Wnt signaling is one of the key oncogenic pathways in multiple cancers, and targeting this pathway is an attractive therapeutic approach. However, therapeutic success has been limited because of the lack of therapeutic agents for targets in the Wnt pathway and the lack of a defined patient population that would be sensitive to a Wnt inhibitor. We developed a screen for small molecules that block Wnt secretion. This effort led to the discovery of LGK974, a potent and specific small-molecule Porcupine (PORCN) inhibitor. PORCN is a membrane-bound O-acyltransferase that is required for and dedicated to palmitoylation of Wnt ligands, a necessary step in the processing of Wnt ligand secretion. We show that LGK974 potently inhibits Wnt signaling in vitro and in vivo, including reduction of the Wnt-dependent LRP6 phosphorylation and the expression of Wnt target genes, such as AXIN2.LGK974 is potent and efficacious in multiple tumor models at well-tolerated doses in vivo, including murine and rat mechanistic breast cancer models driven by MMTV-Wnt1 and a human head and neck squamous cell carcinoma model (HN30). We also show that head and neck cancer cell lines with loss-of-function mutations in the Notch signaling pathway have a high response rate to LGK974. Together, these findings provide both a strategy and tools for targeting Wntdriven cancers through the inhibition of PORCN.Wnt inhibition | β-catenin | HNSCC

SUMMARY In an effort to find new pharmacological modalities to overcome resistance to ATP-site inhibitors of Bcr-Abl, we recently reported the discovery of GNF-2, a selective allosteric Bcr-Abl inhibitor. Here, using solution NMR, X-ray crystallography, mutagenesis and hydrogen exchange mass spectrometry we demonstrate that GNF-2 binds to the myristate binding site of Abl, leading to changes in the structural dynamics of the ATP-binding site. GNF-5, an analog of GNF-2 having improved pharmacokinetic properties, when utilized in combination with the ATP-competitive inhibitors imatinib or nilotinib, suppressed the emergence of resistance mutations in vitro, displayed additive inhibitory activity in biochemical and cellular assays against T315I Bcr-Abl and displayed in vivo efficacy against the recalcitrant T315I Bcr-Abl mutant in a murine bone-marrow transplantation model. These results demonstrate that therapeutically relevant inhibition of Bcr-Abl activity can be achieved using inhibitors that bind to the myristate binding site and that combining allosteric and ATP-competitive inhibitors can overcome resistance to either agent alone.

The synthesis, preclinical profile, and in vivo efficacy in rat xenograft models of the novel and selective anaplastic lymphoma kinase inhibitor 15b (LDK378) are described. In this initial report, preliminary structure-activity relationships (SARs) are described as well as the rational design strategy employed to overcome the development deficiencies of the first generation ALK inhibitor 4 (TAE684). Compound 15b is currently in phase 1 and phase 2 clinical trials with substantial antitumor activity being observed in ALK-positive cancer patients.

TGF-␤ has been shown to play a critical role in anti-inflammation; however, the signaling mechanisms of TGF-␤ in anti-inflammatory response remains largely unclear. This study reported that mice that overexpress latent TGF-␤1 on skin are protected against renal inflammation in a model of obstructive kidney disease and investigated the signaling mechanism of TGF-␤1 in inhibition of renal inflammation in vivo and in vitro. Seven days after urinary obstruction, wild-type mice developed severe renal inflammation, including massive T cell and macrophage infiltration and marked upregulation of IL-1␤, TNF-␣, and intercellular adhesion molecule-1 (all P < 0.001). Surprising, renal inflammation was prevented in transgenic mice. This was associated with an increase in latent TGF-␤1 in circulation (a 10-fold increase) and renal tissues (a 2.5-fold increase). Further studies showed that inhibition of renal inflammation in TGF-␤1 transgenic mice was also associated with a marked upregulation of renal Smad7 and IB␣ and a suppression of NF-B activation in the diseased kidney (all P < 0.01). These in vivo findings suggested the importance of TGF-␤-NF-B cross-talk signaling pathway in regulating renal inflammation. This was tested in vitro in a doxycycline-regulated Smad7-expressing renal tubular cell line. Overexpression of Smad7 was able to upregulate IB␣ directly in a time-and dose-dependent manner, thereby inhibiting NF-B activation and NF-B-driven inflammatory response. In conclusion, latent TGF-␤ may have protective roles in renal inflammation. Smad7-mediated inhibition of NF-B activation via the induction of IkB␣ may be the central mechanism by which latent TGF-␤ prevents renal inflammation.

The prognosis of head-and-neck squamous cell carcinoma (HNSCC) has not been improved in the past 20 years. Validation of HNSCC biomarkers for targeted therapy has been hindered by a lack of animal models mimicking human HNSCC at both the pathological and molecular levels. Here we report that overexpression of K-ras or H-ras and loss of transforming growth factor-␤ type II receptor (TGF␤RII) are common events in human HNSCC. Activation of either K-ras or H-ras in combination with TGF␤RII deletion from mouse head-and-neck epithelia caused HNSCC with complete penetrance, some of which progressed to metastases. These tumors displayed pathology indistinguishable from human HNSCCs and exhibited multiple molecular alterations commonly found in human HNSCCs. Additionally, elevated endogenous TGF␤1 in these lesions contributed to inflammation and angiogenesis. Our data suggest that targeting common oncogenic pathways in tumor epithelia together with blocking the effect of TGF␤1 on tumor stroma may provide a novel therapeutic strategy for HNSCC.[Keywords: HNSCC; head-and-neck-specific knockout; metastasis; Ras; TGF␤RII; TGF␤1] Supplemental material is available at http://www.genesdev.org.