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Selection of phage-displayed accessible recombinant targeted antibodies (SPARTA): methodology and applications
Sara D’Angelo, Fernanda I. Staquicini, Fortunato Ferrara, Daniela I. Staquicini, Geetanjali Sharma, Christy A. Tarleton, Huynh Nguyen, Leslie A. Naranjo, Richard L. Sidman, Wadih Arap, Andrew R.M. Bradbury, Renata Pasqualini
Sara D’Angelo, Fernanda I. Staquicini, Fortunato Ferrara, Daniela I. Staquicini, Geetanjali Sharma, Christy A. Tarleton, Huynh Nguyen, Leslie A. Naranjo, Richard L. Sidman, Wadih Arap, Andrew R.M. Bradbury, Renata Pasqualini
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Resource and Technical Advance Therapeutics

Selection of phage-displayed accessible recombinant targeted antibodies (SPARTA): methodology and applications

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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.

Authors

Sara D’Angelo, Fernanda I. Staquicini, Fortunato Ferrara, Daniela I. Staquicini, Geetanjali Sharma, Christy A. Tarleton, Huynh Nguyen, Leslie A. Naranjo, Richard L. Sidman, Wadih Arap, Andrew R.M. Bradbury, Renata Pasqualini

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Figure 5

Cytotoxic profile of anti-EphA5 and anti-GRP78 monoclonal antibodies.

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Cytotoxic profile of anti-EphA5 and anti-GRP78 monoclonal antibodies.
Cy...
Cytotoxicity was measured in real time in the presence of anti–human IgG Fc Fab fragments (secondary antibody) conjugated to monomethyl auristatin F (MMAF) or duocarmycin (DMDM) with a cleavable linker, and either emtansine (DM1) or amanitin (AAMT) with a noncleavable linker. Optimal concentrations of the secondary antibody drug conjugate (20 nM, or 1 ng/μl) was determined as the minimal concentration not inducing significant cell toxicity. (A–D) Treatment of cells with anti–EphA5 scFv-Fc in presence of secondary antibodies conjugated to AAMT, DMDM, MMAF, and DM1 induced potent cell death of EphA5-expressing cells. An isotype control scFv-Fc in the presence of secondary antibody conjugates showed no toxicity (blue line, 100% cell viability). (E–H) GRP78-targeted scFv-Fc were more effective at killing GRP78-expressing Ef43.fgf4 cells when in the presence of AAMT- or DMDM-conjugated secondary antibody drug conjugates, whereas control GRP78-silenced Ef43.fgf4 cells were not affected. An isotype control scFv-Fc in the presence of secondary antibody conjugates showed no toxicity (blue line, 100% cell viability).

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