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.
Should We Use Technologies to Enhance Morality?
Our moral ‘hardware’ evolved over 100,000 years ago while humans were still scratching the savannah. The perils we encountered back then were radically different from those that confront us now. To survive and flourish in the face of complex future challenges our archaic operating systems might need an upgrade – in non-traditional ways.
Morality refers to standards of right and wrong when it comes to our beliefs, behaviors, and intentions. Broadly, moral enhancement is the use of biomedical technology to improve moral functioning. This could include augmenting empathy, altruism, or moral reasoning, or curbing antisocial traits like outgroup bias and aggression.
The claims related to moral enhancement are grand and polarizing: it’s been both tendered as a solution to humanity’s existential crises and bluntly dismissed as an armchair hypothesis. So, does the concept have any purchase? The answer leans heavily on our definition and expectations.
One issue is that the debate is often carved up in dichotomies – is moral enhancement feasible or unfeasible? Permissible or impermissible? Fact or fiction? On it goes. While these gesture at imperatives, trading in absolutes blurs the realities at hand. A sensible approach must resist extremes and recognize that moral disrupters are already here.
We know that existing interventions, whether they occur unknowingly or on purpose, have the power to modify moral dispositions in ways both good and bad. For instance, neurotoxins can promote antisocial behavior. The ‘lead-crime hypothesis’ links childhood lead-exposure to impulsivity, antisocial aggression, and various other problems. Mercury has been associated with cognitive deficits, which might impair moral reasoning and judgement. It’s well documented that alcohol makes people more prone to violence.
So, what about positive drivers? Here’s where it gets more tangled.
Medicine has long treated psychiatric disorders with drugs like sedatives and antipsychotics. However, there’s short mention of morality in the Diagnostic and Statistical Manual of Mental Disorders (DSM) despite the moral merits of pharmacotherapy – these effects are implicit and indirect. Such cases are regarded as treatments rather than enhancements.
It would be dangerously myopic to assume that moral augmentation is somehow beyond reach.
Conventionally, an enhancement must go beyond what is ‘normal,’ species-typical, or medically necessary – this is known as the ‘treatment-enhancement distinction.’ But boundaries of health and disease are fluid, so whether we call a procedure ‘moral enhancement’ or ‘medical treatment’ is liable to change with shifts in social values, expert opinions, and clinical practices.
Human enhancements are already used for a range of purported benefits: caffeine, smart drugs, and other supplements to boost cognitive performance; cosmetic procedures for aesthetic reasons; and steroids and stimulants for physical advantage. More boldly, cyborgs like Moon Ribas and Neil Harbisson are pushing transpecies boundaries with new kinds of sensory perception. It would be dangerously myopic to assume that moral augmentation is somehow beyond reach.
How might it work?
One possibility for shaping moral temperaments is with neurostimulation devices. These use electrodes to deliver a low-intensity current that alters the electromagnetic activity of specific neural regions. For instance, transcranial Direct Current Stimulation (tDCS) can target parts of the brain involved in self-awareness, moral judgement, and emotional decision-making. It’s been shown to increase empathy and valued-based learning, and decrease aggression and risk-taking behavior. Many countries already use tDCS to treat pain and depression, but evidence for enhancement effects on healthy subjects is mixed.
Another suggestion is targeting neuromodulators like serotonin and dopamine. Serotonin is linked to prosocial attributes like trust, fairness, and cooperation, but low activity is thought to motivate desires for revenge and harming others. It’s not as simple as indiscriminately boosting brain chemicals though. While serotonin is amenable to SSRIs, precise levels are difficult to measure and track, and there’s no scientific consensus on the “optimum” amount or on whether such a value even exists. Fluctuations due to lifestyle factors such as diet, stress, and exercise add further complexity. Currently, more research is needed on the significance of neuromodulators and their network dynamics across the moral landscape.
There are a range of other prospects. The ‘love drugs’ oxytocin and MDMA mediate pair bonding, cooperation, and social attachment, although some studies suggest that people with high levels of oxytocin are more aggressive toward outsiders. Lithium is a mood stabilizer that has been shown to reduce aggression in prison populations; beta-blockers like propranolol and the supplement omega-3 have similar effects. Increasingly, brain-computer interfaces augur a world of brave possibilities. Such appeals are not without limitations, but they indicate some ways that external tools can positively nudge our moral sentiments.
Who needs morally enhancing?
A common worry is that enhancement technologies could be weaponized for social control by authoritarian regimes, or used like the oppressive eugenics of the early 20th century. Fortunately, the realities are far more mundane and such dystopian visions are fantastical. So, what are some actual possibilities?
Some researchers suggest that neurotechnologies could help to reactivate brain regions of those suffering from moral pathologies, including healthy people with psychopathic traits (like a lack of empathy). Another proposal is using such technology on young people with conduct problems to prevent serious disorders in adulthood.
Most of us aren’t always as ethical as we would like – given the option of ‘priming’ yourself to act in consistent accord with your higher values, would you take it?
A question is whether these kinds of interventions should be compulsory for dangerous criminals. On the other hand, a voluntary treatment for inmates wouldn’t be so different from existing incentive schemes. For instance, some U.S. jurisdictions already offer drug treatment programs in exchange for early release or instead of prison time. Then there’s the difficult question of how we should treat non-criminal but potentially harmful ‘successful’ psychopaths.
Others argue that if virtues have a genetic component, there is no technological reason why present practices of embryo screening for genetic diseases couldn’t also be used for selecting socially beneficial traits.
Perhaps the most immediate scenario is a kind of voluntary moral therapy, which would use biomedicine to facilitate ideal brain-states to augment traditional psychotherapy. Most of us aren’t always as ethical as we would like – given the option of ‘priming’ yourself to act in consistent accord with your higher values, would you take it? Approaches like neurofeedback and psychedelic-assisted therapy could prove helpful.
What are the challenges?
A general challenge is that of setting. Morality is context dependent; what’s good in one environment may be bad in another and vice versa, so we don’t want to throw out the baby with the bathwater. Of course, common sense tells us that some tendencies are more socially desirable than others: fairness, altruism, and openness are clearly preferred over aggression, dishonesty, and prejudice.
One argument is that remoulding ‘brute impulses’ via biology would not count as moral enhancement. This view claims that for an action to truly count as moral it must involve cognition – reasoning, deliberation, judgement – as a necessary part of moral behavior. Critics argue that we should be concerned more with ends rather than means, so ultimately it’s outcomes that matter most.
Another worry is that modifying one biological aspect will have adverse knock-on effects for other valuable traits. Certainly, we must be careful about the network impacts of any intervention. But all stimuli have distributed effects on the body, so it’s really a matter of weighing up the cost/benefit trade-offs as in any standard medical decision.
Is it ethical?
Our values form a big part of who we are – some bioethicists argue that altering morality would pose a threat to character and personal identity. Another claim is that moral enhancement would compromise autonomy by limiting a person’s range of choices and curbing their ‘freedom to fall.’ Any intervention must consider the potential impacts on selfhood and personal liberty, in addition to the wider social implications.
This includes the importance of social and genetic diversity, which is closely tied to considerations of fairness, equality, and opportunity. The history of psychiatry is rife with examples of systematic oppression, like ‘drapetomania’ – the spurious mental illness that was thought to cause African slaves’ desire to flee captivity. Advocates for using moral enhancement technologies to help kids with conduct problems should be mindful that they disproportionately come from low-income communities. We must ensure that any habilitative practice doesn’t perpetuate harmful prejudices by unfairly targeting marginalized people.
Human capacities are the result of environmental influences, and external conditions still coax our biology in unknown ways. Status quo bias for ‘letting nature take its course’ may actually be worse long term – failing to utilize technology for human development may do more harm than good.
Then, there are concerns that morally-enhanced persons would be vulnerable to predation by those who deliberately avoid moral therapies. This relates to what’s been dubbed the ‘bootstrapping problem’: would-be moral enhancement candidates are the types of individuals that benefit from not being morally enhanced. Imagine if every senator was asked to undergo an honesty-boosting procedure prior to entering public office – would they go willingly? Then again, perhaps a technological truth-serum wouldn’t be such a bad requisite for those in positions of stern social consequence.
Advocates argue that biomedical moral betterment would simply offer another means of pursuing the same goals as fixed social mechanisms like religion, education, and community, and non-invasive therapies like cognitive-behavior therapy and meditation. It’s even possible that technological efforts would be more effective. After all, human capacities are the result of environmental influences, and external conditions still coax our biology in unknown ways. Status quo bias for ‘letting nature take its course’ may actually be worse long term – failing to utilize technology for human development may do more harm than good. If we can safely improve ourselves in direct and deliberate ways then there’s no morally significant difference whether this happens via conventional methods or new technology.
Future prospects
Where speculation about human enhancement has led to hype and technophilia, many bioethicists urge restraint. We can be grounded in current science while anticipating feasible medium-term prospects. It’s unlikely moral enhancement heralds any metamorphic post-human utopia (or dystopia), but that doesn’t mean dismissing its transformative potential. In one sense, we should be wary of transhumanist fervour about the salvatory promise of new technology. By the same token we must resist technofear and alarmist efforts to balk social and scientific progress. Emerging methods will continue to shape morality in subtle and not-so-subtle ways – the critical steps are spotting and scaffolding these with robust ethical discussion, public engagement, and reasonable policy options. Steering a bright and judicious course requires that we pilot the possibilities of morally-disruptive technologies.
Podcast: The Friday Five - your health research roundup
The Friday Five is a new podcast series in which Leaps.org covers five breakthroughs in research over the previous week that you may have missed. There are plenty of controversies and ethical issues in science – and we get into many of them in our online magazine – but there’s also plenty to be excited about, and this news roundup is focused on inspiring scientific work to give you some momentum headed into the weekend.
Covered in this week's Friday Five:
- Puffer fish chemical for treating chronic pain
- Sleep study on the health benefits of waking up multiples times per night
- Best exercise regimens for reducing the risk of mortality aka living longer
- AI breakthrough in mapping protein structures with DeepMind
- Ultrasound stickers to see inside your body