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.
How Should Genetic Engineering Shape Our Future?
Terror. Error. Success. These are the three outcomes that ethicists evaluating a new technology should fear. The possibility that a breakthrough might be used maliciously. The possibility that newly empowered scientists might make a catastrophic mistake. And the possibility that a technology will be so successful that it will change how we live in ways that we can only guess—and that we may not want.
These tools will allow scientists to practice genetic engineering on a scale that is simultaneously far more precise and far more ambitious than ever before.
It was true for the scientists behind the Manhattan Project, who bequeathed a fear of nuclear terror and nuclear error, even as global security is ultimately defined by these weapons of mass destruction. It was true for the developers of the automobile, whose invention has been weaponized by terrorists and kills 3,400 people by accident each day, even as the more than 1 billion cars on the road today have utterly reshaped where we live and how we move. And it is true for the researchers behind the revolution in gene editing and writing.
Put simply, these tools will allow scientists to practice genetic engineering on a scale that is simultaneously far more precise and far more ambitious than ever before. Editing techniques like CRISPR enable exact genetic repairs through a simple cut and paste of DNA, while synthetic biologists aim to redo entire genomes through the writing and substitution of synthetic genes. The technologies are complementary, and they herald an era when the book of life will be not just readable, but rewritable. Food crops, endangered animals, even the human body itself—all will eventually be programmable.
The benefits are easy to imagine: more sustainable crops; cures for terminal genetic disorders; even an end to infertility. Also easy to picture are the ethical pitfalls as the negative images of those same benefits.
Terror is the most straightforward. States have sought to use biology as a weapon at least since invading armies flung the corpses of plague victims into besieged castles. The 1975 biological weapons convention banned—with general success—the research and production of offensive bioweapons, though a handful of lone terrorists and groups like the Oregon-based Rajneeshee cult have still carried out limited bioweapon attacks. Those incidents ultimately caused little death and damage, in part because medical science is mostly capable of defending us from those pathogens that are most easily weaponized. But gene editing and writing offers the chance to engineer germs that could be far more effective than anything nature could develop. Imagine a virus that combines the lethality of Ebola with the transmissibility of the common cold—and in the new world of biology, if you can imagine something, you will eventually be able to create it.
The benefits are easy to imagine: more sustainable crops; cures for terminal genetic disorders; even an end to infertility. Also easy to picture are the ethical pitfalls.
That's one reason why James Clapper, then the U.S. director of national intelligence, added gene editing to the list of threats posed by "weapons of mass destruction and proliferation" in 2016. But these new tools aren't merely dangerous in the wrong hands—they can also be dangerous in the right hands. The list of labs accidents involving lethal bugs is much longer than you'd want to know, at least if you're the sort of person who likes to sleep at night. The U.S. recently lifted a ban on research that works to make existing pathogens, like the H5N1 avian flu virus, more virulent and transmissible, often using new technologies like gene editing. Such work can help medicine better prepare for what nature might throw at us, but it could also make the consequences of a lab error far more catastrophic. There's also the possibility that the use of gene editing and writing in nature—say, by CRISPRing disease-carrying mosquitoes to make them sterile—could backfire in some unforeseen way. Add in the fact that the techniques behind gene editing and writing are becoming simpler and more automated with every year, and eventually millions of people will be capable—through terror or error—of unleashing something awful on the world.
The good news is that both the government and the researchers driving these technologies are increasingly aware of the risks of bioterror and error. One government program, the Functional Genomic and Computational Assessment of Threats (Fun GCAT), provides funding for scientists to scan genetic data looking for the "accidental or intentional creation of a biological threat." Those in the biotech industry know to keep an eye out for suspicious orders—say, a new customer who orders part of the sequence of the Ebola or smallpox virus. "With every invention there is a good use and a bad use," Emily Leproust, the CEO of the commercial DNA synthesis startup Twist Bioscience, said in a recent interview. "What we try hard to do is put in place as many systems as we can to maximize the good stuff, and minimize any negative impact."
But the greatest ethical challenges in gene editing and writing will arise not from malevolence or mistakes, but from success. Through a new technology called in vitro gametogenesis (IVG), scientists are learning how to turn adult human cells like a piece of skin into lab-made sperm and egg cells. That would be a huge breakthrough for the infertile, or for same-sex couples who want to conceive a child biologically related to both partners. It would also open the door to using gene editing to tinker with those lab-made embryos. At first interventions would address any obvious genetic disorders, but those same tools would likely allow the engineering of a child's intelligence, height and other characteristics. We might be morally repelled today by such an ability, as many scientists and ethicists were repelled by in-vitro fertilization (IVF) when it was introduced four decades ago. Yet more than a million babies in the U.S. have been born through IVF in the years since. Ethics can evolve along with technology.
These new technologies offer control over the code of life, but only we as a society can seize control over where these tools will take us.
Fertility is just one human institution that stands to be changed utterly by gene editing and writing, and it's a change we can at least imagine. As the new biology grows more ambitious, it will alter society in ways we can't begin to picture. Harvard's George Church and New York University's Jef Boeke are leading an effort called HGP-Write to create a completely synthetic human genome. While gene editing allows scientists to make small changes to the genome, the gene synthesis that Church and his collaborators are developing allows for total genetic rewrites. "It's a difference between editing a book and writing one," Church said in an interview earlier this year.
Church is already working on synthesizing organs that would be resistant to viruses, while other researchers like Harris Wang at Columbia University are experimenting with bioengineering mammalian cells to produce nutrients like amino acids that we currently need to get from food. The horizon is endless—and so are the ethical concerns of success. What if parents feel pressure to engineer their children just so they don't fall behind their IVG peers? What if only the rich are able to access synthetic biology technologies that could make them stronger, smarter and longer lived? Could inequality become encoded in the genome?
These are questions that are different from the terror and errors fears around biosecurity, because they ask us to think hard about what kind of future we want. To their credit, Church and his collaborators have engaged bioethicists from the start of their work, as have the pioneers behind CRISPR. But the challenges coming from successful gene editing and writing are too large to be outsourced to professional ethicists. These new technologies offer control over the code of life, but only we as a society can seize control over where these tools will take us.
Is Red Tape Depriving Patients of Life-Altering Therapies?
Rich Mancuso suffered from herpes for most of his adult life. The 49-year-old New Jersey resident was miserable. He had at least two to three outbreaks every month with painful and unsightly sores on his face and in his eyes, yet the drugs he took to control the disease had terrible side effects--agonizing headaches and severe stomach disturbances.
Last week, the FDA launched a criminal investigation to determine whether the biotech behind the vaccine had violated regulations.
So in 2016, he took an unusual step: he was flown to St. Kitt's, an island in the West Indies, where he participated in a clinical trial of a herpes vaccine, and received three injections of the experimental therapeutic during separate visits to the island. Within a year, his outbreaks stopped. "Nothing else worked," says Mancuso, who feels like he's gotten his life back. "And I've tried everything on the planet."
Mancuso was one of twenty genital herpes sufferers who were given the experimental vaccine in tests conducted on the Caribbean island and in hotel rooms near the campus of Southern Illinois University in Springfield where the vaccine's developer, microbiologist William Halford, was on the faculty. But these tests were conducted under the radar, without the approval or safety oversight of the Food and Drug Administration or an institutional review board (IRB), which routinely monitor human clinical trials of experimental drugs to make sure participants are protected.
Last week, the FDA launched a criminal investigation to determine whether anyone from SIU or Rational Vaccines, the biotech behind the vaccine, had violated regulations by aiding Halford's research. The SIU scientist was a microbiologist, not a medical doctor, which means that volunteers were not only injected with an unsanctioned experimental treatment but there wasn't even routine medical oversight.
On one side are scientists and government regulators with legitimate safety concerns....On the other are desperate patients and a dying scientist willing to go rogue in a foreign country.
Halford, who was stricken with a rare form of a nasal cancer, reportedly bypassed regulatory rules because the clock was ticking and he wanted to speed this potentially life-altering therapeutic to patients. "There was no way he had enough time to raise $100 million to test the drugs in the U.S.," says Mancuso, who became friends with Halford before he died in June of 2017 at age 48. "He knew if he didn't do something, his work would just die and no one would benefit. This was the only way."
But was it the only way? Once the truth about the trial came to light, public health officials in St. Kitt's disavowed the trial, saying they had not been notified that it was happening, and Southern Illinois University's medical school launched an investigation that ultimately led to the resignation of three employees, including a faculty member, a graduate student and Halford's widow. Investors in Rational Vaccines, including maverick Silicon Valley billionaire Peter Thiel, demanded that all FDA rules must be followed in future tests.
"Trials have to yield data that can be submitted to the FDA, which means certain requirements have to be met," says Jeffrey Kahn, a bioethicist at Johns Hopkins University in Baltimore. "These were renegade researchers who exposed people to unnecessary risks, which was hugely irresponsible. I don't know what they expected to do with the research. It was a waste of money and generated data that can't be used because no regulator would accept it."
But this story illuminates both sides of a thorny issue. On one side are scientists and government regulators with legitimate safety concerns who want to protect volunteers from very real risks—people have died even in closely monitored clinical trials. On the other, are desperate patients and a dying scientist willing to go rogue in a foreign country where there is far less regulatory scrutiny. "It's a balancing act," says Jennifer Miller, a medical ethicist at New York University and president of Bioethics International. "You really need to protect participants but you also want access to safe therapies."
"Safety is important, but being too cautious kills people, too—allowing them to just die without intervention seems to be the biggest harm."
This requirement—that tests show a drug is safe and effective before it can win regulatory approval--dates back to 1962, when the sedative thalidomide was shown to have caused thousands of birth defects in Europe. But clinical trials can be costly and often proceed at a glacial pace. Typically, companies shell out more than $2.5 billion over the course of the decade it normally takes to shepherd a new treatment through the three phases of testing before it wins FDA approval, according to a 2014 study by the Tufts Center for the Study of Drug Development. Yet only 11.8 percent of experimental therapies entering clinical tests eventually cross the finish line.
The upshot is that millions can suffer and thousands of people may die awaiting approvals for life saving drugs, according to Elizabeth Parrish, the founder and CEO of BioViva, a Seattle-based biotech that aims to provide data collection platforms to scientists doing overseas tests. "Going offshore to places where it's legal to take a therapeutic can created expedited routes for patients to get therapies for which there is a high level of need," she says. "Safety is important, but being too cautious kills people, too—allowing them to just die without intervention seems to be the biggest harm."
Parrish herself was frustrated with the slow pace of gene therapy trials; scientists worried about the risks associated with fixing mutant DNA. To prove a point, she traveled to a clinic in Colombia in 2015 where she was injected with two gene therapies that aim to improve muscle function and lengthen telomeres, the caps on the end of chromosomes that are linked to aging and genetic diseases. Six months later, the therapy seemed to have worked—her muscle mass had increased and her telomeres had grown by 9 percent, the equivalent of turning back 20 years of aging, according to her own account. Yet the treatments are still unavailable here in the U.S.
In the past decade, Latin American countries like Columbia, and Mexico in particular, have become an increasingly attractive test destination for multi-national drug companies and biotechs because of less red tape.
In the past decade, Latin American countries like Columbia, and Mexico in particular, have become an increasingly attractive test destination for multi-national drug companies and biotechs because of less red tape around testing emerging new science, like gene therapies or stem cells. Plus, clinical trials are cheaper to conduct, it's easier to recruit volunteers, especially ones who are treatment naïve, and these human tests can reveal whether local populations actually respond to a particular therapy. "We do have an exhaustive framework for running clinical trials that are aligned with international requirements," says Ernesto Albaga, an attorney with Hogan Lovells in Mexico City who specializes in the life sciences. "But our environment is still not as stringent as it is in other places, like the U.S."
The fact is American researchers are increasingly testing experimental drugs outside of the U.S., although virtually all of them are monitored by local scientists who serve as co-investigators. In 2017 alone, more than 86 percent of experimental drugs seeking FDA approval have been tested, at least in part, in foreign countries, like Mexico, China, Russia, Poland and South Africa, according to an analysis by STAT. However, in places without strict oversight, such as Russia and Georgia, results may be fraudulent, according to one 2017 report in the New England Journal of Medicine. And in developing countries, the poor can become guinea pigs. In the early 2000s, for example, a test in Uganda of an AIDS drug resulted in thousands of unreported serious adverse reactions and 14 deaths; in India, eight volunteers died during a test of the anti-clotting drug, Streptokinase—and test subjects didn't even know they were part of a clinical trials.
Still, "the world is changing," concludes Dr. Jennifer Miller of NYU. "We need to figure out how to get safe and effective drugs to patients more quickly without sacrificing too much protection."