Yesterday, Monday
October 1, 2018, the New York times released an article reporting a cancer
treatment had go awry. The treatment used immunotherapy, a type of treatment
that boosts the body’s natural defenses. In this case, scientists genetically
alter a person’s white blood cells so that they are able to recognize cancer
cells. This type of immunotherapy was called CAR-T. CAR-T stands for the
anti-CD19 chimeric antigen receptor (CAR) T cell product, and it is the first
FDA-approved gene-modification cell therapy of any kind. It has had much
success in sending aggressive cancers into remission. However, in this
instance, when scientists genetically altered the T-cells of patient 116 they
accidentally altered one cancer cell’s (leukemia cell) genome as well. The
change made the leukemia cell invisible to the newly altered white blood cells.
Although the patient briefly entered remission, the leukemia cell began to rapidly
divide without detection causing a relapse and, eventually, the death of
patient 116. After his relapse, blood tests showed that every new leukemia cell
contained the genetic mutation.
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| Basics of immunotherapy |
This article,
showing what can go wrong with engineered genetic mutations, was coincidentally
published the same day the Nobel Prize for Medicine was announced. The 2018
winners, Dr. James Allison and Dr. Tasuku Honjo, were awarded the prize based
off of their research on/discovery of immunotherapy in cancer treatments. They
used different target antigens than the study mentioned above, however the
basis of the treatments is the same. The idea behind immunotherapy is portrayed
in the image below. Essentially, scientists are prompting T-cells to recognize
and destroy cancer cells that usually have defenses to evade such white blood
cells. This can either be done with drugs to block the cancer’s defense, or with
a transfection which allows the T-cell to produce the antigens they need
themselves. A transfection is when a group of cells is exposed to a virus that
contains DNA that is to be incorporated into the host’s genome so that they may
produce the desired proteins (antigens).
This article shows
the good and the evil of genetic modification. Patient 116 was the first of
over 400 patients to have this negative side effect of the treatment. Not all
of the other 400 patients were sent into permanent remission, but overall the treatment
had been more successful than negative. Patient 116 died as a direct result of
the engineered genetic mutation. This plays directly to the fears that the
public has on genetic mutation, whether it be immunotherapy or GMOs in foods.
People worry that scientists may create super bugs, or that GMOs are dangerous.
As scientists, we know that this is largely untrue and that there is generally
no danger in eating GMOs. However, when it is people’s own cells, there is
increased risk.
Genetic editing is
still an emerging science. Although there are risks, as exemplified above, it
is important to think about the long term, positive implications. Genetic
editing has the potential to cure diseases that previously would have been a
death sentence. Although patient 116 died from this treatment, there were over
400 other patients who experienced benefits. It is important that one failed
attempt does not take away from the successes and that we do not allow it to
impede research and scientific discovery.
Sources:
Good post on a very important topic. It is interesting that the headline of the NYT article emphasizes the one patient who died and not the 400 who benefitted. But it is important that scientists are candid about the risks of their science.
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