From Lab to Life: Expanding the Power of CAR T-Cells

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Daniel Simon, MD: Thank you for listening to another episode today. I am happy to be joined by two guests. Dr. David Wald and Dr. Reshmi Parameswaran. Dr. Wald is the John Chrisman and Francis Drake, professor of Pathology at Case Western Reserve University School of Medicine, the co-director of the Immune Oncology Program and the Case Comprehensive Cancer Center, and the Director of Histocompatibility and Immunogenic Lab at University Hospitals Cleveland Medical Center. Remi Parameswaran is the Director of Cancer Biology training program at Case Western Reserve University; she is an associate professor of medicine in the Department of Medicine at Case Western Reserve University. Welcome.

Reshmi Parameswaran, MS, PhD: Thank you.

David Wald, MD PhD: Thank you.

Daniel Simon, MD: Well, it's great to have you here today. These are really two of the gems of research in the Seidman Cancer Center at University Hospitals, Seidman Cancer Center and at Case Western. We are going to learn a lot from them today about CAR T therapy. But before we start there, it's always great for us to learn a little bit about each of you, where you're from, how you got here and your journey. And, Reshmi, perhaps we can start with you because it's so interesting that I noticed that you went from India to Israel. So, tell us a little bit about your background.

Reshmi Parameswaran, MS, PhD: Sure. Absolutely. So first, thank you for inviting me to this podcast and my journey is from east to west and started in India in a small state called Kerala, and I did undergrad and masters in biochemistry there. And then moved to Israel for PhD at Wiseman Institute of Science. At Wiseman actually, I got introduced to cell therapy and I was fortunate to work with many of the scientists there, including Dr. Zelig Eshhar who is the inventor and father of CAR T. And all students were motivated by that discovery. And from there I moved to Los Angeles for my postdoctoral fellowship in Children's Hospital Los Angeles. And there I was working on a protein called BAF, B-Cell Activating Factor.

And the receptors of BAF actually works, it's expressed on almost all B cells, normal B cells as well as cancer B cells and also autoimmune B cells. So, I was thinking of targeting these receptors will be a real attractive strategy for treating many of the diseases. And when I moved to Case Western as a faculty and started my own independent lab in 2016, I was thinking of making a CAR with targeting BAF receptors, and that's when I met Dr. Zelig Eshhar in a conference in Melbourne, and I was discussing with him about this idea and I told him, see, I don't have antibody sequences for these receptors because for a conventional CAR approach, you need antibody sequences, and I think, like me, most of the PIs who want to target many proteins or antigens they don't have access to these antibody sequences.

So, then I thought about, what about using a natural ligand in a CAR? Because the whole idea is cancer cells should come and bind to CAR T-cells, and CAR T-cells should attack them. So, it's all about binding.

So, I thought, why not use a natural ligand or extracellular sequence of a ligand. And I discussed this with Dr. Zelig Eshhar and he said, why not you just try, then only you will know. So, then we started trying, and of course that worked very well in all the preclinical B-cell cancer models. And right now, it's in four clinical trials for three different cancers and for autoimmune lupus. So here I am with, now my lab is focusing on cancer immunotherapy strategies, CAR T and CAR-NK for solid cancers as well as autoimmune diseases.

Daniel Simon, MD: David, a little bit about how you got to where you are today.

David Wald, MD PhD: Sure. First, thank you so much for the opportunity to talk about our work today. Excited to be here.

So actually, my kind of journey started in Cleveland. I was born in Cleveland, kind of from a very early age, I knew I wanted to discover new therapies and work on therapeutic development. My grandfather was a pharmacist, and I think my passion for that came from interactions with him early on, but I didn't know what that involved or where that would take me. And then, I went to college at Cornell University and when I left for college, I never, in my wildest dreams thought I'd end up back in Cleveland, but then I came back for the MD PhD program here, did a pathology residency, and I still never thought I would end up in Cleveland. But I am here today and I think it's one of the best decisions I've ever made. I just kind of fell in love with the infrastructure, had such great support from the institution and I never left.

When I did my initial research training, I worked in the area of immunology.  And then during my clinical rotations, I really developed a deep interest in cancer just seeing cancer patients, going through chemotherapy with all the horrible side effects and just seeing there's so much unmet need for patients with relapse through refractory malignancies. And so, the early half of my career was focused on drug development on the small molecule therapeutic side. And actually I have to thank Reshmi partially for my transition into cell therapy because I had the opportunity to work with her when she first came to Cleveland and she was working on NK cell projects and that really opened my eyes to cell therapy and since then, now my lab has been focused on NK and, and CAR T therapies primarily.

Daniel Simon, MD: Well, you know, it's just great to hear about those paths. I mean, they're very circuitous. But the great thing is, is that we have both of you here.

I think for our listeners, many don't realize that Cleveland has a lot of prominence in cell-based therapies, the mesenchymal stem cell was discovered by Arne Caplan of Case Western, and Stan Gerson's real drive into cell-based therapies was responsible for us being named the National Center for Regenerative Medicine with tremendous investment, both from federal sources as well as state sources. And, we have this amazing cell production facility that allows us to really flourish in this space. So, we owe so much to others as well. But we're here to talk about two of our stars today.

Now, to set the stage for all of this, I think maybe both of you could just comment a little bit-- the idea of leveraging our own immune system to attack cancer is very commonly held now. But it always hasn't been that way. We know that cancer is very good at cloaking itself from the immune system, but perhaps you could tell us to set the stage for eventually talking about CAR T. How is it that potentially our own body can be leveraged to fight cancer?

So maybe, Reshmi, we can start with you.

Reshmi Parameswaran, MS, PhD: Yeah, sure. So, our immune cells always have the capacity to fight with cancer cells and kill cancer cells, and mostly two types of lymphocytes play important role like T cells and NK cells. And both of these cells are really good at doing their job, but obviously we know people get cancer. Why? Because these cells either become dysfunctional in patients or they cannot do their job because of some other factors around them, some other proteins surrounding them makes them dysfunctional.

So sometimes they cannot do their job to their best, and that is where this adoptive cell therapy comes to play. So, we have to take blood from patients, take the immune cells out like T-cells or NK cells. And in CAR T therapy especially, we are making them more active and giving them more specificity. So, we are telling these immune cells or T cells especially to go and kill only cancer cells and spare the normal cells. So that's the specificity part. And, for safety in terms, you know, it's our own or patient's own, immune cells. So, safety-wise also, it's not a big problem. So, using a patient's own immune cells, I think it's very attractive, especially in CAR T field we are giving them specificity as well. And also, we can expand them ex vivo in a large number because in patients they will not have enough number of T cells. So, we can expand these cells, cells in millions, ex vivo, and then give them large numbers of CAR T-cells. So, all these ways I think CAR T-cells are really promising.

Daniel Simon, MD: So, David, a little bit from you on a little of the cancer cloaking properties and how we can, at least through drugs as well, PD inhibitors and others, try to allow our own cells before we engineer them to do their thing too.

David Wald, MD PhD: Yeah, so, tumors are very smart. They try to evade the immune system. That's why initially they're able to progress is because they develop strategies to evade them, either make them dysfunctional as Reshmi mentioned, or to evade them or block them. And so, for example, when we infuse T cells into patients there's one of the initial issues with trafficking into the tumor. So, tumors create barriers for the T cells to even enter the tumor. They can do this physically; they can create factors that they secrete. One of the dominant factors is called TGF-beta, for example, and that causes dysfunction of the immune cells and modifies their trafficking receptors that prevent them from actually entering the tumor. And so, strategies that people are trying to develop to improve the trafficking, I think is one key element, and also once they get into the tumor, then tumors have a lot of different strategies by modulating the metabolism, by making a very hostile environment for the T-cells to maintain that activity and so using factors, for example, interleukin 15 cytokines that could boost the activity of these immune cells can help to overcome that as well.

Daniel Simon, MD: That's great. So, I think, we've seen from the days when I was, treating cancer patients as a resident, it was all chemotherapy. And of course, now immunotherapy makes up at least 40 to 50% of treatment protocols for patients. So, it's a complete revolution.

So alright, we've talked about CAR T-cells and now we have to get really basic here. What is a CAR T-cell? How are they manufactured? I know, David, you're really focused on speeding up that manufacturing process. Take us through what is a CAR T-cell, how we make them, and then what is it that you've done to try to speed up this process so we can treat patients in a more timely manner? So, David, why don't you start.

David Wald, MD PhD: Sure, and so CAR T-cells are essentially a genetically engineered T-cell and so you have to get a starting cell source. It could come from a variety of different areas, it could be an autologous product, which are all the FDA-approved products or autologous products. For all those products you start with what's called an apheresis sample. So, it's a large collection of essentially mononuclear, white blood cells. There are methods now to use peripheral blood or stem cells, as well if you want to make allogeneic or off-the-shelf therapies. But essentially you need a source of the T-cells. And then you take them into a GMP facility, which needs to be a very specialized facility with specific air handling requirements and procedures to be able to produce this in a sterile fashion that's safe for patients. And then you essentially need to introduce the CAR, the chimeric antigen receptor gene into the T cell.

Most commonly that's done by an antiviral vector-based approach. But there's other approaches like electroporation and transposons, lip and nanoparticles and other ways you can introduce that genetic material into the T-cells. And then historically, it was thought that you needed large numbers of these cells to see significant efficacy. So they were expanded into billions of cells in the lab over a course of one to two weeks and then infused into the patient. And kind of what we've been working on is trying to, to shorten that process and trying to prove that you don't actually need as many cells to get good outcomes.

Daniel Simon, MD: So, Reshmi, it's very complicated. And you already talked about some really interesting tricks that you did, as you said, to attract the cells by having multiple ligands present. This is all done in the lab now, but there's this promise, potentially, that we can do these and make these CAR T-cells all in vivo that we won't need to take them out. So that, although you've accelerated the manufacturing David to maybe quality control and release in a week as opposed to four to six weeks for commercial products it would be great to be able to make them in the person themselves.

So, Reshmi, tell me a little bit about what's in that space right now.

Reshmi Parameswaran, MS, PhD: When we talk about CAR T manufacturing, like David said, he has the ultra-fast manufacturing, which shortens the time of manufacturing as well as the cost. But there are other features like we have to consider CAR designs, which increases the CAR T persistence in vivo in patients. So certain designs we already optimized so that they increase the persistence of CAR T's inside patients, as well as we can, activate the CAR T cells by using certain designs. So, we are in an era of optimizing all these designs, and scientists already have done that part.

So, the next era, as you said, is all about in vivo CAR, giving them like mRNAs, LNPs, like nanopore particles with mRNAs. And then it’ll just go and infect patients' T-cells and all the process we did outside the body will happen inside the body. And then that will again shorten the wait for, especially for terminally ill patients; these three weeks' wait is a lot. So that will shorten the wait and probably reduce the cost of CAR T therapy.

So, there are other CAR T therapies coming now. We are now in a fourth-generation CAR Ts era, and fifth generation is going to come. So, we have many different armored CAR Ts where they use extra cytokine receptors, which help their persistence as well, and proliferation. And there is recently antiquated CAR Ts, where we use two CAR Ts. Only, so if it binds to two antigens, it'll work, so that will reduce off target effects.

So, there are so many attractive CAR Ts coming up, which will really help. And one of the CAR Ts I mentioned is ligand-based CAR T, which I developed, and is based on a natural protein sequence which will really help for multi-receptor targeting. So, antigen escape is a big problem in the field of CAR T therapy. So multi receptor targeting, most probably I assume, or I hope it'll help escape that antigen loss phenomena.

Daniel Simon, MD: It's incredibly exciting when you say we're already in fourth generation, but take us back just a little bit, David and Reshmi, to okay, intentionally you went after blood cancers, as we call it, easy accessibility, started in lymphomas in multiple myelomas. Tell us why is that an attractive place to start? And then what are the challenges on the other side for solid tumors? So why did we start with lymphomas and blood cancers?

David Wald, MD PhD: Well, I think, the efficacy is significantly higher, clinically, and I don't know that we entirely know all the reasons for it, but it just works very well. I have my own kind of ideas of why it works well for lymphomas, for example, because you have normal B cells, the CAR T cells are actually killing the normal B cells as well. But people, surprisingly, could survive quite well without normal B cells and contrast for solid tumors.  You don't have the same targets that are very specific to solid tumors in many cases where they're not on at least a subset of normal cells. And typically, those can get very high toxicities when you start to see high efficacy. And you really need the kind of, at least in the B-cell context, you need the full elimination of normal B cells to see the strong efficacy. And so, I think, you know, a selection of targets has been very challenging with solid tumors. The tumor microenvironment is also quite different with solid tumors versus blood cancers. And I think that makes it easier to see efficacy with blood cancers as compared to solid tumors.

Daniel Simon, MD: So right now, we use CAR T cells in lymphoma for lymphomas that have failed, standard therapies and you hear stories of patients who've failed four, five different regimens who come in and it's their last hope, and yet you're able to get them into complete remission. Are there efforts underway to use CAR T upfront as first-line therapy in trials now?

David Wald, MD PhD: Yes, there are trials for upfront treatment getting approvals at lower and lower lines of therapy. We're actually having discussions with some oncologists at our center. We really like to do a trial for particularly patients who you know that they're just not going to respond to chemotherapy. There are patients with very aggressive, very, poor, high-risk, outcome patients. You're having them treat chemotherapy knowing it's not going to work. It'd be better to try a CAR T therapy. And so, we've been in discussions with some of the oncologists here. Maybe we could start something in the future at UH to specifically look at that in a subset of patients.

Daniel Simon, MD: So, Reshmi, how did you migrate to multiple myeloma and then from multiple myeloma to one of the most resistant cancers that you would ever treat, which is osteosarcoma. You know this cancer affects adolescents and young adults that like pancreatic cancer. We've just not seen major advances in our medical lifetimes. So how did you go from multiple myeloma to osteosarcoma?

Reshmi Parameswaran, MS, PhD: Yeah, so that's a good question. I, like I told you earlier, worked with a protein called BAF for about 20 years. And that receptors of BAF are present on multiple myeloma, so especially BCMA and TACI, two receptors of BAF are present on multiple myeloma cells. And we can target those two receptors at a time using BAF CAR T. That is why we started with multiple myeloma, because CD-19 CAR T, which is FDA-approved right now. It is not good for multiple myeloma treatment because multiple myeloma cells lack CD-19. So that's a good strategy to target two other receptors, BCMA, and TACI using BAF CAR T. So that's how we started with multiple myeloma and coming to osteosarcoma, it's a total different story. It's a solid tumor. Lot of challenges waiting there, and we were looking for tumor specific markers, tumor specific antigens, and Oncostatin M or OSM is one such protein where its receptors are expressed on most of the solid tumor cells. So, when we looked at the database, we found that osteosarcoma cells express actually both of its receptors, OSM receptor, and LIF receptor. So, then I thought, okay, that's a good idea. Let's take OSM, let's make OSM CAR T first and try to deal with osteosarcoma, and surprisingly, it was really surprising to see in mouse models these osteosarcoma tumors were totally like gone, like disappeared in a matter of four days. So that was really surprising because how these CAR T-cells endured that solely tumor compartment and kill the tumor cells. So that's how we started the study. And then we found that very interesting observation. That is some CAR T-cells can kill cancer associated fibroblast.

So, the solid tumors have a solid structure which makes it difficult for the CAR Ts to infiltrate into the solid tumor cells. So, cancer associated Fibroblast gives it a solid structure and OSM CAR T actually targets the cancer associated fibroblast because under chronic inflammation or under cancer, the OSM receptors are really upregulated in cancer associated fibroblast as well as in tumor cells. So, we are not only targeting tumor cells, we are targeting the microenvironment as well. So, once it kills that fibroblastic structure, it can enter and find the way into the tumor cells and kill them. So that's the advantage of these CAR T for osteosarcoma, and that's why we started with osteosarcoma because of databases showing a good expression of the receptors.

Daniel Simon, MD: I have a question, so, in at least liquid tumors, lymphoma tumors, you have the circulation, the bone marrow, lymph nodes, there's access in solid tumors. As you pointed out, there are a lot of protective mechanisms, but there are issues of getting sufficient number of cells there. So that has led to, for instance, in glioblastoma local therapy into the ventricles through a pump and things like that. Is there data that you are going to need both systemic and local therapy? Where does that sit right now?

Reshmi Parameswaran, MS, PhD: So, there were many CAR T strides for osteosarcoma.  for example, B7-H3 CAR T, GFR CAR T, et cetera. But all of them were not big success yet because these CAR T-cells have to find their way to the tumor and it has to enter the tumor. So that is the main challenge. That's why I said because OSM CAR T at least kills those fibroblastic solid structure, we are assuming that it'll find its way to the tumor cells exactly the way it worked in mouse. We are expecting that it'll work in human, but mouse are mouse and human are human. We never know, but at least that is the advantage we are seeing for our CAR-T, like targeting that solid structure and finding its way to the tumor.

Daniel Simon, MD: So, you've talked a little bit about NK cells which are called natural killer cells for our listeners, and there is something called CAR-NK. What is a CAR-NK cell? How is it different than a CAR T-cell and where are you using them now? So maybe David, you could start.

David Wald, MD PhD: CAR-NK are similar to CAR T-cells in terms of that it's, you know, an NK cell instead of a T cell. But they express chimeric antigen receptors, and so there's been a lot of work done, for example, on CD-19 CAR-NK cells, there's certain advantages and disadvantages of NK cells. Disadvantages are they don't persist very well in vivo; they don't expand as well and so you see more of a transient effect. The advantages are they could be used as universal donor.

So, we've done several trials at University Hospitals using what are called our universal donor off the shelf NK cells. And so, it's much cheaper to make, they can be accessible anytime because they're just frozen. They just need to be thawed and infused. And so, we've done a little bit of work with CAR-NK cells, for some solid tumor targets in particular, in our kind of head-to-head testing of the CAR-NK versus CAR T, we just see much better efficacy with the CAR T-cells.

And so, I think for cancer therapy now the field is moving a little bit away from NK cells and more towards T cells. A lot of autoimmune, non-malignant conditions, there's still a lot of effort in NK cells, but a lot less than there was a few years ago. But I think in the future, you know, if there's more strategies developed and more mechanisms understood to get better persistence and expansion of NK cells in vivo, that could again shift, shift very rapidly.

Daniel Simon, MD: It's interesting you talked about this ability to using lower number of cells and have more stemness. So, these cells are persistent and surveilling cancer from coming back is a very interesting thing because it's almost like you, you've got someone on your team knocking the cancer down, for years, so to speak. So, what is the evidence that CAR T-cells are persistent for? How long? How long are they there?

David Wald, MD PhD: Yeah, that's a good question. I think no one knows for sure, but they have been measured,10 years out in patients. And so there are examples where they could potentially persist forever. But definitely, months to years is typical, at low levels. And then when you know the tumor starts to come back, you can actually see in patients that these CAR T-cells are re-expanding again. And I think you really need that persistence for long-term durability. And that's where NK cells may, may actually be used in conjunction with CAR T-cells, for example.  if the patient needs to be really treated very quickly, maybe you give a dose of NK cells to control the disease while the CAR T-cells are being prepared and give maybe longer-term durability.

Daniel Simon, MD: That's very interesting. So, Reshmi, you mentioned a little bit about autoimmunity and non-cancer indications. So, my lab happens to also study lupus or systemic lupus erythematosus, SLE, affects predominantly women and can be a devastating autoimmune disease that affects, the kidneys, lungs, skin, CNS, thrombotic complications.

Very exciting data in CAR T and lupus. Tell us a little bit about that story. Because I know that you're very interested in autoimmunity as well.

Reshmi Parameswaran, MS, PhD: Yes, we have done some good work in autoimmune lupus in mouse models, and we published it recently as well. So, we are seeing actually very good efficacy of these BAF CAR T-cells killing the autoreactive B cells. So that obviously will reduce the antibody production. And most of the symptoms were disappearing in mice, at least we checked proteinuria in these mice, we checked auto antibodies, we were weighing them, we were measuring, looking at the hair loss. So, all these symptoms actually became better after the BAF CAR T treatment. And fortunately, now BAF CAR T entered clinical trial for lupus in Columbus and first couple patients already treated. And we are hearing very exciting news that they went into remission, after one month. That's great news. So yeah, I'm really looking forward for taking BAF CAR T for other autoimmune disease as well because the whole mechanism is all about killing the autoreactive B cells. So, we are right now working on rheumatoid arthritis and autoimmune type one diabetes, and we are also working on scleroderma models as well.

Daniel Simon, MD: How exciting I think the one thing that I've learned today is that we must have you back in 24 months, the pace of change here is just remarkable. I think that we're very excited, Reshmi, that potentially you'll be able to move osteosarcoma into patients, you know in the not-too-distant future. And we know, David, we're already following your amazing results with your ultra-fast preparation and your presentations that have been seen worldwide at ASH. So, congratulations to you.

I want to thank both of you for joining me today. Thank you to our listeners.

To learn more about research at University Hospitals, please visit UHhospitals.org/uhresearch.

Thank you, Reshmi and David.

Reshmi Parameswaran, MS, PhD, and David Wald, MD, PhD: Thank you.

Conflicts of Interest: Dr. Wald is the founder of Kure Cells that is developing CAR T-cell therapies. Dr. Parameswaran is a scientific advisory board member for Luminary Therapeutics.

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