Exploring the Impact of GLP-1 Drugs on Weight Loss and Brain Function

Note: This podcast is a companion to the Ground Truths newsletter “A Big Week for GLP-1 Drugs”

Eric Topol (00:06):

It is Eric Topol with Ground Truths, and with me today is Dr. Daniel Drucker from the University of Toronto, who is one of the leading endocrinologists in the world, and he along with Joel Habener and Jens Juul Holst from the University of Copenhagen and Denmark, have been credited with numerous prizes of their discovery work of glucagon-like peptide-1 (GLP-1) as we get to know these family of drugs and he's a true pioneer. He's been working on this for decades. So welcome, Daniel.

Daniel Drucker (00:43):

Thank you.

Eric Topol (00:45):

Yeah, it's great to have you and to get the perspective, one of the true pioneers in this field, because to say it's blossom would be an understatement, don't you think?

Daniel Drucker (00:57):

Yeah, it's been a bit of a hectic three years. We had a good quiet 30 plus years of solid science and then it's just exploded over the last few years.

Eric Topol (01:06):

Yeah, back in 30 years ago, did you have any sense that this was coming?

Daniel Drucker (01:14):

Not what we're experiencing today, I think there was a vision for the diabetes story. The first experiments were demonstrating insulin secretion and patents were followed around the use for the treatment of GLP-1 for diabetes. The food intake story was much more gradual and the weight loss story was quite slow. And in fact, as you know, we've had a GLP-1 drug approved for people with obesity since 2014, so it's 10 years since liraglutide was approved, but it didn't really catch the public's attention. The weight loss was good, but it wasn't as spectacular as what we're seeing today. So this really has taken off just over the last three, four years.

Eric Topol (01:58):

Yeah, no, it's actually, I've never seen a drug class like this in my life, Daniel. I mean, I've obviously witnessed the statins, but this one in terms of pleiotropy of having diverse effects, and I want to get to the brain here in just a minute because that seems to be quite a big factor. But one thing just before we get too deep into this, I think you have been great to recognize one of your colleagues who you work with at Harvard, Svetlana Mojsov. And the question I guess is over the years, as you said, there was a real kind of incremental path and I guess was in 1996 when you said, well, this drug likely will inhibit food intake, but then there were gaps of many years since then, as you mentioned about getting into the obesity side. Was that because there wasn't much weight loss in the people with diabetes or was it related to the dose of the drugs that were being tested?

Why Did It Take So Long to Get to Obesity?

Daniel Drucker (03:11):

Well, really both. So the initial doses we tested for type 2 diabetes did not produce a lot of weight loss, maybe 2-3%. And then when we got semaglutide for type 2 diabetes, maybe we were getting 4-5% mean weight loss. And so that was really good and that was much better than we achieved before with any glucose lowering drug. But a lot of credit goes to Novo Nordisk because they looked at the dose for liraglutide and diabetes, which was 1.8 milligrams once daily for people with type 2 diabetes. And they asked a simple question, what if we increase the dose for weight loss? And the answer was, we get better weight loss with 3 milligrams once a day. So they learn that. And when they introduced semaglutide for type 2 diabetes, the doses were 0.5 and 1 milligrams. But in the back of their minds was the same question, what if we increased the dose and they landed on 2.4 milligrams once a week. And that's when we really started to see that the unexpected spectacular weight loss that we're now quite familiar with.

Eric Topol (04:16):

Was there also something too that diabetics don't lose as much weight if you were to have match dose?

Daniel Drucker (04:22):

Yeah, that's a general phenomenon. If one goes from either diet to bariatric surgery, and certainly with weight loss medicines, we tend to see maybe two thirds to three quarters of the amount of weight loss in people with type 2 diabetes. We don't really understand it. The brain pathways are probably resistant to some of the pathways that are activated that lead to weight loss, and it's really an interesting observation that needs further study.

The Brain Effect

Eric Topol (04:50):

Yeah, it's fascinating really. And it might've at least in part, held up this progress that has been truly remarkable. Now, recently you published a paper among many, you're a very prolific scientist, of course, physician scientist, but back in December in Cell Metabolism was a very important paper that explored the brain gut axis, the ability to inhibit inflammation and the mechanism through Toll-like receptors that you were seeing that. So maybe you could summarize the fact that you saw this, you were quoted in this Atlantic piece by Sarah Zhang, the science behind Ozempic was wrong. The weight loss effects of GLP-1 drugs have little to do with the gut and basically claiming that it's related to the effects on the brain, which of course could be reduced inflammation, reduced or inhibiting centers of addiction craving, that sort of thing. So how do you interpret your recent results and ongoing studies regarding GLP-1's effect on the brain?

Daniel Drucker (06:02):

Sure, so to be clear, I don't think that was a quote. I never would've said the science behind Ozempic was wrong. I think that was a headline writer doing what they do best, which is catching people's attention. I think what I was trying to say is that where this field started with insulin secretion first and then weight loss second, those are clearly very important pharmacological attributes of GLP-1. But physiologically, if we take GLP-1 away or we take the receptor away, you don't really develop diabetes without GLP-1. You don't really gain a lot of weight without GLP-1. So physiologically it's not that important. Why do we have GLP-1 in the distal gut? I think physiologically it's there to defend against infection and reduce gut inflammation. But we noticed that GLP-1 reduces inflammation in many different places in the heart and blood vessels and in the liver and many organs where you don't see a lot of GLP-1 receptors and you don't see a lot of GLP-1 receptors on immune cells.

Daniel Drucker (07:04):

So that really led us to the question, well, how does it work and affect all these organs where we don't see a lot of the receptors? And that's where we landed on the brain. Obviously the nervous system can communicate with many different cell types in almost every organ. And we identified neurons that expressed the GLP-1 receptor, which when blocked abrogated or completely eliminated the ability of GLP-1 to reduce inflammation in the periphery in white cells or in lungs. So it's been known for some time that the brain can control the immune system. So this is just the latest piece in the puzzle of how GLP-1 might reduce inflammation.

Eric Topol (07:49):

And just to be clear, I was quoting the Atlantic headline, not you that you were quoted within that article, but this is something that's really interesting because obviously GLP-1 is made in the brain in certain parts of the brain, it's transient in terms of its half-life made from the gut. But when we give these drugs, these agonists, how does it get in the brain? Because isn't there a problem with the blood brain barrier?

Daniel Drucker (08:22):

So I don't think the drugs get into the brain very well. We have a lot of data on this, so people have done the classic experiments, they either make radioactive ligands or fluorescent ligands, and they look how much gets in it and not very much gets in beyond the blood-brain barrier. And we also have big drugs that are immunoglobulin based and they work really well, so they don't get into the brain very much at all. And so, the way I describe this is that GLP-1 talks to the brain, but it doesn't directly get into the brain to meaningful extent, it does communicate somewhat there are areas obviously that are accessible in the area of the stream and circumventricular organs, but most of the time we have this communication that's not well understood that results in the magic that we see. And there are some discussions around for the neurodegenerative disease story where GLP-1 is being looked at in Parkinson's disease and in people with Alzheimer's disease. Would you be able to get more benefit if you could get the drugs into the brain to a greater extent, or would you simply increase the adverse event profile and the adverse response? So really important area for study as we begin to go beyond diabetes and obesity.

Eric Topol (09:41):

Yeah, I mean as you're pointing out, there's two ongoing trials, pretty large trials in Alzheimer's, early Alzheimer's, which may be a little bit too late, but at any rate, testing GLP-1 to see whether or not it could help prevent progression of the disease. And as you also mentioned, diseases and Parkinson's. But I guess, so the magic as you referred to it, the gut -brain axis so that when you give the GLP-1 family of drugs, we'll talk more about the double and triple receptor in a moment, but when you give these drugs, how does the message you get from the gut to the brain would you say?

Daniel Drucker (10:27):

So pharmacologically, we can give someone or an animal the drug, it does reach some of the accessible neurons that have GLP-1 receptors, and they probably transmit signals deeper into the brain and then activate signal transduction. So one way to look at it, if you use c-fos, the protein, which is an immediate early gene, which is increased when we activate neurons, we see rapid activation of c-fos in many regions that are deep within the brain within minutes. And we know that GLP-1 is not getting directly to those neurons, but it's activating pathways that turn on those neurons. And so, there's probably a very intricate set of pathways that sense the GLP-1 and the accessible neurons and then transmit those signals deeper into the brain.

Double and Triple Receptor Agonists

Eric Topol (11:18):

Okay, well that makes sense. Now, as this has been moving along in obesity from semaglutide to tirzepatide and beyond, we're seeing even more potency it appears, and we have now double and triple receptors adding into glucagon itself and the gastric inhibitory polypeptide, and there's mixed data. So for example, the Amgen drug has the opposite effect on GIP as does the dual receptor, but comes out with the same weight loss I guess. How do we understand, I mean you know these gut hormones inside and out, how do we get such disparate results when you're either blocking or revving up a peptide effect?

Daniel Drucker (12:13):

Yeah, it's a mystery. I always sort of joke that you've invited the wrong person because I don't fully understand how to reconcile this honestly. There are some theories you could say that tirzepatide may possibly desensitize the GIP receptor, and that would align with what the GIP receptor blocking component is. And so, I think we need a lot of research, we may actually never know in humans how to reconcile these observations. I think we can do the experiments in animals, we're doing them, other people are doing them to look at the gain and loss of function and use best genetics. But in humans, you'd have to block or activate these receptors in very specific populations for a long period of time with tools that we probably don't have. So we may not reconstruct. We may end up with Maritide from Amgen that's producing 15-20% plus weight loss and tirzepatide from Lilly, that's spectacular, that's producing more than 20% weight loss. And yet as you mentioned at the GIP level, they have opposite effect. So I don't think we fully understand. Maybe your next guest will explain it to you and invite me on. I'd be happy to listen.

Eric Topol (13:27):

Well, I don't know. I don't think anybody can explain it. You've done it as well as I think as possible right now. But then we have the triple receptor, which it seems like if you take that drug, you could just go kind of skeletal. It seems like there's no plateau and its effect, that is I guess is it retatrutide, is that the name of it?

Daniel Drucker (13:47):

Retatrutide, yeah.

Eric Topol (13:48):

Retatrutide, okay. And then of course we're going on with potentially oral drugs or drugs that last for a year. And where do you see all that headed?

Daniel Drucker (14:00):

So I think the way I describe innovation in this field is there are two buckets that we've talked about today. So one bucket is the new molecule, so we're going to have all kinds of different combinations that will be peptides, that will be small molecule orals, the NIH is funding innovative programs to see if we can develop cell-based factories that produce GLP-1. There are gene editing and gene therapy approaches. So there are going to be multiple different molecular approaches to delivering molecules that are better and hopefully easier to take maybe once monthly, maybe every six months. So that's really exciting. And the other obvious bucket is the disease that we're targeting, so we started off with type 2 diabetes. We're now firmly established in the obesity field. In your field, we've seen consistently positive cardiovascular outcome trials. We had a press release a few months ago in October - November saying that semaglutide reduces chronic kidney disease. We have trials underway with peripheral artery disease with Parkinson's disease, with Alzheimer's and a number of neuropsychiatric conditions. So I think we're going to see both innovation on the molecule side as well as expanding if the trials are positive, expanding clinical indication. So it's going to be a pretty exciting next couple of years.

Eric Topol (15:21):

Right, no question. And as you well know, just in the past week, the FDA gave the green light for using these drugs for heart failure with preserved ejection fraction, which was an important randomized trial that showed that. Now there's got to be some downsides of course there's no drug that's perfect. And I wanted to get your comments about muscle loss, potentially bone density reduction. What are the downsides that we should be thinking about with these drugs?

Side Effects

Daniel Drucker (15:54):

Sure, so the known side effects are predominantly gastrointestinal. So we have nausea, diarrhea, constipation and vomiting. And very importantly, if those side effects are severe enough that someone can't eat and drink for 24 hours, we need to tell them you have to seek medical attention because some people will get dehydrated and rarely get acute kidney injury. This is rare, but it's described in many of the outcome trials, and we definitely want to avoid that. Gallbladder events are probably one in several hundred to one in a thousand, and that can be anywhere from gallbladder inflammation to gallbladder stones to biliary obstruction. Don't fully understand that although GLP-1 does reduce gallbladder motility, so that may contribute. And then very rarely we're seeing reports of small bowel obstruction in some people difficult to sort out. We don't really see that in the large clinical trials, but we have to take people at there were, we haven't seen an imbalance in pancreatitis, we haven't seen an imbalance of cancer.

Daniel Drucker (17:01):

There is no evidence for clinically significant bone disease either at the level of reduced bone densities or more importantly at the level of fractures. And we have a lot of real world data that's looked at that. Now muscle losses is really interesting. So when the initial drugs were approved, they didn't produce much weight loss. We didn't think about it. Now that we're getting the 15 20% plus, the question is, will we see clinically significant sarcopenia? And I use the word clinically significant carefully. So we definitely see muscle lean mass loss on a DEXA scan, for example. But what we're not seeing so far are people who are saying, you know what my grip strength is weak. I can't get up off the chair. I have trouble reaching up into the cupboard. My exercise or walking capacity is limited. We’re not seeing that. In fact, we’re seeing the opposite.

Daniel Drucker (17:53):

As you might expect, people are losing weight, they’re less achy, they can move more, they can exercise more. So the question is buried within that data, are there some individuals with real clinical sarcopenia? And as we get to 25% weight loss, it’s very reasonable to expect that maybe we will see some individuals with clinical sarcopenia. So you’re very familiar. There are half a dozen companies developing medicines to promote fat mass loss and spare muscle with or without semaglutide or tirzepatide. And this is a really interesting area to follow, and I don’t know how it’s going to turn out. We really have to see if we are going to see enough clinically significant muscle loss and sarcopenia to merit a new drug category emerge, so fascinating to follow us.

Eric Topol (18:46):

No, I’m so glad you reviewed that because the muscle loss, it could be heterogeneous and there could be some people that really have some substantial sarcopenia. We’ll learn more about that. Now that gets me to what do we do with lifelong therapy here, Daniel, where are we going? Because it seems as though when you stop these drugs, much of the benefit can be not potentially all, but a substantial amount could be lost over time. Is this something that you would view as an insulin and other hormonal treatments or how do you see it?

The Question of Rebound

Daniel Drucker (19:26):

Yeah, so it’s fascinating. I think that traditional view is the one that you just espoused. That is you stop the drug, you regain the weight, and people are concerned about the rebound weight and maybe gaining more fat and having less favorable body composition. But if you look at the data, and it’s coming very fast and furious. A few months ago, we saw data for a tirzepatide trial, one of the surmount obesity trials, the first author was Louis Aronne in New York and they gave people tirzepatide or placebo for 38 weeks. And then they either continue the tirzepatide or stop the tirzepatide. One year later, so no tirzepatide for one year, more than 40% of the people still managed to keep at least 10% of their weight off, which is more than enough in many people to bestow considerable metabolic health. So I think there are going to be people that don't need to take the medicines all the time for weight loss, but we must remember that when we're excited about heart attacks and strokes and chronic kidney disease, there's no evidence that you can stop the medicines and still get the benefits to reduce those chronic complications.

Daniel Drucker (20:46):

So we're going to have to get much more sophisticated in terms of a personalized and precision medicine approach and ask what are the goals? And if the goals are to reduce heart attack strokes and death, you probably need to stay on the medicine if the goals are to achieve weight loss so that you can be metabolically healthy, there may be a lot of people who can come off the medicine for considerable amounts of time. So we're just learning about this. It's very new and it's really exciting.

Suppressing Inflammation as the Common Thread

Eric Topol (21:11):

Yeah, no question. And just going back to the inflammation story in heart disease, it was notable that there were biomarkers of reduced inflammation in the intervention trial before there was any evidence of weight loss. So the anti-inflammatory effects here seem to be quite important, especially with various end organ benefits. Would you say that's true?

Daniel Drucker (21:35):

Yeah, I think that's one of my favorite sort of unifying theories. If we step back for a minute and we come into this and we say, well, here's a drug that improves heart disease and improves liver inflammation and reduces chronic kidney disease and may have some effect on atherosclerosis and is being studied with promising results and neurodegenerative disease, how do we unify all that? And one way is to say all of these chronic disorders are characterized by a component of chronic inflammation. And Eric, it's fascinating. I get reports from random strangers, people who've been on tirzepatide or people who have been on semaglutide, and they tell me, and you'll be fascinated with this, they tell me, my post Covid brain fog is better since I started the drug. They send me pictures of their hands. These are people with chronic arthritis. And they say, my hands have never looked better since I started the drug. And they tell me they've had ulcerative colitis for years on biologics and all of a sudden it's in remission on these drugs. So these are case reports, they're anecdotes, but they're fascinating and quite consistent with the fact that some people may be experiencing an anti-inflammatory effect of these medicines.

Eric Topol (22:55):

And I think it's notable that this is a much more potent anti-inflammatory effect than we saw from statins. I mean, as you know, well they have an effect, but it's not in the same league, I don't think. And also the point you made regarding this is a very good candidate drug class for Long Covid and for a variety of conditions characterized by chronic inflammation. In fact, so many of our chronic diseases fit into that category. Well, this is fascinating, and by the way, I don't know if you know this, but we were both at Johns Hopkins at the same time when you were there in the early eighties. I was there as a cardiology fellow, but we never had a chance to meet back then.

Daniel Drucker (23:41):

So were you just ahead of Cricket Seidman and the whole team there, or what year was that?

Eric Topol (23:46):

Just before them, that's right. You were there doing, was it your internship?

Daniel Drucker (23:50):

I was doing an Osler internship. I think Victor McKusick loved to have a Canadian every year to recognize Osler, one of the great Canadians, and I was just lucky to get the slot that year.

Eric Topol (24:04):

Yeah, it's wild to have watched your efforts, your career and your colleagues and how much of a profound impact. If you were to look back though, and you were to put this into perspective because there were obviously many other hormones along the way, like leptin and so many others that were candidates to achieve what this has. Do you think there's serendipity that play out here or how do you kind of factor it all together?

Daniel Drucker (24:38):

Well, there there's always serendipity. I mean, for decades when people would write review articles on the neuropeptides that were important for control of hunger and satiety and appetite circuits, I would open the article, read it, and I'd say, darn, there's no GLP-1 on the figure. There's no GLP-1 or receptor on the figure, but there's leptin and agouti and the POMC peptides and all the melanocortin and so on and so forth, because physiologically, these systems are not important. As I mentioned, you don't see childhood obesity or genetic forms of obesity in people with loss of function mutations in the GLP-1 sequence or in the GLP-1 receptor. You just don't see a physiologically important effect for having low GLP-1 or having no GLP-1. And that's of course not the case for mutations in NPY or the melanocortin or leptin, et cetera.

Other Effects

Daniel Drucker (25:36):

But pharmacologically, it's been extraordinarily difficult to make drugs out of these other peptides and pathways that we talked about. But fortuitously or serendipitously, as you point out, these drugs seem to work and amazingly GPCRs are notoriously prone to desensitization. We use that in clinical medicine to turn off entire circuits. And thankfully what goes away with GLP-1 are the adverse effects. So nausea, vomiting, diarrhea, constipation, we see those during the first few weeks and then there’s tachyphylaxis, and they generally go away in most people, but what doesn't go away through good fortune are the ability of GLP-1 to talk to those brain circuits and say, you know what? You're not hungry. You don't need to eat. You don't need to think about food. And that's just good luck. Obviously pharmacologically that's benefited all of us working in this area.

Eric Topol (26:31):

It's extraordinary to be able to get desensitized on the adverse effects and not lose the power of the benefit. What about addiction that is, whether it's alcohol, cigarettes, gambling, addictive behavior, do you see that that's ultimately going to be one of the principal uses of these drugs over time?

Daniel Drucker (26:55):

The liver docs, when I give a talk at a metabolic liver disease meeting, they say we love GLP-1 because not only might it take care of liver disease, but there are still some people that we see that are having problems with alcohol use disorders and it might also reduce that. And obviously there are tons of anecdotes that we see. If you go on social media, and you'll see lots of discussion about this, and there's a hundred or so animal paper showing that addiction related dependence behaviors are improved in the context of these medicines. But we don't have the clinical data. So we have a couple of randomized clinical trials, small ones in people with alcohol use disorder, very unimpressive data. We had a trial in people with smoking, didn't really see much, although interestingly, they noted that people drank less alcohol than they did the smoking trial. So there are dozens and dozens of trials underway now, many investigator initiated trials looking at whether it's nicotine or cocaine or cannabinoids or all kinds of compulsive behaviors. I think in the next 12 to 24 months, we're going to start to learn are these real bonafide effects that are seen in large numbers of people or are these just the anecdotes that we won't get a very good complete response. So it's really exciting neuroscience and we're going to learn a lot over the next couple of years.

Eric Topol (28:20):

Yeah, no, it's a fascinating area which just extends the things that we've been discussing. Now, let's say over time, over the years ahead that these drugs become because of the competition and various factors, perhaps in pill form or infrequent dosing, they become very inexpensive, not like they are today.

Daniel Drucker (28:44):

That'd be great speaking as a non-pharmaceutical physician.

Eric Topol (28:48):

Yeah, yeah, no, these companies, which of course as you well know, it accounts for the number one economy in Denmark and is having a big impact in Europe. And obviously Eli Lilly is now the most valued biopharma company in the world from all these effects are coming from this drug class, but let's just say eventually it's not expensive and the drug companies are not gouging and pleasing their investors, and we're in a different world. With all these things that we've been discussing, do you foresee a future where most people will be taking one form or another of this family of drugs to prevent all these chronic conditions that we've just been discussing independent of obesity, type 2 diabetes, the initial frontier? Do you think that's possible?

Daniel Drucker (29:42):

Yeah, I'm a very conservative data-driven person. So today we don't have the data. So if I was in charge of the drinking water supply in your neighborhood and I had unlimited free cheap GLP-1, I wouldn't dump it in there just yet. I don't think we have the data, but we have trials underway, as you noted for Alzheimer's disease, a challenging condition for our society with a huge unmet need if like fingers crossed, if semaglutide does show a benefit for people living with early Alzheimer's disease, if it helps for Parkinson's, if it helps for metabolic liver disease, there are also studies looking at aging, et cetera. So it's possible one day if we have a lot more data that we will begin to think, okay, maybe this is actually a useful medicine that should deserve much more exposure, but today we just don't have the data.

Eric Topol (30:38):

Absolutely. I couldn't agree more, but just wanted to get you kind of speculate on that a bit off script if you will, but what your thoughts were, because this will take a long time, get to that point, but you just kind of wonder when you have an absence of chronic significant side effects overall with these diverse and relatively potent benefits that cut across many organ systems and as you just mentioned, might even influence the aging process, the biologic process.

Worsening Inequities

Daniel Drucker (31:10):

There's another related sort of angle to this, which is that the accessibility of these medicines is very challenging even in well-developed countries, the United States, Europe, et cetera, and we have hundreds of millions of people in the global south and less well-developed economies that are also challenged by heart disease and diabetes and obesity and chronic kidney disease and liver disease. And I think we need to start having conversations and I think they are happening just like we did for HIV and just like we did for hepatitis and certainly we did very quickly for the Covid vaccines. We need to think out of the box and say we need to help people in other parts of the world who may not have access to the medicines in their current form and at their current pricing. And I think these are really important moral and ethical discussions that need to be happening now because soon we will have small molecules and the price will come down and we need to make sure it's not just people in well-developed countries that can afford access to these medicines. I think this is a great opportunity for pharmaceutical companies and the World Health Organization and other foundations to really think broadly about how we can benefit many more people.

Eric Topol (32:29):

I couldn't agree with you more and I'm so glad you emphasize that because we can't wait for these prices to come down and we need creative ways to bridge, to reduce inequities in a vital drug class that's emerged to have far more applicability and benefit than it was initially envisioned, certainly even 5, 10 years ago, no less 30 years ago when you got on it. So Daniel, I can't thank you enough for this discussion. Really a candid discussion reviewing a lot of the things we do know, don't know will know someday perhaps. I just want to note, I know so many people are cheering for you and your colleagues to get recognized further like by the Nobel folks in the years ahead. I think it's pretty darn likely and hopefully when we get a chance to visit again in the years ahead, we'll unravel some of the things that we discussed today that we didn't know the answers and that you as a really an authority and pioneer in the field. Also, I could admit that there's a ways to go to really understand the boundaries if there are boundaries here for how these drugs are going to be used in the years ahead.

Daniel Drucker (33:51):

Yeah, it's another great story for basic science and bench to bedside, and it's just another story where none of us could have predicted the outcomes that we're talking about today to their full extent. And so to the extent that we can convince our governments and our funding agencies to really fund discovery science, the benefits are never apparent immediately. But boy, do they ever come in spades later on in an unpredictable manner. And this is just a great example.

Eric Topol (34:20):

Yeah, I also would say that this work cracking the case of obesity, which has been a stumbling block, I ran a big trial with Rimonabant, which was a failure with the neuropsychiatric side effects and suicidal ideation that had to get dropped. And there's many others like that as you know, very well Fen-Phen, and a long list. And the fact that this could do what it's doing and well beyond just obesity is just spectacular. And what I think it does, what you just mentioned, Daniel, is the basic science work that led to this is I think an exemplar of why we should put in these efforts and not expect immediate benefits, dividends of those efforts. Because look what's happened here. If you can break through with obesity, imagine what lies ahead. So thanks so much for joining and we'll look forward to continuing to follow your work. I know you're publishing the same pace, exceptional prolific pace over many, many years, and I'm sure that's going to continue.

Daniel Drucker (35:34):

Well, I have a great team and so it's a pleasure me to go into work and talk to them every day.

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