Author

HealthPad

Details

Likes: 0
Items: 7
Directory: Cancer
Created: 1 year, 9 months ago

Share Cluster

Gene therapies

by HealthPad

5 years, 4 months ago

44566
0
Facebook

Twitter

Google+

LinkedIn

Report

For better or worse we all now live in CRISPR’s world

HealthPad

Directory:

Medical Technology

Tags:

Prime editing devised by researchers at the Broad Institute led by David Liu is a significant advance of the original CRISPR gene editing tool discovered in 2012
CRISPR can cut and edit your DNA to correct defects inside your body’s cells to prevent and heal a range of incurable diseases and has revolutionized biomedicine
The original CRISPR is fraught with inaccuracies referred to as off target effects
Prime editing substantially reduces CRISPR’s off target effects and has the potential to correct up to 89% of known disease-causing genetic variations
CRISPR also has the capacity to edit genes in an embryo in such a way that the change is heritable
In 2018 Chinese researcher He Jiankui “created” the world’s first CRISPR babies
This triggered international criticism from scientists and bioethicists
A principal concern is that CRISPR is easy-to-use, cheap, regularly used in thousands of laboratories throughout the world and there is no internationally agreed and enforceable regulatory framework for its use

For better or worse we all now live in CRISPR’s world

In 2012 the world of biomedicine changed when a revolutionary gene editing technology known as CRISPR-Cas9 (an acronym for Clustered Regularly Interspaced Short Palindromic Repeats) was discovered. The technology harnesses your body’s naturally occurring immune system that bacteria use to fight-off viruses and has the potential to forever change the fundamental nature of humanity. Since its discovery CRISPR has been developing at lightning speed primarily because it is simple and affordable and today is used in thousands of laboratories throughout the world.

In this Commentary

In this Commentary we describe prime editing, which is the latest advance of the CRISPR's tool box, devised bya team of researchers, led by Andrew Anzalone, a Jane Coffin Childs postdoctoral fellow from the Broad Institute of MIT and Harvard and published in the October 2019 edition of Nature. Prime editing is significant because it provides a means to eliminate the unintentional consequences of CRISPR and therefore bring the technique closer for use in clinics. But this is still a long way off.

We also review a case where an ambitious scientist “created” the first CRISPR babies. This immediately triggered international criticism and a call for tighter regulatory control of the technology. Scientists and bioethicists are concerned that CRISPR can easily be used to create heritable DNA changes, which ultimately could lead to ‘designer babies’.

These two accounts of CRISPR might seem “opposites” and not sit well together in a single Commentary. Notwithstanding, what prompted putting them together was John Travis, the News Managing Editor of the well-known scientific journal Science, who soon after CRISPR’s discovery in 2012 said, “For better or worse we all now live in CRISPR’s world”.

CRISPR and your DNA

CRISPR is different to traditional gene therapy, which uses viruses to insert new genes into cells to try and treat diseases and has caused some safety challenges. CRISPR, which avoids the use of viruses, was conceived in 2007 when a yogurt company identified an unexpected defence mechanism that its bacteria used to fight off viruses. Subsequent research made a surprising observation that bacteria could remember viruses. CRISPR has been likened to a pair of microscopic scissors that can cut and edit your DNA to correct defects inside your body’s cells to prevent and heal a range of intractable diseases. The standard picture of DNA is a double helix, which looks similar to a ladder that has been twisted. The steps in this twisted ladder are DNA base pairs. The fundamental building blocks of DNA are the four bases adenine (A), cytosine (C), guanine (G) and thymine (T). They are commonly known by their respective letters, A, C, G and T. Three billion of these letters form the complete manual for building and maintaining your body, but tiny errors can cause disease. For example, a mutation that turned one specific A into a T results in the most common form of sickle cell disease.

The original CRISPR

The original CRISPR tool, which is the first and most popular gene editing system, uses a guide RNA (principally a messenger carrying instructions from your DNA for controlling the synthesis of proteins) to locate a mutated gene plus an enzyme, like Cas9, to cut the double-stranded gene helix and create space for functioning genes to be inserted. However, a concern about CRISPR is that the editing could go awry and cause unintended changes in DNA that could trigger health problems. Findings of a study published in the July 2018 edition of the journal Nature Biotechnology found that such inaccuracies, referred to as off-target effects, were substantially higher than originally reported and some were thought to silence genes that should be active and activate genes that should be silent. These off-target effects, such as random insertions, deletions, translocations, or other base-to-base conversions, pose significant challenges for developing policy associated with the technology.

Subsequently however, the paper was retracted, and an error correction was posted on a scientific website. Contrary to their original findings, the authors of the Nature Biotechnology paper restated that the CRISPR-Cas9 gene editing approach, "can precisely edit the genome at the organismal level and may not introduce numerous, unintended, off-target mutations".

Base editing

Notwithstanding, researchers remained concerned about CRISPR’s off target effects and several devised a technique, referred to as base editing, to reduce these. Base editing is described in three research papers published in 2017: one in the November edition of the journal ‘Protein and Cell’, another in the October edition of ‘Science’ the and a third by researchers from the Broad Institute, in the October edition of the journal ‘Nature’. Base editing takes the original CRISPR-Cas9 and fuses it to proteins that can make four precise DNA changes: it can change the letters C-to-T, T-to-C, A-to-G and G-to-A. The technique genetically transforms base pairs at a target position in the genome of living cells with more than 50% efficiency and virtually no detectable off-target effects. Despite its success, there remained other types of point mutations that scientists wanted to target for diseases.

Prime editing

Prime editing is different to previous gene editing systems in that it uses RNA to direct the insertion of new DNA sequences in human cells. According to David Liu, the senior author of the 2019 Nature paper and a world renowned authority on genetics and next-generation therapeutics, “a major aspiration in the molecular life sciences is the ability to precisely make any change to the genome in any location. We think prime editing brings us closer to that goal”. Because prime editing provides a means to be more precise and more efficient in editing human cells in a versatile way, which eliminates many of CRISPR’s unintentional errors, it significantly expands the scope of gene editing for biological and therapeutic research.

You might also like:

CRISPR-Cas9 genome editing a 2-edged sword

Gene editing positioned to revolutionise medicine

There are around 75,000 different mutations that can cause disease in people and prime editing has the potential to correct up to 89% of known disease-causing genetic variations. According to Liu, "Prime editing is the beginning, rather than the end, of a long-standing aspiration in the molecular life-sciences to be able to make any DNA change in any position of a living cell or organism, including potentially human patients with genetic diseases". Liu’s team at the Broad Institute intends to continue optimizing prime editing. In their October 2019 Nature paper researchers reported that they can precisely correct mutant genes, which cause sickle cell anaemia and Tay Sachs disease.

Sickle cell anaemia and Tay Sachs

Sickle cell anaemia is an inherited form of anaemia. This is when there are not enough healthy red blood cells (haemoglobin) to carry adequate oxygen throughout your body. The condition is the most common inherited blood disorder in the US, affecting 70,000 to 80,000 and further it is estimated each year some 300,000 babies are born with the disorder worldwide. Tay-Sachs disease is a rare and fatal nerve condition often caused by the addition of four extra letters of code. Although anyone can be a carrier of the disease it is much more common among people of Ashkenazi (Eastern European) Jewish descent. In the Ashkenazi Jewish population, the disease incidence is about 1 in every 3,500 new-borns and the carrier frequency is 1 in every 29 individuals.

Some moral and ethical implications of CRISPR

Being able to modify your DNA with CRISPR tools has transformed scientific research and is revolutionising medicine although it will be some time before the technology is regularly used in clinics. In addition to its potential benefits there are significant moral and ethical challenges associated with the technology, especially when it is used for germline engineering, which is the process by which your genome is edited in such a way that the change is heritable. Inappropriate use of germline editing could dent the progress of the CRISPR technology.

The first CRISPR babies

One well publicized inappropriate use of CRISPR is a team in China, led by He Jiankui of the Southern University of Science and Technology in Shenzhen, which in November 2018 “created” the first gene edited twins, known by their pseudonyms Lulu and Nana. He edited the twins’ cells to be immune to HIV infection when they were embryos, therefore ensuring that every cell in their bodies were changed, including their reproductive ones, which means their edited genomes can be passed on to their children and grandchildren, despite the fact that scientists cannot be sure what the long term effects of such lasting modifications might be. The twins are the first CRISPR babies and the first humans to have every cell in their body genetically modified using the technology.

In 2015 Chinese researchers were the first to edit the genes of a human embryo in a laboratory dish. Although the embryos did not go to term, the experiment triggered an international outcry from bioethicists, who argued that CRISPR should not be used to make babies. Notwithstanding, He Jiankui did just this.

He employed CRISPR to alter a gene in IVF embryos to disable the production of an immune cell surface protein, CCR5, which HIV uses to establish an infection before insemination. CCR5 is a well-studied genetic mutation, and there is scientific and medical value in understanding how CRISPR can be used to disable and prevent HIV/AIDS. He believed that the use of CRISPR technology was medically appropriate and expected his experiment, “to produce an IVF baby naturally immunized against AIDS”. But more contentiously, He created twins who could pass the protective mutation to future generations. It is CRISPR’s ability to easily and cheaply edit human embryos, eggs, or sperm in order to create irrevocable changes and the potential for designer babies, which raises concerns.

He defended his work at a Hong Kong genomics conference in late November 2018, but there was immediate and significant international criticism about the scientific and ethical legitimacy of his experiments, which broached China’s guidelines as well as international ethical and regulatory norms. A Chinese government investigation found He to have violated state law in pursuit of “personal fame and fortune”. His endeavours cost him his university position and the leadership of a biotech company he founded, which had successfully raised US$43m start-up capital and was advised by Craig Mello, professor of the University of Massachusetts Medical School and Nobel Laureate for medicine in 2006 for his genetics research.

Opacity and scientific competition

Some scientists are reluctant to be critical of He and suggest his studies, which resulted in the first CRISPR babies, simply signal the “next chapter in the technology’s story”. He Jiankui appears to be an ambitious scientist desperate to become the first to conduct the gene editing experiment on humans, but who made some significant errors of judgement by initiating his study prematurely and by withholding information from regulatory authorities and his university. A generous interpretation might suggest that He was motivated by science and humanity. Through a Beijing-based organization, which helps Chinese people with HIV, he recruited couples for his experiment where only the fathers were living with HIV infections, which they managed by antiviral drugs. Eight couples agreed to participate, although one subsequently withdrew.

Since He’s statement at the Hong Kong conference he has disappeared, but the background to his studies has been well documented. In late 2017, He, who specialized in sequencing DNA, began his efforts to produce human babies from gene edited embryos and before and during his study it is reported that he sought advice from international experts in the field and communicated openly with international colleagues about his plans. Notwithstanding, it is alleged that He faked a blood test for one of the fathers in the study, aware that in China the HIV status of the father would disqualify him from participating in fertility treatments. Also, He failed to appropriately inform the hospital where the twins were edited and implanted of the status of his experiments.

You might also like:

Will China become a world leader in health life sciences and usurp the US?

Fierce competition among scientists is not uncommon and competition fuels opacity among scientists in their battle to become the first to make a discovery. Indeed, it is not uncommon for scientists to shield their ideas and research. This does not condone He’s actions, but it might help to explain them. Generally speaking, scientific opacity is not created by ambitious scientists alone, but it is partly created by scientific funding bodies and research institutions. Such opacity is a significant obstacle to open collaboration. In addition to wanting to be the first, He’s intentions might also have been an attempt to spare children of parents with HIV/AIDS from inheriting the disease.

CRISPR is not yet safe

Be that as it may, many scientists agree that CRISPR is not yet safe and precise enough to be used in human embryos. In the March 2019 edition of Nature a group of 18 prominent CRISPR scientists and bioethicists from seven countries called for a global moratorium on heritable genome editing until the establishment of an international framework that would compel countries to establish both scientific safety and broad societal agreement before allowing the technology to progress. "We call for a global moratorium on all clinical uses of human germline editing; that is, changing heritable DNA (in sperm, eggs or embryos) to make genetically modified children" , the scientists wrote.

Opposition to germline editing is mixed

However, opposition to germline editing is mixed. In February 2017 the US National Academies of Sciences, Engineering, and Medicine (NASEM) published a report, which did not call for an international ban of germline editing, but instead suggested that it "might be permitted" if strict criteria were met. In July 2018, the UK’s Nuffield Council of Bioethics published a report on heritable genome editing and suggested that under certain circumstances it could be morally permissible, even in cases of human enhancement.

Given that CRISPR is cheap, easy-to-use and already an effective tool in thousands of laboratories throughout the world, it seems reasonable to assume that standards and laws are unlikely to prevent a determined scientist and desperate patients from using the technology prematurely. Indeed, science and medicine have a history of researchers attracting public criticism for undertaking experiments prematurely only to have those experiments become common medical practices: in-vitro fertilization (IVF) is one such example. Although IVF has a chequered history today it accounts for millions of births worldwide and 1% to 3% of all births every year in the US and Europe.

Germline engineering and somatic genetic modification

Here we describe the difference between germline and somatic adjustments. The former uses CRISPR to modify DNA in such a way that the change is heritable. The latter uses CRISPR to modify the DNA of people with incurable diseases in a way that such modifications are limited to the people treated and not passed on to future generations. Broadly speaking, your body has two kinds of cells: somatic and germ cells. The vast majority are somatic. These cells make up your body and are responsible for forming all your familiar structures: such as your skin, blood, muscles and organs etc. Your somatic cells die when you die so there is no chance of them creating a new organism. However, germ cells are different. Early in your development your germ cells are sequestered: they divide more slowly and under restricted circumstances. Germ cells cannot become a physical feature such as an ear or a finger, but they do make the only bits of you, which can form a new person: your eggs and your sperm. Every cell in your body holds your DNA in an unbroken lineage stretching back millions of years and thousands of generations, but only the germline has a chance to go forward. Human germline modification means deliberately changing the genes passed on to children and future generations and thereby creating genetically modified people. Somatic genetic modification is different. It adds, cuts, or changes the genes in some of your cells, typically to alleviate a medical condition. The use of human genome editing to make edits in somatic cells for purposes of treating genetically inherited diseases is already in clinical studies. If perfected, somatic gene editing (gene therapy) holds promise for helping people who are sick, affecting only an individual consenting patient. With the exception of He’s studies, human clinical studies with CRISPR have been limited to somatic cells. In effect, this renders CRISPR no more consequential than any other experimental drug or treatment. Any CRISPR-made somatic cell changes are a genetic dead-end and are not heritable. However, germline cells have the possibility of immortality, with the potential to affect thousands of people over the course of several generations. Tampering with germline cells is therefore a much more serious proposition.

Clinical studies of gene therapies

Gene therapy is primarily available in a research setting. The US Food and Drug Administration (FDA) has approved only a limited number of gene therapy products for sale in the US.According to the US National Institutes of Health, which serves as a clearinghouse for biomedical research worldwide, there are over 800 clinical studies currently underway to test gene therapy as a treatment for genetic conditions. The list includes a relatively small number of CRISPR studies as a treatment for cancers of the lung, bladder, cervix and prostate, the majority of which are in China where doctors appear to be leading the race to treat cancer by editing genes. For the past two decades China has been investing heavily in biomedicine. It is one way that China is able to compete with the West and demonstrate its technological prowess in the 21st century. Also, it is important for China to keep its vast population healthy in the 21st century. Given the somewhat ambiguous state of CRISPR technology it seems reasonable to assume that the first therapeutic applications of CRISPR will be in diseases where cells can be taken out of your body, edited, checked to ensure they are safe and then reintroduced. This suggests blood disorders such as sickle cell or thalassemia.

Takeaways

Bioethicist Henry T (Hank) Greely, professor at Stanford University, California, US, compares CRISPR to the Model T Ford, which was not the first automobile, but because of its simplicity of production, dependability and affordability it transformed society. CRISPR is not the first gene editing technology, but it is cheap and easy to use and is on the cusp of transforming biomedicine. A significant challenge is getting CRISPR tools, which are capable of performing gene edits, into the right place and to ensure they are safe. Prime editing is a smart, innovative and a substantial step forward in achieving this. Indeed, David Liu and his colleagues from the Broad Institute have expanded the gene editing toolbox to facilitate ever-more precise editing ability and efficiency. Significantly, the overwhelming majority of human genetic disorders are due to the types of mutation that prime editing is able to correct, which stands the technique in good stead to be useful in therapies for intractable diseases. Notwithstanding, it is one thing to cut out sequences of DNA that cause genetic diseases and another to make genetic changes that are passed down to all later generations. Because CRISPR is cheap, easy-to-use, in the hands of scientists throughout the world, and already has been used to create babies with heritable traits, the technology provokes deep ethical and societal debate about what is, and what is not acceptable in efforts to prevent disease. Given that CRISPR has the potential to change the nature of humanity, it is incumbent on all citizens, not just scientists, bioethicists and regulators, to call for open and inclusive processes associated with all aspects of CRISPR.

expand

view in full page

6 years, 5 months ago

36194
0
Facebook

Twitter

Google+

LinkedIn

Report

CRISPR-Cas9 genome editing a 2-edged sword

HealthPad

Directory:

Medical Technology

Tags:

incurable inherited diseases

CRISPR-Cas9 genome editing technology discovered in 2012 has revolutionized biological science and brought hope to millions of people born with incurable inherited killer diseases
In July 2018 the UK’s Nuffield Council on Bioethics endorsed the technology to make changes at the cell level in the human body that are heritable
This alarms bioethicists because there is no universally agreed regulation for CRISPR and the technology is cheap, easy-to-use and accessible and the line between “therapy” and “enhancement” is blurred
CRISPR was invented in the West but is rapidly being transformed into therapies in China where regulation is less than stringent
Will genome editing be used to enhance off-springs that satisfy parents’ preferences for children with specific characteristics?

CRISPR-Cas9 genome editing a 2-edged sword

The genie is out of the bottle!

On the 17^th July 2018 the UK’s Nuffield Council on Bioethics published a report entitled, Genome Editing and Human Reproduction: Social and Ethical Issues, which concluded that germline editing, a process by which every cell in the human body could be altered in such a way that the change is heritable, is “morally permissibly” under certain circumstances. The Council was referring to developments of an invention made in 2012 by scientists Jennifer Doudna, and Emmanuelle Charpentier. They discovered how to exploit an oddity in the immune system of bacteria to edit genes, which resulted in CRISPR-Cas9, (an acronym for Clustered Regularly Interspaced Short Palindromic Repeats), which is generally considered the most important invention in the history of biology. Since its discovery, modified versions of the technology have found a widespread use to engineer genomes and to activate or to repress the expression of genes. Clinical studies testing CRISPR-Cas9 in humans are underway.

In this Commentary

In this Commentary we: (i) describe CRISPR-Cas9 and indicate how it has impacted medicine, biotechnology and agriculture, but suggest that it is most famous for its potential to modify human embryos to provide therapies for inherited killer diseases for which there are no known cures, (ii) suggest that although the technology is gaining regulatory support for its use in humans, there is no universal regulatory agreement. Some countries remain opposed to using CRISPR to edit human embryos while in China regulations is less than stringent. This patchy and loose state of affairs raise concerns among bioethicists, (iii) describe a non-profit agency that has significantly increased the accessibility of the technology, which has helped to democratise CRISPR, but also makes it easier for less stringently controlled laboratories to acquire it, (iv) briefly describe the Chinese scientists first use of the technology in humans and some of the unintended consequences which resulted. We provide examples of research that followed and briefly describe the US-China race to transform CRISPR into viable therapies, and suggest that China, helped by laxed regulation, is winning the race, (v) suggest that these factors, plus the fact CRISPR blurs the distinction between ‘therapy’ and ‘enhancement’, seems to convince bioethicists that the technology at some point in the future will be used to create ‘designer babies’, (vi) conclude by noting that for millennia people have been using radical and painful methods to modify their own and their children’s bodies and this seems to suggest that in time, germline editing will be perceived as a logical extension of these customs and practices, the genie is out the bottle and customize children are likely to become the norm.

CRISPR-Cas9

CRISPR is a mechanism deployed by bacteria to identify the DNA of invading viruses and is used by scientists to target a specific gene. Cas-9 is an enzyme, which acts like a pair of molecular scissors to cut out a piece of DNA and, if need be, replace it with a new gene. The process is faster, cheaper and easier to use than traditional genetic modification and has been likened to editing a Word document on a computer. Thus, gene editing has been taken away from highly skilled and tightly regulated molecular biologists and made more widely available. This not only democratizes science but also heightens ethical concerns.

CRISPR technologies impact medicine biotechnology and agriculture

Since the breakthrough was made in 2012, CRISPR-Cas9 has quickly development into a powerful, cheap and accessible tool in genetics. The technology is programmable, efficient, precise and scalable and has driven significant advances across medicine, biotechnology and agriculture throughout the world. As the world’s population and average temperatures increase, the demand for larger, more nutritious harvests and climate-adaptable crops will grow. The application of CRISPR technology to agriculture allows for an efficient and accurate mode of genetic manipulation to meet these increasing needs. The technology also has been used in the fight against malaria. According to a 2018 World Health Organization report, in 2016 there were 216m cases of malaria worldwide and 445,000 deaths from the disease. Malaria is spread by the female Anopheles-gambiae mosquito, which is one of 3,500 species of mosquitoes. Scientists have used CRISPR technology to edit the genes of this specific type of mosquito to avoid the malaria causing parasite. In a study carried out at Imperial College London and published in the September 2018 edition of Nature Biotechnology researchers succeeded in destroying a population of trapped Anopheles mosquitoes by using CRISPR technology to genetically alter cells to spread a genetic modification that blocks female reproduction so, over time, the malaria spreading Anopheles mosquitoes die out. The research demonstrates how a specific CRISPR application can propagate a particular suite of genes throughout an entire population or species and empower scientists in the war against diseases. “It provides hope in the fight against a disease that has plagued mankind for centuries,” says Andrea Crisanti, lead author of the Imperial study.

But the one application, which has made CRISPR famous is the modification of the human genome, which promises to cure some of the world’s deadliest diseases for which there are no known therapies. There are some 10,000 genetic diseases of which less than 6% have approved treatments.

Regulatory support

CRISPR genome editing technologies have been gaining regulatory acceptance for their use in humans and an increasing number of scientists in the US, UK and China have reached conclusions similar to those of the Nuffield Council, and suggest that if germline editing is shown to be safe and there are no medical alternatives, it should be permitted to prevent children being born with fatal diseases. In 2017, the UK’s Human Fertilization and Embryology Authority approved an application to use genome editing, which allows scientists to change an organism’s DNA in research on human embryos. Also, in 2017 a report from the US National Academy of Sciences (NAS) stated that clinical trials for editing-out heritable diseases could be permitted in the future for serious conditions under stringent oversight. At the same time as the Nuffield Council published its findings, - July 2018 - the US Food and Drug Administration (FDA) Commissioner Scott Gottlieb announced a new regulatory framework for genome editing for rare diseases. The following month, - August 2018 - the FDA along with the US National Institutes of Health (NIH) issued joint guidelines for a new streamlined process for assessing the safety of gene-therapy human clinical studies. And in an August 2018 New England Journal of Medicine editorial Gottlieb and NIH Director Francis Collins argue that, “there is no longer sufficient evidence to claim that the risks of gene therapy are entirely unique and unpredictable - or that the field still requires special oversight that falls outside our existing framework for ensuring safety.”

No international regulatory framework for CRISPR triggers concerns

Despite increasing support for genome editing, to-date no internationally agreed regulatory framework exists that addresses the ensuing scientific, socio-ethical and legal challenges CRISPR technologies pose for regenerative and personalised medicine. Regulation is on a country-by-country basis and most nations struggle to assess whether gene editing may or may not be different from classical genetic engineering. Several nations remain opposed to the use of the technology in humans. The most contentious issue is human germline editing.

In Canada human germline editing is a criminal offence and sanctions range from fines of US$400,000 and up to ten years imprisonment. However, there is mounting pressure from Canadian scientists to change the law. France restricts genome editing research and supports the Oviedo Convention, which is the first multilateral binding instrument entirely devoted to bio-law. It came into force in 1999, backed by the Council for Europe and aims to prohibit the misuse of innovations in biomedicine. The treaty states that, “An intervention seeking to modify the human genome may only be undertaken for preventive, diagnostic, or therapeutic purposes and only if its aim is not to introduce any modification in the genome of any descendants”. In Germany germline editing is constrained by its 1990 Embryo Protection Act, which prohibits the generation and use of embryos for basic research, and also prohibits the harvesting of embryonic cells. South Korea’s Bioethics and Biosafety Act prohibits genetic experimentation, which modifies human embryos. Western observers suggest that regulation in China is “thin” and tends to be at the provincial and hospital levels. It has been reported that Chinese hospital review boards have approved clinical studies involving gene-editing and cancer patients without fully understanding the nature and power of the technology.

The “dark-side” of CRISPR technology

Weak regulation raises concerns about the level of ethical conduct in clinical studies and the potential dangers this holds for future therapies. Cognisant of CRISPR’s powerful capabilities, its relative cheapness and accessibility, (see below) James Clapper, the former US Director of National Intelligence describes CRISPR-Cas9 gene editing in the 2016 and 2017 Agency’s Worldwide Threat Assessment reports submitted to the US Congress as, “a potential weapon for mass destruction”. Jennifer Doudna, one of the inventors of CRISPR-Cas9 says that there are things which you would not want the technology used for and, “most of the public does not appreciate what is coming”. These sentiments resonate with bioethicists concerned about the absence of stringent universal regulation and the technology getting into the “wrong hands” and resulting in “designer babies”, an escalation of societal inequalities and increased safety and biosecurity issues.

You might also like:

The global competition to translate genomic data into personal medical therapies

PART 1

and

PART 2

Democratizing the CRISPR technology

Notwithstanding, many scientists view the ease of access to CRISPR technologies as a significant driver of cutting-edge research and the speed at which therapies for life-threatening diseases will enter clinics. The organization most responsible for CRISPR’s widespread accessibility is Addgene, a self-sustaining, non-profit plasmid repository, which facilitates the exchange of genetic material between laboratories throughout the world. (A plasmid is a small DNA molecule within a cell that is physically separated from a chromosomal DNA. It can replicate independently and is used in the laboratory manipulation of genes). It is free for scientists to deposit plasmids in Addgene and a nominal fee is charged for requests. This allows for maintenance and growth of the repository without reliance on grants or external funding. Founded in 2004, Addgene has significantly reduced the frustration scientists experience sharing plasmids with one another. The organization has developed into an important one-stop-shop for depositing, storing, and distributing plasmids globally and this has significantly enabled the democratization of CRISPR technologies. More than 6,300 CRISPR-related plasmids have been developed by over 330 academic laboratories throughout the world and deposited with Addgene. Since 2013, the organization has distributed over 100,000 CRISPR plasmids to some 3,400 laboratories in more than 75 countries.

Mixed results when CRISPR was first used in humans

CRISPR technology was first used in humans in China, when a group of scientists led by Junjiu Huang from Sun Yat-sen University in Guangzhou, attempted to modify the gene responsible for β-thalassemia, a potentially fatal blood disorder. Although the genomes of human embryos edited by the scientists could not be developed into a foetus, the researchers had difficulties publishing their findings because of ethical concerns. After being rejected by the journals Science and Nature their paper was published in 2015 in the journal Protein & Cell. The work triggered an international debate, but the research had a low success rate: only 4 of the 54 embryos that survived the technique carried the repaired genes. Huang and his colleagues identified two challenges. One was unintended genetic modifications - off target effects - when CRISPR either changes a gene scientist did not want changed or it fails to change a gene that they did. The second was that embryos, which did not get edited correctly mixed with those that did and became what is referred to as a “mosaic”.

New study discovers the deletion of thousands of DNA bases

Initially, these anomalies were thought to be minimal and improvements to the technique were thought to be able to reduce them so that they were virtually undetectable. Indeed, since 2015 the science of human genome editing has advanced significantly and there has been an explosion of research. In 2017 alone, there were some 3,500 research papers published on CRISPR technologies but concerns about CRISPR’s accuracy remain. During the past three years of intense research CRISPR-Cas9 became popularly perceived as a technique that can edit genetic code to correct defects inside individual cells and prevent and heal many intractable illnesses. Notwithstanding, also there has been a growing concern among scientists that because Cas9 enzymes reprogram the DNA of a cell, which is the fundamental building block for the development of an organism, the technique, if inaccurate, may cause more harm than good. Recent research supports this view. A study published in the July 2018 edition of the journal Nature Biotechnology discovered deletions of thousands of DNA bases, including at spots far from the edit. Some of the deletions can silence genes that should be active and activate genes that should be silent, including cancer-causing genes. This suggests that previous methods for detecting off-target mutations may have underestimated their true scale and therefore the potential for unintended consequences when using CRISPR technologies might be higher than originally thought. This finding poses a significant challenge for developing policy associated with CRISPR because you do not know what off-target effects will occur in humans until you use the technology.

Who is developing CRISPR-Cas9 therapies?

Notwithstanding, CRISPR–Cas9 is fast entering mainstream R&D and is perceived as a principal technology for treating diseases with a genetic basis and is increasingly playing a significant role in drug discovery. Scientists use the technology to either activate or inhibit genes and can determine the genes and proteins that cause or prevent specific diseases and thereby identify targets for potential therapies. Notwithstanding, drug development is a long and expensive process: it can take more than a decade and cost some US$2bn for researchers to move from the discovery of a target molecule to the production of a clinically approved therapy. So, it could be some time before the first drugs using CRISPR–Cas9 gene editing make it to the clinics. Notwithstanding, a lot has been achieved in a relatively short time.

Research examples

UK examples of research using CRISPR technology include scientists from the Huntington’s Disease Centre at University College London’s Institute of Neurology, who in 2017 completed the first human genetic engineering study, which targeted the cause of Huntington’s disease and successfully lowered the level of the harmful huntingtin protein that irreversibly damages the brains of patients suffering from this incurable degenerative condition. In another study using CRISPR technology and published in a 2017 edition of the New England Journal of Medicine, researchers from Barts Health NHS Trust and Queen Mary University London made a significant step towards finding a cure for haemophilia A, a rare incurable life threatening-blood disorder, which is caused by the failure to produce certain proteins required for blood clotting.

Human clinical studies

Although CRISPR has proved its worth as a research tool, its use as a therapeutic is still uncertain. This is partly because the technology is so new there is a dearth of data upon which to base clinical evaluations. Notwithstanding, since Chinese scientists first used CRISPR to edit a human embryo's genome, new and more accurate variants of CRISPR have been developed. At about the same time - 2015 - that Huang published his findings using CRISPR for the first time in humans, two children with Acute Lymphoblastic Leukaemia, an incurable cancer, were treated at Great Ormond Street Hospital (GOSH) in London with a version of CRISPR called CAR-T cell therapy. This entails extracting blood cells from patients, then using CRISPR technologies to edit the T cells outside the body - ex vivo gene therapy - in order to transform the cells into enhanced cancer fighters before reintroducing them back into the patient’s blood stream. The treatment proved to be such a success that in 2018 CAR-T cell therapy was made available on the NHS. A US clinical study using the same technique started in August 2018 for people with Acute Lymphoblastic Leukaemia.

Over the past three years scientists in China have used newer versions of CRISPR to genetically engineer cells of at least 86 cancer and HIV patients. These cases form part of eleven human clinical studies using CRISPR-Cas9 technologies, ten of which are being undertaken in China. Another development of CRISPR is ‘base-editing’, which chemically modifies rather than cuts DNA. An August 2018 edition of the journal Molecular Therapy, describes how scientists in China used base editing, to remodel the DNA of human embryos to treat patients with the Marfan syndrome, which is a relatively common inherited connective tissue disorder with significant morbidity and mortality. A further milestone for the technology was reported 2018 when a study, led by Zheng Hu of the First Affiliated Hospital, Sun Yat-Sen University, Guangzhou, Guangdong, China, was the first to edit human cells while inside the body in an attempt to eliminate the human papilloma virus, which is the main cause of cervical cancer.

Company activity and clinical studies

Since the first publications in 2012 showcasing CRISPR-Cas9 as a gene editing tool, a number of companies have been set up to leverage the technology to develop innovative therapies. For example, Editas Medicine, was founded in 2013 by Feng Zhang, Jennifer Doudna, David Liu, George Church, and J.Keith Joung. However, just a few weeks after the company’s formation, Doudna stopped all involvement with Editas after Zhang was granted a number of CRISPR patents and issues concerning intellectual property began to appear. In October 2018 Editas filed an Investigational New Drug (IND) application with the US Food and Drug Administration (FDA) for a clinical study of a CRISPR genome editing medicine called EDIT-101 for the treatment of Leber Congenital Amaurosis type 10 (LCA10). This is a serious eye disorder that affects the retina, which is the specialized tissue at the back of the eye that detects light and colour. People with LCA10 typically have severe visual impairment from infancy.

In 2018 the European Patent Office granted Cellectis, a French biopharmaceutical company, the first patent to use CRISPR technology in human T cells.The patent will protect the application of CRISPR gene editing for T cell research until 2034, meaning every other company employing similar systems will need a license from Cellectis. Also, in 2018 CRISPR Therapeutics, co-founded by Emmanuelle Charpentier began a clinical study using CRISPR genome editing technologies and a similar ex vivo approach to target the blood disorder β-thalassemia. As yet no CRISPR therapies have reached the clinic.

US-China competition

There is intense and growing scientific competition between the US and China. Although CRISPR was invented in the West, it is more rapidly being transformed in China into therapies that can be used in clinics. An article in a January 2018 edition of the Wall Street Journal suggests that regulation governing genome editing of human embryos in China is much less stringent than in the West where researchers have to pass muster with hospital review boards, ethics committees and government agencies before receiving approval. In China it is not unusual simply for hospital committees to give such permissions. According to Carl June, director of translational research at the Abramson Cancer Center, University of Pennsylvania and well-known for his research into T-cell therapies for the treatment of cancer, “We are at a dangerous point in losing our lead in biomedicine. It is hard to know what the ideal is between moving quickly and making sure patients are safe”. Western scientists believe that the less that stringent regulation in China gives Chinese researchers a significant competitive advantage in the race to get CRISPR therapies into clinics and bioethicists believe that loose regulation will result in unintended consequences that will harm patients and lead to “designer babies”, which could set-back the field for everyone.

Blurred line between therapy and enhancement

What makes regulation challenging is that CRISPR technologies blur the distinction between “therapy” and “enhancement”. Indeed, the 2018 Nuffield Council report referred to at the beginning of this Commentary suggests that such a distinction between therapy and enhancement cannot be expected to hold. Thus, it seems reasonable to assume that sometime in the future, CRISPR technologies, which are cheap, easy to use and accessible could be used to genetically enhance off-springs. In the first instance this solely might be focused on eradicating life-threatening diseases, but in the longer term it seems probable, especially in the absence of any universally agreed and tightly administered regulations, that genome editing will be used to create off-springs, which satisfy parents’ preferences for children with specific characteristics. Further, CRISPR technology is becoming popular among DIY scientists and biohackers – people who experiment on themselves - which exacerbates the concerns of bioethicists.

People have been radically altering bodies for millennia

Another reason to believe that germline editing will be used for ‘cosmetic’ enhancements rather than medical therapies is that for millennia people have used radical techniques to modify their own and their children’s bodies for cosmetic rather than therapeutic purposes. Here we illustrate the point with a few examples.

From the Song dynasties, which ruled China between 960 and 1279 until the early 20th century, the Chinese practiced the custom of breaking their first daughter’s toes and tightly binding them under the soles of their feet in order to stunt growth so that when the girl grew up she would walk diffidently, which was perceived as attractive. In England during the Victorian era between the mid 19^th and the beginning of the 20^th century, women, to make themselves attractive to men, corseted their bodies so tightly to create twelve-inch waists that their internal organs were redistributed with potentially dangerous consequences. Girls as young as 4 from the Kayan tribe of Myanmar use heavy brass coils to elongate their necks; a painful tradition dating back to the 11^th century. The brass coils, that weigh an average of 10 kilos, deform their collar bones and neck and shoulder muscles. The Mursi tribe in Africa cut the lower lips of girls and insert plates to stretch the lips up to 12 cm in diameter.

In the 1970s and 1980s elective cosmetic surgical procedures gained popularity among wealthy people on the East and West coasts of America in order to enhance their appearance. The trend soon became global through the explosion of mass media. According to the International Society of Aesthetic Plastic Surgery in 2017 there was a 9% overall annual increase in surgical and nonsurgical cosmetic procedures globally. The US was the leader, accounting for 17.9% of all procedures. The top five countries were the US, Brazil, Japan, Italy and Mexico, which together accounted for 41.4% of all cosmetic surgical procedures worldwide. Russia, India, Turkey, Germany and France completed the top ten countries. In 2017, 400,000 American women elected to have breasts augmentation surgery; a 41% increase since 2000. About 1m rhinoplasties are carried out each year, with high volumes in Brazil and Mexico. The International Society of Aesthetic Plastic Surgery also reported that in 2016 surgeons in South Korea carried out the most cosmetic surgical procedures per capita: 20 per 1,000 people. V-shaped chins, with minimal jaw or cheekbone, round skulls, lifted lip corners, petite lips and slight puffiness under the eyes have been popular surgeries in South Korea, but recently the demand for such procedures has decreased while simpler and less invasive surgeries have increased. The Society also reported that labiaplasty showed the biggest (45%) increase since 2015. Lower body lift procedures increased by 29%, while upper body lift, breast augmentation using fat transfer, and buttock lifts increased by some 20%.

Such examples suggest that body enhancements, using a range of techniques, have been practiced in many cultures throughout the world for millennia. Thus, it seems reasonable to assume that in the absence of stringent regulation CRISPR will be perceived by some as just another enhancement technique.

Takeaways

The discovery of CRISPR Cas9 has revolutionized the way we think about developing therapies for the world’s deadliest diseases. This powerful technology has significant advantages over traditional medical technologies; it is cheap, easy-to-use and accessible, and these factors have helped to drive CRISPR’s global acceptance and use as a tool for new and innovative therapies. Over the past three years CRISPR R&D and clinical studies have developed at a pace and bring huge promise and significant hope to millions of people living with conditions with high rates of morbidity and mortality. Notwithstanding, bioethicists warn that with the absence of stringent universally agreed regulation, all these advantages could easily pivot into significant disadvantages and lead to parents enhancing the genetic composition of their children to make them taller, more intelligent etc. This could be a small step away from reigniting the ‘Charles Galton movement’. Galton was an English scholar and cousin of Charles Darwin. He lived during the Victorian era and died in 1911. Among other things, Galton studied anthropology and sociology and suggested that the elevated social position and heightened intelligence of the English upper classes and the criminality and lack of intelligence of the English under classes were all inherited traits and the result of superior and inferior genetic make-up respectively. According to Galton societies could be improved by selective breeding. Bioethicists are concerned that CRISPR technologies could be used for a 21^st century version of Galtonism.

The genie is truly out of the bottle.

expand

view in full page

6 years, 5 months ago

34580
0
Facebook

Twitter

Google+

LinkedIn

Report

Base-editing next-generation genome editor with delivery challenges

HealthPad

Directory:

Medical Technology

Tags:

‘Base editing’ is a more efficient version of CRISPR Cas-9 technology
CRISPR Cas-9 is a ground-breaking gene editing technology that was discovered in 2012
CRISPR Cas-9 operates like molecular scissors to cut and remove mutant strands of DNA and creates space for functioning genes to be inserted
CRISPR technologies raise hope for new therapies to replace traditional medicines and provide a one-time procedure to cure devastating inherited disorders that have no cure or few treatment options
Recent studies suggest that CRISPR Cas-9 is not as accurate as initially thought and can introduce thousands of unintended ‘off-target’ mutations into the genome
Base editing significantly reduces ‘off-target’ mutations because it does not cut the DNA but uses a chemical process to convert just one letter (base) of DNA into another
66% of genetic illnesses involve mutations where there is a change in a single letter of DNA
A significant challenge for base editing is in the delivery of the technique

Base-editing next-generation genome editor with delivery challenges

Since the first human genome was sequenced in 2003 there has been a revolution in human genomics, which has transformed the way we think about diseases and their causes and has paved the way for the development of therapies that target both the illness and the patient. It has also led to the introduction of the genome-editing tool CRISPR Cas-9 in 2012. This transformed gene editing from a devilishly difficult task to an easy and inexpensive “day-to-day” laboratory technology, which allows scientists to cut-out and change sections of DNA at specific sites in an organism or cell. CRISPR technology revolutionized genetic research and raised hope that it could provide a powerful therapeutic tool for millions of people living with inherited debilitating diseases for which there are either no cures or few treatment options. Recently, next-generation gene-editing technologies have been developed, which have reignited the hope that gene therapies could eventually replace traditional medicines and be used by physicians in clinics as a one-time procedure to cure some of the most devastating inherited disorders. Notwithstanding, scientists have cautioned that the therapeutic use of CRISPR technologies have significant technical, safety, regulatory, ethical and delivery obstacles to overcome before they can be used as therapies.

In this Commentary

This Commentary describes a new and expanded gene editing technology called base editing or chemical surgery, which compliments CRISPR Cas-9, but instead of cutting strands of DNA it provides a more accurate and predictable means to rewrite single letters (bases) of DNA and RNA. This enables scientists to make more targeted and precise alterations to DNA and RNA with less unintended consequences, referred to as “off-target” effects. Base editing has significant therapeutic potential for thousands of human disorders known to be caused by a single genetic error and range from sickle-cell anaemia to metabolic disorders to cystic fibrosis, which currently lack options. The new base editing techniques are described in three research papers, which appeared in scientific journals in late 2017. One was published in the November 2017 edition of the journal ‘Protein and Cell’, another in the October 2017 edition of the ‘Nature’ and a third in the October 2017 edition of the journal ‘Science’. Research reported in these papers represents an important advance in our ability to alter single letters (bases) in peoples’ DNA and RNA. Notwithstanding, scientists caution that before base editing techniques become standard clinical practice the technology will require more research, extensive clinical studies and significant advances in delivery methods.

CRISPR and intellectual property battles

Base editing is a development of CRISPR Cas-9 technology, which was developed by a group of researchers from University College Berkeley, the Max-Plank Institute, Harvard University and The Massachusetts Institute of Technology (MIT) and others. The Broad Institute, a non-profit disease research facility established jointly by Harvard University and MIT, obtained the basic US patents on CRISPR Cas-9 in February 2017 after a heated patent dispute between two of the technology’s originators. On one side Jennifer Doudna of University College Berkeley and Emmanuelle Charpentier of the Max-Planck Institute in Berlin. On the other side Feng Zhang of the Broad Institute. While the Broad Institute has been considered the winning party in the US, the European intellectual property landscape is a different story. Due to technical errors associated with listed CRISPR inventions and claimed priority dates, the European patents filed by the Broad Institute have been revoked.

The Broad Institute is expected to appeal the decision and the gene-editing intellectual property battles continue. Notwithstanding, this has not slowed the development and commercialization of the technology.

Technologies to edit the genetic code and some ethical challenges

CRISPR Cas-9, discovered in 2012, is a particularly versatile and inexpensive gene editing technology. Since its discovery it has been used extensively by scientists throughout the world in an attempt to further their understanding of the role played by genes in disease. The technology works by slicing through the two strands of bases that spiral to create DNA’s famous double-helix and is especially useful when the goal is to insert or delete DNA bases. CRISPR acts like a genetic GSP: a guide molecule made of RNA that allows a specific site of interest on the DNA double helix to be targeted. The RNA molecule is attached to a bacterial enzyme called Cas-9 that works like a pair of “molecular scissors”, which can cut out strands of DNA at an exact point. This allows scientists to target and remove faulty genetic material and create space for functioning genes to be inserted in a similar way a word processor allows you to correct and enhance documents. Although CRISPR Cas-9 is increasingly being used in studies of genetic disorders, it has been challenging for the technology to fix a point mutation, caused by a change in a single DNA letter in a given gene. Further the technology’s cutting mechanism can result in “off-target” activity, which either can make changes to a gene you do not want changed or fail to change a gene that you do. This represents a significant challenge for scientists, and a major concern for the technology’s therapeutic applications.

For example, research published in the July 2018 edition of the journal Nature Biotechnology discovered unintended deletions of thousands of DNA bases, including at spots far from the edit. Another study reported in the May 2017 edition the journal Nature Methods found that CRISPR Cas-9 introduced hundreds of unintended mutations into the genome. And a third study published in December 2017 in the Proceedings of the US National Academy of Sciences suggested that genetic variation between patients may affect the efficacy and safety of CRISPR-based treatments enough to warrant custom treatments. In addition to these technical concerns, ethical concerns about the technique also have been raised. In the March 2015 edition of the journal Nature, Michael Werner, the executive director of the Washington DC based Alliance for Regenerative Medicine suggested that ethical and safety issues should put germline editing research (a process by which every cell in the human body could be altered in such a way that the change is heritable) off limits because, “It’s still a little premature to say that we’ve resolved all these safety issues now,” says Werner. Notwithstanding, in July 2018 the UK’s Nuffield Council on Bioethics suggested that germline editing is “morally permissibly” under certain circumstances.

CRISPR triggers intense commercial activity

Despite safety and ethical concerns about CRISPR, genome editing has rapidly become a large fast-growing global market. In late 2012, Charpentier suggested to a few colleagues, including Doudna, Zhang and George Church, professor of genetics at Harvard University Medical School who is credited with developing the first direct genomic sequencing method in 1984, that they should start a company to accelerate the gene editing technology into clinics. They did not, but later the same scientists and others started separate genome editing companies. Four have become publicly traded companies and have successfully raised billions. For example, in 2013 Charpentier founded Crispr Therapeutics. Based in Switzerland, the company has become a US$2bn Nasdaq traded company. The other three, all based in the US are: Editas Medicine, which has a market cap of US$1.3bn and was founded by Zhang, Church and David Liu, Professor of Chemistry at Harvard University, a core member of the Broad Institute, and the first to describe base editing in research published in the May 2016 edition of the journal Nature. Doudna is a founding member of Intellia Therapeutics, which today has a market cap of US$1bn, and Juno Therapeutics, which has a market cap of US$10bn was founded in 2013 through a collaboration of the Fred Hutchinson Cancer Research Center, Memorial Sloan-Kettering Cancer Center and the Seattle Children’s Research Institute.

Since their inceptions, big pharma companies have been competing to invest in them. In January 2018 Celgene, which already owned 9.7% of Juno agreed to acquire the rest of its stock for US$9bn in cash in order to gain access to Juno's pipeline of CAR-T cancer drugs. This technology entails extracting blood cells from patients, then using CRISPR to edit T cells (immune cells) outside the body - ex vivo gene therapy - in order to transform the cells into enhanced cancer fighters before reintroducing them back into the patient’s blood stream. Earlier Bayer, a German pharmaceutical company, acquired a US$35m equity stake in Crispr Therapeutics, which it increased in January 2018. In 2016 Bayer invested US$335m over 5-years in a joint venture with Crispr Therapeutics called Casebia, with the intention to discover, develop and commercialize new breakthrough therapeutics to cure blood disorders, blindness, and congenital heart disease. Casebia also expects to develop new delivery mechanisms for CRISPR technologies, which will be critical to future drugs meant to target cells in the human body. Crispr Therapeutics retains a 50% interest in the joint venture, and also gains access to Bayer’s state-of-the-art delivery technologies and protein engineering knowhow.

According to market analysis the global genome editing market is expected to grow at a CAGR of 14.5% to reach US$6.3bn by 2022. Market drivers include rising government funding and the growth in the number of genomic projects, high and increasing prevalence of debilitating and often fatal diseases, technological advancements, increasing production of genetically modified crops, and growing application areas of genomics.

You might also like:

CRISPR positioned to eliminate human papilloma viruses that cause cervical cancer

Tens of thousands of devastating diseases are the result of a single minute error in one letter the human genome

While big pharma competes to commercialize CRISPR Cas-9 technologies, scientists compete to develop ever-more versatile and efficient versions of the technology. One result of the competition among scientists is “base editing”, which is predicated upon the same basic mechanism as the standard CRISPR technology but differs because it does not require the DNA to be physically cut. Instead, base editing uses a chemical process to directly convert a single base (letter) of DNA to another without deleting and inserting random bases in the process. Think of base editing as similar to changing one letter in a vast WORD document. The technique allows scientists to edit the body’s genes one letter at a time with exquisite precision. Base editing rewrites single errors in the genetic code instead of cutting and replacing whole strands of DNA. The technique is not a replacement for CRISPR, but a complementary technology for altering the genome in an attempt to correct disease. Converting one letter to another may not sound significant until you consider that there are billions of letters in the human genome, and tens of thousands of diseases can be traced to a single minute error in just one letter in the human genome. Indeed, of more than 50,000 genetic changes currently known to be associated with disease in humans, 32,000 are caused by the simple substitution of one base letter for another. Base editing is significantly more efficient than standard CRISPR systems at making single base substitutions.

DNA molecules as a sequence of letters

Your genes are an instruction manual for your body. Hidden inside every cell in your body is a chemical called DNA. Genes are short sections of DNA, which are the biological templates your body uses to make the structural proteins and enzymes needed to build and maintain your tissues and organs. Genes influence how you look on the outside and how you function on the inside. The DNA that makes up all genomes is composed of four related chemicals called nucleic acids: (i) adenine ‘A’, (ii) guanine ’G’, (iii) cytosine ‘C’, and (iv) thymine ‘T’. A sequence of DNA is a string of these nucleic acids (also called “bases” or “base pairs”). These bases connect in a specific way: ‘A’ always pairs with ‘T’, and ‘C’ always pairs with ‘G’. The letters represent the “alphabet” scientists use to write genetic code. The principal biological function of a base is to bond nucleic acids together. Nucleic acids are complex organic substances present in living cells, especially DNA or RNA. There are some 24,000 genes in the human genome, which are bundled into 23 pairs of chromosomes all coiled up in the nucleus of every one of your cells. There are about 37trn cells in the human body. Only about 1.5% of your genetic code, or genome, is made up of your genes. Another 10% regulates your genes to ensure that they turn on and off in the right cells at the right time.

The November 2017 Protein and Cell study

In the April 2015 edition of the journal Protein and Cell, scientists led by Junjiu Huang from Sun Yat-sen University in Guangzhou, China, reported research where he and his colleagues used CRISPR Cas-9 to correct abnormal β-thalassemia genes in human embryos without much success. Researchers suggested, “our work highlights the pressing need to further improve the fidelity and specificity of the CRISPR Cas-9 platform, a prerequisite for any clinical applications of CRISPR Cas-9-mediated editing”. In the November 2017 edition of Protein and Cell Huang and colleagues demonstrated that they had enhanced the fidelity of CRISPR and used the new base editing technique for the first time in human embryos to repair a faulty gene that gives rise to β-thalassemia. They suggested that, “their study demonstrated the feasibility of curing genetic disease in human somatic cells and embryos by a base editor system”.

Β-thalassemia

Β-thalassemia is a serious blood disorder, common in China and southeast Asia, which can be caused by a single mutation in the DNA code. The disorder reduces the production of haemoglobin, which is an iron-containing protein in red blood cells that carries oxygen to cells throughout the body. Without treatment, patients with a severe type of β-thalassemia, usually die before age 5. Correcting this mutation in human embryos may cure people with the disorder and also prevent the disease being passed on to future generations.

Innovative approach

Humans carry two copies of every gene, and in many cases both versions have to be “healthy” to avoid disease. Because it is challenging for researchers to find a lot of embryos, which all have a rare double mutation, Huang’s team created a batch of cloned embryos, then took skin cells from patients with β-thalassemia, removed their DNA-containing nuclei, and introduced them into donor eggs that had their own nuclei removed. The eggs then developed into early stage embryos, which carried the β-thalassemia mutation. Despite the study’s success to effectively edit the embryos and repair the mutations it was only about 20% efficient. Huang noted that the base editing technique he and his colleagues used was not uniform across all cells in the embryos, and their endeavours only sometimes repaired one faulty gene instead of 2. This created what is called “mosaic embryos”, which have both normal and mutant cells and result in a patchwork of cells with different genetic make-up and is potentially dangerous.

Huang concluded that more research is required to improve the safety of the study’s base editing approach. Notwithstanding, scientists believe Huang’s research represents a significant advance, and that base editing techniques hold out the potential to treat and prevent a number of serious and debilitating inherited human diseases, which are more common than some people realise. For example, 1 in 25 children are born with some genetic disorder, which includes β-thalassemia, cystic fibrosis, genetic blindness, sickle cell anaemia, muscular dystrophy, and Tay-Sachs disease.

The October 2017 Nature study

In October 2017, David Liu, and colleagues from the Broad Institute published a paper describing their latest and improved base editing research in the journal Nature. Liu's group genetically transformed base pairs at a target position in the genome of living cells with more than 50% efficiency, with virtually no detectable ‘off-target’ effects such as random insertions, deletions, translocations, or other base-to-base conversions. The work of Liu and his team is significant because it, “introduced point mutations more efficiently and cleanly, and with less off-target genome modification than a current Cas-9 nuclease-based method, and can install disease-correcting or disease-suppressing mutations in human cells”. This clears the path for scientists to use base editing to address many more single-letter mutations than was previously possible. “What we’ve developed is a base editor, a molecular machine, that is a programmable, irreversible, efficient, and an extremely clean way to correct mutations in the genome of living cells,” says Liu.

Delivery is the challenge

Notwithstanding, Liu suggests that the status of base editing is like Amazon without UPS, its principal delivery agent, “Creating a machine that makes the genetic change you need to treat a disease is an important step forward, but it’s only one part of what’s needed to treat a patient. We still have to deliver that machine”, says Liu, and further, “We have to test its safety, we have to assess its beneficial effects in animals and patients and weigh them against any side-effects. We need to do many more things. But having the machine is a good start.” Liu is hopeful that base editing of DNA and RNA could be used as complementary approaches for a “broad set of potential therapeutic applications.” He and his colleagues are exploring base editing to fix blood and neurological disorders as well as hereditary deafness and blindness.

The October 2017 Science study and the advantages of editing RNA

In a paper published in the October 2017 edition of the journal Science, Feng Zhang, of the Broad Institute who is one of the original architects of CRISPR, and senior author describes a variant of base editing, which acts on RNA in human cells instead of DNA. RNA acts as a temporary genetic messenger within cells and naturally degrades in the body. This means that editing RNA instead of DNA does not result in a permanent change to a person’s genome, and therefore has significant potential as a tool for both research and disease treatment. Zhang’s base editing technique makes a temporary correction of a disease-causing mutation without permanent alteration to the genome. According to Zhang, editing DNA is, “permanent and very difficult to reverse, which poses a safety concern, while editing RNA is not.” Zhang’s approach is a potentially safer option when it comes to gene-fixing therapeutics, although any treatment using the technique would need to be administered repeatedly. But Zhang believes repetition could be an advantage because it allows for a therapy to be “upgraded” as scientific knowledge increases and provides a better understanding of specific disease states. The system can change single RNA nucleotides in mammalian cells in a programmable and precise fashion and has the ability to reverse disease-causing mutations at the RNA level, as well as other potential therapeutic and basic science applications.

Zhang and colleagues made one RNA-editing enzyme into a programmable gene-editing tool. “There are 12 possible base changes you can do,” says Omar Abudayyeh, a researcher at the Broad Institute and one of the paper’s authors. Having edited one, “we’re now thinking about the ways to do the other eleven.” By operating on RNA, Zhang and his colleagues avoid ‘off-target’ effects. “With RNA, you have to think about ‘off-targets’ a little differently.” says Abudayyeh. “If some of the RNA gets edited incorrectly the cell will have at least some amount of the right protein. If things go really wrong, the edit is reversible. You can always remove the system and the RNA will eventually degrade and recycle and revert back to normal,” says Abudayyeh. Liu and his team call their new creation REPAIR. They tested it on human cells growing in dishes and edited up to about 27% of the RNAs of two genes. The researchers did not find any ’off-target’ effects and suggest, “REPAIR presents a promising RNA editing platform with broad applicability for research, therapeutics, and biotechnology.”

Delivery challenges

Liu and other medical researchers have stressed the significant challenges associated with delivering CRISPR technologies, which have yet to be resolved before gene editing techniques become viable therapies. The conundrum researchers face is that your body’s biological barriers, which protect you from diseases are the same barriers that create significant obstacles for the delivery of genetic editors. Let us explain. Your DNA is like Fort Knox gold in that it is extremely well protected. For a harmful agent to access your DNA it first has to get under your skin and into your bloodstream. It then has to travel through your bloodstream without being detected by your immune system, which is comprised of networks of cells, tissues, and organs that work together to protect your body. One of the important cells involved in your immune system are white blood cells, also called leukocytes, which come in two basic types that combine to seek out and destroy disease-causing agents. Assuming the harmful agent successfully gets past all these biological barriers, it then has to penetrate your cell membrane and find a way to the nucleus of the cell. These biological defences help to keep you healthy by preventing harmful agents penetrating and transforming your cells into disease-making entities. But, they are the same obstacles that prevent scientists getting gene editors to the right place at the right time in the right quantity. Although delivery technologies are improving, Crispr Therapeutics, Editas Medicine, and Intellia Therapeutics, as well as, Casebia are all investing in delivery mechanisms, which remain significant challenges to overcome before gene editing becomes a regular therapy. This is not only a concern for private companies, but also for the public sector. In January 2018 the US National Institutes of Health announced it will be awarding US$190m in research grants over the next six years, in part to “remove barriers that slow the adoption of genome editing for treating patients”.

Takeaways

Researchers have made substantial scientific advances in embryo gene editing technologies, which have significant potential for next-generation therapeutics. Base editing, described in this Commentary, is one advance, which has the potential to provide effective therapies for a range of disorders known to be caused by the mutation of a single letter in a gene, which currently have either little or no means of a cure. This is important because about 66% of genetic illnesses in humans involve mutations where there is a change in a single letter (or base). Notwithstanding, before such technologies become regular therapies in clinics there are major technical challenges, which need to be overcome in the delivery mechanism for these gene editors.

expand

view in full page

7 years, 6 months ago

34243
0
Facebook

Twitter

Google+

LinkedIn

Report

The global competition to translate genomic data into personal medical therapies - PART 2

HealthPad

Directory:

Cancer

Tags:

cancer genomics

commentary

genetic modifications

personalised medicine

Many people still view China as a ‘copycat’ economy, but this is rapidly changing
China is:
- Pursuing a multi-billion dollar-15 year strategy to become a world leader in genomic engineering and personalized medicine
- Systematically upgrading and incentivizing its large and growing pool of scientists who are making important breakthroughs in the life sciences
- Empowering and encouraging state owned and private life science companies to own and control the capacity to transform genomic, clinical and personal data into personalized medicines

The difference in national approaches to individualism and privacy confers an added competitive advantage to China and its life science ambitions
China’s approach to individualism and privacy issues could have implications for society

The global competition to translate genomic data into personal medical therapies

PART 2

China is no longer a low cost ‘copycat’ economy. Indeed, it has bold plans to become a preeminent global force in genomic engineering to prevent and manage devastating and costly diseases. Here we briefly describe aspects of China’s multibillion-dollar, government-backed initiative, to own and control significant capacity to transform genomic data into precision medicines. This is not only a ‘numbers’ game. China’s drive to achieve its life science ambitions is also advantaged by a different approach to ‘individualism’ and privacy compared to that of the US; and this could have far-reaching implications for future civilizations.

Uneven playing field
Genomic engineering and precision medicine have the potential to revolutionize how we prevent and treat intractable diseases. Who owns the intellectual property associated with genomic engineering, and who first exploits it, will reap significant commercial benefits in the future. However, genomic technologies are not like any other. This is because genetically modifying human genomes could trigger genetic changes across future generations. Misuse of such technologies therefore could result in serious harm for individuals and their families. On the other hand, over regulation of genomic engineering could slow or even derail the prevention and treatment of devastating and costly diseases. Establishing a balance, which supports measures to mitigate misuse of genomic technologies while allowing the advancement of precision medicine is critical. However, this has proven difficult to establish internationally.

Chinese scientists have crossed an ethical line
Chinese culture interprets individualism and privacy differently to American culture, and therefore China responds differently to certain ethical standards compared to the US and some other Western nations. Indeed, national differences were ignited in 2012 when Chinese researchers published their findings of the world’s first endeavors to modify the genomes of human embryos to confer genetic resistance to certain diseases. Because such modifications are heritable critics argued that the Chinese scientists crossed a significant ethical line, and this was the start of a “slippery slope”, which 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 human beings.

International code of conduct called for but not adhered to
2 prominent scientific journals, Nature and Science, rejected the Chinese research papers reporting world-first scientific breakthroughs on ethical grounds. 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. 40 countries have banned genetically modifying human embryos. In 2016, a report from the UK’s Nuffield Council on Bioethics stressed the importance of an internationally agreed ethical code of conduct before genomic engineering develops further.

In 2017 an influential US science advisory group formed by the National Academy of Sciences and the National Academy of Medicine gave ‘lukewarm’ support to the modification of human embryos to prevent, “serious diseases and disabilities” in cases only where there are no other “reasonable alternatives”. The French oppose genomic modification, the Dutch and the Swedes support it, and a recent Nature editorial suggested that the EU is, “habitually paralyzed whenever genetic modification is discussed”. In the meantime, clinical studies, which involve genomic engineering, are advancing at a pace in China.

With regard to genome testing, western human rights activists have warned that China is targeting vulnerable groups and minorities to help build vast genomic databases without appropriate protection for individuals. Those include migrant workers, political dissidents and ethnic or religious minorities such as the Muslim Uighurs in China's far western Xinjiang region. Xinjiang authorities are reported to have invested some US$10bn in advanced sequencing equipment to enhance the collection and indexing of these data.

Different national interpretations of ‘individualism’
‘Individualism’, which is at the core of ethical considerations of genomic engineering, is challenging to define because of its different cultural, political and social interpretations. For example, following the French Revolution, individualisme was used pejoratively in France to signify the sources of social dissolution and anarchy, and the elevation of individual interests above those of the collective. The contemporary Chinese interpretation of individualism is similar to the early 19^th century French interpretation. It does not stress a person’s uniqueness and separation from the State, but emphasizes an individual’s social; contract and harmony with the State. By contrast, American individualism is perceived as an inalienable natural right of all citizens, and independent of the State.

Further, American individuals are actively encouraged to challenge and influence the government and its regulatory bodies, whereas in China citizens are expected to unquestionably support the State. China is a one party state, where individuals generally accept that their government and its leaders represent their higher interests, and most citizens therefore accept the fact that they are not expected to challenge and influence policies determined by the State and its leaders. This difference provides China with a significant competitive advantage in its endeavors to become a world leader in the life sciences,

Human capital

By 2025, some 2bn human genomes could be sequenced. This not only presents ethical challenges, but also significant human capital challenges. The development of personalized medicines is predicated upon the ability to aggregate and process vast amounts of individual genomic, physiological, health, environmental and lifestyle data. This requires next generation sequencing technologies, smart AI systems, and advanced data managers of which there is a global shortage. Thus, the cultivation and recruitment of appropriate human capital is central to competing within the rapidly evolving international genomic engineering marketplace. The fact that China has a more efficacious strategy to achieve this than the US and other Western democracies provides it with another significant competitive advantage.

STEM graduates
Since the turn of the century, China has been engaged in a silent revolution to substantially increase its pool of graduates in science, technology, engineering and mathematics (STEM), while the pool of such graduates in the US and other Western democracies has been shrinking. In 2016, China was building the equivalent of almost one university a week, which has resulted in a significant shift in the world's population of STEM graduates. According to the World Economic Forum, in 2016, the number of people graduating in China and India were respectively 4.7m and 2.6m, while in the US only 568,000 graduated. In 2013, 40% of all Chinese graduates finished a degree in STEM, over twice the share of that in US universities. In 2016, India had the most graduates of any country worldwide with 78m, China followed closely with 77.7m, and the US came third with 67m graduates.

University education thriving in China and struggling in the West
In addition to China being ahead of both the US and Europe in producing STEM graduates; the gap behind the top 2 countries and the US is widening. Projections suggest that by 2030 the number of 25 to 34-year-old graduates in China will increase by a further 300%, compared with an expected rise of around 30% in the US and Europe. In the US students have been struggling to afford university fees, and most European countries have put a brake on expanding their universities by either not making public investments or restricting universities to raise money themselves.

The increasing impact of Chinese life sciences
China's rapid expansion in STEM graduates suggests that the future might be different to the past. Today, China has more graduate researchers than any other country, and it is rapidly catching up with the US in the number of scientific papers published. The first published papers to describe genetic modifications of human embryos came from Chinese scientists.

Further, according to the World Intellectual Property Organization, domestic patent applications inside China have soared from zero at the start of the 21^st century to some 928,000 in 2014: 40% more than the US’s 579,000, and almost 3 times that of Japan’s 326,000.

China’s strategy to reverse the brain drain
Complementing China’s prioritization of domestic STEM education is its “Qianren Jihua” (Thousand Talents) strategy. This, established in the wake of the 2008 global financial crisis to reverse China’s brain drain, trawls the world to seek and attract highly skilled human capital to China by offering them incentives. Qianren Jihua’s objective is to encourage STEM qualified Chinese ex patriots to return to China, and encourage those who already reside in China to stay, and together help create an internationally competitive university sector by increasing the production of world-class research to support China’s plans to dominate precision medicine and life sciences.

Government commitment

In 2016, China announced plans for a multi-billion dollar project to enhance its competitiveness by becoming a global leader in molecular science and genomics. China is committed to supporting at least three principal institutions, including the Beijing Genomics Institute (BGI), to sequence the genomes of many millions.

In addition to investments at home, China also is investing in centers similar to that of BGI abroad. Over the past 2 years China has invested more than US$110bn on technology M&A deals, which it justifies by suggesting that emerging technologies are, “the main battlefields of the economy”. Early in 2017 BGI announced the launch of a US Innovation Center, co-located in Seattle and San Jose. The Seattle organization is focused on precision medicine and includes collaborations with the University of Washington, the Allen Institute for Brain Science, and the Bill and Melinda Gates Foundation. The San Jose facility, where BGI already has a laboratory employing over 100, supports its ambitions to develop next-generation sequencing technologies, which until now have been dominated by the US sequencing company Illumina.

Changing structure of China’s economy
Some suggest that China’s rise on the world life sciences stage will be short lived because the nation is in the midst of a challenging transition to a slower-growing, consumption-driven economy, and therefore will not be able to sustain such levels of investment; and this will dent its ambition to become a global player in genomic science. An alternative argument suggests slower growth forces China to act smarter, and this is what drives its precision medicine ambitions.

Between 1985 and 2015, China’s annual GDP rose, on average, by 9.4%. Fuelling this growth was a steady supply of workers entering the labour force and massive government led infrastructure investments. Now, because of China’s ageing population, its labour capacity has peaked and started to decline. Without labour force expansion, and investment constrained by debt, China is obliged to rely more heavily on innovation to improve its productivity. And this drives, rather than slows, China’s strategy to become a world leader in genomic technologies and personalized medicine.

China’s economic growth is slowing, but its production of scientific research is growing
Although China’s economy is slowing, it is still comparatively large. In 2000, China spent as much on R&D as France; now it invests more in genomics than the EU, when adjusted for the purchasing power of its currency. Today, China produces more research articles than any other nation, apart from the US, and its authors’ feature on around 20% of the world’s most-cited peer reviewed papers. Top Chinese scientific institutions are breaking into lists of the world’s best, and the nation has created some unparalleled research facilities. Even now, every 16 weeks China produces a Greece-size economy, and doubles the entire size of its economy every 7 years. Today, China has an economy similar in size to that of the US, and most projections suggest that, over the next 2 decades, China’s economy will dwarf that of the US.

Takeaways

China is cloning its successful strategy to own and control significant mineral and mining rights to the life sciences. Over the past 20 years China has actively pursued mining deals in different global geographies, and now controls significant mining rights and mineral assets in Africa and a few other countries. This allows China to affect the aggregate supply and world market prices of certain natural resources. Now, China is cloning this commercially successful strategy to the life sciences, and has empowered and encouraged a number of state owned and private companies to own and control genomic engineering and precision medicine. China’s single-minded determination to become a world leader in life sciences, and its interpretation of individualism and privacy issues could have far reaching implications for the future of humanity.

expand

view in full page

7 years, 6 months ago

37903
0
Facebook

Twitter

Google+

LinkedIn

Report

The global competition to translate genomic data into personal medical therapies - PART 1

HealthPad

Directory:

Cancer

The global competition to translate genomic data into personal medical therapies

PART 1

Professor Dame Sally Davies, England’s Chief Medical Officer, is right. (Genomics) “has the potential to change medicine forever. . . . The age of precision medicine is now, and the NHS must act fast to keep its place at the forefront of global science.”

It is doubtful whether the UK will be able to maintain its place as a global frontrunner in genomics and personalized medicine. It is even doubtful whether the US, the first nation to discover the genome, and which became preeminent in genomic research, will be able to maintain its position. China, with its well-funded strategy to become the world’s leader in genomics and targeted therapies, is likely to usurp the UK and the US in the next decade.

This Commentary is in 2 parts. Part 1 provides a brief description of the global scientific competition between nation states to turn genomic data into medical benefits. China’s rise, which is described, could have significant implications for the future ownership of medical innovations, data protection, and bio-security. Part 2, which follows in 2 weeks, describes some of the ethical, privacy, human capital and economic challenges associated with transforming genomic data into effective personal therapies.

Turning genomic data into medical benefits

Turning genomic data into medical benefits is very demanding. It requires a committed government willing and able to spend billions, a deep understanding of the relationship between genes and physiological traits, next generation sequencing technologies, artificial intelligence (AI) systems to identify patterns in petabytes (1 petabyte is equivalent to 1m gigabytes) of complex data, world-class bio-informaticians, who are in short supply; comprehensive and sophisticated bio depositories, a living bio bank, a secure data center, digitization synthesis and editing platforms, and petabytes of both genomic, clinical, and personal data. Before describing how the UK, US and China are endeavoring to transform genomic data into personal medicine, let us refresh our understanding of genomics.

Genomics, the Human Genomic Project and epigenetics

It is widely understood that your genes are responsible for passing specific features or diseases from one generation to the next via DNA, and genetics is the study of the way this is done. However, it is less widely known that your genes are influenced by environmental and other factors. Scientists have demonstrated that inherited genes are not static, and lifestyles and environmental factors can precipitate a chemical reaction within your body that could permanently alter the way your genes react. This environmentally triggered gene expression, or epigenetic imprint, can be bad, such as a disease; or good, such as a tolerant predisposition. Epigenetics is still developing as an area of research, but it has demonstrated that preventing and managing disease is as much to do with lifestyles and the environment, as it is to do with inherited genes and drugs. If environmental exposure can trigger a chemical change in your genes that results in the onset of disease, then scientists might be able to pharmacologically manipulate the same mechanisms in order to reverse the disease.

DNA is constantly subject to mutations, which can lead to missing or malformed proteins, and that can lead to disease. You all start your lives with some mutations, which are inherited from your parents, and are called germ-line mutations. However, you can also acquire mutations during your lifetime. Some happen during cell division, when DNA gets duplicated, other mutations are caused when environmental factors including, UV radiation, chemicals, and viruses damage DNA.

You have a complete set of genes in almost every healthy cell in your body. One set of all these genes, (plus the DNA between them), is called a genome. The genome is the collection of 20,000 genes, including 3.2bn letters of DNA, which make up an individual. We all share about 99.8% of the genome. The secrets of your individuality, and also of the diseases you are prone to, lie in the other 0.2%, which is about 3 or 4m letters of DNA. The genome is known as ‘the blueprint’ of life’, and genomics is the study of the whole genome, and how it works. Whole genome sequencing (WGS) is the process of determining the complete DNA sequence of an organism's genome at a point in time.

‘The Human Genome Project’ officially began in 1990 as an international research effort to determine a complete and accurate sequence of the 3bn DNA base pairs, which make up the human genome, and to find all of the estimated 20 to 25,000 human genes. The project was completed in April 2003. This first sequencing of the human genome took 13 years and cost some US$3bn. Today, it takes a couple of days to sequence a genome, and costs range from US$260 for targeted sequencing to some US$4,000 for WGS. Despite the rapidly improving capacity to read, sequence and edit the information contained in the human genome, we still do not understand most of the genome’s functions and how they impact our physiology and health.

Roger Kornberg explains the importance of genomics

Roger Kornberg, Professor of Structural Biology at Stanford University, and 2006 Nobel Laureate for Chemistry, explains the significance of sequencing the human genome, “The determination of the human genome sequence and the associated activity called genomics; and the purposes for which they may be put for medical uses, takes several forms. The knowledge of the sequence enables us to identify every component of the body responsible for all of the processes of life. In particular, to identify any component that is either defective or whose activity we may adjust to address a problem or a condition. So the human genome sequence makes available to us the entire array of potential targets for drug development. . . . . The second way in which the sequence and the associated science of genomics play an important role is in regard to individual variations. Not every human genome sequence is the same. There is a wide variation, which in the first instance is manifest in our different appearances and capabilities. But it goes far deeper because it is also reflected in our different responses to invasion by microorganisms, to the development of cancer and to our susceptibility to disease in general. It will ultimately be possible, by analyzing individual genome sequences to construct a profile of such susceptibilities for every individual, a profile of the response to pharmaceuticals for every individual, and thus to tailor medicines to the needs of individuals.” See video below.

UK’s endeavors to transform genomic data into personal therapies

In 2013 the UK government set up Genomics England, a company charged with sequencing 100,000 whole genomes by 2017. In 2014, the government announced a £78m deal with Illumina, a US sequencing company, to provide Genomics England with next generation whole genome sequencing services. At the same time the Wellcome Trust invested £27m in a state-of-the-art sequencing hub to enable Genomics England to become part of the Wellcome Trust’s Genome Campus in Hinxton, near Cambridge, England. In 2015, the UK government pledged £215m to Genomics England.

DNA testing and cancer
“DNA sequencing is simply the process of reading the code that is in any organism . . . It’s essentially a technology that allows us to extract DNA from a cell, or many cells, pass it through a sophisticated machine and read out the sequence for that organism or individual,” says David Bowtell, Professor and Head of the Cancer Genomics and Genetics Program at the Peter MacCallum Cancer Centre, Melbourne, Australia; see video below. “DNA testing has becomeincreasingly widespread because advances in technology have made the opportunity to sequence the DNA of individuals affordable and rapid . . . DNA testing in the context of cancer can be useful to identify a genetic risk of cancer, and to help clinicians make therapeutic decisions for someone who has cancer,” says Bowtell, see video below.

What is DNA sequencing?

What are the advanteges of a person having a DNA test?

Need for National Genome Board
Despite significant investments by the UK government, Professor Davies, England’s Chief Medical Officer, complained in her 2017 Annual Report that genomic testing in the UK is like a “cottage industry” and recommended setting up a new National Genome Board tasked with making whole genome sequencing (WGS) standard practice in the NHS across cancer care, as well as some other areas of medicine, within the next 5 years.

USA’s endeavors to transform genomic data into personal therapies

In early 2015 President Obama announced plans to launch a $215m public-private precision medicine initiative, which involved the health records and DNA of 1m people, to leverage advances in genomics with the intention of accelerating biomedical discoveries in the hope of yielding more personalized medical treatments for patients. A White House spokesperson described this as “a game changer that holds the potential to revolutionize how we approach health in the US and around the world.”

Data management challenges
The American plan did not seek to create a single bio-bank, but instead chose a distributive approach that combines data from over 200 large on-going health studies, which together involves some 2m people. The ability of computer systems or software to exchange and make use of information stored in such diverse medical records, and numerous gene databases presents a significant challenge for the US plan. According to Bowtell, “Data sharing is widespread in an ethically appropriate way between research institutions and clinical groups. The main obstacles to more effective sharing of information are the very substantial informatics challenges. Often health systems have their own particular ways of coding information, which are not cross compatible between different jurisdictions. Hospitals are limited in their ability to capture information because it takes time and effort. Often information that could be useful to researchers, and ultimately to patients, is lost, just because the data are not being systematically collected.” See video below.

China’s endeavors to transform genomic data into personal therapies

In 2016, the Chinese government launched a US$9bn-15-year endeavor aimed at turning China into a global scientific leader by harnessing computing and AI technologies for interpreting genomic and health data. This positions China to eclipse similar UK and US initiatives.

Virtuous circle
Transforming genomic data to medical therapies is more than a numbers race. Chinese scientists are gaining access to ever growing amounts of human genomic data, and developing the machine-learning capabilities required to transform these data into sophisticated diagnostics and therapeutics, which are expected to drive the economy of the future. The more genomic data a nation has the better its potential clinical outcomes. The better a nation’s clinical outcomes the more data a nation can collect. The more data a nation collects the more talent a nation attracts. The more talent a nation attracts the better its clinical outcomes.

The Beijing Genomics Institute
In 2010 China became the global leader in DNA sequencing because of one company: the Beijing Genomics Institute (BGI), which was created in 1999 as a non-governmental independent research institute, then affiliated to the Chinese Academy of Sciences, in order to participate in the Human Genome Project as China's representative. In 2010, BGI received US$1.5bn from the China Development Bank, and established branches in the US and Europe. In 2011 BGI employed 4,000 scientists and technicians. While BGI has had a chequered history, today it is one of the world’s most comprehensive and sophisticated bio depositories.

The China National GeneBank
In 2016 BGI-Shenzhen established the China National GeneBank (CNGB) on a 47,500sq.m site. This is the first national gene bank to integrate a large-scale bio-repository and a genomic database, with a goal of enabling breakthroughs in human health research. The gene-bank is supported by BGI’s high-throughput sequencing and bio-informatics capacity, and will not only provide a repository for biological collection, but more importantly, it is expected to develop a novel platform to further understand genomic mechanisms of life. During the first phase of its development the CNGB will have saved more than 10m bio-samples, and have storage capacity for 20 petabytes (20m gigabytes) of data, which are expected to increase to 500 petabytes in the second phase of its development. The CNGB represents the new generation of a genetic resource repository, bioinformatics database, knowledge database and a tool library, “to systematically store, read, understand, write, and apply genetic data,” says Mei Yonghong, its Director.

Whole-genome sequencing for $100
The CNGB could also help to bring down the cost of genomic sequencing. It is currently possible to sequence an individual's entire genome for under US$1,000, but the CNGB aims to reduce the price to US$152. Meanwhile, researchers at Complete Genomics, a US company acquired by BGI in 2013, which has developed and commercialized a DNA sequencing platform for human genome sequencing and analysis, are pushing the technology further to enable whole-genome sequencing for US$100 per sample. China's share of the world's sequencing-capacity is estimated to be between 20% and 30%, which is lower than when BGI was in its heyday, but expected to increase fast. “Sequencing capacity is rising rapidly everywhere, but it's rising more rapidly in China than anywhere else,” says Richard Daly, CEO, DNAnexus, a US company, which supplies cloud platforms for large-scale genomics data.

The intersection of genomics and AI
Making sense of 1m human genomes is a major challenge, says Professor Jian Wang, former BGI President and co-founder, who has started another company called iCarbonX. Also based in Shenzhen, the company is at the intersection of genomics and AI. iCarbonX has raised more than US$600m, and plans to collect genomic data from more than 1m people, and complement these data with other biological information including changes in levels of proteins and metabolites. This is expected to allow iCarbonX to develop a new digital ecosystem, comprised of billions of connections between huge amounts of individuals’ biological, medical, behavioural and psychological data in order to understand how their genes interact and mutate, how diseases and aging manifest themselves in cells over time, how everyday lifestyle choices affect morbidity, and how these personal susceptibilities play a role in a wide range of treatments.

iCarbonX is expected to gather data from brain imaging, biosensors, and smart toilets, which will allow real-time monitoring of urine and faeces. The Company’s goal is to be able to study the evolution of our genome as we age and design personalized health predictions such as susceptibilities to diseases and tailored treatment options. iCarbonX’s endeavours are expected to dwarf efforts by other US Internet giants at the intersection of genomics and AI.

Ethical challenges

China’s single-minded objective to turn its knowhow and experience of genome sequencing into personal targeted medical therapies has made it a significant global competitive force in life sciences. However, precision medicine’s potential to revolutionize advances in how we treat diseases confers on it moral and ethical obligations. For personal therapies to be effective, it is important that genomic data are complemented with clinical and other personal data. This combination of data is as personal as personal information gets. There could be potential harm to the tested individual and family if genomic information from testing is misused. Reconciling therapy and privacy is important, because privacy issues concerning patients' genomic data can slow or derail the progression of novel personal therapies to prevent and manage intractable diseases. The stakes are high in terms of biosecurity, as genomic research is both therapeutic and a strategic element of national security. While it is crucial to leverage genomic data for future health, economic and biodefense capital, these data will also have to be appropriately managed and protected. Part 2 of this Commentary dives into these challenges a little deeper, and describes some of China’s competitive advantages in the race to become the world’s preeminent nation in genomics and precision medicine.

Takeaways

Despite the endeavours of the UK and US to remain at the forefront of the international competition to transform genomic data into personalized medical therapies for some of the worlds most common and intractable diseases, it seems reasonable to assume that China is on the cusp of becoming the most dominant nation in novel personalized treatments. Notwithstanding, China’s determination to assume the global frontrunner position in genomic science might have blunted its concerns for some of the ethical issues, which surround the life sciences. To the extent that this might be the case the future of humanity might well differ significantly from the generally accepted western vision.

expand

view in full page

8 years ago

41031
0
Facebook

Twitter

Google+

LinkedIn

Report

Gene editing battles

HealthPad

Directory:

Medical Technology

Tags:

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 14^th 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 15^th 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.

Takeaways

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.

expand

view in full page

8 years, 1 month ago

32804
0
Facebook

Twitter

Google+

LinkedIn

Report

Gene editing positioned to revolutionise medicine

HealthPad

Directory:

Medical Technology

Tags:

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.

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.

Takeaways

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.

expand

view in full page