Nucleic Acid-Based Therapeutics Review 2024 PDF

Review: Nucleic Acid-based Therapeutics Nucleic acids as a therapeutic option Genentech proved that human proteins could be manufactured in bacteria using recombinant, synthetic DNA for the first time. Their initial product was somatostatin. Marvin Caruthers and Phosphoramidite Chem...

Review: Nucleic Acid-based Therapeutics Nucleic acids as a therapeutic option Genentech proved that human proteins could be manufactured in bacteria using recombinant, synthetic DNA for the first time. Their initial product was somatostatin. Marvin Caruthers and Phosphoramidite Chemistry (1980s) allowed for solid-state DNA/RNA synthesis, which is faster/easier than purely liquid-phase chemistry. Allows for synthesis of longer strands of nucleic acids – eventually helped with the human genome project. Antisense oligonucleotides (ASO) 1978 was shown that anti-sense DNA/RNA could block viral replication (targeted RSV). DNA or RNA nucleotides can be altered to be made into better “drugs” for our needs. Harder for the body to degrade,or more specific interactions with targets (less off-target effects). The first oligonucleotide drug, fomivirsen (Vitravene), developed by Ionis Pharmaceuticals and approved in 1998, treated cytomegalovirus retinitis in immunocompromised patients. It inhibited viral replication. Challenges to ASO-related treatments: liver/kidney toxicity, immune stimulation, stability (nucleases everywhere!), targeting the right cell or getting to the right cellular target. There are a few ASO-targed drugs FDA approved, and more in clinical trials. ASO’s Continued: Locked Nucleic Acids (LNAs) have been developed that stabilize the double-helix structure and contribute to ASO specificity and stability. Gapmer technology places RNA mimic LNAs around a target DNA to create an oligo that can bind to the targeted gene and recruit the cell’s own cleanup system, RNAse H, to degrade the target DNA of interest (therefore blocking protein expression). Many current Gapmer therapies like this target liver or mucsle diseases. Gapmer/LNAs have successfully treated diseases related to inappropriate mRNA splicing such as Duchenne muscular dystrophy (DMD) and Spinal muscular atrophy (SMA) RNA interference Small siRNA duplex in the cell binds cellular RISC (RNI-induced silencing complex), which then uses the siRNA to target the mRNA to be degraded (makes an siRNA/mRNA complex), then Argonaut (Argo) in the RISC complex degrades the target mRNA and therefore blocks protein production. This is a natural technique which works in many organisms, first discovered in C. elegans. siRNA can have off-target effects Nucleic acid drug delivery There have been significant improvements in nucleic acid drug delivery methods recently, including many novel ways to package the drugs (nanoparticles, nanotubules, bulky conjugates, exosomes, peptides, etc.). Many new drugs in clinical trials. CRISPR/Cas9 This technology uses another system to drive either deletions or insertions into the host cell genome. A “guideRNA” is transfected into a cell and helps the Cas9 enzyme find the target sequence in the genome. The guideRNA then binds to the genome and Cas9 creates a double-stranded break in the host DNA. The host cellular machinery repairs the break. The guideRNA is engineered to influence exactly how that repair occurs, and can lead to the insertion or deletion of genetic material. CRISPR/Cas9 has been used as a therapy for sickle-cell anemia, but has several drawbacks (see slide 39). mRNA therapeutics In addition to above, mRNA therapies have been used very successfully recently in vaccines for COVID-19 and other respiratory viruses. There are clinical studies trying to use mRNA vaccines against cancer. (see slide 40). Slide 45 has a good summary of the advantages and challenges of mRNA therapies.