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  • 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 17th 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 Actwhich 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.
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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 Addgenea 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 Medicineresearchers 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 CenterUniversity 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 19th and the beginning of the 20th 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 11th 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 21st century version of Galtonism.
 
The genie is truly out of the bottle.
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  • A 2018 clinical study in China is the first to use CRISPR to edit cells inside the human body in an attempt to eliminate the human papilloma virus (HPV) and is hugely significant for millions of women
  • Nearly all sexually active people get an HPV virus at some point in their lives and persistent high-risk HPV infections are the main cause of cervical cancer
  • Respectively 34,800 and 256,000 women in the UK and US live with cervical cancer and each year about 3,200 and 12,200 new cases of cervical cancer are diagnosed in the UK and US respectively nearly all related to HPV
  • Cervical cancer is increasing in older women not eligible for the HPV vaccine and not availing themselves of Pap test screening programs
  • A new study suggests that cervical cancer mortality among older women could increase by 150% in the next 20 years

CRISPR positioned to eliminate human papilloma viruses that cause cervical cancer

January 2018 marked the beginning of the first CRISPR clinical study to attempt to edit cells while they are in the body of women in the hope to eliminate the human papilloma virus (HPV), which is the main cause of cervical cancer. The study, led by Zheng Hu of the First Affiliated Hospital, Sun Yat-Sen University, Guangzhou, Guangdong, China, is the first to edit human cells while inside the body. Zheng Hu will apply a gel that carries the necessary DNA coding for the CRISPR machinery to the cervixes of 60 women between the ages of 18 and 50. The study’s aim is to prevent cervical cancers by targeting and destroying the HPV genes that cause tumor growth while leaving the DNA of normal cells untouched. Current estimates suggest that every year 527,624 women are diagnosed with cervical cancer and 265,672 die from the disease. Zheng Hu’s study is expected to be completed by November 2018 and findings reported in January 2019.
 
In this Commentary

This Commentary describes the Chinese CRISPR study and the etiology and epidemiology of cervical cancer. It also describes the current cervical cancer vaccination possibilities and the challenges they face. Further, the significance of the Chinese study is demonstrated by an English study, published in December 2017 in the Lancet Public Health, which warns that although HPV vaccination programs have significantly reduced the incidence of cervical cancer among young women, the incidence of the disease is increasing significantly among older women who do not qualify for the cervical cancer vaccine, and fail to avail themselves of regular Pap tests (A Pap test is a simple, quick and essentially painless screening procedure for cancer or precancer of the uterine cervix). The latter part of the Commentary describes advances that CRISPR technology has made over the past decade as well as describing its main ethical and technical challenges.
 
Human papilloma virus (HPV)

There are over 200 different types of HPV related viruses. Viruses are the etiological agents of approximately 15% of human cancers worldwide, and high-risk HPVs are responsible for nearly 5% of cancers worldwide. It is estimated that about 75% of the reproductive-age population has been infected with 1 or 2 types of genital HPV. About 79m Americans are currently infected with HPV, and about 14m people become newly infected each year. The American Centers for Disease Control and Prevention estimates that more than 90 and 80% of sexually active American men and women respectively will be infected with at least one type of HPV at some point in their lives. Most HPV infections are harmless, they last no more than 1 to 2 years, and usually the body clears the infections on its own. More than 40 HPV types can be easily spread by anal, oral and vaginal sex. About 12 HPV types are high risk, and it is estimated these persist in only about 1% of women. However, a central component of the association between HPV and cervical carcinogenesis is the ability of HPV to persist in the lower genital tract for long periods without being cleared. These persistent high-risk types of HPV can lead to cell changes, which if untreated, may progress to cancer. Other HPV types are responsible for genital warts, which are not sexually transmitted.
 
Etiology of cervical cancer
 
 “The way that the HPV causes cancer informs us about how cancer occurs in other settings. Virus particles insert foreign DNA into a person’s normal cells. This virus then turns off the “off-switch” and allows the oncogenes [Genes that can transform a cell into a tumor cell] to progress unchecked and create an oncogenic virus. So, in this case the 'insult' is known: it’s an HPV virus. However, in many circumstances we’re not sure what that initial switch is that upsets the balance between a tumor suppressor and an oncogene,” says Whitfield Growdon, of the Massachusetts General Hospital and Professor of Obstetrics, Gynecology and Reproductive Biology at the Harvard University Medical School: see video below:

 
 
HPV and cervical cancer

The association of risk with sexual behavior has been suggested since the mid-19th century, but the central causal role of HPV infection was identified just 40 years ago. HPV infection is the main etiologic agent of cervical cancer. 99% of cervical cancer cases are linked to genital infection with HPV and it is the most common viral infection of the reproductive tract. HPV types 16 and 18 are responsible for about 70% of all cervical cancer cases worldwide. Further, there is growing evidence to suggest that HPV also is a relevant factor in other anogenital cancers (anus, penis, vagina and vulva) as well as head and neck cancers. The importance of prevention and cervical cytological screening was established in the second half of the 20th century, which preceded and even advanced etiologic understanding.
 
Epidemiology of cervical cancer
 
Cervical cancer is one of the most common types of gynecological malignancies worldwide. It ranks as the 4th most frequent cancer among women in the World, and the 2nd most common female cancer in women between 15 and 44. According to the World Health Organization there were some 630m cases of HPV infections in 2012, and 190m of these led to over 0.5m new diagnoses of cervical cancer. The World has a population of some 2,784m women aged 15 and older who are at risk of developing cervical cancer. Each year about 3,200 and 12,200 new cases of cervical cancer are diagnosed in the UK and US respectively; nearly all related to HPV. There is estimated to be 34,800 and 256,000 women in the UK and US respectively living with cervical cancer. Each year some 890 and 4,200 women die from cervical in the UK and US respectively.
 
HPV vaccines
 
HPV vaccines, which prevent certain types of HPV infections, are now available to females up to the age of 26, and have the potential to reduce the incidence of cervical and other anogenital cancers. “Vaccinations work by using your own immune system against foreign pathogens such as viruses and bacteria. Vaccination against some high risk sub-types of cancer-causing HPV viruses is one of the most meaningful interventions we’ve had since the development of the Pap test,” says Growdon: see video below.

 
 
Gardasil and Cervarix

Gardasil, an HPV vaccine developed by Merck & Co., and licenced by the US Food and Drug Administration (FDA) in 2006, was the first HPV vaccine recommended for girls before their 15th birthday, and can also be used for boys. In 2008 Cervarix, an HPV vaccine manufactured by GlaxoSmithKline,  was introduced into the UK’s national immunization program for girls between 12 and 13. Both vaccines have very high efficacy and are equally effective to immunise against HPV types 16 and 18, which are estimated to cause 70% of cervical cancer cases. Both vaccines significantly improve the outlook for cervical cancer among women living in countries where it is routinely administered to girls before they become sexually active. “Both Gardasil and Cervarix vaccines have been shown to be incredibly effective at preventing the development of high-grade dysplasia, which we know, if left unchecked, would turn into cervical cancer,” says Growdon: see video above.

Gardasil also protects against HPV types 6 and 11, which can cause genital warts in both men and women. Second-generation vaccines are under development to broaden protection against HPV. In 2014 the FDA approved Gardasil 9, an enhanced vaccine, which adds protection against an additional 5 HPV types that cause approximately 20% of cervical cancers.
Global challenge

Despite the availability of prophylactic vaccines, HPVs remain a major global health challenge due to inadequate vaccine availability and vaccination coverage. Despite the promise, vaccine uptake has been variable in developed nations, and limited in developing nations, which are most in need. The available vaccines are expensive, require a cold chain to protect their quality, and are administered in 2 to 3 doses spanning several months. Thus, for a variety of practical and societal reasons (e.g., opposition to vaccination of young girls against a sexually transmitted agent, fear of vaccination), coverage, particularly in the US has been lower than would be optimal from a public health perspective.
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Gene editing battles


Success among young women

Notwithstanding, a study referred to above and published in the Lancet Public Health suggests cervical cancer cases are expected to fall by 75% among young women for whom vaccination is now the norm. Death from cervical cancer among the generation who were 17 or younger in 2008 when the UK vaccination program was introduced is expected to virtually disappear.
 
Challenges for older women

Notwithstanding the success of HPV vaccines for young women, there are continuing challenges for older women who, because of their age, do not qualify for HPV vaccines, and do not attend their Pap screening test when invited. “Pap tests involve scraping the cervix on the outside for cells, which then udergo microscopic examination. Today this is carried out by a computer. Further examination is carried out by a cytopathologist who determines status . . . . . . . . . . Pap tests do not diagnose cancer, but tell you whether you are at high risk of either having pre-cancerous or cancerous cells. Actual diagnosis of cervical cancer involves a colposcopy. This is a simple procedure, which uses a specific type of microscope called a colposcope to look directly into the cervix, magnify its appearance, and helps to take biopsies of abnormal areas,” says Growdon: see videos below.
 

What is a Pap smear test?


Diagnostic tests for cervical cancer
 
Older women and Pap tests

Pap tests, which are offered by NHS England to women between 25 and 64, is the most effective way of preventing cervical cancer; yet data show that in 2016 there was a significant drop in Pap test screening as women’s age increased. If such screening covered 85% of women, it is estimated that it would reduce deaths from cervical cancer by 27% in 5 years, and the diagnosis of new cases of cervical cancer by 14% in 1 year. According to the authors of the 2017 Lancet study, “The risk of acquiring an HPV infection that will progress to cancer has increased in unvaccinated individuals born since 1960, suggesting that current screening coverage is not sufficient to maintain – much less reduce – cervical cancer incidence in the next 20 years.”
 
Cervical cancer projected to increase in older women

Over the next 2 decades, diagnoses of cervical cancer in women between 50 and 64 are projected to increase by 62%, which could increase mortality from the disease by nearly 150%. “The main reason for this is that the population is ageing and women currently 25-40 will not benefit from vaccination – and they are in the age range where the likelihood of getting an HPV infection is quite high,” saidAlejandra Castanon one of the authors of the Lancet study.
 
Chinese study extends CRISPR technology

The Chinese study mentioned above to eliminate the HPV virus employs an innovative extension of CRISPR, which is a ‘game-changing’ technology. Over the past decade CRISPR has become a significant tool for genetic manipulation in biomedical research and biotechnology.  
 
CRISPR and genome editing

CRISPR is a complex system that can recognize and cut DNA sequences in order to provide organisms a strong defence against attacks and make them immune from further assaults. CRISPR has been adapted for both in vitro and in vivo use in eukaryotic cells to perform highly selective gene silencing or editing. Eukaryotic cells are those that contain a nucleus surrounded by a membrane and whose DNA is bound together by proteins into chromosomes.  CRISPRs are specialized stretches of DNA, and "CRISPR-Cas9" provides a powerful tool for precision editing due to its highly efficient targeting of specific DNA sequences in a genome, and has become the standard for genetic editing. Cas9 protein is an enzyme that acts like a pair of molecular scissors capable of cutting strands of DNA. The genomes of organisms encode messages and instructions within their DNA sequences. Genome editing involves changing those sequences, thereby changing the messages. This is achieved by making a break in the DNA, and tricking a cell's natural DNA repair mechanisms to make desired changes; CRISPR-Cas9 provides a means to do this. The technology’s ease of use and low cost have made it popular among the scientific community, and the possibility of its use as a clinical treatment in several genetically derived pathologies has rapidly spread its significance worldwide.
 
Changing ethical concerns

Despite CRISPRS promise there have been significant ethical concerns to genome editing, which center around human germline editing. This is because germline editing entails deliberately changing the genes passed on to children and future generations; in other words, creating genetically modified people. The debate about genome editing is not a new one, but has regained attention following the discovery that CRISPR has the potential to make such editing more accurate and even "easy" in comparison to older technologies. As of 2014, there were about 40 countries that discouraged or banned research on germline editing, including 15 nations in Western Europe. There is also an international effort, launched in December 2015 at the International Summit on Human Gene Editing and led by the US, UK, and China, to harmonize regulation of the application of genome editing technologies. 
 
After initially being opposed to using CRISPR in humans, in June 2016, the US National Institutes of Health advisory panel approved the technology for a study designed to target three types of cancer and funded by the Parker Institute for Cancer Immunotherapy at the University of Pennsylvania. In 2017 the UK approved the use of CRISPR for research in healthy human embryos. 

 
Off-target effects

Soon after scientists reported that CRISPR can edit DNA in 2012, experts raised concerns about “off-target effects,” meaning either CRISPR changes a gene scientist did not want changed or it fails to change a gene that they do. Although CRISPR-Cas9 is known for its precision a study, published in 2017 in the journal Nature Methods, raised concerns that because of the potential for “off-target effects” testing CRISPR in humans may be premature. Non-intended consequenes can happen because one molecule in the CRISPR system acts like a “molecular bloodhound”, searching the genome until it finds a match to its own sequence of  genetic letters; but there are 6bn genetic letters of the human genome, which suggests that there may be more than one match. Scientists anticipate and plan for this by using a computer algorithm to predict where such flaws might occur, then they search those areas to see if such off-target effects did occur. Notwithstanding such procedures and despite CRISPR’s precision, substantial efforts still are required to make the technology a common device safe for human clinical treatments.
 
Advances using CRISPR
 
The first clinical study using CRISPR began in October 2016 at the West China Hospital in Chengdu. Researchers, led by oncologist Lu You from Sichuan University, removed immune cells from the blood of a person with lung cancer, used CRISPR to disable a gene called PD-1, and then returned the cells to the body. This study is part of a much larger CRISPR genome editing revolution. Today, there are about 20 human clinical studies taking place using CRISPR technology most of which are in China. Different studies focus on different cancers including, breast, bladder, oesophageal, kidney, and prostate cancers. Further, a 2017 paper published in the journal Cell describes a number of innovative ways CRISPR being used; including editing cells while inside the body.
 
Takeaways
 
Despite the efficacy of HPV vaccines, immunization against cervical cancer still has significant challenges. Vaccines only target young people before they become sexually active, and are not recommended for slightly older and sexually active women. There is an urgent and growing concern about older women therefore who were not eligible for HPV vaccination, and are not availing themselves of regular Pap tests, and in whom the incidence of cervical cancer is increasing significantly. This makes Zheng Hu’s clinical study extremely important because it holds out the potential to substantially dent this large and rapidly increasing burden of cervical cancer.
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