The Future of Maintenance Therapy for Multiple Myeloma

Dr. John Sweetenham and Dr. Marc Braunstein discuss the role of maintenance therapy in high-risk multiple myeloma, advances in myelodysplastic syndromes in the COMMANDS study, the promise of bispecific antibodies in the pivotal EPCORE NHL-1 in relapsed/refractory large B-cell lymphoma, and improving outcomes for patients with chronic lymphocytic leukemia in the CAPTIVATE trial.

TRANSCRIPT

Dr. John Sweetenham: Hello, I'm Dr. John Sweetenham, the associate director for cancer network clinical affairs at UT Southwestern's Harold C. Simmons Comprehensive Cancer Center, and host of the ASCO Daily News Podcast. My guest today is Dr. Marc Braunstein, a hematologist and oncologist at the NYU Perlmutter Cancer Center. Today, we'll be discussing key posters and oral abstracts highlighting advances in hematologic malignancies that will be featured at the 2023 ASCO Annual Meeting.

You'll find our full disclosures in the transcript of this episode, and disclosures of all guests on the ASCO Daily News Podcast are available on our transcripts at asco.org/DNpod.

Dr. John Sweetenham: So, Marc, thanks for returning to us and coming to join us on the podcast today.

Dr. Marc Braunstein: Thanks for inviting me back.

Dr. John Sweetenham: I'd like to start out with Abstract 8001. This is a study which is addressing the role of maintenance therapy in patients with high-risk multiple myeloma. Could you take us through this study and the key take-home points that you think are the most important ones?

Dr. Marc Braunstein: Sure, absolutely. So, the first abstract that we're going to discuss is an oral abstract being presented by Dr. Nooka regarding maintenance therapy in high-risk multiple myeloma patients. Outcomes of patients with multiple myeloma are clearly improving, yet those with high-risk cytogenetic abnormalities, which represent about 10-20% of all multiple myeloma, tend to have poorer survival, and worst among these are those with what's called ultra-high-risk or double-hit multiple myeloma who have more than 1 high-risk cytogenetic abnormality. So, this study looked at maintenance therapy following stem cell transplantation in 26 high-risk patients, about 59% of whom had double hit disease, representing very high-risk disease. This was a phase II study looking at using carfilzomib, pomalidomide, and dexamethasone in high-risk multiple myeloma patients who achieved at least a partial remission following stem cell transplant.

There were 26 patients enrolled. The median age was 60. Of note, about 59% of patients were Black, which is important because these patients tend to be historically underrepresented in studies. And what they found was that at study entry, about 24% of patients were in a complete remission or better, and that deepened to 79% while on the study. And the median time to best response was 2 months, which is fairly brisk. With a median follow-up of about 26 months, the 36-month progression-free survival was 63%, and the overall survival was 72%, which is impressive, again in the context of patients who have very high-risk disease. So, although it remains to be determined what the optimal regimen or duration of maintenance should be in multiple myeloma, clearly, combination therapy is effective and should be used in patients who have high-risk or ultra-high-risk multiple myeloma.

Dr. John Sweetenham: Great. Thanks, Marc. So, as you say, I mean, clearly the take-home message is around the effectiveness of this type of maintenance therapy. I just have a couple of quick follow-up questions for you. The first of those is, where do you see this going next? I mean, in your opinion, what would be the next logical study with this combination or similar combinations? And then secondly, what do you see on the horizon for those patients with very high-risk myeloma, particularly the double-hit population that you just mentioned?

Dr. Marc Braunstein: It's a paradigm in multiple myeloma that combination therapy tends to be more effective as long as we're able to manage the adverse events that come with additional combinations. And we've been able to succeed in that regard with quadruplet regimens, even now that we have monoclonal antibodies that tend to be better tolerated and more targeted in nature. In terms of maintenance therapy, single-agent lenalidomide has been the long-standing agent of use for the majority of patients. But we now understand that the combination of an immunomodulator like lenalidomide and a proteasome inhibitor like bortezomib or carfilzomib is more effective for patients with higher risk disease.

We also have data from various upfront studies of quadruplet regimens, such as the FORTE study, which looked at carfilzomib and lenalidomide maintenance after transplant that shows that we can improve progression-free survival in all comers with multiple myeloma following transplants. So, I think down the road we're going to be looking at more use of combination therapies and maintenance. And as far as for high-risk patients, whether that's going to be using monoclonal antibodies in maintenance or combination proteasome inhibitors and immunomodulators or even other immunotherapies like bispecific antibodies as maintenance in the future remains to be determined, but clearly, for high-risk patients, we should be using combination therapies.

Dr. John Sweetenham: Thanks, Marc. Let's change gears a little now and take a look at Abstract 7003, which addresses patients with myelodysplastic syndrome. This study addresses the efficacy and safety results from a study of luspatercept versus epoetin alfa in low-risk myelodysplastic syndrome. I wonder if you could describe this study and the results to us and maybe also for the benefit of our listeners, just mention quickly the mechanism of action of the experimental agent here.

Dr. Marc Braunstein: This is an oral abstract being presented by Dr. Garcia-Manero looking at a phase 3 study, as you mentioned, called the COMMANDS study, and this is looking at an agent called luspatercept in patients with low-risk myelodysplastic syndrome (MDS). So, patients with MDS can have inferior quality of life and survival when they become transfusion dependent. An earlier study called the MEDALIST study, which was published in the New England Journal of Medicine in 2020, randomized low-risk or intermediate-risk patients with MDS who were refractory or unlikely to respond to erythropoietin stimulating agents to either luspatercept, which is an agent that binds to TGF-beta family members and helps stimulate erythropoiesis. Patients were randomized in the MEDALIST study to luspatercept or placebo. And that study showed that luspatercept could improve a degree of anemia and lead to transfusion independence in certain patients.

So, the COMMANDS study is a randomized controlled study that randomized 354 patients with low-risk MDS who were transfusion dependent and naive to an erythropoietin stimulating agent to receive either luspatercept or the erythropoietin stimulating agent erythropoietin alfa with the primary endpoint of transfusion independence at some time between 12 to 24 weeks. So, patients were randomized 1:1 to receive either luspatercept or epoetin alfa, and the primary endpoint again was transfusion independence. So, 354 patients were randomized in the study and the median treatment durations were 42 weeks of luspatercept and 27 weeks of epoetin alfa. And transfusion independence occurred in greater quantity in the patients who got luspatercept. For example, in the patients who received luspatercept at 8 weeks, transfusion independence was achieved in 74 versus 51% in the epoetin alfa group. So, in terms of treatment-related adverse events, they were fairly similar between the groups and consistent with the classes - they were reported in 30% in the luspatercept group and 17% in the erythropoietin group, with no difference in patients who progressed to acute myeloid leukemia.

So, I think when it comes to MDS in low-risk patients, it's really important to preserve their quality of life by limiting their transfusion burden. And I think this study demonstrates that luspatercept continues to be an important part of the management in these low-risk patients. And whether or not you would start a patient with low-risk transfusion-dependent MDS on an erythropoietin stimulating agent or luspatercept is really addressed by this study showing that you can achieve greater rates of improvement in anemia and transfusion independence with luspatercept.

Dr. John Sweetenham: Great. Thanks, Marc. A really interesting study. And I do have one question for you about this study, which I think will make it clear to you that I am an expert neither in myelodysplastic syndrome nor in erythropoiesis. But my question is based on the mechanism of action. Is there any rationale for combining these 2 agents in future studies?

Dr. Marc Braunstein: Yes, it would potentially make sense to use 2 synergistic mechanisms to improve erythropoiesis. We would have to see what the potential for adverse events are. I think epoetin alfa tends to be a fairly low burden in terms of its side effect profile. Luspatercept can have some potentially dose-limiting side effects, such as GI side effects, but you can make dose adjustments to both of these medications. So we may need to find the correct doses of either of them in combination. But from a theoretical standpoint, it makes sense that these could potentially be synergistic, especially in patients who are likely to respond to erythropoietin by having a baseline lower erythropoietin level.

Dr. John Sweetenham: Okay, let's move on in another change of gear now. And for the rest of the podcast, we're going to be talking about some studies in lymphoid malignancy, beginning with Abstract 7535, which is a follow-up of the phase 2 CAPTIVATE study which now has significantly extended follow-up from the original report. So Marc, can you walk us through this study and the outcomes to date?

Dr. Marc Braunstein: Absolutely. So this is a poster being presented by Dr. Barr and it is looking at CLL, which is a field that is really moving away from chemotherapy for newly diagnosed patients, thanks to the development of novel targeted agents. The CLL14 trial, which was published in the New England Journal of Medicine in 2019, showed that fixed-duration venetoclax plus obinutuzumab improved progression-free survival and rates of negativity of minimal residual disease, or MRD, when compared to chlorambucil and obinutuzumab. So building on the success of that study, combining a monoclonal antibody and a BCL2 inhibitor, the CAPTIVATE study is a phase II study, which examines venetoclax with ibrutinib, the BTK inhibitor, and previously untreated CLL. So it's kind of combining 2of the novel targeted therapies in a fixed duration, similar to what was done in the CLL14 study where patients received 1 year of therapy and then stopped treatment.

So in the CAPTIVATE study, 154 patients were enrolled. This was a phase 2 study that included about 56% of higher-risk patients who had unmutated IGHV, and the median time on the study was 50 months, with a CR rate of 58% at a 4-year follow-up and an overall response rate of 96%, which is quite high, especially considering that more than half of patients had high-risk disease. The progression-free survival was 79% and the overall survival rate was 98% at 4 years. And when they looked at patients who had undetectable minimal residual disease, the 4-year overall survival rate was 100%, which also suggests that MRD can help serve as a predictive marker of longer-term survival. So I think we have to also consider what the side effects are of combining these 2 agents and the most common adverse events were hematologic, which is expected based on what we know about the 2 classes. So I think the implication of the study is that giving 2 oral agents for a fixed period of treatment for 12 cycles is a rational approach that may spare patients indefinite therapy and can lead to positive outcomes, including in patients who have high-risk features with CLL.

Dr. John Sweetenham: Yeah, the other interesting observation that was made in the abstract, which I found to be really encouraging, was the fact that a number of these patients apparently have been re-treated successfully upon progression with ibrutinib again, which seems to be somewhat reassuring as well.

Dr. Marc Braunstein: That's right. There were 4 patients who started re-treatment in the study and perhaps we'll see the outcomes of that small subgroup are at the poster presentation. But I think when we discuss fixed-duration treatment, it also opens the door to potentially re-challenging patients when they relapse. We know that when we stop single-agent BTK inhibitors, which are historically given indefinitely in patients with CLL, those patients who stop, many will relapse, but you can potentially re-challenge them with the BTK inhibitor. So this study with the CAPTIVATE trial gives us some liberty to discontinue therapy, but also considering re-challenging upon relapse.

Dr. John Sweetenham: Yeah, absolutely. Moving on to aggressive B-cell lymphoma, now, the next abstract I'd like to discuss with you is Abstract 7525. I find this one particularly interesting as the continued excitement around CAR T cell therapy for relapsed aggressive lymphoma remains high at the moment. It's intriguing that t cell-engaging antibodies also have been reported, at least, to have remarkable activity in this set of diseases. So can you take us through Abstract 7525 and what they're reporting?

Dr. Marc Braunstein: Absolutely. Bispecific antibodies represent an emerging field in multiple hematologic malignancies, and this is a class of antibodies that bind to both the tumor cell as well as

T-cells, and activate T-cell immunity against the tumor cell. So epcoritamab is a bispecific antibody that binds to CD3, which is expressed on T cells, and CD20, which is expressed on B cells. And Thieblemont et al published results in the Journal of Clinical Oncology last year in a phase I/2 study that looked at epcoritamab in patients with diffuse large B cell lymphoma following 2 prior lines of therapy, and this was given subcutaneously until progression of disease. In that study, at a median follow-up of about 11 months, the overall response rate was 63% with 39% complete remissions.

So the EPCORE NHL-1 study, which is being presented at this year's ASCO meeting, is presenting the updated results of that study looking at patients with diffuse large B cell lymphoma that includes a small population as well of patients with high-grade B cell lymphomas and primary mediastinal B cell lymphomas who had at least 2 prior lines of therapy. In this presentation, 157 patients were included in this study, and 61% had primary refractory disease, and actually, 39% had prior CAR T-cell therapy, of whom 75% progressed within 6 months. So these were patients who were not only refractory to treatment but also had prior T-cell therapy.

So at a median follow-up of 20 months, the overall response rate was 63% and the complete response rate was again about 39%, and the median duration of complete remission was 21 months. In terms of overall survival, the median was about 19 months, which is substantial for this group of patients who really wouldn't be expected to respond very well to conventional therapies.

As we know, T-cell-engaging therapies, such as these bispecific antibodies or CAR T-cells have the potential risk for certain immune-related adverse events, including cytokine release syndrome or icons, and a neurologic syndrome related to the therapy. And it's worth noting that the CRS in this study was predominantly low-grade. There were only 3% of patients who had grade III CRS, and 9 patients, or 6% had grade I to II icons. I think that also reflects how we're better managing those side effects and intervening earlier. So I think the results are impressive from the standpoint of the population studied, who were quite refractory to treatment and show relatively high rates of response. In fact, the median overall survival was not reached in the overall population.

So I think what we take away from this abstract is that bispecific antibodies are going to play a vital role in the relapse-refractory setting for large cell lymphoma and may also offer an alternative to patients who aren't necessarily fit for CAR T-cell therapy, which plays a vital role in patients who are both refractory to first-line therapy or relapse-refractory to subsequent disease. So these are very encouraging results, and I'm sure we'll see randomized data as well in the future, further supporting the use of bispecific antibodies like epcoritamab.

Dr. John Sweetenham: Yeah, I agree. Thanks, Marc. I think that's a great summary. And it's particularly exciting to me that the investigators were able to achieve this kind of level of response and progression-free survival with a subcutaneous treatment. It's really quite remarkable and really exciting to see that.

We're going to wind up with our final abstract today, which is looking at the utilization of circulating tumor DNA in, again, in patients with aggressive B cell lymphoma. This is Abstract 7523, so maybe you could walk us through this one, Marc.

Dr. Marc Braunstein: Absolutely. So this is a poster being presented by Dr. Herrera looking at a, I guess you could call it a biomarker in the blood using circulating tumor DNA in patients with newly diagnosed diffuse large B cell lymphoma in the POLARIX study. So the results of the phase 3 POLARIX study were published last year in the New England Journal of Medicine and showed improvement in progression-free survival with the addition of these anti-CD79b antibody polatuzumab to standard R-CHOP chemotherapy compared to R-CHOP alone. And this study actually led to the approval of first-line treatment that includes polatuzumab.

In the abstract being presented by Dr. Herrera, the investigators looked at the value of circulating tumor DNA as a potential marker to serve as a guide for prognosis and predicting longer-term responses, particularly when the blood is cleared of circulating tumor DNA. So the study involved 654 patients who had ctDNA results both at baseline and then with longitudinal assessment, and they used an assay called the CAPP-Seq assay to assess circulating tumor DNA and assess for its clearance. In the study, undetectable circulating tumor DNA was achieved in 57% of patients who got the polatuzumab R-CHP combination and 59% of the patients who got R-CHOP by cycle 5 and then 6% in the polatuzumab group at 67% in the R-CHOP group.

So the rates of circulating tumor DNA clearance were similar between the 2 arms. But what's notable is that patients in the polatuzumab arm who achieved a complete response at the end of treatment plus cleared their circulating tumor DNA had superior progression-free and overall survival compared to patients who achieved a CR but retained circulating tumor DNA in their blood.

And this has implications because it might help gauge, for example, if patients may need additional cycles to clear the circulating tumor DNA, although we still need more data to answer whether that's necessary or not. And it may help serve as a predictive marker for longer-term remission, particularly in patients who perhaps have higher risk factors at baseline. So I don't think this is necessarily ready for primetime to use in clinical practice, but it is intriguing to know that we could finally have a tumor-specific biomarker in the blood to help monitor patients and potentially predict their longer-term remissions.

Dr. John Sweetenham: Thanks, Marc. I agree. Great summary, and obviously there's still something to learn about the kinetics of the response and so on. And also, I suppose it raises the question of whether those patients who still have detectable levels should be switched at the end of therapy to some kind of preemptive second-line therapy. And these are obviously all questions for the future, but it's going to be very interesting to watch this space, I think, and see how this story develops.

Dr. Marc Braunstein: Absolutely. And my colleagues in the solid tumor space are already using circulating tumor DNA, for example, in colon cancer, to help with surveillance. So perhaps this could be a tool to use to predict relapse also in patients who are on surveillance after their treatment. But again, as you alluded to, we need more data to address that.

Dr. John Sweetenham: Well, thanks so much, Marc, for sharing your insights with us today on a really interesting set of abstracts coming up at the June meeting. And thanks for joining us on the ASCO Daily News Podcast.

Dr. Marc Braunstein: Thank you for inviting me.

Dr. John Sweetenham: And thank you to our listeners for joining us today. You'll find links to the abstracts discussed today in a transcript of this episode. Join us again after the annual meeting for key takeaways on the late-breaking abstracts and other key advances from the ASCO Annual Meeting. And finally, if you value the insights that 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 to inform. This is not a substitute for professional medical care and is not intended for use in the diagnosis or treatment of individual conditions. Guests on this podcast express their own opinions, experience, and conclusions. Guest statements on the podcast do not express the opinions of ASCO. The mention of any product, service, organization, activity, or therapy should not be construed as an ASCO endorsement.

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Dr. Marc Braunstein

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Disclosures:

Dr. John Sweetenham:Consulting or Advisory Role: EMA Wellness

Dr. Marc Braunstein:Consulting or Advisory Role: Pfizer, Bristol-Myers Squibb/Celgene, Adaptive Biotechnologies, GlaxoSmithKline, ADC Therapeutics, Janssen Oncology, Abbvie, Guidepoint Global, Epizyme, Sanofi, CTI BioPharma Corp

Speakers' Bureau: Janssen OncologyResearch Funding (Institution): Janssen, Celgene/BMS