Inhibition of Cancer Cell Adhesion, Migration and Proliferation by a Bispecific Antibody that Targets two Distinct Epitopes on αv Integrins.

Members of the αv family of integrins regulate activation of transforming growth factor beta (TGFß) and are directly involved in pro-tumorigenic phenotypes. Thus, αv integrins may be therapeutic targets for fibrosis and cancer, yet the isolation of selective inhibitors is currently a challenge. We generated synthetic antibodies selective for αv integrins by phage display selections on cell lines that displayed integrin heterodimers. We identified antibodies that targeted two distinct epitopes on cell-surface αv integrins and partially inhibited cell adhesion mediated by interactions between integrins and the latency-associated peptide, part of the pro-form of TGFß. Using the isolated antibody paratope sequences we engineered a bispecific antibody capable of binding to both epitopes simultaneously; this antibody potently and completely inhibited cell adhesion mediated by integrins αvß1, αvß3 and αvß5. In addition, the bispecific antibody inhibited proliferation and migration of lung carcinoma lines, where the highest and lowest potencies observed correlated with integrin-αv cell surface expression levels. Taken together, our results demonstrate that phage display selections with live cells can yield high quality anti-integrin antibodies, which we used as biparatopic building blocks to construct a bispecific antibody that strongly inhibited integrin function and may be a therapeutic candidate for cancer and fibrosis.

Targeting the Wnt signaling pathway through R-spondin 3 identifies an anti-fibrosis treatment strategy for multiple organs.

The Wnt/ß-catenin signaling pathway has been implicated in human proliferative diseases such as cancer and fibrosis. The functions of ß-catenin and several other components of this pathway have been investigated in fibrosis. However, the potential role of R-spondin proteins (RSPOs), enhancers of the Wnt/ß-catenin signaling, has not been described. A specific interventional strategy targeting this pathway for fibrosis remains to be defined. We developed monoclonal antibodies against members of the RSPO family (RSPO1, 2, and 3) and probed their potential function in fibrosis in vivo. We demonstrated that RSPO3 plays a critical role in the development of fibrosis in multiple organs. Specifically, an anti-RSPO3 antibody, OMP-131R10, when dosed therapeutically, attenuated fibrosis in carbon tetrachloride (CCl4)-induced liver fibrosis, bleomycin-induced pulmonary and skin fibrosis models. Mechanistically, we showed that RSPO3 induces multiple pro-fibrotic chemokines and cytokines in Kupffer cells and hepatocytes. We found that the anti-fibrotic activity of OMP-131R10 is associated with its inhibition of ß-catenin activation in vivo. Finally, RSPO3 was found to be highly elevated in the active lesions of fibrotic tissues in mouse models of fibrosis and in patients with idiopathic pulmonary fibrosis (IPF) and nonalcoholic steatohepatitis (NASH). Together these data provide an anti-fibrotic strategy for targeting the Wnt/ß-catenin pathway through RSPO3 blockade and support that OMP-131R10 could be an important therapeutic agent for fibrosis.