The high frequency of activating RAS or BRAF mutations in cancer provides strong rationale for targeting the mitogen-activated protein kinase (MAPK) pathway. Selective BRAF and MAP-ERK kinase (MEK) inhibitors have shown clinical effi cacy in patients with melanoma. However, the majority of responses are transient, and resistance is often associated with pathway reactivation of the extracellular signal-regulated kinase (ERK) signaling pathway. Here, we describe the identifi cation and characterization of SCH772984, a novel and selective inhibitor of ERK1/2 that displays behaviors of both type I and type II kinase inhibitors. SCH772984 has nanomolar cellular potency in tumor cells with mutations in BRAF , NRAS , or KRAS and induces tumor regressions in xenograft models at tolerated doses. Importantly, SCH772984 effectively inhibited MAPK signaling and cell proliferation in BRAF or MEK inhibitor-resistant models as well as in tumor cells resistant to concurrent treatment with BRAF and MEK inhibitors. These data support the clinical development of ERK inhibitors for tumors refractory to MAPK inhibitors. SIGNIFICANCE: BRAF and MEK inhibitors have activity in MAPK-dependent cancers with BRAF or RAS mutations. However, resistance is associated with pathway alterations resulting in phospho-ERK reactivation. Here, we describe a novel ERK1/2 kinase inhibitor that has antitumor activity in MAPK inhibitor-naïve and MAPK inhibitor-resistant cells containing BRAF or RAS mutations. Cancer Discov; 3(7); 742-50.

The present study strongly suggests that an antibody to TGF-beta is a promising agent to prevent renal tubular fibrosis and apoptosis in UUO.

Objective. Diffuse systemic sclerosis (SSc; scleroderma) is a debilitating disease characterized by excessive dermal fibrosis with later progression to internal organs. In addition to the fibrotic component, major aspects of the disease include vascular or circulatory involvement and immune dysregulation evidenced by inflammatory cells in affected tissues and production of autoantibodies. Many animal models resembling this disease have been studied, including genetic models in mice and chickens, challenge with chemicals such as bleomycin or vinyl chloride to induce fibrosis, and models of graft-versus-host (GVH)-induced disease using certain strains of mice with differences in minor histocompatibility loci. The present studies were undertaken to determine if alteration of the induction of GVH-induced scleroderma could result in a model that more fully represented the human condition. Methods. Disease was induced by injection of spleen cells from B10.D2 mice into BALB/c mice deficient in mature T and B cells (recombination-activating gene 2 targeted). Dermal thickening, collagen deposition, vasoconstriction, and parameters of immunity were analyzed.Results. Similar to the human disease, this modified GVH model of SSc demonstrated evidence of dermal thickening, particularly in the extremities, progressive fibrosis of internal organs, vasoconstriction and altered expression of vascularity markers in skin and internal organs, early immune activation, inflammation in skin and internal organs, and autoantibody generation.Conclusion. This modified model of GVH-induced SSc exhibits all major components of human disease and is likely to contribute to better understanding of the disease mechanisms and, ultimately, improved treatments for patients.

Abstract. TGF-␤ is believed to play a central role in the development of Cyclosporin A (CsA)-induced nephropathy. This study investigated the effects of 1D11, a murine panspecific TGF-␤-neutralizing monoclonal antibody, in an ICR mouse model of chronic CsA nephropathy. Mice were administered a low-salt diet (0.01% sodium) for 1 wk followed by CsA treatment (30 mg/kg, subcutaneously, daily) for 4 wk. 1D11 was administered (2.5 mg/kg, intraperitoneally, 3 times/ wk) beginning immediately after the termination of CsA dosing and continued through 8 wk. CsA caused extensive renal histopathologic alterations, including tubular damage, interstitial infiltrates and fibrosis, deposition of collagen III, and apoptosis of tubular epithelial cells. 1D11 ameliorated the CsA-induced histopathologic alterations, with significant reduction in collagen III expression and deposition. Additionally, elevated levels of mRNA encoding TGF-␤1 and TGF-␤2 were significantly reduced. 1D11 also protected tubular epithelial cells from apoptosis by 48% (P Ͻ 0.05). In contrast, 13C4 (a control antibody) had no significant effect on any of the endpoints described above. Importantly, the effects of 1D11 on the CsA-induced morphologic alterations were followed by a reduction in serum creatinine level when compared with CsA mice treated with 13C4 (13C4, 0.45 Ϯ 0.09; 1D11, 0.30 Ϯ 0.08; P Ͻ 0.05) after 8 wk of treatment. Endothelial nitric oxide synthase (eNOS), inducible NOS (iNOS), nitrotyrosine, and tissue hypoxia were examined by immunostaining using specific antibodies. eNOS was significantly reduced in the endothelium of arterioles in the kidneys of mice treated with CsA, whereas iNOS was induced in the cortical tubules. Tissue hypoxia was found in both the arterioles and tubules, whereas nitrotyrosine was localized in the tubules. Administration of 1D11 improved tissue hypoxia and reduced nitrotyrosine formation. Moreover, the reciprocal changes in iNOS and eNOS expression were normalized by 1D11. This study demonstrates that 1D11 administration ameliorated morphologic alterations and preserved renal function in the context of existing chronic CsA nephropathy.