What is a bi-clonal myeloma?

What is biclonal myeloma?

Biclonal myeloma is when a myeloma cell can make two different types of proteins. So when someone gets diagnosed with MGUS or multiple myeloma, we see those abnormal cells in the bone marrow frequently. People don't want a bone marrow biopsy every month or every three months or every six months to see what's going on with their disease.

So what we do is we treat the protein that the abnormal cell makes like a gas gauge for what's going on inside the gas tank. The gas tank is the bone marrow with a certain amount of plasma cells. You can follow the gas gauge or the protein level to see what's going on inside the bones, which is much more comfortable for the patient.

That protein that we make is an antibody protein or an immune protein that has a specific shape and it's shaped like a Y. We call this big part the heavy part because it's bigger, it's heavier. The heavy chain. Then there's a little part that can stick on the end. It's littler and it's lighter, so we call that the light chain. Light chains can be kappas or they can be lambdas.

Typically, when you have an abnormal myeloma cell, it's going to pick one type of protein to make. Every patient's going to be a little bit different. Some patients make IgA lambda or they make IgG kappa. In some different cases, you have patients that actually make two different types of protein, not just one. And so there's two different proteins to follow or two different gas gauges.

Is biclonal myeloma a better or worse prognosis?

We don't feel as comfortable when we see patients with two different types of protein. But there isn't a lot of information about what this means in terms of the patient's treatment and prognosis. Sometimes what we can see with treatment is that you see one type of myeloma causing a problem here, and a bone problem like what was pointed out in our sessions yesterday at the meeting in Vienna. Whereas the myeloma that sits in the bone marrow is doing something different. So we can see different behaviors from different clones.

Could M-spike be responding at different rates with biclonal myeloma?

Every patient who has biclonal myeloma responds differently to treatment. You can have patients where the two different proteins respond very similarly and go down together. And you can have other situations where one protein doesn't seem to respond as quickly as the other protein.

What is a good response to biclonal myeloma? Do both proteins have to be at the same level?

In myeloma, when we're watching how people respond to treatment, we have different levels of response called partial remission, which means it gets at least 50% better; a very good partial response, which means it's 90% better; and a complete response, which means that you can't see the abnormal protein on the basic blood testing. In biphenotypic myeloma, we have to see both proteins respond at those levels to give the patient that response.

So let's pretend one protein went away but the other one is still there at, let's say, 20% of what it was when we started. That response then is still only a very good partial remission, even though one of the proteins went away completely.

Is it possible for one protein to go down while the other goes up?

In patients with biphenotypic myeloma, you can definitely see one protein get better and the other get worse. That's rare. When we do see that, we call that clonal evolution, showing us that the myeloma has changed and that now you're starting to see one type of the myeloma evolve and get worse, whereas the other one is starting to fade away. When we see changes in the myeloma protein, if one protein is going up, and that's consistent with what we call relapse or progression, at that point your doctor might go ahead and change your treatment.