Does using daratumumab make response-monitoring difficult?

Does using daratumumab make response-monitoring difficult?


This week’s Ask Dr. Durie comes from a concerned
patient being treated with daratumumab, and the question will the use of the daratumumab
interfere with the monitoring and response assessment in my case. Will that daratumumab mess up the response
testing? And the unfortunate answer to that question
is yes. The daratumumab is a monoclonal antibody against
CD-38, which is a receptor on the surface of the myeloma. But the daratumumab antibody itself does show
up as a small spike in the blood of patients who are taking the dara. So that means that the dara spike could be
confused with an IgG myeloma spike, for example. And so, the SPEP and the IFE—immunifixation–results
during myeloma therapy with dara can be quite confusing. And so there are alternatives that need to
be discussed and planned for. And so first of all, if freelite is abnormal,
the kappa or lambda light chains, these are not affected and those can be used for monitoring. So this is a helpful thing to know. Obviously, other response tools can be used. One could do, for example, a whole-body PET-
CT scan. Also one could use other ways to look at the
myeloma. There is possibility to use a very specialized
test, called DIRA—and this a daratumumab-specific assay where you would show that the spike
is actually dara and not the myeloma-related IgG. And so if needs to be done, this is a decisive
way to show that spike is dara and not the residual myeloma protein. And so, this is a very important point to
be aware of. And also if you need to have a blood transfusion,
the daratumumab can actually interfere with the cross-matching for a blood transfusion. The BOTTOM LINE: For sure in this case, talk
to your doctor about the daratumumab, about ways in which the response is going to be
assessed. Also be just be alert to the fact, that if
a blood transfusion might be on the cards, that this something to plan for ahead, because
the direct cross-match could be difficult in the presence of the dara. So a very, very important question here: But
obviously the good news is that the daratumumab combinations are producing an excellent response,
and so the testing at these very, very low levels is important and encouraging to be
to assess how well the treatment is actually working.

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