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.
We all know the typical astronaut accessories—the EVA suit, the oxygen tanks, the radio assembly. But there's an invisible part of each space mission that's often overlooked: the trillions of microorganisms that hitch a ride.
Observing responses of pathogens in space could help scientists figure out how to outsmart them when they cause trouble on Earth.
Dr. Sarah Wallace is a NASA microbiologist who aims to keep microbes from causing problems for U.S. astronauts aboard the International Space Station. According to Wallace, research on microorganisms in space has more than cosmic importance. It can also reveal things about our health here on Earth:
1) Avoiding disease isn't all about maintaining a sterile environment.
NASA has a great track record of keeping the crew healthy on space missions. But surprisingly, it's not from having kept the space flight environment as sterile as possible.
Wallace says, "We [monitor] the environment but unless we find something that's medically significant, or [in] super high numbers, we're not going to do anything."
Not only is it impossible for astronauts to live in completely sterile quarters—crew members, after all, are microbe-shedding machines—but it may not even be desirable, given what we now know about the human microbiome. Scientists have found that the entire community of microorganisms (bacteria, archaea, fungi, and viruses) living in and on us likely have an active role in keeping us healthy. This means that down on the ground we need to let go of the germophobe idea that eradicating all microbes is always better for our health.
2) Disease-causing microbes change their behavior under different conditions.
Remember the recent E. coli O157:H7 outbreak linked to romaine lettuce? We're still grappling with a lot of pathogen problems here on Earth. One reason is that scientists are still learning which strategies these disease-causing microorganisms are capable of employing under different conditions.
Space missions are associated with a major shift in gut microbiome composition—as shown in NASA's twin study.
Wallace says experiments with Salmonella Typhimurium showed that the pathogen became more virulent in space. Yet curiously, the opposite seemed to happen to Staphylococcus aureus under space-flight-like conditions—it became more benign.
"The way these organisms have evolved, certain triggers [in the space flight environment] might be dictating how they're responding," Wallace says.
Observing these responses could help scientists figure out how to outsmart the pathogen when it causes trouble on Earth. "It's giving us some great insights into how we could target them differently in the future," she explains.
3) Major shifts in the gut microbiome could affect health in specific ways.
Scientists still have a lot to learn about which changes in an adult's gut microbiome actually cause a change in health status. In fact, microbiome-focused therapeutics companies are in hot pursuit of these connections.
Space missions are associated with a major shift in gut microbiome composition—as shown in NASA's twin study, which followed astronaut Scott Kelly during a year aboard the ISS while his identical twin brother Mark (a retired astronaut) stayed on the ground. Scott experienced simultaneous changes in telomere length and bone formation; were these related to the gut microbial differences?
Wallace says a soon-to-be-published study of nine additional astronauts could help answer this question. The research may reveal how closely gut microbiome shifts track health outcomes, and the reversibility of the changes.
She emphasizes the science from her lab isn't meant to help only the small minority of humans who will ever go to space: "That's always our goal—that our research is helping people on Earth."
Today's growing distrust of science is not an academic problem. It can be a matter of life and death.
Take, for example, the tragic incident in 2016 when at least 10 U.S. children died and over 400 were sickened after they tried homeopathic teething medicine laced with a poisonous herb called "deadly nightshade." Carried by CVS, Walgreens, and other major American pharmacies, the pills contained this poison based on the alternative medicine principle of homeopathy, the treatment of medical conditions by tiny doses of natural substances that produce symptoms of disease.
Such "alternative medicines" take advantage of the lack of government regulation and people's increasing hostility toward science.
These children did not have to die. Numerous research studies show that homeopathy does not work. Despite this research, homeopathy is a quickly-growing multi-billion dollar business.
Such "alternative medicines" take advantage of the lack of government regulation and people's increasing hostility toward science. Polling shows that the number of people who believe that science has "made life more difficult" increased by 50 percent from 2009 to 2015. According to a 2017 survey, only 35 percent of respondents have "a lot" of trust in scientists; the number of people who do "not at all" trust scientists increased by over 50 percent from a similar poll conducted in December 2013.
Children dying from deadly nightshade is only one consequence of this crisis of trust. For another example, consider the false claim that vaccines cause autism. This belief has spread widely across the US, and led to a host of problems. For instance, measles was practically eliminated in the US by 2000. However, in recent years outbreaks of measles have been on the rise, driven by parents failing to vaccinate their children in a number of communities.
The Internet Is for… Misinformation
The rise of the Internet, and more recently social media, is key to explaining the declining public confidence in science.
Before the Internet, the information accessible to the general public about any given topic usually came from experts. For instance, researchers on autism were invited to talk on mainstream media, they wrote encyclopedia articles, and they authored books distributed by large publishers.
The Internet has enabled anyone to be a publisher of content, connecting people around the world with any and all sources of information. On the one hand, this freedom is empowering and liberating, with Wikipedia a great example of a highly-curated and accurate source on the vast majority of subjects. On the other, anyone can publish a blog piece making false claims about links between vaccines and autism or the effectiveness of homeopathic medicine. If they are skilled at search engine optimization, or have money to invest in advertising, they can get their message spread widely. Russia has done so extensively to influence elections outside of its borders, whether in the E.U. or the U.S.
Unfortunately, research shows that people lack the skills for differentiating misinformation from true information. This lack of skills has clear real-world effects: U.S. adults believed 75 percent of fake news stories about the 2016 US Presidential election. The more often someone sees a piece of misinformation, the more likely they are to believe it.
To make matters worse, we all suffer from a series of thinking errors such as the confirmation bias, our tendency to look for and interpret information in ways that conform to our intuitions.
Blogs with falsehoods are bad enough, but the rise of social media has made the situation even worse. Most people re-share news stories without reading the actual article, judging the quality of the story by the headline and image alone. No wonder research has indicated that misinformation spreads as much as 10 times faster and further on social media than true information. After all, creators of fake news are free to devise the most appealing headline and image, while credible sources of information have to stick to factual headlines and images.
To make matters worse, we all suffer from a series of thinking errors such as the confirmation bias, our tendency to look for and interpret information in ways that conform to our intuitions and preferences, as opposed to the facts. Our inherent thinking errors combined with the Internet's turbine power has exploded the prevalence of misinformation.
So it's no wonder we see troubling gaps between what scientists and the public believe about issues like climate change, evolution, genetically modified organisms, and vaccination.
What Can We Do?
Fortunately, there are proactive steps we can take to address the crisis of trust in science and academia. The Pro-Truth Pledge, founded by a group of behavioral science experts (including myself) and concerned citizens, calls on public figures, organizations, and private citizens to commit to 12 behaviors listed on the pledge website that research in behavioral science shows correlate with truthfulness.
Signers are held accountable through a crowdsourced reporting and evaluation mechanism while getting reputational rewards because of their commitment. The scientific consensus serves as a key measure of credibility, and the pledge encourages pledge-takers to recognize the opinions of experts - especially scientists - as more likely to be true when the facts are disputed.
The pledge "really does seem to change one's habits," encouraging signers to have attitudes "of honesty and moral sincerity."
Launched in December 2016, the pledge has surprising traction. Over 6200 private citizens took the pledge. So did more than 500 politicians, including members of US state legislatures Eric Nelson (PA), James White (TX), and Ogden Driskell (WY), and national politicians such as members of U.S. Congress Beto O'Rourke (TX), Matt Cartwright (PA), and Marcia Fudge (OH). Over 700 other public figures, such as globally-known public intellectuals Peter Singer, Steven Pinker, Michael Shermer, and Jonathan Haidt, took the pledge, as well as 70 organizations such as Media Bias/Fact Check, Fugitive Watch, Earth Organization for Sustainability, and One America Movement.
The pledge is effective in changing behaviors. A candidate for Congress, Michael Smith, took the Pro-Truth Pledge. He later posted on his Facebook wall a screenshot of a tweet by Donald Trump criticizing minority and disabled children. However, after being called out that the tweet was a fake, he went and searched Trump's feed. He could not find the original tweet, and while Trump may have deleted it, the candidate edited his own Facebook post to say, "Due to a Truth Pledge I have taken, I have to say I have not been able to verify this post." He indicated that he would be more careful with future postings.
U.S. Army veteran and pledge-taker John Kirbow described how the pledge "really does seem to change one's habits," helping push him both to correct his own mistakes with an "attitude of humility and skepticism, and of honesty and moral sincerity," and also to encourage "friends and peers to do so as well."
His experience is confirmed by research on the pledge. Two research studies at Ohio State University demonstrated the effectiveness of the pledge in changing the behavior of pledge-takers to be more truthful with a strong statistical significance.
Taking the pledge yourself, and encouraging people you know and your elected representatives to do the same, is an easy and effective way to fight misinformation and to promote a culture that values the truth.