Can someone be MRD negative, and not in a complete response?

One of the most confusing pictures that we have clinically sometimes is that patients are not in a quote unquote complete response, and yet they're MRD negative in their bone marrow. How does this happen? Well, first of all, remember that the bone marrow biopsy is a sample. Certainly, we can't sample the entire bone marrow.

And so it's possible to place that we took a sample from doesn't necessarily have a place that you may have myeloma. That's one possibility. The second possibility is that it's possible that you have myeloma not in the bone marrow, but maybe in a plasmacytoma and that's what producing those proteins. The third thing that's possible is it takes time for that protein that was sitting in your body to really degrade.

So maybe your bone marrow will reflect zero disease. And truly, there aren't any plasma cells, but it's taking your body some time to break it down and get rid of it.