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.
The Ethics of Navigating Teen Gender Transitions
At first, Miriam Zachariah's teenage nephew Theo, who was born female, came out as gay. But he "presented as very gender fluid," she says, which suggested that he hadn't made "a clear choice one way or another."
Families, physicians, and psychologists have pondered whether it's better, neutral, or worse to postpone gender transitions until adulthood.
Zachariah decided to ask her nephew, "Do you think you might be trans?" While he answered "no," the question "broke something open for him," she recalls.
A month later, at age 13, he began identifying as trans. And at 14 1/2, he started undergoing gender transition with an endocrine-blocking injection. More recently, at age 16, he added testosterone injections, and soon he won't need the endocrine blocker any longer.
"His voice is deepening, and his muscle mass is growing," says Zachariah, a principal of two elementary schools in Toronto who became her nephew's legal guardian while he was starting to transition.
There are many medical and bioethical aspects associated with the transition to one's self-identified gender, especially when the process involves children and adolescents. Families, physicians, and psychologists have pondered whether it's better, neutral, or worse to postpone the transition until adulthood, while remaining cognizant of the potential consequences to puberty suppression with cross-sex hormones and the irreversibility of transgender surgeries.
Studies have found a higher prevalence of mental health issues among transgender and gender nonconforming youth, particularly if they are unable to express themselves in the self-identified gender. Research also has shown that transgender adults in the process of transitioning initially experienced worse mental health problems than their adolescent counterparts.
The Endocrine Society, a professional medical organization that provides recommendations for clinical practice, stipulates in its guidelines that the diagnosis of gender identity be limited to qualified mental health professionals for those under age 18. This is important because children are still evolving in their thought processes and capacity to articulate themselves, says endocrinologist Joshua Safer, inaugural executive director of the Center for Transgender Medicine and Surgery at the Icahn School of Medicine at Mount Sinai in New York.
A transition can begin safely in gradations, by allowing young children to experiment with haircuts and clothes of either gender before puberty. "If it just ends up being a stage of life, we haven't done anything permanent," says Safer, who is president of the United States Professional Association for Transgender Health as well as steering committee co-chair of TransNet, the international transgender research consortium.
After changes in appearance, the next step would be to try puberty blockers. Also used to halt precocious puberty, the injections are "a reasonably established intervention" for transgender youth, although there are some concerns that the drugs could interfere with bone health in the future, he says.
From a mental health standpoint, "hormones for youth who qualify for them have offered a tremendous boost in well-being and also a reduction in anxiety, depression, and suicidality that often plague transgender youth when they experience their bodies as totally discordant with their self-knowledge of their authentic gender," says psychologist Diane Ehrensaft, director of mental health in the Child and Adolescent Gender Center at Benioff Children's Hospital of the University of California at San Francisco.
Many of these youth have either known about or have been living in their authentic gender since early childhood; others discovered their true identities in adolescence, often with the onset of puberty, says Ehrensaft, associate professor of pediatrics. The effects of gender-affirming hormone treatments are at least partially reversible, she adds, whereas surgical procedures are irreversible. Regardless of reversibility, best practices include careful consideration of all interventions to ensure they are in a youth's best interests in promoting gender health and general well-being.
When a child exhibits signs of gender dysphoria, parents and guardians should at a minimum take these feelings seriously.
In determining readiness for a transgender operation, an assessment of maturity is as important as chronological age, says Loren Schechter, plastic surgeon and director of the Center for Gender Confirmation Surgery at Weiss Memorial Hospital in Chicago. With the consent of a parent or guardian, he commonly performs mastectomies on adolescents at age 17 and sometimes earlier, based on the clinical circumstances and along with a multidisciplinary team that includes a primary care provider and a mental health professional.
"Typically, before surgery, people have had the opportunity and time to consider their options," Schechter says, observing that "the incidence of regret or changing one's mind is extremely low." Others may opt to transition socially but not surgically. "We recognize that gender is not binary," he explains. Some individuals may not "discreetly fit into male or female" in how they perceive themselves.
When a child exhibits signs of gender dysphoria, parents and guardians should at a minimum take these feelings seriously, not dismiss them. They may want to enlist the assistance of a gender identity clinic to address the social environment and guide the child in exploring activities with the self-identified gender, says Kelly McBride Folkers, research associate in the Division of Medical Ethics at New York University School of Medicine.
At one end of the spectrum, some parents and guardians are overzealous in supporting their child's gender-identity pursuits while the youngster is still in an early phase of decision-making. On the flipside, other parents and guardians are not at all supportive, leaving the child at risk for long-term psychological effects, says Folkers, who is also associate director of the High School Bioethics Project at NYU, an educational program that aids teachers and students in examining ethical and conceptual concepts across various areas, one of which is gender.
"It's important to help children navigate through this process early, so that they have all of the social and familial support they need if and when they choose to seek medical options for gender affirmation later," she says.
There are various reasons why children and adolescents want to explore the opposite gender when they reach puberty. "It's a small percentage who will persist and insist and be consistent with that opposite gender identity," says Nicole Mihalopoulos, adolescent medicine physician and associate professor of pediatrics at the University of Utah School of Medicine in Salt Lake City.
Turning to a social work support system can help bring clarity for teens, parents, and guardians.
For those youth, it's appropriate to start the conversation about a medication to block puberty, but without actually promoting a hormonal transition to the opposite gender, in order for the child to further explore living as the opposite gender. "Children need to start at puberty because we need to know that their bodies are physiologically normal," Mihalopoulos says.
A lack of breast development in girls or a lack of testicular development in boys could point to an abnormality in the hypothalamus, pituitary gland, or ovaries/testicles. "That needs to be identified and corrected first," she explains, "before I would say, 'Let's start on the medical transition path of the alternate gender.' "
For parents and guardians, says Theo Zachariah's aunt Miriam, it's very tempting to misinterpret a child's struggling attempts to articulate being trans as an adolescent identity crisis. That's when turning to a social work support system can bring clarity. A youth mental health agency with experience in trans issues made a positive impact on Theo's family through one-on-one counseling and in groups for teens and parents.
"The dialogue they were able to engage in with my nephew, his mom and us," she says, was very instrumental "in helping us all figure out what to do and how to navigate the change."
Can Cultured Meat Save the Planet?
In September, California governor Jerry Brown signed a bill mandating that by 2045, all of California's electricity will come from clean power sources. Technological breakthroughs in producing electricity from sun and wind, as well as lowering the cost of battery storage, have played a major role in persuading Californian legislators that this goal is realistic.
Even if the world were to move to an entirely clean power supply, one major source of greenhouse gas emissions would continue to grow: meat.
James Robo, the CEO of the Fortune 200 company NextEra Energy, has predicted that by the early 2020s, electricity from solar farms and giant wind turbines will be cheaper than the operating costs of coal-fired power plants, even when the cost of storage is included.
Can we therefore all breathe a sigh of relief, because technology will save us from catastrophic climate change? Not yet. Even if the world were to move to an entirely clean power supply, and use that clean power to charge up an all-electric fleet of cars, buses and trucks, one major source of greenhouse gas emissions would continue to grow: meat.
The livestock industry now accounts for about 15 percent of global greenhouse gas emissions, roughly the same as the emissions from the tailpipes of all the world's vehicles. But whereas vehicle emissions can be expected to decline as hybrids and electric vehicles proliferate, global meat consumption is forecast to be 76 percent greater in 2050 than it has been in recent years. Most of that growth will come from Asia, especially China, where increasing prosperity has led to an increasing demand for meat.
Changing Climate, Changing Diets, a report from the London-based Royal Institute of International Affairs, indicates the threat posed by meat production. At the UN climate change conference held in Cancun in 2010, the participating countries agreed that to allow global temperatures to rise more than 2°C above pre-industrial levels would be to run an unacceptable risk of catastrophe. Beyond that limit, feedback loops will take effect, causing still more warming. For example, the thawing Siberian permafrost will release large quantities of methane, causing yet more warming and releasing yet more methane. Methane is a greenhouse gas that, ton for ton, warms the planet 30 times as much as carbon dioxide.
The quantity of greenhouse gases we can put into the atmosphere between now and mid-century without heating up the planet beyond 2°C – known as the "carbon budget" -- is shrinking steadily. The growing demand for meat means, however, that emissions from the livestock industry will continue to rise, and will absorb an increasing share of this remaining carbon budget. This will, according to Changing Climate, Changing Diets, make it "extremely difficult" to limit the temperature rise to 2°C.
One reason why eating meat produces more greenhouse gases than getting the same food value from plants is that we use fossil fuels to grow grains and soybeans and feed them to animals. The animals use most of the energy in the plant food for themselves, moving, breathing, and keeping their bodies warm. That leaves only a small fraction for us to eat, and so we have to grow several times the quantity of grains and soybeans that we would need if we ate plant foods ourselves. The other important factor is the methane produced by ruminants – mainly cattle and sheep – as part of their digestive process. Surprisingly, that makes grass-fed beef even worse for our climate than beef from animals fattened in a feedlot. Cattle fed on grass put on weight more slowly than cattle fed on corn and soybeans, and therefore do burp and fart more methane, per kilogram of flesh they produce.
Richard Branson has suggested that in 30 years, we will look back on the present era and be shocked that we killed animals en masse for food.
If technology can give us clean power, can it also give us clean meat? That term is already in use, by advocates of growing meat at the cellular level. They use it, not to make the parallel with clean energy, but to emphasize that meat from live animals is dirty, because live animals shit. Bacteria from the animals' guts and shit often contaminates the meat. With meat cultured from cells grown in a bioreactor, there is no live animal, no shit, and no bacteria from a digestive system to get mixed into the meat. There is also no methane. Nor is there a living animal to keep warm, move around, or grow body parts that we do not eat. Hence producing meat in this way would be much more efficient, and much cleaner, in the environmental sense, than producing meat from animals.
There are now many startups working on bringing clean meat to market. Plant-based products that have the texture and taste of meat, like the "Impossible Burger" and the "Beyond Burger" are already available in restaurants and supermarkets. Clean hamburger meat, fish, dairy, and other animal products are all being produced without raising and slaughtering a living animal. The price is not yet competitive with animal products, but it is coming down rapidly. Just this week, leading officials from the Food and Drug Administration and the U.S. Department of Agriculture have been meeting to discuss how to regulate the expected production and sale of meat produced by this method.
When Kodak, which once dominated the sale and processing of photographic film, decided to treat digital photography as a threat rather than an opportunity, it signed its own death warrant. Tyson Foods and Cargill, two of the world's biggest meat producers, are not making the same mistake. They are investing in companies seeking to produce meat without raising animals. Justin Whitmore, Tyson's executive vice-president, said, "We don't want to be disrupted. We want to be part of the disruption."
That's a brave stance for a company that has made its fortune from raising and killing tens of billions of animals, but it is also an acknowledgement that when new technologies create products that people want, they cannot be resisted. Richard Branson, who has invested in the biotech company Memphis Meats, has suggested that in 30 years, we will look back on the present era and be shocked that we killed animals en masse for food. If that happens, technology will have made possible the greatest ethical step forward in the history of our species, saving the planet and eliminating the vast quantity of suffering that industrial farming is now inflicting on animals.