MRD Monitoring in Multiple Myeloma

Keith Stewart, MBChB: Since you brought up MRD, or minimal residual disease, monitoring, let’s take a quick poll of each of you, are you using it, and at what point would you measure it first?

Natalie S. Callander, MD: We’ve had a huge debate on this institutionally. We’re doing it by consensus post-transplant. What we’re not doing is using a single result, like Pete says, to determine ending treatment unless somebody’s on a clinical trial. Patients are asking for it. Many people are not sure what you do with it. Maybe 90 days post-transplant isn’t the right point to test it. It should be at a year later on. That’s a possibility.

Nooper Raje, MD: I don’t routinely do it in my practice. And that’s largely because we’re not making any treatment-related decisions. The 1 subset of patients where I do look at MRD is the high-risk patient population. There are enough data now. We’ve been talking about transplant here, but it doesn’t matter how you do that MRD-negativity. If you can sustain it with the maintenance that we do in the United States, I do think we ask the question on transplant now. As of right now, only high-risk patients.

Thomas G. Martin, MD:We routinely do it. When patients achieve a CR [complete response], whether it’s pretransplant, 3 months post-transplant, or a year post-transplant, we do MRD testing routinely. That is our clinical practice. We try not to make any clinical decisions based on it. But our goal is to get to MRD negative specifically for the high-risk patients. And for other patients, it’s still our hope that we can get there.

Keith Stewart, MBChB: Tom, if you’re not making any decisions, why bother doing it? That doesn’t make much sense.

Thomas G. Martin, MD:If you have sustained MRD negativity, and you have toxicity, the clinical decisions that we’re making, somebody has a year of sustained MRD negativity and then has neuropathy or has GI [gastrointestinal] toxicity, it’s a lot easier to take them off their medicine. When we look back at our data and say, are we really not making decisions, about a third of the time, we are making a change based on the MRD.

Keith Stewart, MBChB: At the Mayo [Clinic], I know that my colleagues were quite insistent that we do MRD testing at day 100. To me, this was totally illogical, because it wasn’t going to change what we did. But that’s what they were doing. I was a bit like you, Natalie. I was waiting till there was a decision point to be made, like Tom said. Maybe they’re getting toxicity from maintenance, and you’re probably looking for an excuse to take them off if they’re MRD negative on a couple of occasions.

Natalie S. Callander, MD: Exactly.

Keith Stewart, MBChB: Or alternatively, if it was a young patient, and they still have quite a high reading, despite a normal bone marrow and a negative blood test. Then, it does beg the question of whether one should escalate therapy in that patient.

Transcript edited for clairty.