First all-D stapled peptides achieved cellular activity against the p53-Mdm2 cancer target with complete proteolytic stability — combining two complementary drug design strategies.
Two barriers solvedall-D amino acids provide complete enzyme resistance while stapling enables cell penetration — first combination achieving both
What the researchers found
The team started with a known all-D linear peptide that potently inhibits the p53-Mdm2 interaction in a test tube but cannot enter cells. Using computational modeling, they designed optimal staple placement to create macrocyclic versions.
The resulting stapled and stitched all-D peptides showed increased alpha-helical structure, improved binding to the Mdm2 target, complete resistance to proteolytic enzymes, and, most importantly, cellular activity.
This represents the first demonstration that combining D-amino acids with hydrocarbon stapling can produce peptides that are both enzyme-proof and cell-permeable, overcoming two of the biggest barriers to peptide drug development.
Why it matters
Peptide drugs face two main problems: enzymes break them down, and they cannot get into cells. D-amino acids solve the first problem but not the second. Stapling solves the second but not always the first. Combining both strategies simultaneously could open the door to a new class of highly stable, cell-permeable peptide therapeutics.
The p53-Mdm2 interaction is one of the most important targets in cancer research, and blocking it could reactivate the body's natural tumor suppressor.
The numbers in context
First all-D stapled peptides with cellular activity; complete proteolytic stability; improved helicity and binding
How the study worked
This was a laboratory study combining computational modeling and peptide chemistry. Researchers used molecular modeling to predict optimal staple positions on an all-D peptide scaffold. They synthesized stapled and stitched variants and tested them for helicity (circular dichroism), target binding, proteolytic stability, and cellular activity against the p53-Mdm2 interaction.
Who was studied
Synthetic peptides tested in cell-based assays
What this study cannot tell us
This is an early proof-of-concept study. The cellular activity was demonstrated but detailed potency data, selectivity profiling, and in vivo testing were not reported.
Whether this combined strategy works for targets beyond p53-Mdm2 remains to be seen.
How to read the evidence
Preliminary evidence from proof-of-concept cell-based studies. Cellular activity demonstrated but detailed potency and in vivo data not reported.
When this study was published
Published in 2020. The dual D-amino acid + stapling strategy continues to be developed.
The bigger picture
Peptide drugs face two fundamental challenges: enzyme degradation and cell membrane penetration. Combining D-amino acids and stapling addresses both simultaneously, creating a platform for developing peptide drugs that are stable in the body and can reach intracellular targets.
Questions still open
- Does the combined strategy work for peptide targets beyond p53-Mdm2?
- What is the in vivo pharmacokinetics of all-D stapled peptides?
- Can these be manufactured at scale for clinical development?
Common questions
Why use D-amino acids in drugs?
What does stapling add?
Read the original research
Macrocyclization of an all-d linear α-helical peptide imparts cellular permeability.
Chemical science, 11(21), 5577-5591
Citation
Kannan, Srinivasaraghavan; Aronica, Pietro G A; Ng, Simon; Gek Lian, Dawn Thean; Frosi, Yuri; Chee, Sharon; Shimin, Jiang; Yuen, Tsz Ying; Sadruddin, Ahmad; Kaan, Hung Yi Kristal; Chandramohan, Arun; Wong, Jin Huei; Tan, Yaw Sing; Chang, Zi Wei; Ferrer-Gago, Fernando J; Arumugam, Prakash; Han, Yi; Chen, Shiying; Rénia, Laurent; Brown, Christopher J; Johannes, Charles W; Henry, Brian; Lane, David P; Sawyer, Tomi K; Verma, Chandra S; Partridge, Anthony W. (2020). Macrocyclization of an all-d linear α-helical peptide imparts cellular permeability.. Chemical science, 11(21), 5577-5591. https://doi.org/10.1039/c9sc06383h