À la carte medicine
Dengue afflicts close to 400 million people a year. As much as one-third of the population of the world is at risk of contracting the disease. There are no vaccines for the disease and the most effective remedy seems to be to simply avoid being bitten by the Aedes aegypti mosquito.
Sometime back, a team of scientists in Australia discovered that when the Aedes mosquito is infected with the Wolbachia bacterium it is unable to carry the dengue virus. Wolbachia boosts the mosquito’s immune system and competes for nutrients like cholesterol and fatty acids that the virus needs in order to reproduce. They realised that if Wolbachia could be made to infect the mosquito population, that might offer a cure for dengue. In early 2011, the scientists tested this theory by releasing about 300,000 Wolbachia-infected mosquitoes into the wild. By May that same year, close to 90% of the mosquitoes in the locality had been infected with Wolbachia—effectively eliminating dengue in those towns—and proving that microbes can be successfully used to combat disease.
Medical treatment has always been mathematical—identifying deficiencies that cause our illnesses and replacing them with whatever it was that was missing—or identifying the alien pathogens in our bodies and using drugs to kill or eliminate them. It is only quite recently that we’ve come to realise that our bodies aren’t simple machines that can be fixed with the addition of a spare part or the removal of a defect. They are actually complex ecosystems that include the many millions of microbial organisms that live in symbiotic coexistence within our bodies.
This is the microbiome, a dynamic community of living organisms that makes us who we are, shaping our health, our mental functions and even our personality. It is a delicate yet remarkably resilient system that can collapse from something as innocuous as a change in diet but at the same time can defend the body from something as drastic as the introduction of a parasite. Antibiotics that are targeted at specific disease-inducing microbes often end up destroying large swathes of useful microbes as well. If used too often, they can have long-term consequences on the health of our microbiome.
There is no organ system in the body that is home to more microbes than the human gut. It is also, consequently, the organ system most commonly affected by variations in the microbiome. The Clostridium difficile (C-diff) bacterium inhabits this organ system and causes a particularly nasty strain of diarrhoea—one so aggressive and resistant to drugs that even when treated with strong antibiotics it reappears in a newer, more virulent form.
In recent years, after trying and failing to cure C-diff with traditional antibiotics, doctors have begun to use a 1,000-year-old technique called faecal microbiota transplant (or FMT) to treat this infection. The technique involves taking stools from a healthy donor, pulping it in a blender and injecting it into the gut of the patient so that the patient’s unhealthy gut ecosystem can be replaced by a functioning one. As revolting as FMT might sound, the results of this treatment are near miraculous—offering cure rates as high as 94% in really sick patients.
It is outcomes like these that have encouraged research into new methods of treatment aimed at maintaining the balance in our microbial families. These methods are designed to use carefully selected microbes to address the observed symptoms while at the same time ensuring that they function in harmony with our immune systems and the rest of our microbiome.
At the cutting edge of this research is the discipline of synthetic biology—the science of taking naturally occurring bacteria and modifying them to perform specific functions. As we perfect these techniques, we will eventually be able to engineer microbes to target cancer cells for elimination or convert toxic secretions into useful ones. It will give us the opportunity to localise treatments with millimetre precision so that they target the offending disease-causing cells without harming the healthy cells around them. In this future, visits to the doctor will be all about assessing the balance of our microbiome. Instead of using the broad spectrum drugs we are prescribed today, we will most likely be provided with a capsules of contextually designed probiotics, custom-made to re-balance our internal ecosystem.
We are particularly ill-equipped to regulate this new future of à la carte medicine. Our drug approval processes are designed to assess medicines that are intended to be used by vast swathes of the population. They are hopeless to deal with customised medicine.
This is the direction in which medicine is surely but steadily headed and, like it or not, if our regulators don’t gear up for this future, they will find themselves coming in its way.
Rahul Matthan is a partner at Trilegal. Ex Machina is a column on technology, law and everything in between.
His twitter handle is @matthan