New drug for schizophrenia could meet desperate need for better treatments
Schizophrenia is a debilitating mental health condition that affects around 24 million people worldwide. Patients experience hallucinations and delusions when they develop schizophrenia, with experts referring to these new thoughts and behaviors as positive symptoms. They also suffer from negative symptoms in which they lose important functions, suffering from dulled emotions, lack of purpose and social withdrawal.
Currently available drugs can control only a portion of these symptoms but, on August 8th, Karuna Therapeutics announced its completion of a phase 3 clinical trial that found a new drug called KarXT could treat both positive and negative symptoms of schizophrenia. It could mean substantial progress against a problem that has stymied scientists for decades.
A long-standing problem
Since the 1950s, antipsychotics have been used to treat schizophrenia. People who suffer from it are thought to have too much of a brain chemical called dopamine, and antipsychotics work by blocking dopamine receptors in the brain. They can be effective in treating positive symptoms but have little impact on the negative ones, which can be devastating for a patient’s quality of life, making it difficult to maintain employment and have successful relationships. About 30 percent of schizophrenia patients don't actually respond to antipsychotics at all. Current drugs can also have adverse side effects including elevated cholesterol, high blood pressure, diabetes and movements that patients cannot control.
The recent clinical trial heralds a new treatment approach. “We believe it marks an important advancement for patients given its new and completely different mechanism of action from current therapies,” says Andrew Miller, COO of Karuna.
Scientists have been looking to develop alternatives. However, “the field of drug treatment of schizophrenia is currently in the doldrums,” says Peter McKenna, a senior researcher at FIDMAG Research Foundation in Spain which specialises in mental health.
In the 2000s there was a major push to target a brain receptor for a chemical called glutamate. Evidence suggested that this receptor is abnormal in the brains of schizophrenia patients, but attempts to try glutamate failed in clinical trials.
After that, many pharmaceutical companies dropped out of the race for a more useful treatment. But some companies continued to search, such as Karuna Therapeutics, led by founder and Chief Operating Officer Andrew Miller and CEO Steve Paul. The recent clinical trial suggests their persistence has led to an important breakthrough with their drug, KarXT. “We believe it marks an important advancement for patients given its new and completely different mechanism of action from current therapies,” Miller says.
How it works
Neurotransmitters are chemical messengers that pass signals between neurons. To work effectively, neurotransmitters need a receptor to bind to. A neurotransmitter called acetylcholine seems to be especially important in schizophrenia. It interacts with sites called muscarinic receptors, which are involved in the network of nerves that calm your body after a stressful event. Post mortem studies in people with schizophrenia have shown that two muscarinic receptors in the brain, the M1 and M4 receptors, are activated at unusually low levels because they don’t receive enough signals from acetylcholine.
The M4 receptor appears to play a role in psychosis. The M1 receptor is also associated with psychosis but is primarily thought to be involved in cognition. KarXT, taken orally, works by activating both of these receptors to signal properly. It is this twofold action that seems to explain its effectiveness. “[The drug’s] design enables the preferential stimulation of these muscarinic receptors in the brain,” Miller says.
How it developed
It all started in the early 1990s when Paul was at pharmaceutical company Eli Lilly. He discovered that Xanomeline, the drug they were testing on Alzheimer's patients, had antipsychotic effects. It worked by stimulating M1 and M4 receptors, so he and his colleagues decided to test Xanomeline on schizophrenia patients, supported by research on the connection between muscarinic receptors and psychosis. They found that Xanomeline reduced both positive and negative symptoms.
Unfortunately, it also caused significant side effects. The problem was that stimulating the M1 and M4 receptors in the brain also stimulated muscarinic receptors in the body that led to severe vomiting, diarrhea and even the temporary loss of consciousness.
In the end, Eli Lilly discontinued the clinical trials for the drug, but Miller set up Karuna Therapeutics to develop a solution. “I was determined to find a way to harness the therapeutic benefit demonstrated in studies of Xanomeline, while eliminating side effects that limited its development,” Miller says.
He analysed over 7,000 possible ways of mixing Xanomeline with other agents before settling on KarXT. It combines Xanomeline with a drug called Trospium Chloride, which blocks muscarinic receptors in the body – taking care of the side effects such as vomiting – but leaves them unblocked in the brain. Paul was so excited by Miller’s progress that he joined Karuna after leaving Eli Lilly and founding two previous startups.
“It's a very important approach,” says Rick Adams, Future Leaders Fellow in the Institute of Cognitive Neuroscience and Centre for Medical Image Computing at University College London. “We are in desperate need of alternative drug targets and this target is one of the best. There are other alternative targets, but not many are as close to being successful as the muscarinic receptor drug.”
Clinical Trial
Following a successful phase 2 clinical trial in 2019, the most recent trial involved 126 patients who were given KarXT, and 126 who were given a placebo. Compared to the placebo, patients taking KarXT had a significant 9.6 point reduction in the positive and negative syndrome scale (PANSS), the standard for rating schizophrenic symptoms.
KarXT also led to statistically significant declines in positive and negative symptoms compared to the placebo. “The results suggest that KarXT could be a potentially game-changing option in the management of both positive and negative symptoms of schizophrenia,” Miller says.
Robert McCutcheon, a psychiatrist and neuroscientist at Oxford University, is optimistic about the side effects but highlights the need for more safety trials.
McKenna, the researcher at FIDMAG Foundation, agrees about the drug’s potential. “The new [phase 3] study is positive,” he says. “It is reassuring that one is not dealing with a drug that works in one trial and then inexplicably fails in the next one.”
Robert McCutcheon, a psychiatrist and neuroscientist at Oxford University, said the drug is an unprecedented step forward. “KarXT is one of the first drugs with a novel mechanism of action to show promise in clinical trials.”
Even though the drug blocks muscarine receptors in the body, some patients still suffered from adverse side effects like vomiting, dizziness and diarrhea. But in general, these effects were mild to moderate, especially compared to dopamine-blocking antipsychotics or Xanomeline on its own.
McCutcheon is optimistic about the side effects but highlights the need for more safety trials. “The trial results suggest that gastrointestinal side effects appear to be manageable,” he says. “We know, however, from previous antipsychotic drugs that the full picture regarding the extent of side effects can sometimes take longer to become apparent to clinicians and patients. Careful ongoing assessment during a longer period of treatment will therefore be important.”
The Future
The team is currently conducting three other trials to evaluate the efficacy and long-term safety of KarXT. Their goal is to receive FDA approval next year.
Karuna is also conducting trials to evaluate the effectiveness of KarXT in treating psychosis in patients suffering from Alzheimer’s.
The big hope is that they will soon be able to provide a radically different drug to help many patients with schizophrenia. “We are another step closer to potentially providing the first new class of medicine in more than 50 years to the millions of people worldwide living with schizophrenia,” says Miller.
Today’s Focus on STEM Education Is Missing A Crucial Point
I once saw a fascinating TED talk on 3D printing. As I watched the presenter discuss the custom fabrication, not of plastic gears or figurines, but of living, implantable kidneys, I thought I was finally living in the world of Star Trek, and I experienced a flush of that eager, expectant enthusiasm I felt as a child looking toward the future. I looked at my current career and felt a rejuvenation of my commitment to teach young people the power of science.
The well-rounded education of human beings needs to include lessons learned both from a study of the physical world, and from a study of humanity.
Whether we are teachers or not, those of us who admire technology and innovation, and who wish to support progress, usually embrace the importance of educating the next generation of scientists and inventors. Growing a healthy technological civilization takes a lot of work, skill, and wisdom, and its continued health depends on future generations of competent thinkers. Thus, we may find it encouraging that there is currently an abundance of interest in STEM– the common acronym for the study of science, technology, engineering, and math.
But education is as challenging an endeavor as science itself. Educating youth--if we want to do it right--requires as much thought, work, and expertise as discovering a cure or pioneering regenerative medicine. Before we give our money, time, or support to any particular school or policy, let's give some thought to the details of the educational process.
A Well-Balanced Diet
For one thing, STEM education cannot stand in isolation. The well-rounded education of human beings needs to include lessons learned both from a study of the physical world, and from a study of humanity. This is especially true for the basic education of children, but it is true even for college students. And even for those in science and engineering, there are important lessons to be learned from the study of history, literature, and art.
Scientists have their own emotions and values, and also need financial support. The fruits of their labor ultimately benefit other people. How are we all to function together in our division-of-labor society, without some knowledge of the way societies work? How are we to fully thrive and enjoy life, without some understanding of ourselves, our motives, our moral values, and our relationships to others? STEM education needs the humanities as a partner. That flourishing civilization we dream of requires both technical competence and informed life-choices.
Think for Yourself (Even in Science)
Perhaps even more important than what is taught, is the subject of how things are taught. We want our children to learn the skill of thinking independently, but even in the sciences, we often fail completely to demonstrate how. Instead of teaching science as a thinking process, we indoctrinate, using the grand discoveries of the great scientists as our sacred texts. But consider the words of Isaac Newton himself, regarding rote learning:
A Vulgar Mechanick can practice what he has been taught or seen done, but if he is in an error he knows not how to find it out and correct it, and if you put him out of his road he is at a stand. Whereas he that is able to reason nimbly and judiciously about figure, force, and motion, is never at rest till he gets over every rub.
What's the point of all this formal schooling in the first place? Is it, as many of the proponents of STEM education might argue, to train students for a "good" career?
If our goal is to help students "reason nimbly" about the world around them, as the great scientists themselves did, are we succeeding? When we "teach" middle school students about DNA or cellular respiration by presenting as our only supporting evidence cartoon pictures, are we showing students a process of discovery based on evidence and hard work? Or are we just training them to memorize and repeat what the authorities say?
A useful education needs to give students the skill of following a line of reasoning, of asking rational questions, and of chewing things through in their minds--even if we regard the material as beyond question. Besides feeding students a well-balanced diet of knowledge, healthy schooling needs to teach them to digest this information thoroughly.
Thinking Training
Now step back for a moment and think about the purpose of education. What's the point of all this formal schooling in the first place? Is it, as many of the proponents of STEM education might argue, to train students for a "good" career? That view may have some validity for young adults, who are beginning to choose electives in favored subjects, and have started to choose a direction for their career.
But for the basic education of children, this way of thinking is presumptuous and disastrous. I would argue that the central purpose of a basic education is not to teach children how to perform this or that particular skill, but simply to teach them to think clearly. We should not be aiming to provide job training, but thinking training. We should be helping children learn how to "reason nimbly" about the world around them, and breathing life into their thinking processes, by which they will grapple with the events and circumstances of their lives.
So as we admire innovation, dream of a wonderful future, and attempt to nurture the next generation of scientists and engineers, instead of obsessing over STEM education, let us focus on rational education. Let's worry about showing children how to think--about all the important things in life. Let's give them the basic facts of human existence -- physical and humanitarian -- and show them how to fluently and logically understand them.
Some students will become the next generation of creators, and some will follow other careers, but together -- if they are educated properly -- they will continue to grow their inheritance, and to keep our civilization healthy and flourishing, in body and in mind.
Do New Tools Need New Ethics?
Scarcely a week goes by without the announcement of another breakthrough owing to advancing biotechnology. Recent examples include the use of gene editing tools to successfully alter human embryos or clone monkeys; new immunotherapy-based treatments offering longer lives or even potential cures for previously deadly cancers; and the creation of genetically altered mosquitos using "gene drives" to quickly introduce changes into the population in an ecosystem and alter the capacity to carry disease.
The environment for conducting science is dramatically different today than it was in the 1970s, 80s, or even the early 2000s.
Each of these examples puts pressure on current policy guidelines and approaches, some existing since the late 1970s, which were created to help guide the introduction of controversial new life sciences technologies. But do the policies that made sense decades ago continue to make sense today, or do the tools created during different eras in science demand new ethics guidelines and policies?
Advances in biotechnology aren't new of course, and in fact have been the hallmark of science since the creation of the modern U.S. National Institutes of Health in the 1940s and similar government agencies elsewhere. Funding agencies focused on health sciences research with the hope of creating breakthroughs in human health, and along the way, basic science discoveries led to the creation of new scientific tools that offered the ability to approach life, death, and disease in fundamentally new ways.
For example, take the discovery in the 1970s of the "chemical scissors" in living cells called restriction enzymes, which could be controlled and used to introduce cuts at predictable locations in a strand of DNA. This led to the creation of tools that for the first time allowed for genetic modification of any organism with DNA, which meant bacteria, plants, animals, and even humans could in theory have harmful mutations repaired, but also that changes could be made to alter or even add genetic traits, with potentially ominous implications.
The scientists involved in that early research convened a small conference to discuss not only the science, but how to responsibly control its potential uses and their implications. The meeting became known as the Asilomar Conference for the meeting center where it was held, and is often noted as the prime example of the scientific community policing itself. While the Asilomar recommendations were not sufficient from a policy standpoint, they offered a blueprint on which policies could be based and presented a model of the scientific community setting responsible controls for itself.
But the environment for conducting science changed over the succeeding decades and it is dramatically different today than it was in the 1970s, 80s, or even the early 2000s. The regime for oversight and regulation that has provided controls for the introduction of so-called "gene therapy" in humans starting in the mid-1970s is beginning to show signs of fraying. The vast majority of such research was performed in the U.S., U.K., and Europe, where policies were largely harmonized. But as the tools for manipulating humans at the molecular level advanced, they also became more reliable and more precise, as well as cheaper and easier to use—think CRISPR—and therefore more accessible to more people in many more countries, many without clear oversight or policies laying out responsible controls.
There is no precedent for global-scale science policy, though that is exactly what this moment seems to demand.
As if to make the point through news headlines, scientists in China announced in 2017 that they had attempted to perform gene editing on in vitro human embryos to repair an inherited mutation for beta thalassemia--research that would not be permitted in the U.S. and most European countries and at the time was also banned in the U.K. Similarly, specialists from a reproductive medicine clinic in the U.S. announced in 2016 that they had performed a highly controversial reproductive technology by which DNA from two women is combined (so-called "three parent babies"), in a satellite clinic they had opened in Mexico to avoid existing prohibitions on the technique passed by the U.S. Congress in 2015.
In both cases, genetic changes were introduced into human embryos that if successful would lead to the birth of a child with genetically modified germline cells—the sperm in boys or eggs in girls—with those genetic changes passed on to all future generations of related offspring. Those are just two very recent examples, and it doesn't require much imagination to predict the list of controversial possible applications of advancing biotechnologies: attempts at genetic augmentation or even cloning in humans, and alterations of the natural environment with genetically engineered mosquitoes or other insects in areas with endemic disease. In fact, as soon as this month, scientists in Africa may release genetically modified mosquitoes for the first time.
The technical barriers are falling at a dramatic pace, but policy hasn't kept up, both in terms of what controls make sense and how to address what is an increasingly global challenge. There is no precedent for global-scale science policy, though that is exactly what this moment seems to demand. Mechanisms for policy at global scale are limited–-think UN declarations, signatory countries, and sometimes international treaties, but all are slow, cumbersome and have limited track records of success.
But not all the news is bad. There are ongoing efforts at international discussion, such as an international summit on human genome editing convened in 2015 by the National Academies of Sciences and Medicine (U.S.), Royal Academy (U.K.), and Chinese Academy of Sciences (China), a follow-on international consensus committee whose report was issued in 2017, and an upcoming 2nd international summit in Hong Kong in November this year.
These efforts need to continue to focus less on common regulatory policies, which will be elusive if not impossible to create and implement, but on common ground for the principles that ought to guide country-level rules. Such principles might include those from the list proposed by the international consensus committee, including transparency, due care, responsible science adhering to professional norms, promoting wellbeing of those affected, and transnational cooperation. Work to create a set of shared norms is ongoing and worth continued effort as the relevant stakeholders attempt to navigate what can only be called a brave new world.