During this Covid-19 pandemic, many people have received – an mRNA vaccine, from the likes of Pfizer-BioNTech and Moderna. It’s considered a game-changer in medicine that has the potential to even provide a cure for cancers, HIV, tropical diseases, and even give us superhuman immunity.
Proteins are the ‘workhorses’ of the body. Nearly every function in the human body – both normal and disease-related – is carried out by one or many proteins. DNA (deoxyribonucleic acid) is a double-stranded molecule that stores the genetic instructions your body’s cells need to make proteins.
Messenger ribonucleic acid, or mRNA for short, is a single-stranded molecule that carries genetic code from DNA in a cell’s nucleus to ribosomes, the cell’s protein-making machinery. mRNA plays a vital role in human biology in a process known as protein synthesis. It contains the set of instructions by which cells make all proteins and send them to various parts of the body.
Using mRNA as a medicine is a fundamentally different approach than treating disease with other drug classes. Traditional vaccines work by injecting inactivated virus proteins called antigens, which stimulate the body’s immune system to recognise the virus when it reappears. The genius of mRNA vaccines is there’s no need to inject the antigen itself.
Once a virus is inside our cells, it releases its own RNA, tricking our hijacked cells into spewing out copies of the virus – in the form of viral proteins – that compromise our immune system. mRNA vaccines use the genetic sequence or “code” of the antigen translated into mRNA. It’s a ghost of the real thing, fooling the body into creating very real antibodies. The artificial mRNA itself then disappears, degraded by the body’s natural defenses including enzymes that break it down, leaving us with only the antibodies.
mRNA medicines take advantage of normal biological processes to express proteins and create a desired therapeutic effect. This enables the potential treatment of a broad spectrum of diseases, many of which cannot be addressed with current technologies.
Perhaps the first new mRNA vaccine to hit our shelves, however, will be for a more familiar foe – the flu. Influenza viruses are responsible for an estimated 290,000–650,000 deaths annually worldwide. “We’re most likely to see mRNA vaccines against influenza in the near future,” says Whitehead. “These mRNA vaccines have been in development for years, and clinical trials to date have been encouraging. There are currently five clinical trials for Influenza A, including one in phase two”. This could be just in time. Paul Hunter, a professor of health protection at the University of East Anglia in the UK who also consults for the WHO, has warned that some countries may be due an influenza epidemic that could lead to more fatalities than Covid-19.
Several pharmaceutical companies are also pursuing mRNA vaccines and treatments for cancer. Now, some investigators believe the success of the mRNA COVID-19 vaccines could help accelerate clinical research on mRNA vaccines to treat cancer. mRNA-based cancer treatment vaccines have been tested in small trials for nearly a decade, with some promising early results.
“Cancer cells will often have certain surface markers that the rest of the cells in your body don’t have,” says Anna Blakney assistant professor at the University of British Columbia, Canada. “You can train your immune system to recognise and kill those cells, just like you can train your immune system to recognise and kill a virus: it’s the same idea, you just figure out what proteins are on the surface of your tumour cells and use that as a vaccine”.
The idea of patient-specific, individualised medicine has been a tantalising prospect for years – this could be another door pushed wide open by mRNA, according to Blakney. In theory, “they take out your tumour, they sequence it, see what’s on the surface of it, and then they make a vaccine specifically for you”.
Dozens of clinical trials are testing mRNA treatment vaccines in people with various types of cancer, including pancreatic cancer, colorectal cancer, and melanoma. Some vaccines are being evaluated in combination with drugs that enhance the body’s immune response to tumors. But no mRNA cancer vaccine has been approved by the US Food and Drug Administration for use either alone or with other cancer treatments.
“mRNA vaccine technology is extremely promising for infectious diseases and may lead to new kinds of vaccines,” said Elad Sharon, M.D., M.P.H., of NCI’s Division of Cancer Treatment and Diagnosis. “For other applications, such as the treatment of cancer, research on mRNA vaccines also appears promising, but these approaches have not yet proven themselves.”
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