Polarization of Tumor-Associated Neutrophil Phenotype by TGF-β: “N1” versus “N2” TAN

Many drugs that target transforming growth factor-β (TGFβ) signalling have been developed, some of which have reached Phase III clinical trials for a number of disease applications. Preclinical and clinical studies indicate the utility of these agents in fibrosis and oncology, particularly in augmentation of existing cancer therapies, such as radiation and chemotherapy, as well as in tumour vaccines. There are also reports of specialized applications, such as the reduction of vascular symptoms of Marfan syndrome. Here, we consider why the TGFβ signalling pathway is a drug target, the potential clinical applications of TGFβ inhibition, the issues arising with anti-TGFβ therapy and how these might be tackled using personalized approaches to dosing, monitoring of biomarkers as well as brief and/or localized drug-dosing regimens.

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Targeting the TGFβ signalling pathway in disease.

The distortion of growth factor signalling is the most important prerequisite in tumour progression. Transforming growth factor-beta (TGFbeta) signalling regulates tumour progression by a tumour cell-autonomous mechanism or through tumour-stroma interaction, and has either a tumour-suppressing or tumour-promoting function depending on cellular context. Such inherent complexity of TGFbeta signalling results in arduous, but promising, assignments for developing therapeutic strategies against malignant tumours. As numerous cellular context-dependent factors tightly maintain the balance of TGFbeta signalling and contribute to the regulation of TGFbeta-induced cell responses, in this Review we discuss how they maintain the balance of TGFbeta signalling and how their collapse leads to tumour progression.

TGFβ signalling: a complex web in cancer progression

Multiple myeloma is a plasma cell malignancy characterized by complex heterogeneous cytogenetic abnormalities. The bone marrow microenvironment promotes multiple myeloma cell growth and resistance to conventional therapies. Although multiple myeloma remains incurable, novel targeted agents, used alone or in combination, have shown great promise to overcome conventional drug resistance and improve patient outcome. Recent oncogenomic studies have further advanced our understanding of the molecular pathogenesis of multiple myeloma, providing the framework for new prognostic classification and identifying new therapeutic targets.

Understanding multiple myeloma pathogenesis in the bone marrow to identify new therapeutic targets

We have identified a new role for the matrix enzyme lysyl oxidase-like-2 (LOXL2) in the creation and maintenance of the pathologic microenvironment of cancer and fibrotic disease. Our analysis of biopsies from human tumors and fibrotic lung and liver tissues revealed an increase in LOXL2 in disease-associated stroma and limited expression in healthy tissues. Targeting LOXL2 with an inhibitory monoclonal antibody (AB0023) was efficacious in both primary and metastatic xenograft models of cancer, as well as in liver and lung fibrosis models. Inhibition of LOXL2 resulted in a marked reduction in activated fibroblasts, desmoplasia and endothelial cells, decreased production of growth factors and cytokines and decreased transforming growth factor-beta (TGF-beta) pathway signaling. AB0023 outperformed the small-molecule lysyl oxidase inhibitor beta-aminoproprionitrile. The efficacy and safety of LOXL2-specific AB0023 represents a new therapeutic approach with broad applicability in oncologic and fibrotic diseases.

http://basicmed.med.ncku.edu.tw/admin/up_img/0325-1.pdf

Allosteric inhibition of lysyl oxidase-like-2 impedes the development of a pathologic microenvironment.

Purpose: Transforming growth factor-β (TGF-β) suppresses tumor development by inhibiting cellular proliferation, inducing differentiation and apoptosis, and maintaining genomic integrity. However, once tumor cells escape from the tumor-suppressive effects of TGF-β, they often constitutively overexpress and activate TGF-β, which may promote tumor progression by enhancing invasion, metastasis, and angiogenesis and by suppressing antitumor immunity. The purpose of this study was to test this hypothesis using TGF-β pathway antagonists. Experimental Design: We examined the effects of selective TGF-β type I receptor kinase inhibitors, SD-093 and SD-208, on two murine mammary carcinoma cell lines (R3T and 4T1) in vitro and in vivo . Results: Both agents blocked TGF-β-induced phosphorylation of the receptor-associated Smads, Smad2 and Smad3, in a dose-dependent manner, with IC 50 between 20 and 80 nmol/L. TGF-β failed to inhibit growth of these cell lines but stimulated epithelial-to-mesenchymal transdifferentiation, migration, and invasiveness into Matrigel in vitro . These effects were inhibited by SD-093, indicating that these processes are partly driven by TGF-β. Treatment of syngeneic R3T or 4T1 tumor-bearing mice with orally given SD-208 inhibited primary tumor growth as well as the number and size of metastases. In contrast, SD-208 failed to inhibit R3T tumor growth or metastasis in athymic nude mice. Moreover, in vitro anti-4T1 cell cytotoxic T-cell responses of splenocytes from drug-treated animals were enhanced compared with cells from control animals. In addition, SD-208 treatment resulted in a decrease in tumor angiogenesis. Conclusion: TGF-β type I receptor kinase inhibitors hold promise as novel therapeutic agents for metastatic breast cancer.

https://clincancerres.aacrjournals.org/content/clincanres/12/14/4315.full.pdf

Inhibition of growth and metastasis of mouse mammary carcinoma by selective inhibitor of transforming growth factor-beta type I receptor kinase in vivo.

Normalizing the bone marrow microenvironment with p38 inhibitor reduces multiple myeloma cell proliferation and adhesion and suppresses osteoclast formation.

Inhibition of p38α MAPK Reduces Tumor Burden, Prevents the Development of Myeloma Bone Disease, and Increases Survival in the 5T2 and 5T33 Murine Models of Myeloma.

SCIO-469, a Potent and Selective Inhibitor of p38a MAPK, Normalizes the Bone Marrow Microenvironment and Inhibits Multiple Myeloma Cell Proliferation in In Vitro and In Vivo Models.

Andy Protter

Papers

Inhibition of growth and metastasis of mouse mammary carcinoma by selective inhibitor of transforming growth factor-beta type I receptor kinase in vivo.

Normalizing the bone marrow microenvironment with p38 inhibitor reduces multiple myeloma cell proliferation and adhesion and suppresses osteoclast formation.

Inhibition of p38α MAPK Reduces Tumor Burden, Prevents the Development of Myeloma Bone Disease, and Increases Survival in the 5T2 and 5T33 Murine Models of Myeloma.

SCIO-469, a Potent and Selective Inhibitor of p38a MAPK, Normalizes the Bone Marrow Microenvironment and Inhibits Multiple Myeloma Cell Proliferation in In Vitro and In Vivo Models.