Tagged: gene editing

  • Competition is intensifying among scientists to develop and use gene editing and immunotherapy to defeat intractable diseases
  • Chinese scientists were the first to inject people with cells modified by the CRISPR–Cas9 gene-editing technique
  • Several studies have extracted a patient’s own immune cells, modified them using gene-editing techniques, and re-infused them into the patient to seek and destroy cancer cells
  • A new prêt à l'emploi gene editing treatment disables the gene that causes donor immune cells to attack their host
  • The technique harvests immune cells from a donor, modifies and multiplies them so that they may be used quickly, easily and cheaply on different patients
  • Commercial, technical, regulatory and ethical barriers to gene editing differ in different geographies 

Gene editing battles

Gene editing and immunotherapy are developing at a pace. They have been innovative and effective in the fight against melanoma, lung cancer, lymphomas and some leukaemias, and promise much more. Somatic gene therapy changes, fixes and replaces genes at the tissue or cellular levels to treat a patient, and the changes are not passed on to the patient’s offspring. Germ line gene therapy inserts genes into reproductive cells and embryos to correct genetic defects that could be passed on to future generations.  Although there are still many unanswered clinical, commercial and ethical questions surrounding gene therapy, its future is assured and will be shaped by unexpected new market entrants and competition between Chinese and Western scientists, which is gaining momentum.
14 February 2017

On the 14th February 2017 an influential US science advisory group formed by the National Academy of Sciences and the National Academy of Medicine gave support to the modification of human embryos to prevent “serious diseases and disabilities” in cases where there are no other “reasonable alternatives”. This is one step closer to making the once unthinkable heritable changes in the human genome. The Report, however, insisted that before humanity intervenes in its own evolution, there should be a wide-ranging public debate, since the technology is associated with a number of unresolved ethical challenges. The French oppose gene editing, the Dutch and the Swedes support it, and a recent Nature editorial suggested that the EU is, “habitually paralysed whenever genetic modification is discussed”. In the meantime, clinical studies, which involve gene-editing are advancing at a pace in China, while the rest of the world appears to be embroiled in intellectual property and ethical debates, and playing catch-up.
15 February 2017

On the 15th February 2017, after a long, high-profile, heated and costly intellectual property action, judges at the US Patent and Trademark Office ruled in favor of Professor Feng Zhang and the Broad Institute of MIT and Harvard, over patents issued to them associated with the ownership of the gene-editing technology CRISPR-Cas9: a cheap and easy-to-use, all-purpose gene-editing tool, with huge therapeutic and commercial potential.
The proceedings were brought by University College Berkeley who claimed that the CRISPR technology had been invented by Professor Jennifer Doudna of the University, and Professor Emmanuelle Charpentier, now at the Max Planck Institute for Infection Biology in Berlin, and described in a paper they published in the journal Science in 2012. Berkeley argued that after the 2012 publication, an “obvious” development of the technology was to edit eukaryotic cells, which Berkeley claimed is all that Zhang did, and therefore his patents are without merit.

The Broad Institute countered, suggesting that Zhang made a significant inventive leap in applying CRISPR knowledge to edit complex organisms such as human cells, that there was no overlap with the University of California’s research outcomes, and that the patents were therefore deserved. The judges agreed, and ruled that the 10 CRISPR-Cas9 patents awarded to Zhang and the Broad Institute are sufficiently different from patents applied for by Berkeley, so that they can stand. 
The scientific community

Interestingly, before the 15th February 2017 ruling, the scientific community had appeared to side with Berkeley. In 2015 Doudna, and Charpentier were awarded US$3m and US$0.5m respectively for the prestigious Breakthrough Prize in life sciences and the Gruber Genetics Prize. In 2017 they were awarded the Japan Prize of US$0.45m for, “extending the boundaries of life sciences”. Doudna and Charpentier have each founded companies to commercially exploit their discovery: respectively Intellia Therapeutic, and CRISPR Therapeutics.
16 February 2017

A day after the patent ruling, Doudna said: “The Broad Institute is happy that their patent didn’t get thrown out, but we are pleased that our patent based on earlier work can now proceed to be issued”. According to Doudna, her patents are applicable to all cells, whereas Zhang’s patents are much more narrowly indicated. “They (Zhang and the Broad Institute) will have patents on green tennis balls. We will get patents on all tennis balls,” says Doudna.
Gene biology

Gene therapy has evolved from the science of genetics, which is an understanding of how heredity works. According to scientists life begins in a cell that is the basic building block of all multicellular organisms, which are made up of trillions of cells, each performing a specific function. Pairs of chromosomes comprising a single molecule of DNA reside in a cell’s nucleus. These contain the blueprint of life: genes, which determine inherited characteristics. Each gene has millions of sequences organised into segments of the chromosome and DNA. These contain hereditary information, which determine an organism’s growth and characteristics, and genes produce proteins that are responsible for most of the body’s chemical functions and biological reactions.

Roger Kornberg, an American structural biologist who won the 2006 Nobel Prize in Chemistry "for his studies of the molecular basis of eukaryotic transcription", describes the Impact of human genome determination on pharmaceuticals:
China’s first
While American scientists were fighting over intellectual property associated with CRISPR-Cas9, and American national scientific and medical academies were making lukewarm pronouncements about gene editing, Chinese scientists  had edited the genomes of human embryos in an attempt to modify the gene responsible for β-thalassemia and HIV, and are planning further clinical studies. In October 2016, Nature reported that a team of scientists, led by oncologist Lu You, at Ghengdu’s Sichuan University in China established a world first by using CRISPR-Cas9 technology to genetically modify a human patient’s immune cells, and re-infused them into the patient with aggressive lung cancer, with the expectation that the edited cells would seek, attack and destroy the cancer. Lu is recruiting more lung cancer patients to treat in this way, and he is planning further clinical studies that use similar ex vivo CRISPR-Cas9 approaches to treat bladder, kidney and prostate cancers
The Parker Institute for Cancer Immunotherapy
Conscious of the Chinese scientists’ achievements, Carl June, Professor of Pathology and Laboratory Medicine at the University of Pennsylvania and director of the new Parker Institute for Cancer Immunotherapy, believes America has the scientific infrastructure and support to accelerate gene editing and immunotherapies. Gene editing was first used therapeutically in humans at the University of Pennsylvania in 2014, when scientists modified the CCR5 gene (a co-receptor for HIV entry) on T-cells, which were injected in patients with AIDS to tackle HIV replication. Twelve patients with chronic HIV infection received autologous cells carrying a modified CCR5 gene, and HIV DNA levels were decreased in most patients.
Medical science and the music industry

The Parker Institute was founded in 2016 with a US$250m donation from Sean Parker, founder of Napster, an online music site, and former chairman of Facebook. This represents the largest single contribution ever made to the field of immunotherapy. The Institute unites 6 American medical schools and cancer centres with the aim of accelerating cures for cancer through immunotherapy approaches. 

Parker, who is 37, believes that medical research could learn from the music industry, which has been transformed by music sharing services such as Spotify. According to Parker, more scientists sharing intellectual property might transform immunotherapy research. He also suggests that T-cells, which have had significant success as a treatment for leukaemia, are similar to computers because they can be re-programed to become more effective at fighting certain cancers. The studies proposed by June and colleagues focus on removing T-cells, from a patient’s blood, modifying them in a laboratory to express chemeric antigen receptors that will attack cancer cells, and then re-infusing them into the patient to destroy cancer. This approach, however, is expensive, and in very young children it is not always possible to extract enough immune cells for the technique to work.

Prêt à l'emploi therapy

Waseem Qasim, Professor of Cell & Gene Therapy at University College London and Consultant in Paediatric immunology at Great Ormond Street Hospital, has overcome some of the challenges raised by June and his research. In 2015 Qasim and his team successfully used a prêt à l'emploi gene editing technique on a very young leukaemia patient. The technique, developed by the Paris-based pharmaceutical company Cellectis, disables the gene that causes donor-immune cells to attack their host. This was a world-first to treat leukaemia with genetically engineered immune cells from another person. Today, the young leukaemia patient is in remission. A second child, treated similarly by Qasim in December 2015, also shows no signs of the leukaemia returning. The cases were reported in 2017 in the journal Science Translational Medicine.
Universal cells to treat anyone cost effectively

The principal attraction of the prêt à l'emploi gene editing technique is that it can be used to create batches of cells to treat anyone. Blood is collected from a donor, and then turned into “hundreds” of doses that can then be stored frozen. At a later point in time the modified cells can be taken out of storage, and easily re-infused into different patients to become exemplars of a new generation of “living drugs” that seek and destroy specific cancer cells. The cost to manufacture a batch of prêt à l'emploi cells is estimated to be about US$4,000 compared to some US$50,000 using the more conventional method of altering a patient’s cells and returning them to the same patient. Qasim’s clinical successes raise the possibility of relatively cheap cellular therapy using supplies of universal cells that could be dripped into patients' veins on a moment’s notice.
CRISPR-Cas9 provides a relatively cheap and easy-to-use means to get an all-purpose gene-editing technology into clinics throughout the world. Clinical studies using the technology have shown a lot of promise especially in blood cancers. These studies are accelerating, and prêt à l'emploi gene editing techniques as an immunotherapy suggest a new and efficacious therapeutic pathway. Notwithstanding the clinical successes, there remain significant clinical, commercial and ethical challenges, but expect these to be approached differently in different parts of the world. And expect these differences to impact on the outcome of the scientific race, which is gaining momentum.
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  • Chinese scientists lead the world in editing genomes of human embryos in order to develop new therapies for intractable diseases
  • US and UK regulators have given permission to edit the genes of human embryos
  • CRISPR-Cas9 has become the most common gene editing platform, which acts like is a pair of molecular scissors
  • CRISPR technology has the potential to revolutionize medicine, but critics say it could create a two-tiered society with elite citizens, and an underclass and have called for a worldwide moratorium on gene editing
  • Roger Kornberg, professor of medicine at Stanford University and 2006 Nobel Prize winner for Chemistry explains the science, which underpins gene-editing technology
Gene editing positioned to revolutionise medicine
It is a world first for China.
In 2015, a group of Chinese scientists edited the genomes of human embryos in an attempt to modify the gene responsible for β-thalassemia, a potentially fatal blood disorder. Researchers, led by Junjiu Huang from Sun Yat-sen University in Guangzhou, published their findings in the journal Protein & Cell.
In April 2016, another team of Chinese scientists reported a second experiment, which used the same gene editing procedure to alter a gene associated with resistance to the HIV virus. The research, led by Yong Fan, from Guangzhou Medical University, was published in the Journal of Assisted Reproduction and Genetics. At least two other groups in China are pursuing gene-editing research in human embryos, and thousands of scientists throughout the world are increasingly using a gene-editing technique called CRISPR-Cas9.


Almost all cells in any living organism contain DNA, a type of molecule, which is passed on from one generation to the next. The genome is the entire sequence of DNA or an organism. Gene editing is the deliberate alteration of a selected DNA sequence in a living cell. CRISPR-Cas9 is a cheap and powerful technology that makes it possible to precisely “cut and paste” DNA, and has become the most common tool to create genetically modified organisms. Using CRISPR-Cas9, scientists can target specific sections of DNA, delete them, and if necessary, insert new genetic sequences. In its most basic form, CRISPR-Cas9 consists of a small piece of RNA, a genetic molecule closely related to DNA, and an enzyme protein called Cas9. The CRISPR component is the programmable molecular machinery that aligns the gene-editing tool at exactly the correct position on the DNA molecule. Then Cas9, a bacterial enzyme, cuts through the strands of DNA like a pair of molecular scissors. Gene editing differs from gene therapy, which is the introduction of normal genes into cells in place of missing or defective ones in order to correct genetic disorders.
Ground-breaking discovery 

The ground-breaking discovery of how CRISPR-Cas9 could be used in genome editing was first described by Jennifer Doudna, Professor of Chemistry and Cell Biology at the University of California, Berkeley, and Emmanuelle Charpentier, a geneticist and microbiologist, now at the Max Plank Institute for Infections in Berlin, and published in the journal Science in 2012.

In 2011 Feng Zhang, a bioengineer at the Broad Institute, MIT and Harvard, learned about CRISPR and began to work adapting CRISPR for use in human cells. His findings were published in 2013, and demonstrated how CRISPR-Cas9 can be used to edit the human genome in living cells.  

Subsequently, there has been a battle, which is on-going, between the scientists and their respective institution over the actual discovery of CRISPR’s use in human embryos, and who is entitled to the technology’s patents.
Gene editing research gathers pace worldwide: a few western examples

In 2016 a US federal biosafety and ethics panel licensed scientists at the University of Pennsylvania’s new Parker Institute of Cancer Immunotherapy to undertake the first human study to endow T-cells with the ability to attack specific cancers. Patients in the study will become the first people in the world to be treated with T-cells that have been genetically modified.

T-cells are designed to fight disease, but puzzlingly they are almost useless at fighting cancer. Carl June, the Parker Institute’s director and his team of researchers, will alter three genes in the T-cells of 18 cancer patients, essentially transforming the cells into super fighters. The patients will then be re-infused with the cancer-fighting T-cells to see if they will seek and destroy cancerous tumors.

Also in 2016, the UK’s Human Fertilisation and Embryology Authority (HFEA), which regulates fertility clinics and research, granted permission to a team of scientists led by Kathy Niakan at the Francis Crick Institute in London to edit the genes of human IVF embryos in order to investigate the causes of miscarriage. Out of every 100 fertilized eggs, fewer than 50 reach the early blastocyst stage, 25 implant into the womb, and only 13 develop beyond three months.
Frederick Lander, a development biologist at the Karolinska Institute Stockholm, is also using gene editing in an endeavour to discover new ways to treat infertility and prevent miscarriages. Lander is the first researcher to modify the DNA of healthy human embryos in order to learn more about how the genes regulate early embryonic development. Lander, like other scientists using gene-editing techniques on human embryos, is meticulous in not allowing them to result in a live birth. Lander only studies the modified embryos for the first seven days of their growth, and he never lets them develop past 14 days. “The potential benefits could be enormous”, he says.
Gene editing cures in a single treatment

Doctors at IVF clinics can already test embryos for genetic diseases, and pick the healthiest ones to implant into women. An advantage of gene editing is that potentially it could be used to correct genetic faults in embryos instead of picking those that happen to be healthy. This is why the two Chinese research papers represent a significant turning point. The gene editing technology they used has the potential to revolutionize the whole fight against devastating diseases, and to do many other things besides. The main benefit of gene editing therapy is that it provides potential cures for intractable diseases with a single treatment, rather than multiple treatments with possible side-effects.

The promise of gene editing for fatal and debilitating diseases
Among other things, gene editing holds out promise for people with fatal or debilitating inherited diseases. There are over 4,000 known inherited single gene conditions, affecting about 1% of births worldwide. These include the following:- cystic fibrosis, which each year affects about 70,000 people worldwide, 30,000 in the US, and about 10,000 in the UK; Tay-Sachs disease, which results in spasticity and death in childhood. The BRCA1 and BRCA2 inherited genes predispose women with a significantly greater chance of developing breast or ovarian cancer. Sickle-cell anaemia, in which inheriting the sickle cell gene from both parents causes the red blood cells to spontaneously “sickle” during a stress crisis; heart disease, of which many types are passed on genetically; haemophilia, a bleeding disorder caused by the absence of genetic clotting agent and. Huntington disease, a genetic condition which slowly kills victims by affecting cognitive functions and neurological status. Further, genomics play a significant role in mortality from chronic conditions such as cancer, diabetes and heart disease.
A world first

Huang and his colleagues set out to see if they could replace a gene in a single-cell fertilized human embryo. In principle, all cells produced as the embryo develops would then have the replaced gene. The embryos used by Huang were obtained from fertility clinics, but had an extra set of chromosomes, which prevented them from resulting in a live birth, though they did undergo the first stages of development. The technique used by Huang’s team involved injecting embryos with the enzyme complex CRISPR-Cas9, which, as described above, acts like is a pair of molecular scissors that can be designed to find and remove a specific strand of DNA inside a cell, and then replace it with a new piece of genetic material.
The science underpinning gene editing

In the two videos below Roger Kornberg, professor of medicine at Stanford University and 2006 Nobel Prize winner for Chemistry for his work on “transcription”, the process by which DNA is converted into RNA, explains the science, which underpins gene-editing technology:
How biological information, encoded in the genome, is accessed for all human activity

Impact of human genome determination on pharmaceuticals
An immature technology
Huang’s team injected 86 embryos, and then waited 48 hours; enough time for the CRISPR-Cas9 system, and the molecules that replace the missing DNA to act, and for the embryos to grow to about eight cells each. Of the 71 embryos that survived, 54 were genetically tested. Only 28 were successfully spliced, and only a fraction of those contained the replacement genetic material.
Therapy to cure HIV
Fan, the Chinese scientist who used CRISPR in an endeavor to discover a therapy for HIV/Aids, collected 213 fertilized human eggs, donated by 87 patients, which like embryos used by Huang, were unsuitable for implantation, as part of in vitro fertility therapy. Fan used CRISPR–Cas9 to introduce into some of the embryos a mutation that cripples an immune-cell gene called CCR5. Some humans who naturally carry this mutation are resistant to HIV, because the mutation alters the CCR5 protein in a way that prevents the virus from entering the T-cells it tries to infect. Fan’s analysis showed that only 4 of the 26 human embryos targeted were successfully modified.
Deleting and altering genes not targeted
In 2012, soon after scientists reported that CRISPR could edit DNA, experts raised concerns about “off-target effects,” where CRISPR inadvertently deletes or alters genes not targeted by the scientists. This can happen because one molecule in CRISPR acts like a bloodhound, and sniffs around the genome until it finds a match to its own specific sequence. Unfortunately, the human genome has billions of potential matches, which raises the possibility that the procedure might result in more than one match. 
Huang is considering ways to decrease the number of “off-target” mutations by tweaking the enzymes to guide them more precisely to a desired spot, introducing the enzymes in a different format in order to try to regulate their lifespans, allowing enzymes to be shut down before mutations accumulate; and varying the concentrations of the introduced enzymes and repair molecules. He is also, considering using other gene-editing techniques, such as LATENT.

The slippery slope to eugenics

Despite the potential therapeutic benefits from gene editing, critics suggest that genetic changes to embryos, known as germline modifications, are the start of a “slippery slope” that could eventually lead to the creation of a two-tiered society, with elite citizens, genetically engineered to be smarter, healthier and to live longer, and an underclass of biologically run-of-the-mill humans.
Some people believe that the work of Huang, Fan and others crosses a significant ethical line: because germline modifications are heritable, they therefore could have an unpredictable effect on future generations. Few people would argue against using CRISPR to treat terminal cancer patients, but what about treating chronic diseases or disabilities? If cystic fibrosis can be corrected with CRISPR, should obesity, which is associated with many life-threatening conditions? Who decides where the line is drawn?
40 countries have banned CRISPR in human embryos. Two prominent journals, Nature and Science, rejected Huang’s 2012 research paper on ethical grounds, and subsequently, Nature published a note calling for a global moratorium on the genetic modification of human embryos, suggesting that there are “grave concerns” about the ethics and safety of the technology.
A 2016 report from the Nuffield Council on Bioethics suggests that because of the steep rise in genetic technology, and the general availability of cheap, simple-to-use gene-editing kits, which make it relatively straightforward for enthusiasts outside laboratories to perform experiments, there needs to be internationally agreed ethical codes before the technology develops further.
Recently, the novelist Kazuo Ishiguro, among others, joined the debate, arguing that social changes unleashed by gene editing technologies could undermine core human values. “We’re coming close to the point where we can, objectively in some sense, create people who are superior to others,” says Ishiguro.

CRISPR has been described as the “Model T of genetics”.  Just as the Model T was the first motor vehicle to be successfully mass-produced, and made driving cheap and accessible to the masses, so CRISPR has made a complex process to alter any piece of DNA in any species easy, cheap and reliable, and accessible to scientists throughout the world. Although CRISPR still faces some technical challenges, and notwithstanding that it has ignited significant protests on ethical grounds, there is now a global race to push the boundaries of its capabilities well beyond its present limits.
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