Dual-ligand PROTACS mediate superior target protein degradation and therapeutic efficacy

• Published in: Chemical science (Cambridge) 2024-10, Vol.15 (42), p.17691-1771
• Main Authors: Chen, Yong, Xia, Zihan, Suwal, Ujjwal, Rappu, Pekka, Heino, Jyrki, De Wever, Olivier, De Geest, Bruno G
• Format: Article
• ISSN: 2041-6520; 2041-6539
• DOI: 10.1039/d4sc03555k

Proteolysis targeting chimeras (PROTACs) are revolutionizing the drug development landscape due to their unique ability to selectively degrade disease-associated proteins. Conventional PROTACs are bivalent entities that induce ubiquitination and subsequent proteolysis of a chosen protein of interest (POI) by forming a ternary complex with an E3 ligase. We hypothesized that dual-ligand PROTACs, featuring two copies each of a POI ligand and an E3 ligase ligand, would facilitate the formation of high-avidity, long-lived ternary complexes inside cells, thereby increasing POI degradation potency. To this end, we developed a convergent synthesis route, using l -aspartic acid as a building block for homodimer synthesis, followed by copper-catalyzed azide-alkyne cycloaddition (CuAAC) to conjugate both dimers through a flexible linker. Dual-ligand PROTACs achieved up to a tenfold increase in degradation efficiency and a hundredfold increase in cytotoxicity in vitro across various cancer cell lines compared to their single-ligand counterparts. Furthermore, dual-ligand PROTACs sustain prolonged protein degradation, up to 60 hours after pulsing and washout. In vivo , in a mouse tumor model, the superior therapeutic activity of dual ligand PROTACs was observed. Dual-ligand PROTACs which comprise of two copies of each E3 ligase ligand and targeted protein ligand display superior activity compared to conventional single-ligand PROTACs. The higher activity of dual-ligand PROTACs is enabled by the stabilized and long-lived ternary complex formation.