Would a Broad-Spectrum Antiviral Drug Stop the Pandemic?
The refocusing of medical research to COVID-19 is unprecedented in human history. Seven months ago, we barely were aware that the virus existed, and now a torrent of new information greets us each day online.
There are many unanswered questions about COVID-19, but perhaps the most fascinating is whether we even need to directly go after the virus itself.
Clinicaltrials.gov, the most commonly used registry for worldwide medical research, listed 1358 clinical trials on the disease, including using scores of different potential drugs and multiple combinations, when I first wrote this sentence. The following day that number of trials had increased to 1409. Laboratory work to prepare for trials presents an even broader and untabulated scope of activity.
Most trials will fail or not be as good as what has been discovered in the interim, but the hope is that a handful of them will yield vaccines for prevention and treatments to attenuate and ultimately cure the deadly infection.
The first impulse is to grab whatever drugs are on the shelf and see if any work against the new foe. We know their safety profiles and they have passed some regulatory hurdles. Remdesivir is the first to register some success against SARS-CoV-2, the virus behind the disease. The FDA has granted it expedited-use status, pending presentation of data that may lead to full approval of the drug.
Most observers see it as a treatment that might help, but not one that by itself is likely to break the back of the pandemic. Part of that is because it is delivered though IV infusion, which requires hospitalization, and as with most antiviral drugs, appears to be most beneficial when started early in disease. "The most effective products are going to be that ones that are developed by actually understanding more about this coronavirus," says Margaret "Peggy" Hamburg, who once led the New York City public health department and later the U.S. Food and Drug Administration.
Combination therapy that uses different drugs to hit a virus at different places in its life cycle have proven to work best in treating HIV and hepatitis C, and likely will be needed with this virus as well. Most viruses are simply too facile at evolving resistance to a single drug, and so require multiple hits to keep them down.
Laboratory work suggests that other drugs, both off-the-shelf and in development, particularly those to treat HIV and hepatitis, might also be of some benefit against SARS-CoV-2. But the number of possible drug combinations is mind-bogglingly large and the capacity to test them all right now is limited.
Broad-Spectrum Antivirals
Viruses are simple quasi-life forms. Effective treatments are more likely to be specific to a given virus, or at best its close relatives. That is unlike bacteria, where broad-spectrum antibiotics often can be used against common elements like the bacterial cell wall, or can disrupt quorum sensing signals that bacteria use to function as biofilms.
More than a decade ago, virologist Benhur Lee's lab at UCLA (now at Mt. Sinai in New York City) stumbled upon a broad-spectrum antiviral approach that seemed to work against all enveloped viruses they tested. The list ranged from the common flu to HIV to Ebola.
Other researchers grabbed this lead to develop a compound that worked quite well in cell cultures, but when they tried it in animals, a frustrating snag emerged; the compound needed to be activated by light. As the greatest medical need is to counter viruses deep inside the body, the research was put on the shelf. So Lee was surprised to learn recently that a company has inquired about rights to develop the compound not as a treatment but as a possible disinfectant. The tale illustrates both the unanticipated difficulties of drug development and that one never knows how knowledge ultimately might be put to use.
Remdesivir is a failed drug for Ebola that has found new life with SARS-CoV-2. It targets polymerase, an enzyme that the virus produces to use host cell machinery to replicate itself, and since the genetic sequence of polymerase is very similar among all of the different coronaviruses, scientists hope that the drug might be useful against known members of the family and others that might emerge in the future.
But nature isn't always that simple. Viral RNA is not a two-dimensional assemblage of genes in a flat line on a table; rather it is a three-dimensional matrix of twists and turns where a single atom change within the polymerase gene or another gene close by might change the orientation of the RNA or a molecular arm within it and block a drug from accessing the targeted binding site on the virus. One drug might need to bind to a large flat surface, while another might be able to slip a dagger-like molecular arm through a space in the matrix to reach its binding target.
That is why a broad-spectrum antiviral is so hard to develop, and why researchers continue to work on a wide variety of compounds that target polymerase as a binding site.
Additionally, it has taken us decades to begin to recognize the unintended consequences of broad-spectrum rather than narrowly targeted antibiotics on the gut microbiome and our overall health. Will a similar issue potentially arise in using a broad-spectrum antiviral?
"Off-target side effects are always of concern with drugs, and antivirals are no exception," says Yale University microbiologist Ben Chen. He believes that "most" bacteriophages, the viruses that infect bacteria and likely help to maintain stability in the gut microbial ecosystem, will shrug off such a drug. However, a few families of phages share polymerases that are similar to those found in coronaviruses. While the immediate need for treatment is great, we will have to keep a sharp eye out for unanticipated activity in the body's ecosystem from new drugs.
Is an Antiviral Needed?
There are many unanswered questions about COVID-19, but perhaps the most fascinating is whether we even need to directly go after the virus itself. Mounting evidence indicates that up to half the people who contract the infection don't seem to experience significant symptoms and their immune system seems to clear the virus.
The most severe cases of COVID-19 appear to result from an overactive immune response that damages surrounding tissue. Perhaps downregulating that response will be sufficient to reduce the disease burden. Several studies are underway using approved antibodies that modulate an overly active immune response.
One of the most surprising findings to date involves the monoclonal antibody leronlimab. It was originally developed to treat HIV infection and works modestly well there, but other drugs are better and its future likely will be mainly to treat patients who have developed resistance to those other drugs.
The response has been amazingly different in patients in the U.S. with COVID-19 who were given emergency access to leronlimab – two injections a week apart, though the company believes that four might be better. The immune response and inflammatory cytokines declined significantly, T cell counts were maintained, and surprisingly the amount of virus in the blood declined too. Data from the first ten patients is available in a preprint while the paper undergoes peer review for publication. Data from an additional fifty patients will be added.
"We got lucky and hit the bulls' eye from a mile away," says Jay Lalezari, the chief science officer of Cytodyn, the company behind leronlimab. Dr. Jay, as he is widely known in San Francisco, built an adoring fan base running many of the early-phase drug studies for treating HIV. While touting leronlimab, Lalezari suspects it might best be used as part of a combination therapy.
The small, under-capitalized firm is struggling for attention in the vast pool of therapies proposed to treat COVID-19. It faces the added challenge of gaining acceptance because it is based on a different approach and mechanism of action, which involves a signaling molecule important to immune cell migration, than what most researchers and the FDA anticipate as being relevant to counter SARS-CoV-2.
Common Issues
All of the therapeutics under development will face some common sets of issues. One is the pressure to have results yesterday, because people are dying. The rush to disseminate information "make me worry that certain things will become entrenched as truth, even in the scientific community, without the actual scientific documentation that ordinarily scientists would demand," says Hamburg.
"It is becoming increasingly clear that the biggest problem for drug and vaccine makers is not which therapeutics or vaccine platform to pursue."
Lack of standardization in assays and laboratory operations makes it difficult to compare results between labs studying SARS-CoV-2. In the long run, this will slow down the iterative process of research that builds upon what has gone before. And the shut down of supply chains, from chemicals to cell lines to animals to air shipment, has the potential to further hobble research.
Almost all researchers consult with the FDA in putting together their clinical trials. But the agency is overwhelmed with the surge of activity in the field, and is even less capable of handling novel approaches that fall outside of its standard guidance.
"It is becoming increasingly clear that the biggest problem for drug and vaccine makers is not which therapeutics or vaccine platform to pursue. It is that conventional clinical development paths are far too lengthy and cumbersome to address the current public health threat," John Hodgson wrote in Nature Biotechnology.
Another complicating factor with this virus is the broad range of organ and tissue types it can infect. That has implications for potential therapies, which often vary in their ability to enter different tissues. At a minimum, it complicates the drug development process.
Remdesivir has become the de facto standard of care. Ideally, clinical trials are conducted using the existing standard of care rather than a placebo as the control group. But shortages of the drug make that difficult and further inhibit learning what is the best treatment regimen for regular clinical care.
"Understandably, we all really want to respond to COVID-19 in a much, much more accelerated fashion," says Hamburg. But ultimately that depends upon "the reality of understanding the nature of the disease. And that is going to take a bit more time than we might like or wish."
[This article was originally published on June 8th, 2020 as part of a standalone magazine called GOOD10: The Pandemic Issue. Produced as a partnership among LeapsMag, The Aspen Institute, and GOOD, the magazine is available for free online.]
If you were one of the millions who masked up, washed your hands thoroughly and socially distanced, pat yourself on the back—you may have helped change the course of human history.
Scientists say that thanks to these safety precautions, which were introduced in early 2020 as a way to stop transmission of the novel COVID-19 virus, a strain of influenza has been completely eliminated. This marks the first time in human history that a virus has been wiped out through non-pharmaceutical interventions, such as vaccines.
The flu shot, explained
Influenza viruses type A and B are responsible for the majority of human illnesses and the flu season.
Centers for Disease Control
For more than a decade, flu shots have protected against two types of the influenza virus–type A and type B. While there are four different strains of influenza in existence (A, B, C, and D), only strains A, B, and C are capable of infecting humans, and only A and B cause pandemics. In other words, if you catch the flu during flu season, you’re most likely sick with flu type A or B.
Flu vaccines contain inactivated—or dead—influenza virus. These inactivated viruses can’t cause sickness in humans, but when administered as part of a vaccine, they teach a person’s immune system to recognize and kill those viruses when they’re encountered in the wild.
Each spring, a panel of experts gives a recommendation to the US Food and Drug Administration on which strains of each flu type to include in that year’s flu vaccine, depending on what surveillance data says is circulating and what they believe is likely to cause the most illness during the upcoming flu season. For the past decade, Americans have had access to vaccines that provide protection against two strains of influenza A and two lineages of influenza B, known as the Victoria lineage and the Yamagata lineage. But this year, the seasonal flu shot won’t include the Yamagata strain, because the Yamagata strain is no longer circulating among humans.
How Yamagata Disappeared
Flu surveillance data from the Global Initiative on Sharing All Influenza Data (GISAID) shows that the Yamagata lineage of flu type B has not been sequenced since April 2020.
Nature
Experts believe that the Yamagata lineage had already been in decline before the pandemic hit, likely because the strain was naturally less capable of infecting large numbers of people compared to the other strains. When the COVID-19 pandemic hit, the resulting safety precautions such as social distancing, isolating, hand-washing, and masking were enough to drive the virus into extinction completely.
Because the strain hasn’t been circulating since 2020, the FDA elected to remove the Yamagata strain from the seasonal flu vaccine. This will mark the first time since 2012 that the annual flu shot will be trivalent (three-component) rather than quadrivalent (four-component).
Should I still get the flu shot?
The flu shot will protect against fewer strains this year—but that doesn’t mean we should skip it. Influenza places a substantial health burden on the United States every year, responsible for hundreds of thousands of hospitalizations and tens of thousands of deaths. The flu shot has been shown to prevent millions of illnesses each year (more than six million during the 2022-2023 season). And while it’s still possible to catch the flu after getting the flu shot, studies show that people are far less likely to be hospitalized or die when they’re vaccinated.
Another unexpected benefit of dropping the Yamagata strain from the seasonal vaccine? This will possibly make production of the flu vaccine faster, and enable manufacturers to make more vaccines, helping countries who have a flu vaccine shortage and potentially saving millions more lives.
After his grandmother’s dementia diagnosis, one man invented a snack to keep her healthy and hydrated.
On a visit to his grandmother’s nursing home in 2016, college student Lewis Hornby made a shocking discovery: Dehydration is a common (and dangerous) problem among seniors—especially those that are diagnosed with dementia.
Hornby’s grandmother, Pat, had always had difficulty keeping up her water intake as she got older, a common issue with seniors. As we age, our body composition changes, and we naturally hold less water than younger adults or children, so it’s easier to become dehydrated quickly if those fluids aren’t replenished. What’s more, our thirst signals diminish naturally as we age as well—meaning our body is not as good as it once was in letting us know that we need to rehydrate. This often creates a perfect storm that commonly leads to dehydration. In Pat’s case, her dehydration was so severe she nearly died.
When Lewis Hornby visited his grandmother at her nursing home afterward, he learned that dehydration especially affects people with dementia, as they often don’t feel thirst cues at all, or may not recognize how to use cups correctly. But while dementia patients often don’t remember to drink water, it seemed to Hornby that they had less problem remembering to eat, particularly candy.
Where people with dementia often forget to drink water, they're more likely to pick up a colorful snack, Hornby found. alzheimers.org.uk
Hornby wanted to create a solution for elderly people who struggled keeping their fluid intake up. He spent the next eighteen months researching and designing a solution and securing funding for his project. In 2019, Hornby won a sizable grant from the Alzheimer’s Society, a UK-based care and research charity for people with dementia and their caregivers. Together, through the charity’s Accelerator Program, they created a bite-sized, sugar-free, edible jelly drop that looked and tasted like candy. The candy, called Jelly Drops, contained 95% water and electrolytes—important minerals that are often lost during dehydration. The final product launched in 2020—and was an immediate success. The drops were able to provide extra hydration to the elderly, as well as help keep dementia patients safe, since dehydration commonly leads to confusion, hospitalization, and sometimes even death.
Not only did Jelly Drops quickly become a favorite snack among dementia patients in the UK, but they were able to provide an additional boost of hydration to hospital workers during the pandemic. In NHS coronavirus hospital wards, patients infected with the virus were regularly given Jelly Drops to keep their fluid levels normal—and staff members snacked on them as well, since long shifts and personal protective equipment (PPE) they were required to wear often left them feeling parched.
In April 2022, Jelly Drops launched in the United States. The company continues to donate 1% of its profits to help fund Alzheimer’s research.