#114 – Eileen White, Ph.D.: Autophagy, fasting, and promising new cancer therapies

1. 0:00 – 3:40

   Intro

   1. PAPeter Attia0:01

      [upbeat music] Hey everyone, welcome to The Drive Podcast. I'm your host, Peter Attia. This podcast, my website, and my weekly newsletter all focus on the goal of translating the science of longevity into something accessible for everyone. Our goal is to provide the best content in health and wellness, full stop, and we've assembled a great team of analysts to make this happen. If you enjoy this podcast, we've created a membership program that brings you far more in-depth content if you want to take your knowledge of this space to the next level. At the end of this episode, I'll explain what those benefits are, or if you want to learn more now, head over to peterattiamd.com/subscribe. Now, without further delay, here's today's episode. [upbeat music] My guest this week is Professor Eileen White. Eileen is the Deputy Director and Chief Scientific Officer, along with the Associate Director for Basic Research and the co-leader of the Cancer Metabolism and Growth Research Program at Rutgers University Cancer Institute in New Jersey. She received her bachelor's degree from RPI and her PhD from SUNY in Stony Brook, and did her postdoc with Bruce Stillman at Cold Spring Harbor Laboratory. Eileen's early work focused on apoptosis, but it was doing some of the work there that she stumbled upon autophagy, and that is the focus of our discussion today. Now, if you're even remotely familiar with this podcast, you'll certainly know that the concept of autophagy has come up on so many previous episodes. It is a fundamental pillar of health and maintenance of health. We talk a lot about it in the context of fasting in particular. I have wanted to sit down with Eileen for a really long time, and I don't think this conversation disappoints, although we certainly could have gone longer. In this discussion, we talk about Eileen's career and how it morphed from studying apoptosis into autophagy. We go into describing the regulation of autophagy, both metabolically and otherwise. And then we spend a lot of time talking about the role autophagy plays in both the prevention of disease and also the treatment of disease. And I think this is where it gets really interesting, especially around cancer. And I think that that's potentially one of the most confusing aspects of the entire discussion on autophagy. And that's actually one of the reasons I really wanted to talk to Eileen, was to better understand something that at the surface seems confusing to me, which is that autophagy seems to very clearly protect a person or an organism from getting cancer. Yet once someone has cancer, it appears that autophagy may disproportionately benefit the cancer cell versus the non-cancer cell. So we tease this idea apart along with talking about the amazing work that her lab has done to demonstrate the importance of autophagy in preventing Alzheimer's disease and neurodegeneration, along with the benefits of metabolic health. And of course, we do talk about the age-old question that many of you have heard me go on and on about, which is how do we delineate and understand the dosing and frequency of fasting as a tool? In other words, when I talk about doing a fast of three days every month versus seven days a quarter versus five days a quarter, how could we possibly get a handle on what the ideal strategy is? And so we talk a lot about that as well, and I'm actually quite hopeful that from this discussion comes, um, some, some research that can shed light on that. So without further delay, I hope you enjoy my discussion on autophagy with Eileen White. [upbeat music]

2. 3:40 – 10:00

   Eileen’s discovery that a specific oncogene blocks apoptosis

   1. PAPeter Attia3:41

      Eileen, thank you so much for extending your trip in San Diego for a day to come and make time to talk with me about this stuff today.

   2. EWEileen White3:48

      Oh, it's my pleasure. I'm looking forward to it.

   3. PAPeter Attia3:50

      I don't know if you remember this, by the way, but David Sabatini introduced us a few years ago. Do you remember when we had this-

   4. EWEileen White3:56

      I do.

   5. PAPeter Attia3:56

      Yeah. I still have my notes from that phone call five years ago. I took about 20-- maybe not 20, that's an exaggeration, maybe 10 pages of notes in my sort of journal, and for, probably have gone back to those a dozen times in the last five or six years. So I always appreciate it when people just pick up the phone and talk to total strangers for no reason. So, uh, that's greatly appreciated.

   6. EWEileen White4:17

      Well, you were excited about the science, and so nerds like me like to talk about science.

   7. PAPeter Attia4:24

      [chuckles] Well, let's actually start from there. Tell me where your interest in science came from. Was it something that was always in you from a young age? Were you just naturally curious?

   8. EWEileen White4:33

      Yeah. I've been asked that question many times before. I come from a family where there was an interest in science. My mother was a elementary school teacher, and my father was a lawyer, but he always wanted to be in science. And all of our discussions were related a lot to new scientific discoveries. So from an early age, I was introduced to science, which was probably unusual. And I then went to college and majored in science and biology and continued from there. And I decided when I was an undergraduate, I wanted to get a PhD in biology, and I was very fortunate to go into graduate school in the department led by Dr. Arnie Levine, who discovered P53. And that was an inspirational experience because he has got scientific insight that's absolutely incredible. And then I went on to Cold Spring Harbor Lab, where I was a postdoc with Bruce Stillman, and again, another incredible scientist, and it was an incredible scientific environment. There were a whole cadre of investigators there that were making major contributions in the field of cancer at the time, and it was just a very thrilling experience to be in an environment where once a week there was some fabulous discovery and everyone was excited about it. There were even, I think, two Nobel Prizes awarded while I was there. And I joined the faculty at Cold Spring Harbor after that, and then I moved on to Rutgers, and I had the fortunate experience of building a cancer center. So when I went to Rutgers to be on the faculty, there was no cancer center, but shortly after I arrived, they hired a cancer center director, uh, Bill Hite from Yale, and I joined him to help build what's now the Rutgers Cancer Center or the Rutgers Cancer Institute, which went from nothing to now there are multiple buildings, there are eleven hospitals in our health system. We have two hundred and forty something members of the Rutgers Cancer Institute, and we have-- We're a consortium cancer center with Princeton University. And so it was very thrilling for me to not only have-- maintain my scientific interest by running a research lab, but also help expand and grow something from nothing, where now we're treating large numbers of patients in, in standard of care and clinical trials and making large discoveries and moving cancer treatment, advancing cancer treatment as fast as we can.

   9. PAPeter Attia7:32

      And how many years have you been at Rutgers?

   10. EWEileen White7:34

       I joined there in nineteen ninety, so I've been there for a long time, but I moved about twelve years ago. I moved from one research building to be physically in the cancer center where I could be more directly helpful.

   11. PAPeter Attia7:50

       So where in your journey did autophagy pique your curiosity?

   12. EWEileen White7:56

       It was purely serendipity. So this goes back to when I was a postdoc with Bruce Stillman at Cold Spring Harbor. I was given an oncogene to study. That time they had just sequenced the adenovirus genome. They knew what genes caused cancer in the virus. I was given one of those genes and said, "Figure out what it does." And that was a dream project for a postdoc. And what I found was that this gene was a viral homolog of BCL2. BCL2 is a gene, it's a human oncogene, and it functions by blocking apoptosis or programmed cell death. And so that was transformative to me and took other people a while to realize the importance of that, that one novel function of cancer is to evade cell death. That field grew. We and others contributed to cloning the other genes that regulated apoptosis. We figured out how it all-- the mechanism by which it worked, and the pharmaceutical industry started developing inhibitors of BCL2 to promote apoptosis in cancer. And that was the ultimate goal, was to make tumor cells die and have a drug that will do that. And once that happened, the field of apoptosis, I think, sort of, we accomplished what we had wanted to accomplish. We understood everything, and that led to the development of the first of many drugs that were in clinical trials. And in fact, my lab is still involved with taking those drugs and putting them in patients and optimizing their use in solid tumors. So while the field of apoptosis matured to the point where things were being translated, we made a serendipitous discovery. We had engineered tumor cells to

3. 10:00 – 17:20

   Defining apoptosis and its role in cancer prevention

   1. EWEileen White10:01

      be unable to undergo apoptosis. They were refractory to being able to commit suicide.

   2. PAPeter Attia10:08

      Can we pause for a second there, Eileen, and just let's explain to folks exactly how apoptosis works because shortly we're going to obviously contrast this with autophagy. They have common threads, but they're different. So let's go down the, the path of what does it take to get a cell to undergo programmed suicide?

   3. EWEileen White10:26

      So there's a family of proteins called the BCL2 family. They come in different flavors. There are the BCL2-like proteins which inhibit apoptosis, so they keep tumor cells alive. And BCL2 is the prototypical member of that family and is upregulated and amplified and translocated in many cancers to do exactly that. And there are antagonizers of BCL2 and its related proteins. These are called the BH3-only proteins, and they are often activated to inhibit BCL2 to trigger apoptosis. And then there's the core apoptotic machinery that triggers apoptosis, and this is Bax and Bak. They reside in the mitochondrial membrane, and when they're triggered to undergo apoptosis, they oligomerize and poke holes in the mitochondrial outer membrane. That releases proteins that activate proteases to grade the cell. And BCL2 and BCLXL, all the anti-apoptotic proteins are involved in an- antagonizing this process.

   4. PAPeter Attia11:45

      And what are some of the things that would have to be going wrong in a cell for it to go down that suicidal pathway? So for example mitochondrial injury that is irreversible, genetic mutation that is unfixable. Like, what are the suite of things that basically take a cell down the path of, "I can't fix this, and being around here and replicating is gonna be dangerous to the host. I gotta take myself out of the game"?

   5. EWEileen White12:12

      Right. So mitochondrial damage can certainly trigger apoptosis, but probably the best way to explain it is by using the example of P53. So P53 is a tumor suppressor and a transcription factor, and some of the transcriptional targets of P53 are proteins like Puma and Noxa, which are these antagonizers of BCL2 and activators of Bax and Bak. P53 is a tumor suppressor. One of the functions is to promote apoptosis to prevent an emerging cancer cell from progressing. One mechanism by which P53 does that is by turning on the transcription of Puma and Noxa, and then that will antagonize BCL2 and initiate apoptosis. So then the question becomes: what activates P53 to do that? And that could be a long list of things from DNA damage, from oxidative stress, and so forth. So you could think of something bad happens to an emerging cancer cell, and then P53 gets activated, and one of the tumor suppression functions of P53 is to turn on these promoters of apoptosis that antagonize BCL2.

   6. PAPeter Attia13:38

      Now, loss of function in P53 probably accounts for half of all cancers, correct?

   7. EWEileen White13:42

      Right.

   8. PAPeter Attia13:43

      And I assume that you have to lose both copies of it, or is losing one copy sufficient?

   9. EWEileen White13:49

      Well, what happens in most of the time is not deletion of P53, but rather a point mutation-

   10. PAPeter Attia13:57

       That reduces function

   11. EWEileen White13:58

       ... it's more of a dominant negative.

   12. PAPeter Attia14:00

       Mm-hmm.

   13. EWEileen White14:00

       So in fact, there's even evidence that there's a gain of function.

   14. PAPeter Attia14:04

       Mm.

   15. EWEileen White14:04

       So there are hotspot mutations in P53 that are very common in cancer, and P53 functions as a heterodimer, and what these mutant P53s do is that they end up entering into a dimer with wild-type subunits, and that interferes with the function of the complex. So yes, in that respect, it can be a loss of function of the P53 heterodimer, but there's evidence that it not only causes a loss of function, but it actually may do other things as well that are cancer promoting.

   16. PAPeter Attia14:42

       That's just a great example of the nuance of evolution, right? I mean, in med school, the classic teaching, you know, when, a hundred years ago for me was P53, loss of function, oncogene, gain of function, black and white. Of course, it's never black and white.

   17. EWEileen White14:54

       Right.

   18. PAPeter Attia14:55

       So what is the wreckage of apoptosis? So when a cell undergoes apoptosis, to everything outside the cell, inclusive of the immune system, what becomes visible? In other words, does an apoptotic cell, once it dies, elicit any immune response, or does the process of apoptosis yield sort of an inert body of cellular matter that just goes away?

   19. EWEileen White15:21

       I'm not so sure I'm the best person to answer that question. I think the whole idea initially was during the process of apoptosis, you would get protein degradation and packaging of pieces of the dead cells into these apoptotic bodies, and then that would reduce inflammation. And then there's evidence that macrophages can then go and take up these apoptotic bodies, and that may facilitate antigen presentation and so forth.

   20. PAPeter Attia15:53

       So it's possible, for example, that if you have a cell that has become cancerous, either through a gain of function, loss of function, but whatever, there's some mutation that now renders this cell to go down a pathway of cancer. It, fortunately, it undergoes the apoptotic transition. The macrophages take it. Is it likely that you get an immune response to that that is protective in the long run against similar mutations? Because, I mean, even though the macrophage is part of the innate immune system, does that ever translate to the adaptive immune system such that you gain some long-term immunity from that specific type of mutation?

   21. EWEileen White16:28

       Yes, I think something like that occurs, and I just think I'm the wrong person to answer that question. I could give you the better names of people that can do a better job. But the, I think the best way to compare it is to contrast it with necrotic cell death.

   22. PAPeter Attia16:44

       Mm.

   23. EWEileen White16:44

       So in apoptosis, you have proteolytic degradation and, of a cell and packaging it into these bodies, and you say, "Well, does that limit inflammation?" Well, the way to explain how it does is to compare it to a different form of cell death like necrosis. So necrosis is cells lyse, and that is very pro-inflammatory. You have nucleic acids released. You have essentially everything is released.

   24. PAPeter Attia17:16

       Including mitochondrial content, which is probably the most immunogenic given its bacterial

4. 17:20 – 29:15

   How cancer cells use the autophagy pathway to survive

   1. PAPeter Attia17:20

      origin of the DNA.

   2. EWEileen White17:22

      Absolutely, and so-

   3. PAPeter Attia17:23

      Apoptosis, but what I'm hearing you say is apoptosis is much cleaner than necrosis.

   4. EWEileen White17:27

      Absolutely.

   5. PAPeter Attia17:29

      So now let's talk about autophagy. Let's contrast autophagy with apoptosis.

   6. EWEileen White17:34

      That's right. Well, before we get to that, I should go back to your original question of, like, how did we start working on autophagy? And this sort of bridges us to what you just mentioned. So when we disable apoptosis in a cancer cell, it can't commit suicide, and we're doing that all the time, and we could show that then the tumor cells become more tumorigenic. But what we didn't expect was the extraordinary propensity for survival. We could leave the cells out and put them in buffer. They wouldn't die under extraordinary circumstances that we couldn't explain. So why would a cell that just couldn't commit suicide survive in buffer with no nutrients at all?

   7. PAPeter Attia18:25

      And just for context, this is the mid-'80s, late '80s?

   8. EWEileen White18:28

      This is the mid-'80s.

   9. PAPeter Attia18:30

      Okay.

   10. EWEileen White18:30

       No, it's probably later than that. It was probably early 1990s. And so it was a conundrum. I mean, just because a cell can't commit suicide doesn't explain how it can be a cancer cell can just sit in buffer and be fine. And we puzzled over this, like, "How can this be?" And then we discovered that what these cells had done was turned on autophagy and were using that for survival.

   11. PAPeter Attia19:00

       Before you go down that path, help me understand something. What did you observe about those cells that were sitting there in the absence of nutrients surviving? Did you notice any metabolic changes that were unusual? Like, what was your clue that they were able to usurp the environment they were in?

   12. EWEileen White19:19

       Yeah, it was an act of desperation. [chuckles] We tried a bunch of things, and nothing was informative. And then I told the people in the lab, "Why don't we just look at these cancer cells under the electron microscope, and that way we can-

   13. PAPeter Attia19:34

       [laughs]

   14. EWEileen White19:34

       ... we can see everything." 'Cause we couldn't understand how they could be surviving a buffer. And when we got the electron micrographs back, we saw something we had never seen before, and all these double membrane vesicles all over the cell. And so that, when we finally fig- oh, those are autophagosomes, which we had never, ever seen.

   15. PAPeter Attia19:55

       But wait, how did you... I mean, first of all, this is just, to me, one of the beautiful moments in science that I think, I think it's so important for people who don't do science for a living to understand that while science is 99% failure, every once in a while you have a moment like that.

   16. EWEileen White20:12

       A eureka moment.

   17. PAPeter Attia20:13

       Yeah. It probably makes up for 10 years of failure-

   18. EWEileen White20:17

       Yes

   19. PAPeter Attia20:17

       ... when you realize in that moment you are seeing something that has never been seen before, and therefore, this is the cusp of new knowledge.

   20. EWEileen White20:27

       That's right. That's happened to me a bunch of times in my career, which is fortunate, and this was one of those moments. And then we started reading, "Well, what are these autophagosomes? What do they do?" And then when we realized from when we looked in the yeast literature, they were meant to capture intracellular proteins and organelles and bring them to the vacuole or the mammalian lysosome for degradation and recycling, and that this was a mechanism by which yeast survived starvation.

   21. PAPeter Attia20:57

       And what was the tumor line or what was the cell line you were doing this in?

   22. EWEileen White21:01

       At the time, we were using kidney cancer cell lines.

   23. PAPeter Attia21:05

       Uh, mice or human?

   24. EWEileen White21:07

       These were mouse.

   25. PAPeter Attia21:08

       But it was basically the first time this had been seen in mammalian cell line?

   26. EWEileen White21:12

       No, I think people had seen au- autophagosomes before. I mean, you gotta remember in the olden days when electron microscopes were first available, that that's one of the things that people did was describe all kinds of different processes. So autophagosomes were known to exist, but there was very, very little information, almost no information on autophagy and cancer at the time. So we went into this area where there was almost no information. And so the first question we asked is, "Okay, well, the yeast data tells us that when you see autophagosomes, that means cells are starved, and they're recycling, and they're using this to survive." And we hypothesized that that's what was going on in these cancer cells. And if that was the case, if autophagy was a survival pathway in cancer, that was a game changer. We had to understand it, and we had to demonstrate that that's what was actually happening. And then if that was the case, if cancer cells had usurped the autophagy pathway for their survival, then we needed to inhibit autophagy for cancer therapy. The first thing we did was we looked to see what would happen if we inhibited autophagy in these cancer cells. And the answer was very simple. In many, many circumstances and many different cell lines that we looked at, when you inhibited autophagy, the survival of the cancer cells was reduced.

   27. PAPeter Attia22:55

       Let me interject for a second and ask a question. I don't know if you ever did this experiment, but if you took the kidney line and the kidney cancer line, so basically the same histology from the same tissue from the same animal, but one has the oncogenic properties and one does not, and you put them in the identical nutrient-deprived stress, can you quantify the amount of autophagy or the efficiency with which those two cells undergo autophagy? In other words, is cancer simply preserving the autophagy capacity that it had as a non-cancer cell but not enhancing it or not having any attenuation of it? Is it simply just, hey, this just happens to be something that gets preserved as you go from non-cancer to cancer? Or is there some qualitative or quantitative change in the character of autophagy as a cell mutates?

   28. EWEileen White23:47

       That's interesting. So let me see if I can unpack that. So if you have... The general observation is that normal cells in the fed state don't have autophagy on. It functions as at a very, very low level. And if you starve cells or mammals for nutrients, then there's a massive upregulation of autophagy. What was striking about the cancer setting was that even in the fed state, autophagy was elevated.

   29. PAPeter Attia24:21

       Ah, so there, there is a fundamental difference there.

   30. EWEileen White24:24

       Yes.
5. 29:15 – 32:45

   Stressors that induce autophagy

   1. EWEileen White29:15

      circumstances where autophagy might be necessary, but the basic process is surprisingly the same.

   2. PAPeter Attia29:23

      What are some of the other stresses that induce autophagy? And let's maybe just for the moment even start with just in a normal cell. So let me sort of resynthesize what we've talked about. Clearly, nutrient deprivation is one of the biggest triggers for autophagy. And I mean, maybe just for the sake of time, I'll kind of throw this out there, and you can correct me if I'm wrong, but I've always sort of thought of this through three pathways at the sort of mechanistic level. So you have sort of the mTOR pathway, which is mostly sensing amino acids. You have the AMPK pathway, which is mostly sensing energy and ATP in general. And then you have sort of the acetyl-CoA protein deacetylation pathway, which is also just basically sensing substrate of fatty acid and glucose. Is that sort of a fair way to say that those are three ways that nutrient, low nutrients can still trigger the same pathway?

   3. EWEileen White30:15

      Yeah, and I think you could add on to that Stresses that result in organelle damage, such as depolarization of mitochondria or dysfunction of mitochondria, activation of protein misfolding, and generation of protein aggregates. So I think there's the things that are directly related to metabolic signaling that you've mentioned, but then there are other stresses that also can tie into the autophagy pathway.

   4. PAPeter Attia30:44

      Are there other stresses like the nutrient that are stresses that come from outside the cell to inside the cell? So the, the protein misfolding, the mitochondrial depolarization, those are things that are occurring as damage within the cell that stress. Do we know anything, for example, about temperature? Do heat shock proteins stimulate autophagy in extremes of temperature? Does exercise, I mean, which obviously is in the short term quite stressful, how potent is that at inducing autophagy in a normal cell?

   5. EWEileen White31:13

      So temperature-wise, I would fully expect that temperature extremes would induce protein misfolding and induce autophagy as a remedy for that. But I, I don't recall any studies on that. In terms of exercise, that's very well studied that exercise induces autophagy very potently, and you actually need autophagy too, because exercise damages the muscle.

   6. PAPeter Attia31:42

      Mm-hmm.

   7. EWEileen White31:42

      And autophagy is one of the processes that helps mitigate the damage that occurs during exercise.

   8. PAPeter Attia31:50

      What about hypoxia?

   9. EWEileen White31:51

      Oh, potently. Hypoxia potently induces autophagy.

   10. PAPeter Attia31:55

       Wow.

   11. EWEileen White31:56

       And in fact, one of the first things we did was when we looked at tumors, tumors are well known to have hypoxia in the center. When we engineered tumor cells to be genetically deficient for autophagy and you look at them, they're completely hollow.

   12. PAPeter Attia32:16

       Meaning they have no organelles, nothing?

   13. EWEileen White32:18

       Not the cells are hollow, the tumor is hollow.

   14. PAPeter Attia32:21

       Oh, wow. The further the cells get from a blood supply, meaning the more susceptible they are to hypoxia, they're dead.

   15. EWEileen White32:28

       Right. So if you take a tumor, if the middle is hypoxic-

   16. PAPeter Attia32:32

       Mm-hmm

   17. EWEileen White32:32

       ... that's where your autophagy is most active. And if you genetically ablate autophagy in the tumor, you end up with a hollow tumor because the tumor cells in the middle don't survive.

   18. PAPeter Attia32:43

       Yeah. So it does come back to this idea that we talked

6. 32:45 – 40:00

   The importance of autophagy in the brain and liver

   1. PAPeter Attia32:45

      about earlier about hypoxia being potentially one of the things that autophagy is protecting cancer from.

   2. EWEileen White32:50

      Absolutely.

   3. PAPeter Attia32:51

      How easy is it to create an animal model that is unable to undergo autophagy? How difficult is that from a knockout perspective?

   4. EWEileen White32:59

      Well, it's been done, and we've done it, and it can be done different ways. So the original mouse strains that were made were deficient in either of two of essential autophagy genes, one called Atg5 and another one called Atg7. And these mice were developed in Japan, and these mice are born, but they fail to survive the neonatal starvation period. So when mammals are born-

   5. PAPeter Attia33:26

      Meaning once they are cut off from an umbilical nutrient source, it's almost like they have a glycogen storage disease. You know those conditions where you can't produce any glycogen? Uh, it's uniformly fatal if not treated the moment you're cut off from an umbilical source of nutrient.

   6. EWEileen White33:40

      Right. So that neonatal starvation period between the cutoff of the placenta and suckling is a common feature in mammals, and there's potent induction of autophagy during that period. I can't speak for humans, but certainly I would think so. And in mice, that's exactly what happens. And so these autophagy deficient newborn mice don't survive.

   7. PAPeter Attia34:09

      Wow. That really... I mean, again, I think that simply underscores the evolutionary preservation of something. If you knock it out, it is uniformly fatal. Do not pass Go, do not collect $200. You're gone.

   8. EWEileen White34:22

      And then what we did was ask a different question. It was like, "What happens in an adult mouse?" So in the, a newborn mouse, it's very different situation because any newborn mammal, they don't have any fat.

   9. PAPeter Attia34:36

      Right. They have no reserves.

   10. EWEileen White34:37

       They have no, no reserves. And so when the Japanese group did the extraordinary thing of trying to force feed these autophagy deficient newborn animals, then they didn't extend their survival very much.

   11. PAPeter Attia34:50

       Now, was this Yoshinori's group?

   12. EWEileen White34:51

       This was Noboru Mizushima and the Komatsu group-

   13. PAPeter Attia34:56

       Okay

   14. EWEileen White34:56

       ... I believe. And I think it was coming from those two labs.

   15. PAPeter Attia35:00

       So what happened in that experiment?

   16. EWEileen White35:02

       They discovered that the mice died shortly after birth, and then they realized that... Well, they suspected they had a metabolic problem, and they weren't suckling because they were probably too ill to by the time-

   17. PAPeter Attia35:17

       Mm

   18. EWEileen White35:18

       ... they were, would've been able to. So they force fed them, and that allowed them to live for 24 hours, but they still died anyway.

   19. PAPeter Attia35:27

       And then are you able to induce an autophagy knockout in an adult?

   20. EWEileen White35:32

       Yeah. So that's what we did because we realized that the newborn animal is-

   21. PAPeter Attia35:37

       It's just too fragile

   22. EWEileen White35:38

       ... too fragile. They have no nutrient reserves. And actually in the setting of cancer, we're thinking of you want to treat an adult with a tumor. So what's happening in autophagy in a newborn animal isn't even relevant.

   23. PAPeter Attia35:52

       Right.

   24. EWEileen White35:53

       And so we engineered mice where we can take an adult mouse and give the mice a chemical so that an essential autophagy gene will be deleted throughout the entire animal. So one day they're an adult mouse with autophagy, and then a few days later they're an adult mouse with no autophagy. And these mice were very extraordinary. They lived for two to three months. And then they died predominantly of neurodegeneration. Autophagy is very important in the brain over the long term. But if we fasted the mice, they were all dead within 16 hours.

   25. PAPeter Attia36:33

       Let's unpack that again. That's pretty remarkable. So you take a normal mouse that's got through the vulnerability period of infancy, and you genetically knock out its capacity for autophagy. The first thing you observe is if you fast it for 16 hours, which admittedly is a pretty long fast for a mouse, that might be the equivalent of fasting a human for a week. But that degree of nutrient deprivation is uniformly fatal. If you continue to feed them well, they only survive another couple of months because they ultimately succumb to neurodegeneration, suggesting that the role of autophagy in preventing neurodegeneration is essential. And it's really not surprising when you think about the role, everything you talked about with protein misfolding. I mean, when you start to think about the toxicities that are driving neurodegeneration, using Alzheimer's disease specifically as an example, there's a lot of crap that's basically getting accumulated in neurons. This would be an elegant way to suggest that autophagy is keeping that at bay.

   26. EWEileen White37:34

       Exactly right. So one other way of looking at it is what tissues are more autophagy-dependent than others?

   27. PAPeter Attia37:44

       Exactly.

   28. EWEileen White37:44

       Brain would be really important, and there are a few others. And what we noticed when we looked at the mouse that lacked autophagy when we had genetically deleted the autophagy gene in the adult mouse was that there were tissues like the brain that were very sensitive, and there were other tissues like the lungs that didn't have any phenotype.

   29. PAPeter Attia38:07

       So wait, in other words, when those animals ultimately die of neurodegeneration and you undergo the pathology analysis, obviously, the brain is where you see the cause of death. You're saying in the lung, it looked completely normal.

   30. EWEileen White38:19

       Relatively normal.
7. 40:00 – 42:30

   The mechanisms that can trigger autophagy to support longevity

   1. PAPeter Attia40:01

      I want to come back to this later on in the discussion, but I'll just plant the seed now. Obviously, fasting is one of the most potent stimulators of autophagy. I spend a lot of time thinking about how does fasting fit into our toolkit of longevity. A big part of longevity, in fact, probably the single most important piece of longevity when it comes to the lifespan aspect of it, so you know, you think of lifespan versus healthspan, how long you live versus how well you live. On the how long you live front, I think it's very safe to say, based on all of the animal data and frankly, all of the centenarian data, that the key to living longer is delaying the onset of chronic disease. So even when you look at centenarians who are genetically gifted with tools to live longer, if you unpack what the gift is, it's delaying the onset of the disease, not living longer once you have the disease. So the centenarians, once they get cancer and once they get heart disease, they die at about the same rate over the same duration as the rest of us schmucks. The difference is they get those diseases 20 to 25 years later. And again, that suggests to me that if you want to live longer, you have to delay the onset of these things, not live longer once you have them. And so it's hard to think that fasting doesn't play an essential role in that when you realize the role that fasting plays in the mitigation of Alzheimer's disease and metabolic disease. Of course, what we're going to come back to in a second is cancer, which seems to be this conundrum. This is the needle we're going to want to thread a little later down the line. I'll plant the seed now, but I do want to come back to the idea of ways that we can also induce autophagy sort of pharmacologically or chemically. The first thing that would jump to your mind is anything that mimics fasting. The first thing that comes to mind would be metformin, rapamycin, things like that, that what we talked about earlier, just for the listener to sort of tie this together, we talked about these huge pathways that tell the body nutrients are scarce. So when mTOR activity is down, that's a sign that we're deficient in amino acids. Well, we can also do that with rapamycin. When AMPK is up, that's the cell being told we're deficient in ATP. Another way you can do that is to give metformin. We haven't talked about sirtuins yet. Maybe I'll pause for a moment. Do we have any sense of what sirtuin activity does in autophagy?

   2. EWEileen White42:27

      I'm not familiar with that literature.

   3. PAPeter Attia42:28

      Okay. I was gonna

8. 42:30 – 46:45

   Evidence for cancer treatment by blocking autophagy

   1. PAPeter Attia42:30

      say, 'cause then you could get into the whole NAD versus NADH ratios and how that might factor into it. So again, I'm really curious about this through a clinical lens as well, which is what is the suite of products? But almost just saying that out loud so between the two of us we remember to come back to this. But I now kinda wanna get back to your story, which is we've got these mice, you've got this much more elegant experiment now, which is you're actually going after the phenotype of interest, which is in an adult in which you inhibit autophagy. What was happening in that animal if it had cancer? So did you ever do the experiment where you had an adult with cancer, then you knock out autophagy?

   2. EWEileen White43:07

      That's actually one of the reasons we made that mouse. So we had two questions we wanted to answer. One was if you inhibited autophagy in an adult mouse, what would happen? Because if they died in an hour, then targeting autophagy for cancer therapy would be pointless.

   3. PAPeter Attia43:25

      Especially if you can't do it specifically.

   4. EWEileen White43:27

      That's right. So the answer was they didn't die in an hour, they died in two or three months, which was actually good news because that meant that there was a potential window of opportunity for inhibiting autophagy for cancer therapy.

   5. PAPeter Attia43:41

      And I'm sorry, Eileen, when they died in two to three months, was it still from the neurodegenerative disease?

   6. EWEileen White43:45

      Yes. Yes.

   7. PAPeter Attia43:45

      And did they still have cancer at the time of death?

   8. EWEileen White43:48

      We had to first make a mouse that lacked-- where we could switch off autophagy and find out what happened to that mouse, okay? So we did that, and we saw that they died of neurodegeneration in two or three months, which was good. If they died immediately, then we would've stopped. There would be no point in trying to make cancer in that animal. But we did learn that they were intolerant to fasting, which was perfectly consistent with everything we knew about what autophagy functionally did. So then we moved to the second step, was to do the experiment that you just suggested to make cancer in that mouse, and then after the mouse had cancer, to then shut the autophagy pathway off, and then to ask the key question: which died first, the mouse or the tumor?

   9. PAPeter Attia44:38

      Yeah.

   10. EWEileen White44:39

       And the answer was the tumor died first.

   11. PAPeter Attia44:42

       Wow, okay. So then here's the gangster question. Once the tumor died, could you reactivate autophagy to prevent the neurodegeneration, or is it a one-switch direction?

   12. EWEileen White44:52

       That required a different type of mouse model. So what we were doing was making a mouse with cancer, and then once the mouse had lung cancer in this case, we deleted an essential autophagy gene in the entire mouse, tumor and all, but the gene was gone. So it wasn't like we could turn autophagy back on in that model. But since then, one of my trainees in collaboration with a lab in the UK, they have developed a model where they can toggle autophagy off and then back on again. And what they've seen is a remarkable capacity of the normal tissues to restore themselves. So the experiment would be to have a mouse to induce an shRNA to a specific autophagy gene to down-regulate the expression and inhibit autophagy that way, and then later on take that shRNA away or shut it off and restore normal autophagy in the mouse. And you see a lot of capacity for the tissues to restore themselves back to normal.

   13. PAPeter Attia46:05

       So that experiment basically becomes the proof point that says targeting autophagy in cancer makes sense. That's probably the most elegant description you could provide of that.

   14. EWEileen White46:18

       That's right. I think it would be better if we had specific targeted therapies against some of the enzymes in the autophagy pathway, because these are all genetic experiments, and it's not exactly the same to-

   15. PAPeter Attia46:35

       Right. You might not get the complete-

   16. EWEileen White46:36

       Right

   17. PAPeter Attia46:36

       ... penetration with a drug.

   18. EWEileen White46:38

       Or inhibiting a protease is not exactly the same as deleting the gene. But this is all

9. 46:45 – 52:40

   Types of cancer that are most autophagy-dependent

   1. EWEileen White46:45

      what's called proof of principle that the concept of inhibiting autophagy is, in cancer is valid.

   2. PAPeter Attia46:53

      So what do we know today about what you've just described as it pertains to two things? So I want to slice the data across two variables. The first is tissue type or histology of cancer, and the second is underlying genetic mutation. So I know that a lot of what you're describing is clearly true in KRAS mutation. What about other drivers?

   3. EWEileen White47:18

      We and a number of other cancer labs that use genetically engineered mouse models for cancer have been banging away at that for a number of years. And what we've learned is that KRAS-driven lung cancer and pancreatic cancer are extraordinarily autophagy-dependent, and you do it, you know, make the mouse models, and the tumors are very susceptible to the functional loss of autophagy.

   4. PAPeter Attia47:46

      Can you briefly tell folks what a KRAS-driven cancer does? Like, what is it about the mutation that drives the oncogenesis?

   5. EWEileen White47:53

      So KRAS is a GTP-binding protein that is responsible for activating what's called the MAP kinase pathway, and this pathway is very key in driving cell proliferation. And so cancers have a mutation in RAS or mutations in RAS that leave it in the GTP-bound or on state. So there's perpetual growth signaling through the MAP kinase pathway.

   6. PAPeter Attia48:23

      Which of course is the hallmark of cancer, which is it's unresponsive to cell signaling, and when you are fixed in the on position, you can't turn off, and basically that is cancer.

   7. EWEileen White48:32

      That's right. And what's particularly interesting about RAS-driven cancers is that we have been very unsuccessful in drugging RAS. And there's recent hope that the cysteine, the particular subset of the mutations in RAS that involve a cysteine residue, that there are now drugs that target that. There's hope after decades of failure.

   8. PAPeter Attia48:58

      Is the primary issue in the failure to drug RAS that you can't do it without creating toxicity for other cells that are non-cancer, or that it has too many workarounds to whatever you put in place?

   9. EWEileen White49:11

      I think too many workarounds is a common problem. What they've done is that they said, "Okay, if targeting RAS is difficult, then let's go downstream of RAS."

   10. PAPeter Attia49:20

       And try MAP kinase. Yeah.

   11. EWEileen White49:21

       Right. Right. So there are inhibitors of RAF, MEK, and ERK, which are downstream of RAS, and those are actively in use in the clinic, but they seem to be not durably effective in RAS-driven cancers because of the workarounds.

   12. PAPeter Attia49:41

       Yeah. So are there mutations or mutant drivers of cancer that we know are not dependent on autophagy and unresponsive to the autophagy blockade?

   13. EWEileen White49:52

       Yeah. It seems like there's a spectrum. So RAS-driven cancers are particularly sensitive. BRAF-driven cancers like BRAF V600E is a common BRAF oncogenic mutation, and those cancers are particularly sensitive, and those-- The ones that were examined were lung cancers and melanoma. The BRAF V600E mutation in melanoma is very common. Homologous recombination deficient breast cancers, and those would be, well, I mean, those would be models of hereditary breast cancer. Those are very sensitive to loss of autophagy. APC deficient colon cancer is another example.

   14. PAPeter Attia50:38

       What about non-APC-driven colon cancer, which of course is the majority of it? What do we know about that?

   15. EWEileen White50:45

       I don't think I can remember seeing a paper. I remember the APC deficient model.

   16. PAPeter Attia50:51

       Mm-hmm.

   17. EWEileen White50:51

       That's, that's in fact the most commonly used model.

   18. PAPeter Attia50:55

       Anything we know about prostate cancer or other hormone-sensitive breast cancers?

   19. EWEileen White50:59

       So prostate cancer is sensitive. We did that work. And hormone-sensitive breast cancer, I'm not recalling right now. But there are a long list of cancers that are sensitive. The sensitivity is not all equal. For example, BRAF-driven cancers are very sensitive, more so than RAS-driven lung cancers. You just compare lung-- BRAF lung cancer to RAS lung cancer. The BRAF mutant lung cancer is more sensitive. The most sensitive cancer that we've encountered is, in fact, RAS-driven lung cancer with LKB mutations, and this makes a lot of sense, too. So one of my trainees, who has her own research lab, hypothesized that... We sat down and we thought, "What cancer would be, would you predict to be most autophagy dependent?" And it should be a cancer with loss of LKB1. LKB1 is a tumor suppressor gene that's involved in activating AMP kinase.

   20. PAPeter Attia52:02

       Mm-hmm.

   21. EWEileen White52:02

       And AMP kinase activates autophagy as a survival mechanism to low energy. And so there are a whole class of lung cancers that have lost LKB1, and as a result, they can't activate this protective mechanism. This is Dr. Jessie Guo. She made this mouse model, RAS-driven lung cancer without LKB1. And lo and behold, when you delete an essential autophagy gene, you abrogate tumor genesis. So it makes a huge amount of sense. LKB deficient RAS-driven lung cancer is probably

10. 52:40 – 59:15

    The autophagy paradox

    1. EWEileen White52:40

       the number one sensitive tumor.

    2. PAPeter Attia52:44

       So how do we reconcile these two observations that almost seem to have a difficulty coexisting? So the first is everything you've just stated, which is pretty clear and unambiguously suggesting that autophagy is, at least for a number of cancers, an important part of their survival and proliferation. And we contrast that with an abundant body of literature that suggests that when you combine fasting, which is a potent inducer of autophagy, with chemotherapy, for example, you enhance its efficacy, and we can speculate about why that might be the case. These two things, although not directly comparable, seem a little bit at odds. How do you think about those things?

    3. EWEileen White53:35

       I would probably think about it in a slightly different way. So if you want to get at the two different roles of autophagy, one is cancer cells usurping it and turning it on for their own survival, then the other side of it is when we know that autophagy is protective. We know what happens if you have a mouse without autophagy. Many terrible things happen. It takes a while, but the mice die of neurodegeneration.

    4. PAPeter Attia54:02

       Can I interrupt for one sec? And I'm sorry to do this, but I just, I'll forget this question. I want to come right back to your thought. In those animals that died of neurodegenerative disease after two to three months, did they show an increase in tumor genesis in any other tissue?

    5. EWEileen White54:17

       No, they don't. But if you make a mouse where you bypass the neurodegeneration by knocking out an essential autophagy everywhere else, okay, but not the brain Then those mice will get benign hepatomas, so benign tumors of the liver.

    6. PAPeter Attia54:34

       Mm-hmm.

    7. EWEileen White54:35

       But that makes sense, too. Think about autophagy in normal tissues. We know it's important 'cause if you knock autophagy out on a mouse, there's tissue specific but gradual deterioration ultimately le- leading to neurodegeneration, and you end up with steatosis l- you know, fatty liver disease. The brain phenotype can be explained, as we discussed before, neurons in the brain need this protein and organelle quality control function. They're post-mitotic. They have to have a way of getting rid of the garbage. In the liver, what happens when you damage the liver?

    8. PAPeter Attia55:11

       It regenerates. It's got-

    9. EWEileen White55:13

       It regenerates

    10. PAPeter Attia55:13

        ... infinite capacity.

    11. EWEileen White55:14

        That's right. But what happens when you artificially-

    12. PAPeter Attia55:17

        Unless there's too much inflammation.

    13. EWEileen White55:19

        Exactly. So you end up with when you inactivate autophagy in liver, you end up with these chronic cycles of damage, repair, and chronic inflammation, and that is oncogenic. And that's ni- you know, it's particularly obvious in the liver.

    14. PAPeter Attia55:34

        The pancreas as well.

    15. EWEileen White55:35

        Exactly.

    16. PAPeter Attia55:36

        Very, very sensitive to that inflammation.

    17. EWEileen White55:37

        So I think what this is telling us is something very important. It's telling us that a main function of autophagy in tissue homeostasis is to preserve cellular function to be normal, to prevent chronic damage and inflammation. And tissues that are susceptible to cancer as a result of chronic damage and inflammation, autophagy is highly protective.

    18. PAPeter Attia56:07

        Which again, think about how complicated this is. Now I'll bring us back to the question I posed a moment ago, but using this example. Why does NAFLD ultimately lead to cancer? Because if you have enough accumulation of fat, you get enough inflammation, you're gonna get hepatocellular carcinoma. Same with pancreatic cancer. Highly-- You know, this is why alcohol is such a horrible molecule, so toxic to the pancreas, to the liver, and you sow those seeds of inflammation, and lo and behold, you're increasing this risk of cancer. So on the one hand, we know that autophagy helps ameliorate that. It cleans that up. It buffers that. At the same time, we just realized a moment ago, oh, boy, once you do get pancreatic cancer, it's a KRAS-driven cancer. Autophagy is helping it.

    19. EWEileen White56:50

        That's right.

    20. PAPeter Attia56:50

        So now let's come back to the question I posed a moment ago that I so rudely interrupted [laughs] you answering, which was how do you reconcile these?

    21. EWEileen White56:57

        I think it's a matter of thinking of the role of autophagy in cancer as being context dependent. On the one hand, functional autophagy can delay the onset of chronic damage and inflammation that are known causes of cancer, in particular tissues such as the pancreas and the liver, amongst a few others. So I think that stimulating autophagy through fasting or through pharmacologic means at one point can be thought of as preserving health.

    22. PAPeter Attia57:30

        Right.

    23. EWEileen White57:30

        But once you have a cancer, I think it's a different ballgame. And at that point, it's a completely different context. And in that setting, what we've learned is inhibiting autophagy is preferentially damaging to the tumor compared to the normal tissues.

    24. PAPeter Attia57:51

        And then going back to the other literature which looks at the efficacy of fasting combined with chemotherapy, which is superior to just chemotherapy, do you think that the reason for that is that the chemotherapy itself, maybe once you, you're rendering the cells more sensitive to chemotherapy and also potentially generating a more durable immune response? 'Cause one interpretation of what you're saying is a person with cancer should never be calorically restricted.

    25. EWEileen White58:22

        I don't know. That's, uh, going too far. I would say that, yeah, I don't know that you can equate-

    26. PAPeter Attia58:28

        Mm

    27. EWEileen White58:28

        ... caloric restriction with the loss of autophagy or regulation of autophagy because I think they're not equal things, because I think that caloric restriction is limiting tumor nutrients. And so I think what that's doing in the context of cancer therapy needs to be better understood. I'm just not sure that we know what's happening there.

    28. PAPeter Attia58:56

        If I'm hearing you correctly, you're saying, look, it, it might be that we can't necessarily say that fasting isn't helpful in cancer because while it may be counterproductive from the standpoint of autophagy, that may be offset by other things that are beneficial, such as the reduction of overall nutrients and inflammation that accompany this.

    29. EWEileen White59:14

        Exactly right.

11. 59:15 – 1:13:00

    Finding a molecular signal for autophagy

    1. PAPeter Attia59:15

       Yeah. To me, of all of the areas of autophagy that have me scratching my head the most, it is this question of given that fasting is one of our most potent ways to stimulate it, in fact, I would argue it's more potent than metformin, which is an AMPK activator, more potent probably than exercise. I mean, it might be the most potent thing we can do to turn this amazing tool on. How do we think about using it in disease prevention and disease treatment? And they aren't necessarily the same thing.

    2. EWEileen White59:44

       I completely agree. And in fact, I would ask a question of you. So there's, uh, multiple efforts in the biotech industry to identify pharmacologic agents that are potent stimulators of autophagy. And I think their idea is, is that normal, healthy people will take a pill, autophagy will be turned on, and there'll be some fountain of youth type thing that-

    3. PAPeter Attia1:00:09

       Yeah. Spermidine-

    4. EWEileen White1:00:09

       Right

    5. PAPeter Attia1:00:10

       ... is one of the things that people are talking a lot about, right?

    6. EWEileen White1:00:12

       So why not cultivate the use of fasting instead?

    7. PAPeter Attia1:00:19

       I will tell you exactly why, Eileen, and you-- I love how you have fed into-- It's almost like you can read my mind and know where I'm gonna go with this discussion. I think a big part of it is we don't have the tools to measure the signatures of autophagy. In other words, if a patient comes to me and says "Peter, I want to do whatever I can to enhance autophagy because I have now bought into the idea that it is going to basically protect me from every chronic disease." And I would say, "Yeah, I agree with you." And they say, "Great. Fasting seems like a great way to do it." I'd say, "You're absolutely right." And they say, "Well, how long do I need to fast, Peter?" Guess what I get to say? "I don't know." And I'll tell you in, in reality what I say. I say, "Well, look, I'm really sure that after about seven days of nothing but water, autophagy is fully cranked, and I'm also really sure that if you just go 12 hours without a meal, you probably haven't done anything." Where I struggle is we're between them. Now, I wanna share with you some personal experience, and I want you to weigh in on it, and then I think maybe we can pivot off into actually kind of going back to what you and I spoke about over the phone five or six years ago, which is what would a molecular signature for autophagy look like? And again, I think this is-- I put this in the top three most important translational questions in my field. In other words, as I think about the practice of medicine as it pertains to longevity, it's our inability to understand how to quantify the benefit of nutrient deprivation, in other words, our inability to dose it, that is our greatest, certainly among our top three detriments to using this incredibly potent tool. So I fast a lot. I just finished a fast yesterday, actually. So I used to do a thing where I fasted seven days every quarter.

    8. EWEileen White1:02:11

       Oh, wow.

    9. PAPeter Attia1:02:11

       So four times a year, I would just do a water-only fast.

    10. EWEileen White1:02:14

        How hard is it to do that?

    11. PAPeter Attia1:02:17

        It is not that hard, I'm gonna be completely honest with you. I wish I could sit here and say, "Oh, I'm a real stud."

    12. EWEileen White1:02:23

        [laughs]

    13. PAPeter Attia1:02:23

        "Nobody can do it." No, no, anybody can do it. I really think anybody can do it. Which is not to say that there aren't moments throughout those fasts where it's sort of difficult, but you'd also be surprised at how resilient the body is. So yeah, not that hard. You have to make some adjustments. Obviously, you have to be very thoughtful about how much water you're drinking and how many electrolytes you supplement. There are a lot of changes that are happening in terms of electrolyte management and things like that. But again, we certainly have the knowledge to know how to manage people through that. But I began to ask the question, right, which is, okay, is seven days a quarter the right dose? I'm convinced that it's a big bolus of autophagy, but is it frequent enough? What about three days every month? That's about the same number of total days fasted, but it's more frequent, but it's probably less potent. And the reason I sort of decided to try three days a month was I noticed that a couple of things happened at the end of my fasts. So I always check my blood before and after one of these seven-day fasts, and there's a very predictable set of changes that occurs, some of them that are really obvious. Glucose plummets. Insulin becomes unmeasurable. Uric acid goes through the roof, along with beta-hydroxybutyrate, of course. Two possible explanations for the uric acid going through the roof. One is the breakdown of nucleic acid.

    14. EWEileen White1:03:42

        Mm.

    15. PAPeter Attia1:03:42

        And obviously-- and when I talk go through, I mean doubling of uric acid, so much so that I started taking allopurinol during a fast to make sure I didn't get gout.

    16. EWEileen White1:03:51

        Yeah.

    17. PAPeter Attia1:03:51

        Of course, it could also be, and I've read something that says that uric acid and BHB compete for the same transporter in the kidney, so there might also be a bit of a competitive blockade. But nevertheless, we have at least one possible explanation there. Endocrine function changes dramatically. T3 goes down significantly, and reverse T3 goes up significantly, such that the ratio of them changes by four to sixfold, which means you basically shut off metabolism. Not surprising. Explains why you become incredibly cold intolerant during a fast. And also, gonadotrophins go down. So you have all these really predictable things. But what I noticed was I see virtually all of them, though not quite to the same magnitude after three days, but not after two days. So that just got me intuitively thinking in a hand-waving way that three days was sort of the minimum dose you needed to really move the needle on a bunch of these other metabolic things, meaning the spike in uric acid, the bottoming out of glucose. So there's another thing that sort of happens. It's as you turn more and more free fatty acid into ketone and turn more glycerol into glucose, you reach an equilibrium where your glucose is pretty much gonna stay at about three to four millimolar, and that takes about two to three days. And again, when we think about it through the lens we've already discussed, AMPK must be up through the roof, mTOR must be through the floor, and protein deacetylation must be off. I think my gestalt is that that takes about three days, and obviously it gets greater and greater the, the more you go. But what would be amazing is if I could draw a tube of blood, send it to you after a three-day fast, a four-day fast, a five-day fast, a seven-day fast, a 10-day fast, and get some sort of quantification. What is it that we would see in-- Now, of course, it's complicated 'cause you'd probably want to accompany each of those tubes of blood with a muscle biopsy so that you could look at LC3, LC2, and things like that. So I'll stop on my diatribe for a moment and now turn it over to you, which is where would you even begin to look for that signature of autophagy? And let's just start broadly with any tissue. You can have blood, you can have muscle, you can have liver, you can have adipose tissue. How would you now create a dose effect?

    18. EWEileen White1:06:12

        Well, we know that what happens in a mouse-- Let's just take a minute to discuss that. So Mizushima lab made a, a mouse that had a transgenic LC3 EGFP protein expressed, and they could use that mouse-

    19. PAPeter Attia1:06:28

        Tell folks what LC3 is just so-- 'cause we're gonna talk about this quite a bit.

    20. EWEileen White1:06:31

        So LC3 is the protein that is attached to the autophagosome membrane and links to the cargo that ends up in the autophagosome.

    21. PAPeter Attia1:06:42

        So this is a very mechanical thing, right?

    22. EWEileen White1:06:44

        Yes.

    23. PAPeter Attia1:06:44

        Like, this goes back to your observation in the electron microscope.

    24. EWEileen White1:06:48

        Exactly right. So LC3 is one of the key proteins attached to the autophagosome membrane, and you use it to see autophagosomes because normally when autophagy is off, LC3 is diffuse. But when autophagosomes form, the LC3 protein is attached to them and you start to see spots where all the autophagosomes are present. And so the Mizushima lab used that to assess autophagy in a living mouse. They fasted the mouse and they found that they could see the formation of au- autophagosomes throughout the mouse.

    25. PAPeter Attia1:07:31

        And could they do this in like PBMC out of blood or do they need to use tissue?

    26. EWEileen White1:07:35

        They did it with tissue. What they learned was that, yes, autophagy is turned on during fasting in a mouse, which wasn't surprising, but it seemed to not be uniform across every tissue. So that was interesting. But we don't have a way to do that in people. All we can do-- 'cause this is involved making a genetically engineered mouse, so the only thing we can do in people would be to look at a tissue section and stain it for LC3 and then look to see if there were spots.

    27. PAPeter Attia1:08:09

        In other words, you could not look at LC3 conversion in white blood cells?

    28. EWEileen White1:08:14

        You could, but there's another problem in that you could take PBMCs and do a Western blot for LC3, and LC3 gets processed from LC3-I to II, and the II form is the one that's attached to the autophagosome membrane. So you could do a Western blot of PBMCs to measure the conversion of I to II, but then II ends up in the lysosome and gets degraded. So the typical measurement of au- autophagic flux involves measuring the rate at which LC3-I gets converted to LC3-II, and then the rate at which LC3-II ends up being degraded in the lysosome. And in order to see that flux, you need to block the degradation of LC3-II in the lysosome with Bafilomycin or Hydroxychloroquine. And so you would only be able-- by looking at LC3-I and II in PBMCs in a person that was fasting, you would only be able to infer autophagic flux because you wouldn't actually be able to measure it.

    29. PAPeter Attia1:09:29

        It's a clue.

    30. EWEileen White1:09:30

        It's a clue. It wouldn't be proof, but it would be one could presume, I would expect you would see more conversion of I to II and then II going into the lysosome. I don't think that would get you the answer that you need.
12. 1:13:00 – 1:22:15

    Current knowledge gaps around fasting as a tool for longevity

    1. PAPeter Attia1:13:01

       It's not going to be a regression model based on five things we know. It's going to be much more complicated.

    2. EWEileen White1:13:06

       And I prefer not the under the lamppost science.

    3. PAPeter Attia1:13:10

       Yeah, take an unbiased view and go-- And honestly, I get asked about this more than any other translational problem. So the good news is I think there are a lot of people in the philanthropic community that would be interested in this, even if this is not a question NIH is interested in. I doubt NIH is interested in this problem, although that strikes me as odd given how potent a tool fasting is and yet how we don't know how to dose it. And I think it's worth pausing on that for a moment because that is such a stark statement, if I'm correct. I believe I am. Which is, imagine we had the most amazing drug imaginable. Imagine we had a proteas inhibitor for HIV, and we knew deep down this could cure HIV. The problem is we didn't know how to dose it. How long would we tolerate that ignorance? Imagine we had a drug that we knew could kill cancer, but we just didn't know how much to give or how often to give it. We wouldn't tolerate that for a minute. And yet in fasting, we have arguably the most potent tool, and certainly if not the most potent, probably one of the three most potent tools in which we can affect human health, and we don't have a clue how to dose it or what frequency with which to use it. And I find that ridiculous. So I'm actually really confident that if there were a really great proposal put together that would go from the animal model to the human model, it would be fundable. It would be fully fundable through philanthropic efforts. And so if nothing else comes of this discussion, I, I would love to plant that seed with you and think about what would be the right consortium of people to do that work. Obviously, there are lots of skill sets that we'd want to have involved in there, but I really believe that could be funded quite easily. And I think that the implication of that is as potent as anything else. Because again, here I am doing my three-day fast every month versus my seven-day every quarter versus five-day every quarter. Like, we just don't know, and it really is troubling to me. It just drives me insane.

    4. EWEileen White1:15:17

       Well, I think for the general community, I think it's an important question even for practical reasons, because you may, you know, be able to control your life to the extent that you can do all this at your own convenience. But a lot of people don't have that flexibility. And so if they can be told that fasting for X amount of time is all you need to do, then the beneficial effects of fasting could be-- there would be more people that could take advantage of it.

    5. PAPeter Attia1:15:52

       Absolutely. And if you look at the work of someone like Valter Longo, who his assertion is you can get most of the benefit without actually having to be fully fasted, but to do something that is like a fast mimic, where you reduce your calories significantly for a period of five days. Again, maybe he's right, but we have no idea. We have no idea what the efficacy of that approach is versus a total water-only fast for five days. And it would be great to know because if we could demonstrate that you're getting eighty percent of the benefit doing a fast mimicking diet versus a complete fast, well, that opens the door to many more people who would be willing to do fast mimicry versus an outright fast. And again, I think about this constantly, which is I'm almost willing to do anything. I just want to know what to do.

    6. EWEileen White1:16:40

       So I think that now is the right time to ask that question. Let me just digress a little bit to talk about metabolism. So we know a lot about metabolism, essentially the field of not only just cancer metabolism, but metabolism in general, mapped out all the metabolic, well, most of the metabolic pathways. But what we lacked the ability to do until fairly recently was to have a thorough understanding of metabolism in a living mammal. And so Josh Rabinowitz and I have invested a lot of effort in developing technology to use isotope tracers. This would be C-thirteen labeled glucose and o- amino acids and so forth, and to deliver them to living mice running around and doing normal mice things in a cage, and then look to see how they're used and how different tissues use them and how there's nutrients sharing between tissues. Because when you're fasting, there's many complicated things going on. It's not just like there's no food and you're inducing autophagy and that's that.

    7. PAPeter Attia1:17:57

       That's the only thing that's happening in a vacuum, right.

    8. EWEileen White1:17:59

       [chuckles] So you have dedicated nutrient stores. You have glycogen in your liver that's mobilized, and that's dumping glucose into the bloodstream. You have fat adipose tissue that starts degrading your triglycerides, and then you end up with glycerol and fatty acids in the bloodstream, which then, you know, are taken up by the liver and so forth. So you have all these... You know, if you're really without nutrients for a long time, then your muscle proteins start being degraded, which is probably undesirable. That's dumping amino acids into the circulation so that you can maintain your survival. We have to understand all of that.

    9. PAPeter Attia1:18:41

       Because it really occurs in different phases. Again, if we just limit it to humans for a moment where we have a pretty good understanding of this, what's happening in the first twenty-four hours versus the next twenty-four hours versus the next twenty-four hours is very different. And George Cahill's famous fasting study, the forty-day fast on the healthy subjects, really divides it into these phases. What's interesting is by about seven days into a prolonged fast, you pretty much reach a steady state. You've got a pretty consistent flux of triglyceride into free fatty acid out of the fat cell. You reach a steady state level of beta-hydroxybutyrate, acetoacetate, and glucose, such that basically the sum total of them in millimolar concentrations is about preserved to where you would be non-fasting like. And so it begs the question, if we posit that once you reach that steady state of seven to 10 days, you're clearly in a fully turned on autophagy state, what's the switch look like? When you're 24 hours or 48 hours or 72 hours into that, are you 80% of the way to the benefit or just 20%? That's a jugular question.

    10. EWEileen White1:19:49

        Yes. I think it would be fascinating to understand that. And I think that if you look back over history, almost all cultures have fasting as part of their history. And I'm thinking that that is not by accident. I think they must have learned by trial and error that this was a healthy thing to do. And so I think that autophagy, I would expect, is playing a major role in promoting health in response to fasting. But I really think, well, maybe I'm sticking my neck out, but I think using fasting as opposed to trying to find some pill you could take is something that's easy to do.

    11. PAPeter Attia1:20:34

        And of course, it speaks to the irony of it, which is if you took probably 1% of the budget that is being dispensed to find pills that stimulate autophagy, we would actually be able to answer this question clearly.

    12. EWEileen White1:20:47

        Absolutely.

    13. PAPeter Attia1:20:48

        And actually just have a dose response. And look, that doesn't mean these things can't coexist. I'm all for it, and I wanted to ask you, of course, about some of the other pills like rapamycin and metformin and the role that they might have and how we might be able to measure that. But again, this just strikes me as the most obvious question in the space of how to prevent disease. And it's like you have this beautiful, beautiful tool, and you don't know what the dose is, and you don't know what the frequency is.

    14. EWEileen White1:21:18

        If someone knows that they're susceptible to a neurodegenerative disease, has anyone looked at those people to see if they engaged in some sort of fasting regimen, whether that was helpful or not?

    15. PAPeter Attia1:21:34

        Indirectly. I mean, it's possible that that's been done directly, and I just am not familiar with it. I think what we've seen indirectly is dietary restriction as opposed to just pure caloric restriction, where you improve the quality of macronutrients, specifically around improving glycemic control. You can take people that are in an early stage of cognitive impairment and delay it and/or reverse it through that type of nutritional intervention. Now, of course, that doesn't necessarily say autophagy is playing a role because that's doing a lot of other things. It's improving glucose and insulin signaling in the brain. It's doing a lot of other things, and we're really starting to see the impact of metabolism in the brain.

13. 1:22:15 – 1:32:50

    Rapamycin, metformin, and other molecules that may induce autophagy

    1. PAPeter Attia1:22:15

       So that's not entirely clear. Indirectly, I would say there are, I think, some pretty interesting compelling pilot data that suggests that rapamycin is neuroprotective. And again, rapamycin, a very potent inhibitor of mTOR, would presumably on some level induce autophagy. I think it's a very interesting question as to what is it about rapamycin that induces a longevity phenotype. Rapamycin to me is the most interesting molecule out there because it is, I think, the only molecule that has demonstrated a longevity benefit across all four models of eukaryotic cells. So that's a really big deal that can't be ignored. But how much of that benefit is through autophagy? I'd like to turn that question to you. How much of it is through inhibition of senescent cells, reduction of inflammation? Again, so it's very indirect and it speaks to, again, I don't mean to sound like a conspiracy theory guy because I'm not, but it is a little frustrating that we have these amazing tools, but because they're not particularly profitable, you don't really have somebody that's interested in answering them. And that's why I, again, come back to, A, I think these are answerable questions. B, I don't think they are billion-dollar questions. I think they are really questions that are amenable to the philanthropic community. And I think from an ROI perspective, it's hard to think of examples of where you could put dollars to work in research that would have a greater impact on human life.

    2. EWEileen White1:23:41

       Right. And I think that our biomedical community is mostly focused on putting out fires rather than disease prevention, although I've seen a change. I mean, I see at the NCI, the National Cancer Institute, a bigger interest in cancer prevention. So I think people are coming around to realizing that making people healthier longer is probably more important than once they discover to have stage four pancreatic cancer, what can we throw at it to make them live another two months?

    3. PAPeter Attia1:24:20

       Yeah. Again, it is sort of amazing to me how lopsided our resource allocation is with respect to that problem, because you're absolutely right. We have spent probably a quarter of a trillion dollars in the last 40 years on the second question, which is, once you have metastatic cancer, how do you live longer? And we've done an analysis on this. So for the quarter of a trillion dollars that has been spent on that problem, on average for solid organ tumors, we have extended median survival by less than about a year since 1970, so almost 50 years. That's pretty sad when you think about the fact that there's not much evidence we've reduced the arrival of cancer. In fact, all we've done is basically come up with a second leading cause of cancer in terms of modifiable behavior, which is after smoking, it becomes down to diabetes, insulin resistance, and all of the metabolic dysregulation. So yeah, I'll get off my soapbox now, but again, I, I-- this is in many ways just a, a sort of a plea for help, which is I think there's just an amazing opportunity to understand this.

    4. EWEileen White1:25:31

       So there's another component to this that worries me greatly. So what we've seen-- You know, so a lot of this, you're talking about controlling metabolism to preserve health through implementation of fasting and understanding fasting. But look what's happened to the American diet. I mean, there are people now that don't even recognize vegetables in the supermarket. There are people that only eat prepared food. And so what we've seen is, on the one hand, you're talking about preserving health and all that, but on the other hand, the overall health of Americans is deteriorating. Obesity is greatly increased and has no sign of, of abating. The diet of Americans loaded with high fructose corn syrup and diets that are disproportionate with prepared food. So the only way to globally improve the health of Americans, or anyone else for that matter, is to deal with both of these problems at the same time.

    5. PAPeter Attia1:26:45

       And to me, that's probably the greatest line of reasoning that says fasting is probably protective against all chronic disease. Because if you look at the three main chronic diseases that account for, to our last analysis, eighty-two percent of deaths above the age of fifty in the United States, excluding COPD, so if you take out the obvious smoking-related death of COPD, eighty-two percent of death is attributable to cardiovascular disease, cancer, Alzheimer's disease, and complications of diabetes. That's pretty stark. There's no question that when you improve metabolic health, which you can do through fasting, you reduce the risk of all of those significantly. Of course, the question becomes, how much of a role does autophagy play in that? Specifically, you look at the example you gave of neurodegeneration, that makes a very compelling case for it. Probably also in cancer. What, what do we know about cardiovascular disease, by the way?

    6. EWEileen White1:27:45

       Nothing comes to mind. I don't recall seeing anything in that area.

    7. PAPeter Attia1:27:50

       Yeah. I mean, my take on the literature is that the benefits of fasting in cardiovascular disease are primarily mediated through the metabolic health benefits of it. Lower glucose, lower insulin, lower homocysteine and time, lower inflammation primarily, as opposed to something that directly pertains to ApoB or the inflammatory response to that. But again, maybe it's just there and I haven't seen it. What else do you think is going on? What travels with autophagy? Can we talk about senescence for a moment? Do we understand a sense of what's happening when an animal or a human is undergoing autophagy with respect to either SASP or just the overall senescent cells?

    8. EWEileen White1:28:34

       Yeah. There seems to be complicated roles for autophagy and senescence. There's evidence from the Nerita lab that SASP, the secretion of inflammatory factors that occurs during senescence, is facilitated by autophagy. But then in the cancer setting, you-- there's also examples where loss of autophagy limits senescence. So I think in the senescence area, it's still a little bit confusing and maybe a little bit context dependent as to what's happening.

    9. PAPeter Attia1:29:11

       And then going back to the question about molecules, what do we know about metformin and autophagy? Do we know that in a fed state, if we give an animal or a human metformin, we can still induce autophagy all things equal through just the AMPK activation?

    10. EWEileen White1:29:28

        Yes. And I think that that's true, but I think that we don't understand over the long term what happens and what the consequence of having autophagy or not having autophagy is. So for example, we've never given metformin to our mice that don't have autophagy. That might be an interesting thing to do. What is the consequence of autophagy induction by metformin? It actually might be better to do that in a system where autophagy could be-- wasn't completely gone, but could be toggled up.

    11. PAPeter Attia1:30:07

        Do you have the ability to turn autophagy into an analog versus a digital, meaning where you can actually use gradations versus just on or off?

    12. EWEileen White1:30:17

        Yes. I think the mouse model where autophagy, expression of essential autophagy gene is controlled by an shRNA might be the way to do that experiment.

    13. PAPeter Attia1:30:29

        And then what about rapamycin? What do we know about the use of rapamycin, which has been studied so liberally across, again, everything from yeast, flies, worms, mammals, uniformly extends life, potent inhibitor of mTOR, which would signal autophagy all things equal. Where do we see that relationship?

    14. EWEileen White1:30:49

        So there's been a lot of discussion about using rapamycin or rapalogs as autophagy stimulators, but it's like you-- what you said before. It does many other things, and it's also immune suppressive.

    15. PAPeter Attia1:31:04

        Although that also depends on the dose, right? I mean, the-

    16. EWEileen White1:31:06

        True

    17. PAPeter Attia1:31:06

        ... the everolimus data suggested that it was actually immune enhancing when given intermittently.

    18. EWEileen White1:31:12

        Also have to remember that if you have a small molecule like rapamycin and you want to use it to preserve someone's health, you have to make sure that it's safe, and I think that's when everyone backs away. Because if you've got cancer and they want to try an experimental drug and you've got no other hope and you're gonna be dead in a short period of time, there's a bit of latitude in what can be done clinically to test whether or not there's a small molecule or some sort of drug that will be safe and possibly have efficacy. But when you're talking about prevention, it's a big problem. The drug companies are not interested in it because the amount of time it would take and the risk of-

    19. PAPeter Attia1:32:05

        Right, just a much narrower margin. By the way, that's exactly the reason we're in the situation we're in. So just to reiterate, we have a situation where I am not convinced that longevity as a game is going to be won on the back of extending the time you have a disease. I have never seen a shred of evidence to suggest that that is the answer. Everything in humans and animals points to the opposite end of the spectrum. Longevity is about delaying the time it takes until disease comes. The implication of that is prevention is the single most important tool in the longevity toolkit. How do we reconcile that with what you just said? All of our pharmacologic efforts, the trillion dollars we spend on drug development,

14. 1:32:50 – 1:36:45

    How to study fasting and exercise as longevity tools

    1. PAPeter Attia1:32:50

       is all on the wrong side of the equation. It's on the how do you live longer once you have a disease. And I understand why that's the case for all the reasons you just said, and if that doesn't make the most compelling case for taking the best and safest drug of them all, which is fasting, and understanding how to dose it and what frequency to dose it, I don't know what makes a better case. Along with exercise, by the way.

    2. EWEileen White1:33:14

       Yes, yeah, yeah.

    3. PAPeter Attia1:33:14

       I'd put the same-- I, I put exercise in that same category, which is it bothers me that we don't really know how to dose exercise either. I mean, it's less of a problem, I think, because for most people, the issue is do more, but it would be really nice to know what the dose response is on different types of exercise, especially for people who want to do the minimum effective amount. So both from an exercise perspective and a nutrient deprivation perspective, there's no more low-hanging fruit in terms of minimizing human suffering than understanding how these things work.

    4. EWEileen White1:33:47

       You should start a biotech company to do this. [chuckles]

    5. PAPeter Attia1:33:50

       David Sabatini and I have talked about this at length, and he has constantly told me to do this. And the way we've thought about it, it's not going to happen because I won't do it, [chuckles] so someone else will have to do it. The way David describes it very eloquently is right now, metabolic response to nutrients is a black box. And what David thinks, and I, I think he's right, is there's a multi-billion dollar opportunity in decoding the black box. In other words, when we understand exactly what the response is to each different type of nutrient in every different dose and frequency, and we can decode that in the way that we can do with so many other biochemical processes, you can do everything. 'Cause then you could actually develop drugs probably that could actually do something. So there's a drug development platform that comes out of that. And then from my standpoint, what I'm really interested in is, is simply just on the front lines as a sort of knuckle-dragging doctor, how do you even just put this into clinical practice? But again, it, it's high risk. It's a lot of effort to do part of that. I think on the drug development side, there's a lot there. I don't think it's very high risk on the question I posed to you earlier. I think the let's do the mouse study and identify the 50 metabolites proteomic signature things that are generally going up with autophagy, and then let's shotgun that in an unbiased way against human subjects. Like I feel like that's a project in the tens of millions of dollars, not even the hundreds of millions of dollars. And again, if you add one year of life to each human as a result of that, that's kind of staggering.

    6. EWEileen White1:35:25

       Right, and I think if you couple understanding mechanisms of metabolic delay of damaging diseases with surveillance for risk factors, I think those two things really need to be coupled together because you can-- even if you define what the optimal diet and exercise and fasting regimen is for delaying the onset of disease, there are still unlucky people. And I think that we can't forget about them in the context of health and longevity and well-being, because you could have the healthiest diet and do everything right-

    7. PAPeter Attia1:36:11

       Vogelstein has written about this, right? I mean, there's clearly a component. There's a stochastic-

    8. EWEileen White1:36:16

       Yeah

    9. PAPeter Attia1:36:16

       ... component to this. And yeah, so absolutely. And again, I don't think there's any reason to believe that we couldn't be addressing both of these.

    10. EWEileen White1:36:22

        Yes. Yeah, I mean, I think that there's no reason to do everything. One always has to bear in mind that there is this other risk factor that no matter what happens with understanding metabolism and fasting and good health practices, that other thing is still gonna be there. If you have a BRCA1 mutation, that's

15. 1:36:45 – 1:38:25

    The Nobel Prize for autophagic research

    1. EWEileen White1:36:45

       a compounding and separate issue.

    2. PAPeter Attia1:36:48

       So in 2016, the Nobel Prize was awarded for the basically the genetic elucidation of autophagy. What are the salient features of that award? What was it about Ohsumi's work that led to that award?

    3. EWEileen White1:37:01

       So what Ohsumi did was quite profound and very creative. He developed an assay-- Well, he asked what are the-- I mean, yeast requires nitrogen for survival, and he asked, "What are the genes that are required for nitrogen survival?" And he identified the autophagy, essential autophagy genes. And I always wondered whether if he was in the United States, would work like that be funded? Because it just seems like it was an important question, but-

    4. PAPeter Attia1:37:33

       It didn't have such a clear application down the line.

    5. EWEileen White1:37:37

       That's right.

    6. PAPeter Attia1:37:37

       Yeah, it was a bit too high risk to fund.

    7. EWEileen White1:37:40

       Right. And, you know, also the clear disease connection wasn't there, and so forth and so on, and nonetheless, he did that. And I guess the point is, is that sometimes scientific discoveries are so basic that you can't ever anticipate what it would ultimately lead to. And in this case, it led to something very extraordinary, but he probably had no idea at the time. And once they discovered these essential autophagy genes in yeast, then it was apparent that there were homologs in mammals and so forth and so on.

    8. PAPeter Attia1:38:16

       How conserved are those genes between yeast and mammals?

    9. EWEileen White1:38:19

       If you do a BLAST search, you can see them. I mean, not all of them, but

16. 1:38:25 – 1:49:25

    Eileen’s future areas of research

    1. EWEileen White1:38:25

       the amino acid homology was compelling.

    2. PAPeter Attia1:38:29

       Wow. So when you sort of think about the future of this, I think so much of what we've talked about kind of feeds into what your optimism is, but how do you want to spend the next 10 years of your career? What are the questions you want to probe?

    3. EWEileen White1:38:45

       I think I would like to translate what we've learned about the role of autophagy in cancer, and that involves developing small molecule inhibitors to inhibit autophagy for cancer therapy. And Alec Killiman and I started a company to do that, and what we're focusing on now is defining at the molecular level what the functional requirements for autophagy are in individual cancers. And this involves understanding the metabolic role of autophagy, why one cancer needs autophagy more than another, and then the newest connection is the connection to inflammation. When you inactivate autophagy, you stimulate inflammation, and this is what we've talked about earlier. In the context of cancer, that could be a really good thing because the game changer in cancer therapy now is immune checkpoint blockade.

    4. PAPeter Attia1:39:49

       Mm-hmm.

    5. EWEileen White1:39:49

       In fact, what I was just talking about at the ACR meeting yesterday was the particular patient that came to our cancer center and went through surgery, radiation, chemotherapy, and it all failed, and her body was riddled with tumors. And she went on a clinical trial for immune checkpoint blockade, and all her tumors melted away. And that was five years ago, and she's perfectly fine. So what we have to do is make that work for everybody. And if inhibiting autophagy activates the immune response and can facilitate not people who wouldn't respond to immune checkpoint blockade to respond, then that would be critically important to do.

    6. PAPeter Attia1:40:40

       I mean, let me think about that for a second. So when we think about the patients that are responsive, and we really have two big targets, right? CTLA-4 and PD-1. Melanoma obviously is a huge success story here because it is so mutagenic. It's interesting, I have a friend who has Lynch syndrome, so that's a familial syndrome where people are predisposed to cancer. He developed colon cancer when he was quite young, went on to develop pancreatic cancer, adenocarcinoma of the pancreas, which is uniformly fatal, almost without exception. He presented with an advanced state, so he was not even a surgical candidate. So the tumor had completely engulfed his mesenteric artery and vein, which meant he couldn't even undergo the surgical procedure, though it wouldn't have done much anyway. I had just read a paper six months earlier in The New England Journal of Medicine about... I forget what the paper was exactly about, but it made me think that because he had Lynch syndrome and he has so many mutations, he might be a candidate for a checkpoint inhibitor. So we went back to his oncologist and said, "Hey, can we get him on Keytruda?" They said, which is an anti PD-1, they said, "No, [chuckles] that's, there's no standard for that." But we found a clinical trial, actually got him in. He got Keytruda. That was five years ago. He's disease free. So you go from unresectable pancreatic adenocarcinoma to no pancreatic cancer, pretty remarkable. Now the question is, when I think about how broadly extendable that's going to be, it really comes down to how many shots on goal do you get? How many mutations do you get such that you can activate these checkpoint inhibitors? And so tell me how autophagy fits into that, 'cause I think I'm missing the link of why enhanced immune, nonspecific immune response would factor into that. I, I know there's a link, but I'm, I need you to explain it to me.

    7. EWEileen White1:42:39

       So that's exactly where we're going with our, our research, and should have heard about me. [laughs]

    8. PAPeter Attia1:42:43

       I should have been at the ARC yesterday. Yeah.

    9. EWEileen White1:42:46

       So we know that tumors with a very high mutation burden respond better to immune checkpoint blockade. But it's not that simple because there are patients with tumors that do have a high mutation burden that don't respond, and we don't know why. It could be they've upregulated some other checkpoint that we can't yet inhibit, or it could be some other reason they don't express class one or that the immune system can't see the tumor for some various reasons. And then we also know there are tumors that have a low mutation burden that do respond.

    10. PAPeter Attia1:43:20

        That do respond, yeah.

    11. EWEileen White1:43:21

        And so a big part, in fact, we just got an NIH grant to study this, is to make- Mouse models of cancer with low, medium, and high mutation burden with which to study-

    12. PAPeter Attia1:43:36

        And then you can bang out autophagy and-

    13. EWEileen White1:43:39

        Exactly. We haven't done the autophagy part yet. We're just doing the generating the models using proofreading mutations and polymerase epsilon and delta to generate mice with cancer with various levels of mutation burden in their tumors. And this is so cool because we'll be able to ask basic questions like, "How many mutations do you need?" When you have a low mutation burden, what can you do to make the immune system see that tumor? Do you need only mutations in the nuclear genome? What about mutations in the mitochondrial genome? So one of the mouse models we made was to generate a mutator phenotype in the mitochondrial genome. There are human cancers that have a high level of mitochondrial genome mutations. Whether that has any effect on anything is completely unknown. There's no reason why they couldn't be presented as tumor antigens.

    14. PAPeter Attia1:44:42

        And you'd think, if anything, they would be more immunogenic. I mean, they should be, all things equal, just because of their bacterial origin. That should elicit a much greater immune response.

    15. EWEileen White1:44:52

        Exactly right. This is what this grant is designed to do, to generate mutator phenotypes in mouse models of cancer so we can have a spectrum from low to really high mutations in the nuclear genome as well as the mitochondrial genome, then to figure out the mechanism of response to immune checkpoint blockade to make cold tumors hot. And that's essentially what the loss of autophagy is doing by promoting inflammation. It's taking a tumor that is not killed by T cells, that does not respond to immune checkpoint blockade, and rendering that tumor responsive.

    16. PAPeter Attia1:45:31

        And where do you put this on the hierarchy of optimism for the future of cancer therapy? I mean, to me, the interesting stuff in cancer therapy is getting more and more targeted and stacking more and more therapies on top of each other. So this is an elegant example of stacking something that is clearly going to become a pillar of oncology, which is immune-based therapy, with something that frankly is partially metabolic and frankly partially more complicated than just metabolic therapy. So you've got-- You almost add this to the layer of pieces of Swiss cheese you start to stack on top. If you have enough of them, you're not gonna be able to drop a pencil through. The cancer doesn't survive.

    17. EWEileen White1:46:10

        That's right. So one of the limitations that we have with immune checkpoint blockade is, some of which I've already mentioned, we can't identify who's gonna respond and who's not gonna respond, and we have to extend the responder pool. But we have to be able to model that because it's very clear that a single agent, so it's gonna be a, immune checkpoint blockade therapy, is not gonna help most of the patients. So how do we go about optimizing this treatment and having models where you can combine immune checkpoint blockade with other therapies to evaluate what is the optimal response is critical, and that's what we're doing. And whether fasting influences this is completely unknown.

    18. PAPeter Attia1:47:03

        What's the role of autophagy in the immune cell itself? So either adaptive or innate, I mean, maybe both.

    19. EWEileen White1:47:10

        Right. So we know that one of the things we did was to turn autophagy off in a mouse and ask how that affected basic immune responses. And the answer was everything in the short term appeared to be completely functional. And if anything, the T cells were more antitumorigenic. But if you go into the long term, if you knock out an essential autophagy gene only in T cells, for example, and look nine months later, I think those T cells are not gonna be very functional. But it, it really depends on how you design the experiment. For cancer therapy, we wanna know what happens acutely. When you're inhibiting autophagy, you're going to be looking at things in the short term, not in the long term. So there's still a lot we need to do in that area. But in the short term for cancer therapy, the immune system seems to function well, if not better, in the presence of autophagy inhibition.

    20. PAPeter Attia1:48:24

        This just doesn't stop getting confusing because, again, you would think that given the benefits of autophagy in preventing cancer, one of them-- you would think that that would only enhance innate immunity because of the role innate immunity plays in cancer screening, which again, I think just speaks to we are still really scratching the surface of all of the different tentacles that come out of these tools. Something like fasting seems very simple, and it's simple, of course, to do, but it has such a set of pleiotropic extensions and benefits that it's very unlikely that it's about all or none. There's nothing black and white here. It's really all these shades of gray that it's not intuitive when you look at them what the net effect is because it's a little bit of this, a little bit of that, more of this than that. It's the balance of this versus that.

    21. EWEileen White1:49:23

        Yes, I would agree, and I think

17. 1:49:25 – 1:51:30

    A fasting strategy for Alzheimer’s disease prevention

    1. EWEileen White1:49:25

       context is important too.

    2. PAPeter Attia1:49:27

       When you think of all the big chronic diseases, just based on what you've talked with us today about, I, I think we have to be really excited about Alzheimer's disease based on the model you've shared. I mean, that strikes me as an amazing opportunity because one, we don't have a single tool. Once somebody has Alzheimer's disease, I'm sure you saw the most recent-- I don't know if you follow that literature, but we just saw two enormous failures in the anti-amyloid beta drug trials. So we're back to kind of square one, which is not a single drug that works for this condition. If any disease demands prevention, it has to be this one. It's hard to make the case that fasting isn't going to play a beneficial role there, isn't it?

    3. EWEileen White1:50:11

       I believe you. I'd love to-

    4. PAPeter Attia1:50:13

       We have to test this now. Yeah.

    5. EWEileen White1:50:14

       Yes, we have to test-- it has to be tested. But I think that when you look at the dramatic failures in preventing or delaying Alzheimer's disease, you have to ask the question, what is the root cause of that? And if you look at the approaches, all the approaches are designed to ameliorate a symptom, and the research has not yet gotten to the root cause. And I think that that is the reason for these spectacular failures, is they're trying to treat a symptom of the disease rather than the cause of the disease. And when you look at the genes that are involved in neurodegeneration in general, they fall into a broad array of different categories. And so my thinking is that they're all doing different things, but there's some common denominator that has yet to be identified. And I think that until the root cause of disease is identified, just finding means to ameliorate the symptoms is not going to be productive.

18. 1:51:30 – 1:58:54

    Future study of metabolism and autophagy

    1. PAPeter Attia1:51:31

       Eileen, you know, I could sit here and talk about this for hours and hours. I want to be respectful of your time because I know you've stayed an extra day to have this discussion with me, which I really appreciate. Is there anything else you want to talk about today, either as it pertains to your work, something you're excited about in the future, or anything else that pertains to autophagy?

    2. EWEileen White1:51:50

       I mean, I think that understanding in greater detail how autophagy impacts metabolism, we've done some of that, but I think there's way more to do. We have the technical ability to examine metabolic flux in a mouse in vivo in normal and starvation conditions and in response to different diseases, and we're only at the beginning of doing that. And I think that that's something that we will continue to do and hope that we can identify new targets for anti-cancer therapy or signatures of metabolic problems, and we will continue to do that. But again, I want to return to the immunotherapy. I think in the field of cancer, building on that huge gain, we can't take our eyes off that ball.

    3. PAPeter Attia1:52:49

       Those are both very interesting. And of course, the former, it sounds like you really agree with David Sabatini, which is there's an enormous opportunity to decode metabolism in a way that we should have done twenty years ago.

    4. EWEileen White1:53:01

       I think we lacked the technology. I mean, I think that-- So maybe I could take a minute to explain what we do in that by using C-thirteen or N-fifteen labeled tracers, you can put them into a mouse, infuse a mouse with these tracers, and by looking at where they go by mass spectrometry-

    5. PAPeter Attia1:53:26

       Over different time points

    6. EWEileen White1:53:26

       ... over different time points, you can see metabolism. And that was something that was never possible before.

    7. PAPeter Attia1:53:34

       What is it-- 'Cause we've been able to label these things forever. What was it, the mass spec didn't have the resolution before? Or what is it that-- Why is it we couldn't do this twenty years ago, I guess?

    8. EWEileen White1:53:43

       I think they could do it with radioactive material, and they could do it somewhat with the technology they had way back when. But I think that the technology now is far more sophisticated. By using heavy isotopes, you don't need radioactivity. Now there are more mouse models of disease. You could even do this in humans. So Ralph DeBerardinis at UT Southwestern is infusing these isotope tracers into humans with cancer and actually measuring the metabolism of human tumors.

    9. PAPeter Attia1:54:17

       Wow, that's interesting. I did an experiment once on myself with doubly labeled water, which of course is a very simple version of doing that sort of thing to examine energy expenditure. I had a field day doing that.

    10. EWEileen White1:54:28

        Wow.

    11. PAPeter Attia1:54:28

        [chuckles]

    12. EWEileen White1:54:30

        Yeah, but I think that, in fact, next week I'm supposed to go to a keystone tumor metabolism meeting where all the experts in this area will get together and talk about this in detail. But this is a growing field. It's very exciting, and understanding metabolism in mammals at a level we've never seen before in various disease states is tremendous.

    13. PAPeter Attia1:54:58

        And then lastly, is it safe to say that should there be a strong enough public demand and a philanthropic demand to go after that question we talked about earlier, about sort of decoding the dose effect of fasting, is that the sort of thing you'd be interested in working on?

    14. EWEileen White1:55:13

        Yes. I was fascinated by what happened when mice didn't have autophagy, and they died when they were fasted. And I am very much interested in fasting as a, a way to preserve health. I'm also interested in, as I mentioned earlier, the dietary part because I think all of this has to go together. It's not just how many calories you eat or how often you eat them. It's what they are. So yes, that's something that's very important to me.

    15. PAPeter Attia1:55:44

        Well, Eileen, thank you very much. This was super, super interesting, and I know that folks are going to... This will probably pose a few more questions than, than even we had time to go into, but that's great. Your work is fantastic, and I appreciate your generosity.

    16. EWEileen White1:55:58

        Oh, this has been a lot of fun. I'm glad I took the time to do this.

    17. PAPeter Attia1:56:02

        Thanks. Thank you for listening to this week's episode of The Drive. If you're interested in diving deeper into any topics we discuss, we've created a membership program that allows us to bring you more in-depth, exclusive content without relying on paid ads. It's our goal to ensure members get back much more than the price of the subscription. Now, to that end, membership benefits include a bunch of things. One, totally kickass comprehensive podcast show notes that detail every topic, paper, person, thing we discuss on each episode. The word on the street is nobody's show notes rival these. Monthly AMA episodes or Ask Me Anything episodes, hearing these episodes completely. Access to our private podcast feed that allows you to hear everything without having to listen to spiels like this. The Qualies, which are a super short podcast, typically less than five minutes, that we release every Tuesday through Friday, highlighting the best questions, topics, and tactics discussed on previous episodes of The Drive. This is a great way to catch up on previous episodes without having to go back and necessarily listen to every one. Steep discounts on products that I believe in, but for which I'm not getting paid to endorse. And a whole bunch of other benefits that we continue to trickle in as time goes on. If you want to learn more and access these member-only benefits, you can head over to peterattiamd.com/subscribe. You can find me on Twitter, Instagram, and Facebook, all with the ID PeterAttiaMD. You can also leave us a review on Apple Podcasts or whatever podcast player you listen on. This podcast is for general informational purposes only and does not constitute the practice of medicine, nursing, or other professional healthcare services, including the giving of medical advice. No doctor-patient relationship is formed. The use of this information and the materials linked to this podcast is at the user's own risk. The content on this podcast is not intended to be a substitute for professional medical advice, diagnosis, or treatment. Users should not disregard or delay in obtaining medical advice from any medical condition they have, and they should seek the assistance of their healthcare professionals for any such conditions. Finally, I take conflicts of interest very seriously. For all of my disclosures and the companies I invest in or advise, please visit peterattiamd.com/about, where I keep an up-to-date and active list of such companies. [outro music]

Episode duration: 1:58:54