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.
Forcing Vaccination on Every Child Undermines Civil Liberties
[Editor's Note: This opinion essay is in response to our current Big Question, which we posed to experts with different viewpoints: "Where should society draw the line between requiring vaccinations for children and allowing parental freedom of choice?"]
Our children are the future. The survival of humanity is advanced by the biological imperative that mothers and fathers want and need to protect their children and other children from being harmed for any reason.
Science is not perfect, doctors are not infallible, and medical interventions come with risks.
In the 21st century, consensus science considers vaccination to be one of the greatest inventions in the history of medicine and the greatest achievement of public health programs. The national vaccination rate for U.S. kindergarten children is 94 percent and most children today receive 69 doses of 16 federally recommended vaccines. However, public health is not simply measured by high vaccination rates and absence of infectious disease, which is evidenced by the chronic inflammatory disease and disability epidemic threatening to bankrupt the U.S. health care system.
Science is not perfect, doctors are not infallible, and medical interventions come with risks, which is why parents have the power to exercise informed consent to medical risk taking on behalf of their minor children.
As a young mother, I learned that vaccine risks are 100 percent for some children because, while we are all born equal under the law, we are not born all the same. Each one of us enters this world with different genes, a unique microbiome and epigenetic influences that affect how we respond to the environments in which we live. We do not all respond the same way to infectious diseases or to pharmaceutical products like vaccines.
Few parents were aware of vaccine side effects in 1980, when my bright, healthy two-and-a-half year-old son, Chris, suffered a convulsion, collapse, and state of unconsciousness (encephalopathy) within hours of his fourth DPT shot, and then regressed physically, mentally and emotionally and became a totally different child. Chris was eventually diagnosed with multiple learning disabilities and confined to a special education classroom throughout his public school education, but he and I both know his vaccine reaction could have been much worse. Today, Chris is an independent adult but many survivors of brain injury are not.
Barbara Loe Fisher and her son, Chris, in December 1981 after his fourth DPT shot.
(Courtesy Fisher)
The public conversation about several hundred cases of measles reported in the U.S. this year is focused on whether every parent has a social obligation to vaccinate every child to maintain "community immunity," but vaccine failures are rarely discussed. Emerging science reveals that there are differences in naturally and vaccine acquired immunity, and both vaccinated and unvaccinated children and adults transmit infections, sometimes with few or no symptoms.
Nearly 40 percent of cases reported in the 2015 U.S. measles outbreak occurred in recently vaccinated individuals who developed vaccine reactions that appeared indistinguishable from measles. Outbreaks of pertussis (whooping cough) in highly vaccinated child populations have been traced to waning immunity and evolution of the B. pertussis microbe to evade the vaccines. Influenza vaccine effectiveness was less than 50 percent in 11 of the past 15 flu seasons.
Vaccine policymakers recognize that children with severe combined immune deficiency or those undergoing chemotherapy or organ transplants are at increased risk for complications of infectious diseases and vaccines. However, there is no recognition of the risks to healthy infants and children with unidentified susceptibility to vaccine reactions, including children whose health suddenly deteriorates without explanation after vaccination. Medical care is being denied to children and adults in the U.S. if even one government recommended vaccination is declined, regardless of health or vaccine reaction history.
When parents question the risks and failures of a commercial pharmaceutical product being mandated for every child, the answer is not more force but better science and respect for the informed consent ethic.
The social contract we have with each other when we live in communities, whether we belong to the majority or a minority, is to care about and protect every individual living in the community. One-size-fits-all vaccine policies and laws, which fail to respect biodiversity and force everyone to be treated the same, place an unequal risk burden on a minority of unidentified individuals unable to survive vaccination without being harmed.
A law that requires certain minorities to bear a greater risk of injury or sacrifice their lives in service to the majority is not just or moral.
Between 1991 and 2013, the Institute of Medicine (IOM) published reports documenting that vaccines can cause brain inflammation and other serious reactions, injuries and death. A 2012 IOM report acknowledged that there are genetic, biological, and environmental risk factors that make some individuals more susceptible to adverse responses to vaccines but often doctors cannot identify who they are because of gaps in vaccine science. Congress acknowledged this fact a quarter century earlier in the 1986 National Childhood Vaccine Injury Act, which created a federal vaccine injury compensation program alternative to a lawsuit that has awarded more than $4 billion to vaccine-injured children and adults.
We give up the human right to autonomy and informed consent at our peril, no matter where or in what century we live.
Vaccine manufacturers and administrators have liability protection, yet today almost no health condition qualifies for a medical vaccine exemption under government guidelines. Now, there is a global call by consensus science advocates for elimination of all personal belief vaccine exemptions and censorship of books and public conversations that criticize vaccine safety or government vaccine policy. Some are calling for quarantine of all who refuse vaccinations and criminal prosecution, fines and imprisonment of parents with unvaccinated children, as well as punishment of doctors who depart from government policy.
There is no civil liberty more fundamentally a natural, inalienable right than exercising freedom of thought and conscience when deciding when and for what reason we are willing to risk our life or our child's life. That is why voluntary, informed consent to medical risk-taking has been defined as a human right governing the ethical practice of modern medicine.
In his first Presidential inaugural address, Thomas Jefferson warned:
"All, too, will bear in mind this sacred principle, that though the will of the majority is in all cases to prevail, that will to be rightful must be reasonable; that the minority posses their equal rights, which equal law must protect, and to violate would be oppression."
The seminal 1905 U.S. Supreme Court decision, Jacobson v. Massachusetts, affirmed the constitutional authority of states to enact mandatory smallpox vaccination laws. However, the justices made it clear that implementation of a vaccination law should not become "cruel and inhuman to the last degree." They warned, "All laws, this court has said, should receive a sensible construction. General terms should be so limited in their application as not to lead to injustice, oppression, or an absurd consequence. It will always, therefore, be presumed that the legislature intended exceptions to its language, which would avoid results of this character."
Mothers and fathers, who know and love their children better than anyone else, depend upon sound science and compassionate public health policies to help them protect their own and other children from harm. If individuals susceptible to vaccine injury cannot be reliably identified, the accuracy of vaccine benefit and risk calculations must be reexamined. Yet, consensus science and medicine around vaccination discourages research into the biological mechanisms of vaccine injury and death and identification of individual risk factors to better inform public health policy.
A critic of consensus science, physician and author Michael Crichton said, "Let's be clear: the work of science has nothing whatever to do with consensus. Consensus is the business of politics. Period."
Condoning elimination of civil liberties, including freedom of speech and the right to dissent guaranteed under the First Amendment of the U.S. Constitution, to enforce vaccination creates a slippery slope. Coercion, punishment and censorship will destroy, not instill, public trust in the integrity of medical practice and public health laws.
There are more than a dozen new vaccines being fast tracked to market by industry and governments. Who in society should be given the power to force all children to use every one of them without parental consent regardless of how small or great the risk?
We give up the human right to autonomy and informed consent at our peril, no matter where or in what century we live. Just and compassionate public health laws that protect parental and human rights will include flexible medical, religious and conscientious belief vaccine exemptions to affirm the informed consent ethic and prevent discrimination against vulnerable minorities.
[Editor's Note: Read the opposite viewpoint here.]
Not Vaccinating Your Kids Endangers Public Health
[Editor's Note: This opinion essay is in response to our current Big Question, which we posed to experts with different viewpoints: "Where should society draw the line between requiring vaccinations for children and allowing parental freedom of choice?"]
Society has a right and at times an obligation to require children to be vaccinated. Vaccines are one of the most effective medical and public health interventions. They save lives and prevent suffering. The vast majority of parents in the United States fully vaccinate their children according to the recommended immunization schedule. These parents are making decisions so that the interests of their children and the interest of society are the same. There are no ethical tensions.
"Measles is only a plane ride away from American children."
A strong scientific basis supports the recommended immunization schedule. The benefits of recommended vaccines are much bigger than the risks. However, a very small proportion of parents are ideologically opposed to vaccines. A slightly larger minority of parents do not believe that all of the recommended vaccines are in their child's best interests.
Forgoing vaccinations creates risk to the child of contracting diseases. It also creates risk to communities and vulnerable groups of people who cannot be vaccinated because of their age or health status.
For example, many vaccines are not able to be given to newborns, such as the measles vaccine which is recommended at 12-15 months of age, leaving young children vulnerable. Many diseases are particularly dangerous for young children. There are also some children who can't be vaccinated, such as pediatric cancer patients who are undergoing chemotherapy or radiation treatment. These children are at increased risk of serous complication or death.
Then there are people who are vaccinated but remain susceptible to disease because no vaccine is 100% effective. In the case of measles, two doses of vaccines protect 97% of people, leaving 3% still susceptible even after being fully vaccinated. All of these groups of people – too young, not eligible, and vaccinated but still susceptible – are dependent on almost everyone else to get vaccinated in order for them to be protected.
Sadly, even though measles has been largely controlled because most people get the very safe and very effective vaccine, we are now seeing dangerous new outbreaks because some parents are refusing vaccines for their children, especially in Europe. Children have died. Measles is only a plane ride away from American children.
There have been repeated measles outbreaks in the United States – such as the Disneyland outbreak and six outbreaks already this year - because of communities where too many parents refuse the vaccine and measles is brought over, often from Europe.
The public health benefits cannot be emphasized enough: Vaccines are not just about protecting your child. Vaccines protect other children and the entire community. Vaccine-preventable diseases (with the exception of tetanus) are spread from person to person. The decision of a parent to not vaccinate their child can endanger other children and vulnerable people.
As a vaccine safety researcher for 20 years, I believe that the community benefit of vaccination can provide justification to limit parental autonomy.
Given these tensions between parental autonomy and the protective value of vaccines, the fundamental question remains: Should society require all children to submit to vaccinations? As a vaccine safety researcher for 20 years, I believe that the community benefit of vaccination can provide justification to limit parental autonomy.
In the United States, we see this balancing act though state requirements for vaccinations to enter school and the varying availability of non-medical exemptions to these laws. Mandatory vaccination in the United States are all state laws. All states require children entering school to receive vaccines and permit medical exemptions. There are a lot of differences between states regarding which vaccines are required, target populations (daycare, school entry, middle school, college), and existence and types of non-medical (religious or philosophical) exemptions that are permitted.
Amid recent measles outbreaks, for instance, California eliminated all non-medical exemptions, making it one of three states that only permit medical exemptions. The existence and enforcement of these school laws reflect broad public support for vaccines to protect the community from disease outbreaks.
I worry about how many kids must suffer, and even die, from diseases like measles until enough is enough. Such tragedies have no place in the modern era. All parents want to do right by their children. All parents deserve autonomy when it comes to decision-making. But when their choices confer serious risks to others, the buck should stop. Our nation would be better off—both medically and ethically—if we did not turn our backs on our most vulnerable individuals.
[Editor's Note: Read the opposite viewpoint here.]