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Selection of phage-displayed accessible recombinant targeted antibodies (SPARTA): methodology and applications
Sara D’Angelo, … , Andrew R.M. Bradbury, Renata Pasqualini
Sara D’Angelo, … , Andrew R.M. Bradbury, Renata Pasqualini
Published May 3, 2018
Citation Information: JCI Insight. 2018;3(9):e98305. https://doi.org/10.1172/jci.insight.98305.
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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 1

SPARTA methodology.

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SPARTA methodology.
(A) A naive human single-chain variable fragment (sc...
(A) A naive human single-chain variable fragment (scFv) library (~1 × 1011 transducing units [TU]) is screened in vitro against immobilized recombinant antigens. The phage output pool (~1 × 105 TU) is subsequently transferred to a yeast display vector for 2 additional screening steps. After rounds of positive and negative sorting, the yeast output pool (~1 × 104 TU) is expressed multivalently in phage particles and administered i.v. into tumor-bearing mice (n = 3). Tumor-homing phage particles are recovered, amplified by PCR, and reexpressed in multivalent format for 2 additional rounds of in vivo selection. After next-generation sequencing (NGS), clonal diversity and ranking are determined. (B and C) Flow cytometry profiles and ELISA. Positive binders are shown for selected anti-EphA5 or anti-GRP78. Each dot in the FACS plot represents an individual yeast antibody–displaying clone. ELISA performed with the corresponding recombinant antigen confirmed binding specificity. Open circles represent individual data points (n = 3). (D and E) Following in vitro screening steps, 3 rounds of in vivo selection occurred in mice bearing human lung cancer xenografts for EphA5 or isogenic mammary tumors for GRP78. Open circles represent individual data points (n = 3). Tumors 1 and 2 represent 2 independent experiments. Data represent ± SEM.

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