Discovering and improving novel peptide therapeutics.
ABSTRACT Peptides have a number of advantages over small molecules in terms of specificity and affinity for targets, and over antibodies in terms of size. However, sensitivity to serum and tissue proteases coupled with short serum half-life has resulted in few recombinant library derived peptides, making the transition from lead to drug on the market. Recently, a series of technologies have been developed to address both these issues: selection methodologies addressing protease resistance have been developed that when combined with methods such as pegylation antibody Fc attachment and binding to serum albumin look likely to finally turn therapeutic peptides into a widely accepted drug class.
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Article: Biopharmaceuticals: an overview[Show abstract] [Hide abstract]
ABSTRACT: Biopharmaceuticals drugs structurally mimics compounds found within the body and are produced using biotechnologies. These have the potential to cure diseases rather than merely treat symptoms, and have fewer side effects because of their specificity, for example, cytokines, enzymes, hormones, clotting factors, vaccines, monoclonal antibodies, cell therapies, antisense drugs, and peptide therapeutics. Emerging technologies in the area of biopharmaceuticals include manufacture of monoclonal antibodies in protein free media, designing chemically defined cells, genome based technologies, improving vaccine manufacturing processes, a potential cancer treatment and non-ribosomal peptide synthesis. Biopharmaceuticals have changed the treatment ways of many diseases like diabetes, malignant disorders; since these can be tailored for specific medical problems in different individuals. With biotechnology, any drug can be genetically modified using cell fusion or deoxyribonucleic acid (DNA)-recombinant technologies to alter specificities for individual diseases. Some distinct advantages of biotechnological processes include fewer side effects and more potent effect on target cells. Biopharmaceuticalsû greatest potential lies in gene therapy and genetic engineering.
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ABSTRACT: Virus or tumor Ag-derived peptides that are displayed by MHC class I molecules are attractive starting points for vaccine development because they induce strong protective and therapeutic cytotoxic T cell responses. In thus study, we show that the MHC binding and consequent T cell reactivity against several HLA-A*02 restricted epitopes can be further improved through the incorporation of nonproteogenic amino acids at primary and secondary anchor positions. We screened more than 90 nonproteogenic, synthetic amino acids through a range of epitopes and tested more than 3000 chemically enhanced altered peptide ligands (CPLs) for binding affinity to HLA-A*0201. With this approach, we designed CPLs of viral epitopes, of melanoma-associated Ags, and of the minor histocompatibility Ag UTA2-1, which is currently being evaluated for its antileukemic activity in clinical dendritic cell vaccination trials. The crystal structure of one of the CPLs in complex with HLA-A*0201 revealed the molecular interactions likely responsible for improved binding. The best CPLs displayed enhanced affinity for MHC, increasing MHC stability and prolonging recognition by Ag-specific T cells and, most importantly, they induced accelerated expansion of antitumor T cell frequencies in vitro and in vivo as compared with the native epitope. Eventually, we were able to construct a toolbox of preferred nonproteogenic residues with which practically any given HLA-A*02 restricted epitope can be readily optimized. These CPLs could improve the therapeutic outcome of vaccination strategies or can be used for ex vivo enrichment and faster expansion of Ag-specific T cells for transfer into patients.Journal of immunology (Baltimore, Md. : 1950). 10/2014;
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ABSTRACT: Peptides constructed with the 20 natural amino acids are generally considered to have little therapeutic potential because they are unstable in the presence of proteases and peptidases. However, proteolysis cleavage can be idiosyncratic, and it is possible that natural analogues of functional sequences exist that are highly resistant to cleavage. Here, we explored this idea in the context of peptides that bind to the signaling protein Gαi1. To do this, we used a two-step in vitro selection process to simultaneously select for protease resistance while retaining function-first by degrading the starting library with protease (chymotrypsin), followed by positive selection for binding via mRNA display. Starting from a pool of functional sequences, these experiments revealed peptides with 100-400 fold increases in protease resistance compared to the parental library. Surprisingly, selection for chymotrypsin resistance also resulted in similarly improved stability in human serum (~100 fold). Mechanistically, the decreases in cleavage results from both a lower rate of cleavage (kcat) and a weaker interaction with the protease (Km). Overall, our results demonstrate that the hydrolytic stability of functional, natural peptide sequences can be improved by two orders of magnitude simply by optimizing the primary sequence.Scientific Reports 09/2014; 4:6008. · 5.08 Impact Factor