In 2019, it was estimated that about 6% of the world’s population, adults and kids, are affected by cancer. Now, imagine if it were possible for a teenager with aggressive leukemia to suddenly have no more detectable cancer cells in their body. You wouldn’t think this is possible, right? However, this was indeed proven possible when a 13 year old patient, named Alyssa, received a new experimental treatment involving CRISPR gene editing that genetically tweaked her immune cells.

Immune System

Currently, Alyssa seems to be in remission but will continued to be closely monitored to guarantee she is fully cancer free. Alyssa had undergone chemotherapy and a bone marrow transplant previously, but with these treatments the cancer continued to come back.  At that point her only option remaining was palliative care to relive her symptoms, but this could not get rid of the cancer. Alyssa was the first ever patient to receive the new treatment.

Alyssa diagnosis was T-cell acute lymphoblastic leukemia (also known as T-ALL) in May of 2021.  T-ALL is the most common form of pediatric cancer. It is a type of blood cancer that begins in the bone marrow and can spread throughout other organs. T-ALL affects the stem cells in the bone marrow that produce white blood cells called T lymphocytes (T-cells) that guard the body against infection. At least 20% of white blood cells, or T-cells, in people with T-ALL are abnormal, and these abnormal white blood cells crowd out the normal immune cells and weaken the immune system.

The two most common treatments for T-ALL are chemotherapy, which kills the cancer cells, and a bone marrow transplant, which replaces the patients diseases bone marrow stem cells with healthy ones from donors. However, as we already discusses neither of these treatments worked for Alyssa.

Another treatment that sometimes works for Leukemia is called Car T-cell therapy . This is a treatment where scientist add a lab made gene to your cancer fighting T cells that help the T-cells detect the cancerous cells. However, sometimes in car T-All, the new T cells mistake each other for cancerous cells and kill each other, so that does not work.

With the new treatment that saved Alyssa, what the scientist did is something similar to CarT-cell therapy. They brought in newly modified T-cells, but with these donated T-cells they stripped them of certain receptors that would make them look foreign to the patients immune system. They also stripped these  T cells of  a protein called CD7, another protein called Cd52 that is targeted by certain cancer treatments , and finally they added a new receptor to the T-cells that allowed them to target the cancerous CD7 carrying T-cells.

In order to make these genetic modifications, the scientists used the CRISPR gene editing tool in a technique known as ‘base editing”  to swap out individual letters in the T-cells DNA code. This entire therapy became known as base-edited Car T-cell therapy, and Alyssa is the first ever patient to receive it.

Alyssa is now 6 months past her treatment, she has received a bone marrow transplant to restore the T cells she lost through the therapy, and is home recovering.

This connects to what we have learned in AP Bio as the way that these individual letters in the T-cells are able to be swapped out and replaced is all thanks to translation. Translation is the process by which proteins are made from information from mRNA. To start the initiation process of translation, a ribosome assembles around the mRNA. The start codon (typically AUG) is recognized by the tRNA molecule carrying its specific amino acid. During the next phase, elongation, the ribosome move along the mRNA, decoding each codon and adding corresponding amino acids to the growing peptide chain through peptide bonds. However, in order to get rid of or change amino acids like the scientists are doing with the T cells in base edited Car T-cell therapy, the scientists are most likely getting rid of some of the codons/letters which prevents these certain amino acids fro, being coded and forming proteins, or swapping out different codons to for different amino acids and, thus, different proteins and change the receptor protein on the T cell to make it attack the cancerous T cells.

The past two summers, I have worked at Sunrise Day Camp, a summer day camp for children with cancer and their siblings. Therefore, I have spent a lot of time and gotten very close with many kids and teenagers in a very similar situation to Alyssa, and was very curious into finding new advanced treatments these scientists are coming up with to help cure these cancers and save these kids. What else do you think scientist can come up with in the near future to help fight against cancer?

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