Genetic diseases can have devastating consequences for the people who inherit them. In recent years, scientists have discovered that there are human genetic diseases that are treatable and perhaps even curable through gene editing. Gene editing is the process of changing parts of a person’s DNA. Often compared to a word processor or a pencil and eraser, precision gene editing agents can alter parts of a person’s genome to correct “spelling mistakes,” or mutations in their DNA.
David Liu is a professor of natural sciences at Harvard University. He co-founded several biotechnology companies, including Prime Medicine, Beam Therapeutics, Editas Medicine, Chroma Medicine, Pairwise Plants, Exo Therapeutics, Resonance Medicine, and Nvelop Therapeutics. Liu and his team pioneered base edit and prime editing, two new innovative methods of gene editing that enable precise changes to a person’s genetic code.
In March, Liu spoke at the 2023 Imagine Solutions Conference in Naples, Florida, about how gene editing works, why it’s important, and the strides he and his team have made in the field so far.
What is gene editing and why are scientists interested in developing and using this tool?
gene editing is a technique that makes it possible to purposefully change genes in the DNA of various organisms, including crops And animals. Scientists are interested in developing and using genome editors because they are powerful tools for studying biology, treating human disease and improve agriculture. More than 50 clinical studies the use of gene editing to treat a variety of conditions is ongoing.
According to the US National Human Genome Research Instituteapproximately 280 million people worldwide live with a rare genetic disease. Most of these individuals have little to no treatment options, leaving them resigned to their genetic fate.
Can you explain the difference between basic and prime editing? Why would scientists use one over the other?
Neither basic editors nor first editors exist in nature; instead, both are lab-developed from natural and lab-developed components.
Basic editingoften compared to a pencil and eraser, can correct accurately and efficiently four of the most common types of spelling errors occurring in DNA, together account for about 30% of all known disease-causing DNA errors. Base editors perform a chemical reaction on an individual DNA letter or “base”, rearranging its atoms to become another DNA base instead. But basic editing cannot be used to correct errors such as extra letters, missing letters, or the other types of single-letter misspellings in DNA.
Unlike, first editors, sometimes compared to the “find and replace” function in a word processor, can replace any stretch of up to hundreds of DNA letters with virtually any other set of letters. In theory, the versatility of prime editing makes it possible to correct most of the known DNA misspellings that cause disease by restoring the typical DNA sequence.
Basic editing and primary editing each have their own strengths and weaknesses. Whether a scientist should use basic or prime editing depends on many factors, such as the specific sequence being edited, the unique sequence context, whether the edit will be made in an animal or patient, and the specific goals of the scientist.
How can gene editing treat diseases?
The words “bean” and “bone” differ only by one letter, yet they have completely different meanings. In a cellular context, a one-letter misspelling at a specific position in a person’s DNA — say, from a C to a T — can mean the difference between a healthy individual and an individual with progeria, a rare genetic disease that causes children to die quickly. aging. Basic editing has the potential to correct these small but critical DNA misspellings to reverse or cure diseases.
In a 2021 study which I conducted in collaboration with scientists at the National Institutes of Health and Vanderbilt University, we used basic editing to reverse progeria in mice and more than double their lifespan. In the same year, we used basic editing to convert a diseased form of the hemoglobin gene HBB to a benign variant treatment of sickle cell disease in mice.
Basic editing has also been successfully used in humans. After treatments of chemotherapy and a bone marrow transplant, it was not possible to treat the 13-year-old from Alyssa pediatric leukemia, she enrolled in one clinical trial directed by Waseem Qasim’s team at the University of College London. The base-edited T cells cleared Alyssa’s cancer and she remains in complete remission seven months later.
What are the implications of prime editing for the study and treatment of genetic diseases and human health?
Like basic editing, fine editing has enormous implications for the study and treatment of genetic diseases. Because of its unique ability to make virtually any localized change in DNA at a target sequence, prime editing has the potential to correct a much larger number of mutations known to cause genetic diseases than previously possible. However, before prime editors can be routinely used to treat genetic diseases, they must be tested for their safety and efficacy in patients, as well as their compatibility with different delivery platforms.
In addition, the therapeutic application of any genome-editing technology requires a clear understanding of the relationship between the genetic mutation and the resulting disease to ensure that the benefits outweigh the risks.
What recent or ongoing development in your field are you most excited about?
I am pleased that many laboratories, including my ownAre developing methods to exactly to install whole healthy genes to specific positions in the human genome. This could increase the potential therapeutic range of gene editing.
I’m excited about it too ongoing efforts to develop delivery technologies that can safely and efficiently deliver genome-editing agents into target cells in animals and human patients. Genome editing agents cannot easily enter cells due to their large size, unlike small molecule drugs such as ibuprofen and aspirin, which can easily enter cells due to their low molecular weight. As a result, scientists must use creative ways to deliver genome editors to their targets – a critical step if we hope to broaden the scope of therapeutic gene editing.
We have recently developed for this engineered virus-like particles, which are capable of delivering base editors and prime editors to specific tissues in living organisms. As the field continues to develop and improve delivery methods, the promise of therapeutic genome editing will continue to encompass more patient communities.
What ethical aspects of this technology have you and other researchers considered?
There are several ethical issues surrounding the technology researchers use in the field have consideredincluding the challenges of achieving fair access to genome editing technologies, the potential for more stigmatization of marginalized individuals and the potential for abuse. In cases where the technology is used with good intentions, such as treating disease and alleviating suffering, questions of accessibility of the patient become paramount.
No fundamental technology is inherently good or bad, and the ability to edit our genomes is no exception. I still hope that we collectively and thoughtfully choose to use these powerful technologies for the betterment of as many people as possible.