We report a methodology for the ribosomal synthesis of backbone-cyclized peptides involving genetic code reprogramming to introduce one or more nonproteinogenic amino acids. Expression of linear peptides bearing a cysteine-proline dipeptide sequence followed by glycolic acid results in self-rearrangement to a C-terminal diketopiperadine-thioester, which non-enzymatically generates a cyclized peptide. We demonstrate the ribosomal synthesis of several naturally occurring backbone-cyclized peptides and a library based on a bicyclic scaffold, and we identify bioactive sequences by screening and deconvolution.
Constrained peptides represent a new class of peptide molecules whose supramolecular structure is controlled via intramolecular covalent bonds, generally to confer upon them biochemical and/or physicochemical properties superior to those of ordinary peptides. Both academia and industry are showing increasing interest in constrained peptides, due to their promise as medicines and tools for drug discovery. The major categories of constrained peptides are macrocyclic peptides 1 and stapled peptides, 2 as illustrated in Figure 1. The related eld of foldamers, which can be thought of as conformationally constrained peptides, has been recently reviewed and will not be discussed here.3 This paper will present an overview of ongoing research and development efforts in this eld, with particular focus on our approach toward constrained peptide research and development. Why Study Constrained Peptides? PPI Drug TargetsMost investigational and approved drugs to date fall into the broad categories of small molecules or macromolecular biologics, with antibodies, proteins and vaccines representing the predominant forms of approved biologic therapies. Until recently, aside from a small number of natural products, there has been much less progress in designing drugs for the intervening space of medium sized molecules, de ned here as molecules with molecular weights ranging from 500 to 6000 Daltons.From the perspective of small molecule drug discovery, the FDA approval of Bcl 2 inhibitor venetoclax (Figure 2) in 2016, after nearly 30 years of research and development, dem- Abstract: Constrained peptides, namely macrocyclic and stapled peptides, are receiving increasing attention as a promising class of compounds for the inhibition of protein protein interactions (PPI). The current state of peptide therapeutics is discussed, including their merits and challenges, as well as recent technological developments that have enabled a new era in peptide research and development. The technology behind PeptiDream s Peptide Discovery Platform System (PDPS) is described, showing how it can be used to rapidly generate libraries of constrained peptides and obtain detailed SAR information. This technology can provide, with a high rate of success, potent peptide ligands that may be developed as drug candidates themselves, utilized in peptide drug conjugates (PDC), or converted into small molecule drug leads. The outlook for the eld of constrained peptides and their use in the clinic is also described.
Flexizymes are artificial RNA catalysts that enable us to readily prepare aminoacyl-tRNAs with a variety of amino acid and tRNA kinds. On the other hand, because their flexibility feature lacking high specificities toward amino acids and tRNAs, the in situ aminoacylation in a translation apparatus have not been able to executed. We here present a novel strategy to overcome this specificity problem to tRNA using a cis-acting flexizyme-tRNA construct, called a catalytic precursor tRNA, combining with a naturally occurring ribozyme, ribonuclease P (RNase P). In this coupling system of two RNA enzymes, self-aminoacylation occurs on the catalytic precursor tRNA for specific charging of amino acids at the 3'end of the tRNA domain in the presence of the cognate amino acid substrates. Subsequently, the aminoacylated catalytic precursor tRNA is specifically cleaved at the 5'linker region of the tRNA domain, giving the mature aminoacyl-tRNA. Most importantly, the generated flexizyme does not function in trans to tRNAs present in the translation apparatus, indicating that this two-ribozyme coupling system would potentially act as an orthogonal aminoacylation system in the translation apparatus.
Background: Antibody recruiting molecules (ARM) are novel, immunotherapeutic bifunctional molecules composed of two active termini connected by a linker. One of the termini binds to a target molecule on a cancer cell. The other terminus, called universal antibody binding terminus (uABT), recruit all endogenous IgG antibodies independent of their antigen binding specificity. As a result, the target cell is "opsonized" by antibodies which then bring the immune effector cells to eliminate the target through various antibody-dependent destruction mechanisms. Kleo Pharmaceuticals has developed a series of CD38-ARM mlecules which target human CD38 highly expressed by multiple myeloma cells. CD38-ARM compounds are able to mediate ADCC without depleting CD38 expressing immune effector cells like existing therapeutic antibodies such as Daratumumab. Methods: Cyclized peptides containing natural and non-natural amino-acid that selectively bind to human CD38 were identified using Peptidream Flexizyme-based, cell free Peptide Discovery Translation System. These peptides were linked to uABT antibody binder via a linker to generate the final CD38-ARM molecules Binding of CD38-ARM was tested by ternary complex formation between CD38 expressing cells, CD38-ARM and labelled human IgG1. To confirm the activity of CD38-ARM, surrogate CD16a binding and signaling assays were performed using the NFAT Promega system. Antibody dependent cellular cytotoxicity (ADCC) assays using purified NK cells from multiple donors with polymorphism variants (V/V, F/F, and V/F) of CD16a were performed to confirm activity. Live cell imaging was utilized to assess the dynamics of NK-RAJI cell interactions mediated by CD38-ARM +/- IgG. We evaluated the ability of compounds to mediate complement dependent cytotoxicity (CDC). We tested the effect of CD38-ARM on human immune cell populations within PBMC and whole bone marrow (WBM) by flow cytometry. Lastly, ex vivo samples from WBM of MM patients at diagnosis or relapse were used to evaluate CD38-ARM anti-tumor activity as well as off-target effects, without the addition of external source of IgG, through multiparametric flow-cytometry (CD45, CD19, CD38, CD138, CD56, CD27, CD8, CD117). Results: The CD38-ARM were shown to have the ability to bind to CD38 with a 7nM affinity and to human IgG1 and IgG2 with affinity of 15nM and 11nM by SPR. Activity of KP compounds was observed in all assays except for CDC. In ternary assay, KP-6 had an apparent EC50 of 16nM while KP-7's EC50 was 6nM. Both KP-6 and 7 had comparable EC50s in the single digit nanamolar range in the NFAT activation assay induced by CD16a binding was confirmed using human IgG to induce, while Daratumumab had an apparent EC50 of 0.04nM. In the ADCC assay, both KP-6 & KP-7 had EC50s of 7 & 6nM respectively, while Daratumumab had an EC50 of 0.1nM. In addition, no NK cell depletion was observed when PBMC were treated with KP compounds, whereas a profound reduction in both percentages and absolute numbers in this cell subset was observed with Daratumumab treatment. Increasing dose of CD38-ARM (range 0.1uM- 25uM) were tested in ex vivo WBM samples from MM patients together with a negative control and Daratumumab. At concentrations of 10uM and 25uM, CD38-ARM induced a significant reduction of MM cells achieving results comparable to those of Daratumumab activity (p >0.05 in both cases), while sparing all other CD38+ normal cells such as NK, T lymphocytes, monocytes and granulocytes, which are always reduced in the presence of Daratumumab. Conclusions: CD38-ARMs are able to kill MM cells by ADCC without depleting CD38 expressing immune cells contrary to existing antibodies such as Daratumumab. CD38-ARMs do not activate complement, which might be involved in the infusion reaction seen with Daratumumab. Most importantly, CD38-ARMs kill multiple myeloma cells ex vivo in patient bone marrow samples as well as plasma cell leukemia in patient blood. Combined with the in vivo efficacy data presented elsewhere, this data establishes the therapeutic potential of CD38-ARM. They also represent the first demonstration of the ARM platform ability to generate therapeutic agents tailored to a specific indication, by varying target binding moiety of the molecule. Disclosures Rossi: Kleo pharmaceuticals: Employment, Equity Ownership. Bunin:Kleo pharmaceuticals: Employment, Equity Ownership. Iben:Kleo Pharmaceuticals: Employment, Equity Ownership. Welsch:Kleo pharmaceuticals: Employment, Equity Ownership. Berbasova:Kleo Pharmaceuticals: Employment, Equity Ownership. Riillo:Kleo Pharmaceuticals: Research Funding. Ohuchi:Peptidream Inc.: Employment. Alvarez:Kleo pharmaceuticals: Employment, Equity Ownership. Kawakami:Peptidream Inc.: Employment. Nagasawa:Peptidream Inc.: Employment. Spiegel:Kleo pharmaceuticals: Equity Ownership. Rastelli:Kleo pharmaceuticals: Employment, Equity Ownership.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.