How gene therapy could cure cancer

How gene therapy could cure cancer

Subject :Science and Technology

Context:

Scientists in the United Kingdom testing a new form of cancer therapy, reported success in a teenaged girl, Alyssia, with a form of cancer called T-cell acute lymphoblastic leukaemia.

T-cell acute lymphoblastic leukaemia:

• T-cells are a class of white blood cells which are equipped to hunt and neutralise threats to the body.
• In this form of blood cancer, the T-cells turn against the body and end up destroying healthy cells that normally help with immunity.
• The disease is rapid and progressive and is usually treated by chemotherapy and radiation therapy.
• The new experimental gene therapy is relied on a new technique called ‘base editing.’ And proved successful on the teenaged cancer patient Alyssia.

What is base editing?

• A person’s genetic code is several permutations of four bases: Adenine (A), Guanin (G), cytosine (C) and thymine (T).
• Sequences of these bases, akin to letters in the alphabet, spell out genes that are instructions to produce the wide array of proteins necessary for the body’s functions.
• Editing these base sequences of genes with the help of a tool known as “CRISPR-cas9 system” is called ‘Base-editing’.
  • The CRISPR-cas 9 system, consists of an enzyme that acts like molecular scissors.
  • It can be made to cut a piece of DNA at a precise location and a guide RNA can be used to insert a changed genetic code at the sites of incision.
• David Liu, of the Broad Institute, Massachusetts has improvised on the CRISPR-cas9 system to be able to directly change certain bases: thus, a C can be changed into a G and T into an A.
• While still a nascent technology, base editing is reportedly more effective at treating blood disorders which are caused by so-called single point mutations, or when a change in a single base pair can cause terminal disease.

How did base-editing work for Alyssia’s therapy?

• In Alyssia’s case, her T-cells — perhaps because of a mis-arrangement in the sequence of bases — had become cancerous.
• A way to correct this mis-arrangement could mean a healthier immune system.
• With the help of Base-editing, scientists have successfully arranged the sequence bases which will produce healthier T-cells, which can further regrow her immune system.