@article{barbieri_mollica_moore_sripada_shastry_kilgore_loudermilk_whitacre_kilgour_wuestenhagen_et al._2024, title={Peptide ligands targeting the vesicular stomatitis virus G (VSV-G) protein for the affinity purification of lentivirus particles}, volume={121}, ISSN={["1097-0290"]}, DOI={10.1002/bit.28594}, abstractNote={Abstract}, number={2}, journal={BIOTECHNOLOGY AND BIOENGINEERING}, author={Barbieri, Eduardo and Mollica, Gina N. and Moore, Brandyn D. and Sripada, Sobhana A. and Shastry, Shriarjun and Kilgore, Ryan E. and Loudermilk, Casee M. and Whitacre, Zachary H. and Kilgour, Katie M. and Wuestenhagen, Elena and et al.}, year={2024}, month={Feb}, pages={618–639} }
 @article{kilgore_chu_bhandari_fischler_carbonell_crapanzano_menegatti_2023, title={Development of peptide affinity ligands for the purification of polyclonal and monoclonal Fabs from recombinant fluids}, volume={1687}, ISSN={["1873-3778"]}, DOI={10.1016/j.chroma.2022.463701}, abstractNote={Engineered multi-specific monoclonal antibodies (msAbs) and antibody fragments offer valuable therapeutic options against metabolic disorders, aggressive cancers, and viral infections. The advancement in molecular design and recombinant expression of these next-generation drugs, however, is not equaled by the progress in downstream bioprocess technology. The purification of msAbs and fragments requires affinity adsorbents with orthogonal biorecognition of different portions of the antibody structure, namely its Fc (fragment crystallizable) and Fab (fragment antigen-binding) regions or the CH1-3 and CL chains. Current adsorbents rely on protein ligands that, while featuring high binding capacity and selectivity, need harsh elution conditions and suffer from high cost, limited biochemical stability, and potential release of immunogenic fragments. Responding to these challenges, we undertook the de novo discovery of peptide ligands that target different regions of human Fab and enable product release under mild conditions. The ligands were discovered by screening a focused library of 12-mer peptides against a feedstock comprising human Fab and Chinese hamster ovary host cell proteins (CHO HCPs). The identified ligands were evaluated via binding studies as well as molecular docking simulations, returning excellent values of binding capacity (Qmax ∼ 20 mg of Fab per mL of resin) and dissociation constant (KD = 2.16·10-6 M). Selected ligand FRWNFHRNTFFP and commercial Protein L ligands were further characterized by measuring the dynamic binding capacity (DBC10%) at different residence times (RT) and performing the purification of polyclonal and monoclonal Fabs from CHO-K1 cell culture fluids. The peptide ligand featured DBC10% ∼ 6-16 mg/mL (RT of 2 min) and afforded values of yield (93-96%) and purity (89-96%) comparable to those provided by Protein L resins.}, journal={JOURNAL OF CHROMATOGRAPHY A}, author={Kilgore, Ryan and Chu, Wenning and Bhandari, Dipendra and Fischler, David and Carbonell, Ruben G. and Crapanzano, Michael and Menegatti, Stefano}, year={2023}, month={Jan} }
 @article{chu_shastry_barbieri_prodromou_greback-clarke_smith_moore_kilgore_cummings_pancorbo_et al._2023, title={Peptide ligands for the affinity purification of adeno-associated viruses from HEK 293 cell lysates}, volume={7}, ISSN={["1097-0290"]}, DOI={10.1002/bit.28495}, abstractNote={Abstract}, journal={BIOTECHNOLOGY AND BIOENGINEERING}, author={Chu, Wenning and Shastry, Shriarjun and Barbieri, Eduardo and Prodromou, Raphael and Greback-Clarke, Paul and Smith, Will and Moore, Brandyn and Kilgore, Ryan and Cummings, Christopher and Pancorbo, Jennifer and et al.}, year={2023}, month={Jul} }
 @article{kilgore_minzoni_shastry_smith_barbieri_wu_lebarre_chu_o'brien_menegatti_2023, title={The downstream bioprocess toolbox for therapeutic viral vectors}, volume={1709}, ISSN={["1873-3778"]}, DOI={10.1016/j.chroma.2023.464337}, abstractNote={Viral vectors are poised to acquire a prominent position in modern medicine and biotechnology owing to their role as delivery agents for gene therapies, oncolytic agents, vaccine platforms, and a gateway to engineer cell therapies as well as plants and animals for sustainable agriculture. The success of viral vectors will critically depend on the availability of flexible and affordable biomanufacturing strategies that can meet the growing demand by clinics and biotech companies worldwide. In this context, a key role will be played by downstream process technology: while initially adapted from protein purification media, the purification toolbox for viral vectors is currently undergoing a rapid expansion to fit the unique biomolecular characteristics of these products. Innovation efforts are articulated on two fronts, namely (i) the discovery of affinity ligands that target adeno-associated virus, lentivirus, adenovirus, etc.; (ii) the development of adsorbents with innovative morphologies, such as membranes and 3D printed monoliths, that fit the size of viral vectors. Complementing these efforts are the design of novel process layouts that capitalize on novel ligands and adsorbents to ensure high yield and purity of the product while safeguarding its therapeutic efficacy and safety; and a growing panel of analytical methods that monitor the complex array of critical quality attributes of viral vectors and correlate them to the purification strategies. To help explore this complex and evolving environment, this study presents a comprehensive overview of the downstream bioprocess toolbox for viral vectors established in the last decade, and discusses present efforts and future directions contributing to the success of this promising class of biological medicines.}, journal={JOURNAL OF CHROMATOGRAPHY A}, author={Kilgore, Ryan and Minzoni, Arianna and Shastry, Shriarjun and Smith, Will and Barbieri, Eduardo and Wu, Yuxuan and Lebarre, Jacob P. and Chu, Wenning and O'Brien, Juliana and Menegatti, Stefano}, year={2023}, month={Oct} }
 @article{xiao_kilgore_sarma_chu_menegatti_hall_2022, title={<p>De novo discovery of peptide-based affinity ligands for the fab fragment of human immunoglobulin G</p>}, volume={1669}, ISSN={["1873-3778"]}, DOI={10.1016/j.chroma.2022.462941}, abstractNote={Antibody fragments and their engineered variants show true potential as next-generation therapeutics as they combine excellent targeting with superior biodistribution and blood clearance. Unlike full antibodies, however, antibody fragments do not yet have a standard platform purification process for large-scale production. Short peptide ligands are viable alternatives to protein ligands in affinity chromatography. In this work, an integrated computational and experimental scheme is described to de novo design 9-mer peptides that bind to Fab fragments. The first cohort of designed sequences was tested experimentally using human polyclonal Fab, and the top performing sequence was selected as a prototype for a subsequent round of ligand refinement in silico. The resulting peptides were conjugated to chromatographic resins and evaluated via equilibrium and dynamic binding studies using human Fab-κ and Fab-λ. The equilibrium studies returned values of binding capacities up to 32 mg of Fab per mL of resin with mild affinity (KD ∼ 10-5 M) that are conducive to high product capture and recovery. Dynamic studies returned values of product yield up to ∼90%. Preliminary purification studies provided purities of 83-93% and yields of 11-89%. These results lay the groundwork for future development of these ligands towards biomanufacturing translation.}, journal={JOURNAL OF CHROMATOGRAPHY A}, author={Xiao, Xingqing and Kilgore, Ryan and Sarma, Sudeep and Chu, Wenning and Menegatti, Stefano and Hall, Carol K.}, year={2022}, month={Apr} }
 @article{chu_prodromou_moore_elhanafi_kilgore_shastry_menegatti_2022, title={Development of peptide ligands for the purification of a-1 antitrypsin from cell culture fluids}, volume={1679}, ISSN={["1873-3778"]}, DOI={10.1016/j.chroma.2022.463363}, abstractNote={α-1 antitrypsin (AAT) deficiency, a major risk factor for chronic obstructive pulmonary disease, is one of the most prevalent and fatal hereditary diseases. The rising demand of AAT poses a defined need for new processes of AAT manufacturing from recombinant sources. Commercial affinity adsorbents for AAT purification present the intrinsic limitations of protein ligands - chiefly, the high cost and the lability towards the proteases in the feedstocks and the cleaning-in-place utilized in biomanufacturing - which limit their application despite their high capacity and selectivity. This work presents the development of small peptide affinity ligands for the purification of AAT from Chinese hamster ovary (CHO) cell culture harvests. An ensemble of ligand candidates identified via library screening were conjugated on Toyopearl resin and evaluated via experimental and in silico AAT-binding studies. Initial ranking based on equilibrium binding capacity indicated WHAKKSKFG- (12.9 mg of AAT per mL of resin), WHAKKSHFG- (16.3 mg/mL), and KWKHSHKWG- (15.8 mg/mL) Toyopearl resins as top performing adsorbents. Notably, the fitting of adsorption data to Langmuir isotherms concurred with molecular docking and dynamics in returning values of dissociation constant (KD) between 1 - 10 µM. These peptide-based adsorbents were thus selected for AAT purification from CHO fluids, affording values of AAT binding capacity up to 13 gram per liter of resin, and product yield and purity up to 77% and 97%. WHAKKSHFG-Toyopearl resin maintained its purification activity upon 20 consecutive uses, demonstrating its potential for AAT manufacturing from recombinant sources.}, journal={JOURNAL OF CHROMATOGRAPHY A}, author={Chu, Wenning and Prodromou, Raphael and Moore, Brandyn and Elhanafi, Driss and Kilgore, Ryan and Shastry, Shriarjun and Menegatti, Stefano}, year={2022}, month={Aug} }
 @article{chu_prodromou_day_schneible_bacon_bowen_kilgore_catella_moore_mabe_et al._2021, title={Peptides and pseudopeptide ligands: a powerful toolbox for the affinity purification of current and next-generation biotherapeutics}, volume={1635}, ISSN={["1873-3778"]}, DOI={10.1016/j.chroma.2020.461632}, abstractNote={Following the consolidation of therapeutic proteins in the fight against cancer, autoimmune, and neurodegenerative diseases, recent advancements in biochemistry and biotechnology have introduced a host of next-generation biotherapeutics, such as CRISPR-Cas nucleases, stem and car-T cells, and viral vectors for gene therapy. With these drugs entering the clinical pipeline, a new challenge lies ahead: how to manufacture large quantities of high-purity biotherapeutics that meet the growing demand by clinics and biotech companies worldwide. The protein ligands employed by the industry are inadequate to confront this challenge: while featuring high binding affinity and selectivity, these ligands require laborious engineering and expensive manufacturing, are prone to biochemical degradation, and pose safety concerns related to their bacterial origin. Peptides and pseudopeptides make excellent candidates to form a new cohort of ligands for the purification of next-generation biotherapeutics. Peptide-based ligands feature excellent target biorecognition, low or no toxicity and immunogenicity, and can be manufactured affordably at large scale. This work presents a comprehensive and systematic review of the literature on peptide-based ligands and their use in the affinity purification of established and upcoming biological drugs. A comparative analysis is first presented on peptide engineering principles, the development of ligands targeting different biomolecular targets, and the promises and challenges connected to the industrial implementation of peptide ligands. The reviewed literature is organized in (i) conventional (α-)peptides targeting antibodies and other therapeutic proteins, gene therapy products, and therapeutic cells; (ii) cyclic peptides and pseudo-peptides for protein purification and capture of viral and bacterial pathogens; and (iii) the forefront of peptide mimetics, such as β-/γ-peptides, peptoids, foldamers, and stimuli-responsive peptides for advanced processing of biologics.}, journal={JOURNAL OF CHROMATOGRAPHY A}, author={Chu, Wenning and Prodromou, Raphael and Day, Kevin N. and Schneible, John D. and Bacon, Kaitlyn B. and Bowen, John D. and Kilgore, Ryan E. and Catella, Carly M. and Moore, Brandyn D. and Mabe, Matthew D. and et al.}, year={2021}, month={Jan} }