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.
Shoot for the Moon: Its Surface Contains a Pot of Gold
Here's a riddle: What do the Moon, nuclear weapons, clean energy of the future, terrorism, and lung disease all have in common?
One goal of India's upcoming space probe is to locate deposits of helium-3 that are worth trillions of dollars.
The answer is helium-3, a gas that's extremely rare on Earth but 100 million times more abundant on the Moon. This past October, the Lockheed Martin corporation announced a concept for a lunar landing craft that may return humans to the Moon in the coming decade, and yesterday China successfully landed the Change-4 probe on the far side of the Moon. Landing inside the Moon's deepest crater, the Chinese achieved a first in space exploration history.
Meanwhile, later this month, India's Chandrayaan-2 space probe will also land on the lunar surface. One of its goals is to locate deposits of helium-3 that are worth trillions of dollars, because it could be a fuel for nuclear fusion energy to generate electricity or propel a rocket.
The standard way that nuclear engineers are trying to achieve sustainable fusion uses fuels that are more plentiful on Earth: deuterium and tritium. But MIT researchers have found that adding small amounts of helium-3 to the mix could make it much more efficient, and thus a viable energy source much sooner that once thought.
Even if fusion is proven practical tomorrow, any kind of nuclear energy involves long waits for power plant construction measured in decades. However, mining helium-3 could be useful now, because of its non-energy applications. A major one is its ability to detect neutrons coming from plutonium that could be used in terrorist attacks. Here's how it works: a small amount of helium-3 is contained within a forensic instrument. When a neutron hits an atom of helium-3, the reaction produces tritium, a proton, and an electrical charge, alerting investigators to the possibility that plutonium is nearby.
Ironically, as global concern about a potential for hidden nuclear material increased in the early 2000s, so did the supply of helium-3 on Earth. That's because helium-3 comes from the decay of tritium, used in thermonuclear warheads (H-bombs). Thousands of such weapons have been dismantled from U.S. and Russian arsenals, making helium-3 available for plutonium detection, research, and other applications--including in the world of healthcare.
Helium-3 can help doctors diagnose lung diseases, since it enables imaging of the lungs in real time.
Helium-3 dramatically improves the ability of doctors to image the lungs in a range of diseases including asthma, chronic obstructive pulmonary disease and emphysema, cystic fibrosis, and bronchopulmonary dysplasia, which happens particularly in premature infants. Specifically, helium-3 is useful in magnetic resonance imaging (MRI), a procedure that creates images from within the body for diagnostic purposes.
But while a standard MRI allows doctors to visualize parts of the body like the heart or brain, it's useless for seeing the lungs. Because lungs are filled with air, which is much less dense than water or fat, effectively no signals are produced that would enable imaging.
To compensate for this problem, a patient can inhale gas that is hyperpolarized –meaning enhanced with special procedures so that the magnetic resonance signals from the lungs are finally readable. This gas is safe to breathe when mixed with enough oxygen to support life. Helium-3 is one such gas that can be hyperpolarized; since it produces such a strong signal, the MRI can literally see the air inside the lungs and in all of the airways, revealing intricate details of the bronchopulmonary tree. And it can do this in real time
The capability to show anatomic details of the lungs and airways, and the ability to display functional imaging as a patient breathes, makes helium-3 MRI far better than the standard method of testing lung function. Called spirometry, this method tells physicians how the lungs function overall, but does not home in on particular areas that may be causing a problem. Plus, spirometry requires patients to follow instructions and hold their breath, so it is not great for testing young children with pulmonary disease.
In recent years, the cost of helium-3 on Earth has skyrocketed.
Over the past several years, researchers have been developing MRI for lung testing using other hyperpolarized gases. The main alternative to helium-3 is xenon-129. Over the years, researchers have learned to overcome certain disadvantages of the latter, such as its potential to put patients to sleep. Since helium-3 provides the strongest signal, though, it is still the best gas for MRI studies in many lung conditions.
But the supply of helium-3 on Earth has been decreasing in recent years, due to the declining rate of dismantling of warheads, just as the Department of Homeland Security has required more and more of the gas for neutron detection. As a result, the cost of the gas has skyrocketed. Less is available now for medical uses – unless, of course, we begin mining it on the moon.
The question is: Are the benefits worth the 239,000-mile trip?
Should Organ Donors Be Paid?
Deanna Santana had assumed that people on organ transplant lists received matches. She didn't know some died while waiting. But in May 2011, after her 17-year-old son, Scott, was killed in a car accident, she learned what a precious gift organ and tissue donation can be.
"I would estimate it cost our family about $4,000 for me to donate a kidney to a stranger."
His heart, lungs, kidneys, liver and pancreas saved five people. His corneas enabled two others to see. And his bones, connective tissues and veins helped 73 individuals.
The donation's impact had a profound effect on his mother as well. In September 2016, she agreed to donate a kidney in a paired exchange of four people making the same sacrifice for four compatible strangers.
She gave up two weeks' worth of paid vacation to recuperate and covered lodging costs for loved ones during her transplant. Eventually, she qualified for state disability for part of her leave, but the compensation was less than her salary as public education and relations manager at Sierra Donor Services, an organ procurement organization in West Sacramento, California.
"I would estimate it cost our family about $4,000 for me to donate a kidney to a stranger," says Santana, 51. Despite the monetary hardship, she "would do it again in a heartbeat."
While some contend it's exploitative to entice organ donors and their families with compensation, others maintain they should be rewarded for extending their generosity while risking complications and recovering from donation surgery. But many agree on one point: The focus should be less on paying donors and more on removing financial barriers that may discourage interested prospects from doing a good deed.
"There's significant potential risk associated with donating a kidney, some of which we're continuing to learn," says transplant surgeon Matthew Cooper, a board member of the National Kidney Foundation and co-chair of its Transplant Task Force.
Although most kidneys are removed laparoscopically, reducing hospitalization and recuperation time, complications can occur. The risks include wound and urinary tract infections, pneumonia, blood clots, injury to local nerves causing decreased sensation in the hip or thigh, acute blood loss requiring transfusion and even death, Cooper says.
"We think that donation is a cost-neutral opportunity. It, in fact, is not."
Meanwhile, from a financial standpoint, estimates have found it costs a kidney donor in the United States an average of $3,000 to navigate the entire transplant process, which may include time off from work, travel to and from the hospital, accommodations, food and child care expenses.
"We think that donation is a cost-neutral opportunity. It, in fact, is not," says Cooper, who is also Director of Kidney and Pancreas Transplantation at MedStar Georgetown Transplant Institute in Washington, D.C.
The National Organ Transplant Act of 1984 makes it illegal to sell human organs but did not prohibit payment for the donation of human plasma, sperm and egg cells.
Unlike plasma, sperm and eggs cells—which are "renewable resources"—a kidney is irreplaceable, says John J. Friedewald, a nephrologist who is medical director of kidney transplantation at Northwestern Memorial Hospital in Chicago.
Offering some sort of incentives could lessen the overall burden on donors while benefiting many more potential recipients. "We can eliminate the people waiting on the list and dying, at least for kidneys," Friedewald says.
On the other hand, incentives may influence an individual to the point that the donation is made purely for monetary gain. "It's a delicate balance," he explains, "because so much of the transplant system has been built on altruism."
That's where doing away with the "disincentives" comes into the equation. Compensating donors for the costs they endure would be a reasonable compromise, Friedewald says.
Depending on the state, living donors may deduct up to $10,000 from their adjusted gross income under the Organ Donation Tax Deduction Act for the year in which the transplantation occurs. "Human organ" applies to all or part of a liver, pancreas, kidney, intestine, lung or bone marrow. The subtracted modification may be claimed for only unreimbursed travel and lodging expenses and lost wages.
For some or many donors, the tax credit doesn't go far enough in offsetting their losses, but they often take it in stride, says Chaya Lipschutz, a Brooklyn, N.Y.-based matchmaker for donors and recipients, who launched the website KidneyMitzvah.com in 2009.
Seeking compensation for lost wages "is extremely rare" in her experience. "In all the years of doing this," she recalls, "I only had two people who donated a kidney who needed to get paid for lost wages." She finds it "pretty amazing that mostly all who contact don't ask."
Lipschutz, an Orthodox Jew, has walked in a donor's shoes. In September 2005, at age 48, she donated a kidney to a stranger after coming across an ad in a weekly Jewish newspaper. The ad stated: "Please help save a Jewish life—New Jersey mother of two in dire need of kidney—Whoever saves one life from Israel it is as if they saved an entire nation."
To make matches, Lipschutz posts in various online groups in the United States and Israel. Donors in Israel may receive "refunds" for loss of earnings, travel expenses, psychological treatment, recovery leave, and insurance. They also qualify for visits to national parks and nature reserves without entrance fees, Lipschutz says.
"There has been an attempt to figure out what would constitute fair compensation without the appearance that people are selling their organs or their loved ones' organs."
Kidneys can be procured from healthy living donors or patients who have undergone circulatory or brain death.
"The real dilemma arises with payment for living donation, which would favor poorer individuals to donate who would not necessarily do so," says Dr. Cheryl L. Kunis, a New York-based nephrologist whose practice consists primarily of kidney transplant recipients. "In addition, such payment for living donation has not demonstrated to improve a donor's socioeconomic status globally."
Living kidney donation has the highest success rate. But organs from young and previously healthy individuals who die in accidents or from overdoses, especially in the opioid epidemic, often work just as well as kidneys from cadaveric donors who succumb to trauma, Kunis says.
In these tragic circumstances, she notes that the decision to donate is often left to an individual's grieving family members when a living will isn't available. A payment toward funeral expenses, for instance, could tip their decision in favor of organ donation.
A similar scenario presents when a patient with a beating heart is on the verge of dying, and the family is unsure about consenting to organ donation, says Jonathan D. Moreno, a professor in the department of medical ethics and health policy at the University of Pennsylvania.
"There has been an attempt to figure out what would constitute fair compensation," he says, "without the appearance that people are selling their organs or their loved ones' organs."
The overarching concern remains the same: Compensating organ donors could lead to exploitation of socioeconomically disadvantaged groups. "What's likely to finally resolve" this bioethics debate, Moreno foresees, "is patient-compatible organs grown in pigs as the basic science of xenotransplants (between species) seems to be progressing."
Cooper, the transplant surgeon at Georgetown, believes more potential donors would come forward if financial barriers weren't an issue. Of the ones who end up giving a part of themselves, with or without reimbursement, "the overwhelming majority look back upon it as an extremely positive experience," he says. After all, "they're lifesavers. They should be celebrated."