Scientists are making progress to create a one-time therapy that would permanently lower LDL cholesterol to prevent heart attacks caused by high LDL.
Later this year, Verve Therapeutics of Cambridge, Ma., will initiate Phase 1 clinical trials to test VERVE-101, a new medication that, if successful, will employ gene editing to significantly reduce low-density lipoprotein cholesterol, or LDL.
LDL is sometimes referred to as the “bad” cholesterol because it collects in the walls of blood vessels, and high levels can increase chances of a heart attack, cardiovascular disease or stroke. There are approximately 600,000 heart attacks per year due to blood cholesterol damage in the United States, and heart disease is the number one cause of death in the world. According to the CDC, a 10 percent decrease in total blood cholesterol levels can reduce the incidence of heart disease by as much as 30 percent.
Verve’s Founder and CEO, Sekar Kathiresan, spent two decades studying the genetic basis for heart attacks while serving as a professor of medicine at Harvard Medical School. His research led to two critical insights.
“One is that there are some people that are naturally resistant to heart attack and have lifelong, low levels of LDL,” the cardiologist says. “Second, there are some genes that can be switched off that lead to very low LDL cholesterol, and individuals with those genes switched off are resistant to heart attacks.”
Kathiresan and his team formed a hypothesis in 2016 that if they could develop a medicine that mimics the natural protection that some people enjoy, then they might identify a powerful new way to treat and ultimately prevent heart attacks. They launched Verve in 2018 with the goal of creating a one-time therapy that would permanently lower LDL and eliminate heart attacks caused by high LDL.
"Imagine a future where somebody gets a one-time treatment at the time of their heart attack or before as a preventive measure," says Kathiresan.
The medication is targeted specifically for patients who have a genetic form of high cholesterol known as heterozygous familial hypercholesterolemia, or FH, caused by expression of a gene called PCSK9. Verve also plans to develop a program to silence a gene called ANGPTL3 for patients with FH and possibly those with or at risk of atherosclerotic cardiovascular disease.
FH causes cholesterol to be high from birth, reaching levels of 200 to 300 milligrams per deciliter. Suggested normal levels are around 100 to 129 mg/dl, and anything above 130 mg/dl is considered high. Patients with cardiovascular disease usually are asked to aim for under 70 mg/dl, but many still have unacceptably high LDL despite taking oral medications such as statins. They are more likely to have heart attacks in their 30s, 40s and 50s, and require lifelong LDL control.
The goal for drug treatments for high LDL, Kathiresan says, is to reduce LDL as low as possible for as long as possible. Physicians and researchers also know that a sizeable portion of these patients eventually start to lose their commitment to taking their statins and other LDL-controlling medications regularly.
“If you ask 100 patients one year after their heart attack what fraction are still taking their cholesterol-lowering medications, it’s less than half,” says Kathiresan. “So imagine a future where somebody gets a one-time treatment at the time of their heart attack or before as a preventive measure. It’s right in front of us, and it’s something that Verve is looking to do.”
In late 2020, Verve completed primate testing with monkeys that had genetically high cholesterol, using a one-time intravenous injection of VERVE-101. It reduced the monkeys’ LDL by 60 percent and, 18 months later, remains at that level. Kathiresan expects the LDL to stay low for the rest of their lives.
Verve’s gene editing medication is packaged in a lipid nanoparticle to serve as the delivery mechanism into the liver when infused intravenously. The drug is absorbed and makes its way into the nucleus of the liver cells.
Verve’s program targeting PCSK9 uses precise, single base, pair base editing, Kathiresan says, meaning it doesn't cut DNA like CRISPR gene editing systems do. Instead, it changes one base, or letter, in the genome to a different one without affecting the letters around it. Comparing it to a pencil and eraser, he explains that the medication erases out a letter A and makes it a letter G in the A, C, G and T code in DNA.
“We need to continue to advance our approach and tools to make sure that we have the absolute maximum ability to detect off-target effects,” says Euan Ashley, professor of medicine and genetics at Stanford University.
By making that simple change from A to G, the medication switches off the PCSK9 gene, automatically lowering LDL cholesterol.
“Once the DNA change is made, all the cells in the liver will have that single A to G change made,” Kathiresan says. “Then the liver cells divide and give rise to future liver cells, but every time the cell divides that change, the new G is carried forward.”
Additionally, Verve is pursuing its second gene editing program to eliminate ANGPTL3, a gene that raises both LDL and blood triglycerides. In 2010, Kathiresan's research team learned that people who had that gene completely switched off had LDL and triglyceride levels of about 20 and were very healthy with no heart attacks. The goal of Verve’s medication will be to switch off that gene, too, as an option for additional LDL or triglyceride lowering.
“Success with our first drug, VERVE-101, will give us more confidence to move forward with our second drug,” Kathiresan says. “And it opens up this general idea of making [genomic] spelling changes in the liver to treat other diseases.”
The approach is less ethically concerning than other gene editing technologies because it applies somatic editing that affects only the individual patient, whereas germline editing in the patient’s sperm or egg, or in an embryo, gets passed on to children. Additionally, gene editing therapies receive the same comprehensive amount of testing for side effects as any other medicine.
“We need to continue to advance our approach and tools to make sure that we have the absolute maximum ability to detect off-target effects,” says Euan Ashley, professor of medicine and genetics at Stanford University and founding director of its Center for Inherited Cardiovascular Disease. Ashley and his colleagues at Stanford’s Clinical Genomics Program and beyond are increasingly excited about the promise of gene editing.
“We can offer precision diagnostics, so increasingly we’re able to define the disease at a much deeper level using molecular tools and sequencing,” he continues. “We also have this immense power of reading the genome, but we’re really on the verge of taking advantage of the power that we now have to potentially correct some of the variants that we find on a genome that contribute to disease.”
He adds that while the gene editing medicines in development to correct genomes are ahead of the delivery mechanisms needed to get them into the body, particularly the heart and brain, he’s optimistic that those aren’t too far behind.
“It will probably take a few more years before those next generation tools start to get into clinical trials,” says Ashley, whose book, The Genome Odyssey, was published last year. “The medications might be the sexier part of the research, but if you can’t get it into the right place at the right time in the right dose and not get it to the places you don’t want it to go, then that tool is not of much use.”
Medical experts consider knocking out the PCSK9 gene in patients with the fairly common genetic disorder of familial hypercholesterolemia – roughly one in 250 people – a potentially safe approach to gene editing and an effective means of significantly lowering their LDL cholesterol.
Nurse Erin McGlennon has an Implantable Cardioverter Defibrillator and takes medications, but she is also hopeful that a gene editing medication will be developed in the near future.
Erin McGlennon
Mary McGowan, MD, chief medical officer for The Family Heart Foundation in Pasadena, CA, sees the tremendous potential for VERVE-101 and believes patients should be encouraged by the fact that this kind of research is occurring and how much Verve has accomplished in a relatively short time. However, she offers one caveat, since even a 60 percent reduction in LDL won’t completely eliminate the need to reduce the remaining amount of LDL.
“This technology is very exciting,” she said, “but we want to stress to our patients with familial hypercholesterolemia that we know from our published research that most people require several therapies to get their LDL down., whether that be in primary prevention less than 100 mg/dl or secondary prevention less than 70 mg/dl, So Verve’s medication would be an add-on therapy for most patients.”
Dr. Kathiresan concurs: “We expect our medicine to lower LDL cholesterol by about 60 percent and that our patients will be on background oral medications, including statins that lower LDL cholesterol.”
Several leading research centers are investigating gene editing treatments for other types of cardiovascular diseases. Elizabeth McNally, Elizabeth Ward Professor and Director at the Center for Genetic Medicine at Northwestern University’s Feinberg School of Medicine, pursues advanced genetic correction in neuromuscular diseases such as Duchenne muscular dystrophy and spinal muscular atrophy. A cardiologist, she and her colleagues know these diseases frequently have cardiac complications.
“Even though the field is driven by neuromuscular specialists, it’s the first therapies in patients with neuromuscular diseases that are also expected to make genetic corrections in the heart,” she says. “It’s almost like an afterthought that we’re potentially fixing the heart, too.”
Another limitation McGowan sees is that too many healthcare providers are not yet familiar with how to test patients to determine whether or not they carry genetic mutations that need to be corrected. “We need to get more genetic testing done,” she says. “For example, that’s the case with hypertrophic cardiomyopathy, where a lot of the people who probably carry that diagnosis and have never been genetically identified at a time when genetic testing has never been easier.”
One patient who has been diagnosed with hypertrophic cardiomyopathy also happens to be a nurse working in research at Genentech Pharmaceutical, now a member of the Roche Group, in South San Francisco. To treat the disease, Erin McGlennon, RN, has an Implantable Cardioverter Defibrillator and takes medications, but she is also hopeful that a gene editing medication will be developed in the near future.
“With my condition, the septum muscles are just growing thicker, so I’m on medicine to keep my heart from having dangerous rhythms,” says McGlennon of the disease that carries a low risk of sudden cardiac death. “So, the possibility of having a treatment option that can significantly improve my day-to-day functioning would be a major breakthrough.”
McGlennon has some control over cardiovascular destiny through at least one currently available technology: in vitro fertilization. She’s going through it to ensure that her children won't express the gene for hypertrophic cardiomyopathy.
A worker tends to a rural farm in Hanoi, Vietnam, where technology is making it easier to harvest an ancient fern called Azolla. Some scientists and farmers view Azolla as a solution to our modern-day agricultural and environmental challenges.
This “Arctic Azolla event” had devastating impacts on marine life. To date, scientists are trying to figure out how it ended. But they documented that the extraordinary event cooled down the Arctic by at least 40 degrees Fahrenheit — effectively freezing the poles and triggering several cycles of ice ages. “This carbon dioxide sequestration changed the climate from greenhouse to white house,” says Jonathan Bujak, a paleontologist who has researched the Arctic through expeditions since 1973.
Some farmers and scientists, such as Bujak, are looking to this ancient fern, which manipulated the Earth’s climate around 49 million years ago with its insatiable appetite for carbon dioxide, as a potential solution to our modern-day agricultural and environmental challenges. “There is no other plant like Azolla in the world,” says Bujak.
Decoding the Azolla plant
Azolla lives in symbiosis with a cyanobacterium called Anabaena that made the plant’s leaf cavities its permanent home at an early stage in Earth's history. This close relationship with Anabaena enables Azolla to accomplish a feat that is impossible for most plants: directly splitting dinitrogen molecules that make up 78 percent of the Earth’s atmosphere.
A dinitrogen molecule consists of two nitrogen atoms tightly locked together in one of the strongest bonds in nature. The semi-aquatic fern’s ability to split nitrogen, called nitrogen-fixing, made it a highly revered plant in East Asia. Rice farmers used Azolla as a biofertilizer since the 11th century in Vietnam and China.
For decades, scientists have attempted to decode Azolla’s evolution. Cell biologist Francisco Carrapico, who worked at the University of Lisbon, has analyzed this distinctive symbiosis since the 1980s. To his amazement, in 1991, he found that bacteria are the third partner of the Azolla-Anabaena symbiosis.
“Azolla and Anabaena cannot survive without each other. They have co-evolved for 80 million years, continuously exchanging their genetic material with each other,” says Bujak, co-author of The Azolla Story, which he published with his daughter, Alexandra Bujak, an environmental scientist. Three different levels of nitrogen fixation take place within the plant, as Anabaena draws down as much as 2,200 pounds of atmospheric nitrogen per acre annually.
“Using Azolla to mitigate climate change might sound a bit too simple. But that is not the case,” Bujak says. “At a microscopic level, extremely complicated biochemical reactions are constantly occurring inside the plant’s cells that machines or technology cannot replicate yet.”
In 2018, researchers based in the U.S. managed to sequence Azolla’s complete genome — which is four times larger than the human genome — through a crowdfunded study, further increasing our understanding of this plant. “Azolla is a superorganism that works efficiently as a natural biotechnology system that makes it capable of doubling in size within three to five days,” says Carrapico.
Making Azolla mainstream again in agriculture
While scientific groups in the Global North have been working towards unraveling the tiny fern’s inner workings, communities in the Global South are busy devising creative ways to return to their traditional agricultural roots by tapping into Azolla’s full potential.
Pham Gia Minh, an entrepreneur living in Hanoi, Vietnam, is one such citizen scientist who believes that Azolla could be a climate savior. More than two decades after working in finance and business development, Minh is now focusing on continuing his grandfather’s legacy, an agricultural scientist who conducted Azolla research until the 1950s. “Azolla is our family’s heritage,” says Minh.
Pham Gia Minh, an entrepreneur and citizen scientist in Hanoi, Vietnam, believes that Azolla could be a climate savior
Pham Gia Minh
Since the advent of chemical fertilizers in the early 1900s, farmers in Asia abandoned Azolla to save on time and labor costs. But rice farmers in the country went back to cultivating Azolla during the Vietnam War after chemical trade embargoes made chemical fertilizers far too expensive and inaccessible.
By 1973, Azolla cultivation in rice paddy fields was established on half a million hectares in Vietnam. By injecting nitrogen into the soil, Azolla improves soil fertility and also increases rice yields by at least 27 percent compared to urea. The plants can also reduce a farm’s methane emissions by 40 percent.
“Unfortunately, after 1985, chemical fertilizers became cheap and widely available in Vietnam again. So, farmers stopped growing Azolla because of the time-consuming and labor-intensive cultivation process,” says Minh.
Minh has invested in a rural farm where he is proving that modern technology can make the process less burdensome. He uses a pump and drying equipment for harvesting Azolla in a small pond, and he deploys a drone for spraying insecticides and fertilizers on the pond at regular intervals.
As Azolla lacks phosphorus, farmers in developing countries still find it challenging to let go of chemical fertilizers completely. Still, Minh and Bujak say that farmers can use Azolla instead of chemical fertilizers after mixing it with dung.
In the last few years, the fern’s popularity has been growing in other developing countries like India, Palestine, Indonesia, the Philippines, and Bangladesh, where local governments and citizens are trying to re-introduce Azolla integrated farming by growing the ferns in small ponds.
Replacing soybeans with Azolla
In Ecuador, Mariano Montano Armijos, a former chemical engineer, has worked with Azolla for more than 20 years. Since 2008, he has shared resources and information for growing Azolla with 3,000 farmers in Ecuador. The farmers use the harvested plants as a bio-fertilizer and feed for livestock.
“The farmers do not use urea anymore,” says Armijos. “This goes against the conventional agricultural practices of using huge amounts of synthetic nitrogen on a hectare of rice or corn fields.”
He insists that Azolla’s greatest strength is that it is a rich source of proteins, making it highly nutritious for human beings as well. After growing Azolla on a small scale in ponds, Armijos and his business partner, Ivan Noboa, are now building a facility for cultivating the ferns as a superfood on an industrial scale.
According to Armijos, one hectare of Azolla in Ecuador can produce seven tons of proteins. Whereas soybeans produce only one ton of protein per hectare. “If we switch to Azolla, it could help in reducing deforestation in the Amazon. But taming Azolla and turning it into a crop is not easy,” he adds.
Henriette Schluepmann, a molecular plant biologist at Utrecht University in the Netherlands, believes that Azolla could replace soybeans and chemical fertilizers someday — only if researchers can achieve yield stability in controlled environments over long durations.
“In a country like the Netherlands that is surrounded by water with high levels of phosphates, it makes sense to grow Azolla as a substitute for soybeans,” says Schluepmann. “For that to happen, we need massive investments to understand these ferns’ reproductive system and how to replicate that within aquaculture systems on a large scale.”
Pollution control and carbon sequestration
Currently, Schluepmann and her team are growing Azolla in a plant nursery or closed system before transferring the ferns to flooded fields. So far, they have been able to continuously grow Azolla without any major setbacks for a total of 155 days. Taking care of these plants’ well-being is an uphill struggle.
Unlike most plants, Azolla does not grow from seeds because it contains female and male spores that tend to split instead of reproducing. To add to that, growing Azolla on a large scale in controlled environments makes the floating plants extremely vulnerable to insect infestations and fungi attacks.
“Even though it is easier to grow Azolla on a non-industrial scale, the long and tedious cultivation process is often in conflict with human rights,” she says. Farms in developing countries such as Indonesia sometimes use child labor for cultivating Azolla.”
History has taught us that the uncontrolled growth of Azolla plants deprives marine ecosystems of sunlight and chokes life underneath them. But researchers like Schluepmann and Bujak are optimistic that even on a much smaller scale, Azolla can put up a fight against human-driven climate change.
Schluepmann discovered an insecticide that can control Azolla blooms. But in the wild, this aquatic fern grows relentlessly in polluted rivers and lakes and has gained a notorious reputation as an invasive weed. Countries like Portugal and the UK banned Azolla after experiencing severe blooms in rivers that snuffed out local marine life.
“Azolla has been misunderstood as a nuisance. But in reality, it is highly beneficial for purifying water,” says Bujak. Through a process called phytoremediation, Azolla locks up pollutants like excess nitrogen and phosphorus and stops toxic algal blooms from occurring in rivers and lakes.
A 2018 study found that Azolla can decrease nitrogen and phosphorus levels in wastewater by 33 percent and 40.5 percent, respectively. While harmful algae like phytoplankton produce toxins and release noxious gases, Azolla automatically blocks any toxins that its cyanobacteria, Anabaena, might produce.
“In our labs, we observed that Azolla works effectively in treating wastewater,” explains Schluepmann. “Once we gain a better understanding of Azolla aquaculture, we can also use it for carbon capture and storage. But in Europe, we would have to use the entire Baltic Sea to make a difference.”
Planting massive amounts of these prehistoric ferns in any of the Northern great water bodies is out of the question. After all, history has taught us that the uncontrolled growth of Azolla plants deprives marine ecosystems of sunlight and chokes life underneath them. But researchers like Schluepmann and Bujak are optimistic that even on a much smaller scale, Azolla can put up a fight against human-driven climate change.
Traditional carbon capture and storage methods are not only expensive but also inefficient and could increase air pollution. According to Bujak’s estimates, Azolla can sequester 10 metric tonnes of carbon dioxide per hectare annually, which is 10 times the average capacity of grasslands.
“Anyone can set up their own DIY carbon capture and storage system by growing Azolla in shallow water. After harvesting and compressing the plants, carbon dioxide gets stored permanently,” says Bujak.
He envisions scaling up this process by setting up “Azolla hubs” in mega-cities where the plants are grown in shallow trays stacked on top of each other with vertical farming systems built within multi-story buildings. The compressed Azolla plants can then be converted into a biofuel, fertilizer, livestock feed, or biochar for sequestering carbon dioxide.
“Using Azolla to mitigate climate change might sound a bit too simple. But that is not the case,” Bujak adds. “At a microscopic level, extremely complicated biochemical reactions are constantly occurring inside the plant’s cells that machines or technology cannot replicate yet.”
Through Azolla, scientists hope to work with nature by tapping into four billion years of evolution.
