Meet the drug developer taking on wildlife diseases

Chemist Tim Cernak has a wild to-do list: Cure sea turtle cancer. Save frogs from fungal diseases. Take on avian flu.

Speaker names marked ? are inferred from speaking time and the show’s known hosts — they are not voice-verified.

• 0:00Ira Flatow?

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• 0:17Flora Lichtman?

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• 1:03Flora Lichtman?

  There are a lot of drivers of extinction: habitat destruction, pollution, climate change, invasive species. But a consequence of almost all these giant problems is the spread of disease. Right under our noses, many plant and animal species are facing their own little pandemics. Is there something chemists could do to help? My next guest thinks so. Dr. Tim Sernak is a chemist at the University of Michigan. He's been developing drugs for people for 20 years, but more recently, his patient roster has started to include sea turtles, and frogs, and giant reptiles. We'll hear why he's making drugs for wildlife, and why he thinks more chemists should get in on this. Tim, welcome to Science Friday.

• 1:45Speaker 02

  Thanks, Flora.

• 1:46Flora Lichtman?

  It sounds like you're a man on a mission. Can you sum up the mission?

• 1:50Speaker 02

  Yeah, can we, can we use chemistry to improve ecosystem health? I've had the luxury, I guess, of working in human health for so long. And the science is so much fun, right? You're looking at atoms and bonds and you're like buried inside the active side of a protein, imagining a chemical.

• 2:13Flora Lichtman?

  Spoken like a true chemist.

• 2:16Speaker 02

  It was important to me to get quickly to atoms and bonds in this podcast. Cause you know, for all my chemists out there, you know, we just, we just love to draw chemical structures, right? I could be at the chalkboard drawing hexagons all day long. I love it. But you know, just looking around at ecosystems and seeing what's going on in the planet right now, it was hard to just continually look away. And then as soon as you, you know, you start to learn about wildlife diseases and, and that the, the patient populations in some instances are like the last glimmer of their species, like there are, there are animals that there are just a couple hundred of left on this planet. And what's driving their extinction is disease.

• 2:59Speaker 02

  Tasmanian devils are about to go out because of cancer. It's crazy, you know? I mean, Tasmanian devil, remember from like Looney Tunes, the guy's like spinning around and, and that that species is like on the brink of extinction right now because of cancer. It's crazy. So, so it just seems like.

• 3:14Flora Lichtman?

  And you were like, I can do something about this.

• 3:15Speaker 02

  Yeah, yeah, I hope so. In large part, these diseases are ones that we understand really well. You know, cancer, for example, or infectious diseases. And you know, there are some cancers that we can, we can make medicines for quite quickly today. I mean, COVID hit, right? And, and 18 months later, we had a drug. So I think that these technologies that have been bubbling up for drug discovery, of course, AI, you know, has accelerated things, got me thinking like, well, what if, what if there was disease in a turtle or a tree or a butterfly? Like, could we, could we do anything about that situation? Could we prevent the extinction of this creature?

• 4:01Flora Lichtman?

  So I want to talk about where you think you could have the biggest impact. Do you have a white whale of wildlife diseases?

• 4:10Speaker 02

  So the one that we spend a lot of attention on is chytrid. This is a fungal disease that's driving the extinction of frogs across the globe. It's a global event. It's been described by many as the biggest pandemic on our planet. But it's not known to impact mammals in any way, so you hear less about it. But you can kill this fungus with some of our broad spectrum antifungal agents. The problem that I have is that the dosing window is really narrow for those broad spectrum agents. And so there's plenty of studies that show that frogs have been overdosed to death with this old school antifungal.

• 4:55Speaker 02

  The other challenge is that it's an immunosuppressant. And so you treat the frogs, but then there's a hypothesis that when they get back out into the wild after having been treated with this drug, they are more susceptible to the disease. So as someone with a background in pharmacy, I'm like, well, could we find a different option here that doesn't have these design flaws? Because it was never designed for frogs. Could we put something together that really had frogs in mind as the patient in the beginning and maybe come up with a better option for them that's less toxic and easier to apply? And then in terms of how do you apply it? So the way that this happens typically in local environments, the frogs will be collected,

• 5:40Speaker 02

  put in a bath outside of the pond and then re-released into the pond. Or oftentimes, a zoo will have a conservation mission where they are involved in captive breeding of some of the most endangered frogs on the planet. And then they're engaged in reintroducing them to their native environments where they haven't been seen in a long time. And then oftentimes, they're trying to manage this fungal disease while they're doing that work.

• 6:06Flora Lichtman?

  I heard about your patient Pebbles. Tell me more.

• 6:10Speaker 02

  Oh, Pebbles. Yeah, Pebbles is like a mascot for our lab. She's incredible. So she's a Gila monster. She's housed at the Creature Conservancy, which is a wildlife rescue center here in Ann Arbor, Michigan. And you know, the saliva of the Gila monster is where we got these modern weight loss drugs. I'm anticipating that.

• 6:32Flora Lichtman?

  The GLP-1s.

• 6:32Speaker 02

  Yeah, the GLP-1s, right? So the first GLP, like, you know, now we're on like Generation 4 of these medicines that's coming out. But Gen 1 was straight up Gila monster spit, or the one, a single peptide that comes from Gila monster spit. So crazy, right? That like, okay, like, here's this creature.

• 6:50Flora Lichtman?

  Here's a giant reptile just spit in a tube and yeah, a medicine comes out. Yeah.

• 6:56Speaker 02

  And treat diabetes, right? I mean, initially diabetes and then, and then, and we learned about the weight loss aspect of it. I mean, you know, you, maybe you could have predicted this, maybe. Uh, Gila monsters hardly eat, like, they can survive by eating four meals a year. Uh, and, uh, yeah. So, so like, if you had have known that, you could be like, oh, I bet we could make a weight loss drug off of their spit.

• 7:21Speaker 02

  But it turns out there's like a type of scientist that just goes out into the wild and like, decided that they would screen Gila monster spit against diabetes. Like, wow, this works really, really well. So anyway, so Pebbles, back to Pebbles, the Gila monster, um, is a local Gila monster here in Ann Arbor that was infected with a parasite and was slated for euthanasia. And so they're like, we, you know, there's no treatment for this, for this, uh, this disease. You, you can't even kill this parasite with bleach? Like, you have to, the only, the only known way to kill the parasite before we got engaged was boiling it in water, um, which is not a good medicine.

• 7:57Speaker 02

  And, um, we, yeah, we hopped in and, uh, we used our, our, our drug hunting hats, uh, and, and found, um, we, we found a treatment for, for Pebbles and, uh, we worked with the Creature Conservancy. They, they formulated it up. We were really nervous. Remember I said that Gila monsters hardly eat anything? The planned dose was, uh, was seven doses of a pill called Peromomycin over 14 days. We're like, how are we gonna get her to eat? Um, over, over 14 days. I mean, it's, they, they tried the first two doses in little, little pinky mice. So, um, and then she didn't like the mice, but then they formulated it in baby quail.

• 8:40Flora Lichtman?

  Wow.

• 8:41Speaker 02

  I'm sorry, listeners. Um, but anyways, they-

• 8:43Flora Lichtman?

  Wait, did Pebbles survive? Did you cure her?

• 8:47Speaker 02

  Pebbles has been in full remission for a year now. Uh, she regained all the weight she lost and has really beautiful colors now. Uh, and yeah, she's good.

• 8:57Flora Lichtman?

  Besides Pebbles, can you give me one more example of, um, wildlife where you have intervened?

• 9:04Speaker 02

  Sure. So, I mean, avian flu is, is a major, uh, area of research for us. We're identifying those mutant strains of avian flu that are, that are wiping out wildlife populations and trying to design drugs specifically tailored to that situation. Um, sea turtles are an area of, of much excitement for us. We are screening, uh, cancer drugs and, and even attempting to develop new ones that, uh, that would be specifically designed for sea turtles. Because, you know, this is a major disease driving sea turtle stranding in the U.S. right now. They get tumors all over their body and they, they just can no longer, they get so many of

• 9:47Speaker 02

  them that they can't swim. It, it tends to go over their mouth and eyes. It's, it's, it's a really gross disease.

• 9:53Flora Lichtman?

  How do you give a sea turtle a cancer drug?

• 9:56Speaker 02

  Well, sea turtles are one of the iconic species that have sea turtle hospitals. And so we partner with those bodies, uh, that have, uh, you know, pretty, pretty nice equipment for treating sea turtles. But, um, sea turtles don't have much of a blood brain barrier. So for so much of my career, I've been like, how could I get a molecule across the blood brain barrier?

• 10:18Flora Lichtman?

  Right.

• 10:18Speaker 02

  Get a molecule across the blood brain barrier. You enter sea turtles and it's like, oh, we gotta worry about brain toxicity.

• 10:24Flora Lichtman?

  Right. I mean, that, that brings up what must be a big challenge of this work, that animals have different physiology than we do.

• 10:31Speaker 02

  Yes, it is. It definitely is. Yes, it is. Uh, but- But it's, I kind of, I love the way that it flexes our thinking. Like, the cancer that we're looking at in sea turtles, we've noticed a couple pathways that are upregulated in it, that are prevalent in human cancers, but no one's really looked at them. And so, yeah, absolutely. I mean, the biology is alien in some ways. Like, I talked about sea turtles don't have a blood-brain barrier, but it still is, the principles that we learn from this research directly apply to human medicine.

• 11:08Flora Lichtman?

  Yeah, and I guess, you know, the pharmaceutical industry, as you say, with gila monsters, has gotten a lot out of animals.

• 11:15Speaker 02

  Yeah, I mean, there's definitely a giving back component here, right? I mean, also, like, you know, some of the poisonous frogs that we've been looking at are the progenitors of our latest pain medicines that, you know, we've had, there's a new non-opioid pain medicine that's just come out that we really couldn't understand how that new medicine would have worked without some understanding of the poisons that were coming from frogs. I mean, it's just so clear, the natural world has given us so many of our medicines. How could we look away from nature when she's, you know, not feeling so well today?

• 11:56Flora Lichtman?

  Dr. Tim Cernak is an associate professor of medicinal chemistry at the University of Michigan. Tim, thank you so much for joining me.

• 12:02Speaker 02

  It's been my great pleasure, Flora. Thank you.

• 12:05Flora Lichtman?

  This episode was produced by Rasha Aridi, and if we can be the cure to your burning questions, give us a ring. 8774 sci-fry is our number, and you can also rate and review us right here in the very app that you're listening on right now. Catch you next time. I'm Flora Lichtman.