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Jan 10, 2022

Guest host, Dr. John Sweetenham, associate director for Clinical Affairs at UT Southwestern’s Harold C. Simmons Comprehensive Cancer Center and Dr. Syed Abutalib, medical director of the Hematologic Malignancies and Stem Cell Transplant Program at the Cancer Treatment Centers of America in Zion, Illinois, discuss advances in CAR T-cell therapy in the management of lymphoma, the toxicities associated with CAR T, and emerging bispecific antibodies for the treatment of lymphomas.



Dr. John Sweetenham: Hello, and welcome to the ASCO Daily News podcast. I'm John Sweetenham, the associate director for Clinical Affairs at UT Southwestern Harold C. Simmons Comprehensive Cancer Center and guest host of the podcast. I'm delighted to welcome my friend, Dr. Syed Abutalib, the medical director of the Hematologic Malignancies and Stem Cell Transplant Program at the Cancer Treatment Centers of America in Zion, Illinois.

He's also associate professor at the Rosalind Franklin University of Medicine and Science, and founder and co-editor of Advances in Cell and Gene Therapy. Today, we're going to be discussing some of the recent advances in the use of CAR T-cell therapy in the management of lymphoma.

Our full disclosures are available in the show notes, and disclosures relating to all episodes of the podcast can be found in our transcripts at Syed, it's great to have you on the podcast today. Thanks for coming.

Dr. Syed Abutalib: Thank you, John. It's my honor.

Dr. Sweetenham: Syed, the emergence of CAR T-cell therapy is having a transformed impact on the treatment landscape for hematologic malignancies in general, and for lymphoma in particular, and I'd like to give our listeners a sense of where we're at with CAR T-cell lymphoma. Can you tell us a little about the FDA approved agents which are now being used for the management of patients with malignant lymphoma?

Dr. Syed Abutalib:  Sure, so there are, at this time, about five agents that are approved based on mainly a phase 2 single arm study controlling them with the historical data from Scholar One in diffuse large B-cell lymphoma. They are axicabtagene ciloleucel. We'll be calling this axi-cel, which was approved after the data ZUMA-1 for the treatment of adult patients with relapsed/refractory diffuse large B-cell lymphoma after two or more lines of systemic therapy.

In this group, there were diffuse large B-cell lymphoma NOS, primary mediastinal large B-cell lymphoma, high grade B-cell lymphoma, and transformed diffuse large B-cell lymphoma from follicular lymphoma. The next agent that was approved was--let's see if I can pronounce it. It's the most difficult name--tisagenlecleucel which is tisa-cel was based on the JULIET trial. This drug was approved again for the adult patients with a relapsed/refractory large B-cell lymphoma after two lines of systemic therapy for the same indications as patients in ZUMA-1 trial except tisa-cel is not approved for the primary mediastinal large B-cell lymphoma.

The next agent is lisocabtagene maraleucel. We will call this liso-cel. This agent was approved after the pivotal trial TRANSCEND NHL 001. And the unique thing about this trial was also there were two patients with CNS lymphoma in this trial.

And again, the indications were similar to the axi-cel indication. And the fourth indication is for axicaptagene lisoleucel based on the ZUMA-5 trial, which was FDA approved for adult patients with relapsed/refractory follicular lymphoma after two or more lines of systemic therapy. And the last agent that has been approved is based on the trial of ZUMA-2, which is brexucabtagene autoleucel, brexu-cel. And this is approved for adult patients with relapsed or refractory mantle cell lymphoma.

Dr. John Sweetenham: Syed, thanks for providing that background. As you've shown, there are multiple agents which have been through early phase clinical trials. They've been applied to various subtypes of malignant lymphoma. And furthermore, they've been used at various stages in the treatment algorithm for these lymphomas, albeit mostly in the relapsed and refractory setting.

We've all been waiting for some time to start to see data emerging from prospective randomized trials of CAR T-cell therapy versus standard of care. And of course, we were exposed to some of the early data from these randomized trials at the American Society of Hematology Annual Meeting in December. And overall, there was the suggestion of a possible benefit to CAR T-cell therapy. Could you tell us a little bit about the data that caught your attention and your insights into how to interpret those data?

Dr. Syed Abutalib: Yeah, definitely. So as I alluded earlier, right now, the FDA approval is mainly for patients after two lines of therapy in diffuse large B-cell lymphoma. Now what is happening is that this CAR T-cell is trying to move forward into failure after first line of therapy. And in order to do that it is important that they have a comparative arm, which they tried to do in three trials by comparing it with so-called standard of care therapy. However, it must be noted that the standard of care therapy in diffuse large B-cell is not that straightforward for all patients who relapse. So just to give you the background, about 30% to 40% of the patients with diffuse large B-cell lymphoma experience relapse, and 10% are refractory to first line therapy. Now out of these patients, the standard of care therapy applies in real world practice as to the patients who are transplant eligible.

For the remaining patients who are transplant ineligible, there is no standard of care therapy. And the list is very long if you look at the NCCN guidelines for those patients. And the patients who are transplant eligible; if 100 patients go to transplant, 50% are cured. And there is a very good track record for this. And the ones who are cured are mainly the ones who are sensitive to chemotherapy, mainly platinum-based chemotherapy. So what these trials that were presented at ASH, one has to understand that what they call standard of care in their comparative arm because what happens is that if you have a comparative arm that is weak, that is not transplant-eligible patients, or the patients don't go to transplant, then your trial would look much better than what it really is.

So there were three trials that caught my attention. One is, of course, ZUMA-7, the axi-cel and the second one is the TRANSFORM trial with liso-cel. And the third one is the BELINDA trial, tisa-cel.  ZUMA-7 and BELINDA trial have been published in the New England Journal of Medicine already. So what is important to acknowledge here is that the patients in ZUMA-7 were refractory to frontline therapy.

About 74% of those patients were refractory, meaning that they did not respond to [INAUDIBLE]. Now we don't know how bad the refractory disease was, and ideally, these patients, if they are transplant eligible, which most of the patients were, would have gone to auto transplant, and 50% of them historically would be cured and the other patients who are relapsed within 12 months to frontline therapy. Now in ZUMA-7, they assumed that these patients who are early relapse will not respond to standard of care transplant.

They divided those patients to CAR-T versus transplant or non-transplant. The reason I say non-transplant, because only 36% of the patients who were on ZUMA-7 received what you call, ‘standard of care therapy,’ high dose chemotherapy with transplant. So I don't think it was a fair comparison to standard of care therapy. Now the other thing is the follow up is not too long as it is for the auto transplant. So it remains to be seen how things will evolve.

In the TRANSFORM trial, which was with the liso-cel, the large cell lymphoma group were either primary refractory or relapsed within 12 months. Again, they assume that the patients who relapsed early will not respond to platinum-based therapy. Ideally, these patients should go for auto-transplant.

In BELINDA trial, what is significant is that only 23% of the patients received auto transplant. And out of the three transplants, BELINDA trial was the only one which did not show improvement in median event-free survival compared to the standard of care. The hazard ratio was 1.01.

So it's difficult to say that these trials are truly positive for CAR-T over auto transplant because they did not compare auto transplant in the CAR-T. They compared all patients with relapsed or refractory disease who could have gotten transplant also to CAR-T, favoring the experimental arm.

Dr. John Sweetenham: Yeah, thanks Syed. So I think the take-home message that I'm hearing from you is that there are some interesting signals in these randomized studies about the potential efficacy of CAR-T. It's probably a little bit early to claim victory just yet, and we need to let these studies mature out a bit more and I guess ultimately wait for some overall survival endpoints.

You're absolutely right that there is still some uncertainty surrounding the interpretation of these results and the long-term effectiveness of CAR T-cell therapy. One thing there's no doubt about is that CAR T-cell therapy is associated with significant toxicities, the most common being Cytokine Release Syndrome and Immune Effector Cell Associated Neurotoxicity Syndrome, or ICANS. But of course, the list of adverse events is much longer. We recognize late toxicities, including prolonged cytopenias.

So right now, CAR T-cell therapy is mainly performed at larger tertiary care centers, but obviously, things are changing as regional facilities begin to do CAR T-cell therapies themselves. And even if they don't actually provide CAR T-cell therapy, a lot of physicians are going to be seeing their patients locally after they have developed toxicities from this treatment. How far have we come, do you think, in managing the toxicities of CAR-T, and how can we better manage those adverse events in our patients as we move forward and it becomes a more widespread intervention?

Dr. Syed Abutalib: I believe we are getting better in managing these therapies, but of course, the CAR T-cell therapy is at its infancy, and we are learning. In any case, it is important to understand what are the main toxicities-- as you had mentioned, the CRS and the neurotoxicity and the chronic B-cell achalasia or hypogammaglobulinemia, which basically reflects the persistence of CAR T-cell therapy. So, in an effort to improve on recognition and treatment of these side effects, ASTCT, which is the American Society of Transplant and Cellular Therapy, had the workshop in 2018 in Washington DC, and they published a paper subsequently in trying to educate everybody about these toxicities.

What is important in CRS is early recognition, and CRS is divided into different grades according to the ASTCT criteria from grade 1 to grade 4. Grade 1 is when you have fever. Many patients that we will admit or who we will treat who are very sick patients will get fever.

One should not assume that it is CRS. We should always exclude the infection and start the appropriate antibiotics. And as a transplanter, we are very well-aware of how to tackle this or as treating hematologic malignancies with a lot of neutropenic fevers. So, if you have fever, appropriate workup should be done.

Grade 2 ASTCT criteria is fever with hypotension that does not require pressors or hypoxia that requires low-flow nasal-cannula oxygen. Grade 3 is worsening of the hypotension, requiring pressors without vasopressin or hypoxia getting worse. And grade 4 is an extreme with multiple pressures requirement for hypertension and hypoxia requiring CPAP or BiPAP.

So all this requires close monitoring and one should also recognize the risk factors prior to the admission of the patient or prior to giving the CAR-T. What are the risk factors for this CRS. The risk factors, which include our high pre-infusion tumor burden, so it is important sometimes to debulk the patient.  Early onset of fever, presence of underlying inflammatory process or presence of infection--these things will help manage the CRS. The other thing is the neurotoxicity. And similarly, there has been criteria developed for that too.  There’s an algorithm at our institution, we have developed a card that has this criteria and algorithm imprinted on it. So, there is an ICE criteria which basically checks for patient orientation. And you have certain questions about ability to name three objects, following commands, writing, and attention. You give them certain points. And then you have them go into the neurotoxicity domain and check the level of consciousness and/or their seizures or motor findings or elevated cerebral intracranial pressures.

So based on that, you find out what is their neurotoxicity grade. Having said that, it is also important to have toci, which is IL-6 inhibitor, on hand. And according to the regulatory authorities, these drugs are approved under the REMS program. So you have to have at least two doses of tocilizumab in-house before you give any patient these drugs. So, to answer your question in a nutshell now is that close hemodynamic monitoring is very important, and it is important to have trained staff on board who can check on patients at regular, frequent intervals to recognize these toxicities early and intervene early to prevent morbidity and mortality.

Dr. John Sweetenham: Yes, thanks. And I think it emphasizes the fact that the initial patient selection for CAR T-cell therapy is extremely important bearing in mind not just the patient's disease state but also age, performance status, co-morbidities, and so on in the same way, really, as with transplant. I want to change gears just for a moment. There is no doubt that cellular immunotherapies like CAR-T remain of limited availability in part because of cost and effectiveness barriers. And without getting into a long discussion about that, I wonder if you could comment a little bit on other emerging therapies that in time could potentially, if it's the right expression, challenge CAR T-cell. I'm thinking in particular about some of the bispecific T-cell engaging antibodies which are now coming online.

Dr. Syed Abutalib: Sure. So the bispecific antibodies are basically protein constructs with a specificity to two different antigens. And they commonly bind immune effector cell antigens and tumor-specific antigens, creating what we call an immune synapse, which results in activation of the effector cells, which are T-cells, and cause direct cytotoxic activity. For example, we have an FDA-approved agent in ELL, and it's also listed in NCCN as an-- in transplant-ineligible patients, which is blinatumomab, which is a CD3 and CD19 construct.

Now in the clinical trials, there are many bispecific antibodies that are in development. The benefit of this is manifold, in my opinion. They are off-the-shelf immunotherapy.

They have strategies to mitigate CRS and neurotoxicities such as that they are given those adjustments with lower rates of doses early on and then the dose is escalated. And we see less CRS and neurotoxicity in patients. The third advantage is they might be preferable, especially in older adults.  I'm not sure if they are going to replace the auto transplant at this time. The other advantage is that there is data emerging that they are effective even after CAR T-cell therapy failures although the data is not mature yet. And still, we need them to be approved and see how they will be in the real world setting.

So some of them I will talk about. The one that really caught my attention was mosunetuzumab, which is called mosun. The unique thing about this is that it's IV, and there is a step up dosing to mitigate the CRS and neurotoxicity as I mentioned.  And it is a time limited therapy. It's not that you have to keep going, and that is important because of the cost effectiveness of the therapy. And this is a CD3 and CD20 construct. It is being tested in the third line follicular lymphoma as monotherapy in combination of Revlimid. The important thing is that the CR grade 3 and grade 4, very few patients, 2 patients out of 90 in follicular lymphoma, and no grade 4, grade 5 events occurred whether with monotherapy in follicular lymphoma with a CR rate of about 58%. They are also being combined with polatuzumab, which is an anti-CD79 antibody and also in relapsed/refractory diffuse large B-cell lymphoma as a subcutaneous dose because of, again, further trying to mitigate the CRS with a slow release form.

The other important biphasic antibody is glofitamab, which is being tested in relapsed/refractory follicular lymphoma, relapsed/refractory mantle cell lymphoma after BTKI, failures. And also, the data in more than 200 patients was presented in patients with diffuse large B-cell lymphoma, mantle cell lymphoma, transformed follicular lymphoma, Richter syndrome. So these two are very important to watch for.

There are others, such as epcoritamab, which is also C3 and CD20 bispecific antibody, which is also in a phase III trial, what is the standard of care in relapsed/refractory diffuse large B-cell lymphoma, and is also being tested upfront with R-CHOP. So I think these three are important to watch out for, and in my opinion, which might be incorrect, these are, as I alluded earlier, are more convenient, less laborious, can be less CRS, and might have about similar-- might have similar activity as CAR-T, might win the game over CAR-T. But it's too early to say. It's just an opinion.

Dr. John Sweetenham:  Thanks, Syed. And I think however this plays out, however, ultimately, these bispecific antibodies line up versus CAR T-cell therapy, I think two things are true for sure. The first of those is that patients with aggressive lymphomas and indolent lymphomas now have available to them a number of treatment options they didn't have before, which, of course, is great news. The second thing which is undoubtedly true is at least for a while, CAR-T therapy is with us to stay. Syed, it's been a pleasure having you on the podcast today and hearing your insights into how CAR T-cell therapy is evolving and its potential to improve patient outcomes in the future.

Dr. Syed Abutalib: Thank you, John.

Dr. John Sweetenham: And thank you to our listeners for your time today. If you enjoyed this episode, please take a moment to rate, review, and subscribe wherever you get your podcasts.



Dr. John Sweetenham:

Consulting or Advisory Role: EMA Wellness


Dr. Syed Abutalib: None Disclosed


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