Accelerating the translation of oligonucleotide therapeutics by enhancing delivery - ABSTRACT Oligonucleotide therapeutics (ONTs) are poised to ignite a paradigm shift in what constitutes a “treatable” human disease. The FDA approval of life-changing ONTs like Spinraza (Ionis’ ASO therapy for spinal muscular atrophy), Onpattro (Alnylam’s siRNA therapy for hATTR amyloidosis), and the mRNA-based COVID-19 vaccines from Pfizer and Moderna that saved millions of lives demonstrate the profound potential impact ONTs can have on “undruggable” diseases. CRISPR-based editing strategies are now entering the clinic, with lipid nanoparticle-mediated delivery of mRNA encoding Cas9 variants offering an alternative to problematic viral vectors. Suppressor tRNAs that read through premature stop codons to restore proteins that were “lost in translation” are moving towards the clinic. Each of these ONTs faces a shared barrier to broad clinical translation: biological membranes. The large size (5-35 kD) and charged backbone of ONTs severely limits their ability to cross the plasma membrane. Even if the plasma membrane is crossed by promoting the endocytosis of the ONT, the endosomal membrane remains a highly effective barrier that prevents ONTs from reaching their targets in the cytosol and nucleus. Estimates are that only 1-3% of the ONT delivered to a patient reaches its target - the delivery stats are dismal for naked, ligand-conjugated, and LNP-encased ONTs. ONTs tend to accumulate in the liver, and most FDA-approved ONTs that are delivered systemically have liver targets. ONT conjugation to GalNAc, the ligand for the asialoglycoprotein receptor expressed on hepatocytes, improves delivery 30-fold. Other approved agents rely on local delivery to increase ONT exposure to a level sufficient to provide clinical value. However, not all tissues are suited for local delivery, many cell types with these tissues remain inaccessible to ONTs, and local delivery risks infection or damage to the target organ. There is thus a critical unmet need for strategies that improve the delivery of systemically administered ONTs to extrahepatic tissues. Until this need is met, a revolution in medical practice ushered in by nucleotide-based therapies will remain a dream unrealized. This proposal seeks a small molecule solution to the delivery problem. This strategy would be effective for multiple ONT platforms and disease agnostic. By drilling down on rigorous target validation from the outset, we hope to initiate a successful drug development program that takes the most direct path to the clinic. Our lead compounds diverge from status quo potentiators in that they dramatically increase ONT activity without causing endosomal damage, an effective, but prohibitively toxic, mode of action. The expected results would provide a solid foundation for funding a successful lead optimization program supported by target engagement assays and highlight the diseases most likely to rapidly realize the benefits of this approach.
