The creator of the gene edited babies He Jiankui was released from a Chinese prison recently. His research posed the grave concern of bioethics and lapse of supervision. Gene therapy was thought by many as a breakthrough in human medical history, while others believed it opened the Pandora’s box.
The Tragic Death of an 18-Year-Old
Jesse Gelsinger, 18, had a rare metabolic disorder called ornithine transcarbamylase deficiency syndrome, or OTCD, in which ammonia builds up to lethal levels in the blood. He managed the condition with a low-protein diet and a regimen of nearly 50 pills a day.
In 1999, the kind-hearted Jesse volunteered to participate in a gene therapy trial with the hope to help others with the same disease. However, a few days later, he became the first person to die as a result of a gene therapy experiment.
The potential OTCD treatment was to inject a genetically modified and weakened adenovirus vector into the patient’s liver, and to introduce the normal ornithine aminomethyltransferase gene (OTC gene) into the patient’s liver chromosomal DNA, to restore the liver’s ability to metabolize ammonia.
Jesse received this modified virus.
However, he had an intense inflammatory response and developed a dangerous blood-clotting disorder, followed by kidney, liver, and lung failure. Four days after receiving the shot Jesse was declared brain dead.
Jesse’s family sued the University of Pennsylvania that developed the program.
The tragedy shocked the drug development community, and immediately cooled the research boom in gene therapy. The entire gene therapy industry began to crumble: investors withdrew their funds, startups went bankrupt, the heads of R&D projects were stripped of all their titles, and gene therapy centers were shut down.
The story Jesse is well known in the field of gene therapy. The tragedy brought gene therapy development to a near standstill for the next 18 years. Mainly because Jesse’s accidental death made many developers believe that there are many unknown and uncontrollable serious risk factors in gene therapy, as if shooting in the darkness where the target cannot be seen.
More Deaths Caused by Gene Therapy
After the death of Jesse, 18 years later, a gene therapy for an eye illness was approved by the FDA in 2017, Spark Therapeutics’ Luxturna, a treatment to a rare genetic retinal disease. It’s specifically approved for people who have a mutated RPE65 gene: Luxturna uses a modified virus to deliver a healthy copy of the gene directly to a patient’s retinal cells through eye surgery. It only required local injection, and had little effect on the body. That’s one of the reasons it could succeed on the market. It indeed gave a spark to the field of gene therapy.
Safety issues once again emerged after two successful stories.
In 2019, in an animal trial of a gene therapy developed by Solid for the treatment of Duchenne muscular dystrophy, three monkeys and three piglets all suffered severe toxicity and eventually died. The accident led to the direct halt of the development of the therapy.
Less than a year later, Astellas Pharma acknowledged that a fourth boy died in the troubled Phase I/II trial through which its Astellas Gene Therapies (formerly Audentes Therapeutics) has been evaluating its adeno-associated virus (AAV) gene therapy candidate AT132 in patients with muscular disease, X-linked Myotubular Myopathy (XLMTM).
This series of successive death cases of gene therapy undoubtedly cooled down the approach of gene therapy.
The disastrous gene therapy calls for a basic understanding of genes, the target of the gene therapy.
What is a Gene?
Genes (DNA) are the most delicate and complex structures in the human body. It exists in the nucleus of the human body’s cells to ensure the normal functioning of the structure and function of the human body; in addition, genes also determine characteristics such as height, gender, appearance, hair color, skin color, blood type, sex, etc
Scientists have now found that humans have at least about 20,000 to 23,000 genes. If the DNA in the 50 trillion cells of the human body is stretched and connected together, its length is equivalent to 16 times the distance from the earth to the sun. How can such a small nucleus fit such a length? Thus, the DNA twists further on top of the double helix, becoming supercoiled, like an old-fashioned telephone wire when twisted.
The outside of DNA is coated with proteins to form chromosomes. There are 23 pairs of chromosomes in each somatic cell of a normal person, and a chromosome contains hundreds to thousands of genes, that is, each chromosome is a highly coiled and compressed shape of genes.
The discovery of DNA is also the most important and well-known scientific story of the 20th century. In 1953, American biochemist James Dewey Watson and British physicist Francis Crick published in the journal Nature that they discovered the DNA of two strands of nucleotides, paired as a double helix form, encodes the genetic information of all living things.
Since then, genetic testing technology has flourished, ushering in a new era in biomedicine. For example, the PCR nucleic acid test we used in the Covid epidemic is a genetic test.
But at the same time, people are also wondering why the discovery of genes is obviously a good thing, but the gene therapy that followed has such a bumpy fate, causing many disasters, such as adverse reactions and even death.
Gene Therapy: A Pandora’s Box
The concept of gene therapy is very attractive: the target gene is introduced into the human body, to correct the incorrect gene and cure the disease. However, the structure of genes is not as simple as that of proteins. It is a very central and important substance in the nucleus. This kind of treatment targets the bad gene that needs to be corrected—however, it will damage the normal gene when it is off the target.
The consequence of serious off-targets, several cases of death, is a warning to the people.
The human genetic sequence is very important. It is the core and most critical thing of human nature. It cannot be changed casually. Genes control all of the individual organisms, and all important physiological processes such as protein synthesis, cell division, reproduction, etc., in life are also related to genes. Genes can reproduce themselves precisely and faithfully, ensuring the stability of life characteristics. Each country treats the human genetic information of its citizens as seriously as it treats a biological resource and information database, and even sets up special systems to protect it.
Therefore, some things in the human body are like a powerhouse that cannot be changed.
The 2020 Nobel Prize in Chemistry has been awarded to two scientists for their contributions to the discovery of a gene editing method called CRISPR-Cas9. This is a technique that allows precise modification of nucleotide fragments and has been described as “God’s scalpel.” However, this “God’s scalpel” cannot be used casually.
Chinese scientist He Jiankui tried to use gene editing technology to open “Pandora’s Box,” causing an uproar in the scientific community around the world. At that time, He Jiankui rashly edited the baby’s genes in the name of helping the offspring of AIDS patients. His unethical and immoral acts got him into imprisonment and cost him his career.
Therefore, when biotechnology is advancing by leaps and bounds, we need to be rational rather than blindly advancing. While we all want a better life, we need to be more cautious when it comes to the development of certain technologies that touch the microscopic level of matter in the human body.