Dr. Durie discusses the use of mass spectrometry in the measurement and detection of multiple myeloma.
The BOTTOM LINE: Mass spectrometry offers a sensitive monitoring technique, potentially detecting lower levels of myeloma protein, providing valuable information for diagnosis, ongoing monitoring, and distinguishing treatment-related proteins. Efforts are being made to make this testing more widely accessible in the near future.
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This week's "Ask Dr. Durie" comes from a patient who wants to know more about mass spectrometry as a test for measuring the level of the myeloma protein in the blood? And so, this is actually a very important question. Mass spectrometry is a new method that allows us to measure much lower levels of myeloma protein in the blood.
It's a more sensitive test than using serum protein electrophoresis and immunofixation. So SPEP and what's called IFE. And so we are excited to have the possibility to have available this new mass spectrometry testing. To give you an idea, if one looks at patients who have had, what appears to be a complete remission using current standard testing with SPEP and immunofixation, about 20% of those patients will still have a positive result with mass spectrometry.
So with a more sensitive test, you can pick up more patients who may have a low level of residual disease. And what we learned is that this is important because among patients who appeared to have a complete remission, these individuals who are positive with the mass spec are the ones who have a shorter response to the treatment and stay in remission for a lesser period of time.
So this is a poorer outcome if this mass spec test is positive. And so, this is one advantage of mass spectrometry. The mass spectrometry can also be used in more of a routine fashion to initially detect the myeloma, a protein, and track it with monitoring on an ongoing basis. And this can be a helpful and simple way to evaluate myeloma.
In addition, what has become quite important is that using mass spectrometry, you can distinguish between the monoclonal protein, which is coming from the myeloma and the monoclonal protein, which may be given as part of a treatment, which is also a monoclonal protein. And so, this has become confusing when a patient is taking Daratumumab, for example, an anti-CD38 monoclonal antibody.
This could be confused with a low level of myeloma protein because both would show a low level spike in the blood. But using mass spectrometry, you can tell if the spike is myeloma or if it's Daratumumab, for example. So, this is important. In addition, there is a change that can occur on monoclonal proteins called glycosylation. This is a biochemical change that can surface on the protein. And this is linked to a tendency for amyloid formation where the proteins actually crosslink are more likely to crosslink if they have this glycol deletion factor. And so again, this is something that can be detected and distinguished using mass spectrometry.
So the BOTTOM LINE is that this is a new technique for sensitive monitoring. Hopefully, it will become more widely available in the coming months. Right now, samples can be sent to the Mayo Clinic, but it's hoped that some large groups like LabCorp and the like will also be making this testing available in the near future. And so, with the availability of testing, this can be a useful test for a variety of things, including both diagnosis, monitoring, and particularly to detect patients who will do particularly well.
Dr. Brian G.M. Durie (1942-2025) was the co-founder of the IMF. He was a Professor of Medicine, Hematologist/Oncologist, and Honoree MD at the University of Brussels.
