A new type of medicine, custom-made with tiny proteins | Christopher Bahl

I'm a protein designer. And I'd like to discuss a new type of medicine. It's made from a molecule called a constrained peptide. There are only a few constrained peptide drugs available today, but there are a lot that will hit the market in the coming decade. Let's explore what these new medicines are made of, how they're different and what's causing this incoming tidal wave of new and exciting medicines. Constrained peptides are very small proteins. They've got extra chemical bonds that constrain the shape of the molecule, and this makes them incredibly stable as well as highly potent. They're naturally occurring, our bodies actually produce a few of these that help us to combat bacterial, fungal and viral infections. And animals like snakes and scorpions use constrained peptides in their venom. Drugs that are made of protein are called biologic drugs. So this includes constrained peptides, as well as medicines like insulin or antibody drugs like Humira or Enbrel. And in general, biologics are great, because they avoid several ways that drugs can cause side effects. First, protein. It's a totally natural, nontoxic material in our bodies. Our cells produce tens of thousands of different proteins, and basically, all of our food has protein in it. And second, sometimes drugs interact with molecules in your body that you don't want them to. Compared to small molecule drugs, and by this I mean regular drugs, like aspirin, biologics are quite large.

Molecules interact when they adopt shapes that fit together perfectly. Much like a lock and key. Well, a larger key has more grooves

so it's more likely to fit into a single lock. But most biologics also have a flaw. They're fragile. So they're usually administered by injection, because our stomach acid would destroy the medicine if we tried to swallow it. Constrained peptides are the opposite. They're really durable, like regular drugs. So it's possible to administer them using pills, inhalers, ointments. This is what makes constrained peptides so desirable for drug development. They combine some of the best features of small-molecule and biologic drugs into one. But unfortunately, it's incredibly difficult to reengineer the constrained peptides that we find in nature to become new drugs. So this is where I come in. Creating a new drug is a lot like crafting a key to fit a particular lock. We need to get the shape just right. But if we change the shape of a constrained peptide by too much

those extra chemical bonds are unable to form and the whole molecule falls apart. So we needed to figure out how to gain control over their shape. I was part of a collaborative scientific effort that spanned a dozen institutions across three continents that came together and solved this problem. We took a radically different approach from previous efforts. Instead of making changes to the constrained peptides that we find in nature, we figured out how to build new ones totally from scratch. To help us do this, we developed freely available open-source peptide-design software that anyone can use to do this, too. To test our method out, we generated a series of constrained peptides that have a wide variety of different shapes. Many of these had never been seen in nature before. Then we went into the laboratory and produced these peptides. Next, we determined their molecular structures, using experiments. When we compared our designed models

with the real molecular structures, we found that our software can position individual atoms

with an accuracy that's at the limit of what's possible to measure. Three years ago, this couldn't be done. But today, we have the ability to create designer peptides with shapes that are custom-tailored for drug development. So where is this technology taking us? Well, recently, my colleagues and I designed constrained peptides that neutralize influenza virus, protect against botulism poisoning and block cancer cells from growing. Some of these new drugs have been tested in preclinical trials with laboratory animals. And so far, they're all safe and highly effective. Constrained peptide design is a cutting-edge technology, and the drug development pipeline is slow and cautious. So we're still three to five years out from human trials. But during that time, more constrained peptide drugs are going to be entering the drug development pipeline. And ultimately, I believe that designed peptide drugs are going to enable us all to break free from the constraints of our diseases. Thank you. (Applause)