It is the Breakthrough Event of 2022 in Medical science.
A girl with a resistant type of T cell leukaemia is successfully treated with base edited gene therapy for the first time in world and is now doing well.
Alyssa, a 13 year old girl from UK had T cell Leukaemia. She had undergone all available modes of treatment for leukaemia. Chemotherapy only aggravated her condition. Bone marrow transplantation is considered to be the final treatment of all Leukaemia. She got a relapse even after a successful Bone marrow Transplantation. There are no more means of treatment available. She did not have a single episode of disease free remission from the beginning of her disease.
T cell Leukaemia are the worst form of Blood leukaemia.
The main weapon of our body to fight cancer cells is T cells. Now, we know that T cells have a sense of what is our own and what is foreign. They seek out the cancer cells, label them as foreign and initiate our immune forces to destroy them. When there is a defect in our T cells, our body starts destroying our own thyroid cells or our skin cells starting a disastrous course. This is called Auto-Immune Disease. Here our own immune system destroys our own tissue. Alyssa had a disease where her own T cells have turned rogue and had become cancerous.
Leukaemia are difficult.
Leukaemia is also known as the cancer of the blood cells. There are as many type of Leukemias as the type of of blood cells we have. Each leukaemia of one can be as different from another’s as their fingerprint can be. For example, Our blood contains two type of cells, the Red cells and the White cells. Red cells carry oxygen while white cells constitute the defence force of our body. White cells are of two type- the Lymphocytes and the Myelocytes. Thus we can have Lymphatic Leukaemia or Myelocytic Leukaemia.
Now, the lymphocytes are of two types: B type cells or T cells. B lymphocytes produce antibodies against foreign things. For a long time, we didn’t know what is the role of T cells. Covid-19 taught us that the T cells are the band master of our immune system. They are like the National Security adviser of our body. They decide when and how our defence should act. They tell the body which bug is our own, which is foreign. They also set the quality and quantity of our immune reaction against viruses etc. They also fight the cancer cells.
When these T cells go rogue, it’s like our NSA getting infiltrated by the enemy. Who will fight T cell Leukaemia ? First your own T cells are cancerous. They won’t allow any foreign T cells to fight against your own T cell cancer. When you start chemo therapy against T cell leukaemia, you are basically killing your own T cells. Therefore the leukaemia of Alyssa didn’t respond, neither to Chemo therapy nor to a Bone marrow Transplantation.
Base Edited CAR T therapy:
In May 2022, Alyssa was enrolled for an experimental treatment, which is as audacious as it is outlandish, Base edited T cell therapy.
T cells are needed to fight leukaemia. But here the T cells of the patient have gone rogue. Doctors of University College of London decided to edit these T cells in their lab before injecting them into Alyssa’s blood. There are 4 edits.
T cells are harvested from healthy volunteers.
- The gene of these T cells are edited, so that they can by pass cross matching against Alyssa’s blood. The receptors for blood group was blanked out.
- A flag, CD7 was removed from these T cells. They won’t be recognised as T cell by the host cells.
- A flag, CD52 was removed. This will help these T cells survive powerful Chemo therapy against conventional T cells.
- Now these T cells have been battle ready. This time their gene is further edited to add a homing receptor that will home on to the cancer T cells of Alyssa.
All these changes are accomplished simply by editing the base pairs of the gene codon at the sub cellular level.
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Alyssa has been given a single injection of these Genetically Modified CAR T cells in may 2022.
She has been disease free since then, even 6 months after the injection. She didn’t have a single day of disease free remission up till then.
Base Editing is an advanced gene technique. It can produce a clone of cells that are genetically modified to suit our purpose. It is different from CRISPR technology. With its success in case of Alyssa, it opens up an era of curing point mutant defects like Sickle cell disorder or Cystic fibrosis, Duchenne’s Muscular Dystrophy , Phenyl Ketonuria cases by a single injection.
Can you believe it ! Here’s the link
I have included it in my list of the medical story of the year 2022.
Dr Ramakanta's Ideas 