Innovations in CAR T-Cell Therapy for Multiple Myeloma

Drs. John Sweetenham and Shaji Kumar discuss the emergence of CAR T-cell therapy for multiple myeloma, its benefits and challenges for patients, and its potential role earlier in the treatment of disease. TRANSCRIPT Dr. John Sweetenham: Hello, I'm Dr. John Sweetenham from the UT Southwestern Harold C. Simmons Comprehensive Cancer Center and host of the ASCO Daily News Podcast.  Multiple myeloma is the second most common hematologic malignancy, and the American Cancer Society estimates that there will be more than 35,000 new cases of the disease diagnosed in the United States this year. The emergence of several novel therapies over the last decade has transformed the therapeutic landscape for multiple myeloma, and chimeric antigen receptor – or CAR T-cell therapy – is one of the newest treatments for this disease, which has created a great deal of buzz.  Dr. Shaji Kumar is an internationally renowned investigator of novel therapeutics and next-generation treatment options for patients with multiple myeloma, and I'm delighted to welcome him to the podcast today to discuss innovations in CAR T-cell therapy in this space. Dr. Kumar is a professor of medicine and chair of the Myeloma Group, as well as chair of research in the Division of Hematology at the Mayo Clinic in Rochester, Minnesota. He is also the editor-in-chief of The Hematologist.  You'll find our full disclosures available in the transcript of this episode, and disclosures of all guests on the podcast are available at asco.org/DNpod.  Shaji, it's great to have you on the podcast today. Dr. Shaji Kumar: Thanks, John. Dr. John Sweetenham: Shaji, to begin with, maybe we could ask you for an overview of where CAR T-cell therapy sits in multiple myeloma right now. We know that CAR T-cell therapy has improved the survival for some patients with myeloma in recent years. But of course, relapse still remains a problem. Can you tell us a little about the therapies that are currently approved for multiple myeloma in the CAR T-cell space, and what are the potential benefits and challenges of these products? Dr. Shaji Kumar: Absolutely. It has been a revolution, I think, in terms of therapies for multiple myeloma during the past decade. We have seen so many new treatments approved for myeloma, and consequently, the survival of patients with myeloma has significantly improved. Two decades ago, we used to tell patients a median survival of 3 years, and today we tell patients a median survival of 8 to 10 years, a number that is continuing to go up. And it is all because of the new treatments that have become available for patients, especially over the past decade, and CAR T-cell therapy has been a game changer.   Now, the main treatments that we were relying on for the past 2 decades have been the immunomodulatory drugs, the proteasome inhibitors, and more recently, the anti-CD38 monoclonal antibodies. Unfortunately, what we see in the clinic is that patients go through these therapies and various combinations of these agents, and often over the 6 to 10 years after the diagnosis, they often become refractory to these drugs. And then we are left with very few choices, if any, for controlling the disease. And that's where the CAR T cells have really made an impact.  Over the past several years, clinical trials have shown that CAR T-cell therapy is highly effective. In fact, when we look at the initial trials that have been done in this space, the majority of these CAR T cells have been targeted towards what we call BCMA, or a B-cell maturation antigen that is present on both normal and abnormal plasma cells. Now, the concept of CAR T cells has been around for a while, and we have already seen success in other hematological malignancies, but it has been a little late compared to the other diseases in terms of its arrival in the myeloma field. But over the past few years, we have seen some dramatic progress. We currently have two different CAR T cells that are approved and available in the clinic. We have idecabtagene vicleucel (ide-cel) and also ciltacabtagene which is also called cilta-cel. Both of these CAR T cells are targeted towards BCMA.   In the early trials conducted with both of these CAR T cells, we’ve seen patients who have become refractory to all the available therapies, and now upwards of 90% of these patients are responding to these CAR T cells. We are now seeing responses that we had typically not seen previously in any of the other therapies – not only the high response rates but also the depth of response. What we are seeing is a significant number of these patients – nearly half – of these patients can actually be minimal residual disease (MRD)-negative in the bone marrow after the CAR T-cell therapy. And this is clearly unprecedented in this myeloma space. Now, the approval for both these CAR T cells has been based on the experience in patients who have become refractory to the currently available therapies. And the ‘line in the sand’ that the FDA has drawn for approval for these drugs has been at least 4 prior therapies. In those patients, when you look at the studies that have been done both for the ide-cel and the cilta-cel, it clearly demonstrates the advantages. And we can look at the data that's available in 3 groups. So we have the single-arm studies, the early phase I and phase 2 trials that have been done with both these CAR T cells. For ide-cel, we have the KarMMa trial, and for the cilta-cel, we have the CARTITUDE trials. In the initial studies, as I previously mentioned, we are seeing responses upwards of 90%, and we are seeing disease control that is lasting at least a year or more with these CAR T cells.   Now, of course, the question is, we do need randomized phase 3 trials to demonstrate that this is indeed true. Even before the phase 3 trials came along, there have been multiple case-control studies that have been done where the outcomes of patients getting these CAR T cells were compared to real-world controls or cohorts of patients who did not get these therapies. And these studies demonstrated that the outcomes of patients getting CAR T cells were significantly better than what has been shown in the real-world controlled population. And then finally, we have, of course, the phase 3 trials that have read out in patients with relapsed myeloma, in fact, in a group of patients in an earlier stage of the disease than who were studied in those single-arm studies. Now, based on the results from the single-arm studies, we got the approval from the FDA for the use of CAR T cells in this late stage of the disease. And with the phase 3 trials that have read out, both the KarMMa-3 trial and the CARTITUDE-4 trial again clearly demonstrate that these CAR T cells are much more effective than what we would have seen with the conventional therapies if those patients were assigned to those treatments. Now, clearly, it's not only a question of efficacy. We also know that they do come with some toxicities, and we have a good sense of the toxicities from those initial phase I and phase 2 trials. Now, as we have seen with the other diseases, the 2 major categories of toxicities that we see are the cytokine release syndrome and the neurological toxicity associated with CAR T-cell therapy.  In terms of the clinical features and the presentations, they are not different than what we have seen with the CAR T cells used in other hematological malignancies, but we do see different frequencies of these in the myeloma patient population. The cytokine release syndrome is something that is seen in a majority of the patients, at least in the lower grades. And over the time since we have been using CAR T-cell therapy, I think we have all become a lot more familiar with the management of the cytokine release syndrome, and we have very effective therapies to manage, and to some extent, maybe even prevent the onset of the cytokine release syndrome in patients undergoing CAR T-cell therapy.  The neurological toxicity is another toxicity that is unique to these immunological therapies, known as the ICANS, or the immune cell effector-associated neurological syndromes. And these, again, thankfully, are much less frequent than what we see with the cytokine release syndrome. But even with the ICANS and other neurological toxicities associated with CAR T-cell therapy, we have a better understanding of the biology behind it, and we also have better modalities to monitor the patients for these toxicities and intervene in an appropriate and timely manner to take care of them.  In addition to the ICANS and the cytokine release syndrome, we certainly do see other toxicities as well. We do see hematological toxicities, which are common for many of the treatments we use for hematological malignancies. Thankfully, these other toxicities can be easily managed. They often reverse themselves over time and haven't really posed any major hurdles in terms of the utilization of these modalities of therapy for patients with myeloma. Dr. John Sweetenham: Okay, that's great. Thank you very much, Shaji. I'll return to some of the potential late effects of CAR T-cell therapy in a moment. But before we get to that, as you know, in other hematologic malignancies, there has been a trend in recent years to moving CAR T-cell therapy further up the therapeutic algorithm, as it were. So there is consideration being given to using this as a first-line or second-line therapy. Do you think there is a potential role for CAR T cell earlier in the treatment of multiple myeloma? For example, could you see a time when it may be used as second-line treatment for this disease? Dr. Shaji Kumar: Absolutely. I think that's a very good point. And I think, just as with other cancers and as with myeloma, too, with many of the therapies we use for myeloma in the newly diagnosed setting or the time of first relapse, were all initially tested in these later relapses. We are following the same script even for the CAR T cells. In fact, the 2 phase 3 trials, the KarMMa-3 trial and the CARTITUDE-4 trial, enrolled patients in the earlier lines of therapy, either 1 prior line or 2 prior lines for these trials. And what we have seen with both phase 3 trials is that the outcomes, both the progression-free survival outcomes and the response rates, are significantly better compared to the standard-of-care therapies that these patients would have otherwise received.  Now, what is unclear at this point is, does every patient at the time of the first relapse need a CAR T-cell therapy, or can we be more selective in terms of deciding which particular subgroup of patients can benefit more from this CAR T-cell therapy in different lines or different relapses? The bottom line is, I think the data that we have right now clearly points towards the utility of CAR T-cell therapy at earlier lines of treatment. The question now is, which patients do we need to do at which stage? In fact, when you look at the newly diagnosed setting, there are ongoing clinical trials that are looking at replacing autologous stem cell transplant with CAR T-cell therapy. Those phase 3 trials are currently enrolling where patients are being randomized to either the autologous stem cell transplant, which is considered a standard of care for eligible patients, or giving them a CAR T-cell therapy. Similarly, even in transplant-ineligible patients, trials are exploring the possibility of using CAR T-cell therapy instead of giving patients a prolonged course of maintenance and consolidation.  One of the beauties with the CAR T-cell therapy right now is that it's a one-time treatment. You get the treatment and you do not get any additional therapies after that. It’s a protocol that is being debated – whether we will need maintenance therapies after CAR T-cell therapy, but I think that is something that will have to be explored in the context of clinical trials. But certainly, I think over the next 5 years, we will see the CAR T-cell therapy moving to earlier and earlier lines of therapy. My guess is in 5 years, there will be a subset of patients where we would offer them CAR T-cell as part of the first-line therapy, some others, maybe based on disease and patient characteristics, we might use it at the time of first or second relapse.   Dr. John Sweetenham: Great, thank you. Just to return to toxicities and some of the potential late effects. As you know, last November, the FDA launched an investigation to determine whether CAR T-cell therapy can, in rare cases, cause secondary cancers. You may remember that this was in response to reports of T-cell malignancies in patients who had received various types of CAR T-cell immunotherapies. The FDA determined that the risk of T-cell malignancies is applicable to all of the currently approved BCMA-directed and CD19-directed genetically modified autologous CAR T-cell immunotherapies. Could you care to comment on this whether you have seen any evidence of this in your own work, and whether the events and the FDA investigation have impacted your clinical research or your clinical practice in any way in terms of patient monitoring or maybe in terms of trial approval? Dr. Shaji Kumar: This has been an important observation. As with all new therapies, whenever the question of long-term toxicities is brought up, especially second malignancies, it is something that needs to be looked into very carefully, and I think the FDA is doing exactly that. There have been reports of second cancers, particularly T-cell cancers. In fact, there were some statements that came out recently from the FDA where they commented on the fact that they had seen 22 cases of T-cell cancers by the end of 2023. And, in fact, in 3 of those cases where genetic sequencing was performed, they did notice that the genetic material or the chimeric antigen receptor was inserted into these cancer cells as part of the process. So I think there is a lot more work that needs to be done in terms of understanding the mechanism and probably also understanding how prevalent these instances are.  But I think, based on what we know as of now, these cases form a very tiny fraction of the total number of CAR T-cell therapies that have been used in patients with lymphoma and myeloma. In our own day-to-day practice, this has not really affected how we view this therapy. It clearly has made a significant impact for patients with no other treatment options. So in our daily practice, we continue to use CAR T-cell therapy as we have done before these reports came out. But we do inform patients about the risk and what we know about the risk of these T-cell malignancies.   In addition to T-cell malignancies, there have also been reports of myelodysplastic syndromes in patients undergoing CAR T-cell therapy. Again, it is important to remember that, at least in the myeloma setting, many of these patients have had multiple lines of therapy, often with drugs that can cause second malignancies, particularly myelodysplastic syndrome. So I think a lot more work needs to be done in terms of understanding what is the direct impact of CAR T-cell therapy versus what was lurking underneath because of the treatments that these patients had previously received. So I think it is important for us to continue to be very diligent, as with any new therapies that we introduce for the treatment of our patients. But at the same time, understand that, in the context of the benefits that these therapies bring to our patients, especially when they have no other treatment options.  Dr. John Sweetenham: Absolutely. So, at least for now, and probably in the longer term, the benefits of the therapy certainly appear to outweigh the risks, although it is important not to underestimate or minimize those risks.   I wanted to change direction a little bit and talk a little bit in the final question about care disparities and CAR T cell. Of course, CAR T-cell therapy is typically offered at large cancer centers and is very expensive. This means that there are issues of access to treatment. In addition, the literature shows us that non-Hispanic Black individuals are twice as likely to develop multiple myeloma compared to their White counterparts. Furthermore, at least right now, Black patients are less likely to receive these novel CAR T-cell therapies and continue to be underrepresented in clinical trials. So, this is a big, complex question, but can you talk a little bit about how outcomes differ between racial and ethnic groups who actually receive CAR T-cell therapy for multiple myeloma? And could you address what you think are the most appropriate strategies for minimizing the disparities in access? Dr. Shaji Kumar: That's a very, very important question, particularly in the context of multiple myeloma, where African American individuals are at a higher risk of getting plasma cell malignancies. I think we need to think about this in the context of what we know about disparities even before the CAR T cell came along. There has been a good amount of literature that has looked at the outcomes based on the types of therapies that could be impacted by this. There have been studies that have looked at cooperative group trials, which often have a good representation of minorities and have shown that if patients have equal access to advanced therapies that we have, their outcomes are comparable or sometimes even better for African American patients compared to Caucasian patients. So I think it’s very important that the treatment strategies that we develop are equally accessible to everyone.  In terms of CAR T-cell therapy or immunotherapies, I don’t think we have any concrete evidence to suggest that there is any difference in outcomes. And I think it's reasonable to assume that if patients are exposed to similar therapies, they will have similar outcomes, even in the context of immunotherapies. But at the same time, I think we must continue to study this diligently, and the only way to do that is to ensure that clinical trials include patients reflective of society in general. This will allow us to understand if any differences exist. In addition, I think there is a serious risk that with these expensive therapies, this gap can only widen. And I think that is one reason that we must be proactive, particularly with therapies like CAR T-cell therapy, which not only are expensive but also require quite a bit of logistical support for patients to go to larger centers to get these therapies, stay around these larger centers for upwards of a couple of months, which means they are living outside of their usual societal structure, and ensure there is access to the resources that are needed to enable them to do that. So I think there is a lot that is still unknown, but I think we really need to be proactive in ensuring equal access to these therapies. Dr. John Sweetenham: Yes. Thanks for a very thoughtful response to that question, also for the work that you are obviously doing to help address this extremely important issue.  I’d like to thank you for sharing your insights with us today and for the extraordinary work that you’re doing and your team are doing to advance care for patients with multiple myeloma. Dr. Shaji Kumar: Thank you, John. Dr. John Sweetenham: And thank you also to our listeners for joining us today. If you value the insights you hear on the ASCO Daily News Podcast, please take a moment to rate, review, and subscribe wherever you get your podcasts.  Disclaimer:  The purpose of this podcast is to educate and inform. It is not a substitute for professional medical care and is not intended for use in the diagnosis or treatment of individual conditions. The guests on this podcast express their own opinions, experience, and conclusions. Guest statements do not necessarily reflect the opinions of ASCO. Mention of any product, service, organization, activity, or therapy should not be construed as an ASCO endorsement. Find out more about today’s guest:    Dr. Shaji Kumar @myelomaMD   Follow ASCO on social media:       @ASCO on Twitter    ASCO on Facebook    ASCO on LinkedIn       Disclosures:      Dr. John Sweetenham:   Consulting or Advisory Role: EMA Wellness     Dr. Shaji Kumar: Consulting or Advisory Role: Takeda, Janssen Oncology, Genentech/Roche, Abbvie, Bristol-Myers Squibb/Celgene, Pfizer, Regeneron, Sanofi, K36 Research Funding (Inst.): Takeda, Abbvie, Novartis, Sanofi, Janssen Oncology, MedImmune, Roche/Genentech, Carsgen Therapeutics Ltd., Allogene Therapeutics, GlaxoSmithKline, Regeneron, Bristol-Myers Squibb/Celgene Travel, Accommodations, Expenses: Abbvie, Pfizer