2 September 2024 (Monday) - Daratumumab

I was asked a question today. M answer was “don’t know” so I did some finding out…
 
Daratumumab is effective in cases of multiple myeloma as a monotherapy in heavily treated patients with relapsed or refractory disease. It is a monoclonal antibody that specifically targets human CD38, which is highly expressed on myeloma cells.
However if a patient is on daratumumab when we do a group and save their antibody screen comes up positive in absolutely everything which makes crossmatching problematical.
So we send a sample to NHSBT and they send us compatible blood… what magic do they work?
 
Cells are treated with dithiothreitol (DTT) which removes the CD38. However whilst it is at it, it also removes the K antigen, and other antigens including ones of the Lutheran, Yt, Cromer, Dombrock, and Knops blood group systems.
 
Here’s an article describing what happens. There’s no magic. It’s quite straightforward. So why is this in the domain of the reference laboratory and not standard practice?

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