Many researchers have asked these questions, but, until now, not in connection with new medical treatments that increase the mutation rate of viruses or bacteria with the goal of eradicating them. Rather surprisingly, the person who did raise the question in this context was not a scientist, but a social media user with a lot of common sense. He was responding to an encouraging announcement at the height of the coronavirus pandemic from the pharmaceutical company Merck. The company had received emergency, fast-track approval from the US Food and Drug Administration for a new drug called molnupiravir, which tricks the SARS-CoV-2 virus into mutating so quickly that it kills itself off. The man’s logical response: Although in most cases it is clear that speeding up the mutation rate will be fatal for viruses, every so often viruses could benefit from the changes to their genome, which could give them improved capabilities – and then humans would encounter more dangerous strains of coronavirus and end up paying a heavy price for this evolutionary innovation.
Prof. Yitzhak Pilpel from the Weizmann Institute of Science’s Molecular Genetics Department saw that social media post and wondered: Is it possible that the drug has a very serious flaw that was overlooked during the development and approval process? “As far as I know,” Pilpel explains, “this is the first drug ever that was developed to kill the virus by accelerating the mutation rate as its key mechanism, and this could change the way that a lethal epidemic spreads. Since drug safety tests usually focus on their effect on the patients themselves – in other words, on the physiological safety of the drug – it seems that a need has arisen for a system that will test the safety of drugs from an entirely new perspective, which will impact the entire human population: evolutionary safety. Such a test would also be relevant for drugs – developed before molnupiravir – that also accelerate the mutation rate of viruses or bacteria, but do so as an unintended byproduct.”