Regulatory guidelines and preclinical tools to study the biodistribution of RNA therapeutics

The success of the messenger RNA-based COVID-19 vaccines of Moderna and Pfizer/BioNTech marks the beginning of a new chapter in modern medicine. However, the rapid rise of mRNA therapeutics has resulted in a regulatory framework that is somewhat lagging. The current guidelines either do not apply, do not mention RNA therapeutics, or do not have widely accepted definitions. This review describes the guidelines for preclinical biodistribution studies of mRNA/siRNA therapeutics and highlights the relevant differences for mRNA vaccines. We also discuss the role of in vivo RNA imaging techniques and other assays to fulfill and/or complement the regulatory requirements. Specifically, quantitative whole-body autoradiography, microautoradiography, mass spectrometry-based assays, hybridization techniques (FISH, bDNA), PCR-based methods, in vivo fluorescence imaging, and in vivo bioluminescence imaging, are discussed. We conclude that this new and rapidly evolving class of medicines demands a multi-layered approach to fully understand its biodistribution and in vivo characteristics.

Oligonucleotides to the (Gene) Rescue: FDA Approvals 2017-2019

Four decades have passed since oligonucleotides were first used to manipulate gene expression. There were few FDA approvals prior to 2016, mostly of drugs that eventually exhibited poor performance in the market. The aura of their younger siRNA relatives had also faded during the past 15 years. However, several FDA approvals have occurred in the past 4 years, restoring hope that a new era has dawned in oligonucleotide/siRNA clinical therapeutics. Here, we review the field of oligonucleotide therapeutics and provide an update on FDA approvals of oligonucleotides from 2017 until the second quarter of 2019. We take into consideration the ethical issues looming over the still somewhat limited efficacy of these molecules, the toxicity of treatment, and the exorbitant cost of these therapeutic agents, which limits accessibility for many.

Patisiran for the treatment of patients with familial amyloid polyneuropathy

Onpattro, also commonly known as patisiran, is a small interfering RNA (siRNA) molecule packaged within a lipid nanoparticle and is transported into the cell to target transthyretin gene (TTR) messenger mRNA (mRNA) by attaching to its complementary sequence. The target mRNA is degraded and both mutant and wild-type amyloid transthyretin (ATTR) protein production becomes suppressed. This drug was developed by Alnylam Pharmaceuticals to treat a rare disease called hereditary ATTR (hATTR) amyloidosis. This disease develops as a result of the deposition of toxic aggregates of misfolded TTR protein, and is progressive causing the affected individual to be bed bound and to eventually die if left untreated. However, variable expressivity and incomplete penetrance cause carriers of TTR gene variants to be asymptomatic for a prolonged time. The heterogeneity of symptoms makes correct diagnosis of the disease difficult, therefore management of symptoms and proper treatment are delayed as a result. However, certain TTR variants are found in endemic or cluster regions, which facilitates their detection. In this review paper, different aspects of the drug are discussed in detail, including its preclinical and clinical studies, as well as its pharmacokinetic properties along with drug interactions leading to its approval by the U.S. Food and Drug Administration (FDA) and the European Medicines Agency (EMA).

2018 FDA Tides Harvest

In 2018, the United States Food and Drug Administration (FDA) approved a total of 59 new drugs, three of them (5%) are TIDES (or also, -tides), two oligonucleotides and one peptide. Herein, the three TIDES approved are analyzed in terms of medical target, mode of action, chemical structure, and economics.