchymal communication necessary for the cochlear anlage to develop correctly. Finally, the stapes demonstrated several malformations, including changes in the size and morphology of its footplate. Because the stapes anlage does not express the Brn4 gene, stapes malformations suggest that the Brn4 gene also plays a role in mesenchymal-mesenchymal signaling. On the basis of these data, we suggest that Brn-4 enhances the survival of mesodermal cells during the mesenchymal remodeling that forms the mature bony labyrinth and regulates inductive signaling mechanisms in the otic mesenchyme.

The roles of aberrant expression of constitutively active ALK chimeric proteins in the pathogenesis of anaplastic large-cell lymphoma (ALCL) have been well defined; nevertheless, the notion that ALK is a molecular target for the therapeutic modulation of ALK ؉ ALCL has not been validated thus far. Select fused pyrrolocarbazole (FP)-derived small molecules with ALK inhibitory activity were used as pharmacologic tools to evaluate whether functional ALK is essential for the prolifera- IntroductionChromosomal translocations occur frequently in a select group of human cancers, including most lymphomas, leukemias, and sarcomas. Individual translocations have shown a high degree of specificity for particular cancer types and the presence of a particular translocation often correlates well with clinical behavior and outcome for specific types of cancer. 1 Consequently, therapies directed at molecular targets dysregulated by tumor-specific genetic aberrations will potentially provide more effective and less toxic therapies than conventional chemotherapy. 1,2 Anaplastic large-cell lymphomas (ALCLs) comprise a group of non-Hodgkin lymphomas (NHLs) that are usually of T-cell origin and often present with extranodal disease, especially the skin, and are characterized by the expression of the CD30/Ki-1 antigen. Roughly 2500 to 3000 new cases of ALCLs are diagnosed in the United States each year and 50% to 60% of these ALCLs are associated with a specific t(2;5) (p23;q35) chromosome translocation. 4,5 The genes altered in the t(2;5) translocation contain the N-terminal portion of nucleophosmin (NPM) gene, a nuclear phosphoprotein, fused to the catalytic domain of anaplastic lymphoma kinase (ALK) gene. ALK is a cell-membrane-spanning receptor tyrosine kinase and a member of the insulin receptor superfamily. Although the precise physiologic function and regulation of ALK have not been well defined, the NPM-ALK fusion gene encodes for an 80-kDa NPM-ALK chimeric oncoprotein with constitutively active ALK tyrosine kinase activity, which plays a key role in lymphomagenesis by the aberrant phosphorylation of multiple intracellular substrates downstream of NPM-ALK. 4,5 Subsequently, other fusion partners of ALK were also reported in ALCL, and dysregulated expression and constitutive activation of the ALK protein was demonstrated in approximately 60% to 70% of ALCLs, termed ALK ϩ lymphomas. 4,[6][7][8] Preclinical experimental data have demonstrated that the aberrant expression of constitutively active ALK is directly implicated in the pathogenesis of ALCL and that ALK down-regulation or inhibition of ALK-mediated pathways can markedly impair the growth of ALK ϩ lymphoma cells. 9-15 Currently there is no optimal therapeutic regimen for ALK ϩ ALCL. Doxorubicin-based combination chemotherapy has limited effectiveness, resulting in a substantial number of patients with ALK ϩ ALCL with a poor outcome, either failing to enter remission or relapsing within a few months from the start of treatment. 3 Thus, optimal and more effective therapeu...

No abstract

Analogues structurally related to anaplastic lymphoma kinase (ALK) inhibitor 1 were optimized for metabolic stability. The results from this endeavor not only led to improved metabolic stability, pharmacokinetic parameters, and in vitro activity against clinically derived resistance mutations but also led to the incorporation of activity for focal adhesion kinase (FAK). FAK activation, via amplification and/or overexpression, is characteristic of multiple invasive solid tumors and metastasis. The discovery of the clinical stage, dual FAK/ALK inhibitor 27b, including details surrounding SAR, in vitro/in vivo pharmacology, and pharmacokinetics, is reported herein.

A series of novel 7-amino-1, 3,4,5-tetrahydrobenzo[b]azepin-2-one derivatives within the diaminopyrimidine class of kinase inhibitors were identified that target anaplastic lymphoma kinase (ALK). These inhibitors are potent against ALK in an isolated enzyme assay and inhibit autophosphorylation of the oncogenic fusion protein NPM-ALK in anaplastic large cell lymphoma (ALCL) cell lines. The lead inhibitor 15, which incorporates a bicyclo[2.2.1]hept-5-ene ring system in place of an aryl moiety, activates the pro-apoptotic caspases (3 and 7) and displays selective cytotoxicity against ALK-positive ALCL cells. Furthermore, 15 provides more than 40-fold selectivity against the structurally related insulin receptor, is orally bioavailable in multiple species, and displays in vivo antitumor efficacy when dosed orally in ALK-positive ALCL tumor xenografts in Scid mice.