The Value of MRD Testing for Myeloma

This week's "Ask Dr. Durie" comes from a patient who wants to know about how valuable is MRD testing? Testing for minimal residual disease. And the answer is that this is quite important. Testing minimal residual disease is where you check to see if a small amount of myeloma is remaining in a bone marrow sample.

This can be by checking 100,000 cells where the sensitivity is called ten-to-the-minus-five or checking a million cells where the sensitivity would be ten-to-the-minus-six. And so, the value of this test is that if it's negative ten-to-the-minus-five or ten-to-the-minus-six, this means that there really is a very, very low level of myeloma in the body.

And this, is much better than just an assessment of a complete remission. And so, this is excellent news for a patient and can be very reassuring and certainly means that there's no immediate need for treatment. On the opposite side, if that type of MRD testing is positive, this means that there is definite residual myeloma in the bone marrow in the body and that this needs to be watched much more closely and that new therapy might actually be required.

Now, in the real world, setting the testing methods do still need some work, some standardization in terms of how they're collected, how they're processed and things like that. And so, one does need to be cautious right now until all of the standardization, in the real world, clinical setting is as well establish it. However, a main value for MRD testing is in clinical trials.

In clinical trials, if one treatment is being compared versus another in what's called a randomized trial, half the patients get one treatment and half get another. If more MRD occurs in one arm and one type of treatment. the amount, or the depth, then this means that one treatment is better than another. And so, this is obviously extremely helpful.

And that endpoint occurs much faster than waiting to see. How long does the remission last? And so we can do MRD testing after 9-to-12 months in patients where with these new therapies, remissions can last for five, six years or even longer. And so, this is a big advantage. What we're waiting for right now is to see if the FDA will indeed accept this approach.

To give what they would call accelerated approval based on achievement of this type of MRD negativity. And so, this is something that everyone is really hopeful about. So the BOTTOM LINE is: MRD testing is very useful, very useful. It needs to be standardized. And we are indeed waiting for the FDA to give its seal of approval so that it might be usable in the clinical trials setting.