Dr. Monty Pal speaks with internationally acclaimed hematologists Dr. Vincent Rajkumar and Dr. Saad Usmani about the AQUILA trial in high-risk smoldering multiple myeloma, as well as advances in CAR-T and other evolving treatment strategies in the myeloma space.

TRANSCRIPT

Dr. Monty Pal: Hello everyone and welcome to the ASCO Daily News Podcast. I'm your host, Monty Pal. I'm a medical oncologist, underline medical oncologist, a professor, and vice chair of academic affairs at the City of Hope Comprehensive Cancer Center in Los Angeles. You're going to understand why I underlined "medical oncologist" there. I'm actually on the line today with two amazing hematologists. Today, we're going to actually explore treatments for high-risk smoldering multiple myeloma following the FDA's approval last year of daratumumab for the first-ever treatment of this indication.

Now, this is based on the AQUILA trial, and this represents a huge shift in our traditional watch-and-wait approach to active disease interception. We're going to consider whether this landmark trial published in The New England Journal translates to day-to-day practice. I think it does, and we'll certainly make an argument for that. And I'm so fortunate today to have two internationally acclaimed experts here in the conversation: Dr. Vincent Rajkumar, senior author on the manuscript, and Dr. Saad Usmani, also an expert in his own right in myeloma.

Dr. Rajkumar is the lead investigator of the AQUILA study. He's a professor of medicine and consultant in the divisions of hematology and hematopathology at the Mayo Clinic in Rochester, Minnesota. He actually chairs the Myeloma, Amyloidosis, Dysproteinemia Program. He is also editor-in-chief of the Blood Cancer Journal.

Dr. Usmani, he and I actually go way, way back. We actually did the AACR Molecular Biology in Clinical Oncology course, I want to say in 2006, so this is our 20-year anniversary, Saad. He's the chief of the myeloma service at the MSK Cancer Center and a professor of medicine at the Weill Cornell Medical College in New York.

Saad, Vincent, welcome.

Dr. Saad Usmani: Thank you so much for having me, Monty.

Dr. Vincent Rajkumar: Yeah, thanks, Monty. A pleasure to be here.

Dr. Monty Pal: Thanks. And just a quick note for our listeners, all of our disclosures are available in the transcript of this episode. First off, Saad, did I get that right? Was it 2006 when we did that course together?

Dr. Saad Usmani: Yeah, 20 years. We are coming up to our 20-year anniversary. It's remarkable to have seen our careers move the way they have, Monty.

Dr. Monty Pal: Oh my gosh. And for all the fellows who are on the line, that AACR Molecular Biology and Clinical Oncology course, it's sometimes overlooked. Wonderful primer on translational science.

Okay, now we're going to get to the heart of the matter here, the AQUILA trial. So this was a study, Vincent, that you led. I wonder if you'd walk us through the primary endpoints in the study. What are we looking at in the AQUILA trial specifically?

Dr. Vincent Rajkumar: Thanks so much. Again, as you mentioned, smoldering multiple myeloma has just been a condition that we watch and wait. And the first thing that I want to clarify here is that the AQUILA trial is looking at only a subset of smoldering multiple myeloma. That is the high-risk smoldering multiple myeloma. It was defined the way high-risk smoldering myeloma was defined at the time the trial was designed. It randomized 390 patients. One arm got daratumumab single agent in an attempt to delay progression to active myeloma and possibly prolong survival. And the other arm was the traditional observation. The primary endpoint, therefore, was time to active multiple myeloma. Other endpoints included time to when patients needed to start therapy for active multiple myeloma, which can vary based on physician judgment, and overall survival. Of course, response rate, complete response rate, and others were also endpoints.

Dr. Monty Pal: That's interesting. And you know, I wanted you to riff a little bit on this definition of high-risk smoldering myeloma. Can you tell our audience how that's sort of evolved over the years?

Dr. Vincent Rajkumar: Yes. I mean, if you step back, monoclonal gammopathy of undetermined significance has only a 1% per year risk of progression. Smoldering multiple myeloma, all comers have a 10% per year risk of progression. And over the years, trials have been done in the whole population, and then more recently, we felt we should really focus on the people with high-risk smoldering, defined as a 50-50 risk of progression in 2 years. That's like a 25% per year risk of progression in the first 2 years, which is a very high risk for the patient and something that would justify prophylactic intervention.

And that definition initially was based on just high levels of monoclonal protein like more than 3 grams, the IgA subtype of myeloma, the suppression of uninvolved immunoglobulins. Others have used bone marrow flow cytometry markers, cytogenetics. Those combinations of factors were available at the time the AQUILA trial was designed, and a select combination was used. Later on, we found that we could match almost all of that in a very simple risk stratification using just the percentage of bone marrow plasma cells, the level of the M-spike, and the free light chain ratio, all three of which are available to all patients with smoldering at the time of diagnosis. So you don't need any special testing. So more than 20% plasma cells, more than 20 for the light chain ratio, and more than 2 grams for the M-spike. If someone has any two of the three, that is high-risk smoldering multiple myeloma according to the IMWG, but that definition, of course, came in 2020 after the AQUILA trial completed accrual.

Dr. Monty Pal: That's interesting because this sort of flips the traditional paradigm where biomarkers get more and more complex as time goes on. Am I right in saying this sort of simplifies things a little bit? It uses standard laboratory or clinical parameters to gauge this category?

Dr. Vincent Rajkumar: Absolutely. People were using suppression of uninvolved immunoglobulins, and those levels are not standardized, often vary by race. Also, the other aspect was the abnormal plasma cells on flow cytometry. Again, labs define it differently. So this makes it much more simple. But the IMWG also did a separate exploratory cohort within that paper where we added cytogenetics and we added scoring systems to improve on this further. So it simplified it for regular clinical practice and for like trials. But if you have a patient in front of you, the IMWG paper also has more complex scoring systems where you can take more than 20; 21 is more than 20, so is 51. And so, you can use the actual numbers that a patient has, additional variables like cytogenetics, and get a more refined estimate of what is the true risk of progression.

Dr. Monty Pal: That's really helpful. Now, you told us about the primary endpoints, you've helped us define high-risk smoldering myeloma. Can you give us a sense of the top-line results from AQUILA?

Dr. Vincent Rajkumar: Yes, I think the most important one was the primary endpoint, time to multiple myeloma, was at 5 years, the progression-free survival was 63% in the daratumumab arm compared to 41% in the observation arm. So, you know, approximately 60% of patients in the observation arm had already progressed by 5 years. And that number was about 40% for the daratumumab arm. We also looked at time to starting myeloma therapy, which is clinically actually quite meaningful because, you know, myeloma therapy means patients get a quadruplet for induction, they get stem cell transplant, they get endless maintenance, they get ongoing therapy virtually for the entire duration. So, preventing the need for myeloma therapy is in and of itself, I think, a major endpoint. And that at 3 years, 40% of people in the observation arm required full myeloma therapy compared to only 20% in the daratumumab arm. So there's a significant reduction in the risk of developing active myeloma as well as the need for myeloma therapy by using a time-limited 3 years of daratumumab single agent.

Dr. Monty Pal: Perfect summary of the results. And maybe, Saad, I'm going to bring you into the conversation now. How does this sort of influence your day-to-day practice for smoldering myeloma? Is this something that you've incorporated for that high-risk subset?

Dr. Saad Usmani: Thank you, Monty, and I agree. I think that's a really nice summary from Vincent. This study is very important for several reasons. It's actually the third clinical trial that has demonstrated that patients who are in the high-risk smoldering myeloma category benefit from an early intervention that delays the progression to active myeloma or to end-organ damage. And so having a nuanced discussion with our patients in the clinic becomes very important. Having this discussion around as an option becomes very important. And like Vincent said, when we look at that high-risk smoldering myeloma patient population, someone who has 22, 23% plasma cells versus, you know, 45, 50, you know, it's going to be a different discussion each time. But I think it's a very important first step. And I think this sets up the stage for ...