breakthroughs

Researchers advance drugs that treat pain without addiction

Feature Story In The Lab
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.

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
Sarah Philip is a London-based freelance journalist who writes about science, film and TV. You can follow her on Twitter @sarahph1lip.
Leaps of the Past

How thousands of first- and second-graders saved the world from a deadly disease

History Feature Story
How thousands of first- and second-graders saved the world from a deadly disease

Although Jonas Salk has gone down in history for helping rid the world (almost) of polio, his revolutionary vaccine wouldn't have been possible without the world’s largest clinical trial – and the bravery of thousands of kids.

Photo by Charlein Gracia on Unsplash

Exactly 67 years ago, in 1955, a group of scientists and reporters gathered at the University of Michigan and waited with bated breath for Dr. Thomas Francis Jr., director of the school’s Poliomyelitis Vaccine Evaluation Center, to approach the podium. The group had gathered to hear the news that seemingly everyone in the country had been anticipating for the past two years – whether the vaccine for poliomyelitis, developed by Francis’s former student Jonas Salk, was effective in preventing the disease.

Polio, at that point, had become a household name. As the highly contagious virus swept through the United States, cities closed their schools, movie theaters, swimming pools, and even churches to stop the spread. For most, polio presented as a mild illness, and was usually completely asymptomatic – but for an unlucky few, the virus took hold of the central nervous system and caused permanent paralysis of muscles in the legs, arms, and even people’s diaphragms, rendering the person unable to walk and breathe. It wasn’t uncommon to hear reports of people – mostly children – who fell sick with a flu-like virus and then, just days later, were relegated to spend the rest of their lives in an iron lung.

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Sarah Watts

Sarah Watts is a health and science writer based in Chicago.

tech

Why you should (virtually) care

OPINION ESSAY Health
Why you should (virtually) care

Virtual-first care, or V1C, could increase the quality of healthcare and make it more patient-centric by letting patients combine in-person visits with virtual options such as video for seeing their care providers.

(© Elnur/Fotolia)

As the pandemic turns endemic, healthcare providers have been eagerly urging patients to return to their offices to enjoy the benefits of in-person care.

But wait.

The last two years have forced all sorts of organizations to be nimble, adaptable and creative in how they work, and this includes healthcare providers’ efforts to maintain continuity of care under the most challenging of conditions. So before we go back to “business as usual,” don’t we owe it to those providers and ourselves to admit that business as usual did not work for most of the people the industry exists to help? If we’re going to embrace yet another period of change – periods that don’t happen often in our complex industry – shouldn’t we first stop and ask ourselves what we’re trying to achieve?

Certainly, COVID has shown that telehealth can be an invaluable tool, particularly for patients in rural and underserved communities that lack access to specialty care. It’s also become clear that many – though not all – healthcare encounters can be effectively conducted from afar. That said, the telehealth tactics that filled the gap during the pandemic were largely stitched together substitutes for existing visit-based workflows: with offices closed, patients scheduled video visits for help managing the side effects of their blood pressure medications or to see their endocrinologist for a quarterly check-in. Anyone whose children slogged through the last year or two of remote learning can tell you that simply virtualizing existing processes doesn’t necessarily improve the experience or the outcomes!

But what if our approach to post-pandemic healthcare came from a patient-driven perspective? We have a fleeting opportunity to advance a care model centered on convenient and equitable access that first prioritizes good outcomes, then selects approaches to care – and locations – tailored to each patient. Using the example of education, imagine how effective it would be if each student, regardless of their school district and aptitude, received such individualized attention.

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Jennifer C. Goldsack & Linette Demers
Jennifer C. Goldsack co-founded and serves as the CEO of the Digital Medicine Society (DiMe), a 501(c)(3) non-profit organization dedicated to advancing digital medicine to optimize human health. Jennifer’s research focuses on applied approaches to the safe, effective, and equitable use of digital technologies to improve health, healthcare, and health research. She is a member of the Roundtable on Genomics and Precision Health at the National Academies of Science, Engineering and Medicine and serves on the World Economic Forum Global Leadership Council on mental health. Previously, Jennifer spent several years at the Clinical Trials Transformation Initiative (CTTI), a public-private partnership co-founded by Duke University and the FDA. There, she led development and implementation of several projects within CTTI’s Digital Program and was the operational co-lead on the first randomized clinical trial using FDA’s Sentinel System. Jennifer spent five years working in research at the Hospital of the University of Pennsylvania, first in Outcomes Research in the Department of Surgery and later in the Department of Medicine. More recently, she helped launch the Value Institute, a pragmatic research and innovation center embedded in a large academic medical center in Delaware. Jennifer earned her master’s degree in chemistry from the University of Oxford, England, her masters in the history and sociology of medicine from the University of Pennsylvania, and her MBA from the George Washington University. Additionally, she is a certified Lean Six Sigma Green Belt and a Certified Professional in Healthcare Quality. Jennifer is a retired athlete, formerly a Pan American Games Champion, Olympian, and World Championship silver medalist. ___________________________________________________________________________ Linette Demers leads IMPACT, a DiMe initiative dedicated to advancing high value, evidence-based virtual first care for patients, healthcare providers, and payers. Previously, Linette was responsible for commercialization, entrepreneurship and capital formation programs at Life Science Washington and WINGS Angels. Her 20 year career in healthcare spans strategy, business development, and population health management in oncology care at Fred Hutch, and management consulting at Sg2. Linette holds a PhD in Chemistry and a BS in Health Economics and Outcomes Research.