Development of N-Terminally Modified Variants of the CXCR4-Antagonistic Peptide EPI-X4 for Enhanced Plasma Stability
Mirja Harms, Rikke Fabech Hansson, Andrea Gilg, Yasser Almeida‐Hernández, Jessica Löffler, Armando Rodríguez, Monica Habib, Dan Albers, Nermin S. Ahmed, Alireza Abadi, Gordon Winter, Volker Rasche, Ambros J. Beer, Gilbert Weidinger, Nico Preising, Ludger Ständker, Sebastian Wiese, Elsa Sánchez‐García, Alexander N. Zelikin, Jan Münch
Abstract
High Resolution Image Download MS PowerPoint Slide EPI-X4, a natural peptide CXCR4 antagonist, shows potential for treating inflammation and cancer, but its short plasma stability limits its clinical application. We aimed to improve the plasma stability of EPI-X4 analogues without compromising CXCR4 antagonism. Our findings revealed that only the peptide N-terminus is prone to degradation. Consequently, incorporating d -amino acids or acetyl groups in this region enhanced peptide stability in plasma. Notably, EPI-X4 leads 5, 27, and 28 not only retained their CXCR4 binding and antagonism but also remained stable in plasma for over 8 h. Molecular dynamic simulations showed that these modified analogues bind similarly to CXCR4 as the original peptide. To further increase their systemic half-lives, we conjugated these stabilized analogues with large polymers and albumin binders. These advances highlight the potential of the optimized EPI-X4 analogues as promising CXCR4-targeted therapeutics and set the stage for more detailed preclinical assessments.