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.
[Editor's Note: This is the final video of a five-part series titled "The Future Is Now: The Revolutionary Power of Stem Cell Research." Produced in partnership with the Regenerative Medicine Foundation, and filmed at the annual 2019 World Stem Cell Summit, this series illustrates how stem cell research will profoundly impact human life.]
Kira Peikoff was the editor-in-chief of Leaps.org from 2017 to 2021. As a journalist, her work has appeared in The New York Times, Newsweek, Nautilus, Popular Mechanics, The New York Academy of Sciences, and other outlets. She is also the author of four suspense novels that explore controversial issues arising from scientific innovation: Living Proof, No Time to Die, Die Again Tomorrow, and Mother Knows Best. Peikoff holds a B.A. in Journalism from New York University and an M.S. in Bioethics from Columbia University. She lives in New Jersey with her husband and two young sons. Follow her on Twitter @KiraPeikoff.
The Troubling Reason I Obsessively Researched My Pregnancy
At the end of my second trimester of pregnancy, I answered a call from an unknown number.
To be pregnant is to exist on a never-ending receiving line of advice, whether we want it or not.
"I know your due date is approaching," said a stranger at the other end of the line, completely freaking me out. She identified herself as being from Natera, a company that my doctor had used for genetic testing I had consented to months ago.
"Excuse me?" I said.
"Have you considered cord-blood banking?" she said.
"No, I'm not doing that," I said. I had read enough about cord-blood banking, the process of saving stem cell-containing blood from your baby's umbilical cord, to understand that my family was in the vast majority of those that would with extremely high likelihood derive no medical benefit from it. Of course, in the societally sanctioned spending spree that accompanies new parenthood, plenty of companies are happy to charge anyone hundreds if not thousands of dollars plus annual storage fees to collect and manage your cord blood.
"Why not? Have you considered all the bene—"
"I'm not doing it and I don't want to explain my decision," I said before hanging up. I would later learn I neglected to check a miniscule box on my testing consent forms at the doctor to opt out of solicitations. Still, I was angry that I was being telemarketed unnecessary and costly medical services by someone who had been trained to immediately call my judgment into question. I was annoyed that my doctor's office would allow such intrusions at all. When I asked my OB about it at my next visit, she told me there's no way Natera would have gotten my information from them. Apparently even she didn't realize what was on those forms.
The incident with Natera did nothing to heighten my trust of the medical establishment during my pregnancy. I was hardly alone. Almost every mom I knew had expressed a similar sentiment.
"I don't trust doctors," read the text of a loved one when I told her I would probably get an epidural after my doctor recommended getting one because, she said, it can help relax the pelvic muscles during labor. But this friend, a highly educated woman who had had done her research and had two unmedicated births, believed firmly otherwise. "Look it up," she said. Thus commenced more of the furious Googling I found myself doing multiple times a day since deciding I wanted to become pregnant.
To be pregnant is to exist on a never-ending receiving line of advice, whether we want it or not. Information presents to us from Google's never-out-of-reach search bar, friends and family eager to use our pregnancies as an excuse to recall their own, and the doctor's office, where the wisdom of medical professionals neatly comingles with brochures and free samples from myriad companies that would really, really like our business as new moms. Separating the "good" advice from the rest is a Herculean task that many pregnant women manage only with vigorous fact-finding missions of their own.
The medical community in America is poorly equipped to help women navigate the enormous pressures that come with birth and transitioning to motherhood.
Doing my research during pregnancy felt like a defense against the scary unknowns, overabundance of opinions, and disturbing marketing schemes that come with entering parenthood. The medical community in America is poorly equipped to help women navigate the enormous emotional and societal pressures that come with birth and transitioning to motherhood. Too much of what pregnant women experience at the doctor has to do with dated ideas about our care, mandated by tradition or a fear of being sued rather than medical necessity. These practices, like weigh-ins at every appointment or medically unnecessary C-sections (which are estimated to account, horrifically, for almost 50 percent of all C-sections performed in the U.S.), only heighten anxiety.
Meanwhile, things that might alleviate stress – like having thorough discussions about the kinds of interventions we might be asked to accept at the hospital during labor and delivery – are left to outside educators and doulas that insurance plans typically don't cover. The net effect isn't better health outcomes for mom and baby, but rather a normalized sense of distrust many American women feel toward their OBGYNs, and the burden of going to every appointment and the delivery room on the defensive. Instead of being wed to dated medical practices and tangled in America's new motherhood industrial complex, shouldn't our doctors, of all people, be our biggest advocates?
As soon as I found out I was pregnant, I devoured Expecting Better, by Emily Oster, an economist who embarked on her own fact-finding mission during her first pregnancy, predicated on the belief that the advice OBGYNs have been giving pregnant women for decades is out of date and unnecessarily restrictive. The book includes controversial stances, like that having small amounts of alcohol while pregnant is OK. (More recent research has called this view into question.) Oster writes that for the vast majority of pregnant women, it's perfectly fine to lie on your back, do sit-ups, and eat Brie — all things I was relieved to learn I wouldn't have to give up for nine months, despite the traditional advice, which my doctor also gave to me.
Oster recommends hiring a doula, based both on research and personal experience. It's a worthwhile investment for those who can afford it: according to one study, 20.4 percent of laboring women with doulas had C-sections compared with 34.2 percent of women without them. A doula can do many things for a pregnant client, including helping her write a birth plan, massaging her back in labor, and cheering her on, which is especially useful for women who plan to labor without pain medication. Use of doulas is on the rise; according to DONA International, the world's largest and oldest doula association, the number of doulas who have been certified to date is over 12,000, up from 2,000 in 2002.
But the most significant role a doula plays is that of patient advocate in the hospital. This is a profound commentary on the way the medical establishment handles childbirth, a medical event that 86 percent of women aged 40 to 44 had gone through as of 2016. Recognizing the maternal mortality crisis in the U.S., where women are far more likely to die as a result of childbirth than anywhere else in the developed world and black women are three times more likely to die in childbirth than white women, a few states now allow Medicaid to cover doulas. Can you imagine feeling the need to hire an independent non-medical care provider to help you run interference with your doctors and nurses for something like an appendectomy?
I wouldn't have been aware of all the imminent interventions during my labor if my doula hadn't told me about them. Things happen fast in the hospital and doctors and nurses may rush patients to consent before proceeding with things like breaking their water or hooking them up to an IV of Pitocin. Only because my husband and I had spent six hours in birth class — a suggestion by my doula — did I realize that I was empowered to say "no" to such procedures.
Expecting more trustworthy advice to come from my doctor than books or Google or even a doula hardly seems unreasonable.
Of course, we all feel immense pressure to become good parents, and questioning conventional medical wisdom is a natural response to that pressure. "Looking around at the world and saying, who am I as a parent? What is important to me? Who are the wise people? What do I think wisdom is? What is a good decision? If you're a certain type of introspective person, if you're really asking those questions, that's going to include like taking a second look at things that doctors, for example, say," says Koyuki Smith, a doula and birth educator.
Expecting more trustworthy advice to come from my doctor than books or Google or even a doula hardly seems unreasonable. Yet my doctor's office seemed more concerned with checking off a list of boxes rather than providing me with personalized care that might have relieved my understandable anxiety about my first birth. When I still hadn't gone into labor around the time of my due date, my doctor encouraged me to be induced because my baby appeared to be large. I declined but scheduled an induction to "hold my spot" around the 42-week mark.
When I asked what medication would be used for an induction if I had one and she said Cytotec, I told her I had read that drug could cause serious complications, but she dismissed my concerns after I told her they stemmed from a book I read on natural childbirth. The FDA's page on Cytotec isn't exactly reassuring.
The nurse who took me in triage after I went into labor a week past my due date practically scolded me for waiting to go into labor naturally instead of opting for induction sooner. My doula told her while I was struggling to speak through labor pains to get off my case about it. I hadn't even become a mom and I was already doing so many things "wrong." Because I had done my own reading, I felt confident that my choices weren't harming my baby or me.
Becoming a mom would be less daunting if the medical community found a way to help women navigate the pressures of motherhood instead of adding to them. "Our culture at large doesn't support women enough in the complicated emotions that are a part of this process," said Alexandra Saks, a reproductive psychologist and author of What No One Tells You: A Guide to Your Emotions From Pregnancy to Motherhood. "I hope that every practitioner that works with women around reproductive health prioritizes her emotions around her experience."
For many of us, that will mean doctors who help us understand the pros and cons of conventional advice, don't use their offices as marketing channels, and don't pressure women into medically unnecessary inductions. Moms should also receive more attention after delivery both in the hospital and after they get home; a single, quick postpartum visit at six weeks is not an adequate way to care for women recovering from the trauma of childbirth, nor is it an adequate way to ensure women are emotionally supported during the transition. While several people interrogated me about my mental health at the hospital and my doctor's office just before and after birth, if I had been concerned about postpartum depression, I can't imagine feeling comfortable enough in those moments to tell strangers filling out obligatory worksheets.
It also means figuring out how to talk to patients who are prone to Googling their pregnancies with gusto every single day. It would be impossible for many women to shun independent research during pregnancy altogether. But it would also be nice if our doctors didn't add to our impulse to do it.