To further assess the pipeline dynamics, the above collected RNA therapeutics (Supplement Table ) were then categorized based on their targeting diseases and development status (Figure ). Cancer has attracted the highest number of therapeutics and vaccines in the research phase, with infectious diseases at the second. Neurological and neuromuscular diseases have the most approved treatments on the market, followed by cardiovascular and infectious diseases. The COVID-19 pandemic quickly catapulted RNA therapeutics for infectious diseases in both the research phase and approved vaccines to the forefront. While diseases such as familial hypercholesterolemia and DMD have multiple approved RNA therapeutics, blood diseases, cancers, and respiratory diseases currently do not have any approved RNA treatments. Respiratory disease, autoimmune disease, and blood diseases have the highest percentage of therapeutics in preclinical trials but so far have no approved treatments. Figure shows the percentages of RNA therapeutics in various development stages based on disease type, revealing places with high activities, as well as places needing more attention. Figure . Counts of potential therapeutics and vaccines in different development stages (preclinical, clinical, completed, withdrawn, and approved) for various disease types. A full list of clinical trials is provided in Supplemental Table . Cardiovascular diseases, which account for 32% of all deaths, are the leading cause of death worldwide, taking an estimated 17.9 million lives each year. Cardiovascular diseases include disorders of the heart and blood vessels. Over 80% of cardiovascular disease deaths are due to heart attacks and strokes, and one-third of these deaths occur prematurely in people under 70 years of age. There are two current drugs, Kynamro and Leqvio, approved for the treatment of the cardiovascular disease, familial hypercholesterolemia. In 2013, Ionis Pharmaceuticals received US FDA approval for their ASO drug Kynamro that targets apolipoprotein B. However, Kynamro has serious hepatotoxicity risk and patients prescribed the drug are monitored closely. The Novartis siRNA therapy drug Leqvio (developed by Alnylam) requires only two doses per year, and it received US FDA approval very recently in December 2021. Leqvio targets proprotein convertase subtilisin kexin type 9 (PCSK9) to lower LDL cholesterol. Leqvio is a trivalent N-acetylgalactosamine (GalNAc)-conjugated siRNA with three GalNAc molecules clustered and conjugated to one siRNA molecule (Figure ). In addition to those approved ones, there are several more RNA therapeutics for cardiovascular diseases currently in the clinical trial stages. Silence Therapeutics is evaluating the siRNA product SLN360 in a phase I clinical trial for its safety, tolerance, and pharmacodynamic and pharmacokinetic response in individuals with high lipoprotein A (LpA) cardiovascular disease. By targeting the LPA gene, SLN360 lowers the levels of LpA, decreasing the risk of heart disease, heart attacks, and strokes. Alnylam is also evaluating the siRNA product Zilebesiran that targets angiotensinogen for sustained reduction of hypertension. Interim phase I results show >90% reduction in serum angiotensinogen (AGT) for 12 weeks at a dosage of 100 mg or greater given quarterly or biannually. This dosing regimen and the continued efficacy and safety of the drug are being evaluated in a phase II study initiated in June 2021 (NCT04936035). Zilebesiran also uses Alnylam's trivalent GalNAc-conjugated siRNA delivery platform (Figure ). AstraZeneca and Moderna are collaborating on the mRNA drug AZD8601 to treat ischemic heart disease. 144 AZD8601 targets vascular endothelial growth factor-A (VEGF-A). When AZD8601 is injected into the epicardium, VEGF-A is produced close to the damaged heart muscle, allowing cardiac regeneration. 146 Metabolic diseases affect over a billion people worldwide by causing too much or too little of essential substances in the body. Diabetes alone affects 422 million people worldwide, causing 1.5 million deaths annually. Waylivra, an ASO product targeting apolipoprotein C-III (apoC-III) by Ionis Pharmaceuticals, received European Union (EU) approval in 2019 as a treatment for familial chylomicronemia syndrome (FCS). 152 FCS is a disease that prevents the body from breaking down consumed triglycerides. ApoC-III protein, which is produced in the liver, regulates plasma triglyceride levels in FCS patients, and Waylivra (volanesorsen) reduces its mean plasma levels. 153 IONIS-GCGRRx is another ASO product developed by Ionis Pharmaceuticals and treats diabetes by reducing the production of the glucagon receptor (GCGR). Glucagon is a hormone that opposes the action of insulin and stimulates the liver to produce glucose, particularly in patients with type-2 diabetes. Alpha-1 antitrypsin deficiency (AATD) is a hereditary metabolic disease. Alpha-1 antitrypsin (AAT) is a glycoprotein produced in the liver that travels through the bloodstream to protect the lungs from inflammation. Mutations in the SERPINA1 gene cause a deficiency of AAT in the blood, leading to toxic effects in the lungs and the accumulation of high levels of AAT in the liver that cause liver damage. 156 ARO-ATT, a siRNA product developed by Arrowhead Pharmaceutical, targets the SERPINA1 mutation, and in preclinical studies has shown promise in reducing AAT liver disease. Beam Therapeutics is developing a CRISPR base editing drug to treat AATD by correcting the E342K mutation in the SERPINA1 gene. Beam's base editor has two main components, a CRISPR protein bound to a guide RNA and a base editing enzyme, which are fused to form a single protein. This fusion allows the precise targeting and editing of a single base pair of DNA, which has not been previously achieved. Repairing the mutation would restore normal gene function and eliminate abnormal AAT production. This editing system uses a non-viral lipid nanoparticle delivery system. Methylmalonic acidemia (MMA) is a hereditary metabolic disease in which the body is unable to metabolize certain proteins and lipids correctly. Liver diseases affect more than 1.5 billion people worldwide 165 and account for over 2 million deaths per year. The siRNA therapeutic GIVLAARI, developed by Alnylam, received FDA approval in 2019 for the treatment of acute hepatic porphyria. Acute hepatic porphyria is a genetic disease characterized by life-threatening acute attacks and chronic pain. 167 GIVLAARI is the first approved GalNAc-conjugated RNA therapeutic. Non-alcoholic steatohepatitis (NASH) is an accumulation of fat in the liver that causes liver damage. The antisense therapeutic ION839/AZD2693 from Ionis/AstraZeneca entered phase I trials in 2020 in patients with NASH and fibrosis. 169 AZD2693/ION839 targets patatin-like phospholipase domaincontaining 3 (PNPLA3), reducing its expression. Mutation of PNPLA3, which produces a protein that accumulates on the surface of intracellular lipid droplets, is strongly associated with an increased risk for NASH. 170 Cancer includes a large group of diseases that are characterized by abnormal cell growth in various parts of the body. It is the second leading cause of death globally, accounting for an estimated 10 million deaths per year with over 19 million new cases diagnosed in 2020. Currently there are no approved RNA therapeutics for cancer treatment. NOXXON Pharma's lead aptamer candidate NOX-A12 is in development as a combination therapy for multiple types of cancers. It is intended to enhance other anti-cancer treatments without side effects. A phase I/II trial of NOX-A12 in combination with radiotherapy in newly diagnosed brain cancer patients who would not benefit from standard chemotherapy is ongoing. Interim data from the study in June 2021 showed tumor reduction in five of six patients consistent with an anti-cancer immune response, and there were no unexpected adverse events. NOXXON is collaborating with Merck in their pancreatic cancer program. NOXXON, in a phase I/II combination trial with Merck's Keytruda, reported success in treating metastatic pancreatic and colorectal cancer and entered a second collaboration with Merck to conduct a phase II study in pancreatic cancer patients. 174 NOX-A12 targets C-X-C motif chemokine ligand 12 (CXCL12) 173 , which, with its receptors, acts as a link between tumor cells and their environment, promotes tumor proliferation, new blood vessel formation, and metastases, and inhibits cell death. The anti-cancer siRNA product, STP707 by Sirnaomics 176 , targets TGF-β1 and COX-2 mRNAs. A preclinical study demonstrated that knocking down TGF-β1 and COX-2 gene expression simultaneously in the tumor microenvironment increases active T cell infiltration and combining the two siRNAs produces a synergistic effect that diminishes pro-inflammatory factors. Descartes-11 developed by Cartesian is a CAR T-cell therapy for treating multiple myeloma, a white blood cell cancer that affects plasma cells. It is currently in phase II studies with newly diagnosed patients. Descartes-11 contains autologous CD8 + T cells engineered with RNA chimeric antigen receptors (CARs) that bind to B-cell maturation antigen (BCMA). BCMA is highly expressed in all myeloma cells, and Descartes-11 binds and kills BCMA-positive myeloma cells. 178 Infectious diseases are caused by bacteria, viruses, fungi, or parasites. The first antisense antiviral, Vitravene, approved for use in 1998, treats cytomegalovirus (CMV) retinitis. It was developed to treat the large number of cases of CMV retinitis in patients with acquired immunodeficiency syndrome (AIDS). After the introduction of highly active antiretroviral therapy (HAART), the incidence of CMV retinitis decreased and Vitravene was withdrawn in the US in 2001. However, it paved the way for other drugs in its class, proving the clinical efficacy of ASO therapeutics. SARS-CoV-2 has infected over 280 million people, causing over 5.4 million deaths worldwide. The COVID-19 pandemic brought the first approved mRNA vaccine to market. BioNTech/Pfizer's COVID-19 BNT162/Comirnaty vaccine was given US FDA emergency use authorization in 2020 and approved by the FDA in 2021. Moderna's COVID-19 mRNA-1273/Spikevax vaccine was also given US FDA emergency use authorization in 2020. Globally over 9 billion COVID-19 vaccine doses have been administered. Arbutus Biopharma Corporation developed AB-729, an RNA interference (RNAi) therapeutic specifically designed to reduce all hepatitis B virus (HBV) antigens, including hepatitis B surface antigen (HBsAg). HBsAg interferes with host immune response 191 , and preliminary data indicate that longterm suppression of HBsAg with AB-729 results in an increased HBV-specific immune response. Moderna's first quadrivalent seasonal influenza mRNA vaccine candidate mRNA-1010 is in phase I/II trials. 144 mRNA-1010 targets influenza lineages recommended by the World Health Organization (WHO) for the prevention of influenza, including seasonal influenza A H1N1 and H3N2 and influenza B Yamagata and Victoria. Moderna has also developed a vaccine for RSV 144 , a common respiratory virus that can cause serious illness in infants and older adults. Moderna's mRNA-1345 is currently in a phase I trial to evaluate its tolerance and reactogenicity in children, younger adults, and older adults. CureVac also has an mRNA prophylactic vaccine for RSV in their pipeline 136 that is in pre-clinical development. 136 Neuromuscular diseases affect the function of muscles and nerves that communicate sensory information to the brain. They affect the brain as well as the nerves found throughout the body and the spinal cord. These types of diseases have the greatest number of approved RNA therapeutics. There are two approved treatments for DMD: Sarepta's ASO therapeutics Exondys 51, which targets exon 51 of the dystrophin gene, was FDA approved in 2016 and Vyondys 53, which targets exon 53 of the dystrophin gene, was FDA approved in 2019. Ionis Pharmaceuticals received FDA approval in 2016 for ASO therapeutic Spinraza targeting survival of motor neuron 2 (SMN2) for the treatment of spinal muscular atrophy. Their second therapeutic approved by the FDA in 2018 was the ASO neurological therapeutic Tegsedi, which targets hepatic production of transthyretin (TTR) and is used for the treatment of hATTR amyloidosis-polyneuropathy a disease due to mutations in the gene encoding TTR that leads to abnormal amyloid deposits on nerves. Onpattro by Alnylam is another approved RNA drug for the treatment of hATTR amyloidosis-polyneuropathy by targeting hepatic production of transthyretin. Onpattro, which was FDA approved in 2018, was the first siRNA drug. Sarepta Therapeutics has two other ASO therapeutics for the treatment of DMD, SRP-5044 and SRP-5050 (targeting exon 44 and exon 50 of the dystrophin gene, respectively) that are in preclinical studies. Amyotrophic lateral sclerosis (ALS) is a progressive neurodegenerative disease that affects nerve cells in the brain and spinal cord. Ionis Pharmaceuticals in partnership with Biogen has an ASO investigational drug Tofersen in phase III clinical trials. Tofersen targets superoxide dismutase 1 (SOD1), the second most common and best understood genetic cause of ALS.