Table 3.

ASO chemical modifications and pharmacology profiles.

ASO Modification	Modification Type	Nuclease Resistance	RNAse H Cleavage	Target Affinity	Toxicity
Phosphorothioate (PS)	Phosphate	+	Yes	-	++
Phosphoramidate (NP)	Phosphate	+	No	+	+
Methyl-phosphonate (MP)	Phosphate	+	No	-	+
2′-O-methyl (2′-OMe)	Ribose	++	No	++	+ Reduced immune activation; less toxic than PS
2′-O-methoxyethyl (2′-MOE)	Ribose	++	No	++	+ Reduced immune activation; Less than 2′-OMe; less toxic than PS
Phosphorodiamidate morpholino (PMO)	Ribose phosphate	++	No	++	Safer
Locked nucleic acid (LNA)	Ribose	++	No	+++	+++
Constrained ethyl (cEt)	Ribose	+++	No	+++	++
Peptide nucleic acid (PNA)	Ribose phosphate	++	No	++	++ No immune activation