Stapled peptide clinical trial

However, biologics have low bioavailability and cannot reach intracellular targets. Stapled peptides show an ability to inhibit intracellular PPIs that previously have been intractable with traditional small molecule or biologics, suggesting that they offer a novel therapeutic modality.

On the other hand, staple positioning is usually optimized via chemical synthesis and biophysical characterization of every possible variant of a peptide construct. However, these methods are by no means comprehensive and provide little insight about the behavior of a stapled construct in living cells [ ].

Moreover, experimental characterization of the stapled peptides is neither economically viable nor feasible within a reasonable timeline, especially for long peptides, and is considered tedious and expensive [ 65 , ]. At the same time, utilizing allows to efficiently build and characterize peptide candidates in silico. Thus, we are able to explore each possible staple location along the peptide backbone in order to ensure that each candidate is considered in the search.

All of these advantages reduce costs and time that are necessary to design and optimize the lead stapled peptide for detailed experimental studies [ 65 , ]. Several computational methods or techniques have been employed in stapled peptide design, including Energy minimization, Monte Carlo MC simulation and Molecular dynamics MD [ 65 ].

An example of a successful computational approach was the CCmut3 stapled peptide, a Bcr-Abl kinase agonist that effectively reduces the oncogenic potential of Bcr-Abl. By applying different in silico tools such as Chimera [ ], AmberTools15 [ ] and hydrogen mass repartitioning HMR for accelerating molecular dynamics MD simulations [ , ]; the authors were able to explore 64 peptide analogues with different possible positions of staple along peptide backbone.

Such models can be used to characterize a wider range of possibilities than was possible experimentally, due to CCmut3 peptide length, which is considered long. Additionally, the length of the peptide introduces a high degree of conformational variability and opportunity to be targeted by intracellular proteolytic mechanisms.

The authors concluded that computational methods can play a key role in the design process of therapeutics peptides, specifically in exploring an exceptionally large and diverse set of candidates in a short timeframe compared to experimental settings [ ].

Inhibiting protein-protein interactions PPI has become a general strategy for interpreting the molecular logic associated with PPI networks, or for therapeutic applications.

The later approach was explored extensively over the last ten years by introducing a new class of targeted inhibitors known as hydrocarbon-stapled peptides. Peptides originating from livestock and biological sources have low stability, short half-life and unstable secondary-structures due to their sensitivity toward proteolysis [ 1 , 16 ]. These impact peptide bioavailability and binding to their intracellular target interfaces, making peptides a poor drug candidate. However, small molecules are successful drug candidates due to their size, oral bioavailability and cell penetration.

Selected examples of these fruitful small-molecules drugs are Obatoclax GS which entered Phase II clinical trials in patients with small-cell lung cancer [ [] , [] , [] , [] ]; Nutlin and its derivatives [ ] led to the evolution of RG as a first MDM2 inhibitor that entered clinical trials in advanced solid tumor patients in A last example is a natural product Geldanamycin GM Fig.

Geldanamycin entered clinical trials and its clinical derivative, AAG , reached phases I and II trials in patients with multiple myeloma, lymphoma, stage IV pancreatic cancer, non-small-cell lung cancer and solid tumors [ ]. Crystal structures of successful small molecules inhibiting drug-target PPIs that have entered clinical trials.

Despite the success of small-molecules to perturb different PPIs, these traditional inhibitors are not sufficient to cover large interfaces, which are more likely amenable to peptidomimetics. Subsequently, synthetic and medicinal chemistry developments delivered stapling as a technique to overcome the limitation of native peptides in stability, resistance to proteolysis degradation, specificity to targets and cell penetration. Depending on the size of the targeted interface, the affinity of the interaction and the position of hot spots residues, different strategies have been generated to synthesize stapled peptides targeting major PPIs interfaces of previously undruggable protein networks.

All-hydrocarbon stapled peptides lead to the discovery of new candidate drugs, combining the advantages of small-molecules and biologics. As a result, stapling has found a unique therapeutic niche as an important class in the pharmaceutical field. Furthermore, scientific technology innovation and novel chemistry methodologies broaden therapeutic peptide diversity and improve their pharmaceutical properties.

In addition, advances in peptide screening and computational biology will continue to support peptide drug discovery. However, some obstacles need to be overcome to improve therapeutic properties, such as cellular penetration. Consequently, future studies should focus on the factors that promote cellular uptake and endosomal release in stapled peptide design.

Another challenge that must be overcome is the oral availability of peptide therapeutics, which could be boosted by increasing drug stability in the gastrointestinal tract, again by formulating peptide penetration with enhancers or congregating with carrier molecules or nanoparticles [ [] , [] , [] ]. Finally, in some cases, stapled peptides with high affinities do not necessary translate to the target cell, as Wallbrecher and Okamoto demonstrated when applying stapling to BimBH3 peptides to bind BCL-2 proteins and induce apoptosis [ , ].

To overcome this issue, the ReBiL platform has been developed by Li and co-workers to detect weak PPI interactions and mechanisms of drug action in living cells.

They revealed that potent binding in vitro does not necessarily correlate with higher intracellular PPI disruption activity. This emphasizes the importance of using an assay like ReBiL to analyze directly the disruption of target PPI within cells [ ]. Interestingly, relatively few reported high-resolution structures of stapled peptide in complex with their target interface reveal a direct interaction between the staple itself and residues of the protein interfaces Table 2.

Additionally, the staple can play a role in peptide penetration and bioactivity [ ]. Taken together, hydrocarbon-stapled peptides are a fertile ground for drug discovery. However, the development of highly cell-permeable and bioactive peptides is a challenging task that includes several phases.

Importantly, two questions need to be tackled in current research: Firstly, can a stapled peptide with significant in vitro results penetrate the cell membrane toward the target PPI complex? Secondly, if it reaches the target PPI, will this peptide exert the expected bioactivity in vivo?

This question could be addressed with future research aiming to tailored bioactive therapeutic peptides with high permeability and increased precision to PPIs within the targeted cell using advanced medicinal and synthetic chemistry in parallel with computational and drug delivery approaches. A was supported by Qatar leadership program, Qatar foundation.

National Center for Biotechnology Information , U. Comput Struct Biotechnol J. Published online Feb Ameena M. Author information Article notes Copyright and License information Disclaimer.

This article has been cited by other articles in PMC. Abstract Protein-protein interaction PPI is a hot topic in clinical research as protein networking has a major impact in human disease. Graphical abstract. Open in a separate window. Why Stapled Peptides? Chemical Synthesis of Stapled Peptides As the synthesis of bioactive-stapled peptides started to widen, the approaches used also branched and allowed stapled peptides to be applied for various purposes such as target binding analyses, structure determination, proteomic discovery, signal transduction research, cellular analyses, imaging, and in vivo bioactivity studies [ 31 ].

Reversible Reactions Using disulphide bridges between two Cys residues as stapling technique was first introduced by Schultz et al. Thioether Formation The reaction between Cys thiol and alpha-bromo amide groups has been developed as a protocol for peptide stapling by Brunel and Dawson [ 49 ]. Specific MCL-1 Stapled Peptide Inhibitor as Apoptosis Sensitizer in Cancer Cells The members of BCL-2 family known to have an anti-apoptotic role in cells are considered to be key pathogenic proteins in human diseases categorized by uncontrolled cell survival - such as cancer and autoimmune disorders.

Computational Approach for Staple Peptide Design Hydrocarbon stapled peptides are at a relatively early stage of development. Conclusion Inhibiting protein-protein interactions PPI has become a general strategy for interpreting the molecular logic associated with PPI networks, or for therapeutic applications.

References 1. Craik D. The future of peptide-based drugs. Chem Biol Drug Des. Rosenblum D. Omics-based nanomedicine: the future of personalized oncology.

Cancer Lett. Ruffner H. Human protein—protein interaction networks and the value for drug discovery. Drug Discov Today. Yan C. Characterization of protein-protein interfaces. Protein J. Verdine G. Elsevier Inc; Stapled peptides for intracellular drug targets. Druggable pockets and binding site centric chemical space: a paradigm shift in drug discovery.

Ivanov A. Targeting protein-protein interactions as an anticancer strategy. Trends Pharmacol Sci. Smith M. Features of protein—protein interactions that translate into potent inhibitors: topology, surface area and affinity. Expert Rev Mol Med. Fang Z. Future Med Chem. Gilson M.

Calculation of protein-ligand binding affinities. Annu Rev Biophys Biomol Struct. Bakail M. Targeting protein-protein interactions, a wide open field for drug design. C R Chim. Okamoto T. Further insights into the effects of pre-organizing the BimBH3 Helix. ACS Chem Biol. Bird G. Stapled HIV-1 peptides recapitulate antigenic structures and engage broadly neutralizing antibodies.

Nat Struct Mol Biol. Lau Y. Peptide stapling techniques based on different macrocyclisation chemistries. Chem Soc Rev. Jenssen H. Serum stability of peptides. Methods Mol Biol. Tsomaia N. Peptide therapeutics: targeting the undruggable space. Eur J Med Chem. Jubb H. Structural biology and drug discovery for protein-protein interactions. Lau J. Therapeutic peptides: historical perspectives, current development trends, and future directions. Bioorg Med Chem. Schafmeister C. An all-hydrocarbon cross-linking system for enhancing the helicity and metabolic stability of peptides [8] J Am Chem Soc.

Tyndall J. Proteases universally recognize beta strands in their active sites; pp. Nowick J. Acc Chem Res. Harrison R. Downsizing human, bacterial, and viral proteins to short water-stable alpha helices that maintain biological potency. Proc Natl Acad Sci. Kim Y. Nat Protoc. Blackwell H. Highly efficient synthesis of covalently cross-linked peptide helices by ring-closing metathesis.

Angew Chem Int Ed. Walensky L. Activation of apoptosis in vivo by a hydrocarbon-stapled BH3 helix. Ahrens V. Peptides and peptide conjugates: therapeutics on the upward path. Miller M. Cancer immunotherapy: present status, future perspective, and a new paradigm of peptide immunotherapeutics. Discov Med. Vlieghe P. Synthetic therapeutic peptides: science and market. Moreover, we report the results of two comparative studies upon different kinds of stapled-peptides, evaluating the properties given from each typology of staple to the target peptide and discussing the best choices for the use of this feature in peptide-drug synthesis.

Keywords: cellular uptake; helicity; peptide drugs; stapled peptide; structurally constrained peptide. For more information, please visit www.

About Aileron Therapeutics Aileron Therapeutics is creating one of the first new classes of drugs in 20 years. Contact: Pure Communications, Inc.