7 New Insights about the Frontrunner U.S. Vaccine Candidate
A vaccine from Moderna could be available as early as January, Fauci recently said.
Earlier this year, biotech company Moderna broke world records for speed in vaccine development. Their researchers translated the genetic code of the coronavirus into a vaccine candidate in just 42 days.
We're about to expand our safety data in Phase II.
Phase I of the clinical trial started in Seattle on March 16th, with the already-iconic image of volunteer Jennifer Haller calmly receiving the very first dose.
Instead of traditional methods, this vaccine uses a new -- and so far unproven -- technology based on synthetic biology: It hijacks the software of life – messenger RNA – to deliver a copy of the virus's genetic sequence into cells, which, in theory, triggers the body to produce antibodies to fight off a coronavirus infection.
U.S. National Institute of Allergy and Infectious Diseases Director Anthony Fauci called the vaccine's preclinical data "impressive" and told National Geographic this week that a vaccine could be ready for general use as early as January.
The Phase I trial has dosed 45 healthy adults. Phase II trials are about to start, enrolling around 600 adults. Pivotal efficacy trials would follow soon thereafter, bankrolled in collaboration with the government office BARDA (Biomedical Advanced Research and Development Authority).
Today, the chief medical officer of Moderna, Tal Zaks, answered burning questions from the public in a webinar hosted by STAT. Here's an edited and condensed summary of his answers.
1) When will a vaccine become available?
We expect to have data in early summer about the antibody levels from our mRNA vaccine. At the same time, we can measure the antibody levels of people who have had the disease, and we should be able to measure the ability of those antibodies to prevent disease.
We will not yet know if the mRNA vaccine works to prevent disease, but we could soon talk about a potential for benefit. We don't yet know about risk. We're about to expand our safety data in Phase II.
In the summer, there is an expectation that we will be launching pivotal trials, in collaboration with government agencies that are helping fund the research. The trials would be launched with the vaccine vs. a placebo with the goal of establishing: How many cases can we show we prevented with the vaccine?
This is determined by two factors: How big is the trial? And what's the attack rate in the population we vaccinate? The challenge will be to vaccinate in the areas where the risk of infection is still high in the coming months, and we're able to vaccinate and demonstrate fewer infections compared to a placebo. If the disease is happening faster in a given area, you will be able to see an outcome faster. Potentially by the end of the year, we will have the data to say if the vaccine works.
Will that be enough for regulatory approval? The main question is: When will we cross the threshold for the anticipated benefit of a presumed vaccine to be worth the risk?
There is a distinction between approval for those who need it most, like the elderly. Their unmet need and risk/benefit is not the same as it is for younger adults.
My private opinion: I don't think it's a one-size-fits-all. It will be a more measured stance.
2) Can you speed up the testing process with challenge studies, where volunteers willingly get infected?
It's a great question and I applaud the people who ask it and I applaud those signing up to do it. I'm not sure I am a huge fan, for both practical and ethical reasons. The devil is in the details. A challenge study has to show us a vaccine can prevent not just infection but prevent disease. Otherwise, how do I know the dose in the challenge study is the right dose? If you take 100 young people, 90 of them will get mild or no disease. Ten may end up in hospital and one in the ICU.
Also, the timeline. Can it let you skip Phase II of large efficacy trial? The reality for us is that we are about to start Phase II anyway. It would be months before a challenge trial could be designed. And ethically: everybody agrees there is a risk that is not zero of having very serious disease. To justify the risk, we have to be sure the benefit is worth it - that it actually shrunk the timeline. To just give us another data point, I find it hard to accept.
This technology allows us to scale up manufacturing and production.
3) What was seen preclinically in the animal models with Moderna's mRNA vaccines?
We have taken vaccines using our technology against eight different viruses, including two flu strains. In every case, in the preclinical model, we showed we could prevent disease, and when we got to antibody levels, we got the data we wanted to see. In doses of 25-100 micrograms, that usually ends up being a sweet spot where we see an effect. It's a good place as to the expectation of what we will see in Phase I trials.
4) Why is Moderna pursuing an mRNA virus instead of a traditional inactivated virus or recombinant one? This is an untried technology.
First, speed matters in a pandemic. If you have tech that can move much quicker, that makes a difference. The reason we have broken world records is that we have invested time and effort to be ready. We're starting from a platform where it's all based on synthetic biology.
Second, it's fundamental biology - we do not need to make an elaborate vaccine or stick a new virus in an old virus, or try to make a neutralizing but not binding virus. Our technology is basically mimicking the virus. All life works on making proteins through RNA. We have a biological advantage by teaching the immune system to do the right thing.
Third, this technology allows us to scale up manufacturing and production. We as a company have always seen this ahead of us. We invested in our own manufacturing facility two years ago. We have already envisioned scale up on two dimensions. Lot size and vaccines. Vaccines is the easier piece of it. If everybody gets 100 micrograms, it's not a heck of a lot. Prior to COVID, our lead program was a CMV (Cytomegalovirus) vaccine. We had envisioned launching Phase III next year. We had been already well on the path to scale up when COVID-19 caught us by surprise. This would be millions and millions of doses, but the train tracks have been laid.
5) People tend to think of vaccines as an on-off switch -- you get a vaccine and you're protected. But efficacy can be low or high (like the flu vs. measles vaccines). How good is good enough here for protection, and could we need several doses?
Probably around 50-60 percent efficacy is good enough for preventing a significant amount of disease and decreasing the R0. We will aim higher, but it's hard to estimate what degree of efficacy to prepare for until we do the trial. (For comparison, the average flu vaccine efficacy is around 50 percent.)
We anticipate a prime boost. If our immune system has never seen a virus, you can show you're getting to a certain antibody level and then remind the immune system (with another dose). A prime boost is optimal.
My only two competitors are the virus and the clock.
6) How would mutations affect a vaccine?
Coronaviruses tend to mutate the least compared to other viruses but it's entirely possible that it mutates. The report this week about those projected mutations on the spike protein have not been predicted to alter the critical antibodies.
As we scale up manufacturing, the ability to plug in a new genetic sequence and get a new vaccine out there will be very rapid.
For flu vaccine, we don't prove efficacy every year. If we get to the same place with an mRNA vaccine, we will just change the sequence and come out with a new vaccine. The path to approval would be much faster if we leverage the totality of efficacy data like we do for flu.
7) Will there be more than one vaccine and how will they be made available?
I hope so, I don't know. The path to making these available will go through a public-private partnership. It's not your typical commercial way of deploying a vaccine. But my only two competitors are the virus and the clock. We need everybody to be successful.
How mRNA Could Revolutionize Medicine
In November 2020, messenger RNA catapulted into the public consciousness when the first COVID-19 vaccines were authorized for emergency use. Around the same time, an equally groundbreaking yet relatively unheralded application of mRNA technology was taking place at a London hospital.
Over the past two decades, there's been increasing interest in harnessing mRNA — molecules present in all of our cells that act like digital tape recorders, copying instructions from DNA in the cell nucleus and carrying them to the protein-making structures — to create a whole new class of therapeutics.
Scientists realized that artificial mRNA, designed in the lab, could be used to instruct our cells to produce certain antibodies, turning our bodies into vaccine-making factories, or to recognize and attack tumors. More recently, researchers recognized that mRNA could also be used to make another groundbreaking technology far more accessible to more patients: gene editing. The gene-editing tool CRISPR has generated plenty of hype for its potential to cure inherited diseases. But delivering CRISPR to the body is complicated and costly.
"Most gene editing involves taking cells out of the patient, treating them and then giving them back, which is an extremely expensive process," explains Drew Weissman, professor of medicine at the University of Pennsylvania, who was involved in developing the mRNA technology behind the COVID-19 vaccines.
But last November, a Massachusetts-based biotech company called Intellia Therapeutics showed it was possible to use mRNA to make the CRISPR system inside the body, eliminating the need to extract cells out of the body and edit them in a lab. Just as mRNA can instruct our cells to produce antibodies against a viral infection, it can also teach them to produce the two molecular components that make up CRISPR — a guide molecule and a cutting protein — to snip out a problem gene.
"The pandemic has really shown that not only are mRNA approaches viable, they could in certain circumstances be vastly superior to more traditional technologies."
In Intellia's London-based clinical trial, the company applied this for the first time in a patient with a rare inherited liver disease known as hereditary transthyretin amyloidosis with polyneuropathy. The disease causes a toxic protein to build up in a person's organs and is typically fatal. In a company press release, Intellia's president and CEO John Leonard swiftly declared that its mRNA-based CRISPR therapy could usher in a "new era of potential genome editing cures."
Weissman predicts that turning CRISPR into an affordable therapy will become the next major frontier for mRNA over the coming decade. His lab is currently working on an mRNA-based CRISPR treatment for sickle cell disease. More than 300,000 babies are born with sickle cell every year, mainly in lower income nations.
"There is a FDA-approved cure, but it involves taking the bone marrow out of the person, and then giving it back which is prohibitively expensive," he says. It also requires a patient to have a matched bone marrow done. "We give an intravenous injection of mRNA lipid nanoparticles that target CRISPR to the bone marrow stem cells in the patient, which is easy, and much less expensive."
Cancer Immunotherapy
Meanwhile, the overwhelming success of the COVID-19 vaccines has focused attention on other ways of using mRNA to bolster the immune system against threats ranging from other infectious diseases to cancer.
The practicality of mRNA vaccines – relatively small quantities are required to induce an antibody response – coupled with their adaptable design, mean companies like Moderna are now targeting pathogens like Zika, chikungunya and cytomegalovirus, or CMV, which previously considered commercially unviable for vaccine developers. This is because outbreaks have been relatively sporadic, and these viruses mainly affect people in low-income nations who can't afford to pay premium prices for a vaccine. But mRNA technology means that jabs could be produced on a flexible basis, when required, at relatively low cost.
Other scientists suggest that mRNA could even provide a means of developing a universal influenza vaccine, a goal that's long been the Holy Grail for vaccinologists around the world.
"The mRNA technology allows you to pick out bits of the virus that you want to induce immunity to," says Michael Mulqueen, vice president of business development at eTheRNA, a Belgium-based biotech that's developing mRNA-based vaccines for malaria and HIV, as well as various forms of cancer. "This means you can get the immune system primed to the bits of the virus that don't vary so much between strains. So you could actually have a single vaccine that protects against a whole raft of different variants of the same virus, offering more universal coverage."
Before mRNA became synonymous with vaccines, its biggest potential was for cancer treatments. BioNTech, the German biotech company that collaborated with Pfizer to develop the first authorized COVID-19 vaccine, was initially founded to utilize mRNA for personalized cancer treatments, and the company remains interested in cancers ranging from melanoma to breast cancer.
One of the major hurdles in treating cancer has been the fact that tumors can look very different from one person to the next. It's why conventional approaches, such as chemotherapy or radiation, don't work for every patient. But weaponizing mRNA against cancer primes the immune cells with the tumor's specific genetic sequence, training the patient's body to attack their own unique type of cancer.
"It means you're able to think about personalizing cancer treatments down to specific subgroups of patients," says Mulqueen. "For example, eTheRNA are developing a renal cell carcinoma treatment which will be targeted at around 20% of these patients, who have specific tumor types. We're hoping to take that to human trials next year, but the challenge is trying to identify the right patients for the treatment at an early stage."
Repairing Damaged mRNA
While hopes are high that mRNA could usher in new cancer treatments and make CRISPR more accessible, a growing number of companies are also exploring an alternative to gene editing, known as RNA editing.
In genetic disorders, the mRNA in certain cells is impaired due to a rogue gene defect, and so the body ceases to produce a particular vital protein. Instead of permanently deleting the problem gene with CRISPR, the idea behind RNA editing is to inject small pieces of synthetic mRNA to repair the existing mRNA. Scientists think this approach will allow normal protein production to resume.
Over the past few years, this approach has gathered momentum, as some researchers have recognized that it holds certain key advantages over CRISPR. Companies from Belgium to Japan are now looking at RNA editing to treat all kinds of disorders, from Huntingdon's disease, to amyotrophic lateral sclerosis, or ALS, and certain types of cancer.
"With RNA editing, you don't need to make any changes to the DNA," explains Daniel de Boer, CEO of Dutch biotech ProQR, which is looking to treat rare genetic disorders that cause blindness. "Changes to the DNA are permanent, so if something goes wrong, that may not be desirable. With RNA editing, it's a temporary change, so we dose patients with our drugs once or twice a year."
Last month, ProQR reported a landmark case study, in which a patient with a rare form of blindness called Leber congenital amaurosis, which affects the retina at the back of the eye, recovered vision after three months of treatment.
"We have seen that this RNA therapy restores vision in people that were completely blind for a year or so," says de Boer. "They were able to see again, to read again. We think there are a large number of other genetic diseases we could go after with this technology. There are thousands of different mutations that can lead to blindness, and we think this technology can target approximately 25% of them."
Ultimately, there's likely to be a role for both RNA editing and CRISPR, depending on the disease. "I think CRISPR is ideally suited for illnesses where you would like to permanently correct a genetic defect," says Joshua Rosenthal of the Marine Biology Laboratory in Chicago. "Whereas RNA editing could be used to treat things like pain, where you might want to reset a neural circuit temporarily over a shorter period of time."
Much of this research has been accelerated by the COVID-19 pandemic, which has played a major role in bringing mRNA to the forefront of people's minds as a therapeutic.
"The pandemic has really shown that not only are mRNA approaches viable, they could in certain circumstances be vastly superior to more traditional technologies," says Mulqueen. "In the future, I would not be surprised if many of the top pharma products are mRNA derived."
"Making Sense of Science" is a monthly podcast that features interviews with leading medical and scientific experts about the latest developments and the big ethical and societal questions they raise. This episode is hosted by science and biotech journalist Emily Mullin, summer editor of the award-winning science outlet Leaps.org.