SilencioM: silencing connected interfering oligonucleotides against MAPT as a potential disease modifying therapeutic for tauopathies

Tauopathies are a diverse group of neurodegenerative diseases whose pathogenesis involves brain accumulation of misfolded, pathological tau (Microtubule Associated Protein Tau, MAPT). More than twenty tauopathies have been identified thus far that collectively impact millions of people worldwide, of which the most common is Alzheimer's disease (AD). Despite substantial efforts to develop drugs for tauopathies, no effective treatments currently exist, highlighting the urgent need for therapeutics to combat these prevalent and ruinous neurodegenerative diseases. Strategies that target tau are likely to have the greatest impact since tau is the proximal cause of their pathogenesis. Small interfering RNAs (siRNAs) have emerged as a powerful class of precision therapeutics that silence disease-causing genes through RNA interference with favorable safety profiles. Delivery challenges are rapidly being addressed, and siRNA-based approaches are poised to transform the therapeutic landscape of neurological diseases. In this study, we describe SilencioM (Silencing connected interfering oligonucleotides against MAPT) and show its efficacy in markedly reducing tau pathology after a single intracerebroventricular injection in PS19 mice, a mouse model of severe tauopathy. SilencioM targets human, primate, rat and mouse ortholog genes; thus, the same compound can proceed from efficacy studies to Investigational New Drug Application (IND)-enabling studies. SilencioM is simple to manufacture and is administered without encapsulation in lipid nanoparticles and without requirements for lipophilic conjugation, making it a promising candidate for further development as a novel therapeutic for tauopathies, including AD.