With messenger RNA being pushed to the market in record time and Alnylam’s historic approval of an RNA interference drug, the field of RNA therapeutics is now moving faster than ever before.
Recently, both BioNTech and Moderna have generated enormous publicity as their Covid-19 vaccines edge closer to approval. Just today, BioNTech’s vaccine was greenlit in the UK, making it the first messenger RNA (mRNA) therapeutic to ever be approved, with vaccine rollouts expected to begin next week.
“The phenomenal success of the Covid-19 mRNA vaccine development will provide acceptance of this technology and increase the interest for the general public, patients, care providers, and investors alike,” said Thomas Thum, CSO and co-founder of Cardior Pharmaceuticals, a German biotech developing RNA drugs to treat heart failure.
The brand new technology behind these vaccines consists of providing our cells with the precise instructions they need to produce proteins of the Covid-19 virus, which trains the immune system to recognize and neutralize it. But this is not the only application of RNA technology.
Another form of RNA, called RNA interference (RNAi), is already in use to treat rare conditions by selectively turning off the expression of certain faulty genes into proteins. This month, the RNAi drug Oxlumo — developed by the US biotech Alnylam — was approved by the EMA and US FDA. It’s the first-ever treatment for the rare kidney condition primary hyperoxaluria.
In many ways, the rapid progress of mRNA vaccines demonstrates the RNA space was already poised to take off in a big way before the pandemic. According to Nicola Gray, an RNA expert and Professor at the University of Edinburgh, a combination of factors has prepared the RNA therapeutics space to be ready for prime time this year.
“I think what’s moved the space forward is that there’s been a lot of developments in things like stability of RNAs and delivery, that have allowed the transition from what everybody knew we could do in cells, which is really very powerful, to actually going to a whole organism.”
A long time coming
In the 1960s, mRNA was discovered to be instrumental for converting the DNA code into proteins, but decades passed before it could be considered as a potential therapeutic modality. In 1990, scientists showed that injecting mice with mRNA encoding a certain protein resulted in the animals producing the protein. This was the start of a long journey to get RNA therapeutics to the clinic.
Despite decades of research, RNA technologies have proven slow in making it to the market. “There’s been a sort of reluctance for people to get their heads into that space,” said Gray.
The first official RNA therapeutic was fomivirsen, developed by Ionis Pharmaceuticals (previously Isis Pharmaceuticals). Approved to treat cytomegalovirus retinitis in 1998, the drug — an antisense oligonucleotide — was later withdrawn because of low demand. Six years later, the FDA approved NeXstar Pharmaceuticals’ pegaptanib to treat wet age-related macular degeneration. The drug is an RNA aptamer, which blocks target proteins in a similar way to antibody drugs.
In 2006, RNA interference technology started to receive a lot of attention when its discoverers, Andrew Fire and Craig Mello, received the Nobel Prize of Medicine. However, it was not until 2018 that the first RNAi drug, Alnylam’s Onpattro (patisiran) was approved to treat the rare condition hereditary transthyretin-mediated amyloidosis.
While safety problems delayed the approval of the first RNAi drug, Alnylam has launched one such drug every year since then. In 2019 came Givlaari for treating a rare liver disease, and the approval of Oxlumo last month was its latest stride forward.
“The past few years have seen recognition of RNAi come on leaps and bounds and the insights we have obtained from Onpattro and Givlaari are now fueling a new chapter for this technology,” said Brendan Martin, the Acting Head of Alnylam in Canada, the Middle East, and Europe.
A good year for RNA therapeutics
The global pandemic has turned the life sciences industry on its head. The major mRNA developers Moderna, BioNTech, and CureVac were all focusing on developing cancer therapies and vaccines before diverting resources to the development of Covid-19 vaccines. Both BioNTech and Moderna broke records with the short time it took to submit for the approval of the vaccines.
“The speed of development and the compelling evidence for remarkable safety and efficacy in a wide-ranging population, will facilitate the development of novel drug or vaccine candidates making the R&D and approval process the new standard for the future, including for other areas of RNA therapeutics,” believes Thum.
|RNA technology||Companies to watch in 2021|
|Antisense RNA||Ionis Pharmaceuticals, Akcea Therapeutics, Sarepta Therapeutics|
|Small interfering RNA (siRNA)||Alnylam, Arrowhead Pharmaceuticals, Dicerna Pharmaceuticals, Silence Therapeutics|
|Messenger RNA (mRNA)||BioNTech, Moderna, CureVac, Arcturus Therapeutics|
|Micro RNA (miRNA)||Cardior Pharmaceuticals, miRagen Therapeutics|
But, would RNA therapeutics and vaccines have had such success this year if not for the pandemic?
“There were a lot of things that needed to be solved, like stability of RNAs and how to deliver them, and a lot of those things have come into place in recent years,” explained Gray. “What I can do in a cell is now moving towards what I can do in a whole organism. And that’s incredible.”
Historically, a key challenge in the field was delivering the RNA to the target cells. Lipid nanoparticles have also solved some delivery issues, as they can package the RNA so it can more easily move around the body. This is becoming more sophisticated now with increasing abilities to target specific organs and cells, regardless of where the therapy is injected.
“There are ways of doing that with control elements that take advantage of the natural regulatory mechanisms within those cells, and you sort of hijack and pirate those,” explained Gray.
Another challenge has been manufacturing at scale. However, in recent years many companies seem to have cracked this issue, and RNA manufacturing services are now part of the offering of many CDMO firms. One famous example is that of Tesla, which announced plans to develop RNA factories to distribute CureVac’s Covid-19 vaccine.
What’s next for the RNA field?
RNA medicines are having a good year, but what is next for the field? What is still needed to make these vaccines and therapeutics truly mainstream?
“One of the challenges with RNA vaccines, as they stand at the moment, is that they are not particularly thermally stable,” Gray noted.
“Some of the ones in clinical trials are using a [freeze-drying] procedure to combat this. Moderna’s is more thermally stable than BioNTech’s vaccine, but they also use several times more RNA in the dose, that means it’s going to be more expensive to make.”
One way to get around this is to use self-replicating RNA, a technology where the RNA drug is able to produce more copies of itself once inside the body. This concept is being trialed by US biotech Arcturus Therapeutics and also by researchers at Imperial College London for the development of Covid-19 vaccines. Both are at an earlier stage than those produced by BioNTech/Pfizer and Moderna, but could end up being cheaper to produce and equally viable in the long run.
This technology also has potential for other RNA therapeutics. “If you’re going to give somebody an injection, that RNA might last two-to-three days. But if you need six weeks to repair an organ, for instance, you don’t want to be injecting somebody every couple of days,” said Gray.
A lot of RNA medicines have focused on rare diseases and cancer until now, but they are starting to expand into other areas. For example, Cardior is working to treat heart failure with a new class of non-coding RNA drug, called microRNA (miRNA), that blocks many other RNA molecules that cause cardiovascular damage at once. Earlier this month, the drug showed signs of reducing heart damage in heart failure patients in a phase Ib trial.
Another form of RNA technology currently in development is RNA activation. The London-based company MiNA Therapeutics is using this technology to treat metabolic disease as well as cancer.
Getting regulatory authorities on board with new therapies can be a challenge, but it has become easier in recent years with both the EMA and FDA being open to collaboration and change. The speed of the trials carried out this year and the dominance of mRNA vaccines at the top of the table has certainly helped.
Both Thum and Gray believe the approvals in recent years and advances in manufacturing capacity, stand the RNA field in good stead.
“It’s taken a while for us to really have the tools to move forward, which has needed people from other disciplines to come in, for instance in the development of the lipid nanoparticles,” said Gray.
“Now the tools are there, the successes in preclinical work are there, and I think within the next 10 years, it’s likely that we’ll see more and more coming through to the clinic, and more acceptance of [RNA] as a valid set of technologies for the treatment of clinical problems.”
Cover illustration by Elena Resko, images via Shutterstock.