Macrocyclic peptides: Aiming for the perfect fit

In the search for new drugs, a series of advances in laboratory technologies and computing power has conspired to make the next generation of therapeutic molecules feel tantalizingly within reach. Known as macrocyclic peptides, these drugs are purported to create the Goldilocks effect—they have the size and shape to provide the advantages of both small- and large-molecule drugs without their shortcomings. Small-molecule drugs have been instrumental in alleviating a gamut of ailments, from heart disease to the humble headache, but some experts now think we've exhausted the number of targets those drugs can reasonably tackle. In contrast, large, protein-based drugs can target protein interactions that small molecules have a hard time influencing, but larger molecules have their own drawbacks. That's why scientists have been pursuing macrocyclic peptides. Researchers and investors are betting on building therapeutics from these medium looped molecules. "Macrocyclic peptides provide the best of both worlds," says Vikram