Immune
With Vincent Racaniello, Cindy Leifer, and Stephanie Langel
Episode 4: Putting the immunotherapy CAR T before the cancer
Immune 4: Putting the immunotherapy CAR T before the cancer
Aired January 23, 2018
Transcribed by Kim Barker
Content on Immune (microbe.tv/immune) is licensed under a Creative Commons Attribution 3.0 License.
{Music}
VINCENT: From Microbe TV, this is Immune, Episode number 4 recorded on January 23, 2018.
{Music}
VINCENT: Hi everybody, I’m Vincent Racaniello, and you’re listening to the podcast about the body’s defenders against disease. Joining me today from Ithaca NY, Cindy Leifer.
CINDY: Hi! Welcome everyone, welcome back. This is great.
VINCENT: 2018!
CINDY: Yeah, I can’t believe it’s 2018 already. And we were a little delayed here and it’s almost the end of January already, getting this podcast going in January but looking forward to an exciting year of Immune this year.
VINCENT: From Wooster, Ohio, Stephanie Langel.
STEPH: Hey now, happy to be podcasting from Ohio. I’m gonna introduce a little weather, I know the other podcasts do that but it’s about 38 degrees here so the snow melted this weekend but it’s still pretty darn cold so. Little cloudy, but happy to be back in 2018.
VINCENT: Happy 2018 both of you.
STEPH: Absolutely.
CINDY: Yeah, same to you.
VINCENT: First Immune and we’re looking forward to 12 Immunes this year right?
STEPH: Woohoo!
CINDY: Alright. Plus maybe some one on ones in there.
VINCENT: Maybe.
STEPH: Yeah.
VINCENT: So it has been really cold I guess, everywhere for awhile.
STEPH: Yeah.
VINCENT: And it’s just warmed up today, it’s raining actually here, it’s 16 Celsius. So I think…
CINDY: Oh you’re warmer, we’re 9 here.
VINCENT: I think it’s gonna get cold again, which is fine because it is January right?
STEPH: Right. To be expected.
CINDY: It is.
VINCENT: Yeah, well that’s the way it goes. Well I’m looking forward to today’s episode. We don’t have a paper but we do have a topic.
CINDY: Yes.
VINCENT: And Cindy was brave enough to put all these great notes in here.
STEPH: Yes thank-you Cindy, it’s a big topic, but it’s quite exciting.
VINCENT: So Cindy don’t be dismayed if we interrupt you a lot, we just might.
CINDY: I think you should, because I did put a lot in here and I’ll tell you sort of what I’m hoping to cover. And so for those of you who didn’t catch it from the title, we’re gonna today talk about CAR T cells, or chimeric antigen receptor T cells. And this is something we’ve mentioned a couple of different times on the podcast and people have anxiously been writing e-mails to us saying when are you actually going to cover it? And so here it is today. And so CAR T cells are a type of cancer immunotherapy. And I thought one of the things I wanted to do was briefly introduce what immunotherapy is, and a couple of the developments that happened over time that got us to this point to these CAR T cells and then exactly what are they? And they’re this amazing sci-fi completely synthetic engineered thing that we’ve done based on what we know about the immune system. And it’s actually spectacular that we could do this and then it actually works. But to understand what it is, I think we need to tell the listeners a little bit about T cells and B cells. So once we have this little introductory part we’ll do a little primer on T cells and B cells. And then we’ll really get into the nitty gritty about how you make these things, how the therapy works, and I thought it would be cool to talk about some of the newer tweaks that have happened on this; because there’s the basic CAR T cells and then there’s a whole bunch of different things that people have done on this. And then I’m hoping to come back around at the end and sort of introduce the idea that people are taking this outside of the realm of cancer now. And then maybe some, a little bit on some of the negatives, because it’s all gonna sound really fantastic, that this is gonna cure, cure everything as we go through here. So that was sort of the overall goal of what I had for today. And so, starting with just basically what cancer immunotherapy is, it’s really the holy grail of oncologists. And of course an oncologist is a doctor that treats people with cancer. And so the idea is how can we harness our immune system and turn it against tumors? And for a long time people thought that you couldn’t do this. So, cancers are part of our own body, they’re just malfunctioning cells and they’re growing independently of their signals. And it was thought for a long time that our immune system couldn’t actually see them, because our immune system is designed to to see foreign things and to not react to things that are self, or you know, of our own origin. And so it was thought that we couldn’t see tumors. But there was hints of it over many many years, and a few experiments that people did that really showed that we could in fact have our immune system attack cancer, but it just doesn’t do it all the time. And so understanding why can’t it do it all the time and how could we massage or or re-direct the immune system actually against the tumors was really where people were. And so if you think about basically everyone knows someone who has had cancer. And if you think about the main treatment for cancer, it is extremely non-specific and designed to just kill any cells that are growing fast in the body. And so this is the chemotherapy; you put a lot of drugs in or you put radiation on the patient and you’re gonna kill anything that’s growing fast. But the the downside of that is that chemotherapy is gonna target those fast growing cells and they’re not just tumor cells. So there are a lot of tissues like hair and skin and intestine that turnover quite rapidly, and so they’re really dramatically affected with this chemotherapy or radiation. And so, what we really wanted to do is say how could we get more specific? How can you find the tumor and not attack all of these other normal cells? So that’s really been always the holy grail of this cancer immunotherapy.
VINCENT: The problem with chemo is that it would go into your vein and hit everything right?
STEPH: Right.
CINDY: Correct, yeah.
VINCENT: And you couldn’t, you couldn’t direct it at a tumor.
CINDY: Right.
STEPH: And I think what patients are really coming up with is this decision of do I want a longer life with lower quality of life or maybe a shorter life where I can actually enjoy my time with my family, and it’s nice to see that maybe there’s some other options out there.
VINCENT: Yeah. The other issue of course besides non-specificity is that you get resistance often very quickly to certain agents right? Within months?
CINDY: Yes.
VINCENT: And then you have no recourse.
CINDY: You don’t.
VINCENT: I remember my dad was being treated for colon cancer with 5 fluorouracil in the 80s.
CINDY: Yes.
VINCENT: So initially had this great regression, the tumor went away, and the next week it was back and the guy said don’t come back anymore, there’s nothing I can do you know?
CINDY: Wow, yeah yeah.
VINCENT: Can you imagine how that feels? Right, as a patient?
STEPH: Ugh, I don’t know…
VINCENT: Especially, you spent your life going to doctors and hopefully being treated and so forth and then: go home. Yeah that was pretty sad. So hopefully we can improve on that.
CINDY: Yeah, and so I guess one of the original improvements was kind of the directed radiation, so you could go and direct it right into the tumor.
VINCENT: Mmhmm.
CINDY: And so that helped things. And so I guess really when the first iteration of immunotherapy as we know it was to develop monoclonal antibodies.
VINCENT: By the way there’s a great history of chemotherapy in The Emperor of All Maladies. Have you read that? Both of you?
CINDY: I have not.
STEPH: I haven’t, but I’ve heard you talk about it.
VINCENT: Oh you should read it! It’s by Siddhartha Mukherjee who’s an oncologist here, he won the Pulitzer Prize for it. It’s a wonderfully written book, and he’s got a great history of chemo and how it went through different stages and, you know in the end, as you say, it’s still not great. But it brings, I think it comes up to monoclonals pretty much in that.
STEPH: I’ll keep a short list of the books we recommend, and maybe we can keep a running list.
CINDY: And in all our free time that we have…
VINCENT: Yeah, right.
CINDY: When we’re not…
STEPH: Podcasting.
CINDY: …working we can read.
VINCENT: So, Cindy, when did monoclonal technology come-what decade that they could start thinking about this- do you roughly know?
CINDY: I don’t remember.
VINCENT: It’s gotta be 70s right?
CINDY: I think so…
STEPH: I was gonna say 70s, because T cell engineering was the 90s, so it had to be like 70s or early 80s?
VINCENT: Let’s see…monoclonal antibodies…who invented monoclonal antibodies? 1975, Milstein and Köhler, right?
CINDY: There you go. Yeah, I knew they won the Nobel Prize for that yeah.
VINCENT: 1984 Nobel Prize Yep. So 70s.
CINDY: There you go.
VINCENT: And then once that came out people immediately probably started thinking how could we make these against tumors right?
CINDY: Exactly. And so if we can identify proteins that are expressed on the surface of a tumor, preferentially, or preferably exclusively, now you can develop an antibody that would target those cells. And some of the ways that is done is let the immune system recognize those tumor cells that now have antibody on them and let them attack it; so there’s something called antibody-dependent cell cytotoxicity where different immune cells can recognize the cells that are coated with antibody and kill them. And the other way you can do it is you can tag a drug onto the antibody, and that way you’re preferentially delivering the drug where you want it. So you can, like you were saying Vincent where you can inject into a vein and it’ll go everywhere, but then the antibodies will concentrate in the tumor and so they’ll concentrate the drug in the tumor. So that’s one way it was done. And one drug that’s been used that’s this monoclonal antibody against tumors, and that’ll become important is something called Rituximab. And it’s targeting a protein on the surface of a B cell called CD19. And so the idea here is you inject a patient that has a B cell tumor and the antibody will bind to the B cells, the immune system will attack those B cells and kill them, thereby killing the tumor. So that was really the first iteration of what immunotherapy was. And in fact, my Dad was treated with Rituximab, he had lymphoma.
STEPH: Oh really?
CINDY: Yeah, a number of years ago. He didn’t survive. But yeah, he was treated with Rituximab and it was a Non-Hodgkin’s lymphoma. Yeah
VINCENT: To tell the truth, we should point out that these “tumor-specific” proteins are actually not, they’re…
CINDY: Exactly.
STEPH: Right.
VINCENT: …they’re normal self proteins that happen to be, in this case on a B cell right?
CINDY: Yes.
VINCENT: But there really isn’t anything unique on a tumor that we could target, right?
CINDY: Occasionally there are antigens that get upregulated on a tumor that are not expressed in a normal adult.
VINCENT: Mmhmm, okay.
CINDY: So you could target them.
VINCENT: And they’re still, but they’re still recognized as self, right?
CINDY: Uh, yes.
VINCENT: So you’d have to put in, you’d have to infuse a monoclonal or do something, cause our own…
CINDY: Yes.
VINCENT: …system’s not gonna recognize it yeah.
CINDY: That’s right.
STEPH: And I think one of the kind of leading things that the field is looking at is using this next generation sequencing technology to think about the fact, OK cancer is a mutagenic event, there has to be, let’s find those neo-antigens or the antigens that aren’t expressed on self, and so taking solid tumors, metastatic tumors, and trying to delineate what is special about those tumors and then use the technologies that we’re talking about now to direct those. Because right, a pan-B cell marker like CD19 or a marker that’s expressed on all B cells really can cause problems in addition to the good of removing a B cell malignancy.
VINCENT: Yeah.
CINDY: That’s right. The catch is it has to be something on the surface of a cell.
STEPH: Right, right.
CINDY: At least for the type of therapy that we’re gonna talk about as well as monoclonal antibody therapy or anything involving B cell recognition, you require that to be on the surface. Yeah. So, this was, so this was great. You had a way to try and preferentially target things into a tumor like a drug or this antibody cell cytotoxicity, but then we started thinking about, well you know, what is it about the tumor that the immune system isn’t able to kill the tumor? And it turns out that the tumor is immunosuppressive. And so, the tumor’s really clever this way. It expresses molecules that shut down the immune system. So if a, if a T cell is revved up and ready to go and to kill the tumor, it gets there and gets this silencing signal from the tumor.
VINCENT: How could our bodies, how could our bodies deceive us like that? It’s our own cells!
CINDY: It is!
STEPH: Right. It’s not even a pathogen!
CINDY: And our immune system is…yeah, our immune system is designed to do this. So we think about the on signals for the immune system all the time. But we rarely think about the off signals. And there are a lot of them. I mean, we have to control the immune responses we have, otherwise you’d have a lot of pathology. And in fact the pathology can often be worse than the disease. That happens a lot with viruses, right? The viruses go in and it’s actually the immune system attacking the virally infected cells that cause more trouble than the virus itself sometimes. So it, you know we have these ways to regulate the immune system. And so what the the cancer has done basically is take advantage of that, somehow they figured out, well if I put this molecule up on the surface of the tumor cell, now the immune system when they come in they’re shut off and can’t kill me. So, so this led to this idea of checkpoint inhibitors. And so this was, this has been for a number of years now a buzzword and huge thing in immunotherapy. And so these are mechanisms to treat with antibodies that target these molecules that normally shut off the T cells. And basically you interfere with the T cell getting the signal from the tumor. And so if you block this T cell getting this signal from the tumor, the T cell can maintain its ability to kill the tumor and when it enters the tumor it can, it eliminates the tumor cells. And so these are things that are called checkpoint inhibitors. And they have crazy names and they target two main molecules on the surface of T cells that are normally important for shutting down T cell responses, and these are called CTLA4 and PD-1. If you, if you follow the nomenclature there.
VINCENT: Yeah so their discovery was huge, right?
CINDY: It was huge, really huge.
VINCENT: Cause that immediately was thought to be a way to drive this kind of therapy right?
CINDY: Absolutely.
VINCENT: So are these two the main checkpoint inhibitors or are there others?
CINDY: As far as I know, I think they’re the two main ones that are out there right now.
VINCENT: So basically they’re receptors on a T cell- the ligand would be turned up on the surface of a tumor, right?
STEPH: Correct.
VINCENT: And when that tumor interacted with a T cell then it would shut off the T cell’s…
CINDY: Right.
VINCENT: …ability to kill it, right?
CINDY: Right. So if you add these antibodies that will bind to this molecule on the T cell, it prevents the T cell from interacting with this signal it’s getting, it would normally get from the tumor.
VINCENT: And these are…are these checkpoint inhibitors approved now? I believe they are right?
CINDY: Oh yes, yes. So the first one was approved in 2011, and the second one was approved in 2014. So these have been on the market for a number of years now.
VINCENT: I see ads for them all the time.
CINDY: Absolutely.
VINCENT: And I think Jimmy Carter was treated with one of these, right?
CINDY: Yes, yes he was.
VINCENT: Yeah there’s, there’s one from Merck I keep seeing, what is that called…
CINDY: Yervoy? Is that the one? I’m not sure.
VINCENT: Let’s see…searching for…K something.
STEPH: K…K something it’s like Ketuba…Keytruda…
CINDY: Keytruda?
VINCENT: Keytruda!
STEPH: Keytruda yeah, it’s a lung, I think it’s a…
VINCENT: It’s Keytruda, yeah.
STEPH: …mesothelial…
VINCENT: Checkpoint inhibitor. Yeah I think they were…they…
STEPH: It’s a PD-1…
VINCENT: Pfizer were the first one to get these approved, right.
CINDY: Yeah.
STEPH: I think, some of the things that after the approval and actually seeing a lot of patients not respond at all to checkpoint inhibitors, basically finding maybe 20%…you could maybe have an increase in a population from 20% to 30% of people who had a decrease in tumors but there’s this huge population of people that just don’t respond at all. And that could be because reasons Cindy mentioned; the tumor microenvironment does not even allow the T cells to get there. So if there are not…there are not any T cells there, there’s not anything to take the checkpoint off of.
VINCENT: Yeah. Yeah.
STEPH: So I think that’s what also really led to trying to find other ways and other therapies like the CAR-T cells to try to get at this another way.
VINCENT: So Keytruda is Pembrolizumab, the monoclonal you mentioned.
CINDY: Yeah, so that’s the PD-1.
VINCENT: Yeah.
CINDY: Right.
VINCENT: So that can obviously work in some cases. As long as there are T cells around and you can get the monoclonal…
CINDY: Right. Right.
VINCENT: …at the tumor, right? Because some tumors are not gonna be accessible.
CINDY: That’s right. That’s right. And so one of the other immunotherapies that was also used for awhile was trying to isolate the tumor infiltrating lymphocytes, or the T cells directly from the tumor and grow them up ex vivo and then put them back in. And so this was without any of these other you know, targeting mechanisms or realizing necessarily that the T cells, once they got put back in were gonna get shut down or be unable to get to the tumor. But the idea was there that we knew there were T cells in the tumors, you could take them out, you could put them back, and we had these ideas that these tumors had these breaks or we could target the tumors with antibodies. So people started thinking about how could we sort of put all of these things together? And so that’s…and then I guess people got in a room and had some crazy ideas and maybe…you know, who knows what they were drinking or whatever, and they came up with these crazy idea, well why don’t we just redirect these T cells in a completely novel way?
VINCENT: So these efforts to pull T cells out of tumors, it didn’t work very well I guess, right?
CINDY: It, I mean it worked to some extent, but I mean, it was semi-predictable. The T cells were there in the tumor, but once you made more of them ex vivo and put them back, they didn’t all make it in the tumor and when they got in the tumor they got shut down.
VINCENT: Yeah, right.
STEPH: Because they had…
CINDY: So, yeah. So so there was there was that whole thing. But the idea was there that you know, if you could get the T cell in and if it didn’t get the shutting down signals and if it had some way to specifically recognize the tumor, there was the potential to to get these T cells to kill these tumor cells.
VINCENT: Mmhmm. And it’s T cells that we want right? That’s the one that’s gonna get rid of the tumor.
CINDY: Right. So there’s only two…there’s two main cell types in the body that have this capacity to go and kill a tumor cell. One is an NK cell and one is a T cell. And they kill by the same mechanism.
STEPH: An NK cell, for anyone who might not know, is just natural killer cell, so quite like its name, it kills things.
CINDY: Yeah. Right. And and to be honest, I I think you know, there’s people who study NK cells for a living for a very long time. But the reality is I think we know quite a bit more about the T cells and how they signal and how to to control them. And so people’ve gone after the T cells this way. So so the idea was here we’ve got antibodies that can target tumors, and they’re extremely high affinity. And they’re great at recognizing these antigens. But they’re soluble, and even if they were on the surface of a B cell, which sometimes they are, and we can talk about that later at some point…but even then, the B cells don’t have the capacity to kill the tumor.
STEPH: Right.
CINDY: So you’ve got these antibodies. And you’ve got these T cells that are great! They have all of these things inside of them that they can deploy and they can kill these tumor cells, but they really suck at recognizing the tumor. And so, is there a way to kind of smoosh these things together? And I…and so, what people came up with was well why don’t we take part of the antibody and put it on the T cell and make that recognize the tumor? And so if our listeners remember back to the paper we did last month on Zika virus, they made these antibodies that were small chain and bispecific and things, and so they had these ways to clone the specific region of an antibody that recognizes an antigen. And so we have this capacity to clone these fragments and then fuse them. And so we said well why don’t we just make the T cell receptor, instead of recognizing antigen the way it normally does, why don’t we make it recognize antigen the way an antibody does? So they take the fragment of what the antibody’s recognizing- the way it recognizes the antigen, this fragment of the antibody-and fuse it to the T cell receptor. And then put that back in the T cells and put them back into the patient.
VINCENT: So maybe you could tell us about T cell receptors.
CINDY: Yes. So…yes. So…this is where we have to get a little technical, so if your eyes bug out, just bear with us a little bit. So…
STEPH: We’ll come back around at the end.
CINDY: Yeah. So here’s the primer on T cells to be able to understand exactly how all this works. So we have two types of T cells; we have CD4 T cells and CD8 T cells. And what we’re really talking about are CD8 T cells. And so when we talk about CD4, CD8, CD19, what these are are CD stands for cluster of differentiation. And what that means is many years ago, before we had all the ability to know the DNA sequences and RNA sequences of all of these genes, what we had were the ability to inject these things into animals, isolate out the antibodies that recognized these, and cluster cells into groups that were recognized by different sets of antibodies. And so they were clusters of differentiation. So, this one cluster, CD4, were all recognized by this one cluster of antibodies all recognized the same type of cell. And CD8 recognized a different cell. What we know now, because we have a lot more information, is that CD4 is a specific protein that’s expressed on a subset of T cells. And CD8 is a protein that’s expressed on another subset of T cells. And these are called co-receptors, because the actual T cell receptor is called the T cell receptor. And it recognizes fragments of proteins that are presented in the context of something called major histocompatibility complex, or MHC. So, this gets, this is a little bit confusing and a lot of verbiage here, but what happens is, for example if we’re talking about a tumor: the tumor has antigens in it, it chops them up, it puts them in these little things called MHC and it pops them up onto the surface. And if a T cell receptor can see that fragment in that MHC, it will be directed to do something against that cell. So if we have a CD8 T cell, these CD8 T cells are called cytotoxic, that’s why we want them for this CAR T cell therapy, because they have these basically weapons that they can deploy on the cell to kill the target cell. And so if they see their antigen, in this little MHC, then they’re going to deploy their weapons and kill the tumor cell.
VINCENT: So is it correct to say that all these CD8 T cells that are flowing through us and doing surveillance of peptides in these MHCs, I like to think of hotdogs and hotdog buns sitting on the surface right?
CINDY: Exactly, it’s perfect yep.
VINCENT: If they say oh this is something I recognized from day 1, they leave it alone, right? So if it’s self, nothing happens, but when it’s foreign, that’s the thing that sets them off.
CINDY: That’s right.
VINCENT: And foreign is something they didn’t see when the child was developing and its thymus was developing and all that, right?
CINDY: That’s right.
VINCENT: OK. So we have a lot of different T cell receptors in us. Just like we have lots of different antibodies, right?
CINDY: Yes we do. And that’s, that’s something we can cover another time, but it is spectacular how our immune system develops this repertoire of cells that can recognize millions and millions of different things.
STEPH: Right.
CINDY: And both T cells can do this and B cells can do this.
STEPH: Well I was thinking, you know the steps involved for recognizing self vs. non-self, I mean usually always there’s actually one there’s more than one, more than two steps, because you can’t have your cells recognizing things and having a reaction to yourself. So usually there’s a lot of other co-receptors involved with either a TCR or a T cell receptor complex that has to have this lock and key mechanism so that you don’t attack self. And you’re really sure if you’re gonna employ this inflammatory response- you’re sure it’s something that’s pathogenic or a tumor. So we’ll talk later about that more.
VINCENT: I think we oughta do a self/non-self episode yeah.
STEPH: Yeah, yeah. It would be great title names we could come up with.
CINDY: And the problem is is it’s never black and white, and that is gonna be the hardest thing for the listeners on this podcast and the hardest thing for the immunologists here to try and describe. Because everything has an exception. And what you were saying Vincent is right, where you know, if a cell saw something during development it’s gonna say OK I’m not gonna respond to that. And in fact we have a mechanism to sort of just make sure they never even make it out of the thymus.
VINCENT: They kill them right? Yeah.
CINDY: They kill themselves, yeah. But we know that some of these can get out. We have autoimmune disease, right?
STEPH: Right.
CINDY: It, it happens…
VINCENT: You bet. Yep.
STEPH: Processes fail.
CINDY: Right, it fails. So this is where that regulation comes in really important. So what Stephanie was saying about you know, making sure we have multiple fail safes and multiple signals that need to be engaged for these cells to be deploying their other armament of weapons is important.
VINCENT: So you said what they decided to do was take some antibody, the combining site…
CINDY: Right.
VINCENT: …and combine it with the T cell receptor.
CINDY: Right. Because the problem with this hotdog in a bun and this MHC and this antigen presentation, all this kind of stuff- the problem is is that everybody has different MHCs, and we can talk about that another time too. It is the most polymorphic gene in our genome, so there’s lots of different versions of it and everybody has different ones. And so if you’re trying to think about some sort of therapy that we can use in multiple people, it’s never gonna work.
STEPH: Right.
CINDY: And so everybody’s presenting different peptides in their MHC molecules and so it gets really muddy. And so the idea was well can we take these really potent CD8 T cells that are good at killing things, and use these antibodies that we know we’ve already been able to use to target tumor cells and put them together. So what they wanted to do was take a chunk of the antibody. So B cells make antibodies. And they-the cool thing is is that the antibodies are not restricted to this MHC presentation or anything else or this chopping up of proteins into little peptides and putting in the MHC- none of that is required. Antibodies can recognize things on the surface of cells and and they can just do their thing to what we call native antigens. The other cool thing is that they can also recognize things like nucleic acids, lipids, sugars, and proteins, whereas T cells can only recognize proteins. So if you, if you bring in this B cell part of it, you really widen your field of play of what you can try and target.
VINCENT: So you’re not even using the T cell receptor as anything but a, an anchor, right?
STEPH: Right.
CINDY: You’re using it to drive the signaling part of it.
VINCENT: Okay.
CINDY: So, when we think about a receptor, we think about the part that’s outside the cell binding to something. And that’s a ligand or an antigen, or whatever it may be. And then that protein goes through the membrane, it’s called the transmembrane domain. And then it goes inside of the cell, in what we call the cytosol. And it’s that inside part that’s absolutely critical. Because when the outside part binds to its ligand or antigen, somehow there’s a physical transfer of information to the inside of the cell that then signals that cell. And so in the case of a T cell, when the T cell receptor sees its peptide:MHC, it it transmits a signal through some other proteins that we don’t need to go into the details about, but it transmits signals into the cell, it tells the cell you saw something, you need to activate and kill. And so it mobilizes the little vesicles it has inside of its cytoplasm and discharges them out to where it was contacting the other cell. And so then it kills the other cell.
VINCENT: It seems like a leap of faith to assume that making this chimeric receptor would still work that way, right?
CINDY: Absolutely! And…who knew it could work?! I mean, seriously, you’re taking one part of the B cell, you know, the antibody, the B cell receptor, and just chunking it on to the T cell receptor and saying, pray, let’s see if it works. But it did! So, it’s amazing! It’s absolutely astounding that this works. But so you now have this fusion of this little chunk of an antibody to this transmembrane domain and the signaling part of the T cell receptor. And, and so what happens now is…
VINCENT: And that’s the CAR part of the…
CINDY: This is the chimeric antigen receptor, right. So this is the-this is the sci-fi world where we took part of the B cell receptor and part of the T cell receptor, put them together and made this chimera. Never existed in nature. It still doesn’t except for our synthetic version of it. This is not something a cell would ever make or a human would ever make or any other animal would make for that matter. So this is totally somebody came up with this in their brain and they and they did this. But what it now does is it allows this really high affinity antibody part to target what you want it to target, and then it activates a T cell and the T cell kills the tumor.
STEPH: That’s so cool.
CINDY: So the first way to do this was they said OK, well we know what what works really well? Well if we take this anti-CD19 antibody, monoclonal antibody, we put it into people with B cell tumors, it kills the B cell tumor. So let’s take a chunk of that antibody and let’s fuse it on the T cell and we put, you know, they put they have to harvest a patient’s T cells, and then they take this fusion construct-they take the DNA they made this sci-fi version of this chimeric receptor and they transfect it into the cells. That means they put that DNA into the patient’s T cells so the patient’s T cells now express this new protein this novel protein. Then they have to grow them up in outside of the body so you get lots of them, and then they put them back in the patient and they cross their fingers and they see what happens.
VINCENT: So do they do they purify CD8 or just total T lymphocytes?
CINDY: So that’s a great question. Originally they just said let’s get the effector T cells; that means the CD8 T cells, the mature ones, because they already have all of these weapons that they can deploy. But now people are starting to get much more sophisticated and are looking at more stem-like cells and then differentiating them in vitro or letting them…and differentiate in vivo. And then there is a mess of various different types of T cells. We have memory T cells…
STEPH: Right.
CINDY: …that have already responded to things, we have naive T cells that haven’t yet responded, and then there’s lots of different kinds of memory cells. So different people are taking this and purifying these various different populations of T cells and then putting them back in.
STEPH: I would assume that-so thinking about starting from a T cell that’s naive, it probably has more potential to proliferate than a memory cell or a memory effector cell. Is that what is seen? That they’re looking at is the naive T cells? Have they gotten into that or is that still developing? Finding out which type?
CINDY: So…it’s still developing. Mostly they’re going towards the memory cells, because they can expand them ex vivo.
STEPH: OK.
CINDY: And they do have more effector function. Although, you know, there’re like you said, there are advantages to using these naive T cells. So, for example let’s say if unfortunately you got influenza this year and it was a new version that you hadn’t seen before and there were new T cells that needed to get activated in order to kill the flu- those are those naive T cells, they haven’t seen anything before. And so it takes them a little while to get up and going, and it takes them a little while to synthesize all of these weapons to be able to deploy them on the infected cells, and so it just takes longer for those cells to come up to speed. However, if you got infected with a flu that you had seen before or that you were immunized against if you were smart and got your flu vaccine this year, then those T cells already are primed to go and they have all of their effector molecules and they can deploy them very rapidly. And so it’s a tradeoff between do we wanna go for a naive cell or do we wanna go for a memory cell? Disadvantage of a naive cell is remember we have-we talked about this already- we have these checks, we have these fail safes and these multiple steps that the cells need to receive multiple signals in order to be activated. And so those naive cells still have those requirements, and so now if you put these chimeric receptors into those naive T cells they still need those signals in order to be activated, because if you just get the signal through the T cell receptor, it doesn’t activate the cells enough.
STEPH: And I think I said that the opposite; what I meant to say yes of course an effector memory, a memory T cell’s gonna have a greater capacity to proliferate if it has, if it’s seen the antigen or the pathogen for the second time. But I’m thinking in terms of a naive T cell where what you’re saying is those costimulatory co-receptors and receptors have not been activated so potentially their baseline stimulation levels are lower…
CINDY: Yes.
STEPH: …meaning maybe there’s a higher there’s an increased ability to proliferate in the future-I guess that’s what I was thinking of…
CINDY: Oh…OK. Fair.
STEPH: …maybe I said that backwards but, yeah.
VINCENT: Cindy, something you said earlier, kind of a throwaway comment- you said you know you take out the T cells and you grow them. At one time we didn’t know how to grow T cells right?
CINDY: We did not know how to do that! We do know…and that’s a whole other can of worms we can open but immune cells talk to each other with something called cytokines, and they these are growth factors for immune cells, and they do a lot of other things too. They’re just ways for cells to talk to each other. But one of the ways that T cells make more copies of themselves is they get a signal that says proliferate. And that’s through something called interleukin 2 or IL-2. And so if you feed these T cells IL-2 in culture, you know, they’ll grow and they’ll make more copies of themselves. So that, so you know, each step of this whole amazing process to get these CAR T cells is based on fundamental discoveries in basic immunology.
STEPH: Yes! Basic research.
CINDY: Every single step.
VINCENT: If I’m not mistaken, it was Bob Gallo who figured out you needed IL-2 to grow T cells, and that eventually led to being able to grow HIV in T cells…
STEPH: That’s right.
VINCENT: …as well. You know, so it’s all it’s all, you know…
CINDY: All interconnected.
VINCENT: Interconnected, yeah.
STEPH: So this first CAR T cells-were they successful and did…are newer ones?
CINDY: Right- there was a little oops in the first one. Because they thought well let’s just fuse it to the signaling parts of the T cell receptor. And the problem with that is remember we said there are these fail safe saying you need more than one signal to activate the T cells. Well if you activate just the T cell receptor without these things called co-stimulation, the T cell actually shuts down. And it becomes anergic. And so this is called signal one without signal two. So we need both signals for the T cells to proliferate. So then we got smarter. And what they did was they said OK, that didn’t work, so we’ll just add something else to the cytoplasmic part of this construct. And so what they did was they took the co-stimulatory fragment from the cytosol from the co-stimulatory molecule the part that signals in the cytosol and they just stuck that on and…it worked! So it was able to signal through both the T cell receptor fragment that was on there and the co-stimulatory fragment that was on. They just keep chunking things on and they all work, it’s amazing.
VINCENT: So when you say when you say they work-do they look at this in animals first, or…
CINDY: You know you can do this in cell culture.
VINCENT: OK.
CINDY: And I guess-and I didn’t go back and look at each part of the literature this way of how they came about making these different versions of these things- but my guess is they were able to screen in vitro.
VINCENT: OK.
CINDY: Just add on- do we need a linker do we not need a linker? How much of the cytoplasmic tail do we need? Do we need this whole molecule or part of the molecule? And there was probably thousands of different iterations of these things that various different labs did before they got it right. But for us it seems like oh they just stuck it on it worked, yay. But so, so the second generation of these CAR T cells they got better. They put this, you know, this co-stimulatory fragment on and they had the T cell receptor on and they had the transmembrane domain and they had the single chain antibody fragment from the…that recognizes the CD19, and voila, it works. And so there…it really is amazing. You put them in, they eliminate the B cells completely. Then they ran into another little problem. And so everybody thought that if you put these things in they would do a little bit and then they’d die. But it turns out that one of the very first people who got this infusion- it’s been 10 years.
STEPH: Wow.
CINDY: They still have CAR T cells. And-guess what- not a single B cell in their whole body.
STEPH: Which would cause problems if they get some, you know, infection or something.
CINDY: Right!
VINCENT: So what you’re saying is these original patients still have the infused CAR T cells.
CINDY: They do.
VINCENT: And that’s so weird because you didn’t put in any stem cells, which are supposed to give rise to these right?
CINDY: So these are memory cells.
STEPH: Yeah long-lived memory cells-is that essentially what they concluded?
CINDY: That’s what I understand. They are long-lived memory cells. And so, so obviously it’s not a good thing that you don’t- it’s a good thing this person no longer has B cell cancer. It’s a bad thing because you don’t have any B cells.
VINCENT: So do they get lots of infections?
CINDY: So what they do is they have to get infusions of…
VINCENT: Antibodies. Yeah.
CINDY: Antibodies.
STEPH: Antibodies.
CINDY: Every couple of weeks, yeah.
STEPH: And that’s a lot of going to the hospital every two weeks to make sure you have antibodies to fight off infections.
CINDY: Yeah.
VINCENT: I remember I remember a story we did on TWiV with…had a patient who had been immunosuppressed and had to get antibodies regularly and they ended up getting polio because the polio antibodies they were getting weren’t good enough- there was some problem with their titer.
CINDY: Oh, god.
VINCENT: You know, so lots of issues right? You have to know what’s gonna be assaulting people and make sure…
CINDY: Yeah.
VINCENT: …they’re right and what is right? You know, you never know.
CINDY: Right.
STEPH: Right, yeah. And with that patient, he didn’t seem to have any complications in terms of his body overreacting to the CAR T cells, his body seemed to accept them and use them? I mean ten years is a long time.
CINDY: So, so I don’t, I’m not gonna claim that there were no side effects at the beginning.
STEPH: Gotcha.
CINDY: Because we’ll get to we’ll get to these things. They’re pretty dangerous actually.
STEPH: Yeah.
CINDY: You unleash these T cells into the body doing this business that they’re doing. But yeah so each iteration of this we get a little smarter, right? And so somebody said well you know maybe we don’t wanna just leave them in there. And the other thing is is if these CAR T cells go in and they start attacking things that we didn’t expect them to attack…because remember, we don’t have normally antigens that are specific to a tumor and nothing else. So you put in these T cells and they could start going causing trouble where you don’t want them to be. So people got smart and they said well let’s put a kill switch in. And so what they do is they put in a like a toxic gene or a gene that will kill a cell if you give a drug that won’t harm a normal cell. And so they’ve used things like the herpes simplex virus thymidine kinase, which will go into cells and it doesn’t cause a problem but if you give the drug ganciclovir, now it’ll kill those cells. So, so they engineer now- so now they’ve got the single chain antibody fragment, the transmembrane domain, the T cell receptor, the co-receptor, and now if you put in this cytotoxic gene that’s also expressed, now if these T cells start causing a problem you can give the drug and bam the T cells are gone. So that’s great, right?
VINCENT: Very smart, yeah, love it.
STEPH: Yeah!
CINDY: So it’s amazing, you know, you start digging into what’s going on here and things just get cooler and cooler and more sophisticated.
STEPH: And like you said it came from basic immunological research, you know, in academic centers. I think there was a senator, some senator that said you know, the biggest breakthroughs in biomedical research come from companies. And of course not to say that they don’t have breakthroughs as well but I think it’s basic research and understanding mechanisms that gets us to this very cool point.
CINDY: Right!
VINCENT: For sure.
CINDY: And the thing is you don’t know where two fields are gonna collide and have something amazing happen, right?
VINCENT: Yeah.
STEPH: Right.
CINDY: And so, so keeping your eyes broad and reading broadly is so critically important.
STEPH: I like what Vincent says, he says find good people just give them money and let them do the science. And see what they come up with.
CINDY: Yeah.
VINCENT: Hey make me head of NIH, that’s what I’ll do.
STEPH: Maybe that’s your future after podcasting.
VINCENT: I don’t think so. But you know, and plus herpes simplex TK you know.
STEPH: Yeah.
CINDY: Yes!
VINCENT: People worked on that for years!
CINDY: Right!
VINCENT: And you could say why are you doing this? You know, we know what it does for the virus, but it turns out to be really useful in many more ways than just this too, I mean…
CINDY: Absolutely.
VINCENT: It’s just it’s incredible. Really you have to let people just be curious.
CINDY: And you have to you have to have different types of people. Like you need people who are, their whole life goal is to work on this HSV thymidine kinase, right?
STEPH: Right.
CINDY: They need to understand it inside and out. And then you need people who can step back and say, hey that’s a cool paper-wait can I use that and put it on this over here?
VINCENT: Yeah.
CINDY: From what somebody else is doing and then combine all those things together and make these crazy crazy new ideas and and new therapies and completely different from what anybody was thinking about.
VINCENT: Yeah. Which is basically it’s hard to predict, as you said.
CINDY: Right.
VINCENT: You know, where things converge. The idea that you can predict- and often we’re asked to in our grant applications…
CINDY: We are.
VINCENT: …predict you know, where this is going. Who knows? Just do good science, it’ll work. We’ve known that, it always turns out to be the case.
CINDY: Right. So I just…yeah go ahead.
STEPH: One of the things I listen to, this sports radio station and they have the James Cancer Center out of Ohio State- I have been hearing a lot more about immunotherapy and the blessings of it and how it’s gonna work for everybody and I understand that’s a good marketing tool. But what are some of the drawbacks? Because it can’t work for everyone.
CINDY: Right. So, one of the big problems is that everything I’ve talked about so far and the first gen, second gen, this that and the other. All targeting these liquid tumors. So when we talk about a liquid tumor we’re talking about a leukemia or lymphoma. So it’s an immune cell, not a solid tumor. And so you infuse something in the blood and those T cells are going to easily reach those leukemia cells and they’re you know they’re floating around the body or they’re in a lymph node, or they’re doing their thing. And the original problem we were talking about at the beginning is that it’s hard to get the immune cells into the tumor, and once they get in the tumor, they get shut down. So this has not really panned out that well for solid tumors. So the antigen is more challenging. So if you’ve got a bunch of B cells and you can kill off anybody who’s expressing CD19 and obviously this patient can survive 10 years without any B cells just giving antibody infusions, you’re OK. But if you’re now gonna target an antigen that’s on a solid tumor that’s also expressed elsewhere in the body, you’re gonna get what’s called on-target off-tumor toxicity. And this is something that is unique to therapies like immunotherapies where antibodies or CAR T cells are targeting an antigen that is supposed to be preferentially quote unquote, expressed on a tumor.
STEPH: Right.
CINDY: And so they’re doing what they’re supposed to do, it’s just not where you wanted it to be. And so there are examples where they’ve infused these CAR T cells that have different targeting components so they’re not necessarily targeting CD19 they’re targeting different antigens. And all of a sudden they find out oh oops-that was expressed on the lung…
STEPH: Lung yeah.
CINDY: …when you thought it was only in the prostate.
STEPH: Right.
CINDY: Or that was expressed in the brain when I only thought it was expressed in the lung. Or I thought it was in breast tissue and now what’s happening to their liver? So we get these surprises, and so these T cells are really potent and that’s one of the reasons why they have these kill switches. And the other problem that you have is that- Vincent was talking about escape. And the tumors escape and they can escape these CAR T cells too.
STEPH: Guess they’re tricky.
CINDY: And so if you’re targeting CD19 and they downregulate CD19, they become resistant. So it’s…you’re back to the beginning and so something that I found that I thought was really cool- that newer things are trying to put two together. And they’re requiring an ‘and’ signal. So this is this idea of Boolean logic, where you have to have something that’s on a tumor and something else that’s on a tumor. And A might also be on one tissue and B might be on another tissue but you need A and B together in order to signal and kill.
STEPH: Ok.
CINDY: And so they’ve done this- or they have a ‘not’ signal. Something that’s normally expressed on a healthy cell and not expressed on a tumor cell. So if you have the plus signal and you get a minus signal, that means it’s a healthy tissue. But a plus signal without the minus signal-that’s an unhealthy tissue and you kill that. So they’re using this, you know, this Boolean logic that they use in like programming or whatever to turn on or turn off or tweak or you know, really more finely target a tumor specifically.
VINCENT: And how would you make two specificities? Just two different receptors on the T cell?
CINDY: Yeah. So so you can make two different CARs.
VINCENT: Yeah.
CINDY: And so one is gonna target CD19 and one will target something else. And basically what they do is they put half of the signaling part on one and half the signaling part on the other and you need to…you need to trigger both in order to activate the T cell.
STEPH: Right.
VINCENT: Remind me, why doesn’t when you do this CAR T cell therapy why doesn’t why don’t the cells get exhaustion from PD…
CINDY: I think they can. I think they can and so people are trying to, for example, combine checkpoint inhibitors with CAR T cells.
VINCENT: I see.
CINDY: To keep the CARs running.
VINCENT: Very good.
STEPH: Oh that’s a good title. So this’d be similar to this new approach would be similar to the bi-specific antibodies in the last podcast?
CINDY: Right. So you want two things to be recognized in order for the effector function to happen.
VINCENT: And then if you want the other situation, something that’s not gonna work, something that is on a normal cell but not on a tumor, how would you do that?
CINDY: Right. So they take advantage of these checkpoints and they they fuse that targeting molecule to the checkpoint signaling part.
VINCENT: I see.
CINDY: That shuts a T cell off.
VINCENT: Got it. Nice! Very cool.
CINDY: Yeah.
VINCENT: Very cool.
CINDY: Yeah! So so so they’re great, and they can also be used for other things, and I don’t wanna go in great detail on this and maybe we need to do a second episode on this, but but people are starting to think outside of cancer. So autoimmune diseases can be malfunctioning T cells or B cells and if we could target them and eliminate them, that’s another way that CAR T cells could be used.
VINCENT: Neat, yeah.
CINDY: Yeah, cause for example in multiple sclerosis it’s T cells that are recognizing part of the myelin sheath that’s wrapping around neurons and attacking them. If we could attack the T cells that are attacking the neurons then we could kill those and eliminate them and alleviate the disease.
VINCENT: So you could do that with a CAR T cell?
CINDY: You could do that with a CAR T cell. So you could actually make an antibody that recognizes specifically the T cell receptor that’s causing of the T cells that are causing the problem and target them specifically.
STEPH: Yeah, right.
CINDY: So there’s really no limit to what you can target.
VINCENT: You mention here in the notes about a fungal infection-
CINDY: That’s right!
VINCENT: You can even do infectious diseases right?
CINDY: So I thought this was cool because what they did was they fused what’s called a part of a pattern recognition receptor and we’ll get into that when we talk about Immune 101, but basically it’s a receptor that’s designed to recognize something foreign. And so in this case it’s a receptor that’s designed to recognize a fungus, it’s called Dectin-1. And so they took this idea of the CAR T cell instead of fusing to a single chain antibody that recognizes CD19 they just took the binding domain of this pattern recognition receptor that recognizes fungi and put that on there. And so, fungi are large, and if the T cell comes in and recognizes the sugar through this pattern recognition receptor then they discharge their killing mechanisms on the fungus.
VINCENT: That’s very cool.
STEPH: That’s great, that’s very cool.
CINDY: And they also have done this with HIV. So HIV infects CD4 T cells, so if you could target CD4 T cells and eliminate them, you eliminate the cells that are infected and harboring the virus. And so they’ve made CAR T cells that are targeting CD4 and so you can target any CD4 T cell and eliminate it and preferentially eliminate HIV. Now, we all know that that’s not the only reservoir, they sit in macrophages and other things…
STEPH: Right.
CINDY: So it’s not perfect, but it could dramatically reduce viral load.
VINCENT: Yeah problem is that in many of the long-lived T cell reservoirs, there’s no viral protein on the cell surface, right? They’re silent.
CINDY: Right!
VINCENT: And so, so these CAR T cells wouldn’t ever see them.
STEPH: See them, yeah.
CINDY: They wouldn’t they wouldn’t see the virus, but they see CD4, because CD4 is always expressed on the T cell.
VINCENT: So you’re just gonna get rid of all CD4 T cells?
CINDY: Yes.
STEPH: OK- you’d have the same issue of AIDS then, right?
CINDY: You would, you would deplete, yes.
STEPH: Right, right.
CINDY: But presumably you would recover.
STEPH: Well and I think it’s kind of where we’re looking into very personalized medicine.
CINDY: We are.
STEPH: I think Vincent had brought-he really wants to see where you would look at a mirror, it would scan your body…
VINCENT: That’s right.
STEPH: It would tell you what type of cancer or what your malignancies are and designate what your treatments would be. I think this, cancer immunotherapy is probably the closest right now we are to personalized medicine, which of course comes with a lot of cost, in terms of money.
CINDY: Yes…
STEPH: That’s involved with it. But it’s very neat to see how far we’ve come and of course I think the next step is finding out why some people don’t respond and why tumors you know, hide their CD19 and why some of these people actually don’t go into remission based on some of the mechanisms that we learn.
CINDY: Yeah.
VINCENT: The other thing we should point out is that these more recent CAR T cell therapies don’t use transfection anymore but they use actually HIV-derived viral vectors to deliver genes right?
CINDY: They do.
VINCENT: Isn’t that cool?!
CINDY: They do. They make virus and then they infect with the virus. And I think the advantage there is anybody who’s done these wet bench experiments, transfection isn’t usually very efficient and actually it’s pretty horrible when you talk about primary cells…
VINCENT: Oh yeah. For sure.
STEPH: Yeah.
CINDY: …taken out of a patient. But, unfortunately or fortunately HIV and other lentiviruses and retroviruses are really good at infecting even primary cells. And so, yeah they make these virus and then they infect in the culture and you get almost 100% of the cells expressing these.
VINCENT: And that’s what I…I love to point out- you have this scourge of humanity, HIV, right? Which we have modified to use for gene delivery.
CINDY: Right.
STEPH: Right.
VINCENT: How cool is that. How cool is that.
CINDY: It’s amazing.
STEPH: Awesome.
CINDY: It’s amazing.
VINCENT: I love it. So what do we have approved right now, Cindy?
CINDY: So there are two CAR therapies that have been approved. One was Kymriah by Novartis, and that was in August of 2017, so these are very very very new. And the other one is called Yescarta by Kite Pharmaceuticals, which I believe was just bought by Gilead for 12 billion dollars. And that was in October of 2017. And so, so there are two of these therapies out there. They’re both for B cell lymphomas, and they’re both targeting CD19.
VINCENT: And that…they must be slightly different so that each company can do their own, right?
CINDY: I think they’re they are they are slightly different but they both use the same basic idea. I think if it has a slightly different sequence, it’s it’s gonna be a different drug, right?
VINCENT: Mmhmm.
STEPH: It’s interesting that it’s approved for children and young adults, I mean what is it about…I mean does that mean they couldn’t use it in adults? I mean I see that the Yescarta can be…
CINDY: Right.
STEPH: …for adults, but it’s interesting, it must be, you know, how naive their B cells are.
CINDY: I think…I don’t know…
STEPH: Immunological age maybe?
CINDY: So, I think the reason why they did this was a couple of things. And maybe maybe listeners can clarify this is they have more information.
STEPH: Yes! If there’s any clinicians out there.
CINDY: But I think one is that this is such a horrible disease for these young children.
STEPH: Right.
CINDY: That they get this lymphoma and it it’s it’s one of the easiest ones to cure, which seems, why would that be a target, right? Cause’ I think you can cure about 80% of these children with traditional chemotherapy.
STEPH: Okay.
CINDY: The problem is, is those 20% that don’t- relapse and they’ll die.
STEPH: Right.
CINDY: And it is, it is horrible for these little kids. And so this is designed for those refractory acute lymphoblastic leukemia in these little kids. Because it’s just a desperate attempt to try and save them.
STEPH: Right.
CINDY: And they have these B cells, and the B cells express CD19, so that’s who they targeted with that original therapy.
VINCENT: So do you know what’s in the pipeline?
CINDY: I don’t, but as far as I understand, there’s like 20 or 30 different clinical trials going on right now with various different versions of CAR Ts for for different types of both lymphoma and leukemia as well as now solid tumors. So they’re trying to target the solid tumors. And they did-so one of these ways to target the solid tumors is try to overcome these immunosuppressive environments. So one way to do that is to combine it with the monoclonal antibodies targeting checkpoint inhibitors. Another way to do it is they’ve made something called an armored CAR, it’s like an armored tank, where they’re going to express a molecule or an enzyme that’s gonna shut down the suppressive environment of the tumor. So it inactivates one of the molecules that the tumor secretes that shuts down a T cell response. Or, the T cell now expresses an enzyme that allows it to degrade the tissue and get into the tumor better. And so these are ways that they’re sort of armoring up the T cell to keep it intact and get into that tumor microenvironment so it can actually do its job.
VINCENT: Neat.
CINDY: Yeah.
STEPH: Very neat.
VINCENT: You could also I guess use this for transplantation purposes, right? If you wanna target the cells that are rejecting the organ?
CINDY: I guess, I hadn’t thought about that it’s interesting. Yeah, I guess you could if if you knew the targets. I’m not sure in the case of graft-versus-host disease whether you’d be able to distinguish between the host T cells and the graft T cells to target…
STEPH: Right.
CINDY: …the graft T cells specifically. I can’t right off the top of my head think of how you would do that, but I’m sure somebody’s clever…
STEPH: Yeah.
CINDY: …enough to figure it out.
STEPH: It’s probably like what you said before that you would just get rid of all CD19 cells and you know, cells…
CINDY: Hope for the best.
STEPH: Hope for the best- you solve that problem and then okay maybe they have to get antibody passive transfer but at least, maybe that’s the strategy.
CINDY: Yeah. And I guess you usually ablate the patient first before you give them the graft so in the case of bone marrow transplant for sure you do that. So most of the cells that are gonna be there are gonna be of the graft origin, so. I guess that’s how you could target it.
VINCENT: So Cindy, the last thing- how much does this cost?
CINDY: So unfortunately…
STEPH: Dun dun dun.
CINDY: …and we’ve mentioned this before and you’ve mentioned it on your other podcasts as well. Right now, it’s between 300 and 500 thousand dollars per person. It’s a one-time thing, so you could argue well you only have to do it once if it works it’s great.
STEPH: If it works…
CINDY: And you’re saved.
VINCENT: That’s just the therapy, that’s not the hospital stuff and everything, right?
CINDY: This, this is the big thing. Because it’s not just the treatment. These these are incredibly powerful and incredibly dangerous. And the types of side effects that come with this are entirely new territory. So it’s not at all like what we see with chemotherapy. You’re not losing your hair and having some intestinal issues and your skin is getting dry and sloughing…these are, you are powerfully activating the immune system to go and kill lots of cells quickly. And so there’s two things. One you can have this on-target off-tumor attacking organs that it’s not supposed to be attacking, but the other thing you have is that the T cells, when they’re doing the right thing in the right place at the right time they’re killing a lot of cells fast.
STEPH: Right.
CINDY: And when you do that you release things that alert the immune system to the fact that there’s damage and there’s tissue repair that needs to happen. And this induces a massive inflammatory response, and we get something called a cytokine storm response. And so, there’s this massive production of all these inflammatory cytokines that trigger a whole bunch of different sequelae: blood pressure drops, temperature drops, you get edema, and all of these other systemic effects that are really hard to control. And so it it requires a lot of physician time to treat these patients as well and manage their, the tumor response that they’re supposed to have comes at this cost that they have to manage.
VINCENT: Mmm, yeah. So right now, I assume since it’s licensed people are being treated using these, right?
CINDY: As far as I know, yes they are. Yep.
VINCENT: So who’s paying for this?
CINDY: I don’t know!
VINCENT: You either have really wealthy people only, which is not right, or the insurance companies have to make a decision whether they’re gonna pay for this, right?
CINDY: That’s right.
STEPH: Right.
VINCENT: So that, you know, with technology comes this issue that it costs a lot of money.
CINDY: That it does. And our healthcare system has got a few problems.
STEPH: Yeah it’s not really in a place where it’s gonna support people who come out of poverty having cancer being able to treat themselves with this.
VINCENT: No.
STEPH: So we could only hope that with more research and development dollars going into clinical trials that we’ll know more, the production will be less, and eventually that will trickle down but unfortunately what that means is today the people who are suffering, there’s a cost to that.
VINCENT: It’s so unfortunate because I think anything developed by humanity should be available to everyone, right?
CINDY: Yeah.
VINCENT: In theory. But it’s not. And it’s really unfortunate. Because…
STEPH: Right. Because really in this county you know, to stand on the morals of the equal access or equal happiness for all people it would just be equal access to healthcare that is equivalent to that.
VINCENT: Unfortunately, it’s a political issue, right?
STEPH: Right.
CINDY: It is.
VINCENT: And some people some people believe that and others do not, you know.
STEPH: Right.
VINCENT: It’s really amazing that a number of people feel that everyone should not be entitled to…
STEPH: Right.
VINCENT: …government subsidized healthcare. The other issue is that when one of these companies when it was licensed one of the one of the officials of a company went online saying well it’s expensive but it’s gonna save your life. Which I thought was really not…
CINDY: Irresponsible.
VINCENT: Because…
STEPH: Who’s this PR person? He’s gotta get…
VINCENT: It was a CEO of one of these companies!
STEPH: He’s gotta go to some seminar.
VINCENT: And the thing is, what you should say is well we spent 3 billion dollars on this and we have to recover it and then once we do maybe we could lower the price that would be the reasonable thing to say but, you know. And there are gonna be more of these, so it’s gonna be an issue going forward, right?
STEPH: Right.
CINDY: Yeah.
STEPH: Well Cindy I think you did a great job…
VINCENT: That’s great.
STEPH: …explaining it. I really, you know, I’ve done, I’ve known about this I’ve done a lot of reading but I think you really succinctly brought it together in a package that made sense for people and of course they can let us know, but it it went a little deep but then we came back up for air, we described things, and I think you did a great job.
CINDY: Thank-you.
VINCENT: Yeah, it was lovely.
CINDY: I loved researching it. It was really fun. Like you, Steph, I had known about this and I sort of knew generally what it was and the chimeric receptor.
STEPH: Sure.
CINDY: But digging deeper and seeing all these incredibly creative ways that people have tweaked this system and the amazing way that all of these basic biomedical findings are just have come together in this package that now offers hope.
STEPH: Right.
CINDY: To people who didn’t have hope.
STEPH: Right!
CINDY: And I think it’s fantastic.
VINCENT: So I have, I’m teaching now my Virology course. The last lecture of the course, it’s not till May, is on gene therapy.
CINDY: Yeah.
VINCENT: And this is gonna go in it because…
CINDY: Great!
VINCENT: It’s brand new and it’s a great- you know there aren’t many approved gene therapy examples.
CINDY: No.
VINCENT: A handful of em. And this is a great one to- and you know the science behind it is just cool, right?
CINDY: It is.
VINCENT: You just can’t deny it, it’s just great.
STEPH: Right.
CINDY: You can’t.
STEPH: And one thing before we move on I did just wanna touch on one of the interesting things that they’re looking into is the effect of the microbiome on immunotherapy. And in our lab we do work with the microbiome and its effects during a viral infection in neonates or in young animals and so, I posted a paper and maybe we could share it but what they saw was in melanoma patients receiving the checkpoint inhibitor, pretty sure it was PD-L1 or PD-1, PD-L1? And they showed that people who had a higher diversity of bacteria, and that included having species from the genus Rumococcus, I’m sorry, Ruminococcus, which is in the class of Clostridia, and I tell ya, Clostridium, people who study that, that is a fascinating bacteria. It seems to be very much in good situations it behaves and in bad situations it can really cause problems. So, you know, how the microbiome effects how we treat cancer patients I think is another new frontier in personalized medicine. So, I posted that in there. I just thought it was really fascinating.
VINCENT: That’s neat! Very cool.
STEPH: Yeah, yeah.
CINDY: Kinda makes your head explode…
STEPH: Yeah.
CINDY: …when you think about all these things that can connect together and it’s impossible to keep all those moving pieces up in the air and trying to figure out how these patients we basically just look at one thing at a time then try and connect it back.
STEPH: Right.
CINDY: But the bigger systems biology approach to understanding how all this works is just mind boggling.
STEPH: For people in training, for young people looking to be scientists, there’s a lot out there to be excited about. I think what is gonna be the limiting step is is there space for everyone to do that cool science and is there money for that?
CINDY: Yeah.
VINCENT: Should we do a few e-mails?
STEPH: Yeah.
CINDY: Yeah sure. Let’s do a few.
VINCENT: Alright. Cindy, maybe you could take that first one from Matt.
CINDY: Ok. So Matt writes:Dear Immu…Immu…Immu…
STEPH: Knowledge-ists.
CINDY: Knowledge-ists.
STEPH: It’s cute.
CINDY: Knowledge…yeah! That’s cute. I have listened to TWIV for about two years, and nearly wrote in last year after my virology final exam, but never got around to sending it. That’s a shame- you should do that! In that draft I had written how I wished that there was an immunology podcast I could listen to, because immunology is just about the coolest subject out there. Woohoo! I think we agree with that. In fact, I would specifically keep an eye out for any TWIV episodes that were related to immunology. I’m so excited for this podcast, and am eagerly awaiting episode 3. I am in my last semester as an undergrad at the University of Wisconsin and actually just submitted my applications for pursuing my PhD in immunology! Congratulations!
STEPH: Yay.
CINDY: Thus, I look forward to hearing from Steph’s grad student perspective. I had a few thoughts in response to the first two episodes. Firstly, I was glad that the proposed tax plan was a point of discussion. It’s my understanding that the Senate tax bill does not tax tuition wavers, while the House bill does (feel free to correct me, I’m not sure if that is accurate.) Regardless, I thought it was a rather dark coincidence that grad school deadlines were 1-2 days before the bill was passed. I’m sure that like me, many other prospective grad students had the tax bill weighing heavily in their minds. I am also curious if there were prospective applicants that decided not to pursue grad school in light of this bill. Either way, I appreciate you all voicing your concerns for the future generations of scientists, and all those whose lives will be affected by this bill.
So let’s take a second out about this. Because one- I think it’s tragic if anybody didn’t put in their applications because of this.
STEPH: Right.
CINDY: Things change over time, graduate school takes a long time, and the light at the end of the tunnel there- it might look like a very different landscape in research. So please don’t…if it’s something you have a passion for don’t give it up. But the other things we can talk about is now these bills have been modified, is that correct?
STEPH: Yes. They took out that tax/tuition waiver for students. So if you know, it’s hard to say of course what the defining factor was and removing it, but I believe that people calling really does matter. So we can, I guess at this point for this little part of the tax bill maybe pat ourselves on the back for getting our voices heard and staying up to date with it. It’s not included in the…
CINDY: Yeah, I don’t know if it was just in my echo chamber, but boy did I see a lot of it. People complaining…
STEPH: Yeah.
CINDY: …about this. All over Twitter and Facebook and online and in the news and everywhere. I mean they, it really made national news talking about this and how ridiculous it was. And so, yeah I agree with you I’d like to think we made a difference. So you know, it’ll energize people to speak up in the future.
VINCENT: I’m hoping that in a few years we’ll repeal the bill. Because…
STEPH: Right.
VINCENT: …it’s a lousy bill, even without this. And we’re gonna change Congress in two years, and this is gonna go.
STEPH: By the way, is the government back up and running?
VINCENT: It is.
STEPH: OK. Cause I saw on PubMed that big red “This isn’t up to date because of lack of funding.” was gone so.
VINCENT: Yeah so…
CINDY: Right!
VINCENT: It’s back until February 8th is their next…
CINDY: Yeah.
STEPH: Right.
VINCENT: And they have to take their…
STEPH: Which by the way yeah when the government shut down, government scientists have to stop doing their work and that is a big problem in the progress of science.
VINCENT: I follow NASA on Instagram, and they put up a post saying sorry we can’t post until the government is back online. Isn’t that sad?
CINDY: Yeah.
VINCENT: Just, you know.
CINDY: I know the last time this happened I think I was supposed to go for a grant review and I didn’t even, I didn’t know if it was happening or not and the person that was in charge of it wasn’t allowed to e-mail…
STEPH: Oh my gosh.
CINDY: They just, when they shut it, you know, they sent us an e-mail saying if you don’t hear from us it’s probably because we’re not gonna be able to have the review if we’re shut down.
STEPH: Wow.
CINDY: But yeah so it affects review of grants, it affects distribution of funds for researchers who’ve been awarded grants.
VINCENT: However, it does not affect the salaries of Congress.
CINDY: That is correct.
STEPH: No. Or the health insurance. Right.
CINDY: That is correct. But all the other workers…
VINCENT: Which seems…like they should, they should change that I think. Because then maybe there’d be more of a pressure then to get it done.
STEPH: Right.
CINDY: Yeah but all of the other government workers get furloughed and so they don’t get paid. Yeah. So. Alright so continuing…On a lighter note, I was thrilled to hear Cindy bring up CAR T cells during the first episode. Immunotherapy is new and exciting field, and is actually what I hope to specialize in during graduate school.
STEPH: Oh! Perfect.
CINDY: Yeah. The first time I heard about CAR T cells I was blown away [So were we.], which is the natural response to learning what we…that we can engineer a T cell response-how cool is that?! I hope future episodes can discuss multiple types of immunotherapy, like adoptive cell transfer, costimulatory blockades and cancer vaccines. I think discussing PD-1/PD-L1 would be very beneficial even for non-scientists in the audience. Just for those of you keeping track- that’s one of those checkpoint inhibitors. I have been seeing more and more commercials for anti-PD1 drugs, and think that it is important the general public has an understanding of how these therapies work. Thank you all in advance, and I look forward to a great podcast!-Matt Well Matt, you just heard it. We talked about some of this. Thanks for the additional ideas there; cancer vaccines I think are fascinating, and we could talk a lot more about checkpoint blockade if we got into a lot more detail. But I think we covered quite a bit of it earlier in this podcast so.
STEPH: Right. So this podcast is dedicated to you Matt.
CINDY: There you go.
VINCENT: Steph, take the next one?
STEPH: Yeah sure. Courtney writes: Greetings from Omaha, Nebraska I don’t know if ya’ll are doing the weather, but it is a chilly 22 degrees Fahrenheit here. I’ll admit I’m a warm weather gal, nearly 60 in December makes me feel uneasy. I am enjoying your latest episode in Immune. I haven’t completed it, but I do have a question. Do you think seasonality has a large impact upon lymphocyte rhythms? I did post an article that suggests that they could impact immunity. They specifically look at C reactive protein, which is a type of serum protein in the acute immune response and also soluble IL-6. Cindy did note though that of course in Western countries we spend most of our time in ambient temperature between 65 and 75, so likely we might not see these responses. But if you think about people I mean even in this country there’s millions of people who work outside all day long and this…
CINDY: Right.
STEPH: …their, you know I mean depending on the weather this could definitely I believe have an effect on their health and how their lymphocytes circulate throughout their body. So yes, I do think they have an impact but depending on where you live is how large it is. I also put in there depending on the type of mammal you’re looking at- mammals that hibernate, there’s a paper demonstrating that you have a change in the lymphocytes circulating in small mammals that hibernate and that’s also driven by body temperature. And she says, Stay Excellent.
VINCENT: Next one’s from Justin. Waited until episode 2 to say this but please keep up the great podcast. If you find the time, as an analytical chemist I’d love to hear more about analytical techniques you use, thanks. Well…
CINDY: Sure…
VINCENT: We could do that. What would be an analytical technique that we use?
STEPH: Flow cytometry.
CINDY: Flow cytometry.
VINCENT: Ok. Yeah I suppose. That’s the big one for immunology I guess, right?
STEPH: It’s the big one. I mean there’s a lot more things, you know, and looking…mass spec, there’s you know looking at sequencing, but that’s kind of not specific to immunology. But we could we could talk about different techniques.
VINCENT: I guess ELISA also would be…
CINDY: Yeah.
VINCENT: …an immunological technique but used for many fields, right?
CINDY: Yes.
STEPH: Right.
VINCENT: I mean even flow is not just for immunologists, right?
STEPH: Right.
CINDY: So really, yeah it’s not just for immunologists. And all of those things that we mentioned rely on antibodies and being able to use antibodies for different things. So maybe talking about how antibodies are made and what the different things we can use them for would be a useful podcast.
VINCENT: What I think you should do Cindy is explain the ouchterlony test.
CINDY: That precedes my time.
VINCENT: It does?! It’s so funny. When I was in graduate school that’s what we learned in immunology. You know, I and I never got it. I never understood what was going on but it was this agar diffusion assay…
CINDY: Yeah.
VINCENT: …which nobody uses anymore I guess.
CINDY: They don’t. But the principle of antigen and antibody concentrations…
VINCENT: It’s very cool.
CINDY: …and precipitation is is interesting and we could cover that for sure.
VINCENT: So yeah we have a bunch here and we’ll see for next time. But don’t stop sending them in! We love getting your e-mails.
STEPH: Yeah we love it.
VINCENT: Immune@microbe.tv. Let’s do some picks!
STEPH: Great.
CINDY: Alright!
VINCENT: Steph, what’dya got?
STEPH: Well yeah I’ll go first. When you know, really getting into learning more about cancer immunotherapy and some of the things that are on the forefront of the field as somebody who’s not really in that research myself, I was listening to a podcast called Novel Targets. It’s really well done. They are funded through Genentech, which is a company that also produces drugs, immunotherapy drugs, but they say throughout the podcast of course that any editorial decisions are not influenced by Genentech. But it seems like a well-funded and well done podcast that talks about what’s up and coming in the drug development field. So, if you want any follow up for what we’re talking about today, I would recommend that podcast.
VINCENT: Good for them to have sponsorships.
STEPH: I know, I was thinking about that.
VINCENT: And you know Sally Church who’s the executive producer- I’ve known Sally for years through social media. Sally- why don’t you fund us?
STEPH: Yes! We’re…I mean, we could…
VINCENT: On Twitter I always see Sally saying oh I love these these microbe TV podcasts, blah blah blah, and you put your money somewhere else. How sad. That’s interesting. So they’re supported by Genentech.
STEPH: Yup.
VINCENT: And the Loncar Cancer Immunotherapy Index.
STEPH: And the…there’s one person it’s not a panel who does interviews and it’s, I think it’s his main job to run this podcast and he does a really excellent job so I recommend it.
VINCENT: Yeah. Well we, this is, it’s hard because this is not my main job. At least now. None of us, but…
CINDY: Oh, right.
VINCENT: …we do put a lot of time into it.
STEPH: Yes! No ours is excellently done and I think what we give is you know, differing opinions and a back and forth that maybe other podcasts don’t do, so. Of course, you know…
VINCENT: The problem is, I have to say, I’m hesitant to take money from Pharma…
STEPH: I know.
VINCENT: Because then…
STEPH: You’re not gonna hear the end of it probably.
VINCENT: People will criticize you for not being partial, right?
STEPH: Yup.
CINDY: Yup.
VINCENT: So Genentech. But for example on TWiV I can’t take money from any vaccine manufacturer because we completely endorse vaccines and I don’t want people to say that’s because you’re getting money from.
STEPH: Right.
VINCENT: So, I would like to get money from other places, but good for you for doing that. You know the thing is someone can attack you for taking that money.
STEPH: Right.
CINDY: Right.
VINCENT: So you think the podcast is well done, Steph, right?
STEPH: Yeah yeah. I mean I think our…I was gonna say I think ours is better, no I’m just kidding, but…
VINCENT: Of course! Because of the two of you!
STEPH: Of course ours is the best. But then if you’re gonna listen to another one if you have time, listen to all of them on Microbe.tv and then go to Novel Targets.
VINCENT: Alright I’ll check it out. On your recommendation. Cindy, what do you have?
CINDY: So when I was reading all of this literature and things on these CAR T cells and I started reading these names of all of these immunotherapies my head almost exploded and I said I don’t understand what chechenzangusel-something liculala was and so I, my pick of the week is something on immunotherapy nomenclature and this is from the cancer research institute website and they explain all these crazy names of the various different immunotherapies and break down what it actually is is each name is made up of individual components that if you know and can decode the nomenclature, you can figure out what it was. And so an easy one for example is any of the immunotherapies that end in “mab” like Rituximab, that just means it’s a monoclonal antibody. And so the “tu” is for targeting a tumor so Rituximab. So it’s targeting a tumor and the xi in Rituximab actually means a chimeric monoclonal antibody. And so if you have these individual fragments you can understand when you see the commercial for Yervoy and it’s Ipilimumab, you can figure out what that actually means. And you may not know what it targets but you might know oh that’s a monoclonal antibody or…all of the ones that are cell based therapies end in leucel or lecleucel. And so you can figure out what the therapy actually is and what it’s targeting from the name. So all these crazy names with all the Xs and the Ys and crazy little fragments actually makes sense when you have this cheat sheet to understand what the nomenclature is and decode it. So I highly recommend if you wanna try and figure out what all of these crazy immunotherapies are and what these crazy words mean, check out this website because I think you’ll be surprised at how much you can actually understand what those names those crazy names are.
VINCENT: It’s really good, I like it.
STEPH: Yeah.
CINDY: Yeah!
VINCENT: It really breaks them down too. I think it’s very cool.
CINDY: Yup.
VINCENT: Alright my pick is a little fun video, which I discovered on TWiM, which is dropping this week. We did a paper on this really amazing story of in Antarctica there are parts of Antarctica that are actual soil. It’s not all ice. And many people go down there and study these soils and this one paper they showed that there are bacteria, there’s a microbiome in this soil. And it lives off of trace gases in the atmosphere, cause there’s nothing else for it to grow on.
CINDY: Seriously, wow.
STEPH: Wow. That’s crazy.
VINCENT: Anyway I wanted to see the area they were working on so I was looking for photos and videos and I came across this video on Facebook that has nothing to do with the original paper, but it’s a bunch of other Australian researchers and it’s just cool, this penguin just jumps out of the water…
STEPH: Aw, I just saw it.
VINCENT: …onto the boat. It’s so cute!
STEPH: He’s so cute.
VINCENT: He kinda slips around and he’s looking for food probably.
CINDY: Yeah.
VINCENT: And then he gets scared and he jumps back in. But it’s so cool! I mean…
STEPH: Yeah.
VINCENT: Just jumps right out of the water he jumps back.
STEPH: Yeah that’s fun.
VINCENT: Anyways, so that’s cute. It’s the Australian…
STEPH: Yeah if you need a little mid-day break, that’s a good video.
VINCENT: …Australian Antarctic Division. Penguins are just awesome. I think they’re so cool.
CINDY: They are pretty cool animals.
VINCENT: Although I hear they smell.
CINDY: I think…yeah.
STEPH: Probably. Like most wild animals.
VINCENT: I heard if you go where they’re living and there are lots of them it smells really bad, but, they don’t really care about what we think they smell like I guess.
STEPH: Right. Fish and poop and fish and poop.
VINCENT: Exactly.
CINDY: Yeah.
VINCENT: So listeners, if you have picks you can send them in: Immune@microbe.tv, we’d love to have some, we have lots on all our other shows so…get with it. Get with the program. You can find us at microbe.tv/immune. You can find us on any podcatcher app, just slash, just search for Immune. And you’ll find, and please subscribe so you get every episode. Just one a month so it’s not so bad to do that and you’ll get em automatically. That helps us to know how many people are out there. And consider supporting us. Go to microbe.tv/contribute and you know, there are many ways you can help us out financially and they’re all listed there. Cindy Leifer is at Cornell University and on Twitter: @CindyLeifer all one word. Thanks Cindy.
CINDY: Thank you!
VINCENT: That was really good, I really appreciate that.
CINDY: It was fun.
VINCENT: Steph Langel is at Ohio State University. She’s on Twitter: @stephanielangel all one word. Thanks, Steph.
STEPH: Yeah, thank you this was great!
VINCENT: And I’m Vincent Racaniello. You can find me at virology.ws. I’m @profvrr on Twitter. The music on Immune is by Steve Neal. You can find his work at stevenealpercussion.com. Thanks for listening to Immune the podcast that’s infectious. We’ll be back next month.
{Music}