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.
Taboo topics occupy a difficult place in the history of medicine. Society has long been reticent about confronting stigmatized conditions, forcing many patients to suffer in silence and isolation, often with poorer care.
"Classically, doctors don't purposely kill people. That is really the core of the resistance."
AIDS activists recognized this in the 1980s when they coined the phrase Silence = Death to generate public debate and action over a growing epidemic that until then had existed largely in the shadows. The slogan and the activists behind it were remarkably successful at changing the public discourse.
It is not a lone example. Post-World War II medicine is better because it came to deal more forthrightly with a broad range of medical conditions from conception/abortion, to cancer, to sexually transmitted infections. The most recent issue to face such scrutiny is physician-assisted dying (PAD).
"Classically, doctors don't purposely kill people…that is really the core of the resistance" to PAD from the provider perspective, says Neil Wenger, an internist and ethicist at the University of California Los Angeles who focuses on end-of-life issues.
But from the patient perspective, the option of PAD "provides important psychological benefits ... because it gives the terminally ill autonomy, control, and choice," argued the American Public Health Association in support of Oregon's death with dignity legislation.
Jack Kervorkian, "Dr. Death," was one of the first to broach the subject when few in polite society were willing to do so. The modern era truly began twenty years ago when the citizens of Oregon embraced the option of death with dignity in a public referendum, over the objections of their political leaders.
Expansion of the legal option in North America was incremental until 2016 when the Supreme Court in Canada and legislators in California decided that control over one's body extended to death, at least under certain explicit conditions.
An estimated 18 percent of Americans now live in jurisdictions that provide the legal option of assisted death, but exercising that right can be difficult. Only a fraction of one percent of deaths are by PAD, even in Oregon.
Stakeholder Roles
Few organizations of healthcare professionals in the U.S. support PAD; some actively oppose it, others have switched to a position of neutrality while they study the issue.
One doctor wanted to organize a discussion of physician-assisted dying at his hospital, but administrators forbade it.
But once a jurisdiction makes the political/legal decision that patients have a right to physician-assisted death, what are the roles and responsibilities of medical stakeholders? Can they simply opt out in a vow of silence? Or do organizations bear some sort of obligation to ensure access to that right, no matter their own position, particularly when they are both regulated by and receive operating funds from public sources?
The law in California and other U.S. jurisdictions reflects ambivalence about PAD by treating it differently from other medical practices, says David Magnus, an ethicist at Stanford University School of Medicine. It is allowed but "it's intentionally a very, very burdensome process."
Medical decisions, including withdrawing life support or a do not resuscitate [DNR] order, are between a physician and the patient or guardian. But PAD requires outside consultation and documentation that is quite rigorous, even burdensome, Magnus explains. He recalls one phone consult with a physician who had to re-have a conversation with a patient at home in order to meet the regulatory requirements for a request for assistance in dying. "So it is not surprising that it is utilized so infrequently."
The federal government has erected its own series of barriers. Roused by the experience in Oregon, opponents tried to ban PAD at the national level. They failed but did the next best thing; they prohibited use of federal funds to pay for or even discuss PAD. That includes Medicare, Medicaid, and the large health delivery systems run by the Pentagon and Veterans Affairs. The restrictions parallel those on federal funding for access to abortion and medical marijuana.
Even physicians who support and perform PAD are reluctant to talk about it. They are unwilling to initiate the discussion with patients, says Mara Buchbinder, a bioethicist at the University of North Carolina at Chapel Hill who has interviewed physicians, patients, and families about their experience with assisted dying in Vermont.
"There is a stigma for health care workers to talk about this; they feel that they are not supported," says Buchbinder. She relates how one doctor wanted to organize a discussion of PAD at his hospital, but administrators forbade it. And when the drug used to carry out the procedure became prohibitively expensive, other physicians were not aware of alternatives.
"This just points to large inadequacies in medical preparation around end-of-life conversations," says Buchbinder, a view endorsed by many experts interviewed for this article.
These inadequacies are reinforced when groups like the Coalition to Transform Advanced Care (C-TAC), a 140-member organizational alliance that champions improved end-of-life care, dodges the issue. A spokesman said simply, PAD "is not within the scope of our work."
The American Medical Association has had a policy in place opposing PAD since 1993. Two years ago, its House of Delegates voted to reevaluate their position in light of evolving circumstances. Earlier this year the Council of Ethical and Judicial Affairs recommended continued opposition, but in June, the House of Delegates rejected that recommendation (56 to 44 percent) and directed the Council to keep studying the issue.
Only those with the economic and social capital and network of advocates will succeed in exercising this option.
Kaiser Permanente has provided assisted dying to its members in multiple states beginning with Oregon and has done "a wonderful job" according to supporters of PAD. But it has declined to discuss those activities publicly despite a strenuous effort to get them to do so.
Rather than drawing upon formal structures for leadership and guidance, doctors who are interested in learning more about PAD are turning to the ad hoc wisdom of providers from Oregon and Washington who have prior experience. Magnus compares it with what usually happens when a new intervention or technology comes down the pike: "People who have done it, have mastered it, pass that knowledge on to other people so they know how to do it."
Buchbinder says it becomes an issue of social justice when providers are not adequately trained, and when patients are not ordinarily offered the option of a medical service in jurisdictions where it is their right.
Legalization of PAD "does not guarantee practical access, and well-intentioned policies designed to protect vulnerable groups may at times reinforce or exacerbate health care inequalities," she says. Only those with the economic and social capital and network of advocates will succeed in exercising this option.
O Canada
Canada provides a case study of how one might address PAD. They largely settled on the term medical aid in dying – often shortened to MAID – as the more neutral phrase for their law and civil discourse.
The Canadian Medical Association (CMA) decided early on to thread the needle; to not take a position on the core issue of morality but to proactively foster public discussion of those issues as the legal challenge to the ban on assisted dying headed to that country's Supreme Court.
"We just felt that it was too important for the profession to sit on the sidelines and not be part of the discussion," says Jeff Blackmer, CMA's vice president for medical professionalism.
It began by shifting the focus of discussion from a yes/no on the morality of MAID to the questions of, "If the court rules that the current laws are unconstitutional, and they allow assisted dying, how should the profession react and how should we respond? And how does the public think that the profession should respond?"
"I had to wear a flack jacket, a bulletproof vest, and there were plainclothes police officers with guns in the audience because it is really really very controversial."
The CMA teamed up with Maclean's magazine to host a series of five town hall meetings throughout the country. Assisted dying was discussed in a context of palliative care, advanced care planning, and other end-of-life issues.
There was fear that MAID might raise passions and even violence that has been seen in recent controversies over abortion. "I had to wear a flack jacket, a bulletproof vest, and there were plainclothes police officers with guns in the audience because it is really really very controversial," Blackmer recalls. Thankfully there were no major incidents.
The CMA also passed a resolution at its annual meeting supporting the right of its members to opt out of participating in MAID, within the confines of whatever law might emerge.
Once legislation and regulations began taking shape, the CMA created training materials on the ethical, legal, and practical consideration that doctors and patients might face. It ordinarily does not get involved with clinical education and training.
Stefanie Green is president of Canadian Association of MAID Assessors & Providers, a professional medical association that supports those working in the area of assisted dying, educates the public and health care community, and provides leadership on setting medical standards. Green acknowledges the internal pressures the CMA faced, and says, "I do understand their stance is as positive as it gets for medical associations."
Back in the USofA
Prohibitionism – the just say no approach – does not work when a substantial number of people want something, as demonstrated with alcohol, marijuana, opioids for pain relief, and reproductive control. Reason suggests a harm reduction strategy is the more viable approach.
"Right now we're stuck in the worst of all worlds because we've made [PAD] sort of part of medicine, but sort of illicit and sort of shameful. And we sort of allow it, but we sort of don't, we make it hard," says Stanford's Magnus. "And that's a no man's land where we are stuck."
Imagine this scenario: A couple is involved in a heated custody dispute over their only child. As part of the effort to make the case of being a better guardian, one parent goes on a "genetic fishing expedition": this parent obtains a DNA sample from the other parent with the hope that such data will identify some genetic predisposition to a psychiatric condition (e.g., schizophrenia) and tilt the judge's custody decision in his or her favor.
As knowledge of psychiatric genetics is growing, it is likely to be introduced in civil cases, such as child custody disputes and education-related cases, raising a tangle of ethical and legal questions.
This is an example of how "behavioral genetic evidence" -- an umbrella term for information gathered from family history and genetic testing about pathological behaviors, including psychiatric conditions—may in the future be brought by litigants in court proceedings. Such evidence has been discussed primarily when criminal defendants sought to introduce it to make the claim that they are not responsible for their behavior or to justify their request for reduced sentencing and more lenient punishment.
However, civil cases are an emerging frontier for behavioral genetic evidence. It has already been introduced in tort litigation, such as personal injury claims, and as knowledge of psychiatric genetics is growing, it is further likely to be introduced in other civil cases, such as child custody disputes and education-related cases. But the introduction of such evidence raises a tangle of ethical and legal questions that civil courts will need to address. For example: how should such data be obtained? Who should get to present it and under what circumstances? And does the use of such evidence fit with the purposes of administering justice?
How Did We Get Here?
That behavioral genetic evidence is entering courts is unsurprising. Scientific evidence is a common feature of judicial proceedings, and genetic information may reveal relevant findings. For example, genetic evidence may elucidate whether a child's medical condition is due to genetic causes or medical malpractice, and it has been routinely used to identify alleged offenders or putative fathers. But behavioral genetic evidence is different from such other genetic data – it is shades of gray, instead of black and white.
Although efforts to understand the nature and origins of human behavior are ongoing, existing and likely future knowledge about behavioral genetics is limited. Behavioral disorders are highly complex and diverse. They commonly involve not one but multiple genes, each with a relatively small effect. They are impacted by many, yet unknown, interactions between genes, familial, and environmental factors such as poverty and childhood adversity.
And a specific gene variant may be associated with more than one behavioral disorder and be manifested with significantly different symptoms. Thus, biomarkers about "predispositions" for behavioral disorders cannot generally provide a diagnosis or an accurate estimate of whether, when, and at what severity a behavioral disorder will occur. And, unlike genetic testing that can confirm litigants' identity with 99.99% probability, behavioral genetic evidence is far more speculative.
Genetic theft raises questions about whose behavioral data are being obtained, by whom, and with what authority.
Whether judges, jurors, and other experts understand the nuances of behavioral genetics is unclear. Many people over-estimate the deterministic nature of genetics, and under-estimate the role of environments, especially with regards to mental health status. The U.S. individualistic culture of self-reliance and independence may further tilt the judicial scales because litigants in civil courts may be unjustly blamed for their "bad genes" while structural and societal determinants that lead to poor behavioral outcomes are ignored.
These concerns were recently captured in the Netflix series "13 Reasons Why," depicting a negligence lawsuit against a school brought by parents of a high-school student there (Hannah) who committed suicide. The legal tides shifted from the school's negligence in tolerating a culture of bullying to parental responsibility once cross-examination of Hannah's mother revealed a family history of anxiety, and the possibility that Hannah had a predisposition for mental illness, which (arguably) required therapy even in the absence of clear symptoms.
Where Is This Going?
The concerns are exacerbated given the ways in which behavioral genetic evidence may come to court in the future. One way is through "genetic theft," where genetic evidence is obtained from deserted property, such as soft-drink cans. This method is often used for identification purposes such as criminal and paternity proceedings, and it will likely expand to behavioral genetic data once available through "home kits" that are offered by direct-to-consumer companies.
Genetic theft raises questions about whose behavioral data are being obtained, by whom, and with what authority. In the scenario of child-custody dispute, for example, the sequencing of the other parent's DNA will necessarily intrude on the privacy of that parent, even as the scientific value of such information is limited. A parent on a "genetic fishing expedition" can also secretly sequence their child for psychiatric genetic predispositions, arguably, in order to take preventative measures to reduce the child's risk for developing a behavioral disorder. But should a parent be allowed to sequence the child without the other parent's consent, or regardless of whether the results will provide medical benefits to the child?
Similarly, although schools are required, and may be held accountable for failing to identify children with behavioral disabilities and to evaluate their educational needs, some parents may decline their child's evaluation by mental health professionals. Should schools secretly obtain a sample and sequence children for behavioral disorders, regardless of parental consent? My study of parents found that the overwhelming majority opposed imposed genetic testing by school authorities. But should parental preference or the child's best interests be the determinative factor? Alternatively, could schools use secretly obtained genetic data as a defense that they are fulfilling the child-find requirement under the law?
The stigma associated with behavioral disorders may intimidate some people enough that they back down from just claims.
In general, samples obtained through genetic theft may not meet the legal requirements for admissible evidence, and as these examples suggest, they also involve privacy infringement that may be unjustified in civil litigation. But their introduction in courts may influence judicial proceedings. It is hard to disregard such evidence even if decision-makers are told to ignore it.
The costs associated with genetic testing may further intensify power differences among litigants. Because not everyone can pay for DNA sequencing, there is a risk that those with more resources will be "better off" in court proceedings. Simultaneously, the stigma associated with behavioral disorders may intimidate some people enough that they back down from just claims. For example, a good parent may give up a custody claim to avoid disclosure of his or her genetic predispositions for psychiatric conditions. Regulating this area of law is necessary to prevent misuses of scientific technologies and to ensure that powerful actors do not have an unfair advantage over weaker litigants.
Behavioral genetic evidence may also enter the courts through subpoena of data obtained in clinical, research or other commercial genomic settings such as ancestry testing (similar to the genealogy database recently used to identify the Golden State Killer). Although court orders to testify or present evidence are common, their use for obtaining behavioral genetic evidence raises concerns.
One worry is that it may be over-intrusive. Because behavioral genetics are heritable, such data may reveal information not only about the individual litigant but also about other family members who may subsequently be stigmatized as well. And, even if we assume that many people may be willing for their data in genomic databases to be used to identify relatives who committed crimes (e.g., a rapist or a murderer), we can't assume the same for civil litigation, where the public interest in disclosure is far weaker.
Another worry is that it may deter people from participating in activities that society has an interest in advancing, including medical treatment involving genetic testing and genomic research. To address this concern, existing policy provides expanded privacy protections for NIH-funded genomic research by automatically issuing a Certificate of Confidentiality that prohibits disclosure of identifiable information in any Federal, State, or local civil, criminal, and other legal proceedings.
But this policy has limitations. It applies only to specific research settings and does not cover non-NIH funded research or clinical testing. The Certificate's protections can also be waived under certain circumstances. People who volunteer to participate in non-NIH-funded genomic research for the public good may thus find themselves worse-off if embroiled in legal proceedings.
Consider the following: if a parent in a child custody dispute had participated in a genetic study on schizophrenia years earlier, should the genetic results be subpoenaed by the court – and weaponized by the other parent? Public policy should aim to reduce the risks for such individuals. The end of obtaining behavioral genetic evidence cannot, and should not, always justify the means.