It’s an age-old problem in drug development: a compound that seems to exert its desired effects against cells in a Petri dish, but flops in vivo, either in animal models or, later, in humans. One common reason for such failures is how the body metabolizes drugs. Enzymes in the liver can break down molecules quickly, substantially limiting their potency. They might produce toxic metabolites in the process to boot.
If you could fortify the chemical bonds that hold those drugs together, thereby modulating the metabolism of the compound, would they be more efficacious? A trio of biotech companies has been banking on this prospect for the last decade, and their efforts are starting to trickle into the clinic.