This Nature Review Drug Discovery article looks like and is about RNA therapeutics, but what jumped out at me was the importance of the delivery system in the advance of RNA-based therapy. The delivery system should not only protect the therapeutic agent--whether it is mRNA, antisense oligonucleotides, or something else--from degradation, but also target specific tissues. The article mentions N-acetylgalactosamine conjugation, lipid nanoparticle (LNP), intrathecal injection, antibody conjugates, and peptide conjugates. Other delivery molecules being developed are aptamers and polymers.
Adding one more layer of novelty, Blakney et al. (2019) demonstrated that you could have self-amplifying RNA (saRNA) on the exterior of cationic LNP, which showed a higher transfection efficiency than saRNA encapsulated in LNP. It did not escape my notice that "LNP production at laboratory scale has encountered batch-to-bath variability."
The field of RNA therapeutics is much bigger, far more complicated, and thus much more interesting to follow than I expected.