We all focused on one topic throughout 2020: Covid-19. No single day passed without news on the pandemic as we counted numbers of positive cases and the death toll while anticipating for a vaccine. In the meantime, we got more familiar with some of the medical processes, like phases, clinical trials, mutations, etc. for all this had to deal with the most precious gift we are given: life.

In our last issue, we touched upon the history of pharmacology and how modern-day drugs are made in an article titled “Pharmacology: The Journey of a Chemical Compound into a Drug.” Now, we will explore the multiple, lengthy phases of clinical trials that drugs must undergo and why they are imperative in order for new medicines to get approved for the marketplace.

Clinical trials are a way to test new methods of diagnosing, treating, or preventing health conditions. The goal is to determine whether a substance is both safe and effective. A clinical trial is only done when there is strong reason to believe that a new test or treatment may improve the care of patients.

A variety of treatment methods such as medications, medication combinations, new uses for existing medications, and medical devices are evaluated through clinical trials. In the United States, all new treatments must go through these trials before being approved for public sale by the Food and Drug Administration (FDA).

At the discovery and development stages, thousands of compounds may be potential candidates for development into a “drug”. After early testing, however, only a small number of compounds look promising and call for further study. The entire process of developing a drug from its pre-clinical research stage to its final marketing phase can take approximately 12 to 18 years and often costs well over $1 billion [3, 4].

Clinical trials show us what works and what does not in the realm of healthcare and are designed to answer some important questions such as:

• Does the new treatment work in people? If it does, how effective is it?
• Is it better than currently used treatments?
• If it is not better, is it just as good and cause fewer side effects?
• Does it work in some people who do not benefit from current treatments?
• Is the new treatment relatively safe? There is virtually no treatment or procedure that is without risk, but do the benefits of the new treatment outweigh the risks?

Answering these questions, while giving as few people as possible an unknown treatment, often requires several clinical trials in different phases. Each phase is designed to answer certain questions while keeping trial participants as safe as possible.

Preclinical phase

Before clinical trials can begin in humans, tests and treatments are assessed in pre-clinical research, which can involve extensive laboratory research over several years of testing on animals and human cells. This research may aim to learn the chemical compound of a drug [1]. If the initial laboratory research is successful, researchers send the data to health authorities for approval in order to begin research and testing on humans.

Once pre-clinical research results are approved, human testing of experimental drugs can begin and is typically conducted in four phases that are denoted by Roman numerals (Phase I, II, III and IV). Each phase is considered a separate trial and, after completion of a phase over many years, researchers are required to submit their data to, and then wait for approval from their local health agency (the FDA in the US) before continuing onto the next phase. If the drug successfully passes through Phases I, II, and III then it will usually be approved by the national regulatory authority for use in the general population. Phase IV trials are “post-marketing” or “surveillance” studies that are conducted to monitor how safe the product is over several years [2].

Phase I

This is the first clinical phase that involves humans. Phase I trials most often include healthy volunteers, however there are some circumstances when clinical patients are used, such as patients who have terminal cancer or HIV. These treatments possess a much higher risk for healthy individuals and could cause to become ill and contract serious adverse side effects.

In a Phase I clinical trial, doctors collect information on:

• The dose or treatment
• When it should be taken, and how often
• Any side effects or complications
• How the treatment affects patients and their preexisting conditions

One of the primary goals of Phase I studies is to find the highest dose of a new treatment that can be given safely without causing severe side effects. Although the treatment has been tested in laboratory and most likely been used in animal studies, the side effects in people cannot be known for sure. During Phase I of a clinical trial, researchers spend several months to evaluate safety, side effects, optimal dosage amounts, and formulation method for the drug on about 20 to 80 people who have no underlying health conditions.

In addition to evaluating safety and ideal dosage, specialists also look at the best way to administer the drug such as orally, intravenously, or topically. These trials are often conducted in a clinical trial clinic where the subject can be observed by full-time staff. Safety always remains the foremost concern in Phase I. The research team keeps a close eye on the people and watches for any severe side effects.

Researchers start by giving very low doses of the drug to a few patients while higher doses are given to other patients until side effects become too severe or desired effects are seen. The drug may help patients, but Phase I trials are to test a drug’s safety. If a drug is found to be safe enough, it can be tested in a Phase II clinical trial. According to the FDA, approximately 70 percent of medications move on to Phase II.

Phase 2

Phase II of a clinical trial usually involves anywhere from 50 to several hundred who are living with the condition that the new medication is meant to treat. They are usually given the same dose that was found to be safe in the previous phase. Investigators monitor participants for several months, or years, to see how effective the medication is and to gather more information about any side effects it might cause.

Most phase II studies are randomized trials where one group of patients receives the experimental drug, while a second “control” group receives a standard treatment or placebo. These studies are mostly “blinded” which means that neither the patients nor the researchers know who has received the experimental drug in order to avoid from bias. Doctors use a computer program to randomly sort volunteers into these two separate groups. Each volunteer has an equal chance of ending up in any of the groups and are randomly put in any group.

This allows investigators to provide the pharmaceutical company and the health authority with comparative information about the relative safety and effectiveness of the new drug. When the development process for a new drug fails, this usually occurs during Phase II trials when the drug is discovered to not to work as planned or to have toxic effects. The FDA estimates that roughly one-third of experimental drugs successfully complete both Phase I and Phase II studies.

Phase II clinical programs historically have experienced the lowest success rate of the four development phases. In 2010, the percentage of Phase II trials that proceeded to Phase III was 18% [5] and only 31% of developmental candidates advanced from Phase II to Phase III in a large study of clinical trials conducted during the period of 2006 – 2015 [6].

Phase III

Phase III of a clinical trial usually involves up to 3,000 participants who have the condition that the new medication is meant to treat. These participants must include men, women, and people of different ages and ethnic groups in many places across the country (or even around the world) at the same time. This helps doctors learn how treatment works in different people with different genetic backgrounds, races, and ethnicity. These studies tend to last longer – up to several years – than Phase I and II studies.

One of the additional purposes of Phase III is to evaluate how the new medication works in comparison to existing medications for the same condition. To move forward with the trial, investigators need to demonstrate that the medication is at least as safe and effective as existing treatment options. Due to the larger number of participants and longer duration of Phase III, rare and long-term side effects are more likely to show up during this phase.

There can be more than two treatment groups in Phase III trials. The control group may receive the current standard-of-care treatment for their illness while other groups receive the new treatment on trial. Phase III trials are usually double blinded to eliminate bias when interpreting results.

Placebos may be used in some Phase III studies, but they are never used alone if there is a treatment available that works. Sometimes, a patient who is randomly assigned to the placebo for part of the study will at some point be offered the standard treatment as well. As with other trials, patients in Phase III clinical trials are watched closely for side effects, and treatment is stopped if they become too hard to manage.

Every patient in a Phase III study is watched closely, and the study will be stopped early if the side effects of the new drug are too severe or if one group has significantly better results. Phase III clinical trials are often needed before the FDA will approve the use of a new drug for the general public. If researchers demonstrate that the medication is at least as safe and effective as others already on the market, then the FDA will usually approve the medication.

In the United States, when Phase III clinical trials (or sometimes Phase II trials) show a new drug is more effective or safer than the current treatment, a new drug application (NDA) is submitted to the FDA for approval. The FDA reviews the results from the clinical trials and other relevant information.

Based upon the review, the FDA then decides whether to approve the treatment for use in patients with the illness the drug was tested on. If approved, the new treatment often becomes a standard of care and newer drugs may be tested against it before they can be approved. If the FDA feels that more evidence is needed to show that the new treatment’s benefits outweigh its risks, it may ask for more information or even require that more studies be done. Once Phase III is complete, a pharmaceutical company can request FDA approval to begin marketing the drug. Roughly 25 to 30 percent of medications move on to Phase IV.

Phase IV

Phase IV trials test new drugs that are approved by health authorities and often are called Post Marketing Surveillance Trials. The drugs are available for doctors to prescribe to patients, but Phase IV studies might still be needed to answer important questions. In previous clinical phases the drug may not have been tested for interactions with other drugs, or on certain population groups, such as pregnant women, who are unlikely to subject themselves to trials. This phase involves thousands of participants and can last for many years. Investigators use this phase to get more information about the medication’s long-term safety, effectiveness, and any other benefits.

This is often the safest type of clinical trial because the treatment has already been studied a lot and has likely been given to many people. Phase IV studies look at safety over time. These studies may also look at other aspects of the treatment, such as quality of life or cost effectiveness.

Phase IV studies can result in a drug or device being taken off the market or restricted depending on the findings in the study. Unless an adverse effect of the approved drug is shown or the drug is accepted as safe, it will stay on the market and also in Phase IV forever.

This clinical trial algorithm has come out after many scientific studies. Every point of the clinical trials, and possible problems, have been clarified by policies which may differ from country to country. At the end, clinical trials are a very safe and cautious method of finding out the safest and most effective treatment, or diagnostic method, for people. During clinical trials, scientists are very careful about ethical issues and try not to harm any living organisms, be them animals or humans. There is an ongoing public debate over pharmaceutical companies. While some think they play a major role in the emergence of many methods and scientific developments to benefit human health, others doubt their motivations and questions their contribution to the public good. This debate will surely continue for a long time, but under the current circumstances, pharmaceutical companies are found in the center of all these clinical trials described in this article. Regardless of the truth behind these doubts, it is important to be always aware of the priceless value of life, that it has been given to us and all living things as an inalienable right and a precious gift, and that it is a major responsibility take care of it well and seek healing when needed.

• https://www.nccn.org/patients/resources/clinical_trials/phases.aspx
• “The drug development process”. US Food and Drug Administration. 4 January 2018. Retrieved 17 August 2020
• Holland J (2013). “Fixing a broken drug development process”. Journal of Commercial Biotechnology. 19. doi:10.5912/jcb588.
• Adams CP, Brantner VV (2006). “Estimating the cost of new drug development: is it really 802 million dollars?”. Health Affairs. 25 (2): 420–8. doi:10.1377/hlthaff.25.2.420. PMID 16522582.
• “New drugs failing Phase II and III clinical trials”. MedCity News. 2011-06-02.
• “Clinical Development Success Rates 2006-2015” (PDF). bio.org. Retrieved 2018-02-11.

It has been over half a year since Covid-19 swept across the world and forced many countries into quarantine. Hopes of a quick resolution of the disease in many countries have since been, unfortunately, proven to be wrong, and it is evident that the virus is here to stay for a while [1]. The virus is so difficult to deal with considering it can be transferred from person to person even if the carrier does not outwardly display symptoms. Even animals, ranging from mice to tigers, can contract and transmit it to humans [2, 3], and we cannot quarantine or force them to wear facemasks. The virus will eventually hit each person; it is just a matter of time. The virus may additionally arrive in multiple waves, as it is possible to be reinfected [4]. COVID-19 will most likely have a lifespan of a few years, much like other major virus outbreaks of the past such as the swine flu in Hong Kong or Spanish flu. It will probably come and go like a common flu in never ending waves. So, each of us need to be ready until a successful vaccine is developed, and the wisest action for each person to be ready would be to boost our immune systems and practice effective social distancing and sanitation measures, while we deal with this virus for however long it may last.

Vaccines are critical for stunting the development and spread of viruses; however, they can be costly, time-intensive to develop, and not always perfect. It is worth exploring alternative methods to help protect our bodies from these pathological invaders while vaccines are being researched. As it so happens, the best method of prevention to date for HIV infections is not a vaccine, but is instead a tradition that is as old as thousands of years: male circumcision [5]. To give a comparison, the current widely popular and heavily promoted influenza vaccine is considered “50% effective against influenza B/Victoria viruses and 37% effective against influenza A(H1N1)” [6]. On the other hand, according to an article published in the prestigious medical journal, The Lancet, circumcision is up to 88% effective in preventing heterosexual transmission of HIV [7]. Male circumcision does not have any medicinal side effects, and the only risks that are involved are those related to any minor surgery – bleeding and infection.

In the 1980s, when I first heard of HIV, I remember reading articles which claimed, quite arrogantly, that vaccines and cures for the condition would be found within two or three years [8]. Forty years later, and after spending many billions of dollars on research, we are still nowhere near an HIV vaccine. At best, we found treatments which helped keep the HIV virus at bay [9]. To date, only two people have been fully cured with a method far too expensive to be applied to the general public [10]. In the meantime, at least 30 million people have died with more than half a million in the year 2019 alone [11]. While vaccines are critical for helping to eradicate viruses, putting all of our eggs into that basket alone can be a risky public health strategy due to how difficult and time consuming they are to discover, verify, and distribute. It is impossible to know for sure how long it will take to develop a vaccine for the coronavirus. In the meantime, communities should heavily consider following the instructions of their local health officials which often include social distancing, limited size gatherings, and frequent hand washing as these methods are already proven to help reduce the spread of the virus.

Development, and even the rushed development of a vaccine, is always a very tedious and dangerous process. The science behind them is exceptionally complex, and imperfect results can have disastrous consequences upon thousands of people. This is further complicated by the fact that phase 2 and phase 3 trials can have quite diverging results [12]. In the USA, AstraZeneca’s COVID-19 vaccine trials were stopped after trial participants fell ill [13]. Third phase trials, which encompass thousands of people [14], still can give little indication of the long-term side effects to any vaccine. Besides, even though there is human life at risk, the vaccine has already become an instrument for many political and economic disputes and conspiracy theories. Some governments claim they have already developed a vaccine, while others find them unreliable, or try to lure a foreign company to work for themselves [15]. In August of this year Russia rushed registration of an unproven Coronavirus vaccine and named it, in Cold-War-like fashion, the “Sputnik V” [16]. The announcement was made by none other than Vladimir Putin himself. It was offered to the USA, but was rejected due to safety concerns stemming from a belief that the drug was not adequately researched and developed [17]. In the meantime, Russia announced the development of a second vaccine [18]. Surely enough, it was dismissed and downplayed by the West as unproven and unreliable. On the other hand, a vaccine developed by a Chinese company Sinovac proved to be the most successful in its phase 3 trials in Brazil [19]. Sao Paulo Governor João Doria purchased 47 million shots of the vaccine. However, the transaction was stopped, arguably for political reasons, by the Brazilian President Jair Bolsonaro [20]. Bolsonaro’s comments when rejecting the purchase of the Sinovac vaccine on the basis that “the Brazilian people will not be anyone’s guinea pig” are not totally without merit. Recalls of “proven and tested” vaccines have happened in the past [21].

It is important for all people to continue exploring methods to develop their immune systems and prevent the spread of the virus while we wait for a vaccine. In an article I had previously published, I discussed the benefits of fasting, vitamin C, and Wim Hof breathing methods to help protect the body from disease [22]. All of these methods are well known and quite benign with respect to side effects, however they are unable to cure Covid-19 or prevent its spread. Additionally, the Center for Disease Control (CDC) has heavily stressed practices included social distancing and the wearing of non-ventilated face masks. Our hope is that going above and beyond to protect ourselves and our neighbors will give scientists the time that they need.

One way of giving that time to scientists is fasting. Fasting, like circumcision, is a tradition that is thousands of years old. In recent studies, a three-day water fast has been shown to reset the immune system of elderly people to the level of a twenty-year old’s [23]. At this current level of emergency in the world it would be very easy to find thousands of willing volunteers to trial monthly three-day water fasts and/or to take extra doses of vitamin C, not as a cure, but as a shield against COVID-19. This kind of study would not pose much risk and would definitely be very cost-effective. We could dive straight into the third phase of trials, for any side effects of fasting are already well known. And finally, if proven effective, its uptake by the population at large would be basically cost free and readily available across the whole world.

Our world has been enduring a difficult and challenging period for the better half of a year now. Time has given us the ability to learn more about the virus, how it disrupts our bodies, and how it spreads. This knowledge has, in turn, allowed us to research it and develop effective social guidelines for limiting its spread. Still, there is much work to be done. Hysteria and haste are not conducive to producing a vaccine that is thorough, effective, and efficient. It should be the responsibility of every able-bodied citizen to do what they can to learn more about how they can protect themselves from the virus and thus prevent it from spreading even more while we wait for a vaccine.

1. https://www.wuky.org/post/beshear-next-few-weeks-will-be-critical#stream/0
2. https://www.washingtonpost.com/science/2020/09/03/coronavirus-deer-mice-spread/
3. https://www.cdc.gov/coronavirus/2019-ncov/daily-life-coping/animals.html
4. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7326402/
5. https://www.thelancet.com/journals/lancet/article/PIIS0140-6736(99)03421-2/fulltext?_eventId=login
6. https://www.aafp.org/news/health-of-the-public/20200226interimfluve.html
7. Halperin, D. T., & Bailey, R. C. (1999). Male circumcision and HIV infection: 10 years and counting. The Lancet, 354(9192), 1813-5. doi:http://dx.doi.org/10.1016/S0140-6736(99)03421-2
8. https://www.immunology.org/publications/bsi-reports/60-years-immunology-past-present-and-future/the-hunt-for-hiv-vaccine
9. https://www.cdc.gov/hiv/basics/livingwithhiv/treatment.html
10. https://www.medicalnewstoday.com/articles/2nd-person-cured-of-hiv-thanks-to-stem-cell-transplant
11. https://www.unaids.org/en/resources/fact-sheet
12. https://www.fda.gov/media/102332/download
13. https://www.usatoday.com/story/news/health/2020/09/09/covid-vaccine-astrazeneca-trial-hold-what-does-mean/5757590002/
14. cancer.org/treatment/treatments-and-side-effects/clinical-trials/what-you-need-to-know/phases-of-clinical-trials.html
15. 15 https://www.nytimes.com/2020/03/15/world/europe/cornonavirus-vaccine-us-germany.html
16. https://www.theverge.com/2020/8/11/21363135/russia-coronavirus-vaccine-unproven-registration
17. https://www.techtimes.com/articles/251792/20200814/covid-19-us-says-no-to-russias-vaccine-sputnik-v-saying-theyll-never-use-it-on-monkeys-let-alone-people-vietnam-and-philippines-say-otherwise.htm
18. https://abcnews.go.com/Health/wireStory/russia-approves-2nd-virus-vaccine-early-trials-73614460
19. https://fortune.com/2020/10/20/covid-vaccine-china-brazil-testing-ground-safest-most-promising-sinovac/
20. https://apnews.com/article/virus-outbreak-brazil-state-governments-health-sao-paulo-b7b5b620ba54f402dbf803e26fe6b842
21. https://www.cdc.gov/vaccinesafety/concerns/recalls.html
22. https://medium.com/@arasweb/surviving-the-pandemic-370b47120d8d
23. https://news.usc.edu/63669/fasting-triggers-stem-cell-regeneration-of-damaged-old-immune-system/

Almost all of us are familiar with the fact that our bodily organs are composed of tissues, which are made of cells. The perfect machinery of the cells is controlled by our genes; i.e. DNA and RNA. Therefore, a minor defect or mutation in the genetic code may affect either partial or entire systems within the body. Some of these genetic diseases are inherited from our parents or relatives. Others may be introduced into our body through environmental mutagens, such as ionizing radiation, ultraviolet rays, or different chemicals within our food and drink; these can result in cancer or cardiovascular diseases. We can protect ourselves from the latter by using appropriate outfits, taking care with our diet, etc. However, inherited genetic disorders are usually unavoidable and sometimes have fatal consequences. Modern medicine is striving to find a way to treat these diseases. Although there are some medical procedures that may lessen the pain of patients or extend their life expectancy, there is no available comprehensive curative therapy for genetic disorders.

Gene therapy has become one of the rising stars in the field of molecular medicine during the last decade, with more than 1500 proposed or ongoing clinical trials worldwide. Gene therapy promises to provide curative therapies for a large number of inherited or acquired diseases, such as monogenic disorders, cancer, or cardiovascular disease. Gene therapy is universally defined as the replacement of an abnormal/dysfunctional gene in the cells of an individual with its correct and functional version. Mechanics use a number of tools to fix our cars for us when they give us trouble; in the same way, gene therapy can be used by doctors to alleviate or completely eradicate some diseases from our bodies.

Gene therapy is classified into two categories based on the target cells that are to be treated. The transduction of the differentiated cells of an individual, i.e. the somatic cells, is known as somatic gene therapy; the transduction of reproductive cells, i.e. gametes (sperm or ova), is known as germ-line gene therapy. Currently, there are many regulations in place that limit the likelihood of the modification of the germline in any gene therapy approach. This is because fear exists that the ability to alter the germline will result in the widespread application of gene therapy to achieve eugenic genetic enhancements, such as improvement of intelligence or physical characteristics. On the other hand, transgenic animals, which are used to detect the function of the genes within an organism, can be generated by modifying the germ-line. Furthermore, gene therapy is also classified into two groups: adult and fetal (in utero) gene therapy, according to the individual to be treated. There are several advantages and disadvantages to these methods, such as immune response, the pooling of mitotic cells, the amount of vector that is required, etc.; however, these are matters for a different article.

Gene therapy is achieved by using special exogenous genetic material transfer agents which are called vectors; these can be compared to the special tools used by auto mechanics. Over the years, a number of gene transfer vehicles, i.e. vectors, have been developed and these can be divided into two principal categories: non-viral (synthetic) and viral (virus-based) gene delivery systems.

Non-viral gene transfer can be achieved by using both physical and chemical methods. The physical methods include: i) Electroporation, in which areas of the cell membrane break down as result of an applied electric pulse, thus allowing DNA to enter the cell, ii) Ballistic gene transfer (the Gene Gun), which bombards particles coated with DNA into the cells, and iii) Microinjection, in which DNA is transferred through microcapillaries into the cells [1]. In terms of chemical gene transfer, lipofection is the most promising method; in this method negatively-charged DNA molecules bind to cationic lipid particles through electrostatic interaction and the DNA–lipid complex enters the cell through endocytosis/pinocytosis. Although these non-viral delivery systems exhibit low toxicity and can be easily produced in high concentrations on a commercial scale, in general, gene transfer using these agents is inefficient and often transient. Therefore, as a result of the viral vectors’ ability to efficiently deliver and integrate genes into the host genome, they are being engineered extensively to achieve a sustained and high-level expression of the gene of interest (transgene).

Viral vectors

Have you ever thought that one of the major pathological agents that cause catastrophic and even fatal diseases could be used to treat the same or a similar disease?

Viruses are equipped with specialized molecular mechanisms that allow them to efficiently transport the genomes into the cells they infect and use the cell’s machinery for their own reproduction. Molecular biologists first harnessed this machinery of transduction in the 1970s. Paul Berg used a modified SV40 virus containing DNA from the bacteriophage lambda to infect monkey kidney cells that were being maintained in culture. Viral delivery systems are based on replicating viruses that have the ability to deliver genetic information into the host cell, a process known as transduction [2]. Due to the fact that there are several advantages to viral vectors, these are the vehicles being employed in approximately 75% of all ongoing clinical trials worldwide. Numerous viruses are being used as the basis for the vectors, including, but not limited to, adenovirus (24%, n=377), retrovirus (20.9%, n=329), adeno-associated virus (4.3%, n=67), herpes simplex virus (3.2%, n=51), vaccinia virus (7.9%, n=124), poxvirus (5.8%, n=91), and baculovirus (more detailed information is available at www.wiley.co.uk/genmed/clinical). The first step to construct a viral vector for transferring the gene of interest involves the identification of the viral sequences that are necessary for replication and pathogenesis. Then some of the genes are removed to make room for the transgene and to render the viral vector replication-incompetent. Consequently, the vector is unable to replicate within the host, and therefore is safe for delivering genes to human cells or tissues (Figure 1).

There are advantages and disadvantages to all of the currently available vectors; the suitability of the vector, therefore, actually depends on the disease or condition that is being treated. For instance, if the goal of the gene therapy is to increase bone marrow engraftment with the transient expression of a growth factor, the use of chemical transfection or naked DNA transfer methods would suffice. However, if the objective is to provide long-term treatment for an inherited disease, then the use of an integrating viral vector is more desirable. Thus, a vector that might be ideal for treating one defect may not be ideal for another. Driven by the desire to develop the “perfect” vector, scientists are continually striving for novel forms of gene delivery that might become the “magic bullet.” Somia and Verma [3] have proposed that the ideal gene therapy vector should include all of the following properties: 1) easy production at a high titer on a commercial scale with a reasonable shelf-life for transport and distribution 2) sustained or regulated expression of the transgene product that is adjustable to the nature of the disease, 3) absence of immune response against the vector and the transgene product, 4) ability to target specific tissues and/or cell types while avoiding professional antigen-presenting cells, 5) absence of size limitations for the genetic material to be delivered by the vector, 6) site-specific integration of the transgene into the chromosome of the target cell to avoid insertional mutagenesis, or faithful division and segregation if it is to reside in the nucleus as an episome independent of local chromatin environments, and 7) an ability to infect dividing and post-mitotic cells. Unfortunately, none of the currently available gene delivery vectors carry all of these features; however, many vectors have enough of the attributes to make them promising for clinical use.

Candidate diseases

During the last 4 decades, gene therapy for many diseases has progressed from preclinical to clinical studies; these range from monogenic recessive disorders such as hemophilia and cystic fibrosis to more complex diseases such as cancer, cardiovascular disorders, human immunodeficiency virus (HIV), neurological and ocular pathologies. The prevalence of diseases that fall under the scope of gene therapy is enormous and most of them have catastrophic or fatal outcomes. Therefore, gene therapy approach for almost any of the diseases mentioned above has an obvious appeal and rationale. To date, more than 1,540 gene therapy clinical trials have been initiated, and these are continuing or have been completed in 28 countries, using more than 100 genes, including antigens, cytokines, tumor suppressors, growth factors, and deficiency genes [4].

Candidate monogenic disorders that are considered to be good candidates for treatment by gene therapy include the hemoglobinopathies, X-linked genetic disorders, amino acid metabolism disorders, and lysosomal and other storage diseases. Currently, there are more than 4000 monogenic diseases registered in the OMIM database. The ultimate aim in treating monogenic diseases with gene therapy is the correction of the disorder by the stable transfer of the functioning gene into dividing cells (stem/progenitor cells), which will ensure the permanence of the correction [5]. The first recognized successful clinical gene therapy trial involved the treatment of 11 children who suffered from SCID-X1 (Severe Combined Immunodeficiency), an X-linked inherited monogenic disorder caused due to a mutation in the common cytokine receptor gamma chain (γc). In these patients, immunity was not fully developed due to the blocking of T-cell and natural killer cell development as a result of mutation. Unfortunately, the trial in SCID-X1 also exemplified one of the potentially serious side effects of gene therapy. Three of the children developed uncontrolled clonal T-cell proliferation, that is, leukemia, almost 3 years after treatment. This case was associated with the integration of the retroviral vector close to the promoter of the LMO-2 proto-oncogene. As a result, LMO-2 protein expression was up-regulated in an abnormal way and resulted in leukemia [7]. Another candidate monogenic disorder for gene therapy is cystic fibrosis (CF), in which abnormally thick mucus is produced in the lungs of the patients, causing difficulty in breathing and increasing the frequency of serious lung infections. CF is known as the most common inherited genetic disease in Europe and USA, especially within the Ashkenazi Jewish population. The average life expectancy of patients with CF is less than 40 years; hence the treatment of this disease has become one of the prime targets of gene therapy research.

In addition to its use in the treatment of monogenic diseases, gene therapy is also becoming a therapeutic alternative for the treatment of various forms of cancer. Indeed, almost 65% of ongoing clinical trials are related to cancer (more detailed information is available at www.wiley.co.uk/genmed/clinical), an area in which much more promise can be seen; this is also a reflection of the urgent need for new therapies to tackle the escalating incidence of this disease. Several different principles are used to treat cancer, including gene therapy that is targeted at tumor suppressor genes, such as p53, or central signaling molecules, as well as “suicide gene” therapy, in which the transgene is capable of converting pro-drugs (selectively less active drugs) into drugs that are toxic for tumor cells. Furthermore, various gene therapy protocols have been developed to strengthen the host’s anti-tumor immune responses by immunotherapy. Most of these studies have been early clinical trials designed primarily as studies of the safety, applicability, and toxicity of gene therapy. Several of these phase I and II studies have, however, shown partial remission of tumors and, in rare cases, complete remission. However, complete cure of the tumor has not yet been achieved. In some trials, including TP53 gene therapy trials, regression in tumor size has been observed in up to 50% of patients. China has become the first country to license gene therapy as a regular treatment for neck and head cancer; here Gendicine, a replication-defective Ad5 vector expressing p53 from a Rous sarcoma virus (RSV) promoter, is used for therapy [6].

In addition to its applications for cancer and monogenic diseases, gene therapy has become one of the favorite methods in cardiovascular research field. This is in step with the rise in clinical trials for cardiovascular gene therapy from 8.3% to 9.1% during the last few years, becoming the second most popular application for gene therapy. In accordance with the variety and occurrence of cardiovascular diseases, different gene therapy strategies have been developed to tackle each disease on its own terms. The expectation is that gene therapy will provide a new avenue for therapeutic applications in the growth of blood vessels, as well as the protection, regeneration, and repair of heart tissue, the prevention of the reoccurrence of constricted or narrowed arteries following cardiovascular intervention, the prevention of the rejection of a bypass, and risk-factor management [4]. Long-term therapeutic gene expression is required in some diseases, such as hypertension research, where reversal and prevention are the key targets. On the other hand, for some other types of cardiovascular diseases, such as ischemia, atherosclerosis, and restenosis, shorter-term gene control will be sufficient to prevent further progress of the symptoms. Therefore, different gene-therapy vectors have to be considered for the treatment of each specific cardiovascular disorder.

Consequently, gene therapy offers new avenues of treatment for diseases including monogenic disorders, cancer, cardiovascular diseases, infectious pathologies and many more. As we follow the tradition, “God did not send down any illness for which He did not also send a cure (Bukhari)”, gene therapy using either viral, non-viral, or any other novel methods may pave the way for the cure of many diseases that are highly prevalent in the world and which for decades have been perceived as untreatable.

Dr. Ferhat Ozturk is a postdoctoral research associate at University of Nebraska Medical Center.

References

1. Wells DJ. “Gene therapy progress and prospects: electroporation and other physical methods.” Gene Ther. 2004 Sep;11(18):1363-9.
2. Kootstra, N.A. and I.M. Verma, “Gene therapy with viral vectors.” Annu Rev Pharmacol Toxicol, 2003. 43: p. 413-39.
3. Somia, N. and I.M. Verma, “Gene therapy: trials and tribulations.” Nat Rev Genet, 2000. 1(2): p. 91-9.
4. Edelstein, M.L., M.R. Abedi, and J. Wixon, “Gene therapy clinical trials worldwide to 2007–an update. J Gene Med, 2007. 9(10): p. 833-42.
5. http://www.biomedisch.nl/en/gene_therapy_targeted_diseases.php
6. Peng, Z., “Current status of gendicine in China: recombinant human Ad-p53 agent for treatment of cancers.” Hum Gene Ther, 2005. 16(9): p. 1016-27.
7. Cavazzana-Calvo M, Fischer A, Gene therapy for severe combined immunodeficiency: are we there yet? J Clin Invest. 2007 June. 117(6):1456-65

American Indians applied its leaves as a poultice to heal wounds, and brewed a cough mixture from its roots. Now its seeds are claimed to have medicinal uses ranging from relieving pre-menstrual syndrome to management of multiple sclerosis, alcoholism and atopic eczema.

The seeds contain approximately 15% protein, 24% oil and 43% cellulose and lignin. The fatty acids in the oil are thought to be important to health because the oil contains 65-85% linoleic acid (LA) and 7-15% gamma linoleic acid (GLA): LA is an essential fatty acid for the body which it cannot make but which it converts to GLA. GLA is one of the components of cells and a precursor of prostaglandins which regulate many body functions. However, the LA GLA conversion step may be blocked by a range of factors including excessive levels of blood cholesterol, a high proportion of certain fatty acids in the diet, ageing, alcohol intake and diabetes.

Supplementing the diet with evening primrose oil (EPO) by-passes the conversion step, thus providing for the presence of GLA in the body. A recent World Health Organisation report suggested that 3% of the total calorific intake of adults should be in the form of essential fatty acids, this figure rising to 5-6% for children and pregnant and lactating women. GLA can be provided by several other sources as well, e.g. borage oil and blackcurrant oil, both of which contain a higher concentration of GLA than EPO but not as much LA.

The quality and composition of EPO used in commercial manufacturing is currently the subject of much research and monitoring work. In the UK research is concentrated on obtaining GLA from other sources e.g. by fermentation from the fungus mucor javanicus.

A concentrated oil from evening primrose, borage and blackcurrant seeds, is now undergoing clinical trials and may be used in second generation oil products of the future. EPO is already used in a variety of beauty and hygiene products, including cosmetic and skin care products, shampoos and soaps.

Trials have been curried out to investigate claims of the effectiveness of EPO in treating many diseases and conditions, including multiple sclerosis, cardiovascular disease, asthma, atopic eczema, cancer, obesity and premenstrual syndrome. So far the results have been variable but some genuine clinical effects have been seen.

Millions of dollars have been and are being spent on developing new methods of extracting useful natural products for the benefit of mankind. We are now seeing a widespread desire to return to natural resources to cure various ailments. Let us hope that, before mankind destroy their environment, they will come to realize the importance of nature’s medicine-cabinet, and give thanks where it is due. Without that giving of thanks, mankind will not practise the humility and compassion necessary if our common resources are to be preserved both for ourselves and for future generations.