What is the importance of Patisiran or Onpattro? « Back to Questions List

Patisiran is a new drug approved by the U.S. Food and Drug Administration (FDA). The drug  is based on a simple biological process called  RNA interference.  Patisiran is the first drug to be approved based on this process. The trade name of the drug is Onpattro. Alnylam Pharmaceuticals, a Cambridge company has won the permission for making patisiran.

The medicine will be used to treat a rare hereditary disease that causes loss of sensation, organ failure and even death.   This is caused when distorted proteins build up in the nerves, tissues and organs of an affected person.  Patisiran interferes with the formation of abnormal shapes and thus functions as a gene silencing drug. Around 50,000 people are estimated to be affected by this disease worldwide. 

Ribonucleic acid (RNA) is a polymeric molecule  that plays crucial roles in  various biological activities  in coding, decoding, regulation, and expression of genes. RNA and DNA  together with  lipids, proteins and carbohydrates, establish the four major macromolecules inevitable for all known forms of life.   RNA and DNA   are nucleic acids. Both are in the form of  chain of nucleotides.  DNA is often found as a paired double-strand. But, RNA takes the shape of a single-strand folded onto itself.  Cellular organisms use messenger RNA (mRNA) to convey genetic information that directs synthesis of specific proteins.  RNA molecules have active roles in controlling gene expression and communicating responses to cellular signals. RNA molecules are responsible for protein synthesis. Thus mRNA, translates DNA’s instructions into proteins. Many viruses too encode their genetic information using an RNA genome.

RNA interference (RNAi) is a biological process that prevents gene expression or translation by RNA molecules, by neutralizing targeted mRNA molecules. This process was also known by other names like co-suppression, post-transcriptional gene silencing (PTGS), and quelling. Since identification of  RNAi and its regulatory potentials, it  was clear that  RNAi can be used for suppression of desired genes. 

Patisiran uses specially designed pieces of RNA to silence mutated genes which if active in lever  can cause the hereditary disease. Patisiran and other RNA interference-based drugs under development use specially crafted snippets of artificial RNA to manipulate genes’ activity. In the recently concluded 18 month clinical trial, patients who received patisiran injections once in three weeks  showed a slight decrease in symptoms, whereas patients on the placebo worsened overall. The drug is not a cure, but prevents progression of the disease.  There are many other drugs under various stages which use RNA interference process. They will be used for treatment of diseases ranging from hemophilia to HIV. 

The launch of the drug  will have far reaching implications on treatment of many illnesses.  The discovery that RNA molecules can mute genes by interrupting the translation of DNA had won Nobel Prize. Through Patisiran, the discovery is being used for practical purposes. 
 

International Classification of Diseases (ICD) 

Proteins and their importance for living beings