**Abstract**

Nucleic acids are the backbone of antisense therapy. Antisense oligonucleotidebased therapeutics involves downregulation of gene expression. RNA-based drugs that include antisense oligonucleotides bear great therapeutic potential toward treatment of various diseases by altering RNA and/or reducing, restoring, and modifying protein expression through multiple molecular mechanisms. Pharmacology of targeted antisense therapy has provided the platform to translate its utility to the clinic. Over the years, chemical modifications of antisense oligonucleotides have not only enhanced the specificity and efficacy but also reduced the side effects. These have changed the whole clinical trial design and provide newer strategies for therapies. Improvement in antisense oligonucleotide therapy technology has allowed and brought research from bench to clinic. Additionally, the use of small interfering RNAs, micro RNAs, ribozymes, and other antisense compounds toward the treatment of deadly diseases like cancers have demonstrated both preclinical and clinical responses. Furthermore, antisense therapy has great potential to target specific genes of interest in the context of precision medicine. Optimization of enhanced delivery, specificity, affinity, and nuclease resistance with reduced toxicity is underway in different disease context. This chapter gives a complete overview of antisense therapy and highlights its potential. Here, we focused on the advances of the antisense technology, pharmacology, therapeutics, and drug discovery.

**Keywords:** antisense oligonucleotides, antisense therapy, antisense drug, antisense therapeutic, gene therapy
