For the first time, a new gene editing technology called base editing was used to modify immune cells and successfully treat a teen with treatment-resistant leukaemia.

 

What is it?

  • Bases are the language of life.
  • Just as letters in the alphabet spell out words that carry meaning, the billions of bases in one person’s DNA spell out the instruction manual for his/her body.
  • Base Editing treatment is a modification of chimeric antigen receptor, or CAR, T-cell therapy. But instead of using the CRISPR gene editing technique to modify the patient’s immune cells, the clinicians used the more precise base editing technique to alter donor immune cells.
  • With advances in genetic technology, scientists have been able to zoom into a precise part of the genetic code to alter the molecular structure of just one base, effectively changing its genetic instructions.
  • Those edited cells are given to the patient to “rapidly find and destroy T-cells” in the body, including leukemic T-cells.
  • Base editing is an even more precise gene editing technique than CRISPR and has fewer risks of unwanted effects on the chromosomes and thus less risk of side effects.

 

T-cell acute lymphoblastic leukaemia (T-ALL)

  • T-ALL affects the stem cells in the bone marrow that produce a particular kind of white blood cells (WBC) called T lymphocytes (T cells).
  • These cells provide a person immunity by killing cells carrying infections, activating other immune cells, and regulating the immune response.
  • At least 20% of these WBC are atypical – as they accumulate in the bone marrow, they crowd out “good” WBCs and hence weaken the immune system.
  • These unhealthy cells can also accumulate in other parts of the body like the liver, spleen and lymph nodes.
  • While found in both children and adults, T-ALL’s incidence decreases with age.
  • Treatment — Typical treatment for T-ALL is similar to that of any leukaemia– chemotherapy and stem cell/bone marrow transplant.