ABSTRACT
We developed a potentially novel and robust antibody discovery methodology, termed selection of phage-displayed accessible recombinant targeted antibodies (SPARTA). This combines an in vitro screening step of a naive human antibody library against known tumor targets, with in vivo selections based on tumor-homing capabilities of a preenriched antibody pool. This unique approach overcomes several rate-limiting challenges to generate human antibodies amenable to rapid translation into medical applications. As a proof of concept, we evaluated SPARTA on 2 well-established tumor cell surface targets, EphA5 and GRP78. We evaluated antibodies that showed tumor-targeting selectivity as a representative panel of antibody-drug conjugates (ADCs) and were highly efficacious. Our results validate a discovery platform to identify and validate monoclonal antibodies with favorable tumor-targeting attributes. This approach may also extend to other diseases with known cell surface targets and affected tissues easily isolated for in vivo selection.
Subject(s)
Antibodies, Monoclonal/immunology , Antibodies, Neoplasm/immunology , Antigens, Neoplasm/immunology , Breast Neoplasms/immunology , Heat-Shock Proteins/immunology , Lung Neoplasms/immunology , Receptor, EphA5/immunology , Animals , Antibodies, Monoclonal/therapeutic use , Antibodies, Neoplasm/isolation & purification , Antibodies, Neoplasm/therapeutic use , Antibody Affinity , Antibody Specificity , Bacteriophages , Breast Neoplasms/therapy , Cell Line, Tumor , Cell Surface Display Techniques , Cell Survival , Endoplasmic Reticulum Chaperone BiP , Female , High-Throughput Screening Assays , Humans , Immunoglobulin Variable Region/immunology , Immunotherapy , Lung Neoplasms/therapy , Mice , Plasmids , Proof of Concept Study , Recombinant Proteins , Saccharomyces cerevisiae , Xenograft Model Antitumor AssaysABSTRACT
Lung cancer is often refractory to radiotherapy, but molecular mechanisms of tumor resistance remain poorly defined. Here we show that the receptor tyrosine kinase EphA5 is specifically overexpressed in lung cancer and is involved in regulating cellular responses to genotoxic insult. In the absence of EphA5, lung cancer cells displayed a defective G1/S cell cycle checkpoint, were unable to resolve DNA damage, and became radiosensitive. Upon irradiation, EphA5 was transported into the nucleus where it interacted with activated ATM (ataxia-telangiectasia mutated) at sites of DNA repair. Finally, we demonstrate that a new monoclonal antibody against human EphA5 sensitized lung cancer cells and human lung cancer xenografts to radiotherapy and significantly prolonged survival, thus suggesting the likelihood of translational applications.
