What is Monoclonal Gammopathy of Renal Significance (MGRS)?

What is Monoclonal Gammopathy of Renal Significance (MGRS)?

So monoclonal gammopathy of renal significance. It means that you have a protein that is M spike and that M spike is occurring with few cancer cells in the bone marrow, but there is no damage. It is no significant to those cells. Those cells have normal, those patients do not have any myeloma related symptoms. You have good hemoglobin, usually good bones with no pains.

But then you look at a subset of patients that have this kind of small M spike, and it's not enough to call it myeloma, but they do have kidney damage and it's a very evolving earlier. This was a recent definition. You know, I really think the only way to take monoclonal gammopathy of renal significance is to get a kidney biopsy. And the reason to get a kidney biopsy is you're going to treat those patients or you are going to make a decision if the patient has a renal failure, if they need to go for a kidney transplant or not.

So if you're evaluating a patient with bad kidneys and you find an M spike, the next question is going to be, do we need to treat the benign condition to control the protein that's causing the damage to the kidney? What is the patient ready to go for a kidney transplant and if the answer is yes to both of them, and the kidney biopsy is indicated an aggressive treatment of this M Spike to try to eliminate them is indicated so you can detect the kidney transplant.

But in general, monoclonal gammopathy of renal significance and at this time is an evolving diagnosis. And a lot of centers are hesitant to treat those patients just by looking at M spike and kidney. I usually request the kidney biopsy for those patients. I don't know what other centers do. There is really no standard way of doing that.

Why do you request a kidney biopsy?

If you have damage, if you have no criteria to diagnose myeloma and you have a patient renal insufficiency, most of those patients, especially in the older age group, will have hypertension, they have diabetes, they have some other cause. Then you can attribute the renal insufficiency to renal damage too. However, if you cannot justify that, but if that is rapidly worsening kidney function of the patient and hypertension for 20 years, and then all of a sudden the criteria that was 1.5 is up to four. Now, this is the kind of patient, you take the M spike.

I think the next question is going to be how do we certain that the M protein is causing the kidney damage? And if the question is yes or they ask the questions yes, then you need to go and get the kidney biopsy and the kidney biopsy would help guide subsequent management, including a kidney transplant. And if the kidney function worsens quickly and you don't want to do a kidney transplant in a patient, that that protein that's not controlled. So sometimes we get the biopsy, we treat them, and then we do the kidney transplant.

Monoclonal gammopathy of renal significance is a relatively new term that we've been using in patients who have MGUS or monoclonal gammopathy of undetermined significance. We start with having an M spike or a myeloma protein of less than three grams per deciliter and less than 10% plasma cells in the bone marrow. But what we see in patients with renal significance is that they do have a kidney problem related to this abnormal protein.

How can you manage monoclonal gammopathy of renal significance?

Monoclonal gammopathy of renal significance is an area that we're very interested in in terms of how to manage this disease. What we're thinking is, is that people are having damage from MGRS that they actually need treatment for their monoclonal gammopathy instead of watch and wait approach.

Is the treatment for MGRS the same as myeloma treatment?

So in terms of treatment for MGRS, we’re typically talking about myeloma based therapies that we would use to treat somebody who has traditionally symptomatic multiple myeloma.

What type of medications can be used with MGRS?

When people have a kidney problem like MGRS, we have to pay special attention to the medications that we use. The medications that we use sometimes have to be dosed differently, or we have to pick different medications for treatment. But medications like lenalidomide, bortezomib, and dexamethasone can still be used. We just have to pick the right doses for the kidney function. Even when patients go on dialysis, we can still use those medications. But again, we just have to be very specific in how we dose them.