The use of DTT in the resolution of the interferences generated by daratumumab in the blood bank

Daratumumab (DARA) is a medication that in 2016 proved its efficacy and safety in the treatment of multiple myeloma. This product, based on a monoclonal antibody, technically generates an interference in most blood compatibility tests, artificially producing high blood pan-reactivity and incompatibility. The difficulty in finding blood compatible with the patient's serum can also mask the presence of other clinically significant alloantibodies and, above all, delays the timely delivery of erythrocyte concentrate, which, obviously, endangers the patient's life.

In transfusion medicine, very different strategies have recently been described for the resolution of this technical interference. We adopted the use of dithiothreitol (or DTT) to treat the red blood cells of the possible blood donors for the patient, thus achieving the elimination of this technical discrepancy and the adequate, safe and timely selection of this blood component. In the present paper, we describe the first case of a patient with a diagnosis of multiple myeloma treated with DARA, in which the interference caused by this drug in pretransfusion tests was successfully resolved.

Communication is a key element in the management of these patients. The doctor should inform the patient and the blood bank about the risk of presenting incompatible cross-tests when they are being treated with this medication. It is additionally recommended that all patients with multiple myeloma should undergo an erythrocyte phenotyping before receiving their treatment with DARA, and carry a card indicating that they are receiving this medication. Fortunately, hemolytic transfusion reactions have not yet been reported in these types of patients at the time of this publication.

For the staff at blood banks, it is evident that an additional operating procedure must be in place to describe the technical and administrative operation that must be followed from the admission of these patients to the hospital.

Technically speaking, we recommend, based on our experience reported in this case, the use of the DTT technique to resolve this discrepancy and technical difficulty in pretransfusion testing in patients treated with DARA.