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.
Scientists: Don’t Leave Religious Communities Out in the Cold
[Editor's Note: This essay is in response to our current Big Question series: "How can the religious and scientific communities work together to foster a culture that is equipped to face humanity's biggest challenges?"]
I humbly submit that the question should be rephrased: How can the religious and scientific communities NOT work together to face humanity's biggest challenges? The stakes are higher than ever before, and we simply cannot afford to go it alone.
I believe in evolution -- the evolution of the relationship of science and religion.
The future of the world depends on our collaboration. I believe in evolution -- the evolution of the relationship of science and religion. Science and religion have lived in alternately varying relationships ranging from peaceful coexistence to outright warfare. Today we have evolved and have begun to embrace the biological relationship of mutualism. This is in part due to the advances in medicine and science.
Previous scientific discoveries and paradigm shifts precipitated varying theological responses. With Copernicus, we grappled with the relationship of the earth to the universe. With Darwin, we re-evaluated the relationship of man to the other creatures on earth. However, as theologically complex as these debates were, they had no practical relevance to the common man. Indeed, it was possible for people to live their entire lives happily without pondering these issues.
In the 21st century, the microscope is honing in further, with discoveries relating to the understanding of the very nature and composition of the human being, both body and mind/soul. Thus, as opposed to the past, the implications of the latest scientific advances directly affect the common man. The religious implications are not left to the ivory tower theologians. Regular people are now confronted with practical religious questions previously unimagined.
For example, in the field of infertility, if a married woman undergoes donor insemination, is she considered an adulteress? If a woman of one faith gestates the child of another faith, to whose faith does the child belong? If your heart is failing, can you avail yourself of stem cells derived from human embryos, or would you be considered an accomplice to murder? Would it be preferable to use artificially derived stem cells if they are available?
The implications of our current debates are profound, and profoundly personal. Science is the great equalizer. Every living being can potentially benefit from medical advances. We are all consumers of the scientific advances, irrespective of race or religion. As such, we all deserve a say in their development.
If the development of the science is collaborative, surely the contemplation of its ethical/religious applications should likewise be.
With gene editing, uterus transplants, head transplants, artificial reproductive seed, and animal-human genetic combinations as daily headlines, we have myriad ethical dilemmas to ponder. What limits should we set for the uses of different technologies? How should they be financed? We must even confront the very definition of what it means to be human. A human could receive multiple artificial transplants, 3D printed organs, genetic derivatives, or organs grown in animals. When does a person become another person or lose his identity? Will a being produced entirely from synthetic DNA be human?
In the Middle Ages, it was possible for one person to master all of the known science, and even sometimes religion as well, such as the great Maimonides. In the pre-modern era, discoveries were almost always attributed to one individual: Jenner, Lister, Koch, Pasteur, and so on. Today, it is impossible for any one human being to master medicine, let alone ethics, religion, etc. Advances are made not usually by one person but by collaboration, often involving hundreds, if not thousands of people across the globe. We cite journal articles, not individuals. Furthermore, the magnitude and speed of development is staggering. Add artificial intelligence and it will continue to expand exponentially.
If the development of the science is collaborative, surely the contemplation of its ethical/religious applications should likewise be. The issues are so profound that we need all genes on deck. The religious community should have a prominent seat at the table. There is great wisdom in the religious traditions that can inform contemporary discussions. In addition, the religious communities are significant consumers of, not to mention contributors to, the medical technology.
An ongoing dialogue between the scientific and religious communities should be an institutionalized endeavor, not a sporadic event, reactive to a particular discovery. The National Institutes of Health or other national organizations could provide an online newsletter designed for the clergy with a summary of the latest developments and their potential applications. An annual meeting of scientists and religious leaders could provide a forum for the scientists to appreciate the religious ramifications of their research (which may be none as well) and for the clergy to appreciate the rapidly developing fields of science and the implications for their congregants. Theological seminaries must include basic scientific literacy as part of their curricula.
We need the proper medium of mutual respect and admiration, despite healthy disagreement.
How do we create a "culture"? Microbiological cultures take time and require the proper medium for maximal growth. If one of the variables is altered, the culture can be affected. To foster a culture of continued successful collaboration between scientists and religious communities, we likewise need the proper medium of mutual respect and admiration, despite healthy disagreement.
The only way we can navigate these unchartered waters is through constant, deep and meaningful collaboration every single step of the way. By cultivating a mutualistic relationship we can inform, caution and safeguard each other to maximize the benefits of emerging technologies.
[Ed. Note: Don't miss the other perspectives in this Big Question series, from a science scholar and a Reverend/molecular geneticist.]
Why the Pope Should Officially Embrace Biotechnology
[Editor's Note: This essay is in response to our current Big Question series: "How can the religious and scientific communities work together to foster a culture that is equipped to face humanity's biggest challenges?"]
In May 2015, Pope Francis issued an encyclical with the subtitle "On Care for Our Common Home." The letter addressed various environmental issues, such as pollution and climate change, and it reminded all of us that we are to steward the Earth, not plunder it.
Without question, biotechnology has saved the lives of millions – perhaps billions – of people.
The Pope's missive demonstrates that he is both theologically sound and scientifically literate, a very rare combination. That is why he should now author an encyclical urging the world to embrace the life-giving promise of biotechnology.
Without question, biotechnology has saved the lives of millions – perhaps billions – of people. Arguably, vaccines were the most important invention in the history of mankind. It is thought that, in the 20th century alone, at least 300 million people were killed by smallpox. Today, the number is zero, thanks to vaccination. Other killers, such as measles, diphtheria, meningitis, and diarrhea, are kept at bay because of vaccines.
Biotechnology has also saved the lives of diabetics. At one time, insulin was extracted from pig pancreases, and there were fears that we would run out of it. Then, in the 1970s, crucial advances in biotechnology allowed for the gene that encodes human insulin to be expressed in bacteria. Today, diabetics can get extremely pure insulin thanks to this feat of genetic modification.
Likewise, genetic modification has improved the environment and the lives of farmers all over the world, none more so than those living in developing countries. According to a meta-analysis published in PLoS ONE, GMOs have "reduced chemical pesticide use by 37%, increased crop yields by 22%, and increased farmer profits by 68%."
Even better, GMOs also could help improve the lives of non-farmers. In poor parts of the world, malnutrition is still extremely common. People whose diets consist mostly of rice, for example, often suffer from vitamin A deficiency, which can lead to blindness. Golden Rice, which was genetically modified to contain a vitamin A precursor, was created and given away for free in an act of humanitarianism. Other researchers have created a genetically modified cassava to help combat iron and zinc deficiencies among children in Africa.
Despite these groundbreaking advances, the public is turning against biotechnology.
Biotechnology has also helped women with mitochondrial disease bear healthy children. Children inherit their mitochondria, the powerhouses of our cells, solely from their mothers. Mitochondrial defects can have devastating health consequences. Using what is colloquially called the "three-parent embryo technique," a healthy woman donates an egg. The nucleus of that egg is removed, and that of the mother-to-be is put in its place. Then, the egg is fertilized using conventional in vitro fertilization. In April 2016, the world's first baby was born using this technique.
Yet, despite these groundbreaking advances, the public is turning against biotechnology. Across America and Europe, anti-vaccine activists have helped usher in a resurgence of entirely preventable diseases, such as measles. Anti-GMO activists have blocked the implementation of Golden Rice. And other activists decry reproductive technology as "playing God."
Nonsense. These technologies improve overall welfare and save lives. Those laudable goals are shared by all the world's major religions as part of their efforts to improve the human condition. That is why it is vitally important, if science is to succeed in eradicating illness, that it gets a full-throated endorsement from powerful religious leaders.
In his 2015 encyclical, Pope Francis wrote:
Any technical solution which science claims to offer will be powerless to solve the serious problems of our world if humanity loses its compass, if we lose sight of the great motivations which make it possible for us to live in harmony, to make sacrifices and to treat others well.
He is correct. Indeed, when people are protesting life-saving vaccines, we have lost not only our moral compass but our intellect, too.
Imagine the impact he could have if Pope Francis issued an encyclical titled "On Protecting Our Most Vulnerable." He could explain that some children, stricken with cancer or suffering from an immunological disease, are unable to receive vaccines. Therefore, we all have a moral duty to be vaccinated in order to protect them through herd immunity.
Or imagine the potential impact of an encyclical titled "On Feeding the World," in which the Pope explained that rich countries have an obligation to poorer ones to feed them by all means necessary, including the use of biotechnology. If Muslim, Buddhist, and Hindu scholars throughout Asia and Africa also embraced the message, its impact could be multiplied.
In order to be successful, science needs religion; in order to be practical, religion needs science.
In order to be successful, science needs religion; in order to be practical, religion needs science.
Unfortunately, in discussions of the relationship between science and religion, we too often focus on the few areas in which they conflict. But this misses a great opportunity. By combining technological advances with moral authority, science and religion can work together to save the world.
[Ed. Note: Don't miss the other perspectives in this Big Question series, from a Rabbi/M.D. and a Reverend/molecular geneticist.]