What are myeloma markers? How are they useful?

What are myeloma markers? How are they used? In multiple myeloma, we're actually fortunate enough to have a number of tests that we can use in patient's blood to follow their disease and see how our treatments are working. There are a couple of different ones that we use. The one that we classically use is called the M-spike or monoclonal protein. That is the protein that the myeloma cells produce and they produce it in large enough numbers that we can detect it on a specific test called a protein electrophoresis. And that gives us an exact quantification of the protein that the myeloma cells are producing and we know that that correlates with the amount of myeloma that's in a patient's body. So as we treat, we follow that number to determine the extent to which patients are responding to treatment and use that to inform some of the treatments that we do. There are a couple of other markers that we use. One of them is called the serum-free light chain assay. That is a fragment of that protein that the myeloma produces that we can also follow across time. We know that the amount of free light chains that are detected in the patient's blood correlate with the amount of disease and how they're responding as well. So those are two pretty powerful tools that we use. Pretty much every next cycle of therapy, usually that ends up being about every four weeks, we can check for those proteins also in patient's urine, usually that requires a 24-hour collection. We follow disease response by imaging, sometimes using PET scans. For a couple of other ways to follow disease, we can also use some more sophisticated tests that are often done on bone marrow biopsies like minimal residual disease testing, which actually looks at the amount of DNA that we can detect of the myeloma in a patient's bone marrow biopsy. So those are just a few of the different markers we use to follow how well we're doing with the treatment. For the most part, when we're measuring how someone's disease is getting better or worse, we use the term myeloma markers. What are they? Well, plasma cells are immune cells. They make antibodies to fight infection. And in myeloma, they still make that antibody, but it's kind of messed up. So it doesn't work like an antibody, but it still has some of the core features and core components. An antibody typically has two parts. The bottom part is heavy, so we call it the heavy chain. And there's five different types of heavy chains in humans. And because they're all immune globulins, we call them Ig's. So we have IgG, IgA, IgM, IgD, and IgE. And the top part is light. We call that the light chain. And there's two types of light chains, kappa and lambda. And you can have all different combinations. IgG kappa, IgA lambda. Sometimes the plasma cells say, you know what, I'm not even going to make a heavy chain. I'm just going to make a light chain. I'm too tired. So you have free kappa or free lambda. Whatever type of plasma cell becomes malignant, it makes too much of that particular protein So it doesn't necessarily mean you do better or worse with any one of these. It's just if I know you have IgG lambda, when your myeloma gets worse, your IgG will go up, your lambda will go up, and the M spike will go up. And the M spike is kind of all the bad. If you think about IgG as a heavy chain, forget the light chain, it's just so small. But if the IgG, you have good and bad. You have normal IgG. So you can have an IgG of 3000. And if you have an M spike of 2.7, that means 2700 of that 3000 is bad, and that 300 that left over is good. So we really look for all of these numbers to go up or down. In general, when those numbers go up, more bad cells growing. When they go down, bad cells are dying.