Researchers advance drugs that treat pain without addiction
New therapies are using creative approaches that target the body’s sensory neurons, which send pain signals to the brain.
Opioids are one of the most common ways to treat pain. They can be effective but are also highly addictive, an issue that has fueled the ongoing opioid crisis. In 2020, an estimated 2.3 million Americans were dependent on prescription opioids.
Opioids bind to receptors at the end of nerve cells in the brain and body to prevent pain signals. In the process, they trigger endorphins, so the brain constantly craves more. There is a huge risk of addiction in patients using opioids for chronic long-term pain. Even patients using the drugs for acute short-term pain can become dependent on them.
Scientists have been looking for non-addictive drugs to target pain for over 30 years, but their attempts have been largely ineffective. “We desperately need alternatives for pain management,” says Stephen E. Nadeau, a professor of neurology at the University of Florida.
A “dimmer switch” for pain
Paul Blum is a professor of biological sciences at the University of Nebraska. He and his team at Neurocarrus have created a drug called N-001 for acute short-term pain. N-001 is made up of specially engineered bacterial proteins that target the body’s sensory neurons, which send pain signals to the brain. The proteins in N-001 turn down pain signals, but they’re too large to cross the blood-brain barrier, so they don’t trigger the release of endorphins. There is no chance of addiction.
When sensory neurons detect pain, they become overactive and send pain signals to the brain. “We wanted a way to tone down sensory neurons but not turn them off completely,” Blum reveals. The proteins in N-001 act “like a dimmer switch, and that's key because pain is sensation overstimulated.”
Blum spent six years developing the drug. He finally managed to identify two proteins that form what’s called a C2C complex that changes the structure of a subunit of axons, the parts of neurons that transmit electrical signals of pain. Changing the structure reduces pain signaling.
“It will be a long path to get to a successful clinical trial in humans," says Stephen E. Nadeau, professor of neurology at the University of Florida. "But it presents a very novel approach to pain reduction.”
Blum is currently focusing on pain after knee and ankle surgery. Typically, patients are treated with anesthetics for a short time after surgery. But anesthetics usually only last for 4 to 6 hours, and long-term use is toxic. For some, the pain subsides. Others continue to suffer after the anesthetics have worn off and start taking opioids.
N-001 numbs sensation. It lasts for up to 7 days, much longer than any anesthetic. “Our goal is to prolong the time before patients have to start opioids,” Blum says. “The hope is that they can switch from an anesthetic to our drug and thereby decrease the likelihood they're going to take the opioid in the first place.”
Their latest animal trial showed promising results. In mice, N-001 reduced pain-like behaviour by 90 percent compared to the control group. One dose became effective in two hours and lasted a week. A high dose had pain-relieving effects similar to an opioid.
Professor Stephen P. Cohen, director of pain operations at John Hopkins, believes the Neurocarrus approach has potential but highlights the need to go beyond animal testing. “While I think it's promising, it's an uphill battle,” he says. “They have shown some efficacy comparable to opioids, but animal studies don't translate well to people.”
Nadeau, the University of Florida neurologist, agrees. “It will be a long path to get to a successful clinical trial in humans. But it presents a very novel approach to pain reduction.”
Blum is now awaiting approval for phase I clinical trials for acute pain. He also hopes to start testing the drug's effect on chronic pain.
Learning from people who feel no pain
Like Blum, a pharmaceutical company called Vertex is focusing on treating acute pain after surgery. But they’re doing this in a different way, by targeting a sodium channel that plays a critical role in transmitting pain signals.
In 2004, Stephen Waxman, a neurology professor at Yale, led a search for genetic pain anomalies and found that biologically related people who felt no pain despite fractures, burns and even childbirth had mutations in the Nav1.7 sodium channel. Further studies in other families who experienced no pain showed similar mutations in the Nav1.8 sodium channel.
Scientists set out to modify these channels. Many unsuccessful efforts followed, but Vertex has now developed VX-548, a medicine to inhibit Nav1.8. Typically, sodium ions flow through sodium channels to generate rapid changes in voltage which create electrical pulses. When pain is detected, these pulses in the Nav1.8 channel transmit pain signals. VX-548 uses small molecules to inhibit the channel from opening. This blocks the flow of sodium ions and the pain signal. Because Nav1.8 operates only in peripheral nerves, located outside the brain, VX-548 can relieve pain without any risk of addiction.
"Frankly we need drugs for chronic pain more than acute pain," says Waxman.
The team just finished phase II clinical trials for patients following abdominoplasty surgery and bunionectomy surgery.
After abdominoplasty surgery, 76 patients were treated with a high dose of VX-548. Researchers then measured its effectiveness in reducing pain over 48 hours, using the SPID48 scale, in which higher scores are desirable. The score for Vertex’s drug was 110.5 compared to 72.7 in the placebo group, whereas the score for patients taking an opioid was 85.2. The study involving bunionectomy surgery showed positive results as well.
Waxman, who has been at the forefront of studies into Nav1.7 and Nav1.8, believes that Vertex's results are promising, though he highlights the need for further clinical trials.
“Blocking Nav1.8 is an attractive target,” he says. “[Vertex is] studying pain that is relatively simple and uniform, and that's key to having a drug trial that is informative. But the study needs to be replicated and frankly we need drugs for chronic pain more than acute pain. If this is borne out by additional studies, it's one important step in a journey.”
Vertex will be launching phase III trials later this year.
Finding just the right amount of Nerve Growth Factor
Whereas Neurocarrus and Vertex are targeting short-term pain, a company called Levicept is concentrating on relieving chronic osteoarthritis pain. Around 32.5 million Americans suffer from osteoarthritis. Patients commonly take NSAIDs, or non-steroidal anti-inflammatory drugs, but they cannot be taken long-term. Some take opioids but they aren't very effective.
Levicept’s drug, Levi-04, is designed to modify a signaling pathway associated with pain. Nerve Growth Factor (NGF) is a neurotrophin: it’s involved in nerve growth and function. NGF signals by attaching to receptors. In pain there are excess neurotrophins attaching to receptors and activating pain signals.
“What Levi-04 does is it returns the natural equilibrium of neurotrophins,” says Simon Westbrook, the CEO and founder of Levicept. It stabilizes excess neurotrophins so that the NGF pathway does not signal pain. Levi-04 isn't addictive since it works within joints and in nerves outside the brain.
Westbrook was initially involved in creating an anti-NGF molecule for Pfizer called Tanezumab. At first, Tanezumab seemed effective in clinical trials and other companies even started developing their own versions. However, a problem emerged. Tanezumab caused rapidly progressive osteoarthritis, or RPOA, in some patients because it completely removed NGF from the system. NGF is not just involved in pain signalling, it’s also involved in bone growth and maintenance.
Levicept has found a way to modify the NGF pathway without completely removing NGF. They have now finished a small-scale phase I trial mainly designed to test safety rather than efficacy. “We demonstrated that Levi-04 is safe and that it bound to its target, NGF,” says Westbrook. It has not caused RPOA.
Professor Philip Conaghan, director of the Leeds Institute of Rheumatic and Musculoskeletal Medicine, believes that Levi-04 has potential but urges the need for caution. “At this early stage of development, their molecule looks promising for osteoarthritis pain,” he says. “They will have to watch out for RPOA which is a potential problem.”
Westbrook starts phase II trials with 500 patients this summer to check for potential side effects and test the drug’s efficacy.
There is a real push to find an effective alternative to opioids. “We have a lot of work to do,” says Professor Waxman. “But I am confident that we will be able to develop new, much more effective pain therapies.”
A Single Blood Test May Soon Replace Your Annual Physical
The measurement of proteins in one blood test could provide a comprehensive snapshot of a person's health in the near future.
For all the excitement over "personalized medicine" in the last two decades, its promise has not fully come to pass. Consider your standard annual physical.
Scientists have measured thousands of proteins from a single blood test to assess many individualized health conditions at once.
Your doctor still does a blood test to check your cholesterol and gauge your risk for heart disease by considering traditional risk factors (like smoking, diabetes, blood pressure) — an evaluation that has not changed in decades.
But a high-risk number alone is not enough to tell accurately whether you will suffer from heart disease. It just reflects your risk compared to population-level averages. In other words, not every person with elevated "bad" cholesterol will have a heart attack, so how can doctors determine who truly needs to give up the cheeseburgers and who doesn't?
Now, an emerging area of research may unlock some real-time answers. For the first time, as reported in the journal Nature Medicine last week, scientists have measured thousands of proteins from a single blood test to assess many individualized health conditions at once, including liver and kidney function, diabetes risk, body fat, cardiopulmonary fitness, and even smoking and alcohol consumption. Proteins can give a clear snapshot of how your body is faring at any given moment, as well as a sneak preview at what diseases may be lurking under the surface.
"Years from now," says study co-author Peter Ganz of UCSF, "we will probably be looking back on this paper as a milestone in personalized medicine."
We spoke to Ganz about the significance of this milestone. Our interview has been edited and condensed.
Is this the first study of its kind?
Yes, it is. This is a study where we measured 5,000 proteins at once to look for patterns that could either predict the risk of future diseases or inform the current state of health. Previous to this, people have measured typically one protein at a time, and some of these individual proteins have made it into clinical practice.
An example would be a protein called C-reactive protein, which is a measure of inflammation and is used sometimes in cardiology to predict the risk of future heart attacks. But what's really new is this scale. We wanted to get away from just focusing on one problem that the patient may have at a time, whether it's heart disease or kidney disease, and by measuring a much greater number of proteins, the hope is that we could inform the health of ultimately just about every organ in the body or every tissue. It's a step forward for what I would call "a one-stop shop."
"I'm very excited about personalized medicine through proteins as opposed to genes because you get both the nature and nurture."
Three things get me excited about this. One is the convenience for the patient of a single test to determine many different diseases. The second thing is the healthcare cost savings. We estimated what the cost would be to get these 11 healthcare measures that we reported on using traditional testing and the cost was upwards of 3,000 British pounds. And even though I don't know for sure what the cost of the protein tests would ultimately be, [it could come down to about $50 to $100].
The last thing is that the measurement of proteins is part of what people have called personalized medicine or precision medicine. If you look at risk factors across the population, it may not apply to individuals. In contrast, proteins are downstream of risk factors. So proteins actually tell us whether the traditional risk factors have set in motion the necessary machinery to cause disease. Proteins are the worker bees that regulate what the human body does, and so if you can find some anomalies in the proteins, that may inform us if a disease is likely to be ongoing even in its earliest stages.
Does protein testing have advantages over genetic testing for predicting future health risks?
The problem with genomics is that genes usually don't take care of the environment. It's a blueprint, but your blueprint has no idea what you will be exposed to during your lifetime in terms of the environment and lifestyle that you may choose and medications that you may be on. These are things that proteins can account for. I'm very excited about personalized medicine through proteins as opposed to genes because you get both the nature and nurture as opposed to genomics, which only gives you nature but doesn't account for anything else.
Proteins can also be tracked over time and that's not something you can do with genes. So if your behavior improves, your genes won't change, but your proteins will.
Could this new test become a regular feature of your annual physical?
That's the idea. This would be basically almost a standalone test that you could have done every year. And hopefully you wouldn't need other tests to complement this. This could be your yearly physical.
How much more does it need to be validated before it can enter the clinic and patients can trust the results?
This was a proof-of concept study. To really make this useful, we need to expand from 11 measures of health to a hundred or more health insights, to cover the whole body. And we need to expand this to all racial groups. Three of the five centers in the study were European – all Caucasian – so it's one of our high priorities to find groups of patients with better representation of minorities.
When do you expect doctors to be routinely giving this test to patients?
Much closer to five years than 20 years. We're scaling up from 11 disease states to 100, and many of those studies are underway. Results should be done within three to five years.
Do you think insurance will cover it?
Good question. I have been approached by an insurance company that wanted to understand the product better – a major insurer, with the possibility that this could actually be cost saving.
I have to ask you a curveball -- do you think that the downfall of Theranos will make consumers hesitant to trust a new technology that relies on using a single blood sample to screen for multiple health risks?
[Laughs] You're not the first person to ask me that today. I actually got a call from Elizabeth Holmes [in 2008 when I was at Harvard]. I met with her for an afternoon and met her team two more times. I gave them advice that they completely disregarded.
In many ways, what we do is diametrically opposite to Theranos. They had a culture of secrecy, and what we do is about openness. We publish, like this paper in Nature Medicine, to show the scientific details. Our supplement is much longer than the typical academic paper. We reveal everything we know. A lot of the research we do is funded by [the National Institutes of Health], and they have strict expectations about data sharing. So we agree to make the data available on a public website. If there is something we haven't done with the data, others can do it.
So you're saying that this is not another Theranos.
No, God forbid. We hope to be the opposite.
Kira Peikoff was the editor-in-chief of Leaps.org from 2017 to 2021. As a journalist, her work has appeared in The New York Times, Newsweek, Nautilus, Popular Mechanics, The New York Academy of Sciences, and other outlets. She is also the author of four suspense novels that explore controversial issues arising from scientific innovation: Living Proof, No Time to Die, Die Again Tomorrow, and Mother Knows Best. Peikoff holds a B.A. in Journalism from New York University and an M.S. in Bioethics from Columbia University. She lives in New Jersey with her husband and two young sons. Follow her on Twitter @KiraPeikoff.
We Pioneered a Technology to Save Millions of Poor Children, But a Worldwide Smear Campaign Has Blocked It
On left, a picture of white rice next to Golden Rice, and on right, a girl who lost one eye due to vitamin A deficiency.
In a few weeks it will be 20 years that we three have been working together. Our project has been independently praised as one of the most influential of all projects of the last 50 years.
Two of us figured out how to make rice produce a source of vitamin A, and the rice becomes a golden color instead of white.
The project's objectives have been admired by some and vilified by others. It has directly involved teams of highly motivated people from a handful of nations, from both the private and public sector. A book, dedicated to the three of us, has been written about our work. Nevertheless, success has, so far, eluded us all. The story of our thwarted efforts is a tragedy that we hope will soon – finally – reach a milestone of potentially profound significance for humanity.
So, what have we been working on, and why haven't we succeeded yet?
Food: everybody needs it, and many are fortunate enough to have enough, even too much of it. Food is a highly emotional subject on every continent and in every culture. For a healthy life our food has to provide energy, as well as, in very small amounts, minerals and vitamins. A varied diet, easily achieved and common in industrialised countries, provides everything.
But poor people in countries where rice is grown often eat little else. White rice only provides energy: no minerals or vitamins. And the lack of one of the vitamins, vitamin A, is responsible for killing around 4,500 poor children every day. Lack of vitamin A is the biggest killer of children, and also the main cause of irreversible childhood blindness.
Our project is about fixing this one dietary deficiency – vitamin A – in this one crop – rice – for this one group of people. It is a huge group though: half of the world's population live by eating a lot of rice every day. Two of us (PB & IP) figured out how to make rice produce a source of vitamin A, and the rice becomes a golden color instead of white. The source is beta-carotene, which the human body converts to vitamin A. Beta-carotene is what makes carrots orange. Our rice is called "Golden Rice."
The technology has been donated to assist those rice eaters who suffer from vitamin A deficiency ('VAD') so that Golden Rice will cost no more than white rice, there will be no restrictions on the small farmers who grow it, and nothing extra to pay for the additional nutrition. Very small amounts of beta-carotene will contribute to alleviation of VAD, and even the earliest version of Golden Rice – which had smaller amounts than today's Golden Rice - would have helped. So far, though, no small farmer has been allowed to grow it. What happened?
To create Golden Rice, it was necessary to precisely add two genes to the 30,000 genes normally present in rice plants. One of the genes is from maize, also known as corn, and the other from a commonly eaten soil bacterium. The only difference from white rice is that Golden Rice contains beta-carotene.
It has been proven to be safe to man and the environment, and consumption of only small quantities of Golden Rice will combat VAD, with no chance of overdosing. All current Golden Rice results from one introduction of these two genes in 2004. But the use of that method – once, 15 years ago - means that Golden Rice is a 'GMO' ('genetically modified organism'). The enzymes used in the manufacture of bread, cheese, beer and wine, and the insulin which diabetics take to keep them alive, are all made from GMOs too.
The first GMO crops were created by agri-business companies. Suspicion of the technology and suspicion of commercial motivations merged, only for crop (but not enzymes or pharmaceutical) applications of GMO technology. Activists motivated by these suspicions were successful in getting the 'precautionary principle' incorporated in an international treaty which has been ratified by 166 countries and the European Union – The Cartagena Protocol.
The equivalent of 13 jumbo jets full of children crashes into the ground every day and kills them all, because of vitamin A deficiency.
This protocol is the basis of national rules governing the introduction of GMO crops in every signatory country. Government regulators in, and for, each country must agree before a GMO crop can be 'registered' to be allowed to be used by the public in that country. Currently regulatory decisions to allow Golden Rice release are being considered in Bangladesh and the Philippines.
The Cartagena Protocol obliges the regulators in each country to consider all possible risks, and to take no account of any possible benefits. Because the anti-gmo-activists' initial concerns were principally about the environment, the responsibility for governments' regulation for GMO crops – even for Golden Rice, a public health project delivered through agriculture – usually rests with the Ministry of the Environment, not the Ministry of Health or the Ministry of Agriculture.
Activists discovered, before Golden Rice was created, that inducing fear of GMO food crops from 'multinational agribusinesses' was very good for generating donations from a public that was largely illiterate about food technology and production. And this source of emotionally charged donations would cease if Golden Rice was proven to save sight and lives, because Golden Rice represented the opposite of all the tropes used in anti-GMO campaigns.
Golden Rice is created to deliver a consumer benefit, it is not for profit – to multinational agribusiness or anyone else; the technology originated in the public sector and is being delivered through the public sector. It is entirely altruistic in its motivations; which activists find impossible to accept. So, the activists believed, suspicion against Golden Rice had to be amplified, Golden Rice had to be stopped: "If we lose the Golden Rice battle, we lose the GMO war."
Activism continues to this day. And any Environment Ministry, with no responsibility for public health or agriculture, and of course an interest in avoiding controversy about its regulatory decisions, is vulnerable to such activism.
The anti-GMO crop campaigns, and especially anti-Golden Rice campaigns, have been extraordinarily effective. If so much regulation by governments is required, surely there must be something to be suspicious about: 'There is no smoke without fire'. The suspicion pervades research institutions and universities, the publishers of scientific journals and The World Health Organisation, and UNICEF: even the most scientifically literate are fearful of entanglement in activist-stoked public controversy.
The equivalent of 13 jumbo jets full of children crashes into the ground every day and kills them all, because of VAD. Yet the solution of Golden Rice, developed by national scientists in the counties where VAD is endemic, is ignored because of fear of controversy, and because poor children's deaths can be ignored without controversy.
Perhaps more controversy lies in not taking scientifically based regulatory decisions than in taking them.
The tide is turning, however. 151 Nobel Laureates, a very significant proportion of all Nobel Laureates, have called on the UN, governments of the world, and Greenpeace to cease their unfounded vilification of GMO crops in general and Golden Rice in particular. A recent Golden Rice article commented, "What shocks me is that some activists continue to misrepresent the truth about the rice. The cynic in me expects profit-driven multinationals to behave unethically, but I want to think that those voluntarily campaigning on issues they care about have higher standards."
The recently published book has exposed the frustrating saga in simple detail. And the publicity from all the above is perhaps starting to change the balance of where controversy lies. Perhaps more controversy lies in not taking scientifically based regulatory decisions than in taking them.
But until they are taken, while there continues a chance of frustrating the objectives of the Golden Rice project, the antagonism will continue. And despite a solution so close at hand, VAD-induced death and blindness, and the misery of affected families, will continue also.
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