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INNOSC Theranostics and
Pharmacological Sciences Designing miRNA ONTs for cardiometabolic pandemics

Table 4. Criteria selected to develop active cellular targeting Yang et al. 57,p.322 concluded that “miR-22 inhibitors may
miRNA ONTs have potential as candidate drugs for nonalcoholic fatty
liver disease (NAFLD) and obesity.” Kaur et al. reported
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Criteria Description abnormally high levels of miR-22-3p in the livers of db/db
1 Select a specific miRNA target that is unique, universal, mouse models of insulin resistance and Type 2 diabetes.
phylogenetically conserved, and significantly expressed in the
tissues and organs of interest to optimize the benefit/risk ratio. They showed that silencing miR-22-3p by antagomir
2 Replace the chemical modifications (phosphorothioate administration lowered random and fasting glucose in
and locked nucleic acid) utilized in generations 1 and 2 diabetic mice and improved glucose tolerance and insulin
compounds with a gamma peptide nucleic acid backbone to sensitivity. Hu et al. 59,p2 concluded that “reducing miR-22
avoid potential toxicities linked to specific chemical groups. enhances hepatic fibroblast growth factor 21 and activates
3 Optimize the backbone and nucleoside modifications to AMP-activated protein kinase, which could be a novel
increase resistance to nucleases and proteases/peptidases, approach to treat steatosis and insulin resistance.” In a
improving the ONT PK/PD profile. more recent study, Castano et al. reported that elevated
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4 Avoid chirality to increase the ONT purity, stability, PK/PD circulating miR-22-3p is a relevant biomarker for the
profile, and safety. stratification of patients with metabolic dysfunction-
5 Limit binding to serum proteins to favor uptake by the associated fatty liver disease (MAFLD). These authors
tissues and organs of interest before clearance/elimination by suggested that elevated circulating miR-22-3p levels may
the liver and kidneys. be used to identify patients with a high fatty liver index.
6 Optimize and simplify chemical synthesis to increase drug Panella et al. used knockout and transgenic mouse models
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purity and reduce the cost of goods. to report that miR-22 loss-of-function protects against
7 Conjugate the ONT to a fatty acid or a short peptide for obesity and hepatic steatosis, while its overexpression
enhanced and active targeted delivery to the tissues and
organs of interest, delivering a much-reduced therapeutic promotes both phenotypes even when mice are fed a regular
dose with an extended mean residence time. chow diet. These studies included the use of first- and
Abbreviations: PK/PD: Pharmacokinetic/pharmacodynamics; second-generation antagomirs. A biotechnology company
ONTs: Oligonucleotide therapeutics. (www.resalistherapeutics.com) is developing LNA/DNA
“mixmer” miR-22 antagomirs for the treatment of obesity.
program. The tissue specificity index (TSI) gives each One of their candidates is conjugated to GalNAc to treat
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non-coding RNA a value from 0 to 1, where 1 indicates metabolic dysfunction associated with steatohepatitis.
that the RNA is detected in only one specific tissue and 0
indicates it is detected in all tissues. While miRNAs show 4.2. Criterion 2: Avoid potential toxicities by
a broad range of TSI values, the TSI for hsa-miR-22-3p replacing PS and LNA chemical modifications
is 0.855, signifying an elevated tissue-specific expression utilized in generations 1 and 2 compounds with a
pattern, specifically in the adipocytes, myocardium, and gamma peptide nucleic acid (PNA) backbone
skeletal muscle. 56 The first generation of ONTs, already advanced into
We implemented a small throughput-high yield clinical trials, incorporated several medicinal chemistry
R and D strategy as an alternative to the classic modifications, including: 62-64
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high throughput screening strategy implemented by (i) PS backbone modifications, which were used to
pharmaceutical companies to find “hit compounds” from diminish nuclease degradation and augment plasma
libraries of millions of samples. Several in silico, in vitro, protein binding to promote tissue uptake.
and in vivo tools, we reported that miR-22-3p (a unique (ii) Gapmer oligodeoxynucleotides, which cause RNase H
miRNA evolutionarily conserved from flies to mammals) cleavage of the target RNA.
modulates several metabolic genes involved in lipid (iii) Ribose modifications (mainly 2’ position
oxidation, mitochondrial activity, energy expenditure, fat modifications, e.g., 2’-F, 2’-OMe, 2′-MOE, and 2’ –
accumulation, inflammation, and necrosis. 53,54 In animal 4’ LNA), which were used to increase stability and
studies, we demonstrated that miR-22-3p antagomirs specificity.
with first- and second-generation chemical modifications A panel of experts (DARTER group [https://
produced several metabolic improvements: Reduction of antisenserna.eu/]) recently published considerations in
fat mass without change of lean mass while food intake the preclinical assessment of the safety of ASOs. Based
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remained unchanged, improvement of glucose, cholesterol, on animal and human data, they suggested that blood
insulin sensitivity, and a marked reduction of liver steatosis. platelets and complement activation should be examined
In addition to our work, several other investigators have for PS-ASOs that renal and hepatic toxicities should be
independently confirmed the metabolic roles of miR-22. assessed for LNA gapmers. Therefore, alternative chemical

Volume 7 Issue 3 (2024) 5 doi: 10.36922/itps.3025