After their remarkable success against Covid-19, mRNA vaccines are enjoying a moment in the sun — which scientists hope will light the way to a similar breakthrough in cancer treatment.
Although in development for years, it was the coronavirus emergency that showed mRNA's potential to the world, making the technology a household name and opening a lucrative market for drug companies.
Cancer, malaria and HIV/Aids are among the diseases that researchers hope to tackle by borrowing the body’s natural protein-building software.
The idea is to use this software, or messenger RNA (mRNA), to create exact replicas of a known enemy such as the distinctive spike of the novel coronavirus.
That way, the immune system learns to recognise its foe and will be ready for battle when it meets the real thing — the principle behind vaccination since Edward Jenner’s earliest experiments in 1796.
Cancer brings at least two complications, says Dr Samuel Godfrey of Cancer Research UK: the enemy is not a foreign invader but a diseased human cell and there are at least 200 types of the disease.
The first is a problem because the body is generally wired not to fight its own cells, Dr Godfrey told The National. And the second means that any off-the-shelf vaccine could prepare the body only for certain cancer cases.
“Our whole body is programmed to try to stop us attacking ourselves. It’s quite easy for cancer to hijack that process,” he said.
Nonetheless, an mRNA vaccine could be a “really valuable, exciting tool” if used in concert with other treatments, and could potentially be on the market within two to three years.
“It’s part of the puzzle rather than the complete solution by itself,” he said, but “still a very exciting field".
Vaccine after diagnosis
While Covid-19 brought about a race between vaccines and the virus, shots against cancer would probably look different.
Pre-emptively vaccinating a whole population to prevent cancer is less likely because of the many varieties of the illness and the fact that it builds up gradually rather than arriving in one moment of infection.
But while a Covid vaccine would come too late to save someone who is already in hospital, a patient diagnosed with cancer would be given an injection at that point.
This is potentially an exciting development because mRNA “gives the opportunity to very much personalise a vaccine”, said Dr Godfrey.
“Every disease can be as genetically unique as the person that’s got it,” he said. “Let’s say if I developed a tumour — I could have my tumour sequenced and then from that someone could design an mRNA vaccine specifically for me.”
In the first instance, this might be prohibitively expensive to do at scale, but the costs could come down as technology improved.
The first human genome to be sequenced by scientists was part of a project that cost about $2.7 billion, but the process can now be repeated for less than $1,000.
Hopes for mRNA vaccines are especially high because their success against Covid-19 has attracted unprecedented interest from investors and the public.
The pandemic also brought vaccines to market at unprecedented speed, showing how a process that can often take 10 or 15 years could be compressed into less than 12 months.
BioNTech, the German company which helped to develop the first fully tested Covid vaccine, gave the first dose of one potential cancer vaccine in a trial last June. It also has plans to use mRNA to fight malaria.
The company's founders, scientists Professor Ugur Sahin and Dr Ozlem Tureci, initially set it up in 2008 with cancer research as their main priority.
Moderna, another coronavirus success story, is keen on the idea of custom-made cancer vaccines and is in the early phase of trials for its own candidate.
The US National Cancer Institute said there were dozens of trials under way for various types of the disease, including pancreatic and colorectal cancer.
“It is very exciting from a science perspective the fact that so much research is going on. It’s only going to be good for science in general,” said Dr Godfrey.
“As technology advances, it could well be that in the future we’re in a situation where we’re able to uniquely prime people’s immune systems towards specific qualities of a cancer, and mRNA would be a hugely fast tool for doing that.”
Immunity puzzles
Even if these trials prove successful, however, immunotherapy does not always work.
A cancer cell looks much less foreign than a virus, meaning vaccines must latch on to parts of the tumour that mark it out from healthy cells.
Cancer is adept at exploiting this and finding ways round the immune system, said Dr Godfrey, including by deactivating the white blood cells that come to attack it.
This means that training the body to recognise a particular kind of cancer is no guarantee that it will successfully banish the tumour.
As a result, an mRNA vaccine may work better in some people than for others, said Dr Godfrey, with some patients potentially finding it very effective and others using it to complement immunotherapy or relying on other treatments.
“It’s such a tricky target. We need a whole range of approaches,” he said. “I’m excited about it, but moderating it with: it’s not going to be the death of cancer.”
The other difference with Covid-19 is this: instead of humanity starting on the back foot, existing cancer treatments already mean that half of patients in England and Wales survive for a decade or more after diagnosis.
“Already, we’ve actually come such a long way,” Dr Godfrey said. “It is research like this and this kind of push forward which is eventually going to take us the rest of the way where we don’t see anyone having their life cut short by cancer.”
