Gene Therapy to cure Cancer

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

• Alyssia was the first to receive experimental gene therapy that relied on a new technique called ‘base editing.’

What is T-cell acute lymphoblastic leukaemia?

• In this form of blood cancer, the T-cells, which are a class of white blood cells, equipped to hunt and neutralise threats to the body, 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.

What is ‘base editing?’

• A person’s genetic code is several permutations of four bases:
  • Adenine (A)
  • Guanin (G)
  • cytosine (C)
  • 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.
• In the last two decades, the world of biomedical engineering has been enthused by a technique that allows genes to be altered and errors ‘fixed.’
  • The most popular among these approaches has been the CRISPR-cas9 system.
    • Inspired by how certain bacteria defend themselves against viruses, by snipping out and storing pieces of their genes, 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 the incision.
    • While there are a few ways to effect such changes, the CRISPR-cas9 system is believed to be the fast, most versatile system to effect such gene editing.
  • 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.