Anti-EphA2 Antibodies with Distinct In Vitro Properties Have Equal In Vivo Efficacy in Pancreatic Cancer

Abstract

The EphA2 receptor tyrosine kinase is overexpressed in a variety of human epithelial cancers and is a determinant of malignant cellular behavior in pancreatic adenocarcinoma cells. Moreover, it is expressed in tumor endothelium and its activation promotes angiogenesis. To better clarify the therapeutic potential of monoclonal antibodies (mAbs) directed to the EphA2 receptor, we generated a large number of mAbs by differential screening of phage-Ab libraries by oligonucleotide microarray technology and implemented a strategy for the rapid identification of antibodies with the desired properties. We selected two high-affinity and highly specific EphA2 monoclonal antibodies with different in vitro properties on the human pancreatic tumor cell line MiaPaCa2. One is a potent EphA2-agonistic antibody, IgG25, that promotes receptor endocytosis and subsequent degradation, and the second is a ligand antagonist, IgG28, that blocks the binding to ephrin A1 and is cross-reactive with the mouse EphA2 receptor. We measured the effect of antibody treatment on the growth of MiaPaCa2 cells orthotopically transplanted in nude mice. Both IgG25 and IgG28 had strong antitumor and antimetastatic efficacy. In vivo treatment with IgG25 determined the reduction of the EphA2 protein levels in the tumor and the phosphorylation of FAK on Tyr576 while administration of IgG28 caused a decrease in tumor vascularization as measured by immunohistochemical analysis of CD31 in tumor sections. These data show that in a pancreatic cancer model comparable therapeutic efficacy is obtained either by promoting receptor degradation or by blocking receptor activation.

Molecular markers associated with outcome and metastasis in human pancreatic cancer

“…EPHA2 , related to poor clinical outcome in PDAC, has already been successfully investigated as target in PDAC cell lines [30,31]. Indeed, in our study, EPHA2 was highly upregulated as PDAC with poor outcome, supporting its potential clinical relevance.…”

Structural and Functional Characterization of an Agonistic Anti-Human EphA2 Monoclonal Antibody

“…19 Therefore, additional studies will be important to fully understand the events that occur after binding of Fab 1C1 and lead to EphA2 activation. Our results have important implications for the design and generation of novel anti-tumor therapeutics targeting Eph receptors and exhibiting beneficial agonistic 26 or ephrin-blocking 29 properties.…”

“…Indeed, monoclonal antibodies (mAbs) targeting EphA2 have been shown to exhibit significant anti-tumor effects. [26][27][28][29] Several of these antiEphA2 mAbs inhibited malignant cell growth in various in vitro and in vivo preclinical models by inducing autophosphorylation, internalization, and degradation of the receptor. 26,27,29 However, a molecular understanding of their fine specificity and functional properties is limited by the lack of relevant structural data.…”

Novel human anti-claudin 1 mAbs inhibit hepatitis C virus infection and may synergize with anti-SRB1 mAb

“…Using this approach, we previously succeeded in generating human mAbs with in vitro and in vivo biological activity against the transferrin receptor, the ErbB2 and EphA2 tyrosine kinase receptors and the HCV receptor SRB1 (De Lorenzo et al, 2002;Catanese et al, 2007;Ansuini et al, 2009;Khalaj-Kondori et al, 2011).…”