There is a new tool in the biotechnology tool belt that may revolutionize the way medicine treats a host of diseases. It is called CRISPR-Cas9. CRISPR uses a bacterial enzyme to precisely edit DNA, and scientists all over the world are using it to transform cells in hopes that one day these genetically-altered cells may cure disease.
Scientists in China are hoping CRISPR will successfully treat lung cancer, and they are launching a first-of-its-kind clinical trial in 10 patients who have exhausted other treatment options. Researchers have edited the patient’s own immune cells to attack lung cancer. Bloomberg has the details:
Western Sichuan University West China Hospital, has recruited the first patient for a ten-people clinical trial, which will activate immune cells using Crispr and infuse them back into patients to fight lung cancer. Due to potential risks in using the pioneering treatment for humans, the team has decided to treat the first group of three patients one at a time, Lu said in a phone interview.
Formally called Crispr-Cas9, the genetic editing tool acts like a pair of precise molecular scissors that can cut out unwanted sections of DNA and insert desired ones. The team is using it to remove a gene that encodes a protein named PD-1, which normally keeps the immune cells in check but is also used by cancer cells to hide from the immune system.
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The engineering is intended to switch on the immune response to attack cancer.
Of course, safety is a huge concern. Anytime you edit the DNA of a cell, there is a chance there will be “off-target” mutations. Researchers are also concerned that the modified immune cells will attack other tissues in the body, not just the cancer cells. The trial is taking it slow. They plan to treat one patient at a time for the first three patients to assess the safety of the procedure.
This is the kind of genetic engineering that we should be supporting: genetic modification in targeted cells that is for therapy only. This is what is called somatic gene therapy, which means the modification is medicinal in nature and is for just that patient and will not be passed onto any offspring.
In stark moral contrast are the experiments done earlier this year also by Chinese scientists that used CRISPR to modify the DNA of days-old embryos. The researchers were trying to re-engineer the gene that causes a blood disorder, so the intent was therapeutic. The problem lies in the stage of human development where the engineering was performed. Any genetic modifications done at the embryonic stage are considered germ-line modifications, meaning those genetic changes will be incorporated into reproductive cells and will be passed down from generation to generation.
There is also great risk involved in editing a human organism so early in development. Any “off-target” mutations maybe incorporated into the person’s whole body, not just in a few transplanted cells. There is also the reality that many embryos perish during the procedure. In the Chinese experiments, 15 embryos out of 86 total did not survive.
Of those that survived, 54 were tested to see if the genetic engineering worked. Only four embryos showed evidence of the intended modification.
Overall, there was evidence of what The New York Times called “collateral damage,” meaning unintended mutations in other parts of the genome caused by the attempted genetic engineering. The Times reported, “The Chinese researchers point out that in their experiment gene editing almost certainly caused more extensive damage than they documented.”
Prominent researchers have called for a voluntary moratorium on using CRISPR technology in human embryos, even for therapeutic purposes, because of the inherent risk to multiple generations. They rightly argue that gene editing in humans should only be attempted in therapeutic cases where any modifications cannot be passed on.
It is critical that we understand the difference between the genetic engineering of adult patients and that of embryos. CRISPR holds great promise to cure disease, but it is imperative we use it in such a way that the genetic integrity of future generations is safeguarded.