June 02 | 2022
Researchers advance drugs that treat pain without addiction
Sarah Philip is a London-based freelance journalist who writes about science, film and TV. You can follow her on Twitter @sarahph1lip.
New therapies are using creative approaches that target the body’s sensory neurons, which send pain signals to the brain.
Neurocarrus
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.”
Sarah Philip is a London-based freelance journalist who writes about science, film and TV. You can follow her on Twitter @sarahph1lip.
Vaccine passports, if required by businesses and universities, may give people a false sense of security, one expert cautions.
Vaccines are one of the greatest public health accomplishments of all time. For centuries, public health has relied on vaccinations to prevent and control disease outbreaks for a plethora of infectious scourges, with our crowning achievement being the successful eradication of smallpox.
The purpose of vaccine documentation is to provide proof of an individual's protection from either becoming infected or transmitting a vaccine-preventable disease. Vouching for these protections requires a firm knowledge about the epidemiology of the disease, as well as scientific knowledge concerning the efficacy of the vaccine. The vaccines we currently require be documented have met these tests; the vaccine for COVID-19 has not yet been proven to do so.
Let's acknowledge that the term "vaccine passport" is a poor choice of words. Passports are a legal travel document created by nations and governed by law for identification of the bearer to control entry and exit from nation states. They often serve as legal forms of identification and as a record of international travel. They are generally very sophisticated documents that have been created in a secure manner and may include a range of electronic and, in some cases, biometric measures such as fingerprints to ensure the holder is indeed who they say they are. Vaccine passports are medical documents used to document the vaccination status of an individual. They do not undergo the same level of administrative scrutiny and cannot be used to verify that the presenter is indeed the vaccinated individual. Some companies do have electronic methods to address concerns about verification; however, most people currently have paper records that can be easily falsified.
"Vaccine passports" as currently proposed risk giving people a false sense of security.
Successful disease control from vaccination programs relies on the ability to vaccinate at a level that prevents large-scale disease spread and the ability to rapidly identify the presence of disease outbreaks. It requires reliable, safe, and effective vaccines that are easily delivered in clinical and nonclinical settings. Keeping vaccination information as a part of the medical record, and even having a separate specialized vaccine record for personal use, is a time-honored tradition.
Keeping a vaccination record provides a method to keep track of the many shots one receives and serves as a visual reminder to help ensure the appropriate vaccine shot schedule is maintained for vaccines requiring multiple doses. The vaccine record, when combined with vaccine safety monitoring systems, serves as a mechanism to track adverse events to monitor and ensure the safety of vaccines as a consumer product. The record also serves as the official record of vaccination when required for administrative or legally prescribed purposes.
"Vaccine passports" as currently proposed risk giving people a false sense of security. In the case of the COVID-19 vaccines currently approved for use, many of the essential questions remain unanswered. While we do know the current three vaccines are highly protective against severe disease and death, and there is some evidence that these vaccinations do reduce infections and virus transmission of SARS-CoV-2, we do not yet know the full degree to which this occurs.
For example, we know there have been some cases of people that have been infected in close proximity to getting their full vaccination and rare cases of breakthrough reinfections. A breakthrough infection in a restaurant is a challenge for contact tracing, but an outbreak from a movie theater exposure or a baseball game could spark a major outbreak at our current level of vaccination. Current CDC guidance recommends continued mask wearing in order to address these concerns.
We also do not yet know how long the protections will last and if or when a booster or revaccination is required. In effect, it is too soon to know. Should an annual booster shot be required, then a vaccine passport would require annual updating, a process more frequent than renewal of a driver's license.
We also know that the current SARS-CoV-2 virus is mutating briskly. While the current approved vaccines have remained effective overall, there is evidence of some degree of degradation in vaccine effectiveness against some of the circulating strains. We also have sparse data on many of the other emerging strains of concern because we have not had the surveillance capacity in the U.S. to gain an adequate sense of how the virus is changing to fully align vaccine effectiveness with viral capabilities.
The risk of people misusing these "passports" is troubling. The potential for using these documents for hiring, firing or job limitation is a serious concern. Unvaccinated workers are at risk of this form of discrimination even from well-meaning employers or supervisors. Health insurers are prohibited by the Affordable Care Act from discriminating based on preexisting conditions, but they could probably charge a higher premium for unvaccinated individuals. There also is a risk of stigmatizing individuals who are not vaccinated or have left their vaccine documentation at home. Another concern: the opportunity to discriminate based on race, gender, sexual orientation, or religion, using one's vaccination status as an excuse.
These "passports" are being discussed as a "ticket verification" for entry to many activities, including dining at restaurants, flying domestically and/or internationally, going to movie theaters and sporting events, etc. These are all activities we already are doing at reduced levels and for which wearing a mask, hand hygiene and physical distancing are effective disease control practices. COVID-19 vaccines are indeed the measure that will make the ability to totally reopen our society complete, but we are not there yet. Documentation of one's COVID-19 vaccine status may be useful in selected situations in the future. That remains to be seen.
Finally, inadequate vaccine supply and disparities in vaccine delivery have created enormous challenges in providing equal access to vaccination. Also, the amount of misinformation, disinformation, and lingering vaccine hesitancy continue to limit the speed at which we will reach the level of vaccination of the population that would make this documentation meaningful. The requirement for "vaccine passports" is already alienating people who are opposed to vaccinations for a variety of reasons, paradoxically risking reduced vaccine uptake. This politicization of the vaccination effort is of concern. There are indeed people who, due to medical contraindications or legal exemptions, will not be vaccinated, and we do not yet have a national framework on how to address this.
Vaccine passports are not the solution for reopening our society — a robust vaccination program is. The requirement to document one's vaccination status for COVID-19 may one day have its place. For now, it is an idea whose time has not yet come.
Editor's Note: This op/ed is part of a "Big Question" series on the ethics of vaccine passports. Read the flip side argument here.
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Georges C. Benjamin, MD, is a well-known health policy leader, practitioner and administrator. He currently serves as the executive director of the American Public Health Association, the nation's oldest and largest organization of public health professionals. He is also a former secretary of health for the state of Maryland. Dr. Benjamin is a graduate of the Illinois Institute of Technology and the University Of Illinois College Of Medicine. He is board-certified in internal medicine, a Master of the American College of Physicians, a fellow of the National Academy of Public Administration, a fellow emeritus of the American College of Emergency Physicians, and a member of the National Academy of Medicine. He serves on several nonprofit boards such as Research!America, the Truth Foundation and, the Reagan-Udall Foundation. He is also a former member of the National Infrastructure Advisory Council, a council that advises the President on how best to assure the security of the nation’s critical infrastructure.
A digital health passport required by businesses and universities could help us get back to normal more quickly, one expert argues.
"Vaccine passports" are a system that requires proof of a COVID-19 vaccination as a condition of engaging in activities that pose a risk of transmitted SARS-CoV-2. Digital Health Passes (DHPs) are typically a smartphone application with a code that verifies whether someone has been vaccinated.
Vaccine passports could very much be in our future. Many businesses are implementing or planning to require proof of vaccination as a condition of returning to the workplace. Colleges and universities have announced vaccine requirements for students, staff, and faculty. It may not be long before the private sector requires a vaccination card or image to attend an entertainment or sporting event, to travel, or even to dine or shop indoors, at least in some venues.
But it's unlikely the federal government or the states will launch DHPs, at least not in the near-term. President Biden announced the White House has no intention of requiring proof of vaccination. While no state has mandated DHPs, New York is piloting its Excelsior Pass on a voluntary basis, partnering with IBM. Other nations are not so hesitant. Israel's "Green Pass" has gotten the nation back to normal in record time. And various countries and regions are planning DHPs, including the European Union and the United Kingdom. Foreign airlines are likely to require proof of vaccination as a condition of flying internationally.
DHPs could emerge as a way to get us back to normal more quickly, but are they ethical? Let's start with the law. The US Equal Opportunity Commission (EEOC) has specifically said that employers have the legal right to require proof of vaccination as a condition of returning to work. Colleges and universities already require several vaccines for students living in dorms. Hospitals and nursing homes often mandate influenza vaccinations. And, of course, all states require childhood vaccinations for school attendance. Vaccine passports are lawful but are they ethical? The short answer is "yes" but only if we ensure no one is left behind.
Vaccine passports "don't force anyone to be vaccinated against his or her will. They simply say to individuals that if you choose not to be vaccinated, you can't work or recreate in public spaces that risk transmission of the virus."
Why are vaccine passports ethical? Vaccines are a miracle of modern science, but they have become a political symbol, and a significant part of the population doesn't want to get a jab. The rare cases of blood clots associated with the Johnson & Johnson and AstraZeneca vaccines have only created more distrust.
Most opposition to vaccine passports hinges on the claim that they infringe personal autonomy and liberty. But this argument misses the point. Of course, every competent adult has the right to make decisions that affect his or her own health and safety. But no one has a right to infringe on the rights of others, such as by exposing them to a potentially serious or deadly infectious disease. An individual can't claim the right to attend a crowded event mask-less and unvaccinated. This was once accepted across the political spectrum. Conservative economists called it an "externality," that is a person has no right to harm others. The U.S. has lost the tradition of the common good. We have become so focused on our own individual rights that we forget about our ethical obligations to our neighbors and to our community.
In fact, DHPs actually don't force anyone to be vaccinated against his or her will. They simply say to individuals that if you choose not to be vaccinated, you can't work or recreate in public spaces that risk transmission of the virus.
DHPs also don't infringe on privacy. Again, everyone has the choice whether to show proof of vaccination. It isn't required. Moreover, DHPs may actually protect privacy because all they do is show whether or not you have been vaccinated. They don't disclose any other personal medical information. All of us actually have already had to show proof of vaccination as a condition of going to school. Thus, DHPs are well established in the United States.
But there is one ethical argument against DHPs that I find to be powerful, and that is equity. If we require proof of vaccination while doses are scarce, we will give the already privileged even more privilege. And that would be unconscionable. Thus, DHPs should not be implemented until everyone who wants a vaccine is able to get a vaccine. Equity isn't a side issue. It needs to be front and center.
As of today, all adults in the U.S. are eligible to get vaccinated, and President Biden has pledged that by the end of May there will be enough doses to vaccinate the entire U.S. population. It is a realistic promise. Once vaccines become plentiful, everyone should get their shot. All Food and Drug Administration authorized vaccines are highly safe and effective, even the Johnson & Johnson vaccine that the FDA has just put on pause.
Businesses have an economic incentive to require proof of vaccination. Very few of us would feel comfortable returning to our jobs, shops, theaters, or restaurants unless we feel safe. Businesses understand the duty to create safer places for work, recreation, and commerce.
One question has dominated national conversation since the pandemic began. "When will we get back to normal?" There is a deep human yearning to hug family and friends, see our work colleagues, recreate, and be entertained. One day we will have defeated this wily virus and get back to normal. But vaccine passports can help us get back to the things we love faster and more safely. As long as we don't leave anyone behind, using this miracle of modern science to make our lives better is both lawful and ethical.
Editor's Note: This op/ed is part of a "Big Question" series on the ethics of vaccine passports. Read the flip-side argument here.
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Lawrence O. Gostin is University Professor, Georgetown University’s highest academic rank, and Founding O’Neill Chair in Global Health Law. He directs the World Health Organization Center on National and Global Health Law. Gostin is Professor of Medicine at Georgetown University and Professor of Public Health at Johns Hopkins University. You can follow him on Twitter @lawrencegostin.