Meet the drug developer taking on wildlife diseases

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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 Cernak 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.

TIM CERNAK: Thanks, Flora.

FLORA LICHTMAN: It sounds like you’re a man on a mission. Can you sum up the mission?

TIM CERNAK: Yeah, 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. You’re looking at atoms and bonds, and you’re buried inside the active site of a protein, imagining a chemical–

FLORA LICHTMAN: Spoken like a true chemist. That’s a chemist idea of fun.

TIM CERNAK: Yeah, yeah, sure. It was important to me to get quickly to atoms and bonds in this podcast because for all my chemists out there, we just love to draw chemical structures. I could be at chalkboard drawing hexagons all day long. I love it.

But 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 start to learn about wildlife diseases and that the patient populations in some instances are the last glimmer of their species, there are animals that are just a couple hundred of left on this planet. And what’s driving their extinction is disease. Tasmanian devils are about to go out because of cancer. It’s crazy.

Tasmanian devil, remember from Looney Tunes, the guy’s spinning around, and that species is like on the brink of extinction right now because of cancer. It’s crazy. So it just seems like–

FLORA LICHTMAN: And you were like I can do something about this.

TIM CERNAK: Yeah, I hope so. In large part, these diseases are ones that we understand really well, cancer, for example, or infectious diseases. And there are some cancers that we can make medicines for quite quickly today. COVID hit, 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 has accelerated things– got me thinking like, well, what if there was disease in a turtle or a tree or a butterfly. Could we do anything about that situation? Could we prevent the extinction of this creature?

FLORA 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?

TIM CERNAK: 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. 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, 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.

FLORA LICHTMAN: I heard about your patient Pebbles. Tell me more.

TIM CERNAK: Oh, Pebbles. Yeah, Pebbles is– 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 the saliva of the gila monster is where we got these modern weight loss drugs. I’m–

FLORA LICHTMAN: The GLP-1s.

TIM CERNAK: Yeah, the GLP-1s. So the first GLP, now we’re on generation four of these medicines that’s coming out. But gen one was straight up gila monster spit or a single peptide that comes from gila monster spit. So crazy that here’s this creature–

FLORA LICHTMAN: Here’s a giant reptile just spit in a tube and, yeah, a medicine comes out. Yeah.

TIM CERNAK: And treat diabetes, initially diabetes, and we learned about the weight loss aspect of it. Maybe you could have predicted this. Maybe. Gila monsters hardly eat. They can survive by eating four meals a year and, yeah. So if you had have known that you could be like, oh, I bet we could make a weight loss drug off of their spit.

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

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

I’m sorry, listeners. But anyways–

FLORA LICHTMAN: Wait, did Pebbles survive? Did you cure her?

TIM CERNAK: Pebbles has been in full remission for a year now. She regained all the weight she lost and has really beautiful colors now. And, yeah, she’s good.

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

TIM CERNAK: Sure. So avian flu is a major area of research for us. We’re identifying those mutant strains of avian flu that are wiping out wildlife populations and trying to design drugs specifically tailored to that situation.

Sea turtles are an area of much excitement for us. We are screening cancer drugs and even attempting to develop new ones that would be specifically designed for sea turtles. Because this is a major disease driving sea turtle stranding in the US right now. They get tumors all over their body, and they just can no longer– they get so many of them that they can’t swim. It tends to go over their mouth and eyes. It’s a really gross disease.

FLORA LICHTMAN: How do you give a sea turtle a cancer drug?

TIM CERNAK: Well, sea turtles are one of the iconic species that have sea turtle hospitals. And so we partner with those bodies that have pretty nice equipment for treating sea turtles. But 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. How could I get a molecule across the blood brain barrier? You enter sea turtles, and it’s like, oh, we got to worry about brain toxicity.

FLORA LICHTMAN: That brings up what must be a big challenge of this work, that animals have different physiology than we do.

TIM CERNAK: Yes, it is. It definitely is. Yes, it is. But it’s– I love the way that it flexes our thinking. The cancer that we’re looking at in sea turtles, we’ve noticed a couple pathways that are up-regulated in it that are prevalent in human cancers but no one’s really looked at them.

And so, yeah, absolutely. The biology is alien in some ways. I talk 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.

FLORA LICHTMAN: Yeah. And I guess the pharmaceutical industry as you say with gila monsters has gotten a lot out of animals.

TIM CERNAK: Yeah, there’s definitely a giving back component here. Also some of the poisonous frogs that we’ve been looking at are the progenitors of our latest pain medicines that– 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. 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 not feeling so well today?

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

TIM CERNAK: It’s been my great pleasure, Flora. Thank you.

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FLORA LICHTMAN: This episode was produced by Rasha Aridi. And if we can be the cure to your burning questions, give us a ring 877-4SCIFRI 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.

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