Myeloma CAR T-Cell Therapy | How Is Success Measured?
How do you know if CAR T-cell therapy is working? Dr. Rahul Banerjee, a myeloma specialist, discusses how a patient’s response to CAR T-cell therapy is monitored and the role of measurable residual disease (MRD) in patient care.
Dr. Rahul Banerjee is a physician and researcher specializing in multiple myeloma and an assistant professor in the Clinical Research Division at the University of Washington Fred Hutchinson Cancer Center in Seattle, WA. Learn more about Dr. Rahul Banerjee.
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Transcript:
Katherine Banwell:
Well, how is success measured for CAR T-cell therapy?
Dr. Rahul Banerjee:
It’s a great question. So, traditionally, the metric in multiple myeloma has been achieving a complete response. So, having the M-spike, the antibodies that are produced by the myeloma cells, come down to zero.
So, either the M-spike, or for some patients, that may be the kappa or the lambda, which are fragments called light chains of antibodies, coming down to the normal range. The hard thing about those is that they take time. I’ve had patients who get CAR T therapy, and their bone marrow is completely clear, including MRD, measurable residual disease, as I’ll talk about in a second, but the M-spike takes months.
I had one patient where it took a year and a half for the M-spike to finally come down to zero. And it’s frustrating because I would say that, look, in my heart, you’re in remission, but if I were a lawyer, I wouldn’t be able to say that, because technically the M-spike is not quite zero yet. Your body’s just recycling that antibody. It’s not all the way down to zero, and that makes things tough. So, I don’t think that’s a great barometer to use.
I think MRD, which is again, a bone marrow test that we can spend more time talking about another day, is helpful. And at the one-month mark, achieving MRD negativity.
So, if you look in the bone marrow, by all the best tests available in the United States in the year 2024, and you can’t even find one out of a million cells that are myeloma, that’s obviously great to see.
That doesn’t mean that if it doesn’t happen, the patients are going to do poorly. There’s a lot more to CAR T than that. So, I think MRD negativity is probably the best short-term barometer. I think the best long-term barometer would be progression-free survival, which is, again, the medical word of saying how long is someone alive and in remission for.
